Vehicular air conditioner

Abstract

[Problem] To suppress frost formation or to remove frost without stopping heating in a vehicular air conditioner. [Solution] A vehicular air conditioner 1 comprises: a refrigerant circuit 10 including a compressor 11 that compresses a refrigerant, an indoor condenser 12 configured such that the refrigerant flows therethrough to heat air for heating a cabin interior, a bypass channel 231 configured to carry a flow of the refrigerant while bypassing the indoor condenser 12, and an outdoor heat exchanger 14 configured such that the refrigerant flows therethrough to exchange heat with air outside the cabin; and a control device 80 configured to control the operation of the refrigerant circuit 10. The control device 80 is configured to cause, when it is determined that there is a possibility of frost formation in the outdoor heat exchanger 14, execution of a heating and defrosting operation to direct a flow of the refrigerant that has been compressed by the compressor 11 to the bypass channel 231 and the indoor condenser 12, and to use the indoor condenser 12 to perform heating while also defrosting the outdoor heat exchanger 14.

Description

Vehicle air conditioning system

[0001] The present invention relates to an air conditioning system for a vehicle.

[0002] Systems equipped with a refrigerant circuit that functions as a heat pump for air conditioning a vehicle and regulating the temperature of onboard equipment are known. In such systems, the exterior heat exchanger generally functions as a heat absorber during heating operation. When the outside air temperature is low, condensed water may freeze on the surface of the exterior heat exchanger, causing frost to form. When frost forms on the exterior heat exchanger, the exterior heat exchanger may not be able to absorb enough heat, which may result in insufficient heating of the vehicle interior. In such cases, a defrosting operation is required to remove the frost. For example, Patent Document 1 discloses several methods for performing a defrosting operation while stopping the heating of the vehicle interior.

[0003] Japanese Patent Application Laid-Open No. 2022-148724

[0004] An object of the present invention is to provide a vehicle air conditioner that can suppress frost formation or perform defrosting without stopping heating.

[0005] According to one aspect of the present invention, a vehicle air conditioning system includes a refrigerant circuit including a compressor that compresses a refrigerant, an interior condenser configured to heat air for heating the interior of a vehicle cabin through which the refrigerant flows, a bypass flow path configured to cause the refrigerant to flow bypassing the interior condenser, and an exterior heat exchanger configured to exchange heat with air outside the vehicle cabin through which the refrigerant flows, and a control device configured to control the operation of the refrigerant circuit, wherein the control device is configured to, when it is determined that frost is likely to form on the exterior heat exchanger or that frost has formed, cause the refrigerant compressed by the compressor to flow through the bypass flow path and the interior condenser, and to perform heating and defrosting operation in which the interior condenser is used to perform the heating and defrost the exterior heat exchanger.

[0006] According to the present invention, it is possible to provide a vehicle air conditioner that can suppress frost formation or perform defrosting without stopping heating.

[0007] Fig. 1 is an explanatory diagram showing an outline of a configuration example of a vehicle air conditioner according to one embodiment, and is an explanatory diagram relating to an outside-air heat absorption heating operation. Fig. 2 is a flowchart showing an outline of an operation example relating to a heating operation of a vehicle air conditioner in an environment where frost formation may occur. Fig. 3 is an explanatory diagram showing an outline of a configuration example of a vehicle air conditioner according to one embodiment, and is an explanatory diagram relating to an exhaust heat recovery heating defrosting operation. Fig. 4 is an explanatory diagram showing an outline of a configuration example of a vehicle air conditioner according to one embodiment, and is an explanatory diagram relating to an exhaust heat recovery heating defrosting operation in a defrost priority mode.

[0008] [Configuration of a Vehicle Air Conditioner] One embodiment will be described with reference to the drawings. This embodiment relates to a vehicle air conditioner having a refrigerant circuit. The vehicle air conditioner of this embodiment is mounted on a vehicle such as an electric vehicle. The vehicle air conditioner has a function of regulating the temperature, humidity, etc. of the air inside the vehicle cabin. The vehicle air conditioner is configured to not only regulate the temperature inside the vehicle cabin, but also regulate the temperatures of on-board equipment such as a motor and a battery mounted on the vehicle.

[0009] FIG. 1 is an explanatory diagram showing an outline of an example configuration of a vehicle air conditioner 1 according to this embodiment. The vehicle air conditioner 1 includes a refrigerant circuit 10 configured to circulate a refrigerant. The refrigerant may be, but is not limited to, R744 (carbon dioxide) refrigerant, for example. The vehicle air conditioner 1 also includes a heat medium circuit 40 configured to circulate a heat medium fluid, such as a coolant liquid. The heat medium circuit 40 may include, for example, a battery temperature control circuit or a motor temperature control circuit that regulates the temperatures of a battery and a motor.

[0010] The automotive air conditioner 1 also includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 60, which is an air conditioning unit. The automotive air conditioner 1 also includes a control device 80 that controls the operation of various sensors and each part of the automotive air conditioner 1. The operation of the automotive air conditioner 1 is controlled by the control device 80 based on the detection values ​​of the various sensors, various requests, etc.

[0011] The control device 80 may include various integrated circuits for calculation, storage, and other functions. The operation of the control device 80 may be performed according to a program stored in the various integrated circuits as hardware or software.

[0012] The refrigerant circuit 10 includes a compressor 11, a high-temperature side heat exchanger, a pressure reducing device, a low-temperature side heat exchanger, and an accumulator 17, which are arranged so that a refrigerant circulates. The refrigerant circuit 10 is configured to function as a heat pump. That is, in the refrigerant circuit 10, the refrigerant is compressed into a high-temperature, high-pressure gas by the compressor 11, condenses into a high-temperature, high-pressure liquid by releasing heat in the high-temperature side heat exchanger, expands into a low-pressure gas-liquid two-phase state by the pressure reducing device, absorbs heat in the low-temperature side heat exchanger, evaporates into a low-temperature, low-pressure gas, and is sent back to the compressor 11 via the accumulator 17. The accumulator 17 is not limited to this, but in this embodiment, an accumulator with a built-in heat exchanger is used.

[0013] The refrigerant circuit 10 includes an interior condenser 12. The interior condenser 12 is housed in a case 61 of the HVAC unit 60. The interior condenser 12 is configured to function as a high-temperature side heat exchanger during heating operation, for example, and heat the air supplied to the vehicle cabin. The refrigerant circuit 10 also includes multiple expansion valves and heat exchangers. That is, the refrigerant circuit 10 includes a first expansion valve 131 and an exterior heat exchanger 14, a second expansion valve 132 and an interior evaporator 15, and a third expansion valve 133 and an evaporator 161 of a chiller 16, which serve as a pressure reducing device and a low-temperature side heat exchanger. The interior evaporator 15 is housed in the case 61 of the HVAC unit 60. The interior evaporator 15 is configured to function as a low-temperature side heat exchanger during cooling operation, for example, and cool the air supplied to the vehicle cabin. The chiller 16 is configured to allow the refrigerant to exchange heat with the heat medium flowing through the heat medium circuit 40. The exterior heat exchanger 14 is configured to allow the refrigerant to exchange heat with the air outside the vehicle cabin. The exterior heat exchanger 14 functions as an evaporator during heating operation, for example, and as a condenser during cooling operation, for example.

[0014] The refrigerant circuit 10 also includes multiple solenoid valves for switching between the various circuits. In the vehicle air conditioner 1 of this embodiment, a first branch portion 211 is provided downstream of the outlet of the compressor 11. The vehicle air conditioner 1 also includes, downstream of the first branch portion 211, a flow path through which the refrigerant discharged from the compressor 11 flows to the interior condenser 12, and a bypass flow path 231 that bypasses the interior condenser 12. These flow paths merge at a first junction 221. The flow path through which the refrigerant flows to the interior condenser 12 includes a first solenoid valve 181 and a first check valve 191. The bypass flow path 231 includes a second solenoid valve 182. When both the first solenoid valve 181 and the second solenoid valve 182 are opened, the flow rate of the bypass flow path 231 is generally greater than that of the interior condenser 12. The first solenoid valve 181 or the second solenoid valve 182 may be a valve capable of controlling the flow rate, thereby adjusting the ratio of the refrigerant flowing to the indoor condenser 12 and the bypass flow path 231. Furthermore, instead of providing the first solenoid valve 181 and the second solenoid valve 182, a proportional control three-way valve may be provided in the first branching section 211, and this proportional control three-way valve may be used to adjust the ratio of the refrigerant flowing to the indoor condenser 12 and the bypass flow path 231. In this case, the functions of the first solenoid valve 181 and the second solenoid valve 182 are performed by the proportional control three-way valve.

[0015] The refrigerant circuit 10 also includes a third solenoid valve 183 for controlling the flow of refrigerant that bypasses the first expansion valve 131 and the outdoor heat exchanger 14. The refrigerant circuit 10 also includes a fourth solenoid valve 184 for controlling the flow of refrigerant from the outdoor heat exchanger 14 returning to the compressor 11 via the accumulator 17. The refrigerant circuit 10 also includes a plurality of check valves, namely a second check valve 192 and a third check valve 193, for rectifying the flow in the various circuits described above. The refrigerant flow path is switched by opening and closing the various valves, and the operating mode, such as heating, cooling, and temperature control of various devices, is switched.

[0016] The heat medium circuit 40 may include, for example, an on-board equipment heat exchanger 41 provided for adjusting the temperature of on-board equipment such as a battery or a motor, a chiller pump 42 for circulating the heat medium within the heat medium circuit 40, a heat medium heating device 43 configured to heat the heat medium, and a heat exchanger 44 of the chiller 16 for exchanging heat with the refrigerant in the refrigerant circuit 10.

[0017] The HVAC unit 60 includes a case 61 that forms the outer shell of the HVAC unit 60 and defines an air flow passage 62 therein. The HVAC unit 60 includes an intake unit 63 that takes in outside air or inside air, and a blower 64 that supplies the air taken in through the intake unit 63 to the air flow passage 62 within the case 61. An interior evaporator 15 is installed upstream of the air flow passage 62. An interior condenser passage and a bypass passage are formed in parallel downstream of the air flow passage 62. The interior condenser 12 is installed in the interior condenser passage. The flow of air into the interior condenser passage or the bypass passage is adjusted by an air mix damper 65. With this configuration, air that has been heated or cooled through the interior condenser 12 or the interior evaporator 15 is sent into the vehicle cabin.

[0018] [Operation of Vehicle Air Conditioner] The vehicle air conditioner 1 of this embodiment has an air conditioning function of adjusting the temperature, humidity, etc. of the air inside the vehicle cabin, such as heating or cooling the vehicle cabin. The control device 80 of the vehicle air conditioner 1 controls the opening and closing of each expansion valve and solenoid valve to switch the refrigerant flow path depending on the operation mode. The control device 80 also controls the rotation speed, etc. of the compressor 11. The control device 80 also controls the rotation speed, etc. of a fan (not shown) of the exterior heat exchanger 14. The control device 80 also controls the operation of the intake unit 63, blower 64, air mix damper 65, etc. of the HVAC unit 60.

[0019] Generally, during heating operation in winter, when the outdoor temperature is low, such as around 0°C, and the humidity is relatively high, frost may form on the exterior heat exchanger 14. When frost forms, the amount of heat absorbed by the exterior heat exchanger 14 decreases. To maintain heating capacity, this frost must be removed. The vehicle air conditioning system 1 of this embodiment is particularly configured to suppress frost formation on the exterior heat exchanger 14 and perform necessary defrosting without stopping heating operation, thereby preventing a loss of comfort in the vehicle cabin.

[0020] The operation of the automotive air conditioner 1 in a heating operation in an environment where frost formation may occur will be described below. Fig. 2 is a flowchart showing an outline of an example of the operation of the control device 80 related to this operation.

[0021] In step S1, the control device 80 controls each component of the automotive air conditioner 1 to perform normal outside air heat absorption heating operation. That is, as shown in Fig. 1 , the control device 80 opens the first solenoid valve 181 and the fourth solenoid valve 184 and closes the second solenoid valve 182 and the third solenoid valve 183. The control device 80 also adjusts the opening degree of the first expansion valve 131 and closes the second expansion valve 132 and the third expansion valve 133.

[0022] As a result, the refrigerant circulates through the compressor 11, first branch portion 211, first solenoid valve 181, interior condenser 12, first check valve 191, first junction portion 221, second branch portion 212, first expansion valve 131, exterior heat exchanger 14, third branch portion 213, fourth solenoid valve 184, second junction portion 222, second check valve 192, fourth junction portion 224, accumulator 17, and compressor 11 in this order. The refrigerant dissipates heat to the air in the interior condenser 12 and absorbs heat from outside the vehicle cabin in the exterior heat exchanger 14. The air heated by the interior condenser 12 is introduced into the vehicle cabin, thereby heating the vehicle cabin.

[0023] In step S2, the control device 80 determines whether the refrigerant temperature at the outlet of the outdoor heat exchanger 14 has become lower than the outdoor air temperature by a predetermined temperature, i.e., whether the difference between the refrigerant temperature T_ohx_out at the outlet of the outdoor heat exchanger 14 and the outdoor air temperature OAT (T_ohx_out - OAT) is lower than a predetermined temperature Z. The predetermined temperature Z is, for example, a temperature at which heating capacity is not significantly reduced due to frost formation on the outdoor heat exchanger 14. While not limited to this, the predetermined temperature Z is, for example, −10°C. In this embodiment, setting the predetermined temperature Z prevents a reduction in heating capacity due to frost formation. Alternatively, the predetermined temperature Z may be, for example, a temperature at which it is determined that frost has formed on the outdoor heat exchanger 14. When the difference between the refrigerant temperature T_ohx_out at the outlet of the outdoor heat exchanger 14 and the outdoor air temperature OAT is not lower than a predetermined temperature Z, that is, when T_ohx_out - OAT < Z is not satisfied, the processing returns to step S1 and the above-mentioned normal outdoor air heat absorption heating operation continues.

[0024] In step S2, if the difference between the refrigerant temperature T_ohx_out at the outlet of the exterior heat exchanger 14 and the outdoor air temperature OAT is lower than a predetermined temperature Z, i.e., if T_ohx_out - OAT < Z is satisfied, the process proceeds to step S3. This situation indicates that frost may form on the exterior heat exchanger 14, or that frost has formed and continuing normal outdoor air heat absorption heating operation would eventually result in a significant decrease in heating capacity. Therefore, in the process from step S3 onwards, the exterior heat exchanger 14 is defrosted while continuing to heat the vehicle cabin. Here, defrosting includes removing or reducing the frost that has formed, or preventing the frost from progressing or forming.

[0025] In step S3, the control device 80 reduces the amount of air sent by the blower 64 of the HVAC unit 60. Because part of the heat of the refrigerant is used for defrosting, the amount of air sent must be reduced in order to make the temperature of the air introduced into the vehicle cabin the same as that in normal heating operation. The control device 80 controls the amount of air sent in accordance with various conditions.

[0026] In step S4, the control device 80 controls each part of the vehicle air conditioner 1 to perform the exhaust heat recovery, heating, and defrosting operation. That is, as shown in Fig. 3, the control device 80 opens the first solenoid valve 181 and closes the second solenoid valve 182, the third solenoid valve 183, and the fourth solenoid valve 184. The control device 80 also fully opens the first expansion valve 131 to prevent the refrigerant from being decompressed, closes the second expansion valve 132, and adjusts the opening degree of the third expansion valve 133. The rotation speed of the compressor 11 may be controlled to be maximum.

[0027] In step S5, the control device 80 drives the chiller pump 42 of the heat medium circuit 40. For example, in an in-vehicle equipment heat exchanger 41 provided in an in-vehicle equipment such as a motor or a battery, the heat medium flowing through the heat medium circuit 40 is heated by exhaust heat from the in-vehicle equipment.

[0028] As a result, the refrigerant circulates in the following order: compressor 11, first branch section 211, first solenoid valve 181, indoor condenser 12, first check valve 191, first junction section 221, second branch section 212, first expansion valve 131, outdoor heat exchanger 14, third branch section 213, heat exchanger of accumulator 17, third check valve 193, third junction section 223, fourth branch section 214, third expansion valve 133, evaporator 161 of chiller 16, fourth junction section 224, accumulator 17, and compressor 11.

[0029] The refrigerant releases heat in the interior condenser 12 and the exterior heat exchanger 14, and absorbs heat in the evaporator 161 of the chiller 16 from the heat medium flowing through the heat exchanger 44 of the chiller 16. The air heated in the interior condenser 12 is introduced into the vehicle cabin, thereby heating the vehicle cabin. Defrosting is also performed by heating the exterior heat exchanger 14. The exhaust heat recovery heating and defrosting operation is a heating and defrosting operation performed by high-temperature refrigerant flowing through the interior condenser 12 and the exterior heat exchanger 14. In this embodiment, the refrigerant returning to the compressor 11 is heated in the accumulator 17 with a built-in heat exchanger by the remaining heat of the refrigerant after passing through the exterior heat exchanger 14.

[0030] The chiller pump 42 circulates the heat medium through the heat medium circuit 40, and the heat medium heats the refrigerant in the refrigerant circuit 10 in the chiller 16. The heat carried by the heat medium is waste heat from the on-board equipment. In this way, the refrigerant circuit 10 operates as a heat pump by absorbing waste heat from the on-board equipment.

[0031] In step S6, the control device 80 determines whether defrosting is to be prioritized. For example, defrosting may be prioritized until it is determined that defrosting is completed for the first time after the exhaust heat recovery heating defrosting operation is started. Alternatively, defrosting may be prioritized for an initial predetermined period after the exhaust heat recovery heating defrosting operation is started. Alternatively, a period of several seconds during which defrosting is prioritized may be provided at predetermined time intervals. Alternatively, defrosting may be prioritized depending on various conditions, such as the outlet temperature T_ohx_out of the outdoor heat exchanger 14, the difference between that temperature T_ohx_out and the outdoor air temperature OAT, and the temperature of the air that has passed through the outdoor heat exchanger 14.

[0032] If it is determined in step S6 that defrosting is prioritized, the process proceeds to step S7. In step S7, the control device 80 performs the exhaust heat recovery heating defrosting operation in the defrost-priority mode. That is, as shown in FIG. 4 , the control device 80 fully opens the second solenoid valve 182. By fully opening the second solenoid valve 182, the amount of refrigerant flowing through the bypass flow path 231 and the indoor condenser 12 decreases. At this time, the amount of refrigerant flowing through the bypass flow path 231 becomes greater than the amount of refrigerant flowing through the indoor condenser 12. The ratio of refrigerant flowing through the indoor condenser 12 to that flowing through the bypass flow path 231 may be adjusted. The refrigerant flowing through the bypass flow path 231 without flowing through the indoor condenser 12 supplies more heat to the outdoor heat exchanger 14 without dissipating heat in the indoor condenser 12. Therefore, defrosting of the outdoor heat exchanger 14 is more advanced than in the case of FIG. 3 where the second solenoid valve 182 is closed. Then, the process proceeds to step S9.

[0033] If it is determined in step S6 that defrosting is not prioritized, the process proceeds to step S8. In step S8, the control device 80 performs the exhaust heat recovery heating / defrosting operation in a normal heating / defrosting mode that does not prioritize defrosting. That is, as shown in FIG. 3, the control device 80 closes the second solenoid valve 182. By closing the second solenoid valve 182, the refrigerant does not flow through the bypass flow path 231, and all of the refrigerant flows through the indoor condenser 12 and the outdoor heat exchanger 14, which are connected in series. Thereafter, the process proceeds to step S9.

[0034] From step S9 onwards, the exhaust heat recovery heating / defrosting operation is carried out in the defrost-priority mode or the normal heating / defrosting mode selected as described above.

[0035] In step S9, the control device 80 determines whether the temperature T_water_chiller_out of the heat medium at the outlet of the heat exchanger 44 of the chiller 16 of the heat medium circuit 40 is lower than a predetermined temperature W. The predetermined temperature W is a temperature related to the lower limit of the temperature suitable as the operating temperature of on-board equipment, the temperature of which is regulated by the on-board equipment heat exchanger 41, such as a motor or a battery. The predetermined temperature W is also a temperature related to the temperature required to supply the refrigerant circuit 10 with heat necessary for the exhaust heat recovery heating / defrosting operation. In other words, the control device 80 determines whether the temperature of the on-board equipment is too low, whether the amount of heat absorbed by the evaporator 161 is insufficient, etc. When the temperature T_water_chiller_out of the heat medium at the outlet of the heat exchanger 44 of the chiller 16 of the heat medium circuit 40 is lower than the predetermined temperature W, that is, when T_water_chiller_out < W is satisfied, the process proceeds to step S10.

[0036] In step S10, the control device 80 turns on the heat medium heater 43 of the heat medium circuit 40. The control device 80 also controls the output of the heat medium heater 43. The heat medium heater 43 heats the heat medium in the heat medium circuit 40. In this way, sufficient heat is supplied to the refrigerant in the refrigerant circuit 10 while maintaining the on-board equipment, such as the motor and the battery, whose temperatures are regulated by the on-board equipment heat exchanger 41, at appropriate temperatures. Then, the process proceeds to step S11.

[0037] In step S11, the control device 80 determines whether the temperature T_water_chiller_out of the heat medium at the outlet of the heat exchanger 44 of the chiller 16 has become higher than a predetermined temperature W. When the temperature T_water_chiller_out of the heat medium at the outlet of the heat exchanger 44 is not higher than the predetermined temperature W, that is, when T_water_chiller_out > W is not satisfied, the process returns to step S10 and the above-mentioned process is repeated. That is, the exhaust heat recovery heating and defrosting operation continues while the heat medium is heated using the heat medium heating device 43. On the other hand, when the temperature T_water_chiller_out of the heat medium at the outlet of the heat exchanger 44 has become higher than the predetermined temperature W, that is, when T_water_chiller_out > W is satisfied, the process proceeds to step S12.

[0038] In step S12, the control device 80 turns off the heat medium heater 43 of the heat medium circuit 40. That is, the heating of the heat medium using the heat medium heater 43 is terminated. Thereafter, the process returns to step S6. That is, the exhaust heat recovery heating defrosting operation is continued without heating the heat medium using the heat medium heater 43.

[0039] In step S9, if the temperature T_water_chiller_out of the heat medium at the outlet of the heat exchanger 44 of the heat medium circuit 40 is not lower than the predetermined temperature W, that is, if T_water_chiller_out<W is not satisfied, the process proceeds to step S13.

[0040] In step S13, the control device 80 determines whether the speed of the vehicle equipped with the automotive air conditioner 1 is faster than a predetermined speed. This predetermined speed is a speed at which the vehicle can be said to be moving slowly when it is slower than this predetermined speed. If the vehicle speed is faster than the predetermined speed, the process proceeds to step S14. At this time, because the vehicle speed is faster than the predetermined speed, the flow of outside air hits the exterior heat exchanger 14 even if the fan of the exterior heat exchanger 14 is stopped. Therefore, the temperature of the exterior heat exchanger 14 may not rise easily.

[0041] In step S14, the control device 80 determines whether the current temperature Tair_ohx_out(t) of the air passing through the outdoor heat exchanger 14 is higher than the temperature Tair_ohx_out(t-1) of the air passing through the outdoor heat exchanger 14 a predetermined time ago, and whether this temperature rise is higher than a predetermined temperature X. When the temperature of the outdoor heat exchanger 14 has risen to a certain extent, the current temperature Tair_ohx_out(t) of the air passing through the outdoor heat exchanger 14 becomes higher than the temperature Tair_ohx_out(t-1) of the air passing through the outdoor heat exchanger 14 a predetermined time ago, and this temperature rise becomes higher than the predetermined temperature X. In other words, Tair_ohx_out(t) > Tair_ohx_out(t-1) + X is satisfied. When Tair_ohx_out(t) > Tair_ohx_out(t-1) + X is not satisfied, the process returns to step S6. In other words, the exhaust heat recovery heating / defrosting operation continues.

[0042] On the other hand, when it is determined in step S14 that Tair_ohx_out(t) > Tair_ohx_out(t-1) + X is satisfied, the process proceeds to step S15. In step S15, the control device 80 determines whether it has been determined in step S14 that Tair_ohx_out(t) > Tair_ohx_out(t-1) + X is satisfied a predetermined number of times. When the determination has not been made the predetermined number of times, the process returns to step S6. That is, the exhaust heat recovery heating and defrosting operation continues. On the other hand, when the determination has been made the predetermined number of times, the process returns to step S1. That is, when the temperature of the outdoor heat exchanger 14 is continuously rising, it is determined that defrosting of the outdoor heat exchanger 14 is completed, the exhaust heat recovery heating and defrosting operation is ended, and normal outdoor air heat absorption heating operation is resumed.

[0043] If it is determined in step S13 that the vehicle speed is not faster than the predetermined speed, the process proceeds to step S16. The process proceeds to step S16 when it is determined that the vehicle is moving slowly or is stopped. At this time, the flow of outside air does not hit the exterior heat exchanger 14 very much, and the temperature of the exterior heat exchanger 14 is likely to rise.

[0044] In step S16, the control device 80 determines whether the refrigerant temperature T_ohx_out at the outlet of the outdoor heat exchanger 14 is higher than a predetermined temperature Y. The predetermined temperature Y is, for example, a temperature at which it can be determined that defrosting is complete. While not limited to this, the predetermined temperature Y is, for example, 10°C. If the refrigerant temperature T_ohx_out at the outlet of the outdoor heat exchanger 14 is not higher than the predetermined temperature Y, i.e., if T_ohx_out > Y is not satisfied, the process returns to step S6, and the above-mentioned exhaust heat recovery heating / defrosting operation is continued. If the refrigerant temperature T_ohx_out at the outlet of the outdoor heat exchanger 14 is higher than the predetermined temperature Y, i.e., if T_ohx_out > Y is satisfied, the process returns to step S1. That is, it is determined that defrosting of the outdoor heat exchanger 14 is complete, the exhaust heat recovery heating / defrosting operation is terminated, and the normal outdoor air heat absorption heating operation is resumed.

[0045] Note that since the exterior heat exchanger 14 may not reach the predetermined temperature Y while the vehicle is traveling, in this embodiment, the completion of defrosting is determined based on the continuous increase in temperature of the exterior heat exchanger 14 in steps S14 and S15 as described above. In addition to the above, the completion of defrosting may also be determined based on, for example, the fact that the refrigerant temperature T_ohx_out at the outlet of the exterior heat exchanger 14 is higher than the outdoor air temperature OAT or is higher than the outdoor air temperature OAT by a predetermined temperature. The completion of defrosting may also be determined based on the fact that a predetermined time has elapsed since the start of the exhaust heat recovery heating defrosting operation.

[0046] In the heating operation in an environment where frost formation is likely to occur, the vehicle air conditioner 1 switches between the normal outside-air heat absorption heating operation and the exhaust heat recovery heating and defrosting operation depending on whether or not frost formation is likely due to the above-described operation. In the exhaust heat recovery heating and defrosting operation, the defrost priority mode and the normal heating and defrosting mode are switched depending on the conditions.

[0047] [Regarding the Vehicle Air Conditioner] In the vehicle air conditioner 1 of this embodiment, refrigerant compressed by the compressor 11 flows through the interior condenser 12 and into the exterior heat exchanger 14, thereby heating the vehicle cabin and defrosting the exterior heat exchanger 14. Furthermore, by flowing a portion of the refrigerant into the interior condenser 12 and the remainder bypassing the interior condenser 12 using the bypass flow path 231, sufficient heat is provided to the exterior heat exchanger 14, allowing for highly efficient defrosting of the exterior heat exchanger 14. By adjusting the flow rate of the bypass flow path 231 to be greater than that of the interior condenser 12, more efficient defrosting of the exterior heat exchanger 14 can be achieved. While defrosting the exterior heat exchanger 14, heating using the interior condenser 12 can be maintained. Since defrosting is performed appropriately, the time during which highly efficient outdoor-air-heat-absorbing heating operation is performed is extended during heating operation.

[0048] In addition, in the exhaust heat recovery heating / defrosting operation of this embodiment, the exhaust heat from the on-board equipment is used as a heat absorption source, ensuring a sufficient heat source. Therefore, even though defrosting and heating of the exterior heat exchanger 14 are used in combination, both are sufficiently effective, and the comfort of the vehicle interior can be maintained. Furthermore, by using the heat medium heating device 43 as needed, it becomes even easier to prepare a heat source, making it easier to achieve both heating of the vehicle interior and defrosting of the exterior heat exchanger 14 at the same time.

[0049] The present invention has been described above by showing preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0050] 1: Vehicle air conditioning device 10: Refrigerant circuit, 11: Compressor, 12: Interior condenser, 131: First expansion valve, 132: Second expansion valve, 133: Third expansion valve, 14: Outdoor heat exchanger, 15: Interior evaporator, 16: Chiller, 161: Evaporator, 17: Accumulator 181: First solenoid valve, 182: Second solenoid valve, 183: Third solenoid valve, 184: Fourth solenoid valve, 191: First check valve, 192: Second check valve, 193: Third check valve, 211: First branch, 212: Second branch, 213: Third branch, 214: Fourth branch, 221: First junction, 222: Second junction, 223: Third junction, 224: Fourth junction, 231: Bypass flow path 40: Heat medium circuit, 41: In-vehicle equipment heat exchanger, 42: Chiller pump, 43: Heat medium heating device, 44: Heat exchanger 60: HVAC unit, 61: Case, 62: Air flow passage, 63: Intake unit, 64: Blower, 65: Air mix damper 80: Control device

Claims

1. A vehicular air conditioning system comprising: a refrigerant circuit including: a compressor that compresses a refrigerant; an interior condenser configured to heat the air inside the vehicle cabin through which the refrigerant flows; a bypass flow path configured to cause the refrigerant to flow while bypassing the interior condenser; and an exterior heat exchanger configured to exchange heat with air outside the vehicle cabin through which the refrigerant flows; and a control device configured to control operation of the refrigerant circuit, wherein the control device is configured to, when it is determined that there is a possibility of frost formation on the exterior heat exchanger or that frost has formed, execute a heating / defrosting operation in which the refrigerant compressed by the compressor flows into the bypass flow path and the interior condenser, and the interior condenser is used to perform the heating and defrost the exterior heat exchanger.

2. The vehicle air conditioning system according to claim 1, wherein the amount of refrigerant flowing through the bypass flow path is greater than the amount of refrigerant flowing through the interior condenser during the heating and defrosting operation.

3. A vehicle air conditioning system as described in claim 1 or 2, further comprising an evaporator configured so that the refrigerant can absorb exhaust heat from on-board equipment as the refrigerant flows, and the control device is configured to perform exhaust heat recovery heating / defrosting operation in which the refrigerant flows through the evaporator to absorb exhaust heat from the on-board equipment during the heating / defrosting operation.

4. The vehicle air conditioning system according to claim 3, further comprising a heat medium heating device configured to heat the heat medium flowing through a heat exchanger that exchanges heat with the evaporator, wherein the control device operates the heat medium heating device when it determines that the temperature of the on-board equipment is too low during the exhaust heat recovery heating and defrosting operation, or when it determines that the amount of heat absorbed by the evaporator is insufficient.

Images