JP7615942B2 - Vehicle air conditioning system - Google Patents

Description

The present invention relates to a vehicle air conditioning system that uses the same refrigerant for air conditioning the front and rear seats in the vehicle cabin to also cool the battery.

Patent Document 1 discloses a vehicle air conditioning system in which piping is connected so that the refrigerant compressed by the compressor and condensed by the 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 the 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.

JP 2000-283576 A

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, rear seat air conditioning evaporator, and battery cooling heat exchanger and flows in parallel, and piping is connected so that the refrigerant evaporated in the front seat air conditioning evaporator, rear seat air conditioning evaporator, or battery cooling heat exchanger reaches the electric compressor and is compressed by the electric compressor.

In a vehicle air conditioning system 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 some of the lubricating oil in the electric compressor circulates through these three systems along with the refrigerant, it is necessary to increase the rotation speed of the electric compressor to prevent the oil settling 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 too much to prevent the oil settling phenomenon, excess power will be consumed, worsening the vehicle's electricity consumption.

The present invention aims to improve the vehicle's power consumption by reducing the power consumption of the electric compressor while preventing 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.

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, and the refrigerant condensed in the condenser is discharged from the front seat air conditioning evaporator. A vehicle air conditioning system in which piping is connected so that the refrigerant 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, 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 is characterized in that the lower limit of the rotation speed when rotating the electric compressor is adjusted depending on whether the front seat air conditioning evaporator and the rear seat air conditioning evaporator are operating.

This vehicle air conditioning system, in a vehicle that also uses the refrigerant for air conditioning the front and rear seats in the passenger compartment to cool the battery, can prevent the occurrence of oil stagnation, while reducing power consumption in the electric compressor and improving the vehicle's electricity consumption compared to a vehicle air conditioning system that keeps the lower limit of the rotation speed of the electric compressor constant regardless of whether the evaporator for the front and rear air conditioning is operating.

The vehicle air conditioning system of the present invention is characterized in that , under conditions in which battery cooling using the battery cooling heat exchanger is required, a lower limit value of the rotational speed when rotating the electric compressor is smaller when only one of the front seat air conditioning evaporator and the rear seat air conditioning evaporator are operating than when both are operating, and a lower limit value of the rotational speed when rotating the electric compressor is smaller when both the front seat air conditioning evaporator and the rear seat air conditioning evaporator are not operating than when only one of the front seat air conditioning evaporator and the rear seat air conditioning evaporator is operating.

In one aspect of the vehicle air conditioning device of the present invention, 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 to the electric compressor via the rear seat air conditioning evaporator is greater than the pressure loss in the path from the condenser to the electric compressor via the front seat air conditioning evaporator, the pressure loss in the path from the condenser to the electric compressor via the front seat air conditioning evaporator is greater than the pressure loss in the path from the condenser to the electric compressor via the front seat air conditioning evaporator, the pressure loss in the path from the condenser to the electric compressor via the rear ... front seat air conditioning evaporator, the pressure loss in the path from the condenser to the electric compressor via the rear seat air conditioning evaporator, the pressure loss in the path from the In the case where the lower limit value of the rotation speed when rotating the electric compressor is higher in a state where the evaporator is operating, and the pressure loss in the path from the condenser to the electric compressor via the evaporator for rear seat air conditioning is smaller than the pressure loss in the path from the condenser to the electric compressor via the evaporator for front seat air conditioning, the lower limit value of the rotation speed when rotating the electric compressor may be smaller in a state where the evaporator for front seat air conditioning is not operating and the evaporator for rear seat air conditioning is operating than in a state where the evaporator for front seat air conditioning is operating and the evaporator for rear seat air conditioning is not operating.

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, the present invention can reduce the occurrence of oil stagnation while reducing power consumption in the electric compressor and improving the vehicle's power consumption.

1 is a diagram showing a configuration of a vehicle air conditioning device according to an embodiment of the present disclosure. 1 is a diagram showing a control system of a vehicle air conditioning device according to an embodiment of the present invention; FIG. 11 is a diagram showing ON/OFF of an electric compressor based on the temperature of a front seat air conditioning evaporator. 4 is a table showing lower limit values of the rotation speed of the electric compressor under conditions A to D of use of the vehicle air conditioner of the present embodiment. FIG.

Below, 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, the front seats (driver's seat and passenger seat) are arranged at the front, and the 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 the battery arranged under the floor.

The front seat air conditioning unit 2 is provided with a front seat air conditioning duct 22 with 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 can be rotated by the 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 intake mode, air is drawn from outside the vehicle into the front seat air conditioning duct 22, and in the inside air circulation mode, air is drawn from inside the vehicle cabin into the front seat air conditioning duct 22.

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

The air mix door 26, which is rotatably provided between the front seat air conditioning evaporator 25 and the heater core 27, separates the air passage that passes through the heater core 27 from the air passage that bypasses the heater core 27. The air heated by the heater core 27 and the air that bypasses the heater core 27 and remains cooled by the front seat air conditioning evaporator 25 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.

The rear seat air conditioning unit 3, like the front seat air conditioning unit 2, has a rear seat air conditioning duct 32 with 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 with the blower motor 38 to suck air from the air intake and send it toward the rear seat air conditioning evaporator 35. The entire amount of 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.

The heater core 37, like the heater core 27, is composed of tubes and fins, and water heated by the engine 1 or the water heater 51 can be passed through the tubes. The heater core 37 is disposed downstream of the air flow of the rear seat air conditioning evaporator 35 in the rear seat air conditioning duct 32, and the air passing through the heater core 37 can be heated by passing heated water through the tubes.

In the rear seat air conditioning unit 3, as in 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 air passage that passes through the heater core 37 from the air passage that bypasses 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.

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 connects to the engine 1 and the bypass pipe 52 downstream of the joining point 56.

When the three-way valve 53 is operated to allow water to flow into the engine 1 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.

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 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 bypass pipe 52 and is drawn from the bypass pipe 52 into the electric water pump 54. When circulating water in this way, 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 core 27 and the heater core 37, thereby heating the heater core 27 and the heater core 37.

The vehicle air conditioner 10 is equipped with a refrigerant circulation pipe 6 that circulates the refrigerant used for air conditioning the front and rear seats in the passenger compartment and for cooling the battery. The refrigerant circulation pipe 6 is provided with 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 passes through the condenser 62 is separated into liquid phase refrigerant and gas phase refrigerant in the receiver 63.

At a branch point 6a downstream of the receiver 63, the refrigerant circulation pipe 6 branches 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 air conditioning evaporator 25 and the rear air conditioning evaporator 35. At a branch point 6d downstream of the branch point 6a, the air conditioning pipe 6c branches into a front air conditioning pipe 6e that supplies refrigerant to the front air conditioning evaporator 25, and a rear air conditioning pipe 6f that supplies refrigerant to the rear air conditioning evaporator 35, and then merges at a junction point 6g downstream of the front air conditioning evaporator 25 and the rear air conditioning evaporator 35 to form a single air conditioning pipe 6c. The battery cooling pipe 6b and the air conditioning pipe 6c merge at a junction 6h downstream of the battery cooling unit 4 and the junction 6g to form a single refrigerant circulation pipe 6, which is connected to the electric compressor 61 downstream of the junction 6h.

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

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

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 arranged 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 arranged upstream of the battery cooling heat exchanger 43. The first pipe 45a and the second pipe 45b merge at a junction point 46 downstream of the battery cooling heat exchanger 43 to form a single battery cooling pipe 6b.

Because the battery cooling unit 4 has such a 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 in the battery cooling heat exchanger 43 and evaporates. By evaporating the liquid-phase refrigerant in the battery cooling heat exchanger 43 in this way, the battery can be cooled by the heat of vaporization. The refrigerant evaporated in the battery cooling heat exchanger 43 passes through the first pipe 45a or the second pipe 45b, then reaches the electric compressor 61 via the battery cooling pipe 6b, and is compressed by the electric compressor 61.

The vehicle air conditioning system 10 includes an ECU (electronic control unit) 20 that controls the front air conditioning unit 2, rear air conditioning unit 3, and 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 controls the front air conditioning unit 2, rear air conditioning unit 3, and 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, air mix door 26, blower motor 28, switching door 33, air mix door 36, blower motor 38, water heater 51, three-way valve 53, electric water pump 54, electric compressor 61, solenoid valve 64, solenoid valve 66, solenoid valve 41, etc.

The vehicle air conditioning system 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 between the rear seat air conditioning evaporator 35 and the heater core 37 in the rear seat air conditioning duct 32, 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.

A vehicle occupant can set the set temperature of the front air conditioning unit 2 and the rear air conditioning unit 3 by operating the operation unit 30 provided in the vehicle cabin. For example, when the occupant inputs the set temperature of the front air conditioning unit 2 into the operation unit 30, the ECU 20 calculates the target outlet temperature of the air blown out from the air outlet 21 of the front 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 outlet 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.

The ECU 20 then determines the 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 the 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. As shown in FIG. 3, the ECU 20 stops the electric compressor 61 when the temperature T of the front seat air conditioning evaporator 25 becomes lower than the target evaporator temperature Tg, and rotates the electric compressor 61 when the temperature T of the front seat air conditioning evaporator 25 becomes 1° C. higher than the target evaporator temperature Tg. Therefore, the ECU 20 operates the electric compressor 61 intermittently according to the change in the temperature of the front seat air conditioning evaporator 25.

When the passenger inputs the set temperature of the rear seat air conditioning unit 3 into the operation unit 30, the ECU 20 calculates the target 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 blow temperature and the water temperature, and controls the blower motor 38 and the air mix door 36. The ECU 20 detects the water temperature from the water temperature sensor 58 provided in the water heater 51.

The ECU 20 then determines the 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 the ON/OFF of the electric compressor 61 so that the post-evaporator temperature detected by the air temperature sensor 39 installed 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 will operate the electric compressor 61 intermittently depending on changes in the post-evaporator temperature.

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, if the temperature T of the front seat air conditioning evaporator 25 becomes lower than the target evaporator temperature Tg, or if 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, if the temperature T of the front seat air conditioning evaporator 25 becomes 1°C higher than the target evaporator temperature Tg, or if the post-evaporator temperature of the rear seat air conditioning evaporator 35 becomes 1°C higher than the target post-evaporator temperature, the ECU 20 rotates the electric compressor 61.

Furthermore, the ECU 20 can circulate the refrigerant through the battery cooling unit 4 to cool the battery arranged under the floor. 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 below the predetermined value.

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 is higher than a predetermined value and rotates the electric compressor 61, and determines that there is no battery cooling request when the battery temperature is lower than the predetermined value and stops the electric compressor 61. In addition, when the ECU 20 determines that there is a battery cooling request when the battery temperature is higher than the predetermined value and either or both of the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35 are to be operated, 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.

In the vehicle air conditioner 10, when the ECU 20 determines that there is a battery cooling request, under usage condition A in which both the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35 are operated, 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.

In addition, under usage condition B, in which the ECU 20 determines that there is a battery cooling request and the front seat air conditioning evaporator 25 is operated but the rear seat air conditioning evaporator 35 is not operated, 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. Unlike usage condition A, usage condition B does not circulate refrigerant through the rear seat air conditioning unit 3, so the lower limit of the rotation speed of the electric compressor 61 is smaller than that under usage condition A.

In addition, 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 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. Unlike usage condition B, usage condition C does not circulate the refrigerant through the front seat air conditioning unit 2, so the lower limit of the rotation speed of the electric compressor 61 is smaller than that under usage condition B.

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

Unlike use condition A, use condition D does not circulate the refrigerant to the front seat air conditioning unit 2, so the lower limit of the rotation speed of the electric compressor 61 is smaller than that of use condition A.Unlike use condition C, use condition D circulates the refrigerant to the rear seat air conditioning unit 3, so the lower limit of the rotation speed of the electric compressor 61 is larger than that of use condition C.Unlike use condition B, 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 of the rotation speed of the electric compressor 61 is larger than that of use condition B.

In the vehicle air conditioning system 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 rear seat air conditioning evaporator 35 to the electric compressor 61 is greater than the pressure loss from the condenser 62 to the front seat air conditioning evaporator 25 to the electric compressor 61.

The vehicle air conditioner 10 thus changes the lower limit of the rotation speed when rotating the electric compressor 61 under operating conditions A to D depending on whether the front seat air conditioning evaporator 25 and the rear seat air conditioning evaporator 35 are operating. This prevents the oil from stagnation, while reducing the power consumption of the electric compressor 61 and improving the vehicle's electricity consumption compared to a vehicle air conditioner that keeps 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.

Note that in this embodiment, the numerical values shown in FIG. 4 as the lower limit values of the rotation speed of the electric compressor 61 under the usage conditions A to D are numerical values 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 numerical values different from the numerical values shown in FIG. 4.

<Supplementary description of 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.

LIST OF SYMBOLS 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 (2)

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. The vehicle air conditioning system according to 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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