Heat exchanger

A heat exchanger body that includes a circulation path through which a coolant is circulated and performs heat exchange between the coolant flowing through the circulation path and an electronic component; a circulation pump that supplies the coolant to the heat exchanger body; an accumulation determination unit that determines whether a foreign matter accumulation condition is fulfilled that is satisfied when foreign matter is expected to be accumulated in at least a part of the circulation path; and a process execution unit that in response to the foreign matter accumulation condition being satisfied, executes a foreign matter cleaning process of removing the foreign matter accumulated in the circulation path and cleaning the circulation path. In the foreign matter cleaning process, the process execution unit reduces an amount of coolant supplied from the circulation pump so that the coolant has a superheating degree in a nucleate boiling region.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the U.S. bypass application of International Application No. PCT/JP2019/007734 filed on Feb. 28, 2019 which designated the U.S. and claims priority to Japanese Patent Application No. 2018-074812 filed on Apr. 9, 2018, Japanese Patent Application No. 2018-105121 filed on May 31, 2018, and Japanese Patent Application No. 2018-112301 filed on Jun. 12, 2018, the contents of all of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a heat exchanger.

BACKGROUND

JP 2017-67412 A discloses a known technique of generating bubbles of a liquid coolant using ultrasonic waves to clean off foreign matter accumulated in a coolant circulation path in a heat exchanger (see, for example, JP 2017-67412 A). In JP 2017-67412 A, the heat exchanger is provided with an ultrasonic wave generation unit that generates ultrasonic waves.

JP 2016-205802 A discloses a heat exchanger used for cooling a plurality of semiconductor modules with an integrated semiconductor device. The heat exchanger includes a plurality of channel pipes that are laminated to sandwich a single semiconductor module from both sides, and is configured such that the plurality of channel pipes communicate with each other. The heat exchanger is configured such that each of the plurality of channel pipes arranged to be laminated is partitioned by an intermediate plate into two main channels and each of the two main channels is partitioned by an internal fin into a plurality of narrow channels. The heat exchanger increases a heat transfer area using the internal fin to improve the heat exchange performance between the heat exchanger and the semiconductor module.

JP 2010-10418 A discloses a laminated cooler as a heat exchanger. The cooler is configured such that a coolant is circulated through a coolant channel in a cooling pipe to cool an electronic component arranged in contact with the cooling pipe.

SUMMARY

A first aspect of the present disclosure is a heat exchanger that cools a cooled object by heat exchange between the cooled object and a liquid coolant, the heat exchanger including: a heat exchanger body that includes a circulation path through which the coolant is circulated and performs heat exchange between the coolant flowing through the circulation path and the cooled object; a coolant supply pump that supplies the coolant to the heat exchanger body; an accumulation determination unit that determines whether a foreign matter accumulation condition is fulfilled that is satisfied when foreign matter is expected to be accumulated in at least a part of the circulation path; and a process execution unit that in response to the foreign matter accumulation condition being satisfied, executes a foreign matter cleaning process of removing the foreign matter accumulated in the circulation path and cleaning the circulation path, wherein in the foreign matter cleaning process, the process execution unit reduces an amount of coolant supplied from the coolant supply pump so that the coolant has a superheating degree in a nucleate boiling region.

A second aspect of the present disclosure is a heat exchanger including: a channel pipe that has an outer surface serving as a heat exchange surface for an external heat exchange object; a plate-shaped partition member that partitions the channel pipe into a plurality of channels through which a heat transfer medium flows, and an internal fin that is provided in the channel pipe to divide each of the plurality of channels into a plurality of narrow channels, wherein the partition member is provided with a communication hole through which at least two of the plurality of channels communicate with each other, the internal fin is configured to have a corrugated cross-sectional shape in which a plurality of convex portions and a plurality of concave portions facing the partition member are alternately formed and to be joined to the partition member at the convex portions; and the communication hole is provided at a joining portion of the partition member to which the convex portion of the internal fin is joined.

A third aspect of the present disclosure is a heat exchanger including: a cooling pipe inside which is provided a coolant channel through which a coolant is circulated; and a first electronic component and a second electronic component that are arranged thermally in contact with a cooling surface of the cooling pipe, wherein: the first electronic component is arranged on an upstream side of the second electronic component in the coolant channel; the coolant channel has an intermediate region located on a downstream side of the first electronic component and an upstream side of the second electronic component, an upstream region located between an upstream end of the first electronic component and a downstream end of the first electronic component, and a downstream region located between an upstream end of the second electronic component and a downstream end of the second electronic component; and a fluid diode unit is provided in the intermediate region, in the upstream region and the downstream region, the cooling pipe includes an internal fin that partitions the coolant channel into a plurality of branch channels that extend parallel to each other in a channel direction, and the fluid diode unit causes a channel resistance in a direction from the downstream region toward the upstream region to be higher than a channel resistance in a direction from the upstream region toward the downstream region.

A fourth aspect of the present disclosure is a heat exchanger including: a cooling pipe inside which is provided a coolant channel through which a coolant is circulated; and a first electronic component and a second electronic component that are arranged thermally in contact with a cooling surface of the cooling pipe, wherein: the first electronic component is arranged on an upstream side of the second electronic component in the coolant channel; the cooling pipe includes an internal fin that partitions the coolant channel into a plurality of branch channels that extend parallel to each other in a channel direction; the coolant channel has an intermediate region located on a downstream side of the first electronic component and an upstream side of the second electronic component, an upstream region located between an upstream end of the first electronic component and a downstream end of the first electronic component, and a downstream region located between an upstream end of the second electronic component and a downstream end of the second electronic component; and only in the intermediate region among the upstream region, the intermediate region, and the downstream region, the internal fin is provided with a diffusion unit through which adjacent branch channels communicate with each other.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As disclosed in JP 2017-67412 A, the heat exchanger provided with the ultrasonic wave generation unit as a dedicated device for foreign matter cleaning inevitably causes an increase in the number of components and complexity of the device. The increase in the number of components and complexity of the device are factors that increase the manufacturing cost and reduce the applicability of the product, and are thus undesirable.

In the heat exchanger disclosed in JP 2016-205802 A, as the amount of heat generated by the semiconductor module is increased, a cooling medium flowing through the main channels of the channel pipe is more likely to boil. When the cooling medium boils, a pressure in the main channels is increased, and thus the cooling medium is less likely to flow through the channel pipe. If an imbalance in the pressure between the two main channels occurs, the cooling medium is more likely to flow through one of the two main channels and less likely to flow through the other main channel, resulting in an imbalance in the flow rate. The imbalance in the flow rate of the cooling medium is a factor that deteriorates the heat exchange performance of the heat exchanger, which is a problem.

In the laminated cooler disclosed in JP 2010-10418 A, the following problem may occur. Specifically, in a case where a plurality of electronic components are arranged side by side on an upstream side and a downstream side of the coolant channel in the cooling pipe, when the amount of electric current flowing through the electronic components is increased, the amount of heat generated by the electronic components is also increased. This may cause a situation where a temperature of a liquid coolant such as water is locally increased and the liquid coolant boils at a position close to a heat generating unit of the electronic component. In that case, the vaporized coolant may hinder smooth flow of liquid coolant in the cooling pipe. Thus, at the position in the coolant channel close to the electronic component, the liquid coolant is less likely to be supplied, and this may make it difficult to improve the cooling performance. In addition, particularly, in a region in which the electronic component on the downstream side is arranged in the coolant channel, the coolant vaporized by heat of the electronic component on the upstream side is supplied, and the coolant is easily evaporated due to the heat of the electronic component on the downstream side. In that case, in the vicinity of the electronic component on the downstream side, the supply amount of liquid coolant tends to be reduced, and due to what is called dry-out, the cooling performance may be deteriorated.

Thus, in order to ensure sufficient cooling performance, proper thermal design is required, such as an increase in the flow rate of the entire coolant. However, in that case, the cooler requires more energy for cooling, and thus tends to be disadvantageous in terms of cooling efficiency.

The present disclosure is to provide a technique for improving heat exchanger performance.

A first aspect of the present disclosure is a heat exchanger that cools a cooled object by heat exchange between the cooled object and a liquid coolant, the heat exchanger including: a heat exchanger body that includes a circulation path through which the coolant is circulated and performs heat exchange between the coolant flowing through the circulation path and the cooled object; a coolant supply pump that supplies the coolant to the heat exchanger body; an accumulation determination unit that determines whether a foreign matter accumulation condition is fulfilled that is satisfied when foreign matter is expected to be accumulated in at least a part of the circulation path; and a process execution unit that in response to the foreign matter accumulation condition being satisfied, executes a foreign matter cleaning process of removing the foreign matter accumulated in the circulation path and cleaning the circulation path, wherein in the foreign matter cleaning process, the process execution unit reduces an amount of coolant supplied from the coolant supply pump so that the coolant has a superheating degree in a nucleate boiling region.

A second aspect of the present disclosure is a heat exchanger including: a channel pipe that has an outer surface serving as a heat exchange surface for an external heat exchange object; a plate-shaped partition member that partitions the channel pipe into a plurality of channels through which a heat transfer medium flows, and an internal fin that is provided in the channel pipe to divide each of the plurality of channels into a plurality of narrow channels, wherein the partition member is provided with a communication hole through which at least two of the plurality of channels communicate with each other, the internal fin is configured to have a corrugated cross-sectional shape in which a plurality of convex portions and a plurality of concave portions facing the partition member are alternately formed and to be joined to the partition member at the convex portions; and the communication hole is provided at a joining portion of the partition member to which the convex portion of the internal fin is joined.

A third aspect of the present disclosure is a heat exchanger including: a cooling pipe inside which is provided a coolant channel through which a coolant is circulated; and a first electronic component and a second electronic component that are arranged thermally in contact with a cooling surface of the cooling pipe, wherein: the first electronic component is arranged on an upstream side of the second electronic component in the coolant channel; the coolant channel has an intermediate region located on a downstream side of the first electronic component and an upstream side of the second electronic component, an upstream region located between an upstream end of the first electronic component and a downstream end of the first electronic component, and a downstream region located between an upstream end of the second electronic component and a downstream end of the second electronic component; and a fluid diode unit is provided in the intermediate region, in the upstream region and the downstream region, the cooling pipe includes an internal fin that partitions the coolant channel into a plurality of branch channels that extend parallel to each other in a channel direction, and the fluid diode unit causes a channel resistance in a direction from the downstream region toward the upstream region to be higher than a channel resistance in a direction from the upstream region toward the downstream region.

A fourth aspect of the present disclosure is a heat exchanger including: a cooling pipe inside which is provided a coolant channel through which a coolant is circulated; and a first electronic component and a second electronic component that are arranged thermally in contact with a cooling surface of the cooling pipe, wherein: the first electronic component is arranged on an upstream side of the second electronic component in the coolant channel; the cooling pipe includes an internal fin that partitions the coolant channel into a plurality of branch channels that extend parallel to each other in a channel direction; the coolant channel has an intermediate region located on a downstream side of the first electronic component and an upstream side of the second electronic component, an upstream region located between an upstream end of the first electronic component and a downstream end of the first electronic component, and a downstream region located between an upstream end of the second electronic component and a downstream end of the second electronic component; and only in the intermediate region among the upstream region, the intermediate region, and the downstream region, the internal fin is provided with a diffusion unit through which adjacent branch channels communicate with each other.

In the heat exchanger of the first aspect, when foreign matter is expected to be accumulated in at least a part of the circulation path of the heat exchanger body, the amount of coolant supplied to the heat exchanger body is reduced so that the coolant has a superheating degree. In a case where the coolant has a superheating degree in the nucleate boiling region, gas bubbles are generated in the circulation path, and the foreign matter accumulated in the circulation path can be removed by a force generated when a volume change of the gas bubbles or disappearance of the gas bubbles occurs.

Such a configuration capable of removing the foreign matter by adjusting the amount of coolant supplied to the heat exchanger body does not require a dedicated device such as an ultrasonic wave generation unit, leading to simplification of the heat exchanger. Thus, the heat exchanger of the first aspect can remove the foreign matter accumulated in the circulation path and clean the circulation path with a simple configuration.

The expression “the coolant has a superheating degree in the nucleate boiling region” means a state in which, with regard to a saturation start point and a burnout point indicated by a boiling curve, the superheating degree of the coolant exceeds the saturation start point and is the burnout point or less. The term “superheating degree” means a temperature difference between a temperature of a heat transfer portion between the cooled object and the coolant and a saturation temperature of the coolant, and is defined, for example, as a value obtained by subtracting the saturation temperature of the coolant from the temperature of the heat transfer portion between the cooled object and the coolant.

In the heat exchanger of the second aspect, the heat transfer medium flowing in the channel pipe exchanges heat with the external heat exchange object through the heat exchange surface which is the outer surface of the channel pipe. The channel pipe is partitioned by the plate-shaped partition member into the plurality of channels, and the heat transfer medium flows each of the plurality of channels. At least two of the plurality of channels communicate with each other through the communication hole provided in the partition member.

Thus, for example, even when an imbalance in pressure occurs between at least two of the channels due to boiling of the heat transfer medium or the like, by distributing the pressure so that the pressure in the channel on the high-pressure side is shared with the channel on the low-pressure side through the communication hole of the partition member, the imbalance in the pressure can be reduced. Therefore, it is possible to prevent the imbalance in the pressure between the plurality of channels formed by partitioning the channel pipe.

In the heat exchanger of the third aspect, the fluid diode unit is provided in the intermediate region. Thus, even when a part of the liquid coolant in the downstream region is evaporated to be vapor by heat of the second electronic component on the downstream side, the vapor can be prevented from flowing backward to the upstream region. As a result, the vapor is discharged easily and early from a downstream end of the coolant channel.

Therefore, a smooth flow of coolant from the upstream side toward the downstream side of the coolant channel can be ensured. As a result, the cooling performance for not only the first electronic component but also the second electronic component can be improved.

In the heat exchanger of the fourth aspect, the diffusion unit is formed in the intermediate region. Accordingly, even when the coolant is evaporated to vapor by heat of the first electronic component and the second electronic component, the vapor can be diffused in a direction orthogonal to the channel direction through the diffusion unit. Thus, the vapor generated in the branch channel in the vicinity of a center of the coolant channel can be released outward. Accordingly, in the vicinity of the center, the liquid coolant can be smoothly introduced and efficient cooling of the first electronic component and the second electronic component can be ensured.

As described above, the above aspects can improve heat exchanger performance.

In the embodiments, portions identical or equivalent to those described in a preceding embodiment are given the same reference numerals and may not be redundantly described. When only a part of a component is described in the embodiments, the component described in the preceding embodiment can be applied to the other parts of the component. Even if not explicitly stated, the embodiments may be partially combined, provided there is no inconsistency in the combination.

First to seventh embodiments of the heat exchanger of the first aspect of the present disclosure will be described with reference to the drawings. An object of the disclosure is to provide a heat exchanger capable, with a simple configuration, of removing foreign matter accumulated in a circulation path through which a coolant is circulated, thereby improving heat exchanger performance.

First Embodiment

A heat exchanger1of the present embodiment will be described with reference toFIGS.1to11. The heat exchanger1is a device that performs heat exchange between a cooled object and a coolant. The heat exchanger1of the present embodiment is an in-vehicle device mounted on a vehicle, and is configured to cool a cooled object such as a heat generating device mounted on the vehicle.

As shown inFIG.1, the heat exchanger1includes a circulation circuit10through which a coolant is circulated, a circulation pump12that causes the coolant to be circulated, a heat exchanger body14that cools a cooled object by heat exchange between the cooled object and the coolant, a radiator16that causes the coolant to radiate heat, and a control device100.

The circulation circuit10is configured as a closed circuit. The circulation circuit10is filled with a liquid coolant. The coolant is composed of an antifreeze containing an anticorrosive that prevents generation of rust. The antifreeze is a known long-life coolant. The antifreeze is, for example, a liquid coolant obtained by adding an anticorrosive, an antioxidant, and the like to water containing ethylene glycol.

The circulation pump12is an electric pump provided in the circulation circuit10. The circulation pump12includes an electric motor, and is driven by a driving force of the electric motor. The circulation pump12can change a flow rate of the coolant in the circulation circuit10by changing a rotational speed of the electric motor (i.e., pump rotational speed). The pump rotational speed can be changed according to a control signal from the control device100(described later). In the present embodiment, the circulation pump12constitutes a coolant supply pump that supplies the coolant to the heat exchanger body14.

The heat exchanger body14is provided in the circulation circuit10. The heat exchanger body14includes a plurality of cooling pipes142that form a circulation path140through which the coolant is circulated, and performs heat exchange between the coolant flowing through the circulation path140and the cooled object.

The heat exchanger body14of the present embodiment is composed of a component cooler that is configured to cool, as the cooled object, an electronic component20used in an inverter mounted on the vehicle and cools the electronic component20by heat exchange between the electronic component20and the coolant. The heat exchanger body14is configured as a laminate in which the plurality of cooling pipes142are laminated with the electronic component20interposed between the plurality of cooling pipes142.

The electronic component20generates heat by energization. Thus, the electronic component20constitutes a heating element that generates heat by energization. The electronic component20is connected to a drive circuit22. The electronic component20is composed of, for example, a semiconductor module with an integrated semiconductor device composed of a SiC substrate that has better performance characteristics at high temperature than other semiconductor devices such as a semiconductor device composed of a Si substrate.

The drive circuit22constitutes an adjustment unit for adjusting the energization amount to the electronic component20. The drive circuit22is configured to be able to change the energization amount to the electronic component20according to a control signal from the control device100(described later).

The radiator16is provided on a coolant flow downstream side of the heat exchanger body14in the circulation circuit10. The radiator16causes the coolant whose temperature has been increased in the heat exchanger body14to radiate heat by heat exchange with outside air. The radiator16also functions as a coolant tank that stores the coolant. The radiator16may be configured to cause the coolant whose temperature has been increased in the heat exchanger body14to radiate heat by heat exchange with a heat transfer medium other than outside air.

Next, the control device100that constitutes an electronic control unit of the heat exchanger1will be described. The control device100is composed of a well-known microcomputer including a processor and a memory110, and a peripheral circuit of the microcomputer. The memory110of the control device100is composed of a non-transitory tangible storage medium.

An input side of the control device100is connected to a flow rate sensor101, a differential pressure sensor102, a coolant temperature sensor103, and the like as means for detecting a state of the coolant in the circulation circuit10and the like.

The flow rate sensor101is a sensor that detects a flow rate Gr of the coolant flowing into the heat exchanger body14. The flow rate sensor101is provided at a portion of the circulation circuit10between a coolant outlet of the circulation pump12and a coolant inlet of the heat exchanger body14.

The differential pressure sensor102is a sensor that detects a difference in pressure between the coolant inlet and a coolant outlet of the heat exchanger body14as a pressure loss ΔP of the heat exchanger body14. The differential pressure sensor102is configured to output, as the pressure difference, a value obtained by subtracting the pressure on the coolant outlet side of the heat exchanger body14from the pressure on the coolant inlet side of the heat exchanger body14.

The coolant temperature sensor103is a sensor that detects a temperature (i.e., coolant temperature Tw) of the coolant flowing into the heat exchanger body14. The coolant temperature sensor103is provided at a portion of the circulation circuit10between a coolant outlet of the radiator16and a coolant inlet of the circulation pump12.

The input side of the control device100is connected to a device temperature sensor104that detects a device temperature Td, which is a temperature of the electronic component20. The device temperature sensor104is configured to directly detect the device temperature Td. The device temperature sensor104may be configured to indirectly detect the device temperature Td on the basis of the energization amount to the electronic component20or the like.

Furthermore, the control device100is connected to a vehicle control device120so that the control device100can bidirectionally communicate with the vehicle control device120. The vehicle control device120controls driving operation of the vehicle and the like. Thus, the control device100can acquire information such as a traveling state of the vehicle via the vehicle control device120.

On the other hand, an output side of the control device100is connected to the electric motor of the circulation pump12, the drive circuit22of the electronic component20, and the like. The control device100controls the electric motor of the circulation pump12, the drive circuit22of the electronic component20, and the like on the basis of information acquired from various sensors or the like.

The control device100collectively includes hardware and software constituting a process execution unit that executes various processes, a determination unit that determines satisfaction or dissatisfaction of various conditions, an arithmetic unit that performs various computations, and the like.

The control device100collectively includes, for example, a process execution unit100athat executes a foreign matter cleaning process of removing foreign matter accumulated in the circulation path140of the heat exchanger body14and cleaning the circulation path140. The foreign matter cleaning process is a process of generating gas bubbles of the coolant and removing the foreign matter accumulated in the circulation path140by a force generated when a volume change of the gas bubbles or disappearance of the gas bubbles occurs.

Furthermore, the control device100collectively includes an arithmetic unit100bthat calculates a blockage degree OD of the circulation path140and the like. The blockage degree OD is an index for clogging of the circulation path140. The blockage degree OD is set to have a minimum value (e.g., 0%) when no foreign matter is accumulated and have a maximum value (e.g., 100%) when the circulation path140is completely blocked by foreign matter or the like.

Furthermore, the control device100collectively includes an accumulation determination unit100cthat determines whether a foreign matter accumulation condition is fulfilled that is satisfied when foreign matter is expected to be accumulated in at least a part of the circulation path140. The foreign matter accumulation condition of the present embodiment is a condition that is satisfied when the blockage degree OD exceeds a predetermined blockage threshold ODth1.

Next, operation of the heat exchanger1of the present embodiment will be described. In the heat exchanger1, for example, when the vehicle is started and heat is generated by the electronic component20, the control device100drives the circulation pump12to execute a cooling process for the electronic component20. As shown inFIG.2, the coolant discharged from the circulation pump12flows into the circulation path140of the heat exchanger body14. At this time, heat of the electronic component20is transferred to the coolant flowing through the circulation path140to cool the electronic component20. The coolant flowing out of the circulation path140of the heat exchanger body14radiates heat to outside air in the radiator16, and is then sucked into the circulation pump12.

The temperature of the coolant flowing through the circulation path140is increased by heat from the electronic component20. When the electronic component20is at high temperature, in some cases, the temperature of the coolant is increased close to a saturation temperature Ts. According to research and study by the inventors, when the temperature of the coolant is increased close to the saturation temperature Ts, in some cases, a part of the anticorrosive or impurities in the water contained in the coolant are deteriorated and solidified, and the solidified substance is accumulated as foreign matter on a wall surface of the circulation path140as shown inFIG.3. Such a phenomenon presumably occurs because the components constituting the coolant are locally concentrated around gas bubbles generated by boiling, and a hydrogen ion exponent pH is increased, resulting in precipitation of foreign matter derived from the anticorrosive or the impurities in the water. Such foreign matter is mainly accumulated in a heat exchange section of the heat exchanger body14. Unlike the case of foreign matter entering from outside, it is difficult to predict a part of the heat exchange section of the heat exchanger body14at which such foreign matter is accumulated. Thus, for example, even if a filter for capturing the foreign matter is placed on a coolant flow upstream side in the heat exchange section of the heat exchanger body14, it is difficult to achieve an effect of capturing the foreign matter by the filter. Accumulation as the foreign matter of the solidified anticorrosive or impurities in the water of the antifreeze has been found as a result of the study by the inventors.

When foreign matter is accumulated in the circulation path140, the accumulated foreign matter serves as a thermal resistance that hinders heat transfer between the coolant and the electronic component20, and deteriorates the cooling performance for the electronic component20. When foreign matter is accumulated in the circulation path140, fine irregularities formed on an inner wall of the circulation path140are smoothed by the foreign matter, and thus a heat transfer area between the coolant and the electronic component20is reduced. This is also a factor that deteriorates the cooling performance for the electronic component20.

In this regard, the heat exchanger1is configured such that the control device100executes a control process including the foreign matter cleaning process. An example of the control process executed by the control device100will be described below with reference to a flow chart shown inFIG.4. The control process shown inFIG.4is executed by the control device100at regular or irregular intervals, for example, after the vehicle is started. Control steps of the control process shown inFIG.4constitute a function implementation unit that implements various functions implemented by the control device100.

As shown inFIG.4, at step S100, the control device100acquires various signals from various sensors, the vehicle control device120, or the like. Then, at step S110, the control device100calculates the blockage degree OD of the circulation path140of the heat exchanger body14.

In the heat exchanger body14, when the blockage degree OD of the circulation path140is increased by foreign matter, the flow rate Gr of the coolant flowing into the heat exchanger body14is reduced, and the pressure loss ΔP of the heat exchanger body14is increased. Accordingly, the blockage degree OD of the circulation path140is highly correlated with the flow rate Gr of the coolant and the pressure loss ΔP.

Thus, as shown inFIG.5, the control device100is configured such that the arithmetic unit100bcalculates the blockage degree OD of the circulation path140on the basis of the flow rate Gr of the coolant flowing into the heat exchanger body14and the pressure loss ΔP of the heat exchanger body14. The arithmetic unit100brefers to, for example, a control map that defines a correspondence between the flow rate Gr of the coolant, the pressure loss ΔP, and the blockage degree OD, and calculates the blockage degree OD on the basis of a detection value obtained by the flow rate sensor101and a detection value obtained by the differential pressure sensor102. The arithmetic unit100bmay be configured to calculate the blockage degree OD, for example, by using a function that defines, as a mathematical expression, the correspondence between the flow rate Gr of the coolant, the pressure loss ΔP, and the blockage degree OD.

Returning toFIG.4, at step S120, the control device100determines whether the blockage degree OD exceeds the predetermined blockage threshold ODth1. The blockage threshold ODth1is set in advance to a value that ensures the cooling performance of the heat exchanger body14for the electronic component20. The blockage threshold ODth1is not limited to a fixed value set in advance, and may be, for example, a variable value that is successively changed.

When the blockage degree OD is the blockage threshold ODth1or less, there is not much foreign matter accumulated in the circulation path140, and presumably, the heat exchanger body14can sufficiently cool the electronic component20. Thus, at step S130, the control device100executes the cooling process for the electronic component20. In the cooling process, the control device100controls the circulation pump12so that a pump rotational speed N of the circulation pump12is a normal rotational speed Nn.

On the other hand, when the blockage degree OD exceeds the blockage threshold ODth1, foreign matter is accumulated in the circulation path140, and the cooling performance of the heat exchanger body14for the electronic component20may be deteriorated. Thus, control proceeds to step S140, and the control device100executes the foreign matter cleaning process of removing the foreign matter accumulated in the circulation path140. Details of the foreign matter cleaning process will be described with reference to a flow chart shown inFIG.6.

As shown inFIG.6, first, at step S141, the control device100calculates a superheating degree ΔT of the coolant flowing through the circulation path140. The superheating degree ΔT of the coolant is a temperature difference between a temperature of a heat transfer portion between the coolant and the electronic component20and the saturation temperature Ts of the coolant.

The temperature of the heat transfer portion between the coolant and the electronic component20is correlated with the device temperature Td of the electronic component20. The saturation temperature Ts of the coolant is correlated with the coolant temperature Tw, which is the temperature of the coolant flowing into the heat exchanger body14. Accordingly, the superheating degree ΔT of the coolant is correlated with the device temperature Td and the coolant temperature Tw.

Thus, as shown inFIG.7, the control device100is configured such that the arithmetic unit100bcalculates the superheating degree ΔT of the coolant on the basis of the device temperature Td of the electronic component20and the coolant temperature Tw, which is the temperature of the coolant flowing into the heat exchanger body14. The arithmetic unit100brefers to, for example, a control map that defines a correspondence between the device temperature Td, the coolant temperature Tw, and the superheating degree ΔT, and calculates the superheating degree ΔT of the coolant on the basis of a detection value obtained by the device temperature sensor104and a detection value obtained by the coolant temperature sensor103. The arithmetic unit100bmay be configured to calculate the superheating degree ΔT of the coolant, for example, by using a function that defines, as a mathematical expression, the correspondence between the device temperature Td, the coolant temperature Tw, and the superheating degree ΔT.

Subsequently, at step S142, the control device100sets a target superheating degree ΔTtr. The target superheating degree ΔTtr is a target value of the superheating degree ΔT of the coolant during execution of the foreign matter cleaning process, and is set to a value within a nucleate boiling region.

FIG.8shows a boiling curve indicating a form of boiling phenomenon of the coolant as a relationship between the superheating degree ΔT of the coolant and a heat transfer coefficient H of the heat transfer portion between the coolant and the electronic component20. As shown inFIG.8, in a non-boiling region in which the superheating degree ΔT of the coolant is less than a saturation start point ΔTs, the coolant does not boil and heat is transferred by natural convection. The saturation start point ΔTs is the superheating degree at which generation of gas bubbles of the coolant is started.

In the nucleate boiling region in which the superheating degree ΔT of the coolant exceeds the saturation start point ΔTs, boiling is started and heat flux is increased, and thus the heat transfer coefficient H is increased. In the nucleate boiling region, as the superheating degree ΔT is increased, the heat transfer coefficient H is increased. The nucleate boiling region is a region in which the superheating degree ΔT of the coolant ranges from the saturation start point ΔTs to a burnout point ΔTm. The burnout point ΔTm is the superheating degree at which the heat transfer coefficient H is maximum in the nucleate boiling region.

In a film boiling region in which the superheating degree ΔT of the coolant exceeds the burnout point ΔTm, a vapor film is formed in the vicinity of the heat transfer portion between the coolant and the electronic component20. Thus, in the film boiling region, the vapor film formed in the vicinity of the heat transfer portion serves as a thermal resistance that hinders heat exchange between the coolant and the electronic component20, and the heat transfer coefficient H is reduced. In the film boiling region, generation of gas bubbles in the vicinity of the heat transfer portion is prevented, and thus the foreign matter is less likely to be removed than in the nucleate boiling region.

In the nucleate boiling region, a gradient of the heat transfer coefficient H is maximum in the vicinity of an intermediate point ΔTc between the saturation start point ΔTs and the burnout point ΔTm. In the present embodiment, in the nucleate boiling region, a region from the saturation start point ΔTs to the intermediate point ΔTc is referred to as a low superheating degree region, and a region from the intermediate point ΔTc to the burnout point ΔTm is referred to as a high superheating degree region. The high superheating degree region is also a region in which the superheating degree is closer to the burnout point ΔTm than to the saturation start point ΔTs.

In the nucleate boiling region, when the superheating degree ΔT of the coolant is in the high superheating degree region in which the superheating degree is closer to the burnout point ΔTm than to the saturation start point ΔTs, due to an increase in the number of points at which gas bubbles are generated or the like, a force generated when a volume change of the gas bubbles or disappearance of the gas bubbles occurs tends to be larger than in the low superheating degree region. Thus, in the high superheating degree region, the foreign matter is presumably more likely to be removed than in the low superheating degree region.

Thus, the control device100sets, as the target superheating degree ΔTtr, a superheating degree in the high superheating degree region. For example, the target superheating degree ΔTtr is set to be higher as the blockage degree OD is higher. The target superheating degree ΔTtr may be a fixed value determined in advance instead of a variable value.

Subsequently, at step S143, the control device100reduces the amount of coolant supplied from the circulation pump12to the heat exchanger body14so that the coolant has a superheating degree in the nucleate boiling region. Thus, as shown inFIG.9, the control device100controls operation of the circulation pump12so that the pump rotational speed N of the circulation pump12is a pump rotational speed Nc which is lower than the pump rotational speed Nn during the cooling process.

The control device100of the present embodiment sets, as the target superheating degree ΔTtr, a superheating degree closer to the burnout point ΔTm than to the saturation start point ΔTs, and reduces the amount of coolant supplied from the circulation pump12to the heat exchanger body14so that the superheating degree ΔT of the coolant approaches the target superheating degree ΔTtr. Specifically, the control device100reduces the pump rotational speed N of the circulation pump12by feedback control so that the superheating degree ΔT of the coolant approaches the target superheating degree ΔTtr.

When the amount of coolant supplied to the heat exchanger body14is reduced, the temperature of the heat transfer portion between the coolant and the electronic component20is increased. Then, when the superheating degree ΔT reaches the nucleate boiling region, as shown inFIG.10, gas bubbles are generated in the circulation path140, and the foreign matter accumulated in the circulation path140is removed by a force generated when a volume change of the gas bubbles or disappearance of the gas bubbles occurs.

Returning toFIG.4, at step S150, the control device100acquires again a detection value obtained by the flow rate sensor101, a detection value obtained by the differential pressure sensor102, and the like, and calculates the blockage degree OD on the basis of the acquired information. At step S150, the blockage degree OD is calculated by the same method as in step S110. Thus, the method of calculating the blockage degree OD at step S150will not be described.

Subsequently, at step S160, the control device100determines whether the blockage degree OD of the coolant exceeds a predetermined release threshold ODth2. The release threshold ODth2is set to a value lower than the blockage threshold ODth1. For example, the release threshold ODth2is set to a value obtained by subtracting a predetermined value a from the blockage threshold ODth1as expressed by the following formula F1.
ODth2=ODth1−α  (F1)

When the blockage degree OD exceeds the predetermined release threshold ODth2, the removal of the foreign matter is presumably incomplete. Thus, when the blockage degree OD exceeds the predetermined release threshold ODth2, control returns to step S140and the control device100continues the foreign matter cleaning process.

On the other hand, when the blockage degree OD is the predetermined release threshold ODth2or less, the removal of the foreign matter is presumably complete. Thus, when the blockage degree OD is the predetermined release threshold ODth2or less, control proceeds to step S130and the control device100executes the cooling process for the electronic component20.

In the present embodiment, a configuration that executes the determination process at step S120constitutes the accumulation determination unit100cthat determines satisfaction or dissatisfaction of the foreign matter accumulation condition. The foreign matter accumulation condition is a condition that is satisfied when the blockage degree OD exceeds the blockage threshold ODth1.

In the present embodiment, a configuration that executes the process at step S140constitutes the process execution unit100athat executes the foreign matter cleaning process, and a configuration that executes the process at step S141, and the like constitute the arithmetic unit100bthat calculates the blockage degree OD of the circulation path140.

The heat exchanger1described above is configured such that when foreign matter is expected to be accumulated in at least a part of the circulation path140of the heat exchanger body14, the amount of coolant supplied to the heat exchanger body14is reduced so that the coolant has a superheating degree ΔT in the nucleate boiling region. According to this, the foreign matter accumulated in the circulation path140can be removed by a force generated at the time of occurrence of a volume change or disappearance of the gas bubbles generated in the circulation path140. Such a configuration does not require a dedicated device such as an ultrasonic wave generation unit, leading to simplification of the heat exchanger1. Thus, the heat exchanger1of the present embodiment can remove the foreign matter accumulated in the circulation path140and clean the circulation path140with a simple configuration.

FIG.11shows the result of comparison between the heat transfer coefficient H of the heat exchanger1of the present embodiment and the heat transfer coefficient H of a heat exchange device of a comparative example of the present embodiment when the heat exchanger body14is used for a predetermined period. The heat exchange device of the comparative example differs from the heat exchange device of the present embodiment in that the foreign matter cleaning process is not executed. According toFIG.11, the heat transfer coefficient H of the heat exchanger1of the present embodiment is higher by approximately 15% than the heat transfer coefficient H of the heat exchange device of the comparative example. This shows that since the foreign matter in the circulation path140is cleaned off by the foreign matter cleaning process, the cooling performance of the heat exchanger body14is improved.

In the foreign matter cleaning process, the heat exchanger1of the present embodiment sets, as the target superheating degree ΔTtr, a superheating degree ΔT closer to the burnout point ΔTm than to the saturation start point ΔTs, and operates the circulation pump12so that the superheating degree ΔT of the coolant approaches the target superheating degree ΔTm. According to this, a large force is generated when a volume change of the gas bubbles or disappearance of the gas bubbles occurs, and thus the foreign matter accumulated in the circulation path140is easily removed.

The heat exchanger1of the present embodiment is configured to calculate the blockage degree OD of the circulation path140from the flow rate Gr of the coolant and the pressure loss ΔP and execute the foreign matter cleaning process when the blockage degree OD exceeds the blockage threshold ODth1. According to this, the foreign matter cleaning process can be executed while the foreign matter is accumulated in the circulation path140. In other words, since the foreign matter cleaning process is not executed while no foreign matter is accumulated, unnecessary execution of the foreign matter cleaning process can be prevented.

The heat exchanger body14of the present embodiment is composed of a component cooler that is configured to cool, as the cooled object, the electronic component20generating heat by energization and cools the electronic component20by heat exchange between the electronic component20and the coolant. According to this, insufficient cooling of the electronic component20due to the accumulation of foreign matter in the circulation path140of the heat exchanger body14can be prevented with a simple configuration.

In particular, in the present embodiment, the electronic component20is composed of a SiC semiconductor device having better performance characteristics at high temperature than other semiconductor devices. According to this, even if the cooling performance of the heat exchanger body14is slightly deteriorated by the foreign matter cleaning process, operation of the electronic component20can be continued.

Modification of the First Embodiment

The first embodiment shows an example in which the cooling process for the electronic component20is executed when, after the foreign matter cleaning process is executed, the blockage degree OD is the predetermined release threshold ODth2or less, but the present disclosure is not limited to this. The heat exchanger1may be configured to execute the cooling process for the electronic component20, for example, when, after the foreign matter cleaning process is executed, a predetermined time has elapsed from the start of the foreign matter cleaning process.

Second Embodiment

Next, the heat exchanger1of a second embodiment will be described with reference toFIGS.12and13. The present embodiment differs from the first embodiment in the method of calculating the blockage degree OD. In the present embodiment, portions different from those of the first embodiment will be mainly described, and the same portions as in the first embodiment may not be described.

As shown inFIG.12, in the heat exchanger1, the differential pressure sensor102for detecting the pressure loss ΔP of the heat exchanger body14is omitted. That is, the heat exchanger1is provided with only the flow rate sensor101, the coolant temperature sensor103, and the like, and is not provided with the differential pressure sensor102.

As shown inFIG.13, the arithmetic unit100bof the control device100is configured to calculate the blockage degree OD of the circulation path140on the basis of a detection value obtained by the flow rate sensor101. Specifically, the arithmetic unit100brefers to, for example, a control map that defines a correspondence between the flow rate Gr of the coolant and the blockage degree OD, and calculates the blockage degree OD on the basis of a detection value obtained by the flow rate sensor101. The arithmetic unit100bmay be configured to calculate the blockage degree OD, for example, by using a function that defines, as a mathematical expression, the correspondence between the flow rate Gr of the coolant and the blockage degree OD.

The heat exchanger1of the present embodiment differs from the heat exchanger1of the first embodiment in the method of calculating the blockage degree OD, but the rest of the configuration and operation is the same as in the first embodiment. Thus, as in the first embodiment, the heat exchanger1of the present embodiment can achieve the same functions and effects achieved by the same configuration and operation as in the first embodiment.

In particular, the heat exchanger1of the present embodiment does not use the differential pressure sensor102to detect the blockage degree OD, and thus has an advantage that the foreign matter accumulated in the circulation path140can be cleaned off with a simplified configuration.

Modification of the Second Embodiment

The second embodiment shows an example in which the blockage degree OD of the circulation path140is calculated on the basis of a detection value obtained by the flow rate sensor101, but the present disclosure is not limited to this. The heat exchanger1may be configured to calculate the blockage degree OD, for example, on the basis of the pressure loss ΔP of the heat exchanger body14. In this case, the heat exchanger1includes the differential pressure sensor102but does not need to include the flow rate sensor101, and thus the foreign matter accumulated in the circulation path140can be cleaned off with a simplified configuration.

The heat exchanger1may be configured to calculate the blockage degree OD, for example, by taking into consideration not only the flow rate Gr of the coolant and the pressure loss ΔP but also the period of use of the heat exchanger body14, the pump rotational speed N, and the coolant temperature Tw.

Third Embodiment

Next, the heat exchanger1of a third embodiment will be described with reference toFIGS.14to16. The present embodiment differs from the first embodiment in that elapsed time Tv from the start of use of the heat exchanger body14or the like is a factor that determines satisfaction or dissatisfaction of the foreign matter accumulation condition. In the present embodiment, portions different from those of the first embodiment will be mainly described, and the same portions as in the first embodiment may not be described.

The heat exchanger1of the present embodiment is configured such that the control device100can measure elapsed time from the start of use of the heat exchanger body14or elapsed time from the previous foreign matter cleaning process. Specifically, as shown inFIG.14, the control device100aggregates a timer unit100dfor measuring the elapsed time Tv from the start of use of the heat exchanger body14or elapsed time Tv from the previous foreign matter cleaning process. The timer unit100dis implemented by hardware and software constituting the control device100.

According to findings by the inventors, foreign matter tends to be more likely to be accumulated in the circulation path140as the elapsed time Tv from the start of use of the heat exchanger body14or the elapsed time Tv from the previous foreign matter cleaning process is increased.

Thus, the control device100of the present embodiment is configured to execute the foreign matter cleaning process on the basis of not the blockage degree OD of the circulation path140but the elapsed time Tv from the start of use of the heat exchanger body14or the elapsed time Tv from the previous foreign matter cleaning process. Since the blockage degree OD of the circulation path140does not need to be calculated, the heat exchanger1of the present embodiment is not provided with the flow rate sensor101or the differential pressure sensor102.

An example of the control process executed by the control device100of the present embodiment will be described below with reference toFIG.15. The control process shown inFIG.15is executed by the control device100at regular or irregular intervals, for example, after the vehicle is started. Control steps of the control process shown inFIG.15constitute the function implementation unit that implements various functions implemented by the control device100.

As shown inFIG.15, at step S100, the control device100acquires various signals from various sensors, the vehicle control device120, or the like. Then, at step S170, the control device100operates the timer unit100dto measure the elapsed time Tv from the start of use of the heat exchanger body14or the elapsed time Tv from the previous foreign matter cleaning process. Then, at step S180, the control device100determines whether the elapsed time Tv exceeds a predetermined reference time Tvth. In the present embodiment, a configuration that executes the determination process at step S170constitutes the accumulation determination unit100cthat determines satisfaction or dissatisfaction of the foreign matter accumulation condition. The foreign matter accumulation condition is a condition that is satisfied when the elapsed time Tv from the start of use of the heat exchanger body14or the elapsed time Tv from the previous foreign matter cleaning process exceeds the predetermined reference time Tvth.

Depending on the use mode of the devices or the like of the heat exchanger1, even when the elapsed time Tv from the start of use of the heat exchanger body14or the like is short, foreign matter may be accumulated in the circulation path140. For example, when the circulation pump12is operated at low capacity or when the temperature of the coolant flowing into the circulation path140is continuously high, foreign matter may be accumulated in the circulation path140in a short period of time.

Thus, the reference time Tvth serving as a determination threshold of the foreign matter accumulation condition is a variable threshold that is variable according to an operating state of the circulation pump12or a change in the temperature of the coolant. Specifically, as shown inFIG.16, the control device100is configured such that the arithmetic unit100bsets the reference time Tvth on the basis of the pump rotational speed N of the circulation pump12and the coolant temperature Tw. The arithmetic unit100bsets the reference time Tvth to a short time, for example, when the circulation pump12is continuously operated at low capacity or when the temperature of the coolant flowing into the circulation path140is continuously high. The arithmetic unit100bsets the reference time Tvth to a long time, for example, when the circulation pump12is continuously operated at high capacity or when the temperature of the coolant flowing into the circulation path is continuously low.

Returning toFIG.15, when the elapsed time Tv is the reference time Tvth or less, there is not much foreign matter accumulated in the circulation path140, and presumably, the heat exchanger body14can sufficiently cool the electronic component20. Thus, at step S130, the control device100executes the cooling process for the electronic component20. This cooling process is the same as the cooling process described in the first embodiment.

On the other hand, when the elapsed time Tv exceeds the reference time Tvth, foreign matter is likely to be accumulated in the circulation path140, and the cooling performance of the heat exchanger body14for the electronic component20may be deteriorated. Thus, control proceeds to step S140, and the control device100executes the foreign matter cleaning process of removing the foreign matter accumulated in the circulation path140. This foreign matter cleaning process is basically the same as the foreign matter cleaning process described in the first embodiment. However, the control device100of the present embodiment is configured to continue the foreign matter cleaning process until time required to remove the foreign matter has elapsed.

When the foreign matter cleaning process at step S140ends, control proceeds to step S190and the control device100executes a timer reset process. In this process, the time measured by the timer unit100dis reset.

The heat exchanger1of the present embodiment differs from the heat exchanger1of the first embodiment in the content of the process of determining satisfaction or dissatisfaction of the foreign matter accumulation condition, but the rest of the configuration and operation is the same as in the first embodiment. Thus, as in the first embodiment, the heat exchanger1of the present embodiment can achieve the same functions and effects achieved by the same configuration and operation as in the first embodiment.

The heat exchanger1of the present embodiment is configured to execute the foreign matter cleaning process when the elapsed time Tv from the start of use of the heat exchanger body14or the like exceeds the reference time Tvth. According to this, the foreign matter cleaning process can be executed while the foreign matter is accumulated in the circulation path140. In other words, since the foreign matter cleaning process is not executed while no foreign matter is accumulated, an unnecessary performance of a foreign matter cleaning process can be prevented.

In particular, since the blockage degree OD of the circulation path140does not need to be calculated, the heat exchanger1of the present embodiment does not need to include the flow rate sensor101or the differential pressure sensor102. Thus, the foreign matter accumulated in the circulation path140can be removed with a simpler configuration.

Modification of the Third Embodiment

The third embodiment shows an example in which the reference time Tvth serving as the determination threshold of the foreign matter accumulation condition is a variable threshold, but the present disclosure is not limited to this. The reference time Tvth may be, for example, a fixed threshold.

The third embodiment shows an example in which the foreign matter accumulation condition is a condition that is satisfied when the elapsed time Tv exceeds the predetermined reference time Tvth, but the present disclosure is not limited to this. The foreign matter accumulation condition may be, for example, a condition that is satisfied when the elapsed time Tv exceeds the predetermined reference time Tvth or when the blockage degree OD exceeds the blockage threshold ODth1. That is, the foreign matter accumulation condition may be a condition that is determined to be satisfied by taking into consideration both the elapsed time Tv and the blockage degree OD.

Fourth Embodiment

Next, a fourth embodiment will be described with reference toFIGS.17to19. The present embodiment differs from the first embodiment in that the foreign matter cleaning process is executed by taking into consideration not only satisfaction or dissatisfaction of the foreign matter accumulation condition but also satisfaction or dissatisfaction of a low load condition. In the present embodiment, portions different from those of the first embodiment will be mainly described, and the same portions as in the first embodiment may not be described.

The heat exchanger1of the present embodiment is configured such that the control device100can determine satisfaction or dissatisfaction of the low load condition that is satisfied when a load on a device (e.g., inverter) including the electronic component20which is the cooled object is expected to be lower than a predetermined reference load. Specifically, as shown inFIG.17, the control device100collectively includes a load determination unit100efor determining satisfaction or dissatisfaction of the low load condition. The load determination unit100eis implemented by hardware and software constituting the control device100.

When the load on the device including the electronic component20which is the cooled object is high, a large amount of heat is expected to be generated by the cooled object, and thus higher priority needs to be placed on cooling of the cooled object than on foreign matter cleaning. Thus, the control device100of the present embodiment is configured to execute the foreign matter cleaning process in response to both the foreign matter accumulation condition and the low load satisfaction condition being satisfied.

An example of the control process executed by the control device100of the present embodiment will be described below with reference toFIG.18. The control process shown inFIG.18is executed by the control device100at regular or irregular intervals, for example, after the vehicle is started. The processes at steps S100to S160shown inFIG.18are the same as the processes at steps S100to S160of the control process shown inFIG.4, and thus will not be described again.

As shown inFIG.18, when it is determined in the determination process at step S120that the blockage degree OD exceeds the blockage threshold ODth1, at step S200, the control device100determines whether the low load condition is satisfied. Then, when the low load condition is not satisfied, at step S130, the control device100executes the cooling process. On the other hand, when the low load condition is satisfied, at step S140, the control device100executes the foreign matter cleaning process.

When the load on the device including the electronic component20which is the cooled object is low, a small amount of heat is generated by the cooled object and a small amount of heat is received by the coolant, and thus in many cases, the coolant temperature Tw is presumably the saturation temperature Ts or less. Accordingly, the low load condition is a condition that is satisfied when the coolant temperature Tw immediately before execution of the foreign matter cleaning process is the saturation temperature Ts or less. The determination process of determining satisfaction or dissatisfaction of the low load condition executed by the control device100will be described below with reference toFIG.19.

As shown inFIG.19, at step S201, the control device100determines whether the coolant temperature Tw is the saturation temperature Ts set in advance or less. Then, when the coolant temperature Tw is the saturation temperature Ts or less, the control device100determines that the low load condition is satisfied. On the other hand, when the coolant temperature Tw exceeds the saturation temperature Ts, the control device100determines that the low load condition is not satisfied.

In the present embodiment, a configuration that executes the determination process at step S200constitutes the load determination unit100ethat determines satisfaction or dissatisfaction of the low load condition. The low load condition is a condition that is satisfied when the coolant temperature Tw immediately before execution of the foreign matter cleaning process is the saturation temperature Ts or less.

As described above, the heat exchanger1of the present embodiment differs from the heat exchanger1of the first embodiment in that the determination process of determining satisfaction or dissatisfaction of the low load condition is added, but the rest of the configuration and operation is the same as in the first embodiment. Thus, as in the first embodiment, the heat exchanger1of the present embodiment can achieve the same functions and effects achieved by the same configuration and operation as in the first embodiment.

The heat exchanger1of the present embodiment is configured to execute the foreign matter cleaning process when the foreign matter accumulation condition is satisfied and the low load condition is satisfied. According to this, when the load on the device including the electronic component20which is the cooled object is high, higher priority is placed on cooling of the cooled object than on foreign matter cleaning, leading to sufficient protection of the cooled object.

Modification of the Fourth Embodiment

The fourth embodiment shows an example in which the low load condition is a condition that is satisfied when the coolant temperature Tw is the saturation temperature Ts or less, but the present disclosure is not limited to this. The low load condition may be, for example, a condition that is satisfied at the time of executing a process of stopping the device including the electronic component20(e.g., a drive stop process for the vehicle) or at the time when the device including the electronic component20is in an idle state (e.g., an idle state of the vehicle). The time of executing the process of stopping the device including the electronic component20and the idle state of the device including the electronic component20can be determined on the basis of the information acquired from the vehicle control device120. The low load condition may be a condition that is satisfied at the time of executing an excessive discharge process executed during maintenance of the vehicle, or the like.

the fourth embodiment shows an example in which the determination process of determining satisfaction or dissatisfaction of the low load condition is added to the control process described in the first embodiment, but the present disclosure is not limited to this. The determination process of determining satisfaction or dissatisfaction of the low load condition may be added, for example, to the control process described in the third embodiment.

Fifth Embodiment

Next, the heat exchanger1of a fifth embodiment will be described with reference toFIG.20. The present embodiment differs from the fourth embodiment in that the determination process of determining satisfaction or dissatisfaction of the low load condition is executed prior to the determination process of determining satisfaction or dissatisfaction of the foreign matter accumulation condition. In the present embodiment, portions different from those of the fourth embodiment will be mainly described, and the same portions as in the fourth embodiment may not be described.

As shown inFIG.20, at step S100, the control device100acquires various signals from various sensors, the vehicle control device120, or the like, then at step S200, the control device100determines whether the low load condition is satisfied. Then, when the low load condition is not satisfied, at step S130, the control device100executes the cooling process. On the other hand, when the low load condition is satisfied, at step S110, the control device100calculates the blockage degree OD of the circulation path140.

As described above, the heat exchanger1of the present embodiment differs from the heat exchanger1of the fourth embodiment in that the determination process of determining satisfaction or dissatisfaction of the low load condition is executed prior to the determination process of determining satisfaction or dissatisfaction of the foreign matter accumulation condition, but the rest of the configuration and operation is the same as in the fourth embodiment. Thus, as in the fourth embodiment, the heat exchanger1of the present embodiment can achieve the same functions and effects achieved by the same configuration and operation as in the fourth embodiment.

Sixth Embodiment

Next, the heat exchanger1of a sixth embodiment will be described with reference toFIG.21. The present embodiment differs from the first embodiment in that during execution of the foreign matter cleaning process, the control device100increases the amount of heat generated by the electronic component20. In the present embodiment, portions different from those of the first embodiment will be mainly described, and the same portions as in the first embodiment may not be described.

FIG.21is a flow chart showing an example of the foreign matter cleaning process executed by the control device100of the present embodiment. The processes at steps S141to S143shown inFIG.21are the same as the processes at steps S141to S143of the control process shown inFIG.6, and thus may not be described.

As shown inFIG.21, at step S143, the control device100reduces the pump rotational speed N, and then control proceeds to step S144. Thus, at step S144, the control device100acquires various signals from various sensors, the vehicle control device120, or the like. Then, at step S145, the control device100calculates the superheating degree ΔT of the coolant flowing through the circulation path140. The superheating degree ΔT of the coolant is calculated by the same method as in step S141, and thus will not be described.

Subsequently, at step S146, the control device100determines whether the superheating degree ΔT of the coolant exceeds the saturation start point ΔTs. That is, the control device100determines whether the coolant has a superheating degree in the nucleate boiling region.

Then, when the superheating degree ΔT of the coolant exceeds the saturation start point ΔTs, removal of the foreign matter is presumably possible. Thus, the control device100stops the foreign matter cleaning process without increasing the amount of heat generated by the electronic component20.

On the other hand, when the superheating degree ΔT of the coolant is the saturation start point ΔTs or less, the coolant does not have a superheating degree in the nucleate boiling region, and removal of the foreign matter is presumably difficult. Thus, at step S147, the control device100increases the amount of heat generated by the electronic component20. Specifically, the control device100causes the drive circuit22to increase the energization amount to the electronic component20so that the amount of heat generated by the electronic component20is increased.

As described above, the heat exchanger1of the present embodiment differs from the heat exchanger1of the first embodiment in that during execution of the foreign matter cleaning process, the control device100increases the amount of heat generated by the electronic component20, but the rest of the configuration and operation is the same as in the first embodiment. Thus, as in the first embodiment, the heat exchanger1of the present embodiment can achieve the same functions and effects achieved by the same configuration and operation as in the first embodiment.

In particular, since during execution of the foreign matter cleaning process, the heat exchanger1of the present embodiment increases the amount of heat generated by the electronic component20which is the cooled object, during execution of the foreign matter cleaning process, the temperature of the heat transfer portion between the electronic component20and the coolant is increased. The superheating degree ΔT of the coolant is increased accordingly, and thus the foreign matter accumulated in the circulation path140is easily removed.

Specifically, the heat exchanger1is configured to increase the amount of heat generated by the electronic component20when the adjustment of the amount of coolant supplied from the circulation pump12is insufficient for the coolant to have a superheating degree in the nucleate boiling region. According to this, during execution of the foreign matter cleaning process, the coolant is allowed to have a superheating degree in the nucleate boiling region, and thus the foreign matter accumulated in the circulation path140is easily removed.

Modification of the Sixth Embodiment

The sixth embodiment shows an example in which the amount of heat generated by the electronic component20is increased only when, after the pump rotational speed N of the circulation pump12is reduced in the foreign matter cleaning process, the superheating degree ΔT of the coolant exceeds the saturation start point ΔTs, but the present disclosure is not limited to this.

The heat exchanger1may be configured to increase the amount of heat generated by the electronic component20, for example, regardless of the superheating degree ΔT of the coolant, after the pump rotational speed N of the circulation pump12is reduced in the foreign matter cleaning process. Alternatively, the heat exchanger1may be configured to increase the amount of heat generated by the electronic component20, for example, when, after the pump rotational speed N of the circulation pump12is reduced in the foreign matter cleaning process, the device temperature Td of the electronic component20is a predetermined temperature or less.

When the load on the device including the electronic component20is high, if the amount of heat generated by the electronic component20is increased, there is a possibility that the increase in the amount of heat generated by the electronic component20may significantly influence operation of the device including the electronic component20. Thus, the heat exchanger1is preferably configured to increase the amount of heat generated by the electronic component20, for example, when, after the pump rotational speed N of the circulation pump12is reduced in the foreign matter cleaning process, the low load condition is satisfied.

Seventh Embodiment

Next, the heat exchanger1of a seventh embodiment will be described with reference toFIGS.22to24. The heat exchanger1of the present embodiment differs from the heat exchanger1of the first embodiment in that the cooled object to be cooled by a heat exchanger body14A is supercharged intake air ARc that is supercharged to an internal combustion engine EG by a supercharger SC mounted on the vehicle.

As shown inFIG.22, in the vehicle on which the heat exchanger1is mounted, the supercharger SC is provided in an intake system of the internal combustion engine EG that drives the vehicle. The supercharger SC is provided to improve an output of the internal combustion engine EG by compressing air to be supplied to the internal combustion engine EG and increasing the density of the air.

In the heat exchanger1, the heat exchanger body14A is arranged between the internal combustion engine EG and the supercharger SC in the intake system of the internal combustion engine EG. Specifically, the heat exchanger body14A is composed of an intercooler that is configured to cool, as the cooled object, the supercharged intake air ARc supercharged to the internal combustion engine EG by the supercharger SC and cools the supercharged intake air ARc by heat exchange between the supercharged intake air ARc and the coolant.

The supercharger SC is provided with a drive circuit DC for adjusting air compression capacity. The drive circuit DC can adjust the amount of heat generated by the supercharged intake air ARc compressed by the supercharger SC. In the present embodiment, the drive circuit DC constitutes an adjustment unit that adjusts the amount of heat generated by the supercharged intake air ARc which is the cooled object. The drive circuit DC is configured to be able to change the amount of heat generated by the supercharged intake air ARc according to a control signal from the control device100.

Next, the control device100of the present embodiment will be described. The input side of the control device100is connected to the flow rate sensor101, the differential pressure sensor102, the coolant temperature sensor103, and the like. Furthermore, the control device100is connected to the vehicle control device120so that the control device100can bidirectionally communicate with the vehicle control device120.

The input side of the control device100is connected to an intake air temperature sensor105that detects an intake air temperature Ta, which is a temperature of the supercharged intake air ARc flowing into the heat exchanger body14A. The intake air temperature sensor105is configured to directly detect the intake air temperature Ta. The intake air temperature sensor105is provided to obtain a temperature of a heat transfer portion between the coolant and the supercharged intake air. The intake air temperature Ta detected by the intake air temperature sensor105is used to calculate the superheating degree ΔT of the coolant and the like. The intake air temperature sensor105may be configured to indirectly detect the intake air temperature Ta on the basis of a temperature of the supercharger SC or the like.

On the other hand, the output side of the control device100is connected to the electric motor of the circulation pump12, the drive circuit DC of the supercharger SC, and the like. The control device100controls the electric motor of the circulation pump12, the drive circuit DC of the supercharger SC, and the like on the basis of information acquired from various sensors or the like. The rest of the configuration of the heat exchanger1of the present embodiment is the same as in the first embodiment.

Next, operation of the heat exchanger1of the present embodiment will be described. In the heat exchanger1, for example, when the vehicle is started and the temperature of the supercharged intake air ARc becomes high, the control device100drives the circulation pump12to execute a cooling process for the supercharged intake air ARc. As shown inFIG.23, the coolant discharged from the circulation pump12flows into the circulation path140of the heat exchanger body14A. At this time, heat of the supercharged intake air ARc is transferred to the coolant flowing through the circulation path140to cool the supercharged intake air ARc. The coolant flowing out of the circulation path140of the heat exchanger body14A radiates heat to outside air in the radiator16, and is then sucked into the circulation pump12.

The temperature of the coolant flowing through the circulation path140is increased by heat of the supercharged intake air ARc. When the supercharged intake air ARc is at high temperature, in some cases, the coolant temperature Tw is increased close to the saturation temperature Ts. Then, when the coolant temperature Tw is increased close to the saturation temperature Ts, in some cases, a part of the anticorrosive or impurities in the water contained in the coolant are deteriorated and solidified, and the solidified substance is accumulated as foreign matter in the circulation path140as shown inFIG.24.

Thus, the heat exchanger1of the present embodiment is configured such that the control device100executes a control process including the foreign matter cleaning process. The control process executed by the control device100of the present embodiment is basically the same as the control process described in the first embodiment except that the cooled object is different. Thus, the control process executed by the control device100will not be described.

The heat exchanger1of the present embodiment described above differs from the heat exchanger1of the first embodiment in the cooled object, but has basically the same configuration as in the first embodiment. Thus, as in the first embodiment, the heat exchanger1of the present embodiment can achieve the same functions and effects achieved by the same configuration and operation as in the first embodiment.

In particular, in the heat exchanger1of the present embodiment, the heat exchanger body14A is composed of an intercooler that is configured to cool the supercharged intake air ARc as the cooled object. According to this, insufficient cooling of the supercharged intake air due to the accumulation of foreign matter in the circulation path140of the heat exchanger body14A can be prevented with a simple configuration.

Modification of the Seventh Embodiment

The seventh embodiment shows an example in which the cooled object to be cooled by the heat exchanger body14described in the first embodiment is changed from the electronic component20to the supercharged intake air ARc, but the present disclosure is not limited to this. For example, the heat exchanger1may be configured such that the cooled object to be cooled by the heat exchanger body14described in Embodiments 2 to 6 is changed from the electronic component20to the supercharged intake air ARc. The heat exchanger1may be configured such that in a case where, as in the sixth embodiment, the pump rotational speed N of the circulation pump12is reduced in the foreign matter cleaning process and then the amount of heat generated by the cooled object is increased, the control device100controls the drive circuit DC so that the temperature of the supercharged intake air ARc becomes high.

Other Embodiments

The representative embodiments of the present disclosure have been described, but the present disclosure is not limited to the above embodiments. For example, the present disclosure may be modified in various manners as follows.

The above embodiments show an example in which the heat exchanger1includes the circulation circuit10through which the coolant is circulated, but the present disclosure is not limited to this. For example, the heat exchanger1may be configured to include an open coolant circuit through which the coolant is not circulated.

The above embodiments show an example in which the target superheating degree ΔTtr is set to a superheating degree closer to the burnout point ΔTm than to the saturation start point ΔTs indicated by the boiling curve, but the present disclosure is not limited to this. For example, the heat exchanger1may be configured such that the target superheating degree ΔTtr is set to a superheating degree closer to the saturation start point ΔTs than to the burnout point ΔTm.

The above embodiments show an example in which the coolant is a long-life coolant (i.e., an antifreeze containing an anticorrosive), but the present disclosure is not limited to this. Even when a coolant other than the long-life coolant is used, foreign matter such as oxide may be accumulated inside the heat exchanger body14. Thus, in the heat exchanger1, the coolant may be a liquid fluid other than the long-life coolant.

The above embodiments show an example in which the electronic component20is composed of a SiC semiconductor device, but the present disclosure is not limited to this. The electronic component20may be composed of, for example, a Si semiconductor device.

The above embodiments show an example in which the heat exchanger1is mounted on the vehicle, but the present disclosure is not limited to this. The heat exchanger1does not necessarily need to be mounted on the vehicle, and may be mounted, for example, on a fixed device or the like.

It is unnecessary to say that in the above embodiments, an element constituting the embodiments is not necessarily essential unless the element is explicitly stated to be essential or the element is considered to be apparently essential in principle.

When a numerical value such as the number, numerical value, amount, or range associated with the component of the embodiments is mentioned in the above embodiments, the numerical value is not limited to the specific number unless the specific number is explicitly stated to be essential or the numerical value is obviously limited to the specific number in principle.

When a shape, positional relationship, or the like of the component or the like is mentioned in the above embodiments, the shape, positional relationship, or the like is not limited to the specific shape, positional relationship, or the like unless explicitly stated or the shape, positional relationship, or the like is limited to the specific shape, positional relationship, or the like in principle.

According to the first aspect shown in some or all of the above embodiments, the heat exchange device includes the heat exchanger, the coolant supply pump, the accumulation determination unit that determines satisfaction or dissatisfaction of the foreign matter accumulation condition, and the process execution unit that when the foreign matter accumulation condition is satisfied, executes the foreign matter cleaning process. In the foreign matter cleaning process, the process execution unit reduces the amount of coolant supplied from the coolant supply pump so that the coolant has a superheating degree in the nucleate boiling region.

According to the second aspect, in the foreign matter cleaning process, the process execution unit of the heat exchange device sets, as the target superheating degree in the range from the saturation start point to the burnout point indicated by the boiling curve of the coolant, a superheating degree closer to the burnout point than to the saturation start point. The process execution unit reduces the amount of coolant supplied from the coolant supply pump so that the superheating degree of the coolant approaches the target superheating degree.

When the coolant has a superheating degree closer to the burnout point than to the saturation start point, due to the increase in the number of points at which gas bubbles are generated or the like, a large force is generated when a volume change of the gas bubbles or disappearance of the gas bubbles occurs. Thus, when in the foreign matter cleaning process, the amount of coolant supplied to the heat exchanger is reduced so that the coolant has a superheating degree closer to the burnout point, the foreign matter accumulated in the circulation path is easily removed.

The “saturation start point” is the superheating degree at which generation of gas bubbles of the coolant is started. The “burnout point” is the superheating degree at which the heat transfer coefficient is maximum in the nucleate boiling region.

According to the third aspect, the heat exchange device includes the arithmetic unit that calculates the blockage degree of the circulation path on the basis of at least one of the flow rate of the coolant flowing into the heat exchanger and the pressure loss of the heat exchanger. The foreign matter accumulation condition includes a condition that is satisfied when the blockage degree exceeds the predetermined blockage threshold.

When foreign matter is accumulated in the circulation path and the blockage degree of the circulation path is increased, the flow rate of the coolant flowing into the heat exchanger is reduced, and the pressure loss of the heat exchanger is increased. Accordingly, the blockage degree of the circulation path is highly correlated with the flow rate of the coolant and the pressure loss. Thus, the blockage degree of the circulation path can be determined on the basis of the flow rate of the coolant and the pressure loss. When the blockage degree calculated on the basis of the flow rate of the coolant and the pressure loss is used as a factor that determines satisfaction or dissatisfaction of the foreign matter accumulation condition, the foreign matter cleaning process can be executed while the foreign matter is accumulated in the circulation path. In other words, since the foreign matter cleaning process is not executed while no foreign matter is accumulated, an unnecessary foreign matter cleaning process can be prevented, leading to efficient cooling of the cooled object.

According to the fourth aspect, the foreign matter accumulation condition of the heat exchange device includes a condition that is satisfied when the elapsed time from the start of use of the heat exchanger or the elapsed time from the previous foreign matter cleaning process exceeds the predetermined reference time.

According to findings by the inventors, foreign matter tends to be more likely to be accumulated in the circulation path as the elapsed time from the start of use of the heat exchanger or the elapsed time from the previous foreign matter cleaning process is increased. Thus, when the elapsed time from the start of use of the heat exchanger or the elapsed time from the previous foreign matter cleaning process is used as a factor that determines satisfaction or dissatisfaction of the foreign matter accumulation condition, the foreign matter cleaning process can be executed while the foreign matter is accumulated in the circulation path. In other words, since the foreign matter cleaning process is not executed while no foreign matter is accumulated, an unnecessary foreign matter cleaning process can be prevented, leading to efficient cooling of the cooled object.

Depending on the use mode of the devices or the like of the heat exchange device, even when the elapsed time from the start of use of the heat exchanger or the like is short, foreign matter may be accumulated in the circulation path. For example, when the coolant supply pump is operated at low capacity or when the temperature of the coolant flowing into the circulation path is continuously high, foreign matter may be accumulated in the circulation path in a short period of time.

Thus, the reference time serving as the determination threshold of the foreign matter accumulation condition is preferably a variable threshold that is variable according to an operating state of the coolant supply pump or a change in the temperature of the coolant. As an example of the method of setting the variable threshold, the reference time may be set to a short time when the coolant supply pump is continuously operated at low capacity or when the temperature of the coolant flowing into the circulation path is continuously high. As an example of the method of setting the variable threshold, the reference time may be set to a long time when the coolant supply pump is continuously operated at high capacity or when the temperature of the coolant flowing into the circulation path is continuously low.

According to the fifth aspect, the heat exchange device includes the adjustment unit that adjusts the amount of heat generated by the cooled object. In the foreign matter cleaning process, the process execution unit causes the adjustment unit to increase the amount of heat generated by the cooled object. Thus, when the amount of heat generated by the cooled object is increased during execution of the foreign matter cleaning process, the temperature of the heat transfer portion between the cooled object and the coolant is increased and the superheating degree of the coolant is increased, and thus the foreign matter accumulated in the circulation path is easily removed.

According to the sixth aspect, when, even after the amount of coolant supplied from the coolant supply pump is reduced, the coolant does not have a superheating degree in the nucleate boiling region, the process execution unit of the heat exchange device causes the adjustment unit to increase the amount of heat generated by the cooled object. Thus, with the configuration in which the amount of heat generated by the cooled object is increased when the adjustment of the supply amount of coolant is insufficient for the coolant to have a superheating degree in the nucleate boiling region, the coolant is allowed to have a superheating degree in the nucleate boiling region.

According to the seventh aspect, the heat exchange device includes the load determination unit that determines satisfaction or dissatisfaction of the low load condition that is satisfied when the load on the device including the cooled object is expected to be lower than the predetermined reference load. The process execution unit executes the foreign matter cleaning process when the foreign matter accumulation condition is satisfied and the low load condition is satisfied.

When the load on the device including the cooled object is high, a large amount of heat is expected to be generated by the cooled object, and thus higher priority needs to be placed on cooling of the cooled object than on foreign matter cleaning. Thus, the foreign matter cleaning process is preferably executed when both the foreign matter accumulation condition and the low load satisfaction condition are satisfied.

According to the eighth aspect, the low load condition of the heat exchange device includes a condition that is satisfied when the temperature of the coolant before execution of the foreign matter cleaning process is the saturation temperature or less. When the load on the device including the cooled object is low, a small amount of heat is generated by the cooled object and a small amount of heat is received by the coolant, and thus in many cases, the temperature of the coolant is presumably the saturation temperature or less. Accordingly, the low load condition may be a condition that is satisfied when the temperature of the coolant before execution of the foreign matter cleaning process is the saturation temperature or less.

According to the ninth aspect, the heat exchanger of the heat exchange device is composed of a component cooler that is configured to cool, as the cooled object, an electronic component generating heat by energization and cools the electronic component by heat exchange between the electronic component and the coolant. According to this, insufficient cooling of the electronic component due to the accumulation of foreign matter in the circulation path of the heat exchanger can be prevented with a simple configuration.

According to the tenth aspect, the heat exchanger of the heat exchange device is composed of an intercooler that is configured to cool, as the cooled object, supercharged intake air supercharged to the internal combustion engine by the supercharger and cools the supercharged intake air by heat exchange between the supercharged intake air and the coolant. According to this, insufficient cooling of the supercharged intake air due to the accumulation of foreign matter in the circulation path of the heat exchanger can be prevented with a simple configuration.

According to the eleventh aspect, the coolant used in the heat exchange device is composed of an antifreeze containing an anticorrosive that prevents generation of rust.

The inventors have considered using an antifreeze containing an anticorrosive as the coolant, and cooling the cooled object by the antifreeze. However, in a case where the antifreeze is used as the coolant, when the temperature of the coolant is increased close to the saturation temperature, in some cases, a part of the anticorrosive is deteriorated and solidified, and the solidified substance is accumulated as foreign matter. Unlike the case of foreign matter entering from outside, it is difficult to predict a part of the heat exchanger at which such foreign matter is accumulated, and thus it is difficult to address the foreign matter by using a filter or the like.

In this regard, the heat exchange device of the present disclosure is configured such that the amount of coolant supplied to the heat exchanger is reduced to generate gas bubbles in the circulation path and the gas bubbles are used to remove the foreign matter accumulated in the circulation path, leading to efficient foreign matter cleaning.

Next, eighth to sixteenth embodiments of the heat exchanger of the second aspect of the present disclosure will be described with reference to the drawings. An object of the disclosure is to provide a heat exchanger capable of preventing an imbalance in pressure between a plurality of channels formed by partitioning a channel pipe, thereby improving heat exchanger performance.

In the drawings for explaining the embodiments, unless otherwise specified, arrow X indicates a lamination direction of a plurality of channel pipes constituting the heat exchanger, arrow Y indicates a width direction orthogonal to the lamination direction X, and arrow Z indicates a height direction orthogonal to both the lamination direction X and the width direction Y.

Eighth Embodiment

As shown inFIGS.25and26, a heat exchanger210of an eighth embodiment is used for cooling a plurality of external semiconductor modules201each of which is a heat generating component. Thus, the heat exchanger210can also be referred to as “cooler” or “cooling device”.

The semiconductor module201is an electronic component mounted on a hybrid automobile or the like, and is configured to include an integrated semiconductor device such as an IGBT that converts DC power into AC power. The semiconductor module201has a flat shape. Although not shown in particular, the semiconductor module201includes a power terminal, and a control terminal that is electrically connected to a control circuit board.

The plurality of semiconductor modules201include two first semiconductor modules201A, three second semiconductor modules201B, six third semiconductor modules201C, and three fourth semiconductor modules201D.

The first semiconductor module201A is used as a boosting converter. The second semiconductor module201B is used as an inverter for a motor generator that is driven by an engine (not shown) and operated as an engine starting motor. The third semiconductor module201C is used as an inverter for a motor generator that drives front wheels (not shown) as main drive wheels. The fourth semiconductor module201D is used as an inverter for a motor generator that drives rear wheels (not shown) as driven wheels. The plurality of semiconductor modules201are integrally assembled to the heat exchanger210to form a heat exchange unit.

The applications and the number of the semiconductor modules201are not limited to these, and may be appropriately changed as necessary. According to the number of semiconductor modules201and other conditions, the number of channel pipes220is appropriately set.

The heat exchanger210includes the plurality of channel pipes220, an inflow header unit230through which a heat transfer medium C flows in an inflow direction D1, and an outflow header unit240through which the heat transfer medium C flows in an outflow direction D3. These components of the heat exchanger210are preferably made of a material having good thermal conductivity such as aluminum.

The channel pipe220is configured as a flat-shaped pipe whose thickness direction is the lamination direction X and whose longitudinal direction is the width direction Y. The plurality of channel pipes220are laminated at equal intervals and separated from each other with a space213for sandwiching the semiconductor module201from both sides. Thus, the semiconductor module201inserted into the space213is cooled by the flows of heat transfer medium C through the respective two channel pipes220on both sides in the lamination direction X.

Examples of the heat transfer medium C flowing through the channel pipe220include cooling media such as natural coolants such as water and ammonia, fluorocarbon coolants such as water mixed with an ethylene glycol antifreeze, and Fluorinert (registered trademark), chlorofluorocarbon coolants such as HCFC123 and HFC134a, alcohol coolants such as methanol and alcohol, and ketone coolants such as acetone.

The inflow header unit230and the outflow header unit240are both configured as pipes whose longitudinal direction is the lamination direction X and that are separated from each other in the width direction Y and extend parallel to each other.

The inflow header unit230is connected to an inlet pipe211into which the heat transfer medium C flows. A connection pipe231between the inflow header unit230and the inlet pipe211is provided on one of both end surfaces in the lamination direction X of the plurality of channel pipes220. The inflow header unit230communicates with an inlet opening of each of the plurality of channel pipes220.

The outflow header unit240is connected to an outlet pipe212out of which the heat transfer medium C flows. A connection pipe241between the outflow header unit240and the outlet pipe212is provided on the end surface in the lamination direction X of the plurality of channel pipes220on which the connection pipe231is provided. The outflow header unit240communicates with an outlet opening of each of the plurality of channel pipes220.

Thus, the heat transfer medium C flowing from the inlet pipe211flows in the inflow direction D1through the inflow header unit230and is divided into flows of heat transfer medium in a parallel flow direction D2through the respective plurality of channel pipes220. The flows of heat transfer medium from the respective plurality of channel pipes220are merged in the outflow header unit240. Then, the heat transfer medium flows in the outflow direction D3through the outflow header unit240toward the outlet pipe212, and flows out of the outlet pipe212.

A first channel pipe220A is one of the plurality of channel pipes220that is located at the position closest to the inlet pipe211and the outlet pipe212. A third channel pipe220C is one of the plurality of channel pipes220that is located at the position farthest from the inlet pipe211and the outlet pipe212. A second channel pipe220B is a channel pipe that is located between the channel pipe220A and the channel pipe220C.

As shown inFIG.26, the first channel pipe220A includes a first case member221A and a second case member222A that are arranged to face each other in the lamination direction X, a plate-shaped partition member223that is provided between the first case member221A and the second case member222A, and two internal fins225and226that are arranged on both sides in the lamination direction X with the partition member223interposed therebetween.

The first case member221A is provided with the connection pipe231and the connection pipe241. The second case member222A is provided with a connection pipe232constituting the inflow header unit230and a connection pipe242constituting the outflow header unit240. An outer surface of the second case member222A serves as a heat exchange surface220afor the semiconductor module201.

The first case member221A and the second case member222A are joined to each other by brazing to form a sealed internal space227in which the partition member223is arranged. At this time, the internal space227in the first channel pipe220A is partitioned by the partition member223so that the flows of heat transfer medium C through two channels228and229are parallel to each other.

As shown inFIG.27, the second channel pipe220B includes a first case member221B and a second case member222B that are arranged to face each other in the lamination direction X, and the partition member223and the internal fins225and226that have the same structure as in the first channel pipe220A.

The first case member221B is provided with a connection pipe233constituting the inflow header unit230and a connection pipe243constituting the outflow header unit240. The second case member222B is provided with a connection pipe234constituting the inflow header unit230and a connection pipe244constituting the outflow header unit240. An outer surface of each of the first case member221B and the second case member222B serves as the heat exchange surface220afor the semiconductor module201.

The first case member221B and the second case member222B are joined to each other by brazing to form the sealed internal space227in which the partition member223is arranged. At this time, as in the first channel pipe220A, the internal space227in the second channel pipe220B is partitioned by the partition member223so that the flows of heat transfer medium C through the two channels228and229are parallel to each other.

As shown inFIG.28, the third channel pipe220C includes a first case member221C and a second case member222C that are arranged to face each other in the lamination direction X, and the partition member223and the internal fins225and226that have the same structure as in the first channel pipe220A.

The first case member221C is provided with a connection pipe235constituting the inflow header unit230and a connection pipe245constituting the outflow header unit240. An outer surface of the first case member221C serves as the heat exchange surface220afor the semiconductor module201.

The first case member221C and the second case member222C are joined to each other by brazing to form the sealed internal space227in which the partition member223is arranged. At this time, as in the first channel pipe220A, the internal space227in the third channel pipe220C is partitioned by the partition member223so that the flows of heat transfer medium C through the two channels228and229are parallel to each other.

Internal structures of the three channel pipes220A,220B, and220C will be described below. The channel pipes220A,220B, and220C have the same internal structure, and thus only the internal structure of the second channel pipe220B will be described with reference toFIG.29, and the internal structures of the remaining two channel pipes220A and220C will not be described.

As shown inFIG.29, the two internal fins225and226are both configured such that a cross section in a plane defined by the lamination direction X and the height direction Z has a corrugated shape. Specifically, the internal fin225on the right side inFIG.29has a corrugated cross-sectional shape in which a plurality of convex portions225and a plurality of concave portions225bfacing the partition member223are alternately formed. Similarly, the internal fin226on the left side inFIG.29has a corrugated cross-sectional shape in which a plurality of convex portions226and a plurality of concave portions226bfacing the partition member223are alternately formed.

At each of the plurality of convex portions225a, the internal fin225is joined to a joining portion223aof the partition member223by brazing, and at each of the plurality of concave portions225b, the internal fin225is joined to an inner surface of the first case member221B by brazing. Since the convex portions225aand the concave portions225bof the internal fin225are alternately arranged in the height direction Z, the first channel228formed by partitioning the internal space227by the partition member223is divided into a plurality of narrow channels228aby the internal fin225.

At each of the plurality of convex portions226a, the internal fin226is joined to the joining portion223aof the partition member223by brazing, and at each of the plurality of concave portions226b, the internal fin226is joined to an inner surface of the second case member222B by brazing. Since the convex portions226and the concave portions226bof the internal fin226are alternately arranged in the height direction Z, the second channel229formed by partitioning the internal space227by the partition member223is divided into a plurality of narrow channels229aby the internal fin226.

In the channel228, the heat transfer medium C can be moved between the plurality of narrow channels228a. Thus, the pressure is the same in the plurality of narrow channels228a, and the pressure in the plurality of narrow channels228ais the pressure in the channel228. Similarly, in the channel229, the heat transfer medium C can be moved between the plurality of narrow channels229a. Thus, the pressure is the same in the plurality of narrow channels229a, and the pressure in the plurality of narrow channels229ais the pressure in the channel229.

The partition member223is provided with a plurality of communication holes224spaced from each other in the height direction Z. The plurality of communication holes224are each provided at a non-joining portion223bof the partition member223to which the convex portion225aof the internal fin225or the convex portion226aof the internal fins226is not joined. The communication hole224is configured to pass through the partition member223in the lamination direction X, which is a thickness direction of the partition member223, so that the first channel228and the second channel229communicate with each other. The communication hole224is a through hole having a constant inner diameter in the lamination direction X.

According to this configuration, through the plurality of communication holes224, the heat transfer medium C can be moved between the first channel228and the second channel229. In this case, the communication holes224have a function of preventing an imbalance in the pressure and the flow rate between the first channel228and the second channel229. The number of communication holes224may be appropriately set as necessary.

The plurality of communication holes224are provided at least in a facing region T of the partition member223that faces the semiconductor module201in the lamination direction X. The facing region T is a region in which, due to an influence of heat entering from the semiconductor module201, in particular, an increase in the pressure by boiling of the heat transfer medium C is more likely to occur.

As shown inFIG.30, the communication hole224is configured such that a surface area Sa of an inner peripheral surface224aexceeds twice an opening area Sb of an opening224b(see a hatched region inFIG.30). A longitudinal dimension of the inner peripheral surface224acorresponds to a thickness dimension H of the partition member223, and a lateral dimension of the inner peripheral surface224acorresponds to a circumferential length L of the opening224bof the communication hole224. The opening area Sb corresponds to a surface area of one surface of the partition member223before the communication hole224is provided.

Thus, it can be said that in this configuration, a surface area of the entire partition member223including the surface area Sa of the inner peripheral surface224aof the communication hole224exceeds a surface area of the entire partition member223that is not provided with the communication hole224.

Next, functions and effects of the eighth embodiment will be described.

Heat transfer between the heat transfer medium C of the heat exchanger210and the semiconductor module201will be described, in particular, by using the second channel pipe220B as an example.

As shown inFIG.25, the heat transfer medium C flows from the inflow header unit230into the second channel pipe220B of the heat exchanger210. The heat transfer medium C flowing in the second channel pipe220B exchanges heat with the external semiconductor module201through the heat exchange surfaces220awhich are the outer surfaces on both sides of the second channel pipe220B.

As shown inFIG.29, the second channel pipe220B is partitioned by the plate-shaped partition member223into the first channel228and the second channel229, and the flows of heat transfer medium C through the two channels228and229are parallel to each other in the same parallel flow direction D2(seeFIG.25).

As shown inFIG.31, generated heat Q1from the semiconductor module201on the right side enters the first channel228through the heat exchange surface220aof the first case member221B. Similarly, generated heat Q2from the semiconductor module201on the left side enters the second channel229through the heat exchange surface220aof the second case member222B.

When the heat transfer medium C does not boil either in the first channel228or the second channel229, a pressure P1in the first channel228and a pressure P2in the second channel229have approximately the same value, and a flow rate L1of the heat transfer medium C flowing through the first channel228and a flow rate L2of the heat transfer medium C flowing through the second channel229also have approximately the same value.

On the other hand, when the amount of generated heat Q1exceeds the amount of generated heat Q2and the heat transfer medium C boils only in the first channel228, the pressure P1in the first channel228exceeds the pressure P2in the second channel229, resulting in an imbalance in the pressure. Due to the imbalance in the pressure, an imbalance in the flow rate occurs in which the flow rate L1of the heat transfer medium C in the first channel228is reduced and the flow rate L2of the heat transfer medium C in the second channel229is increased. The imbalance in the flow rate is a factor that deteriorates the heat exchange performance between the semiconductor module201and the heat exchanger210.

In this regard, in the present embodiment, the two channels228and229communicate with each other through the communication hole224provided in the partition member223. Thus, even when an imbalance in the pressure occurs between the two channels228and229, by distributing the pressure so that the pressure P1in the first channel228on the high-pressure side is shared with the second channel229on the low-pressure side through the communication hole224of the partition member223, the imbalance in the pressure can be reduced. When the pressure P1approaches the pressure P2and the imbalance in the pressure is eliminated, the imbalance in the flow rate is reduced and the flow rate L1of the heat transfer medium C in the first channel228is recovered. As a result, as compared with the case where the partition member223is not provided with the communication hole224, the heat exchange performance between the semiconductor module201and the heat exchanger210can be improved.

The disappearance of the imbalance in the pressure using the communication hole224of the partition member223can achieve an effect of protecting the heat exchanger210.

Although not shown in particular, the above description of the second channel pipe220B can be referred to for the first channel pipe220A and the third channel pipe220C. One surface in the lamination direction X of each of the first channel pipe220A and the third channel pipe220C is the heat exchange surface220a. Thus, as compared with the second channel pipe220B having the heat exchange surfaces220aon both sides, in the first channel pipe220A and the third channel pipe220C, the heat transfer medium C is more likely to boil in one of the two channels228and229and an imbalance in the pressure is more likely to occur between the two channels228and229.

In the heat exchanger210, since the heat exchanger210is provided with the internal fin225that divides the channel228into the plurality of narrow channels228and the internal fin226that divides the channel229into the plurality of narrow channels229a, the heat transfer area for heat exchange of the heat transfer medium C is increased and the heat exchange performance is improved.

In the heat exchanger210, since the internal fins225and226having a corrugated cross-sectional shape are used, it is possible to simplify the structure for dividing the two channels228and229into the plurality of narrow channels228and the plurality of narrow channels229a, respectively.

In the heat exchanger210, since the communication hole224is provided at the non-joining portion223bof the partition member223, only the partition member223needs to be processed to have a through hole, leading to easy processing of the communication hole224.

In the heat exchanger210, since the communication hole224is configured such that the surface area Sa of the inner peripheral surface224aexceeds twice the opening area Sb of the opening224b, the surface area of the partition member223can be increased as compared with before the communication hole224is provided. In this case, the surface area of the partition member223serves as the heat transfer area, and thus the heat exchange performance can be improved as compared with the heat exchange performance before the communication hole224is provided.

In the heat exchanger210, since the communication hole224is provided in the region such as the facing region T of the partition member223in which an increase in the pressure by boiling of the heat transfer medium C is more likely to occur, the pressure can be distributed with good responsiveness so that the pressure in the channel on the high-pressure side is shared with the channel on the low-pressure side through the communication hole224.

The communication hole224is not premised on boiling of the heat transfer medium C, and even when the heat transfer medium C does not boil, the communication hole224reliably has the effect of distributing the pressure so that the pressure on the high-pressure side is shared with the low-pressure side.

Other embodiments related to the eighth embodiment will be described below with reference to the drawings. In the other embodiments, the same elements as in the eighth embodiment are given the same reference numerals and are not described.

Ninth Embodiment

As shown inFIG.32, a heat exchanger210A of a ninth embodiment differs from the heat exchanger210of the eighth embodiment in the position of the communication holes224provided in the partition member223of the second channel pipe220B. Although not shown in particular, in the heat exchanger210A, the first channel pipe220A and the third channel pipe220C also have the same structure as the second channel pipe220B.

The communication hole224is provided at the joining portion223aof the partition member223joined to the convex portion225aof the internal fin225and the convex portion226aof the internal fin226, and is not provided at the non-joining portion223bof the internal fin226. Thus, the communication hole224is configured to pass through the partition member223and the two convex portions225and226aon both sides of the partition member223. The joining portion223aat which the communication hole224is provided is a portion at which the introduction of heat from the semiconductor module201is more likely to occur through the convex portion225aof the internal fin225and the convex portion226aof the internal fin226and the heat transfer medium C tends to be generated.

The rest of the configuration is the same as in the eighth embodiment.

In the heat exchanger210A, since the communication hole224is provided in the region in which an increase in the pressure by boiling of the heat transfer medium C is more likely to occur, the pressure can be distributed with good responsiveness so that the pressure in the channel on the high-pressure side is shared with the channel on the low-pressure side through the communication hole224.

Other than this, the present embodiment has the same functions and effects as in the eighth embodiment.

Tenth Embodiment

As shown inFIG.33, a heat exchanger210B of a tenth embodiment differs from the heat exchanger210of the eighth embodiment in the position of the communication holes224provided in the partition member223of the second channel pipe220B. Although not shown in particular, in the heat exchanger210B, the first channel pipe220A and the third channel pipe220C also have the same structure as the second channel pipe220B.

The communication hole224is provided at both the joining portion223aof the partition member223joined to the convex portion225aof the internal fin225and the convex portion226aof the internal fin226, and the non-joining portion223bof the partition member223.

The rest of the configuration is the same as in the eighth embodiment.

In the heat exchanger210B, since the communication holes224are almost uniformly arranged in the partition member223, it is possible to improve the responsiveness for distributing the pressure so that the pressure in the channel on the high-pressure side is shared with the channel on the low-pressure side.

Other than this, the present embodiment has the same functions and effects as in the eighth embodiment.

Eleventh Embodiment

As shown inFIG.34, a heat exchanger210C of an eleventh embodiment differs from the heat exchanger210B of the tenth embodiment in the position of the communication holes224provided in the partition member223of the second channel pipe220B. Although not shown in particular, in the heat exchanger210C, the first channel pipe220A and the third channel pipe220C also have the same structure as the second channel pipe220B.

Unlike the case of the heat exchanger210B of the tenth embodiment, the communication holes224are provided only in the facing region T of the partition member223.

The rest of the configuration is the same as in the tenth embodiment.

In the heat exchanger210C, since the number of communication holes224is reduced, the cost required for processing the communication holes224can be reduced. Furthermore, since the communication holes224are retained in the facing region T in which an increase in the pressure by boiling of the heat transfer medium C is more likely to occur, it is possible to prevent deterioration of the responsiveness for distributing the pressure so that the pressure in the channel on the high-pressure side is shared with the channel on the low-pressure side.

Other than this, the present embodiment has the same functions and effects as in the tenth embodiment.

Twelfth Embodiment

As shown inFIG.35, a heat exchanger210D of a twelfth embodiment differs from the heat exchanger210C of the eleventh embodiment in the structure of communication holes224A provided in the partition member223of the second channel pipe220B. Although not shown in particular, in the heat exchanger210D, the first channel pipe220A and the third channel pipe220C also have the same structure as the second channel pipe220B.

The communication hole224A is configured as a screw hole having an inner peripheral surface with a screw thread, and differs from the communication hole224having a constant inner diameter in the lamination direction X. The inner peripheral surface of the communication hole224A has a larger surface area (heat transfer area) than the inner peripheral surface of the communication hole224.

The rest of the configuration is the same as in the eleventh embodiment.

In the heat exchanger210D, since the partition member223is provided with the communication holes224A having a larger heat transfer area than the communication holes224, the heat exchange performance can be improved.

Other than this, the present embodiment has the same functions and effects as in the eleventh embodiment.

A modification particularly related to the twelfth embodiment may have a structure in which the communication holes224of each of Embodiments 8 to 10 are replaced with the communication holes224A.

Thirteenth Embodiment

As shown inFIG.36, a heat exchanger210E of a thirteenth embodiment differs from the heat exchanger210C of the eleventh embodiment in the structure of communication holes224B provided in the partition member223of the second channel pipe220B. Although not shown in particular, in the heat exchanger210E, the first channel pipe220A and the third channel pipe220C also have the same structure as the second channel pipe220B.

The communication hole224B is configured to extend obliquely with respect to the lamination direction X, which is the thickness direction of the partition member223. The inner peripheral surface of the communication hole224B has a larger surface area (heat transfer area) than the inner peripheral surface of the communication hole224.

The rest of the configuration is the same as in the eleventh embodiment.

In the heat exchanger210E, since the partition member223is provided with the communication holes224B having a larger heat transfer area than the communication holes224, the heat exchange performance can be improved.

Other than this, the present embodiment has the same functions and effects as in the eleventh embodiment.

A modification particularly related to the thirteenth embodiment may have a structure in which the communication holes224of each of Embodiments 8 to 10 are replaced with the communication holes224B.

Fourteenth Embodiment

As shown inFIG.37, a heat exchanger210F of a fourteenth embodiment differs from the heat exchanger210E of the thirteenth embodiment in the structure of communication holes224C provided in the partition member223of the second channel pipe220B. Although not shown in particular, in the heat exchanger210F, the first channel pipe220A and the third channel pipe220C also have the same structure as the second channel pipe220B.

The communication hole224C is configured as a screw hole that extends obliquely with respect to the lamination direction X, which is the thickness direction of the partition member223, and has an inner peripheral surface with a screw thread. The inner peripheral surface of the communication hole224C has a larger surface area (heat transfer area) than the inner peripheral surface of the communication hole224B.

The rest of the configuration is the same as in the thirteenth embodiment.

In the heat exchanger210F, since the partition member223is provided with the communication holes224C having a larger heat transfer area than the communication holes224B, the heat exchange performance can be improved.

Other than this, the present embodiment has the same functions and effects as in the thirteenth embodiment.

A modification particularly related to the fourteenth embodiment may have a structure in which the communication holes224of each of Embodiments 8 to 10 are replaced with the communication holes224C.

Fifteenth Embodiment

As shown inFIG.38, a heat exchanger210G of a fifteenth embodiment differs from the heat exchanger210of the eighth embodiment in the structure of two internal fins225A and226A provided in the second channel pipe220B. Although not shown in particular, in the heat exchanger210G, the first channel pipe220A and the third channel pipe220C also have the same structure as the second channel pipe220B.

When the communication hole224of the partition member223is a first communication hole, the internal fin225A is provided with a second communication hole225cthrough which two adjacent narrow channels of the plurality of narrow channels228acommunicate with each other. Similarly, the internal fin226A is provided with a second communication hole226cthrough which two adjacent narrow channels of the plurality of narrow channels229acommunicate with each other.

The rest of the configuration is the same as in the eighth embodiment.

In the heat exchanger210G, in addition to the effect that the communication hole224prevents an imbalance in the pressure and the flow rate between the first channel228and the second channel229, the second communication hole225ccan prevent an imbalance in the pressure and the flow rate between the plurality of narrow channels228aof the first channel228, and the second communication hole226ccan prevent an imbalance in the pressure and the flow rate between the plurality of narrow channels229aof the second channel229.

Other than this, the present embodiment has the same functions and effects as in the eighth embodiment.

A modification particularly related to the fifteenth embodiment may have a structure in which the internal fins225and226of each of Embodiments 9 to 14 are replaced with the internal fins225A and226A.

Sixteenth Embodiment

As shown inFIG.39, a heat exchanger210H of a sixteenth embodiment differs from the heat exchanger210of the eighth embodiment in the structure of the second channel pipe220B. Although not shown in particular, in the heat exchanger210H, the first channel pipe220A and the third channel pipe220C also have the same structure as the second channel pipe220B.

In the second channel pipe220B, the internal fins225and226are not provided.

The rest of the configuration is the same as in the eighth embodiment.

The heat exchanger210H allows a more simplified structure than the heat exchanger210.

Other than this, the present embodiment has the same functions and effects as in the eighth embodiment.

A modification particularly related to the sixteenth embodiment may have a structure in which the internal fins225and226or the internal fins225A and226A of each of Embodiments 9 to 15 are omitted.

The present disclosure is not limited to only the typical embodiments described above, but may be subjected to various applications or changes without departing from the object of the present disclosure. For example, the following embodiments can be implemented by applying the above embodiments.

The above embodiments show an example in which the heat exchanger exchanges heat with the semiconductor module201as the heat exchange object. Instead, the heat exchange object may be an object other than the semiconductor module201.

The above embodiments show an example in which a structure including the partition member223provided with the communication hole224,224A,224B, or224C is applied to the heat exchanger using the cooling medium as the heat transfer medium C. Instead, this structure may be applied to a heat exchanger using a heating medium.

The above embodiments show an example in which the channel pipe is partitioned by the partition member223into two channels. Instead, the heat exchanger may have a structure in which the channel pipe is partitioned by the partition member223into three or more channels. In this case, the heat exchanger is configured such that at least two of the three or more channels communicate with each other through a region corresponding to the communication hole224,224A,224B, or224C.

Next, Embodiments 17 to 42 of the heat exchanger of the third aspect and the fourth aspect of the present disclosure will be described with reference to the drawings. An object of the disclosure is to provide a heat exchanger capable of ensuring a smooth flow of coolant to improve the cooling performance for an electronic component, thereby improving heat exchanger performance.

Seventeenth Embodiment

As shown inFIGS.40and41, a component cooling device301of the present embodiment includes a cooling pipe303, a first electronic component321, and a second electronic component322. The cooling pipe303is provided inside with a coolant channel330through which a coolant is circulated. The first electronic component321and the second electronic component322are arranged thermally in contact with a cooling surface331of the cooling pipe303. Arrows w shown inFIGS.40and41indicate the flows of coolant when no boiling occurs. The same applies to the subsequent figures.

The first electronic component321is arranged on an upstream side of the second electronic component322in the coolant channel330.

The coolant channel330has an intermediate region303M, an upstream region303U, and a downstream region303D that are defined as follows. The intermediate region303M is a region of the coolant channel330that is located on a downstream side of the first electronic component321and an upstream side of the second electronic component322. The upstream region303U is a region of the coolant channel330that is located between an upstream end of the first electronic component and a downstream end of the first electronic component. The downstream region303D is a region of the coolant channel330that is located between an upstream end of the second electronic component and a downstream end of the second electronic component.

In the intermediate region303M, a fluid diode unit332is provided. The fluid diode unit332causes a channel resistance in a direction from the downstream region303D toward the upstream region303U to be higher than a channel resistance in a direction from the upstream region303U toward the downstream region303D.

The channel resistance in the direction from the downstream region303D toward the upstream region303U indicates a channel resistance to a flow of coolant from the downstream region303D toward the upstream region303U. The channel resistance in the direction from the upstream region303U toward the downstream region303D indicates a channel resistance to a flow of coolant from the upstream region303U toward the downstream region303D.

The component cooling device301of the present embodiment has the cooling surface331on one of main surfaces of the cooling pipe303. The first electronic component321and the second electronic component322are arranged in contact with the cooling surface331. The cooling pipe303is provided inside with the coolant channel330so that the coolant flows in a longitudinal direction of the cooling pipe303.

A normal direction of the cooling surface331, that is, a lamination direction of the cooling pipe303and each of the first electronic component321and the second electronic component322is referred to as X direction as appropriate. A channel direction in which the coolant is circulated through the coolant channel330is referred to also as Y direction as appropriate. A direction orthogonal to both the X direction and the Y direction is referred to as Z direction as appropriate. The first electronic component321and the second electronic component322are arranged side by side in the Y direction.

In the present embodiment, the fluid diode unit332is composed of a pair of protruding pieces332athat protrude inward from respective inner wall surfaces of the coolant channel330at both ends in the X direction. The protruding piece332amay be a plate-shaped member that is inclined so that a part of the plate-shaped member closer to the inner side of the coolant channel330in the Z direction is located closer to the downstream side. Thus, the fluid diode unit332has the function described above.

The fluid diode unit332is not particularly limited as long as the fluid diode unit332has the predetermined function described above, and may be composed of, for example, a single protruding piece332a. The fluid diode unit332may be integrally formed with the cooling pipe303, or may be joined to the cooling pipe303.

The first electronic component321and the second electronic component322may be, for example, a power semiconductor device. The first electronic component321and the second electronic component322may be, for example, a power semiconductor device constituting a switching circuit unit of a power conversion device. The power conversion device may be, for example, a power conversion device configured to be mounted on the vehicle and perform power conversion between DC power and AC power.

The coolant circulated through the coolant channel330is, for example, a liquid coolant such as water. However, in some cases, a part of the liquid coolant may boil and be vaporized.

Next, functions and effects of the present embodiment will be described.

In the component cooling device301, the fluid diode unit332is provided in the intermediate region303M. Thus, even when a part of the liquid coolant in the downstream region303D is evaporated to be vapor by heat of the second electronic component322on the downstream side, the vapor can be prevented from flowing backward to the upstream region303U. As a result, the vapor is easily discharged from a downstream end of the coolant channel330at an early timing, leading to smooth introduction and circulation of the liquid coolant in the coolant channel.

Therefore, a smooth flow of liquid coolant from the upstream side toward the downstream side of the coolant channel330can be ensured. As a result, the cooling performance for the first electronic component321and the second electronic component322can be improved.

As described above, the present embodiment can provide a component cooling device capable of ensuring a smooth flow of coolant to improve the cooling performance for an electronic component.

Eighteenth Embodiment

As shown inFIGS.42to46, the present embodiment is an embodiment in which the component cooling device301includes the plurality of cooling pipes303laminated together with the first electronic component321and the second electronic component322.

Specifically, the plurality of cooling pipes303are arranged substantially parallel to each other in the X direction, and the first electronic component321and the second electronic component322are arranged between adjacent cooling pipes303. Accordingly, the first electronic component321and the second electronic component322are sandwiched between two cooling pipes303adjacent to each other in the X direction. Thus, the first electronic component321and the second electronic component322are cooled from both sides.

Each of the first electronic component321and the second electronic component322is molded with resin and constitutes a component module320. Both main surfaces of the component module320are radiation surfaces thermally connected to the first electronic component321or the second electronic component322. The component module320is arranged so that the radiation surfaces are thermally in contact with the cooling pipe303.

The cooling pipes303are connected to each other via a connecting pipe313in the vicinity of both end portions in the Y direction so that a first cooling pipe303is connected to a second cooling pipe303adjacent to the first cooling pipe303in the X direction. The cooling pipe303arranged at one end in the X direction is provided with an introduction port311from which the coolant is introduced and a discharge port312from which the coolant is discharged. As shown inFIG.44, at a portion of each of the cooling pipes303connected to the connecting pipe313, the cooling pipe303has an introduction portion303afrom which the coolant is introduced and a discharge portion303bfrom which the coolant is discharged.

As shown inFIGS.43and44, each of the cooling pipes303is provided inside with an internal fin304. The internal fin304is composed of a member separate from outer shell plates333constituting an outer shell of the cooling pipe303. Specifically, as shown inFIG.43, the cooling pipe303is composed of the pair of outer shell plates333, and the internal fin304arranged in an internal space formed between the pair of outer shell plates333.

The pair of outer shell plates333are joined to each other at end edges. The internal fin304has a fin body340that is formed to extend in the Y direction. As shown inFIG.43, a cross section of the fin body340orthogonal to the Y direction has a continuous concave and convex shape. The convex portions of the fin body340are in contact with an inner surface of the outer shell plate333. The internal fin304is joined to the outer shell plate333at the convex portions.

In the present embodiment, as shown inFIGS.44and45, the fluid diode unit332is formed as a part of the internal fin304. Specifically, the fluid diode unit332is composed of an inclined fin341and a connection fin342. The inclined fin341has a portion inclined with respect to the channel direction (i.e., Y direction) of the coolant channel330. The connection fin342is connected to the inclined fin341on an upstream side of a downstream end portion341aof the inclined fin341. The connection fin342is formed to extend from the portion connected to the inclined fin341toward a downstream side. A part of the fin body340constitutes the connection fin342.

As shown inFIG.44, the fin body340is separately arranged at an upstream side portion and a downstream side portion in the Y direction of the coolant channel330. A downstream end of the fin body340on the upstream side and an upstream end of the fin body340on the downstream side are arranged in a part of the intermediate region303M. The inclined fin341is arranged at the upstream end of the fin body340on the downstream side. As shown inFIG.45, a part of the upstream end of the fin body340connected to the inclined fin341serves as the connection fin342. That is, it can also be said that the fluid diode unit332is formed of a part of the fin body340on the downstream side and the inclined fin341connected to the part of the fin body340on the downstream side.

As shown inFIG.45, when viewed from the X direction, the inclined fin341is formed in a linear shape and inclined with respect to the Y direction. The connection fin342is formed in a linear shape extending in the Y direction. When viewed from the X direction, an acute-angled space301awhich is a space having an acute angle and an obtuse-angled space302awhich is a space having an obtuse angle are present between the inclined fin341and the connection fin342.

The acute-angled space301and the obtuse-angled space302aare both a space facing the downstream side of the inclined fin341. The coolant flowing from the downstream region303D toward the upstream region303U is partially blocked by the acute-angled space301a. In particular, the coolant evaporated to be gas bubbles tends to enter the acute-angled space301and be prevented from flowing toward the upstream side of the acute-angled space301a. Thus, the fluid diode unit332that increases the channel resistance in the direction from the downstream region303D toward the upstream region303U is formed in the intermediate region303M.

The fluid diode unit332is formed in the vicinity of a center portion in the Z direction of the coolant channel330and is not formed at an outer portion in the Z direction of the coolant channel330. The plurality of inclined fins341are formed so that the inclined fins341located above the center portion in the Z direction of the coolant channel330and the inclined fins341located below the center portion are inclined in opposite directions. Thus, the inclined fin341is inclined so that a part of the inclined fin341closer to the downstream side in the Y direction is located closer to the center in the Z direction of the coolant channel330.

In other words, as shown inFIG.45, the fluid diode unit332has a guide surface332bthat guides the coolant from outside to inside in a width direction (i.e., Z direction) orthogonal to both the channel direction (i.e., Y direction) of the coolant channel330and the normal direction (i.e., X direction) of the cooling surface331. The guide surface332bis a surface on the upstream side of main surfaces of the inclined fin341.

As shown inFIG.44, a diffusion unit305through which adjacent branch channels337communicate with each other is provided between the internal fin304on the upstream side and the internal fin304on the downstream side. The diffusion unit305is provided only in the intermediate region303M among the upstream region303U, the intermediate region303M, and the downstream region303D.

The rest of the configuration is the same as in the seventeenth embodiment. Of reference numerals used in the eighteenth embodiment and subsequent embodiments, the same reference numerals as those used in the previously described embodiment indicate the same components or the like as in the previously described embodiment unless otherwise specified.

In the present embodiment, the fluid diode unit332is formed of the inclined fin341and the connection fin342. Thus, the fluid diode unit332has the acute-angled space301afacing the downstream side. Therefore, the channel resistance in the direction from the downstream region303D toward the upstream region303U can be effectively increased. As a result, the vapor of the coolant is prevented from flowing backward to the upstream region303U, leading to smooth circulation of the liquid coolant.

The fluid diode unit332has the guide surface332b. Thus, as shown inFIG.46, the guide surface332bguides the coolant toward the center side in the Z direction, and a flow rate of the coolant at the center portion in the Z direction can be increased. Due to the increase in the flow rate, the gas bubbles captured in the acute-angled space301aare more likely to be guided toward the downstream side. As a result, dry-out in the downstream region303D can be prevented, thereby improving the cooling performance for the second electronic component322.

Since the diffusion unit305is formed in the intermediate region303M, the cooling performance can be effectively improved by an advantageous effect same as an advantageous effect described in detail in the thirty-third embodiment described later.

Other than this, the present embodiment has the same functions and effects as in the seventeenth embodiment.

First Comparative Embodiment

As shown inFIG.47, this comparative embodiment is an embodiment in which a component cooling device includes a cooling pipe309not including any fluid diode unit. More specifically, the comparative embodiment is an embodiment obtained by removing the inclined fins341from the cooling pipe303shown in the eighteenth embodiment. The internal fin304is continuously formed to extend in the Y direction from the upstream side of the upstream region303U to the downstream side of the downstream region303D.

The rest of the configuration is the same as in the eighteenth embodiment.

In some cases, part of the vapor of the coolant evaporated in the downstream region flows through the intermediate region303M toward the upstream region303U. In this case, if no fluid diode unit is formed in the intermediate region303M, the vapor of the coolant flows backward as indicated by arrow wr and reaches the upstream region303U. In that case, the vapor of the coolant is less likely to be smoothly discharged from the discharge unit303b.

In this regard, as shown inFIG.46, in the component cooling device301of the eighteenth embodiment, the fluid diode unit332can prevent the vapor of the coolant from flowing to the upstream region303U. Thus, the vapor is discharged from the discharge unit303bto achieve a smooth flow of liquid coolant.

Nineteenth Embodiment

As shown inFIGS.48and49, the present embodiment is an embodiment in which the component cooling device301is provided with the fluid diode unit332formed at a part of a wave fin304W as the internal fin304.

In the present embodiment, as shown inFIG.48, the wave fin304W is arranged in the coolant channel330. The wave fin304W has a corrugated shape whose inclination direction with respect to the channel direction (i.e., Y direction) is alternately changed when viewed from the normal direction (i.e., X direction) of the cooling surface331. The fluid diode unit332is formed at a part of the wave fin304W.

Specifically, as shown inFIG.49, the fluid diode unit332is formed at a part of a portion of the wave fin304W at which the inclination direction with respect to the Y direction is reversed. Thus, the fluid diode unit332is formed by deforming a part of the wave fin304W.

The part of the wave fin304W at which the fluid diode unit332is formed is also the inclined fin341that is inclined with respect to the Y direction. The fluid diode unit332is formed of a protruding downstream end of the inclined fin341. Also in the present embodiment, as shown inFIG.48, the fluid diode unit332is formed at a part in the Z direction of the coolant channel330. Specifically, the fluid diode unit332is formed in the vicinity of the center portion in the Z direction and is not formed at the outer portion in the Z direction.

In the present embodiment, the cooling pipe303is arranged so that the width direction orthogonal to both the channel direction of the coolant channel330and the normal direction of the cooling surface331is a vertical direction (i.e., direction of gravity). That is, the cooling pipe303is arranged so that the Z direction is the vertical direction. The coolant channel330has a vertical communication portion335in the intermediate region303M. The vertical communication portion335communicates in the vertical direction from below a center of the first electronic component321to above an upper end of the second electronic component322.

The width direction (i.e., Z direction) of the coolant channel330may be slightly inclined with respect to the vertical direction. The vertical communication portion335also does not necessarily need to be parallel to the vertical direction, and is allowed to be slightly inclined with respect to the vertical direction as long as the vertical communication portion335has a function described later.

In the present embodiment, the vertical communication portion335is formed by cutting off a part of the internal fin304. Specifically, in the present embodiment, the wave fin304W which is the internal fin304is continuously formed in a region including the upstream region303U, the intermediate region303M, and the downstream region303D. A part of the wave fin304W is broken by a plurality of communication spaces351and a plurality of communication spaces352communicating with each other in the vertical direction provided in the intermediate region303M.

The vertical communication portion335has two communication spaces351formed on a lower side in the vertical direction and two communication spaces352formed on an upper side in the vertical direction. The communication spaces351and the communication spaces352are formed to be deviated from each other in the Y direction. However, the communication spaces351and the communication spaces352are connected to each other through the channel along the wave fin304W. As a result, the lower communication spaces351and the upper communication spaces352communicate with each other.

A lower end of the lower communication space351is arranged at least below the center of the first electronic component321, and an upper end of the upper communication space352is arranged at least above the upper end of the second electronic component322. Thus, the vertical communication portion335composed of the communication spaces351,352communicates in the vertical direction from below the center of the first electronic component321to above the upper end of the second electronic component322.

The fluid diode unit332is formed on the downstream side of the vertical communication portion335.

In particular, in the present embodiment, the inclined fin341is formed adjacent to a downstream end of the vertical communication portion335. The fluid diode unit332is formed in the vicinity of the downstream end of the inclined fin341. A main surface on the upstream side of the inclined fin341is the guide surface332b.

In the present embodiment, the vertical communication portion335also functions as the diffusion unit305. Specifically, in the component cooling device301of the present embodiment, only in the intermediate region303M among the upstream region303U, the intermediate region303M, and the downstream region303D, the internal fin304is provided with the diffusion unit305through which adjacent branch channels337communicate with each other.

The rest of the configuration is the same as in the seventeenth embodiment.

In the present embodiment, since the internal fin304has the wave fin304W, the heat transfer area with the coolant can be increased, thereby improving the cooling performance. The fluid diode unit332is formed at a part of the wave fin304W. Thus, the fluid diode unit332can be provided by using the corrugated shape of the wave fin304W and deforming a part of the wave fin304W. Therefore, the fluid diode unit332can be easily formed at low cost.

The vertical communication portion335allows the evaporated coolant to move above the second electronic component322. Specifically, for example, when the coolant heated by the first electronic component321is evaporated to be gas bubbles and the gas bubbles reach the intermediate region303M, the gas bubbles move upward through the vertical communication portion335. Accordingly, even when the gas bubbles flow to the downstream region303D, the gas bubbles pass through the upper side of the second electronic component322. Thus, deterioration of the coolability for the second electronic component322due to the gas bubbles can be prevented.

The fluid diode unit332is formed on the downstream side of the vertical communication portion335. Thus, some of the gas bubbles leaking from the fluid diode unit332toward the upstream side of the fluid diode unit332can move above the second electronic component322through the vertical communication portion335.

The vertical communication portion335also functions as the diffusion unit305. Thus, the cooling performance can be effectively improved by an advantageous effect that is the same as the advantageous effect described in detail in the thirty-third embodiment described later.

Other than this, the present embodiment has the same functions and effects as in the eighteenth embodiment.

Next,FIGS.50and51show the results of an effect confirmation test using the component cooling device301of the nineteenth embodiment. Specifically, a heat transfer coefficient from the second electronic component322to the coolant has been analyzed both in a non-boiling state and in a boiling state of the coolant. As comparison, the heat transfer coefficient has also been analyzed in a component cooling device390(i.e., comparative sample) including a cooling pipe393provided with no fluid diode unit or no diffusion unit (i.e., vertical communication portion) as shown inFIG.52.

In the analysis of the heat transfer coefficient, a flow rate of the coolant at a position facing the second electronic component322has been calculated by simulation. Then, the heat transfer coefficient has been calculated from a relationship between the flow rate of the coolant and the heat transfer coefficient acquired in advance by using an actual device.

FIG.50shows the heat transfer coefficient from the second electronic component322to the coolant in the non-boiling state.FIG.51shows the heat transfer coefficient from the second electronic component322to the coolant in the boiling state.FIGS.50and51show side by side the results of both the comparative sample and the sample of the nineteenth embodiment.

As shown inFIGS.50and51, in both the non-boiling state and the boiling state, the use of the component cooling device301of the nineteenth embodiment increases the heat transfer coefficient of the second electronic component322. In particular, in the boiling state, as shown inFIG.51, the heat transfer coefficient of the component cooling device301of the nineteenth embodiment is higher by approximately 50 percent than the heat transfer coefficient of the comparative sample.

The above results have been obtained presumably because in the non-boiling state, particularly due to the guide surface332b, the liquid coolant flowing toward the downstream region303D is easily collected in the vicinity of the center in the Z direction of the coolant channel330, leading to the increase in the flow rate of the coolant that exchanges heat with the second electronic component322.

The above results have been obtained presumably because in the boiling region, due to the fluid diode unit332, the coolant is prevented from flowing backward from the downstream region303D to the upstream region303U, leading to the increase in the amount of coolant introduced in the vicinity of the center in the Z direction of the downstream region303D.

Twentieth Embodiment

As shown inFIG.53, the present embodiment is an embodiment obtained by changing the arrangement of the vertical communication portion335of the nineteenth embodiment.

Specifically, one of the upper communication spaces352is arranged on the downstream side in the Y direction of the lower communication spaces351.

The fluid diode unit332located on the downstream side of the upper communication space352is arranged at a position on the downstream side in the Y direction of the fluid diode unit332located on the downstream side of the lower communication space351.

Other than this, the present embodiment has the same configuration and functions and effects as in the nineteenth embodiment.

As shown inFIG.54, the present embodiment is an embodiment obtained by changing the positional relationship between the vertical communication portion335and the fluid diode unit332of the nineteenth embodiment.

Specifically, the fluid diode unit332on the lower side is arranged between the two lower communication spaces351.

Other than this, the present embodiment has the same configuration and functions and effects as in the nineteenth embodiment.

As shown inFIG.55, the present embodiment is an embodiment in which the vertical communication portion335is formed of a single lower communication space351and a single upper communication space352. In the present embodiment, the lower communication space351is arranged on the upstream side in the Y direction of the upper communication space352. The fluid diode unit332on the lower side is arranged on the upstream side of the fluid diode unit332on the upper side.

The rest of the configuration is the same as in the nineteenth embodiment.

In the present embodiment, the heat transfer area of the internal fin304is larger than in the nineteenth embodiment.

Other than this, the present embodiment has the same functions and effects as in the nineteenth embodiment.

As shown inFIG.56, the present embodiment is also an embodiment in which the vertical communication portion335is formed of a single lower communication space351and a single upper communication space352. In the present embodiment, the lower communication space351is arranged on the downstream side in the Y direction of the upper communication space352. The fluid diode unit332on the lower side is arranged on the downstream side of the fluid diode unit332on the upper side.

Other than this, the present embodiment has the same configuration and functions and effects as in the nineteenth embodiment.

As shown inFIG.57, the present embodiment is an embodiment in which the vertical communication portion335is composed of six communication spaces353located at different positions in the Z direction.

The six communication spaces353are arranged so that the communication space353closer to the center portion in the Z direction is located closer to the downstream side in the Y direction. The fluid diode unit332is formed on the downstream side of each of the two communication spaces353arranged in the vicinity of the center in the Z direction.

Other than this, the present embodiment has the same configuration and functions and effects as in the nineteenth embodiment.

In the present embodiment, the number of communication spaces353is not particularly limited as long as the number of communication spaces353is three or more.

As shown inFIG.58, the present embodiment is an embodiment in which the lower communication space351has a larger width in the Y direction than the upper communication space352.

The upper communication space352is directly connected to the lower communication space351. Furthermore, a center in the Y direction of the upper communication space352is located at substantially the same position as a center in the Y direction of the lower communication space351.

Other than this, the present embodiment has the same configuration and functions and effects as in the nineteenth embodiment.

As shown inFIG.59, the present embodiment is an embodiment in which the upper communication space352has a larger width in the Y direction than the lower communication space352.

The upper communication space352is directly connected to the lower communication space351. Furthermore, an upstream end in the Y direction of the upper communication space352is located at substantially the same position as an upstream end in the Y direction of the lower communication space351.

Other than this, the present embodiment has the same configuration and functions and effects as in a twenty-fifth embodiment.

As shown inFIG.60, the present embodiment is an embodiment in which the vertical communication portion335is formed of a single communication space.

Specifically, the vertical communication portion335composed of the single communication space is linearly formed in the Z direction from below the center of the first electronic component321to above the upper end of the second electronic component322. In particular, in the present embodiment, a lower end of the vertical communication portion335is arranged at a position of a lower end in the Z direction of the second electronic component322.

The rest of the configuration is the same as in the nineteenth embodiment.

In the present embodiment, the vertical communication portion335can be simplified. Furthermore, the region from which the internal fin304is removed can be reduced. Thus, the gas bubbles can be easily released upward while the heat transfer area with the coolant is maintained to be large.

Other than this, the present embodiment has the same functions and effects as in the nineteenth embodiment.

As shown inFIG.61, the present embodiment is an embodiment in which two upper communication spaces352and a single lower communication space351are provided.

With respect to the two communication spaces352arranged in the Y direction, the fluid diode unit332on the upper side is formed on the downstream side of the communication space352on the downstream side.

Other than this, the present embodiment has the same configuration and functions and effects as in the nineteenth embodiment.

As shown inFIG.62, the present embodiment is an embodiment in which narrowed portions336are arranged at both end portions in the Z direction of the intermediate region303M of the coolant channel330.

Specifically, the pair of narrowed portions336protrude from both ends toward the center in the Z direction of the coolant channel330. Between the pair of narrowed portions336, a narrowed opening360through which the coolant channels330communicate with each other in the Y direction is formed. The narrowed opening360is formed at a position in the Z direction corresponding to the first electronic component321and the second electronic component322.

The internal fin304is separately provided on the upstream side of the narrowed portions336and on the downstream side of the narrowed portions336. The fluid diode unit332is formed at an upstream end of the internal fin304on the downstream side. The fluid diode unit332is formed in the range in the Z direction in which the narrowed opening360is formed.

The fluid diode unit332has the inclined fin341. However, the inclined fin341of the component cooling device301of the present embodiment has a shorter length than the inclined fin341shown in the eighteenth embodiment (seeFIGS.44and45). In the present embodiment, an upstream end of the inclined fin341is connected to an upstream end of the fin body340.

A space between the internal fin304on the upstream side and the internal fin304on the downstream side constitutes the diffusion unit305through which adjacent branch channels337communicate with each other.

The rest of the configuration is the same as in the eighteenth embodiment.

In the present embodiment, as shown inFIG.63, a flow of coolant in the downstream region303D can be concentrated in the vicinity of the center in the Z direction. Thus, it is possible to increase the flow rate of the coolant in the vicinity of the center in the Z direction in the downstream region303D. Accordingly, the cooling performance for the second electronic component322can be improved.

Since the diffusion unit305is formed in the intermediate region303M, the cooling performance can be effectively improved by an advantageous effect same as the advantageous effect described in detail in the thirty-third embodiment described later.

Other than this, the present embodiment has the same functions and effects as in the eighteenth embodiment.

Thirtieth Embodiment

As shown inFIGS.64and65, the present embodiment is an embodiment obtained by changing the shape of the fluid diode unit332of a twenty-ninth embodiment.

Specifically, in the present embodiment, the fluid diode unit332includes the inclined fins341on both sides in the Z direction of the upstream end of the fin body340of the internal fin304. Thus, the acute-angled spaces301aare provided on the both sides of the fin body340.

The rest of the configuration is the same as in the seventeenth embodiment.

In the present embodiment, it is possible to increase the channel resistance in the direction from the downstream region303D toward the upstream region303U in the fluid diode unit332. Thus, the evaporated coolant can be more effectively prevented from flowing backward from the downstream region303D to the upstream region303U.

Other than this, the present embodiment has the same functions and effects as in the seventeenth embodiment.

As shown inFIG.66, the present embodiment is an embodiment obtained by changing the shape of the narrowed portions336of a thirtieth embodiment. In the present embodiment, an inclined end surface361is provided at a protruding end in the Z direction of the narrowed portion336. The inclined end surface361is inclined so that a part of the inclined end surface361closer to the downstream side in the Y direction is located closer to the center side in the Z direction.

The rest of the configuration is the same as in a thirtieth embodiment.

In the present embodiment, since the narrowed portions336have the inclined end surface361, it is possible to achieve a smooth flow of coolant passing through the narrowed opening360toward the downstream side. Also the narrowed portions336allow the channel resistance in the direction from the downstream region303D toward the upstream region303U to be higher than the channel resistance in the direction from the upstream region303U toward the downstream region303D. Thus, the narrowed portions336can also function as the fluid diode unit332.

Other than this, the present embodiment has the same functions and effects as in a thirtieth embodiment.

As shown inFIGS.67and68, the present embodiment is an embodiment obtained by changing the shape of the internal fin304of a twenty-fifth embodiment.

In the present embodiment, as in a twenty-fifth embodiment, the vertical communication portion335is provided in the intermediate region303M. The vertical communication portion335connects the lower communication space351to the upper communication space352in the Z direction. A downstream end of the lower communication space351is aligned with a downstream end of the upper communication space352.

The fluid diode unit332is formed on the downstream side of the vertical communication portion335. As shown inFIG.68, the fluid diode unit332is composed of the inclined fin341and the connection fin342. The connection fin342is inclined in the same direction as the inclined fin341with respect to the Y direction. However, an inclination angle of the connection fin342with respect to the Y direction is smaller than an inclination angle of the inclined fin341with respect to the Y direction. Thus, the acute-angled space301ais formed between the inclined fin341and the connection fin342.

A downstream end of the connection fin342has a downstream end fin342athat is inclined in a direction opposite to the inclination direction of the connection fin342. An upstream end of the inclined fin341has an upstream end fin341bthat is formed to extend in the Y direction.

Over the entire internal fin304, a communication unit370through which the branch channels337communicate with each other is formed.

The rest of the configuration is the same as in a twenty-fifth embodiment.

In the present embodiment, the coolant is prevented from flowing backward and the coolant is easily distributed in the Z direction. Therefore, the coolability for the first electronic component321and the second electronic component322can be further improved easily.

Other than this, the present embodiment has the same functions and effects as in a twenty-fifth embodiment.

As shown inFIGS.69to70, the present embodiment is an embodiment in which a component cooling device310as a heat exchanger is provided with the diffusion unit305described below at a specific part of the internal fin304.

The cooling pipe303includes the internal fin304that partitions the coolant channel330into the plurality of branch channels337that extend parallel to each other in the channel direction Y.

As shown inFIG.69, only in the intermediate region303M among the upstream region303U, the intermediate region303M, and the downstream region303D, the internal fin304is provided with the diffusion unit305through which adjacent branch channels communicate with each other.

The plurality of branch channels337that extend parallel to each other in the channel direction Y indicate the plurality of branch channels337formed in parallel to each other to extend in the channel direction Y as a whole, and the plurality of branch channels337may have a portion inclined with respect to the channel direction Y.

As shown inFIGS.70and71, the internal fin304is made of a metal plate bent in a thickness direction, and has concave and convex portions in the X direction. In the present embodiment, as shown inFIG.69, the internal fin304formed by bending a single metal plate is arranged in a region including the upstream region303U, the intermediate region303M, and the downstream region303D.

The internal fin304has the corrugated wave fin304W whose inclination direction with respect to the channel direction Y is alternately changed when viewed from the normal direction X of the cooling surface331. The diffusion unit305is formed at a part of the wave fin304W.

Thus, the wave fin304W is formed at a part of the internal fin304. The diffusion unit305is formed at a part of the wave fin304W. In the present embodiment, the wave fin304W is formed in the entire area of the upstream region303U, the intermediate region303M, and the downstream region303D. On the upstream side and the downstream side of the wave fins304W, straight fins304S that are parallel to the Y direction are formed.

As shown inFIG.70, the diffusion unit305has a projection306which is a part of the internal fin304projecting toward one of the branch channels337.

In the present embodiment, a cut is made at a part of the metal plate constituting the internal fin304, and the part of the metal plate is subjected to bending. Thus, at a part of the internal fin304, the projection306is formed and an opening307is also formed.

More specifically, as shown inFIGS.70and71, the internal fin304has a bottom wall portion401that is parallel to the Z direction and a side wall portion402that is erected in the Z direction. The bottom wall portion401and the side wall portion402are alternately continued in the Z direction to integrally form the internal fin304. The side wall portion402is bent in a plate thickness direction to form the corrugated wave fin304W. The branch channel337is formed between the side wall portions402adjacent to each other in the Z direction.

As shown inFIG.70, the projection306of the diffusion unit305is formed at a part of the side wall portion402. Specifically, the projection306is formed to project from a part of the side wall portion402toward one of the branch channels337. One side of the projection306closer to the bottom wall portion401is connected to the side wall portion402or the bottom wall portion401, and the other side of the projection306is cut off.

The opening307is formed at the part of the side wall portion402at which the projection306is formed. Thus, the opening307is formed adjacent to each of an upstream side and a downstream side of the projection306.

The side wall portion402of the wave fin304W is formed in a corrugated shape so that the inclination direction with respect to the Y direction is alternately changed. When portions of the side wall portion402at which the inclination direction with respect to the Y direction is reversed are assumed to be peaks and valleys, the diffusion unit305(i.e., the projection306and the opening307) is formed at a part of a unit side wall portion402a, which is a part of the side wall portion402between the peak and the valley adjacent to each other in the Y direction.

As shown inFIG.69, the diffusion unit305is not formed in the upstream region303U or the downstream region303D. The diffusion unit305in the intermediate region303M is formed substantially throughout the coolant channel330in the Z direction.

Unlike the component cooling devices301of Embodiments 17 to 32, the component cooling device310of the present embodiment includes no fluid diode unit. However, in the present embodiment, the fluid diode unit may be provided as appropriate.

The rest of the configuration is the same as in the eighteenth embodiment.

In the present embodiment, the diffusion unit305is formed in the intermediate region303M. Accordingly, as shown inFIGS.72and73, even when the coolant is evaporated to be vapor by heat of the first electronic component321and the second electronic component322, the vapor s can be diffused toward both sides in the Z direction through the diffusion unit305. Thus, the vapor s generated in the branch channel337in the vicinity of the center in the Z direction can be released toward both sides in the Z direction. Accordingly, in the vicinity of the center in the Z direction, the liquid coolant can be smoothly introduced and efficient cooling of the first electronic component321and the second electronic component322can be ensured.

Specifically, if the internal fin304is provided with no diffusion unit as shown inFIGS.74and75, the vapor s generated in the branch channel337in the vicinity of the center in the Z direction is spread in the Y direction. At this time, if an expansion pressure of the vapor s is larger than a supply pressure of the introduced liquid coolant, part of the vapor s flows backward from the downstream region303D toward the upstream region303U. In that case, in the branch channel337in the vicinity of the center in the Z direction, the vapor s is less likely to flow toward the discharge unit303b. Thus, the vapor s is retained in the coolant channel330and may cause a dry-out state. This may be a factor that deteriorates the cooling performance for the first electronic component321and the second electronic component322.

In this regard, since the component cooling device310shown in the thirty-third embodiment includes the diffusion unit305, as described above, the vapor s can be released toward both sides in the Z direction (seeFIG.72). Accordingly, in the vicinity of the center in the Z direction, the liquid coolant can be smoothly introduced and efficient cooling of the first electronic component321and the second electronic component322can be ensured.

The internal fin304is provided with the diffusion unit305only in the intermediate region303M among the upstream region303U, the intermediate region303M, and the downstream region303D. Therefore, the heat transfer area between the coolant and the internal fin304is easily ensured in the vicinity of the first electronic component321and the second electronic component322.

Since the diffusion unit305is provided only in the intermediate region303M, the pressure loss of the coolant can be reduced in the vicinity of the first electronic component321and the second electronic component322. Therefore, in the non-boiling state, the flow rate of the coolant that exchanges heat with the first electronic component321and the second electronic component322is easily ensured.

As described above, even when provision of the diffusion unit305causes a reduction in the heat transfer area or an increase in the pressure loss, the influence on cooling of the electronic component is small. Therefore, the diffusion unit305can be upsized, and distribution of the coolant in the boiling state as described above can be more smoothly performed.

The internal fin304has the wave fin304W, and the diffusion unit305is formed at a part of the wave fin304W. Thus, the heat transfer area between the internal fin304and the coolant can be effectively increased, thereby improving the cooling performance. Since the wave fin304W is provided with the diffusion unit305, the coolant can be more effectively diffused in the Z direction.

The diffusion unit305has the projection306. Thus, the heat transfer area between the internal fin304and the coolant can be further increased. Therefore, the cooling performance for the electronic component can be further improved.

As described above, also the present embodiment can provide a component cooling device capable of ensuring a smooth flow of coolant to improve the cooling performance for an electronic component.

Next,FIG.76shows the results of an effect confirmation test using the component cooling device310of the thirty-third embodiment. Specifically, a relationship between a heat transfer coefficient from the second electronic component322to the coolant and a superheating degree ΔT has been analyzed both in the non-boiling state and in the boiling state of the coolant. As comparison, the heat transfer coefficient has also been analyzed in a component cooling device (i.e., comparative sample) including a cooling pipe provided with no diffusion unit as shown inFIG.74.

The heat transfer coefficient has been analyzed by the same method as in the effect confirmation test in the nineteenth embodiment. The superheating degree ΔT is a difference between a temperature of the heat transfer surface and a saturation temperature of the coolant.

As shown inFIG.76, while the superheating degree ΔT is low and the coolant is in the non-boiling state, there is no particular difference in the heat transfer coefficient between the comparative sample and the sample of the thirty-third embodiment. When the superheating degree ΔT is increased and the coolant is in the boiling state, due to a boiling cooling effect, the heat transfer coefficient is increased, and up to a breaking point, as the superheating degree ΔT is increased, the heat transfer coefficient is also increased. However, in the comparative sample, the superheating degree ΔT reaches the breaking point earlier, and when the superheating degree ΔT exceeds the breaking point, a dry-out state (i.e., a state in which the coolant is vaporized on the entire heat transfer surface) occurs, and the heat transfer coefficient is suddenly reduced.

On the other hand, in the component cooling device310of the thirty-third embodiment, even when the superheating degree ΔT becomes high, the heat transfer coefficient is continuously increased. Therefore, even when the temperature of the second electronic component322is increased, the dry-out state is less likely to occur and a high heat transfer coefficient is achieved. Thus, the superheating degree ΔT before occurrence of the dry-out state is higher by approximately 20% than in the comparative sample.

The difference in the effect has been observed presumably because the diffusion unit305is provided in the intermediate region303M as shown inFIG.69. Specifically, the difference in the effect has been observed presumably because when the coolant is in the boiling state, as described above, it is possible to release the vapor s outward in the Z direction and ensure the flow rate of the coolant in the vicinity of the second electronic component322on the downstream side.

As shown inFIG.77, the present embodiment is an embodiment in which the projection306is upsized.

Specifically, the projection306is formed in the entire region from one end to a center portion of the unit side wall portion402a. Accordingly, the opening307is also formed in the entire region from one end to the center portion of the unit side wall portion402a.

An end edge on the downstream side of the projection306is continuous to the side wall portion402, and the opening307is formed on an upstream end side of the projection306.

The rest of the configuration is the same as in the thirty-third embodiment.

In the present embodiment, it is possible to increase a surface area of the projection306with which the coolant is relatively more likely to collide. Therefore, the heat transfer area between the coolant and the internal fin304can be increased.

Furthermore, the configuration of the diffusion unit305can be simplified, thereby enabling the internal fin304to be easy to manufacture. As a result, the component cooling device310that allows good productivity can be obtained.

Other than this, the present embodiment has the same functions and effects as in the thirty-third embodiment.

As shown inFIG.78, the present embodiment is an embodiment in which a part of the projection306is bent and extended toward the branch channel337to form an extending portion306a.

Specifically, a part of the projection306that projects to be inclined with respect to the side wall portion402is extended in a direction along the bottom wall portion401to form the extending portion306a.

The rest of the configuration is the same as in the thirty-fourth embodiment.

In the present embodiment, the heat transfer area with the coolant at the projection306can be increased by the area obtained by providing the extending portion306a.

Other than this, the present embodiment has the same functions and effects as in the thirty-fourth embodiment.

In the thirty-fifth embodiment, as in the thirty-fourth embodiment, the projection306is formed in the entire region from one end to the center portion of the unit side wall portion402a. However, as a modification of the thirty-fifth embodiment, as shown inFIG.79, the projection306may be configured such that while the projection306is formed at a part of the center portion of the unit side wall portion402aas in the thirty-third embodiment, the projection306is provided with the extending portion306a.

As shown inFIG.80, the present embodiment is an embodiment in which the projection306is curved in the plate thickness direction.

Specifically, the projection306has a curved surface portion that is convex toward the opening307.

Furthermore, there is a difference in level between the bottom wall portion401on a side opposite to a portion of the side wall portion402connected to the projection306and one end of the opening307.

The rest of the configuration is the same as in the thirty-third embodiment.

In the present embodiment, the heat transfer area with the coolant at the projection306can be increased. Furthermore, the projection306can be easily formed.

Other than this, the present embodiment has the same functions and effects as in the thirty-third embodiment.

As shown inFIG.81, the present embodiment is an embodiment obtained by changing the direction of the projections306of a thirty-sixth embodiment.

Specifically, the projections306are connected to the side wall portion402on the upstream side of the coolant channel330.

Other than this, the present embodiment has the same configuration and functions and effects as in a thirty-sixth embodiment.

As shown inFIG.82, the present embodiment is also an embodiment obtained by changing the direction of the projections306of a thirty-sixth embodiment.

However, in the present embodiment, some of the projections306are connected to the side wall portion402on the downstream side of the coolant channel330.

Specifically, the projections306of the diffusion units305arranged on the upstream side of the coolant channel330are connected to the side wall portion402on the upstream side of the coolant channel330, and the projections306of the diffusion units305arranged on the downstream side of the coolant channel330are connected to the side wall portion402on the downstream side of the coolant channel330.

Other than this, the present embodiment has the same configuration and functions and effects as in a thirty-sixth embodiment.

As shown inFIG.83, the present embodiment is also an embodiment obtained by changing the direction of the projections306of a thirty-sixth embodiment.

However, in the present embodiment, all the projections306are connected to the side wall portion402on the downstream side of the coolant channel330.

Other than this, the present embodiment has the same configuration and functions and effects as in a thirty-sixth embodiment.

As shown inFIG.84, the present embodiment is an embodiment in which the diffusion unit305is not provided with the projection306.

That is, unlike the thirty-third embodiment, the diffusion unit305does not have the projection306. The opening307formed at the side wall portion402constitutes the diffusion unit305. In the present embodiment, the opening307has a substantially rectangular shape.

The rest of the configuration is the same as in the thirty-third embodiment.

In the present embodiment, the diffusion unit305can be simplified. As a result, it is possible to improve the productivity of the component cooling device310and reduce a manufacturing cost.

Other than this, the present embodiment has the same functions and effects as in the thirty-third embodiment.

As shown inFIG.85, the present embodiment is also an embodiment in which the diffusion unit305is not provided with the projection306.

In the present embodiment, the opening307constituting the diffusion unit305has a substantially circular shape.

The rest of the configuration is the same as in a 40th embodiment.

Also the present embodiment has the same functions and effects as in a 40th embodiment.

As shown inFIGS.86and87, the present embodiment is an embodiment in which the diffusion unit305has the opening307that is formed at a part of the internal fin304, and a lid portion308that closes the opening307.

The lid portion308is configured to be elastically deformed when a predetermined pressure in the plate thickness direction is applied to the lid portion308.

Thus, when the predetermined pressure is not applied to the lid portion308, as shown inFIG.86, the opening307is closed by the lid portion308. For example, in the non-boiling state in which the coolant does not boil, the pressure applied to the lid portion308is less than the predetermined pressure, and the opening307is closed by the lid portion308. Accordingly, also in the diffusion unit305, the coolant flows through each branch channel337. Thus, in the diffusion unit305, the coolant flows in each branch channel337without being diffused to another branch channel337.

On the other hand, when the predetermined pressure is applied to the lid portion308, as shown inFIG.87, the lid portion308is elastically deformed and the opening307is opened. For example, in the boiling state in which the coolant boils, the pressure applied to the lid portion308is the predetermined pressure or more, and the lid portion308is elastically deformed in the thickness direction and the opening307is exposed. Thus, in the diffusion unit305, the coolant (particularly vapor) can flow between the branch channels337.

When the boiling state ends and the pressure applied to the lid portion308becomes less than the predetermined pressure, the opening307is closed again by the lid portion308. Thus, the coolant flows again through each branch channel337.

The diffusion unit305may be configured such that when the pressure applied to the lid portion308is less than the predetermined pressure, the opening307is completely closed by the lid portion308or the opening307is not completely closed by the lid portion308. The degree of opening of the opening307when the pressure applied to the lid portion308is less than the predetermined pressure only needs to be smaller than the degree of opening of the opening307when the pressure applied to the lid portion308is the predetermined pressure or more.

The rest of the configuration is the same as in the thirty-third embodiment.

In the present embodiment, in normal times such as in the non-boiling state, the coolant is allowed to flow through each branch channel337. Therefore, the channel resistance can be reduced, and a uniform flow rate of the coolant in the Z direction is easily achieved. As a result, the cooling performance for the electronic component is easily improved as a whole.

Since, when the coolant boils, the diffusion unit305functions as described above, the vapor can be released outward in the Z direction. Therefore, also in the boiling state, the cooling performance can be improved.

Other than this, the present embodiment has the same functions and effects as in the thirty-third embodiment.

In the present embodiment, the shapes of the opening307and the lid portion308may be changed as appropriate.

The above embodiments show an embodiment in which the first electronic component321and the second electronic component322are separately arranged in the respective individual component modules320. However, the component cooling device may be configured such that a first electronic component and a second electronic component are integrated in a single component module and the component module is thermally in contact with a cooling pipe.

The present disclosure has been described in accordance with the embodiments, but it is understood that the present disclosure is not limited to these embodiments or structures. The present disclosure encompasses various modifications and variations in an equivalent range. In addition, the scope and spirit of the present disclosure encompass various combinations or forms and other combinations or forms including only one element, one or more elements, or one or less elements.