Cooling structure for inverter and capacitor accommodated integrally with motor in housing of motor, motor unit with cooling structure, and housing

Inside a housing, there are provided a motor generator (MG), an IPM, and a smoothing capacitor. Between the MG and the IPM, there is provided a cooler through which a coolant liquid flows, provided in an inclined manner to form contact with the top face of the IPM. Between the MG and the smoothing capacitor, there are provided a first communication channel through which an LLC flows from a region outside the housing into the cooler, brought into contact with a lateral face of the smoothing capacitor, and a second communication channel through which the LLC flows from the interior of the cooler to the region outside the housing.

TECHNICAL FIELD

The present invention relates to the cooling technique for an inverter and capacitor accommodated integrally in a housing of a motor, particularly to the technique of suppressing heat transfer from the motor to the inverter and capacitor.

BACKGROUND ART

There is conventionally known an inverter-integrated motor allowing simplification and downsizing of the structure by providing an inverter and motor integrally. In recent years, there is a demand for reducing the size of the inverter-integrated motor since such inverter-integrated motors are now mounted on a vehicle (electric car, hybrid vehicle, or the like) that runs with the motor driven by an alternating current converted by the inverter. Accordingly, there is also the demand for reducing the size of the cooling structure for the motor and inverter. Japanese Patent Laying-Open No. 2003-324903, for example, discloses the approach to reduce the size of a cooling structure for an inverter-integrated motor.

The inverter-integrated motor for a vehicle disclosed in Japanese Patent Laying-Open No. 2003-324903 includes a motor unit accommodated in a housing, and inverter circuitry fixed to the housing, converting direct-current power into three-phase alternating-current power for supply to the motor unit. The inverter circuitry includes a power switching element constituting each arm of a three-phase inverter circuit, a smoothing capacitor connected between a pair of direct-current input terminals of the three-phase inverter circuit, a control circuit controlling the power switching element, and a wiring connecting the switching element, smoothing capacitor, and control circuit. The housing includes a low-pressure coolant gas inlet and a low-pressure coolant gas outlet.

According to the inverter-integrated motor for a vehicle disclosed in Japanese Patent Laying-Open No. 2003-324903, the housing in which the motor is accommodated is cooled by low-pressure coolant gas. The power switching element and the smoothing capacitor constituting the inverter unit are fixed to the housing of the motor. Accordingly, the motor, power switching element, and smoothing capacitor can be cooled by the housing that has been reduced in temperature by the low-pressure coolant gas without having to provide independent cooling structures for respective components. This allows reduction in the size of the cooling structure.

However, the inverter-integrated motor for a vehicle of Japanese Patent Laying-Open No. 2003-324903 is absolutely silent about the specific location of the path of the low-pressure coolant gas. Therefore, in the case where a channel for the coolant is not provided at the housing between the motor and the power switching element, the heat from the motor may not be absorbed by the coolant and be undesirably transferred to the power switching element via the housing. Similarly, in the case where a channel for the coolant is not provided at the housing between the motor and the smoothing capacitor, the heat from the motor may be undesirably transferred to the smoothing capacitor via the housing. There is a possibility of the electronic switching element and smoothing capacitor being degraded in function.

DISCLOSURE OF THE INVENTION

The present invention is directed to solve the problems set forth above. An object of the present invention is to provide a cooling structure for an inverter and capacitor accommodated integrally with a motor in a housing of the motor, capable of blocking heat transfer from the motor to the inverter and capacitor, a motor unit with the cooling structure, and a housing.

The cooling structure of the present invention is directed to a cooling structure for an inverter and a capacitor accommodated integrally with a motor in a housing of the motor. The cooling structure includes a flow channel through which a coolant flows, provided between the motor and the inverter, and a communication channel provided between the motor and the capacitor, establishing communication between the flow channel and a region outside the housing to allow flow of the coolant between the flow channel and the region outside the housing.

In accordance with the present invention, the inverter is cooled by the coolant flowing through the flow channel. This flow channel is located between the motor and the inverter. Therefore, the heat transfer from the motor to the inverter can be blocked intentionally by the flow channel. The coolant flows through the communication channel establishing communication between flow channel and the region outside the housing to dissipate heat by means of, for example, a radiator or the like, provided outside the housing. The communication channel is located between the motor and the capacitor. Therefore, the heat transfer from the motor to the capacitor can be blocked intentionally by the communication channel. Thus, there can be provided a cooling structure for an inverter and capacitor accommodated integrally with a motor in a housing of the motor, capable of blocking heat transfer from the motor to the inverter and the capacitor.

Preferably, the coolant is a liquid coolant. The communication channel is provided upper than the flow channel, establishing communication between the flow channel and the region outside the housing, upper than the flow channel.

According to the present invention, a liquid coolant flows through the flow channel and the communication channel. The flow channel establishes communication with the region outside the housing, upper than the flow channel, through the communication channel. Accordingly, the air introduced into the flow channel can be elevated in the communication channel to be discharged outside the housing. Therefore, degradation in the cooling performance caused by the air accumulated in the flow channel and communication channel can be suppressed.

Further preferably, the flow channel is provided below the motor in an inclined manner. The communication channel is provided at a lateral side of the motor, establishing communication between an upper end portion of the flow channel and the region outside the housing.

The inclination of the flow channel in the present invention allows the air introduced in the flow channel to be elevated to the upper end portion of the flow channel. The air elevated to the upper end portion of the flow channel is further elevated through the communication channel to be discharged outside the housing. Therefore, accumulation of air in the flow channel can be suppressed more reliably.

Further preferably, the flow channel further includes an outlet through which a coolant is discharged, provided at a lower end portion of the flow channel.

According to the present invention, the outlet of the coolant is provided at the lower end portion of the flow channel. Therefore, the liquid coolant in the flow channel and communication channel can be discharged by its own weight by opening the drain outlet. Therefore, at the time of exchanging the coolant, the event of the coolant persistently remaining in the flow channel and communication channel can be suppressed.

Further preferably, the communication channel includes a first communication channel through which a coolant flows from the region outside the housing into the flow channel, and a second communication channel provided closer to the motor than the first communication channel, and through which the coolant flows from the flow channel out to the region outside the housing.

According to the present invention, the second communication channel through which the coolant in the flow channel absorbing the heat from the inverter and motor flows to the region outside the housing is provided closer to the motor than the first communication channel through which the coolant outside the housing flows into the flow channel. Accordingly, the heat from the motor will not be transferred to the capacitor as long as passage through the second communication channel and the first communication channel is avoided. Therefore, the heat transfer from the motor to the capacitor can be blocked more reliably. Further, the coolant absorbing the heat from the inverter and motor will not flow to the first communication channel provided at the capacitor side. Therefore, transfer of the heat from the inverter and motor towards the capacitor through the coolant can be suppressed.

Further preferably, the flow channel includes a first flow channel brought into contact with the inverter, and a second flow channel provided closer to the motor than the first flow channel, at a downstream side of the first flow channel.

According to the present invention, the second flow channel located downstream of the first flow channel that brought into contact with the inverter is provided closer to the motor than the first flow channel. Therefore, the heat from the motor will not be transferred to the inverter capacitor as long as passage through the second flow channel and the first flow channel is avoided. Accordingly, the transfer of heat from the motor towards the inverter can be blocked more reliably. Further, the first flow channel in contact with the inverter is located at an upstream side of the second flow channel. Therefore, the temperature of the coolant flowing through the first flow channel in contact with the inverter can be set lower than the temperature of the coolant flowing through the second flow channel, allowing the inverter to be cooled more efficiently.

A motor unit according to the present invention includes a housing in which a motor, an inverter, and a capacitor are accommodated integrally. The motor unit includes a flow channel through which a coolant flows, provided between the motor and the inverter, and a communication channel provided between the motor and the capacitor, establishing communication between the flow channel and a region outside the housing to allow flow of the coolant between the flow channel and the region outside the housing.

According to the present invention, the inverter is cooled by the coolant flowing through the flow channel. This flow channel is located between the motor and the inverter. Therefore, the heat transfer from the motor to the inverter can be blocked intentionally by the flow channel. The coolant flows through the communication channel establishing communication between the flow channel and the region outside the housing, and dissipates heat by, for example, a radiator or the like, provided outside the housing. This communication channel is located between the motor and the capacitor. Therefore, the heat transfer from the motor to the capacitor can be blocked intentionally by the communication channel. Thus, there can be provided a motor unit including a housing in which a motor, an inverter, and a capacitor are accommodated integrally, allowing heat transfer from the motor to the inverter and capacitor to be blocked.

A housing according to the present invention accommodates a motor, an inverter, and a capacitor integrally. The housing includes a motor casing in which a motor is accommodated, an inverter casing in which an inverter is accommodated, a capacitor casing in which a capacitor is accommodated, a flow channel through which a coolant flows, provided between the motor casing and the inverter casing, and a communication channel provided between the motor casing and the capacitor casing, establishing communication between the flow channel and a region outside the housing to allow flow of the coolant between the flow channel and the region outside the housing.

According to the present invention, the inverter is cooled by the coolant flowing through the flow channel. This flow channel is provided between the motor and the inverter. Therefore, the heat transfer from the motor to the inverter can be blocked intentionally by the flow channel. The coolant flows through the communication channel establishing communication between the flow channel and the region outside the housing to dissipate heat by, for example, a radiator or the like, provided outside the housing. The communication channel is located between the motor and the capacitor. Therefore, the heat transfer from the motor to the capacitor can be blocked intentionally by the communication channel. Thus, there can be provided a housing in which a motor, an inverter, and a capacitor are accommodated integrally, allowing heat transfer from the motor towards the inverter and capacitor to be blocked.

BEST MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described hereinafter with reference to the drawings. In the following, the same components have the same reference characters allotted. Their designation and function are also identical. Therefore, detailed description thereof will not be repeated.

A configuration of a vehicle incorporating a motor unit10with a cooling structure according to the present embodiment will be described with reference toFIG. 1. Although the present embodiment will be described based on an electric car running only by the driving force from motor unit10as the vehicle, the vehicle mounted with a cooling structure for a capacitor according to the present invention is not limited to an electric car, and may be applied to a hybrid vehicle. Further, the present invention is not particularly limited to motor unit10for driving a vehicle.

The vehicle includes a motor unit10providing a driving force by the power supplied from a battery (not shown), and a radiator600. Motor unit10includes a motor generator (MG)100, an IPM (Intelligent Power Module)200, a smoothing capacitor300, a cooler400, a first communication channel500, a second communication channel550, and a housing110in which all these components are accommodated.

MG100functions as a three-phase alternating-current motor, and also as generator generating power in a vehicle regenerative braking mode. MG100is accommodated in a motor casing112provided in housing110. MG100has its rotational shaft eventually connected to the drive shaft (not shown) of the vehicle. The vehicle runs by the driving force from MG100. MG100generates heat during operation as a motor or generator.

IPM200is formed having a shape of substantially a rectangular solid, including a plurality of IGBTs (Insulated Gate Bipolar Transistor) constituting the inverter, and a control substrate on which are mounted electronic components controlling the ON/OFF (energization/shut down) of the gate of each of IGBT (not shown). IPM200causes MG100to function as a motor or generator based on a control signal from an ECU (not shown). IPM200generates heat by the ON/OFF of the gate of each IGBT.

IPM200is accommodated in an inverter casing114provided in housing110and below motor casing112. Inverter casing114is provided in an inclined manner such that the front side corresponding to front direction of the vehicle is located higher under a state where housing110is fixed to the vehicle. Inverter casing114has its bottom portion open, and is sealed by a lid120.

Smoothing capacitor300is formed having a shape of substantially a rectangular solid, connected to IPM200by an electrode line310. Smoothing capacitor300temporarily stores charge in order to smooth the power from the battery for supply to IPM200, or to smooth the power from IPM200for supply to the battery. Thus, occurrence of inrush current towards IPM200is prevented.

Smoothing capacitor300is accommodated in capacitor casing116provided at the vehicle front side direction than motor casing112, along the direction of the lateral side of housing110. Accordingly, IPM200and smoothing capacitor300are provided to be substantially orthogonal. Further, the lower portion of capacitor casing116communicates with the vehicle front side of inverter casing114such that the upper portion of IPM200and the lower portion of smoothing capacitor300are adjacent. Likewise with inverter casing114, the bottom portion of capacitor casing116is open, and sealed by lid120.

Cooler400is a metal plate located between MG100and IPM200, provided in an inclined manner to contact the top face of IPM200. A flow channel for a cooling liquid (hereinafter, also referred to as LLC (Long Life Coolant)) is provided in cooler400for the passage of coolant liquid.

At the upper end portion of cooler400are connected a first communication channel500and a second communication channel550. Further, an outlet402is provided at the lower end portion of cooler400.

First and second communication channels500and550are provided between MG100and smoothing capacitor300, brought into contact with a side face of smoothing capacitor300, establishing communication between cooler400and a region outside housing110. The LLC flows through first communication channel500from the region outside housing110into cooler400. The LLC flows through second communication channel550from the interior of cooler400to the region outside housing110.

Outlet402is provided with a cap404at the lower end. By opening cap404at the time of exchanging the LLC, the LLC in cooler400, first communication channel500and second communication channel550is discharged outside housing110by its own weight.

Radiator600is a device transferring the heat of the LLC outside. Radiator600is provided upper than motor unit10and at a vehicle front side direction. Radiator600is connected to first communication channel500through a circulation path610, and is connected to second communication channel550through a circulation path620. The LLC is circulated between radiator600and cooler400through circulation paths610and620by an electric water pump (not shown).

Cooler400, first communication channel500and second communication channel550will be described with reference toFIGS. 2 and 3.FIG. 2is a skiagram of cooler400, first communication channel500and second communication channel550, viewed from above in a direction perpendicular to the top face of IPM200.FIG. 3is a skiagram of cooler400, first communication channel500and second communication channel550, viewed from the vehicle front side in a direction parallel to the top face of IPM200.

A flow inlet502, flow-in paths510and512, and connection openings520and522constitute first communication channel500.

Flow inlet502is provided at the upper end of first communication channel500, connected with circulation path610. The LLC cooled at radiator600flows from circulation path610towards flow inlet502. First communication channel500has its upper end protruding from housing110, at the top face of housing110at the vehicle front side in order to reduce the distance from radiator600and shorten the length of circulation path610.

First communication channel500is divided into flow-in path510and flow-in path512from inlet502towards the downstream side. Flow-in path510and flow-in path512are connected to the upper end portion of cooler400through connection openings520and522, respectively, provided at their lower ends.

Second communication channel550is located at the right side of the vehicle with respect to first communication channel500. A flow outlet552, flow-out paths560and562, and connection openings570and572constitute second communication channel550.

Flow-out path560and flow-out path562are connected to the upper end portion of cooler400through connection openings570and572, respectively, located at their lower ends. Flow-out path560and flow-out path562are connected so as to merge midway before arrival at flow outlet552.

Flow outlet552is provided at the upper end of second communication channel550, and is connected with circulation path620. The LLC running through cooler400flows out from flow outlet552towards circulation path620. Second communication channel550has its upper end protruding from housing110, at the top face of housing110at the vehicle front side in order to reduce the distance from radiator600and shorten the length of circulation path620.

A flow channel through which the LLC flowing in via connection openings520and522is circulated and discharged from connection openings570and572is formed inside cooler path400.

The action of the cooling structure according to the present embodiment will be described based on the structure set forth above. When MG100is driven, heat is generated from MG100and IPM200.

Cooler400through which the LLC flows is provided between MG100and IPM200, brought into contact with the top face of IPM200. As shown inFIG. 4, the heat from IPM200is absorbed by the LLC circulating the interior of cooler400, whereby IPM200is cooled. Further, the heat generated from MG100is transferred to cooler400via housing110, as shown inFIG. 4. Therefore, the heat transfer from MG100towards IPM200can be blocked intentionally by cooler path400.

The LLC in cooler400is circulated to and from radiator600through first communication channel500and second communication channel550. These first and second communication channels500and550are located between MG100and smoothing capacitor300. Therefore, the heat from MG100transferred to housing110is partially absorbed by the LLC flowing through first communication channel500and second communication channel550, as shown inFIG. 4. Accordingly, the heat transfer from MG100towards smoothing capacitor300can be blocked intentionally by first and second communication channels500and550.

Further, cooler400is provided in an inclined manner to contact the top face of IPM200. The upper end of cooler400is connected with first communication channel500and second communication channel550. Therefore, even in the case where air is introduced into cooler400, the air will escape to first and second communication channels500and550through connection openings520,522,570and572. The air in first and second communication channels500and550is further elevated to be discharged outside housing110through flow inlet502and outlet552. Accordingly, the accumulation of air at cooler400and/or first and second communication channels500and550can be suppressed reliably. Therefore, degradation in the cooling performance of IPM200can be suppressed, and the heat transfer from MG100towards IPM200and smoothing capacitor300can be blocked more efficiently.

According to the cooling structure of the present embodiment, the cooler through which the LLC flows is provided between the motor generator and IPM. In addition, the communication channel through which the LLC inside the cooler passes during circulation to and from the radiator is provided between the motor generator and the smoothing capacitor. Therefore, the heat transfer from the motor generator to the IPM and the smoothing capacitor can be blocked intentionally by virtue of the cooler and communication channels.

A motor unit1010with a cooling structure of the present embodiment will be described with reference toFIG. 5. Motor unit1010of the present embodiment differs in configuration from motor unit10of the first embodiment set forth above in that cooler400, first communication channel500and second communication channel550are replaced with a cooler1400, a first communication channel1500, and a second communication channel1550. The remaining configuration is similar to that of the vehicle in the previous first embodiment. The same elements have the same reference characters allotted. Their functions are also identical. Therefore, detailed description thereof will not be repeated.

Cooler1400is a metal plate provided between MG100and IPM200in an inclined manner. A first flow channel1410and a second flow channel1420through which the LLC passes are provided in cooler1400. First flow channel1410is provided to form contact with the top face of IPM200. Second flow channel1420is provided at a downstream side of first flow channel1410, along the top face of first flow channel1410, closer to MG100than first flow channel1410.

First communication channel1500is provided to form contact with a lateral side of smoothing capacitor300, having the upper end and lower end connected to circulation path610and first flow channel1410, respectively.

Second communication channel1550is provided along the lateral face of first communication channel1500, closer to MG100than first communication channel1500, and having the upper end and lower end connected to circulation path620and second flow channel1420, respectively.

First communication channel1500and second communication channel1550will be described with reference toFIGS. 6 and 7.FIG. 6is a skiagram of cooler1400, first communication channel1500and second communication channel1550, viewed from above in a direction perpendicular to the top face of IPM200.FIG. 7is a skiagram of cooler1400, first communication channel1500and second communication channel1550, viewed from the vehicle front side in a direction parallel to the top face of IPM200.

First communication channel1500is connected to circulation path610at a flow inlet1502provided at the upper end, and is connected to the upper end of first flow channel1410at a connection opening1520provided at the lower end. First communication channel1500is formed such that the area of contact with the side face of smoothing capacitor300increases from the side of flow inlet1502towards the side of connection opening1520corresponding to the downstream side.

Second communication channel1550is connected to circulation path620at a flow outlet1552provided at the upper end, and is connected to the upper end portion of second flow channel1420at a connection opening1570located at the lower end. Second communication channel1550is formed to match the side face of first communication channel1500.

The function of the cooling structure according to the present embodiment based on the structure set forth above will be described. Cooler1400is provided between MG100and IPM200. In addition, first and second communication channels1500and1550are provided between MG100and smoothing capacitor300. Therefore, likewise with the first embodiment, the heat transfer from MG100towards IPM200and smoothing capacitor300can be blocked intentionally.

Second communication channel1550is provided closer to MG100than first communication channel1500. Therefore, the heat from MG100will not be transferred to smoothing capacitor300as long as passage through second communication channel1550and first communication channel1500is avoided. Therefore, the heat transfer from MG100to smoothing capacitor300can be blocked more reliably. In addition, as shown inFIG. 8, the LLC absorbing the heat from IPM200and MG100will not flow through first communication channel1500in contact with smoothing capacitor300since the LLC flows outside housing110through second communication channel1550. Therefore, the transfer of heat from IPM200and MG100to smoothing capacitor300via the LLC can be suppressed.

In addition, cooler1400has the interior divided into second flow channel1420and first flow channel1410. Second flow channel1420provided at the downstream side of first flow channel1410is provided closer to MG100than first flow channel1410. Accordingly, the heat from MG100will not be transferred to IPM200as long as passage through second flow channel1420and first flow channel1410is avoided. Therefore, the heat transfer from MG100towards IPM200can be blocked more reliably. Further, as shown inFIG. 8, first flow channel1410in contact with IPM200is located at an upstream side of second flow channel1420. Therefore, the temperature of the LLC flowing through first flow channel1410can be set lower than the temperature of the LLC flowing through second flow channel1420, allowing IPM200to be cooled more efficiently.

Further, first communication channel1500is formed such that the area of contact with the side face of smoothing capacitor300is increased from inlet1502towards the downstream side. Therefore, more heat transfer from MG100towards smoothing capacitor300can be blocked.

According to the cooling structure of the present embodiment, the cooler is provided between the motor generator and IPM, and a communication channel is provided between the motor generator and smoothing capacitor. Therefore, the heat transfer from the motor generator towards the IPM and smoothing capacitor can be blocked intentionally, likewise with the first embodiment. Further, the flow channel at the downstream side in the cooler is located closer to the motor generator than the flow channel at the upstream side, and the second communication channel is located closer to the motor generator than the first communication channel. Accordingly, the heat transfer from the motor generator to the IPM and smoothing capacitor can be blocked more reliably.