Vehicle air conditioning system

Abstract

To enhance an electricity consumption rate of a vehicle by restraining electricity consumed by an electric compressor while restraining oil asleep phenomenon from occurring.SOLUTION: An air conditioner 10 for a vehicle comprises an electric compressor 61, a condenser 62, an evaporator 25 for front seat air-conditioning and an evaporator 35 for rear seat air-conditioning which evaporate a coolant condensed at the condenser 62, and a heat exchanger 43 for battery cooling. Therein, piping is connected so that the coolant condensed at the condenser 62 diverges into the evaporator 25 for front seat air-conditioning, the evaporator 35 for rear seat air-conditioning and the heat exchanger 43 for battery cooling and then flows in parallel with each other, and the coolant evaporated at the evaporator 25 for front seat air-conditioning, the evaporator 35 for rear seat air-conditioning or the heat exchanger 43 for battery cooling is compressed at the compressor 61. The air conditioner for the vehicle adjusts a lower limit value of rotary speed when rotating the electric compressor 61 according to whether or not the evaporator 25 for front seat air-conditioning and the evaporator 35 for rear seat air-conditioning is in operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air conditioner for a vehicle that uses a refrigerant for air conditioning the front and rear seats in a vehicle interior also for cooling a battery. [Background technology]

[0002] Patent Document 1 discloses a vehicle air conditioning system in which piping is connected so that refrigerant compressed in a compressor and condensed in a condenser branches off to an evaporator for front seat air conditioning and an evaporator for rear seat air conditioning and flows in parallel, and piping is connected so that refrigerant evaporated in the evaporator for front seat air conditioning and the evaporator for rear seat air conditioning reaches the compressor and is compressed by the compressor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-283576 A Summary of the Invention [Problem to be solved by the invention]

[0004] In electric vehicles or hybrid cars equipped with an electric motor as a power source for driving, the refrigerant used for air conditioning the front and rear seats in the passenger compartment may also be used to cool the battery. In such vehicle air conditioning systems, piping is connected so that the refrigerant compressed by the electric compressor and condensed by the condenser branches off to the front seat air conditioning evaporator, the rear seat air conditioning evaporator, and the battery cooling heat exchanger and flows in parallel, and piping is connected so that the refrigerant evaporated in the front seat air conditioning evaporator, the rear seat air conditioning evaporator, or the battery cooling heat exchanger reaches the electric compressor and is compressed by the electric compressor.

[0005] In a vehicle air conditioner with piping connected in this way, the refrigerant flows from one electric compressor to three separate systems: the front seat air conditioning evaporator, the rear seat air conditioning evaporator, and the battery cooling heat exchanger. Since a portion of the lubricating oil of the electric compressor circulates through these three systems together with the refrigerant, it is necessary to increase the rotation speed of the electric compressor to prevent the oil stagnation phenomenon, in which the lubricating oil adheres to the inner walls of the battery cooling heat exchanger and piping, and does not return to the electric compressor. If the amount of lubricating oil returning to the electric compressor is insufficient, poor lubrication of the electric compressor occurs, adversely affecting the durability of the electric compressor. However, if the rotation speed of the electric compressor is increased excessively to prevent the oil stagnation phenomenon, excess power will be consumed, worsening the vehicle's electricity consumption.

[0006] Therefore, the present invention aims to reduce the occurrence of oil stagnation in a vehicle in which the refrigerant used for air conditioning the front and rear seats in the passenger compartment is also used to cool the battery, while reducing the power consumption of the electric compressor and improving the vehicle's electricity consumption. [Means for solving the problem]

[0007] The vehicle air conditioning system according to the present invention is mounted on an electric vehicle or hybrid car equipped with an electric motor as a driving power source, and includes one electric compressor that compresses and discharges a refrigerant, one condenser that cools and condenses the refrigerant discharged from the electric compressor, a front seat air conditioning evaporator that evaporates the refrigerant condensed in the condenser, a rear seat air conditioning evaporator that evaporates the refrigerant condensed in the condenser, and a battery cooling heat exchanger that evaporates the refrigerant condensed in the condenser, A vehicle air conditioning system in which piping is connected so that the refrigerant branches off and flows in parallel to a front seat air conditioning evaporator, a rear seat air conditioning evaporator, and the battery cooling heat exchanger, and piping is connected so that the refrigerant evaporated in the front seat air conditioning evaporator, the rear seat air conditioning evaporator, or the battery cooling heat exchanger reaches the electric compressor and is compressed by the electric compressor, and which is characterized in that a lower limit value of the rotational speed when rotating the electric compressor is adjusted depending on whether or not each of the front seat air conditioning evaporator and the rear seat air conditioning evaporator is operating.

[0008] This vehicle air conditioning system, in a vehicle that uses the refrigerant used to air condition the front and rear seats in the passenger compartment also to cool the battery, prevents the occurrence of oil stagnation, while reducing power consumption in the electric compressor and improving the vehicle's electricity consumption, compared to vehicle air conditioning systems that keep the lower limit of the rotation speed of the electric compressor constant regardless of whether the front seat air conditioning evaporator and the rear seat air conditioning evaporator are operating.

[0009] Air conditioner for vehicle according to the present invention teeth,Under conditions in which battery cooling using the battery cooling heat exchanger is required, a lower limit value of the rotation speed when rotating the electric compressor is smaller in a state in which only one of the front seat air conditioning evaporator and the rear seat air conditioning evaporator are operating than in a state in which both of the front seat air conditioning evaporator and the rear seat air conditioning evaporator are operating, and a lower limit value of the rotation speed when rotating the electric compressor is smaller in a state in which neither the front seat air conditioning evaporator nor the rear seat air conditioning evaporator is operating than in a state in which only one of the front seat air conditioning evaporator and the rear seat air conditioning evaporator is operating. It is characterized by .

[0010] In one aspect of the vehicle air conditioner of the present invention, when battery cooling using the heat exchanger for cooling a battery is required and only one of the front seat air conditioning evaporator and the rear seat air conditioning evaporator is operating, if a pressure loss in a path from the condenser to the electric compressor via the rear seat air conditioning evaporator is greater than a pressure loss in a path from the condenser to the electric compressor via the front seat air conditioning evaporator, a state in which the front seat air conditioning evaporator is not operating and the rear seat air conditioning evaporator is not operating is more preferable than a state in which the front seat air conditioning evaporator is operating and the rear seat air conditioning evaporator is not operating. In the case where a lower limit value of the rotation speed when rotating the electric compressor is larger in a state where the evaporator is operating and a pressure loss in a path from the condenser via the rear seat air conditioning evaporator to the electric compressor is smaller than a pressure loss in a path from the condenser via the front seat air conditioning evaporator to the electric compressor, a lower limit value of the rotation speed when rotating the electric compressor may be smaller in a state where the front seat air conditioning evaporator is not operating and the rear seat air conditioning evaporator is operating than in a state where the front seat air conditioning evaporator is operating and the rear seat air conditioning evaporator is not operating. Effect of the Invention

[0011] The present invention can reduce the occurrence of oil stagnation in a vehicle in which the refrigerant used to air condition the front and rear seats in the passenger compartment is also used to cool the battery, thereby reducing power consumption in the electric compressor and improving the vehicle's electricity consumption. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram showing a configuration of a vehicle air conditioning device according to an embodiment of the present disclosure. [Diagram 2] 1 is a diagram showing a control system of a vehicle air conditioning device according to an embodiment of the present invention; [Diagram 3] FIG. 4 is a diagram showing ON / OFF of an electric compressor based on the temperature of a front seat air conditioning evaporator. [Figure 4] 4 is a table showing lower limits of the rotation speed of the electric compressor under conditions A to D of use of the vehicle air conditioner according to the present embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a vehicle air conditioner 10 according to an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of the vehicle air conditioner 10. The vehicle air conditioner 10 is mounted on a hybrid car equipped with an engine 1 and an electric motor (not shown) as a driving power source. In the passenger compartment of this hybrid car, front seats (driver's seat and passenger seat) are arranged at the front, and rear seats are arranged behind the front seats. A battery is arranged under the floor of the hybrid car. As shown in FIG. 1, the vehicle air conditioner 10 includes a front seat air conditioning unit 2 that conditions the front seats in the passenger compartment, a rear seat air conditioning unit 3 that conditions the rear seats in the passenger compartment, and a battery cooling unit 4 that cools a battery arranged under the floor.

[0014] The front seat air conditioning unit 2 includes a front seat air conditioning duct 22 having an air intake formed at one open end and an air outlet 21 formed at the other open end. A switching door 23 is provided near the air intake of the front seat air conditioning duct 22, and a blower fan 24, a front seat air conditioning evaporator 25, an air mix door 26, and a heater core 27 are provided inside the front seat air conditioning duct 22. In the front seat air conditioning unit 2, the blower fan 24 is rotated by a blower motor 28 to suck air from the air intake and send it toward the front seat air conditioning evaporator 25. The entire amount of air sucked into the front seat air conditioning duct 22 from the air intake passes through the front seat air conditioning evaporator 25. In the front seat air conditioning unit 2, the switching door 23 can be rotated to switch between an outside air introduction mode and an inside air circulation mode. In the outside air introduction mode, air is drawn into the front seat air conditioning duct 22 from outside the vehicle, and in the inside air circulation mode, air is drawn into the front seat air conditioning duct 22 from inside the vehicle compartment.

[0015] Heater core 27 is composed of tubes and fins, and water heated by engine 1 or water heater 51 can be passed through the tubes. Heater core 27 is disposed downstream of the air flow of front seat air conditioning evaporator 25 in front seat air conditioning duct 22, and can heat the air passing through heater core 27 by passing heated water through the tubes.

[0016] An air mix door 26 rotatably provided between the front seat air conditioning evaporator 25 and the heater core 27 separates an air passage that passes through the heater core 27 from an air passage that bypasses the heater core 27. The air heated by the heater core 27 and the air that remains cooled by the front seat air conditioning evaporator 25 by bypassing the heater core 27 are mixed near the air outlet 21 and blown out from the air outlet 21. Therefore, the front seat air conditioning unit 2 can control the temperature of the conditioned air blown out from the air outlet 21 by controlling the opening degree of the air mix door 26 to adjust the amount of air passing through the heater core 27 and the amount of air bypassing the heater core 27.

[0017] The rear seat air conditioning unit 3, like the front seat air conditioning unit 2, includes a rear seat air conditioning duct 32 having an air intake formed at one open end and an air outlet 31 formed at the other open end, a switching door 33 is provided near the air intake, and a blower fan 34, a rear seat air conditioning evaporator 35, an air mix door 36, and a heater core 37 are provided inside the rear seat air conditioning duct 32. The rear seat air conditioning unit 3 can rotate the blower fan 34 using a blower motor 38 to suck air from the air intake and send it toward the rear seat air conditioning evaporator 35. All of the air sucked into the rear seat air conditioning duct 32 from the air intake passes through the rear seat air conditioning evaporator 35. The rear seat air conditioning unit 3 can be switched between an outside air introduction mode and an inside air circulation mode by rotating the switching door 33.

[0018] Like heater core 27, heater core 37 is composed of tubes and fins, and water heated by engine 1 or water heater 51 can flow through the tubes. Heater core 37 is disposed downstream of the air flow of rear seat air conditioning evaporator 35 in rear seat air conditioning duct 32, and can heat the air passing through heater core 37 by passing heated water through the tubes.

[0019] In the rear seat air conditioning unit 3, similarly to the front seat air conditioning unit 2, an air mix door 36 provided between the rear seat air conditioning evaporator 35 and the heater core 37 separates the passage of air passing through the heater core 37 from the passage of air bypassing the heater core 37, and the air separated by the air mix door 36 is mixed near the air outlet 31. Therefore, the rear seat air conditioning unit 3 can control the temperature of the conditioned air blown out from the air outlet 31 by controlling the opening degree of the air mix door 36 to adjust the amount of air passing through the heater core 37 and the amount of air bypassing the heater core 37.

[0020] Between the heater core 27 and the heater core 37 and the engine 1, a water circulation pipe 5 is provided through which water heated by the engine 1 circulates. The water circulation pipe 5 is provided with a bypass pipe 52 that bypasses the engine 1 and a three-way valve 53, and by operating the three-way valve 53, it is possible to switch whether water flows through the engine 1 or the bypass pipe 52. The water circulation pipe 5 is provided with an electric water pump 54 downstream of the three-way valve 53, a water heating heater 51 downstream of the electric water pump 54, and a branch point 55 downstream of the water heating heater 51. The water circulation pipe 5 branches at the branch point 55 so that water flows in parallel to the heater core 27 and the heater core 37, joins at a joining point 56 provided downstream of the heater core 27 and the heater core 37, and is connected to the engine 1 and the bypass pipe 52 downstream of the joining point 56.

[0021] When the three-way valve 53 is operated to allow water to flow into the engine 1 in order to cool the engine 1, the electric water pump 54 can draw in water from the engine 1 and send it to the heater core 27 and the heater core 37. The cooling water that flows through the tubes of the heater core 27 and the heater core 37 returns to the engine 1 and is used to cool the engine 1, and is then drawn into the electric water pump 54. In this way, the water heated by the engine 1 circulates and flows through the tubes of the heater core 27 and the heater core 37, thereby heating the heater core 27 and the heater core 37.

[0022] Furthermore, when the three-way valve 53 is operated to allow water to flow through the bypass pipe 52, the electric water pump 54 can draw in water from the bypass pipe 52 and send it to the heater cores 27 and 37. The cooling water that has flowed through the tubes of the heater cores 27 and 37 returns to the bypass pipe 52 and is drawn from the bypass pipe 52 into the electric water pump 54. When circulating water in this manner, the water sent out from the electric water pump 54 is heated by the water heater 51, and the water heated by the water heater 51 is caused to flow through the tubes of the heater cores 27 and 37, thereby heating the heater cores 27 and 37.

[0023] The vehicle air conditioner 10 includes a refrigerant circulation pipe 6 that circulates a refrigerant used for air conditioning the front and rear seats in the vehicle cabin and for cooling the battery. The refrigerant circulation pipe 6 includes an electric compressor 61 that compresses the refrigerant to a high temperature and high pressure and discharges it, a condenser 62 that cools and condenses the refrigerant discharged from the electric compressor 61, and a receiver 63. The condenser 62 can cool and liquefy the refrigerant by exchanging heat with outside air. The refrigerant that has passed through the condenser 62 is separated into a liquid-phase refrigerant and a gas-phase refrigerant in the receiver 63.

[0024] The refrigerant circulation pipe 6 branches at a branch point 6a downstream of the receiver 63 into a battery cooling pipe 6b that supplies refrigerant to the battery cooling unit 4, and an air conditioning pipe 6c that supplies refrigerant to the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35. The air conditioning pipe 6c branches at a branch point 6d downstream of the branch point 6a into a front seat air conditioning pipe 6e that supplies refrigerant to the front seat air conditioning evaporator 25 and a rear seat air conditioning pipe 6f that supplies refrigerant to the rear seat air conditioning evaporator 35, and these pipes join at a junction point 6g downstream of the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35 to form a single air conditioning pipe 6c. The battery cooling piping 6b and the air conditioning piping 6c merge at a junction 6h downstream of the battery cooling unit 4 and the junction 6g to become a single refrigerant circulating piping 6, and are connected to an electric compressor 61 downstream of the junction 6h.

[0025] A solenoid valve 64 and an expansion valve 65 are provided in the front seat air conditioning pipe 6e upstream of the front seat air conditioning evaporator 25. When the solenoid valve 64 is open, the liquid phase refrigerant condensed in the condenser 62 passes through the solenoid valve 64 and is then depressurized by the expansion valve 65, and the depressurized refrigerant is evaporated in the front seat air conditioning evaporator 25 by absorbing heat from the conditioned air. By evaporating the liquid phase refrigerant in the front seat air conditioning evaporator 25 in this manner, the air passing through the front seat air conditioning evaporator 25 can be cooled. The refrigerant evaporated in the front seat air conditioning evaporator 25 reaches the electric compressor 61 via the front seat air conditioning pipe 6e and the air conditioning pipe 6c, and is compressed by the electric compressor 61.

[0026] The rear seat air conditioning pipe 6f is also provided with a solenoid valve 66 and an expansion valve 67 upstream of the rear seat air conditioning evaporator 35. When the solenoid valve 66 is open, the liquid phase refrigerant condensed in the condenser 62 passes through the solenoid valve 66 and is then depressurized by the expansion valve 67, and the depressurized refrigerant is evaporated in the rear seat air conditioning evaporator 35 by absorbing heat from the conditioned air. By evaporating the liquid phase refrigerant in this manner in the rear seat air conditioning evaporator 35, the air passing through the rear seat air conditioning evaporator 35 can be cooled. The refrigerant evaporated in the rear seat air conditioning evaporator 35 reaches the electric compressor 61 via the rear seat air conditioning pipe 6f and the air conditioning pipe 6c, and is compressed by the electric compressor 61.

[0027] The battery cooling unit 4 includes one solenoid valve 41, two expansion valves 42, and two battery cooling heat exchangers 43. The solenoid valve 41 is provided in the battery cooling pipe 6b, and the battery cooling pipe 6b branches into a first pipe 45a and a second pipe 45b at a branch point 44 downstream of the solenoid valve 41. The first pipe 45a is provided with an expansion valve 42 and a battery cooling heat exchanger 43, and the expansion valve 42 is disposed upstream of the battery cooling heat exchanger 43. The second pipe 45b is also provided with an expansion valve 42 and a battery cooling heat exchanger 43, similar to the first pipe 45a, and the expansion valve 42 is disposed upstream of the battery cooling heat exchanger 43. The first pipe 45a and the second pipe 45b join at a joining point 46 downstream of the battery cooling heat exchanger 43 to form a single battery cooling pipe 6b.

[0028] Because the battery cooling unit 4 has this configuration, when the solenoid valve 41 is open, the liquid phase refrigerant condensed in the condenser 62 passes through the solenoid valve 41 and is then depressurized by the expansion valve 42, and the depressurized refrigerant absorbs heat from the battery and evaporates in the battery cooling heat exchanger 43. By evaporating the liquid phase refrigerant in the battery cooling heat exchanger 43 in this manner, the battery can be cooled by the heat of vaporization. The refrigerant evaporated in the battery cooling heat exchanger 43 passes through the first piping 45a or the second piping 45b, and then reaches the electric compressor 61 via the battery cooling piping 6b, and is compressed by the electric compressor 61.

[0029] The vehicle air conditioner 10 includes an ECU (electronic control unit) 20 that controls the front seat air conditioning unit 2, the rear seat air conditioning unit 3, and the battery cooling unit 4. The ECU 20 has a CPU, which is an arithmetic processing unit, and storage units such as RAM and ROM, and executes control of the front seat air conditioning unit 2, the rear seat air conditioning unit 3, and the battery cooling unit 4 by performing signal processing according to a program pre-stored in the ROM while utilizing the temporary storage function of the RAM. As shown in Fig. 2, the ECU 20 controls the switching door 23, the air mix door 26, the blower motor 28, the switching door 33, the air mix door 36, the blower motor 38, the water heater 51, the three-way valve 53, the electric water pump 54, the electric compressor 61, the solenoid valve 64, the solenoid valve 66, the solenoid valve 41, and the like.

[0030] The vehicle air conditioner 10 includes a water temperature sensor 57 provided on the engine 1, a water temperature sensor 58 provided on the water heater 51, a temperature sensor 29 provided on the fins of the front seat air conditioning evaporator 25, an air temperature sensor 39 provided in the rear seat air conditioning duct 32 between the rear seat air conditioning evaporator 35 and the heater core 37, a room temperature sensor 71 that detects the room temperature near the front seats, a room temperature sensor 72 that detects the room temperature near the rear seats, an outside air temperature sensor 73 that detects the temperature of the air outside the vehicle, a solar radiation sensor 74 that detects the amount of solar radiation, and a battery temperature sensor 75 that detects the temperature of the battery. The outputs of these sensors are all input to the ECU 20.

[0031] An occupant of the vehicle can set the set temperature of the front seat air conditioning unit 2, the set temperature of the rear seat air conditioning unit 3, etc., by operating an operation unit 30 provided in the vehicle cabin. For example, when an occupant inputs the set temperature of the front seat air conditioning unit 2 into the operation unit 30, the ECU 20 calculates a target blowing temperature of the air blown out from the air outlet 21 of the front seat air conditioning unit 2 from the set temperature, the room temperature near the front seats, the outside air temperature, and the amount of solar radiation, and determines the air volume of the blower fan 24 and the opening degree of the air mix door 26 from the target blowing temperature and the water temperature to control the blower motor 28 and the air mix door 26. The ECU 20 detects the water temperature from a water temperature sensor 58 provided in the water heater 51.

[0032] The ECU 20 then determines a target evaporator temperature Tg of the front seat air conditioning evaporator 25 from the set temperature of the front seat air conditioning unit 2, the room temperature near the front seats, the outside air temperature, and the amount of solar radiation, and controls ON / OFF of the electric compressor 61 so that the temperature T of the front seat air conditioning evaporator 25 becomes the target evaporator temperature Tg. The ECU 20 stores a map of the target evaporator temperature Tg based on the set temperature of the front seat air conditioning unit 2, the room temperature near the front seats, the outside air temperature, and the amount of solar radiation, and the ECU 20 determines the target evaporator temperature Tg based on this map. The ECU 20 detects the temperature T of the front seat air conditioning evaporator 25 using a temperature sensor 29 provided on the fin of the front seat air conditioning evaporator 25. 3, when the temperature T of the front seat air conditioning evaporator 25 becomes lower than the target evaporator temperature Tg, the ECU 20 stops the electric compressor 61, and when the temperature T of the front seat air conditioning evaporator 25 becomes 1° C. higher than the target evaporator temperature Tg, the ECU 20 rotates the electric compressor 61. Therefore, the ECU 20 operates the electric compressor 61 intermittently in accordance with the change in the temperature of the front seat air conditioning evaporator 25.

[0033] Furthermore, when an occupant inputs the set temperature of the rear seat air conditioning unit 3 into the operation section 30, the ECU 20 calculates a target blowing temperature of the air blown out from the air outlet 31 of the rear seat air conditioning unit 3 from the set temperature, the room temperature near the rear seat, the outside air temperature, and the amount of solar radiation, and determines the air volume of the blower fan 34 and the opening degree of the air mix door 36 from the target blowing temperature and the water temperature to control the blower motor 38 and the air mix door 36. The ECU 20 detects the water temperature from a water temperature sensor 58 provided in the water heater 51.

[0034] The ECU 20 then determines a target post-evaporator temperature from the set temperature of the rear seat air conditioning unit 3, the room temperature near the rear seat, the outside air temperature, and the amount of solar radiation, and controls ON / OFF of the electric compressor 61 so that the post-evaporator temperature detected by the air temperature sensor 39 provided between the rear seat air conditioning evaporator 35 and the heater core 37 in the rear seat air conditioning duct 32 becomes the target post-evaporator temperature. The ECU 20 stores a map of the target post-evaporator temperature based on the set temperature of the front seat air conditioning unit 2, the room temperature near the rear seat, the outside air temperature, and the amount of solar radiation, and the ECU 20 determines the target post-evaporator temperature based on this map. The ECU 20 stops the electric compressor 61 when the post-evaporator temperature becomes lower than the target post-evaporator temperature, and rotates the electric compressor 61 when the post-evaporator temperature becomes 1°C higher than the target post-evaporator temperature. Therefore, the ECU 20 operates the electric compressor 61 intermittently in response to changes in the temperature after the evaporator.

[0035] The ECU 20 can also operate the front seat air conditioning unit 2 and the rear seat air conditioning unit 3 simultaneously. In this case, when the temperature T of the front seat air conditioning evaporator 25 becomes lower than the target evaporator temperature Tg, or when the post-evaporator temperature of the rear seat air conditioning evaporator 35 becomes lower than the target post-evaporator temperature, the ECU 20 stops the electric compressor 61. Then, when the temperature T of the front seat air conditioning evaporator 25 becomes higher by 1° C. than the target evaporator temperature Tg, or when the post-evaporator temperature of the rear seat air conditioning evaporator 35 becomes higher by 1° C. than the target post-evaporator temperature, the ECU 20 rotates the electric compressor 61.

[0036] Furthermore, the ECU 20 can cool the battery arranged under the floor by circulating the refrigerant through the battery cooling unit 4. The ECU 20 determines whether or not there is a request for battery cooling based on the battery temperature detected by the battery temperature sensor 75. The ECU 20 determines that there is a request for battery cooling when the battery temperature is higher than a predetermined value, and determines that there is no request for battery cooling when the battery temperature is equal to or lower than the predetermined value.

[0037] When the ECU 20 closes the solenoid valves 64 and 66 and does not operate the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35, the ECU 20 determines that there is a battery cooling request when the battery temperature becomes higher than a predetermined value and rotates the electric compressor 61, and determines that there is no battery cooling request when the battery temperature becomes lower than the predetermined value and stops the electric compressor 61. When the ECU 20 determines that the battery temperature is higher than the predetermined value and there is a battery cooling request, and operates either or both of the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35, the ECU 20 rotates or stops the electric compressor 61 based on the temperature T of the front seat air conditioning evaporator 25 and the post-evaporator temperature of the rear seat air conditioning evaporator 35.

[0038] In the vehicle air conditioner 10, under usage condition A in which both the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35 are operated when the ECU 20 determines that there is a battery cooling request, the refrigerant circulates through the front seat air conditioning unit 2, the rear seat air conditioning unit 3, and the battery cooling unit 4. Under this usage condition A, in order to prevent the occurrence of the oil stagnation phenomenon, as shown in FIG. 4, the lower limit of the rotation speed of the electric compressor 61 must be set to 4000 rpm.

[0039] Furthermore, under usage condition B in which the front seat air conditioning evaporator 25 is operated but the rear seat air conditioning evaporator 35 is not operated when the ECU 20 determines that there is a battery cooling request, the refrigerant circulates through the front seat air conditioning unit 2 and the battery cooling unit 4. Under this usage condition B, in order to prevent the occurrence of the oil stagnation phenomenon, the lower limit of the rotation speed of the electric compressor 61 must be set to 3500 rpm, as shown in Fig. 4. Under usage condition B, unlike usage condition A, the refrigerant is not circulated through the rear seat air conditioning unit 3, and therefore the lower limit of the rotation speed of the electric compressor 61 is smaller than under usage condition A.

[0040] Furthermore, under usage condition C in which neither the front seat air conditioning evaporator 25 nor the rear seat air conditioning evaporator 35 is operated when the ECU 20 determines that there is a battery cooling request, the refrigerant circulates only through the battery cooling unit 4. Under this usage condition C, in order to prevent the occurrence of the oil stagnation phenomenon, the lower limit of the rotation speed of the electric compressor 61 must be set to 3000 rpm, as shown in Fig. 4. Under usage condition C, unlike usage condition B, the refrigerant is not circulated through the front seat air conditioning unit 2, and therefore the lower limit of the rotation speed of the electric compressor 61 is smaller than under usage condition B.

[0041] Furthermore, under usage condition D in which the front seat air conditioning evaporator 25 is not operated and the rear seat air conditioning evaporator 35 is operated when the ECU 20 determines that there is a battery cooling request, the refrigerant circulates through the rear seat air conditioning unit 3 and the battery cooling unit 4. Under this usage condition D, in order to prevent the occurrence of the oil stagnation phenomenon, as shown in FIG. 4, the lower limit of the rotation speed of the electric compressor 61 must be set to 3750 rpm.

[0042] Unlike the use condition A, the use condition D does not circulate the refrigerant to the front seat air conditioning unit 2, so the lower limit value of the rotation speed of the electric compressor 61 is smaller than that of the use condition A. And unlike the use condition C, the use condition D circulates the refrigerant to the rear seat air conditioning unit 3, so the lower limit value of the rotation speed of the electric compressor 61 is larger than that of the use condition C. And unlike the use condition B, the use condition D circulates the refrigerant to the rear seat air conditioning unit 3 instead of the front seat air conditioning unit 2, but the pressure loss from the condenser 62 to the electric compressor 61 via the rear seat air conditioning evaporator 35 is larger than the pressure loss from the condenser 62 to the electric compressor 61 via the front seat air conditioning evaporator 25, so the lower limit value of the rotation speed of the electric compressor 61 is larger than that of the use condition B.

[0043] In the vehicle air conditioner 10, the electric compressor 61 and the condenser 62 are disposed at the front of the vehicle, so the piping length from the electric compressor 61 and the condenser 62 to the rear seat air conditioning evaporator 35 is longer than the piping length from the electric compressor 61 and the condenser 62 to the front seat air conditioning evaporator 25. Therefore, the pressure loss from the condenser 62 to the electric compressor 61 via the rear seat air conditioning evaporator 35 is larger than the pressure loss from the condenser 62 to the electric compressor 61 via the front seat air conditioning evaporator 25.

[0044] In this way, the vehicle air conditioner 10 changes the lower limit of the rotation speed when rotating the electric compressor 61 under usage conditions A to D depending on whether the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35 are operating or not. Therefore, while preventing the occurrence of the oil stagnation phenomenon, it is possible to reduce the power consumption of the electric compressor 61 and improve the vehicle's electricity consumption compared to vehicle air conditioners that always keep the lower limit of the rotation speed of the electric compressor 61 constant regardless of whether the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35 are operating or not.

[0045] 4 as the lower limit values ​​of the rotation speed of the electric compressor 61 under the usage conditions A to D in this embodiment are shown as examples. If the performance of the electric compressor 61 or the piping length is different, the lower limit values ​​of the rotation speed of the electric compressor 61 under the usage conditions A to D will be different from the values ​​shown in FIG.

[0046] <Supplementary explanation of the embodiment> The vehicle air conditioner of the present disclosure is not limited to the above-mentioned embodiment, and may be implemented in various forms within the scope of the gist of the present disclosure. For example, the pressure loss from the condenser to the electric compressor via the rear seat air conditioning evaporator may be smaller than the pressure loss from the condenser to the electric compressor via the front seat air conditioning evaporator. The vehicle air conditioner may also be installed in an engine-less electric vehicle. In this case, the water passing through the tubes of the heater core cannot be heated by the engine, but is heated by the water heater. [Explanation of symbols]

[0047] 1 engine, 2 front seat air conditioning unit, 3 rear seat air conditioning unit, 4 battery cooling unit, 5 water circulation pipe, 6 refrigerant circulation pipe, 6a branch point, 6b battery cooling pipe, 6c air conditioning pipe, 6d branch point, 6e front seat air conditioning pipe, 6f rear seat air conditioning pipe, 6g, 6h junction point, 10 vehicle air conditioning device, 20 ECU, 21 air outlet, 22 front seat air conditioning duct, 23 switching door, 24 blower fan, 25 front seat air conditioning evaporator, 26 air mix door, 27 heater core, 28 blower motor, 29 temperature sensor, 30 operation unit, 31 air outlet, 32 rear seat air conditioning duct, 33 switching door, 34 blower fan, 35 rear seat air conditioning evaporator, 36 air mix door, 37 heater core, 38 Blower motor, 39 air temperature sensor, 41 solenoid valve, 42 expansion valve, 43 battery cooling heat exchanger, 44 branch point, 45a first pipe, 45b second pipe, 46 junction point, 51 water heater, 52 bypass pipe, 53 three-way valve, 54 electric water pump, 55 branch point, 56 junction point, 57, 58 water temperature sensor, 61 electric compressor, 62 condenser, 63 receiver, 64, 66 solenoid valve, 65, 67 expansion valve, 71, 72 room temperature sensor, 73 outside air temperature sensor, 74 solar radiation sensor, 75 battery temperature sensor.

Claims

1. The vehicle is mounted on an electric vehicle or hybrid vehicle equipped with an electric motor as a power source for driving the vehicle. One electric compressor that compresses and discharges a refrigerant; a condenser for cooling and condensing the refrigerant discharged from the electric compressor; a front seat air conditioning evaporator that evaporates the refrigerant condensed by the condenser; a rear seat air conditioning evaporator that evaporates the refrigerant condensed by the condenser; a battery cooling heat exchanger that evaporates the refrigerant condensed in the condenser, Pipes are connected so that the refrigerant condensed in the condenser branches off and flows in parallel to the front seat air conditioning evaporator, the rear seat air conditioning evaporator, and the battery cooling heat exchanger, a piping is connected so that the refrigerant evaporated in the front seat air conditioning evaporator, the rear seat air conditioning evaporator, or the battery cooling heat exchanger reaches the electric compressor and is compressed by the electric compressor, adjusting a lower limit value of a rotation speed when rotating the electric compressor depending on whether the front seat air conditioning evaporator and the rear seat air conditioning evaporator are operating, Under conditions where battery cooling using the battery cooling heat exchanger is required, a lower limit value of a rotation speed when rotating the electric compressor is smaller in a state where only one of the evaporator for the front seat air conditioning and the evaporator for the rear seat air conditioning is operating than in a state where both the evaporator for the front seat air conditioning and the evaporator for the rear seat air conditioning are operating; a lower limit value of the rotational speed at which the electric compressor is rotated is smaller in a state in which neither the front seat air conditioning evaporator nor the rear seat air conditioning evaporator is operating than in a state in which only one of the front seat air conditioning evaporator and the rear seat air conditioning evaporator is operating.

2. A vehicle air conditioning system as described in claim 1, When battery cooling using the battery cooling heat exchanger is required and only one of the front seat air conditioning evaporator and the rear seat air conditioning evaporator is operating, If the pressure loss in the path from the condenser via the rear seat air conditioning evaporator to the electric compressor is greater than the pressure loss in the path from the condenser via the front seat air conditioning evaporator to the electric compressor, the lower limit value of the rotation speed when rotating the electric compressor is greater in a state where the front seat air conditioning evaporator is not operating and the rear seat air conditioning evaporator is operating than in a state where the front seat air conditioning evaporator is operating and the rear seat air conditioning evaporator is not operating; a lower limit value of the rotational speed of the electric compressor is smaller in a state where the front seat air conditioning evaporator is not operating and the rear seat air conditioning evaporator is operating than in a state where the front seat air conditioning evaporator is operating and the rear seat air conditioning evaporator is not operating, when a pressure loss in a path from the condenser to the electric compressor via the front seat air conditioning evaporator is smaller than a pressure loss in a path from the condenser to the electric compressor via the front seat air conditioning evaporator.

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