VEHICULAR REFRIGERATION CYCLE UNIT

A vehicular refrigeration cycle unit is a vehicular refrigeration cycle unit installed between a vehicle exterior heat exchanger and a vehicle interior heat exchanger and exchanging heat between secondary refrigerants respectively flowing through the vehicle exterior heat exchanger and the vehicle interior heat exchanger, the vehicular refrigeration cycle unit including: a refrigeration cycle including a compressor, a condenser, an expansion valve, and an evaporator through which a primary refrigerant sequentially flows; an exterior flow passage through which the secondary refrigerant is circulated between the evaporator and the vehicle exterior heat exchanger; an interior flow passage through which the secondary refrigerant is circulated between the condenser and the vehicle interior heat exchanger; a pair of flow passage switching valves connecting the exterior flow passage and the interior flow passage to allow to switch the flow state of the second refrigerant between the exterior flow passage and the interior flow passage; a first bypass flow passage which is installed aside the exterior flow passage and with bypassing the evaporator; and a first flow rate adjustment unit adjusting a flow rate of the secondary refrigerant flowing into the evaporator.

TECHNICAL FIELD

Background Art

In vehicles such as electric automobiles that are not equipped with generators (engines), a secondary refrigerant type heat pump system is used as a heat source for an air conditioner (heating). The secondary refrigerant type heat pump system mainly includes a vehicle exterior heat exchanger which is connected to an evaporator of a refrigeration cycle allowing a primary refrigerant to flow therethrough and through which a secondary refrigerant flows and a vehicle interior heat exchanger which is connected to a condenser side of the refrigeration cycle and through which the secondary refrigerant flows. The heat of the secondary refrigerant heated by the exterior air is transferred to the vehicle interior heat exchanger via the refrigeration cycle. Accordingly, it is possible to heat the interior air.

Incidentally, in the heat pump system, sufficient pressure of the primary refrigerant cannot be obtained even when heat is absorbed from outside air under a condition that an outside air temperature is very low. As a result, there was a problem that a compressor of the refrigeration cycle was not able to generate a sufficient flow rate of the refrigerant. Here, a device according to Patent Document 1 below adopts a configuration in which a secondary refrigerant flowing through a vehicle interior heat exchanger (that is, a condenser side) flows while being mixed at an evaporator side of a refrigeration cycle. Accordingly, it is said that the pressure of a primary refrigerant heading to a compressor via the evaporator can be increased.

CITATION LIST

Patent Document

SUMMARY OF INVENTION

Technical Problem

However, it is difficult to precisely control the temperature of the secondary refrigerant only in the configuration in which the secondary refrigerant simply flows while being mixed at the evaporator side as described above.

The present disclosure has been made to solve the above-described problems and an object thereof is to provide a vehicular refrigeration cycle unit capable of more precisely adjusting a temperature of a secondary refrigerant.

Solution to Problem

In order to solve the above-described problems, a vehicular refrigeration cycle unit according to the present disclosure is a vehicular refrigeration cycle unit which is installed between a vehicle exterior heat exchanger and a vehicle interior heat exchanger and exchanging heat between secondary refrigerants respectively flowing through the vehicle exterior heat exchanger and the vehicle interior heat exchanger, the vehicular refrigeration cycle unit including: a refrigeration cycle including a compressor, a condenser, an expansion valve, and an evaporator through which a primary refrigerant sequentially flows; an exterior flow passage through which the secondary refrigerant is circulated between the evaporator and the vehicle exterior heat exchanger; an interior flow passage through which the secondary refrigerant is circulated between the condenser and the vehicle interior heat exchanger; a pair of flow passage switching valves connecting the exterior flow passage and the interior flow passage to allow to switch a flow state of the second refrigerant between the exterior flow passage and the interior flow passage; a first bypass flow passage which is aside the exterior flow passage with bypassing the evaporator; and a first flow rate adjustment unit adjusting a flow rate of the secondary refrigerant flowing into the first bypass flow passage and the evaporator, wherein the first flow rate adjustment unit is a flow passage switching valve distributing the secondary refrigerant flowing from one flow passage into two flow passages and is allowed to change a ratio of a flow rate of the secondary refrigerant between these two flow passages.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide a vehicular refrigeration cycle unit capable of more precisely adjusting a temperature of a secondary refrigerant.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Configuration of Vehicular Refrigeration Cycle Unit

Hereinafter, a vehicular refrigeration cycle unit1according to a first embodiment of the present disclosure will be described with reference toFIGS.1to5.

The vehicular refrigeration cycle unit1according to this embodiment is air conditioning equipment installed in a transportation vehicle such as an electric vehicle that does not have an engine as a heat source during heating. The vehicular refrigeration cycle unit1is mounted to be interposed between a vehicle exterior heat exchanger10disposed on a vehicle exterior side and a vehicle interior heat exchanger20disposed on a vehicle interior side. The refrigerant (coolant) flowing through the vehicle exterior heat exchanger10and the vehicle interior heat exchanger20is hereinafter referred to as a “secondary refrigerant” and the refrigerant flowing through a refrigeration cycle30(described later) is referred to as a “primary refrigerant”.

As shown inFIG.1, the vehicular refrigeration cycle unit1includes the refrigeration cycle30through which the primary refrigerant flows, an exterior flow passage40which is disposed on an exterior side, an interior flow passage50which is disposed on an interior side, a pair of flow passage switching valves60which switches the mutual flow state of the exterior flow passage40and the interior flow passage50, a first bypass flow passage41which is alongside the exterior flow passage40, a first flow rate adjustment unit42, a second bypass flow passage51which is alongside the interior flow passage50, a second flow rate adjustment unit52, a first pump43which is provided on the exterior flow passage40, a second pump53which is provided on the interior flow passage50, an exterior connection flow passage44, a first switching valve45, an interior connection flow passage54, a second switching valve55, a measurement unit46, and a control unit90.

Additionally, in the drawings, if various valves of the vehicular refrigeration cycle unit1are painted black, they are in a closed state and if these valves are painted white, they are in an open state. Further, the directions in which various refrigerants flow are indicated by arrows drawn along the circuits.

Configuration of Refrigeration Cycle

The refrigeration cycle30is composed of a plurality of devices that realize a thermodynamic cycle. The refrigeration cycle30is a refrigerant circuit that allows the primary refrigerant as a heat medium to sequentially flow and circulate in a plurality of devices while repeatedly compressing, expanding, evaporating, and condensing the primary refrigerant in order to exchange heat between the primary refrigerant and the secondary refrigerant.

The refrigeration cycle30includes a refrigeration cycle line31and a compressor32, a condenser33, an expansion valve34, and an evaporator35sequentially arranged on this refrigeration cycle line31.

The evaporator35is a plate heat exchanger that evaporates (vaporizes) the primary refrigerant by exchanging heat between the primary refrigerant sequentially flows through the refrigeration cycle30and the secondary refrigerant introduced from the outside of the refrigeration cycle30. The primary refrigerant inside the evaporator35absorbs heat from the secondary refrigerant and simultaneously cools the secondary refrigerant.

The compressor32is a device that absorbs heat and compresses the vaporized primary refrigerant by passing through the evaporator35. The pressure of the primary refrigerant introduced into the compressor32is increased to a predetermined pressure higher than before compression by the compression operation of the compressor32. Accordingly, the temperature of the primary refrigerant becomes higher than before compression.

The condenser33is a plate heat exchanger that condenses (liquefies) the primary refrigerant by exchanging heat between the primary refrigerant passing through the compressor32to have a temperature and a pressure higher than before compression and the secondary refrigerant introduced from the outside of the refrigeration cycle30.

The primary refrigerant inside the condenser33is cooled by the secondary refrigerant and simultaneously increases the temperature of the secondary refrigerant.

The primary refrigerant in a gas state introduced into the condenser33is cooled by the secondary refrigerant, passes through a two-phase state of a gas-liquid mixture, and then transitions to a liquid state.

The expansion valve34is a device that receives the primary refrigerant changing into a liquid state via the condenser33and adiabatically expands the primary refrigerant. The pressure of the primary refrigerant introduced to the expansion valve34is decreased to a predetermined pressure lower than before expansion due to the expansion action of the expansion valve34. Accordingly, the temperature of the primary refrigerant becomes lower than before expansion.

Configuration of Exterior Flow Passage, First Switching Valve, First Pump, and Exterior Connection Flow Passage

The exterior flow passage40is a flow passage that connects the evaporator35in the refrigeration cycle30and the vehicle exterior heat exchanger10in an annular shape. The secondary refrigerant flows through the exterior flow passage40. The first pump43, the first switching valve45, and the exterior connection flow passage44are provided on the exterior flow passage40. The first pump43pressure-feeds the secondary refrigerant flowing through the exterior flow passage40. The first switching valve45is a three-way valve that can switch the flow state between three flow passages. The exterior connection flow passage44extends with bypassing the vehicle exterior heat exchanger10from the first switching valve45as a start point. The first switching valve45is electrically connected to the control unit90to be described later and the flow state of the secondary refrigerant is switched by the electric signal sent from the control unit90.

Configuration of First Bypass Flow Passage and First Flow Rate Adjustment Unit

The first bypass flow passage41is provided alongside the exterior flow passage40and extends with bypassing the evaporator35. A flow rate adjustment valve70is provided at one end of the first bypass flow passage41as the first flow rate adjustment unit42. The flow rate adjustment valve70is a three-way valve. That is, the flow rate adjustment valve70can distribute the secondary refrigerant flowing from one flow passage into two flow passages and change the ratio of the flow rate of the secondary refrigerant between these two flow passages.

Specifically, the first flow rate adjustment unit42changes the ratio of the flow rate of the secondary refrigerant flowing into the evaporator35via the exterior flow passage40and the flow rate of the secondary refrigerant flowing into the first bypass flow passage41. The ratio of the flow rate is realized by changing the internal structure of the valve of the flow rate adjustment valve70. The flow rate adjustment valve70is electrically connected to the control unit90(to be described later). The internal structure of the valve is controlled based on the electric signal sent from the control unit90.

Configuration of Interior Flow Passage, Second Switching Valve, Second Pump, and Interior Connection Flow Passage

The interior flow passage50is a flow passage that connects the condenser33in the refrigeration cycle30and the vehicle interior heat exchanger20in an annular shape. The secondary refrigerant flows through the interior flow passage50. The second pump53, the second switching valve55, and the interior connection flow passage54are provided on this interior flow passage50. The second pump53pressure-feeds the secondary refrigerant flowing through the interior flow passage50. The second switching valve55is a three-way valve similarly to the first switching valve45. The second switching valve55is electrically connected to the control unit90to be described later and the flow state of the secondary refrigerant is switched by the electric signal sent from the control unit90. The interior connection flow passage54extends with bypassing the vehicle interior heat exchanger20from the second switching valve55as a start point.

Configuration of Second Bypass Flow Passage and Second Flow Rate Adjustment Unit

The second bypass flow passage51is provided alongside the interior flow passage50and extends with bypassing the condenser33. The flow rate adjustment valve70is provided at one end of the second bypass flow passage51as the second flow rate adjustment unit52. The flow rate adjustment valve70is a three-way valve. That is, the flow rate adjustment valve70can distribute the secondary refrigerant flowing from one flow passage into two flow passages and change the ratio of the flow rate of the secondary refrigerant between these two flow passages.

Specifically, the second flow rate adjustment unit52changes the ratio of the flow rate of the secondary refrigerant flowing into the condenser33via the interior flow passage50and the flow rate of the secondary refrigerant flowing into the second bypass flow passage51. The ratio of the flow rate is controlled based on the electric signal sent from the control unit90similarly to the first flow rate adjustment unit42.

The exterior flow passage40and the interior flow passage50are connected by the pair of flow passage switching valves60(a first flow passage switching valve61and a second flow passage switching valve62). More specifically, the first flow passage switching valve61is provided between the vehicle exterior heat exchanger10in the exterior flow passage40and the first flow rate adjustment unit42and between the vehicle interior heat exchanger20in the interior flow passage50and the second flow rate adjustment unit52. Further, the second flow passage switching valve62is provided between the first switching valve45in the exterior flow passage40and the first pump43and between the second switching valve55in the interior flow passage50and the second pump53.

As will be described later, the flow state of the secondary refrigerant between the exterior flow passage40and the interior flow passage50is mutually switched by providing the first flow passage switching valve61and the second flow passage switching valve62. The first flow passage switching valve61and the second flow passage switching valve62are electrically connected to the control unit90(to be described later) and the flow state is switched based on the electric signal sent from the control unit90.

Configuration of Measurement Unit

The measurement unit46measures a physical quantity related to the pressure of the primary refrigerant on the downstream side of the evaporator35in the refrigeration cycle line31. Additionally, the physical quantity mentioned herein may be the pressure of the primary refrigerant itself or the temperature of the primary refrigerant. That is, the measurement unit46is a pressure gauge or a thermometer. The physical quantity measured by the measurement unit46is sent to the control unit90as the electric signal. The control unit90adjusts the flow state of the first flow rate adjustment unit42based on the measurement result of the measurement unit46.

Process Flow of Control Unit

Next, the process flow of the control of the first flow rate adjustment unit42using the control unit90will be described with reference toFIG.5. First, in step S100, it is determined whether or not the control using the control unit90is in an on state. In the case of an off state (step S100: No), the process ends. In the case of an on state (step S100: Yes), the control unit90acquires a physical quantity p related to the pressure of the primary refrigerant from the measurement unit46in step S101below. Next, in step S102, the control unit90determines the magnitude relationship between the physical quantity p and the threshold value. When it is determined that the physical quantity p is larger than the threshold value (step S102: Yes), the process proceeds to step S103. In step S103, the control unit90sends an electric signal to the first flow rate adjustment unit42(the flow rate adjustment valve70) so that the flow rate of the secondary refrigerant flowing into the evaporator35changes in a decrease direction. On the other hand, when it is determined that the physical quantity p is smaller than the threshold value (step S102: No), the process proceeds to step S104. In step S104, the control unit90sends an electric signal to the first flow rate adjustment unit42(the flow rate adjustment valve70) so that the flow rate of the secondary refrigerant flowing into the evaporator35changes in an increase direction. In this way, the flow state of the first flow rate adjustment unit42is controlled based on the physical quantity of the primary refrigerant flowing out from the evaporator35.

Operation and Effect

Next, two operation modes during a heating operation among various operation modes of the vehicular refrigeration cycle unit1will be described. During the heating operation, the operation mode is appropriately selected between a heater mode that is used when the outside air temperature is particularly low (for example, about −20° C.) and a heat pump mode that is used when the outside air temperature is higher than that of the heater mode.

Operation of Heat Pump Mode

First, the operation of the heat pump mode during the heating operation will be described with reference toFIG.2. As shown in the same drawing, the flow state of the first flow passage switching valve61and the second flow passage switching valve62is switched so that the exterior flow passage40and the interior flow passage50are independent of each other in this mode. Further, the exterior connection flow passage44and the interior connection flow passage54are respectively closed by the first switching valve45and the second switching valve55. The first bypass flow passage41and the second bypass flow passage51are respectively closed by the first flow rate adjustment unit42and the second flow rate adjustment unit52.

Accordingly, the secondary refrigerant flows through the path indicated by the arrow inFIG.2. Specifically, in the exterior flow passage40, the secondary refrigerant passing through the second flow passage switching valve62via the first pump43flows into the vehicle exterior heat exchanger10and then flows toward the first flow passage switching valve61. Then, the secondary refrigerant flows into the evaporator35via the first flow rate adjustment unit42. The secondary refrigerant exchanging heat with the primary refrigerant of the refrigeration cycle30in the evaporator35is in a low temperature state. The secondary refrigerant flowing out from the evaporator35flows into the first pump43again. Such a flow occurs continuously.

In the interior flow passage50, the secondary refrigerant passing through the second flow passage switching valve62via the second pump53exchanges heat with interior air in the vehicle interior heat exchanger20. Accordingly, the secondary refrigerant becomes a low temperature state and flows toward the first flow passage switching valve61. Then, the secondary refrigerant flows to the condenser33via the second flow rate adjustment unit52. The secondary refrigerant exchanging heat with the primary refrigerant in the condenser33becomes a high temperature state. The secondary refrigerant flowing out from the condenser33flows into the second pump53again. Such a flow occurs continuously.

With the above-described state, heat is exchanged between the primary refrigerant and the secondary refrigerant. Specifically, heat is exchanged between the relatively high-temperature outside air and the relatively low-temperature secondary refrigerant in the vehicle exterior heat exchanger10. The heat of the secondary refrigerant heated by heat exchange with the outside air is transferred to the secondary refrigerant in the interior flow passage50via the refrigeration cycle30. The secondary refrigerant in the interior flow passage50exchanges heat with the interior air in the vehicle interior heat exchanger20. Accordingly, the interior temperature increases.

Operation of Heater Mode

On the other hand, the open and close states of various valves and the flow state of the secondary refrigerant are as shown inFIG.3during a stationary operation of the heater mode. Specifically, the exterior connection flow passage44is opened by the first switching valve45and the secondary refrigerant flows with bypassing the vehicle exterior heat exchanger10. In the first flow passage switching valve61, the flow state is switched so that the secondary refrigerant flowing through the interior flow passage50flows into the exterior flow passage40and the secondary refrigerant flowing through the exterior flow passage40flows into the interior flow passage50. In the second flow passage switching valve62, the flow state is switched so that the secondary refrigerant discharged from the first pump43flows through the exterior flow passage40and the secondary refrigerant discharged from the second pump53flows through the interior flow passage50.

In the first flow rate adjustment unit42, the secondary refrigerant which flows from the interior flow passage50into the exterior flow passage40via the first flow passage switching valve61is distributed to the side of the evaporator35and the side of the first bypass flow passage41. The ratio of the flow rate of the secondary refrigerant flowing through the evaporator35and the flow rate of the secondary refrigerant flowing through the first bypass flow passage41is controlled by the above-described control flow.

In the second flow rate adjustment unit52, the secondary refrigerant which flows from the exterior flow passage40into the interior flow passage50via the first flow passage switching valve61is controlled to flow not to the second bypass flow passage51but to the condenser33.

Accordingly, the secondary refrigerant flows through the path indicated by the arrow inFIG.3. Specifically, the secondary refrigerant discharged from the first pump43flows toward the first switching valve45via the second flow passage switching valve62on the side of the evaporator35. The secondary refrigerant flowing into the exterior connection flow passage44via the first switching valve45flows into the interior flow passage50via the first flow passage switching valve61. The secondary refrigerant flowing into the interior flow passage50flows into the condenser33via the second flow rate adjustment unit52. The secondary refrigerant that exchanges heat with the primary refrigerant in the condenser33becomes a high temperature state and flows into the second pump53. The secondary refrigerant discharged from the second pump53flows through the interior flow passage50again via the second flow passage switching valve62and heads toward the vehicle interior heat exchanger20.

The secondary refrigerant that exchanges heat with the interior air in the vehicle interior heat exchanger20becomes a low temperature state and heads toward the first flow passage switching valve61through the interior flow passage50. The secondary refrigerant flowing into the exterior flow passage40via the first flow passage switching valve61is distributed to the flow toward the evaporator35and the flow toward the first bypass flow passage41via the first flow rate adjustment unit42. In the evaporator35, heat is exchanged between the secondary refrigerant and the primary refrigerant. Accordingly, the secondary refrigerant becomes a low-temperature state. These two flows merge on the downstream side of the evaporator35and then heads toward the first pump43. The above-described flow of the secondary refrigerant continuously occurs.

With the above-described state, the relatively high-temperature secondary refrigerant flows from the interior flow passage50into the evaporator35. Accordingly, the temperature of the primary refrigerant in the refrigeration cycle30that exchanges heat with the secondary refrigerant increases. As the temperature increases, the pressure and density of the primary refrigerant also increase. Since the density of the primary refrigerant increases, the load of the compressor32also increases. In other words, the work amount of the compressor32increases. As a result, the amount of heat generated in accordance with the operation of the compressor32increases. This increased amount of heat is transferred to the primary refrigerant and then transferred to the secondary refrigerant flowing through the interior flow passage50in the condenser33on the downstream side of the compressor32. Accordingly, the temperature of the secondary refrigerant increases. The heated secondary refrigerant exchanges heat with the interior air in the vehicle interior heat exchanger20. As a result, the interior temperature increases (heating occurs).

In this way, since it is possible to heat the primary refrigerant by the amount of heat due to the increased load of the compressor32, it is possible to secure heating capacity without exchanging heat between the outside air and the secondary refrigerant using the vehicle exterior heat exchanger10. Thus, there is no need to exchange heat between the secondary refrigerant and the outside air while the outside air temperature is too low. In other words, there is no need to make the temperature of the secondary refrigerant flowing through the exterior flow passage40lower than the outside air temperature. As a result, it is possible to perform the heating operation beyond the restriction imposed by the minimum temperature determined by the physical property values of the primary refrigerant.

Furthermore, since the pressure of the primary refrigerant flowing into the compressor32increases as described above, the compression ratio of the compressor32decreases. That is, the Mollier diagram in this case becomes the graph indicated by the solid line inFIG.4. Additionally, the dashed line inFIG.4indicates the Mollier diagram in the heat pump mode. When operating in the heater mode, the pressure shown on the vertical axis increases compared to the heat pump mode and the difference between the upper limit and the lower limit decreases compared to the heat pump mode. Accordingly, it is possible to operate the compressor32at a pressure close to the upper limit value of the discharge pressure of the compressor32. As a result, the load of the compressor32further increases and more heat can be generated by the compressor32. The heat generated by the compressor32is transferred to the primary refrigerant and then transferred to the secondary refrigerant flowing through the interior flow passage50in the condenser33. Accordingly, the temperature of the secondary refrigerant increases. The heated secondary refrigerant exchanges heat with the interior air in the vehicle interior heat exchanger20. As a result, it is possible to further improve the heating performance of the vehicular refrigeration cycle unit1.

Additionally, according to the above-described configuration, it is possible to adjust the temperature of the primary refrigerant flowing through the evaporator35in the refrigeration cycle30by adjusting the flow rate of the secondary refrigerant flowing into the evaporator35using the first flow rate adjustment unit42. Accordingly, since the pressure and density of the primary refrigerant change to desired values, it is possible to precisely adjust the load (work amount) of the compressor32. That is, it is possible to precisely control the amount of heat transferred from the compressor32to the primary refrigerant. As a result, it is possible to precisely control the temperature of the secondary refrigerant during the heating operation.

Particularly, according to the above-described configuration, the control unit90appropriately adjusts the flow state of the first flow rate adjustment unit42based on the physical quantity related to the pressure of the secondary refrigerant on the downstream side of the evaporator35. Accordingly, the ratio of the flow rates of the secondary refrigerants flowing into the evaporator35and the first bypass flow passage41changes autonomously. Thus, it is possible to more precisely control the amount of heat transferred from the compressor32to the primary refrigerant.

Additionally, when starting the heater mode, the second flow rate adjustment unit52is controlled so that the secondary refrigerant flows not to the condenser33but to the second bypass flow passage51contrary to the above description. Accordingly, the pressure of the primary refrigerant flowing through the condenser33in the refrigeration cycle30increases. Then, when shifting to the above-described stationary operation, the second flow rate adjustment unit52is controlled so that the flow rate of the secondary refrigerant flowing into the condenser33gradually increases.

By performing the above-described control, it is possible to control the pressure and temperature of the primary refrigerant flowing through the condenser33in the refrigeration cycle30. Particularly, at startup, the amount of the secondary refrigerant flowing through the condenser33is minimized and the main flow is allowed to flow through the second bypass flow passage51. Accordingly, the flow amount of the low-temperature secondary refrigerant flowing from the exterior flow passage40toward the interior flow passage50to flow into the condenser33is reduced. As a result, the pressure and temperature of the primary refrigerant in the refrigeration cycle30increase quickly. Thus, since the temperature of the secondary refrigerant exchanging heat with the primary refrigerant also increases quickly, it is possible to quickly heat the temperature of the interior air during the heating operation.

Furthermore, according to the above-described configuration, since the flow rate adjustment valve70is used as the first flow rate adjustment unit42and the second flow rate adjustment unit52, it is possible to suppress an increase in the number of parts and avoid complicating the configuration. As a result, it is possible to more easily perform manufacturing and maintenance of the vehicular refrigeration cycle unit1at a lower cost.

As described above, the first embodiment of the present disclosure has been described. Additionally, various changes and modifications can be made to each of the above configurations without departing from the gist of the present disclosure. For example, in the above-described first embodiment, an example has been described in which the secondary refrigerant does not flow into the vehicle exterior heat exchanger10at all by switching the first switching valve45in the heater mode. However, the first switching valve45may be controlled so that a small flow rate of the secondary refrigerant flows through the vehicle exterior heat exchanger10depending on the outside air temperature or operation state.

Second Embodiment

Next, a second embodiment of the present disclosure will be described with reference toFIG.6. Additionally, the same configurations as those of the first embodiment are denoted by the same reference numerals and detailed descriptions are omitted. In a vehicular refrigeration cycle unit101according to this embodiment, the configurations of a first flow rate adjustment unit142and a second flow rate adjustment unit152are different from those of the first embodiment.

Specifically, in this embodiment, the first flow rate adjustment unit142and the second flow rate adjustment unit152are configured by on-off valves80and81instead of the flow rate adjustment valve70. These on-off valves80and81are respectively provided on the first bypass flow passage41and the second bypass flow passage51. The on-off valves80and81are electrically connected to the above-described control unit90and the opening and closing state is switched by the electric signal sent from the control unit90.

Furthermore, the confluence of the first bypass flow passage41and the exterior flow passage40is located on the downstream side of the first pump43. Similarly, the confluence of the second bypass flow passage51and the interior flow passage50is located on the downstream side of the second pump53.

The first pump43and the second pump53have variable rotation speeds and can change the discharge flow rate. The first pump43and the second pump53are electrically connected to the control unit90and the discharge flow rate is controlled by the electric signal sent from a drive unit94of the control unit90. The first pump43constitutes part of the first flow rate adjustment unit142and the second pump53constitutes part of the second flow rate adjustment unit152.

FIG.6shows a state in which the vehicular refrigeration cycle unit101is operated in the heater mode. In the heater mode, the on-off valve80which is part of the first flow rate adjustment unit142is kept open. By changing the discharge flow rate of the first pump43which is a part of the first flow rate adjustment unit142in this state, the ratio of the flow rate of the secondary refrigerant flowing into the evaporator35and the flow rate of the secondary refrigerant flowing into the first bypass flow passage41is adjusted.

Operation and Effect

According to the above-described configuration, in addition to the operation and effect described in the first embodiment, since the on-off valves80and81are used instead of the flow rate adjustment valve70, it is possible to reduce the costs required for manufacturing and maintenance of the device. Further, since the flow rate of the secondary refrigerant is controlled by controlling the discharge flow rates of the first pump43and the second pump53, it is possible to more precisely adjust the temperature of the secondary refrigerant compared to a condition where the same flow rate control is performed using the flow rate adjustment valve70.

As described above, the second embodiment of the present disclosure has been described. Additionally, various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

Third Embodiment

Next, a third embodiment of the present disclosure will be described with reference toFIGS.7to10. Additionally, the same configurations as those of the above-described embodiments are denoted by the same reference numerals and detailed descriptions are omitted.

In this embodiment, various controls and configurations for accelerating the startup of the heater mode will be described. A vehicular refrigeration cycle unit201according to this embodiment further includes a first temperature measurement unit47, a second temperature measurement unit48, a third temperature measurement unit49, and a pressure measurement unit83in addition to each configuration described in the second embodiment. The first temperature measurement unit47measures the temperature of the secondary refrigerant on the downstream side of the confluence between the first bypass flow passage41and the exterior flow passage40. The second temperature measurement unit48measures the temperature of the primary refrigerant at the inlet of the compressor32. The third temperature measurement unit49measures the temperature of the secondary refrigerant on the downstream side of the confluence between the interior flow passage50and the second bypass flow passage51. The first temperature measurement unit47, the second temperature measurement unit48, and the third temperature measurement unit49are temperature sensors or thermometers. Additionally, the first temperature measurement unit47, the second temperature measurement unit48, and the third temperature measurement unit49are not shown inFIG.7. The pressure measurement unit83measures the pressure (high pressure side pressure) of the primary refrigerant on the downstream side of the compressor32. The pressure measurement unit83is a pressure sensor or pressure gauge. Further, in this embodiment, a blower21provided alongside the vehicle interior heat exchanger20is shown.

First Control when Starting Heater Mode

In a condition where the pressure (high pressure side pressure) of the primary refrigerant measured by the pressure measurement unit83is lower than a predetermined threshold value when starting the heater mode, the flow rate of the secondary refrigerant flowing into the condenser33is decreased as shown inFIG.7.

The above-described control is realized by steps S21to S24in the control flow shown inFIG.10. In step S21, it is determined whether or not the pressure of the primary refrigerant measured by the pressure measurement unit83is higher than the threshold value. When it is determined that the pressure is higher than the threshold value (step S21: Yes), the condenser flow rate is increased in step S22. When the determination in step S21is No, it is determined whether or not the pressure of the primary refrigerant measured by the pressure measurement unit83is lower than the threshold value in step S23. When the determination in step S23is Yes, the condenser flow rate is decreased in step S24.

Since the flow of the secondary refrigerant to the condenser33when starting the vehicular refrigeration cycle unit201is reduced in this way, the temperature of the primary refrigerant is increased for a temperature difference with the secondary refrigerant to radiate heat from the primary refrigerant in the condenser33. As a result, the pressure and temperature of the primary refrigerant increase quickly. Accordingly, it is possible to quickly heat the interior air.

Second Control when Starting Heater Mode

In addition to the above, as shown inFIG.9, in a condition where the temperature T1of the secondary refrigerant measured by the first temperature measurement unit47is higher than the outside air temperature when starting the heater mode, the control unit90switches the flow state of the first switching valve45so that the secondary refrigerant flows into the exterior connection flow passage44. On the other hand, in another condition where the temperature of the secondary refrigerant measured by the first temperature measurement unit47is lower than the outside air temperature, the control unit switches the flow state of the first switching valve45so that the secondary refrigerant flows into the vehicle exterior heat exchanger10.

The above-described control is realized by steps S51to S53in the control flow shown inFIG.10. In step S51, it is determined whether or not the temperature T1of the secondary refrigerant measured by the first temperature measurement unit47is lower than the outside air temperature. When the determination in step S51is Yes, the flow state of the first switching valve45is switched so that the secondary refrigerant flows into the vehicle exterior heat exchanger10in step S52. On the other hand, when the determination in step S51is No, the flow state of the first switching valve45is switched so that the secondary refrigerant flows into the exterior connection flow passage44with bypassing the vehicle exterior heat exchanger10in step S53.

Here, since the heating performance decreases in the condition where the heat amount of the secondary refrigerant decreases, the secondary refrigerant bypasses the vehicle exterior heat exchanger10using the exterior connection flow passage44when the temperature of the secondary refrigerant is higher than the outside air temperature. Accordingly, it is possible to prevent a decrease in the heat amount of the secondary refrigerant and to prevent a decrease in the pressure (low pressure side pressure) of the primary medium on the side of the evaporator35. Thus, it is possible to quickly obtain a heating effect when starting the vehicular refrigeration cycle unit1.

Third Control when Starting Heater Mode

As another control for accelerating the startup of the heater mode, as shown inFIG.8, the control unit90increases the flow rate of the secondary refrigerant flowing into the evaporator in a condition where the temperature T2of the primary refrigerant at the inlet of the compressor32measured by the second temperature measurement unit48is lower than a predetermined first threshold value when starting the vehicular refrigeration cycle unit1.

The above-described control is realized by steps S31to S34in the control flow shown inFIG.10. In step S31, it is determined whether or not the temperature of the primary refrigerant measured by the second temperature measurement unit48is higher than the first threshold value. When it is determined that the temperature is higher than the first threshold value (step S31: Yes), the evaporator flow rate is decreased in step S32. On the other hand, when the determination in step S31is No, it is determined whether or not the temperature of the primary refrigerant measured by the second temperature measurement unit48is lower than the threshold value in step S33. When the determination in step S33is Yes, the evaporator flow rate is increased in step S34.

According to the above-described configuration, it is possible to control the pressure and temperature of the primary refrigerant flowing through the evaporator35by adjusting the amount of the secondary refrigerant flowing into the evaporator35. In particular, the pressure and temperature of the primary refrigerant increase quickly by allowing the secondary refrigerant to flow through the evaporator35at startup. Accordingly, it is possible to quickly heat the interior air.

Specifically, when the flow rate of the secondary refrigerant flowing out from the condenser33and flowing through the evaporator35increases, the amount of heat absorbed from the secondary refrigerant to the primary refrigerant increases and the low pressure side pressure of the primary refrigerant increases. When the low pressure side pressure of the primary refrigerant increases, the temperature of the primary refrigerant at the inlet of the compressor32increases and hence the refrigerant density of the primary refrigerant at the inlet of the compressor32also increases. Therefore, even when the rotation speed of the compressor is the same, the circulation amount of the primary refrigerant increases and hence the power of the compressor32increases. Since the power of the compressor32increases, the high pressure side pressure of the primary refrigerant also increases due to the heat generated in the compressor32. Then, the temperature of the secondary refrigerant in the condenser33also increases and the temperature of the secondary refrigerant flowing out from the condenser33and supplied to the vehicle interior heat exchanger20also increases. As a result, it is possible to more quickly increase the temperature of the air supplied into the vehicle interior.

Fourth Control when Starting Heater Mode

Furthermore, as shown inFIG.9, in a condition where the temperature T3of the secondary refrigerant measured by the third temperature measurement unit49is lower than a predetermined second threshold value when starting the heater mode, the control unit90switches the flow state of the second switching valve55so that the secondary refrigerant flows into the interior connection flow passage54. On the other hand, in another condition where the temperature T3of the secondary refrigerant measured by the third temperature measurement unit49is higher than the predetermined second threshold value, the control unit switches the flow state of the second switching valve55so that the secondary refrigerant flows into the vehicle interior heat exchanger20.

Furthermore, when the temperature T3of the secondary refrigerant measured by the third temperature measurement unit49is lower than a predetermined third threshold value when starting the heater mode, the control unit90stops the blower21. That is, when the temperature of the secondary refrigerant is lower than the third threshold value, the supply of warm air to the vehicle interior is stopped. On the other hand, when the temperature of the secondary refrigerant increases and becomes higher than the third threshold value, the blower21is driven to start the supply of warm air to the vehicle interior.

The above-described control is realized by steps S41to S46in the control flow shown inFIG.10. In step S41, it is determined whether or not the temperature T3of the secondary refrigerant measured by the third temperature measurement unit49is lower than the predetermined second threshold value. When the determination in step S41is Yes, the process proceeds to step S42. In step S42, the flow state of the second switching valve55is switched so that the secondary refrigerant flows into the interior connection flow passage54with bypassing the vehicle interior heat exchanger20. On the other hand, when the determination in step S41is No, the flow state of the second switching valve55is switched so that the secondary refrigerant flows into the vehicle interior heat exchanger20in step S43. Further, in step S44, it is determined whether or not the temperature T3of the secondary refrigerant measured by the third temperature measurement unit49is lower than the predetermined third threshold value. When the determination in step S44is Yes, the driving of the blower21is stopped in step S45. On the other hand, when the determination in step S44is No, the blower21is driven in step S46.

According to the above-described configuration, in the condition where the temperature of the secondary refrigerant on the downstream side of the confluence between the interior flow passage50and the second bypass flow passage51is lower than the second threshold value when starting the vehicular refrigeration cycle unit1, the second switching valve55is switched so that the secondary refrigerant is not supplied to the vehicle interior heat exchanger20and flows into the interior connection flow passage54. Accordingly, the amount of the secondary refrigerant to be heated by the condenser33can be reduced. As the heat capacity of the secondary refrigerant decreases, the temperature increases faster and hence the temperature of the secondary refrigerant increases faster. Thus, it is possible to quickly obtain a heating effect when starting the vehicular refrigeration cycle unit1.

Furthermore, according to the above-described configuration, the supply of air to the vehicle interior heat exchanger20using the blower21stops until the temperature of the secondary refrigerant on the downstream side of the confluence between the interior flow passage50and the second bypass flow passage51reaches the third threshold value. Accordingly, the heat exchange between the secondary refrigerant and air in the vehicle interior heat exchanger20is suppressed. As a result, the temperature of the secondary refrigerant increases quickly. Thus, it is possible to shorten the time until the temperature of the air finally supplied into the vehicle interior from the vehicle interior heat exchanger20reaches the set temperature.

As described above, the embodiments of the present disclosure have been described. Additionally, various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure. For example, the process flow of the control unit90in each of the above-described embodiments may be performed by changing the process order in an appropriate process range.

Further, the “exterior flow passage40” and the “interior flow passage50” do not necessarily mean that they are provided only outside the vehicle interior or only inside the vehicle interior. That is, part of the exterior flow passage40may be provided inside the vehicle interior when necessary and a part of the interior flow passage50may be provided outside the vehicle interior.

Furthermore, all of the four control flows described in the third embodiment may be implemented in the control unit90and all of them may be performed simultaneously or only four or less appropriately selected control flows may be implemented and performed.

APPENDIX

The vehicular refrigeration cycle unit1described in each embodiment is understood, for example, as below.

(1) The vehicular refrigeration cycle unit1according to a first aspect is the vehicular refrigeration cycle unit1which is installed between the vehicle exterior heat exchanger10and the vehicle interior heat exchanger20and exchanging heat between the secondary refrigerants respectively flowing through the vehicle exterior heat exchanger10and the vehicle interior heat exchanger20, the vehicular refrigeration cycle unit including: the refrigeration cycle30including the compressor32, the condenser33, the expansion valve34, and the evaporator35through which the primary refrigerant sequentially flows; the exterior flow passage40through which the secondary refrigerant is circulated between the evaporator35and the vehicle exterior heat exchanger10; the interior flow passage50through which the secondary refrigerant is circulated between the condenser33and the vehicle interior heat exchanger20; the pair of flow passage switching valves60connecting the exterior flow passage40and the interior flow passage50to allow to switch the flow state of the secondary refrigerant; the first bypass flow passage41which is installed aside the exterior flow passage40and with bypassing the evaporator35; and the first flow rate adjustment unit42adjusting the flow rate of the secondary refrigerant flowing into the first bypass flow passage41and the evaporator35, wherein the first flow rate adjustment unit42is the flow passage switching valve distributing the secondary refrigerant flowing from one flow passage into two flow passage and is allowed to change the ratio of the flow rate of the secondary refrigerant between these two flow passages.

According to the above-described configuration, it is possible to precisely adjust the load of the compressor32by adjusting the amount of the secondary refrigerant flowing into the evaporator35using the first flow rate adjustment unit42. Accordingly, it is possible to precisely control the amount of heat transferred from the compressor32to the primary refrigerant.

(2) The vehicular refrigeration cycle unit1according to a second aspect is the vehicular refrigeration cycle unit1of (1), wherein the first flow rate adjustment unit42includes the on-off valve80installed in the first bypass flow passage41and the first pump43installed in the exterior flow passage40.

According to the above-described configuration, it is possible to configure the device at a low cost by configuring the first flow rate adjustment unit42only with the on-off valve80and the first pump43.

(3) The vehicular refrigeration cycle unit1according to a third aspect is the vehicular refrigeration cycle unit1of (1) or (2) further including: the control unit90switching the states of the pair of flow passage switching valves60and the first flow rate adjustment unit42, wherein the flow states of the flow passage switching valves60are switched by the control unit90so that the secondary refrigerant, which has flowed out from the vehicle interior heat exchanger20via the interior flow passage50, is flowed into at least one of the evaporator35and the first bypass flow passage41via the exterior flow passage40.

According to the above-described configuration, the high-temperature secondary refrigerant flowing out from the vehicle interior heat exchanger20flows into the evaporator35. Accordingly, the temperature and density of the primary refrigerant heading to the compressor32from the evaporator35increase. As a result, the load of the compressor32increases and hence the amount of heat transferred from the compressor32to the primary refrigerant can be increased.

(4) The vehicular refrigeration cycle unit1according to a fourth aspect is the vehicular refrigeration cycle unit1of (3) further including: the measurement unit46measuring the physical quantity related to the pressure of the primary refrigerant on the downstream side of the evaporator35in the refrigeration cycle30, wherein the flow state of the first flow rate adjustment unit42is adjusted by the control unit90based on the measurement result of the measurement unit46.

According to the above-described configuration, since the flow state of the first flow rate adjustment unit42is adjusted based on the physical quantity related to the pressure of the primary refrigerant on the downstream side of the evaporator35, the ratio of the flow rate of the secondary refrigerant flowing into the evaporator35and the first bypass flow passage41changes. Accordingly, it is possible to more precisely control the amount of heat transferred from the compressor32to the primary refrigerant.

(5) The vehicular refrigeration cycle unit1according to a fifth aspect is the vehicular refrigeration cycle unit1of any one aspect of (1) to (4) further including: the second bypass flow passage51which is installed aside the interior flow passage50with bypassing the condenser33; and the second flow rate adjustment unit52adjusting the flow rate of the secondary refrigerant flowing into the second bypass flow passage51and the condenser33.

According to the above-described configuration, it is possible to control the pressure and temperature of the primary refrigerant flowing through the condenser33by adjusting the amount of the secondary refrigerant flowing into the condenser33using the second flow rate adjustment unit52.

(6) The vehicular refrigeration cycle unit1according to a sixth aspect is the vehicular refrigeration cycle unit1of (5), wherein the second flow rate adjustment unit52is the flow passage switching valve distributing the secondary refrigerant flowing from one flow passage into two flow passages and is allowed to change the ratio of the flow rate of the secondary refrigerant between these two flow passages.

According to the above-described configuration, it is possible to more easily perform the manufacturing or maintenance of the device by using the flow rate adjustment valve.

(7) The vehicular refrigeration cycle unit1according to a seventh aspect is the vehicular refrigeration cycle unit1of (5), wherein the second flow rate adjustment unit52includes the on-off valve81installed in the second bypass flow passage51and the second pump53installed in the interior flow passage50.

According to the above-described configuration, it is possible to configure the device at a low cost by configuring the second flow rate adjustment unit52only with the on-off valve81and the second pump53.

(8) The vehicular refrigeration cycle unit1according to an eighth aspect is the vehicular refrigeration cycle unit1of any one aspect of (5) to (7) further including: the control unit90switching the states of the pair of flow passage switching valves60and the second flow rate adjustment unit52, wherein, when starting the vehicular refrigeration cycle unit1, the flow states of the flow passage switching valves60and the second flow rate adjustment unit52are switched by the control unit90so that the secondary refrigerant passing through the exterior flow passage40flows into the second bypass flow passage51via the interior flow passage50, and wherein, during a stationary operation of the vehicular refrigeration cycle unit1, the flow state of the second flow rate adjustment unit52is switched by the control unit90so that the secondary refrigerant flows into the condenser33.

According to the above-described configuration, it is possible to control the pressure and temperature of the primary refrigerant flowing through the condenser33by adjusting the amount of the secondary refrigerant flowing through the condenser33using the second flow rate adjustment unit52. Particularly, at startup, since the secondary refrigerant does not flow through the condenser33, the pressure and temperature of the primary refrigerant increase quickly. Accordingly, it is possible to quickly heat the interior air.

(9) The vehicular refrigeration cycle unit1according to a ninth aspect is the vehicular refrigeration cycle unit1of (3) or (4), wherein, when starting the vehicular refrigeration cycle unit1, the flow states of the flow passage switching valves60and the first flow rate adjustment unit42are switched by the control unit90so that the secondary refrigerant passing through the interior flow passage50flows into the evaporator35through the exterior flow passage40, and wherein, during a stationary operation of the vehicular refrigeration cycle unit1, the flow state of the first flow rate adjustment unit42is switched by the control unit90so that the secondary refrigerant flows into the first bypass flow passage41.

According to the above-described configuration, it is possible to control the pressure and temperature of the primary refrigerant flowing through the evaporator35by adjusting the amount of the secondary refrigerant flowing into the evaporator35using the first flow rate adjustment unit42. Particularly, at startup, since the secondary refrigerant flows through the evaporator35, the pressure and temperature of the primary refrigerant increase quickly. Accordingly, it is possible to quickly heat the interior air.

(10) The vehicular refrigeration cycle unit1according to a tenth aspect is the vehicular refrigeration cycle unit1of (9) further including: the exterior connection flow passage44which is installed aside the exterior flow passage40with bypassing the vehicle exterior heat exchanger10; the first switching valve45switching the flow state of the exterior connection flow passage44; and the first temperature measurement unit47measuring the temperature of the secondary refrigerant on the downstream side of the confluence between the first bypass flow passage41and the exterior flow passage40, wherein, when starting the vehicular refrigeration cycle unit1, the flow state of the first switching valve45is switched by the control unit90so that the secondary refrigerant flows into the exterior connection flow passage44in a condition where the temperature of the secondary refrigerant measured by the first temperature measurement unit47is higher than the outside air temperature, and the flow state of the first switching valve45is switched by the control unit90so that the secondary refrigerant flows into the vehicle exterior heat exchanger10in another condition where the temperature of the secondary refrigerant measured by the first temperature measurement unit47is lower than the outside air temperature.

Since the heating performance decreases when the heat amount of the secondary refrigerant decreases, the secondary refrigerant bypasses the vehicle exterior heat exchanger10using the exterior connection flow passage44when the temperature of the secondary refrigerant is higher than the outside air temperature. Accordingly, it is possible to prevent a decrease in the heat amount of the secondary refrigerant and to prevent a decrease in the pressure (low pressure side pressure) of the primary refrigerant on the side of the evaporator35. Thus, it is possible to quickly obtain a heating effect when starting the vehicular refrigeration cycle unit1.

(11) The vehicular refrigeration cycle unit1according to an eleventh aspect is the vehicular refrigeration cycle unit1of (9) or (10) further including: the interior connection flow passage54which is installed aside the interior flow passage50and with bypassing the vehicle interior heat exchanger20; the second switching valve55switching the flow state of the interior connection flow passage54; and the second temperature measurement unit48measuring the temperature of the primary refrigerant at the inlet of the compressor32of the refrigeration cycle30, wherein, when starting the vehicular refrigeration cycle unit1, the flow state of the second switching valve55is switched by the control unit90so that the secondary refrigerant flows into the interior connection flow passage54in a condition where the temperature of the primary refrigerant measured by the second temperature measurement unit48is lower than the predetermined first threshold value, and the flow state of the second switching valve55is switched by the control unit90so that the secondary refrigerant flows into the vehicle interior heat exchanger20in another condition where the temperature of the primary refrigerant measured by the second temperature measurement unit48is higher than the first threshold value.

According to the above-described configuration, the amount of the secondary refrigerant to be heated by the condenser33can be reduced. As the heat capacity of the secondary refrigerant decreases, the temperature increases faster and hence the temperature of the secondary refrigerant increases faster. Thus, it is possible to quickly obtain a heating effect when starting the vehicular refrigeration cycle unit1.

(12) The vehicular refrigeration cycle unit1according to a twelfth aspect is the vehicular refrigeration cycle unit1of (8) further including: the blower21which is installed aside the vehicle interior heat exchanger20and supplying air exchanging heat in the vehicle interior heat exchanger20into the vehicle interior; and the third temperature measurement unit49measuring the temperature of the secondary refrigerant on the downstream side of the confluence between the interior flow passage50and the second bypass flow passage51, wherein, when starting the vehicular refrigeration cycle unit1, the blower21is stopped by the control unit90in a condition where the temperature of the secondary refrigerant measured by the third temperature measurement unit49is lower than the predetermined second threshold value, and the blower21is driven by the control unit90in another condition where the temperature of the secondary refrigerant measured by the third temperature measurement unit49is higher than the second threshold value.

According to the above-described configuration, the supply of air to the vehicle interior heat exchanger20using the blower21stops until the temperature of the secondary refrigerant on the downstream side of the confluence between the interior flow passage50and the second bypass flow passage51reaches the second threshold value. Accordingly, it is possible to more quickly increase the temperature of the air supplied from the vehicle interior heat exchanger20into the vehicle interior.

INDUSTRIAL APPLICABILITY

In the vehicular refrigeration cycle unit, it is possible to more precisely adjust the temperature of the secondary refrigerant.

REFERENCE SIGNS LIST