JP2024019998A - Air conditioner for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner for vehicle which can suppress reduction in heating capacity.

SOLUTION: An air conditioning device 10 used for heating a cabin 12 by absorbing heat from a motor 11 comprises: a refrigeration cycle circuit 30 which circulates a coolant to a chiller 35 that absorbs heat from the motor 11, a water-cooled condenser 32 that exhausts heat in order to heat the air sent to the cabin 12 in the time of heating and an evaporator 33 that cools the air sent to the cabin 12 in the time of cooling; and an inside/outside air switching door 22 which switches inside air circulation and outside air introduction of the air sent to the cabin 12. The inside/outside air switching door 22 does not perform heating and dehumidifying by preventing the coolant from being circulated to the evaporator 33 in a case where heating is performed, an outside air temperature is equal to or less than a set outside air temperature, a temperature of the evaporator 33 is equal to or less than a set evaporator temperature and an endothermic quantity from the motor 11 is equal to or greater than a prescribed endothermic quantity.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a vehicle air conditioner that absorbs heat from a heating element and uses it to heat a vehicle interior.

In a vehicle air conditioner, heat may be absorbed from a heat generating element such as a motor, battery, or engine and used to heat the vehicle interior. The vehicle air conditioner has a chiller that absorbs heat from a heating element, a heat exchanger that exhausts heat to heat the air that is blown into the passenger compartment during heating, and an evaporator that cools the air that is blown into the passenger compartment during cooling. It has a refrigeration cycle circuit that circulates refrigerant. For example, Patent Document 1 discloses a vehicle air conditioner that absorbs heat from a motor using a chiller and uses exhaust heat to heat a vehicle interior.

Japanese Patent Application Publication No. 2022-053319

In the vehicle air conditioner described above, when outside air is introduced at extremely low temperatures during heating, the introduced outside air cools the evaporator provided in the air passage, and the pressure of the evaporator decreases. On the other hand, the pressure of a chiller increases due to heat absorption. Therefore, the chiller pressure becomes higher than the evaporator pressure, and refrigerant stagnation occurs in the evaporator. Refrigerant stagnation is a phenomenon in which liquid refrigerant stagnates. When refrigerant stagnation occurs in the evaporator, the amount of refrigerant circulated becomes insufficient and the discharge temperature of the compressor increases.

In order to solve the above problem, an increase in the discharge temperature of the compressor is avoided by limiting the amount of refrigerant circulated to the chiller and lowering the chiller pressure. However, since the amount of heat absorbed by the chiller is limited, the heating capacity will be reduced. Furthermore, if a heating and dehumidifying operation is performed in which refrigerant is circulated through the evaporator in this state, the amount of refrigerant circulated in the chiller is further reduced, and the heating capacity is further reduced.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vehicle air conditioner that can suppress a decrease in heating capacity.

The vehicle air conditioner according to the present invention is a vehicle air conditioner that absorbs heat from a heating element and uses it to heat a vehicle interior, and includes a chiller that absorbs heat from the heat generator and heats air blown into the vehicle interior during heating. It is equipped with a refrigeration cycle circuit that circulates refrigerant between a heat exchanger that exhausts heat for heating, an evaporator that cools the air blown into the passenger compartment during heating and dehumidification, and a refrigeration cycle circuit that circulates refrigerant between the In addition, when the temperature of the evaporator is below the set evaporator temperature and the amount of heat absorbed from the heating element is above the set amount of heat absorbed, heating and dehumidification are not performed by not circulating the refrigerant to the evaporator.

With the above configuration, it is possible to increase the amount of heat absorbed by the chiller and suppress a decrease in heating capacity.

In the vehicle air conditioner according to the present invention, it is preferable to calculate the amount of heat absorbed from the heating element based on the rotation speed of the compressor of the refrigeration cycle, the output of the heating element, or the inlet water temperature of the chiller.

With the above configuration, the amount of heat absorbed by the chiller can be calculated using an existing sensor or the like.

In the vehicle air conditioner according to the present invention, when the outside air temperature is decreasing, the set outside air temperature is set as the first set outside air temperature, and when the outside air temperature is rising, the set outside air temperature is set as the first set outside air temperature. It is preferable to set the second set outside air temperature to a higher value.

With the above configuration, it is possible to avoid unstable switching between normal control and heating/dehumidification prohibition control.

In the vehicle air conditioner according to the present invention, when the evaporator temperature is decreasing, the set evaporator temperature is set as the first set evaporator temperature, and when the set evaporator temperature is rising, the set evaporator temperature is set as the first set evaporator temperature. It is preferable to set the second set evaporator temperature higher than the temperature.

With the above configuration, it is possible to avoid unstable switching between normal control and heating/dehumidification prohibition control.

In the vehicle air conditioner according to the present invention, when the heat absorption amount is increasing, the set heat absorption amount is set as the first setting heat absorption amount, and when the heat absorption amount is decreasing, the heat absorption amount is set as the first setting heat absorption amount. It is preferable to set the second set heat absorption amount to a low value.

With the above configuration, it is possible to prevent switching between normal control and heating/dehumidification prohibition control from becoming unstable.

According to the vehicle air conditioner of the present invention, it is possible to increase the heat absorption amount of the chiller and suppress a decrease in heating capacity.

FIG. 1 is a schematic diagram showing a vehicle air conditioner that is an example of an embodiment. FIG. 1 is a block diagram showing a vehicle air conditioner that is an example of an embodiment. FIG. 3 is a diagram illustrating a set outside air temperature. It is a figure explaining setting evaporator temperature. FIG. 3 is a diagram illustrating a set amount of heat absorption. It is a flow chart which shows the flow of heating dehumidification prohibition control.

Hereinafter, an example of an embodiment of the present invention will be described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are illustrative to facilitate understanding of the present invention, and can be changed as appropriate depending on the use, purpose, specifications, etc.
<Vehicle air conditioning system>
An air conditioner 10, which is an example of an embodiment, will be described using FIGS. 1 and 2.

In the air conditioner 10 as a vehicle air conditioner, heat is absorbed from the motor 11 as a heating element and used for heating the vehicle interior 12 . The air conditioner 10 includes a chiller 35 that absorbs heat from the motor 11 via a motor cooling circuit 50, a water-cooled condenser 32 that serves as a heat exchanger that exhausts heat to heat the air blown into the passenger compartment 12 during heating, and a water-cooled condenser 32 that absorbs heat from the motor 11 through the motor cooling circuit 50. It has an evaporator 33 that cools the air blown into the vehicle compartment 12, and a refrigeration cycle circuit 30 that circulates a refrigerant. According to the air conditioner 10, although details will be described later, it is possible to suppress a decrease in heating capacity.

Air conditioner 10 is mounted on a vehicle. The vehicle is a four-wheel electric vehicle, and is driven by a motor 11 driven by battery power. However, the vehicle is not limited to an electric vehicle, and may be a hybrid vehicle, for example.

The heating element of this embodiment is the motor 11, which is cooled by a motor cooling circuit 50, which will be described in detail later. The heating element is not limited to the motor 11, but may be a battery or, in the case of a hybrid vehicle, an engine.

As shown in FIG. 1, the air conditioner 10 includes an air passage 20 for blowing conditioned air into the vehicle interior 12, the above-mentioned refrigeration cycle circuit 30, and a heater circuit that heats the air blown by the air passage 20. 40, a motor cooling circuit 50 that cools the motor 11, and an air conditioning ECU (Electronic Control Unit) 60 that controls each device of the air passage 20, the refrigeration cycle circuit 30, the heater circuit 40, and the motor cooling circuit 50. ing.

The air passage 20 is a passage that conditions air and blows the conditioned air into the vehicle interior 12. The air passage 20 includes a heater core 41 that is connected to the heater circuit 40 and heats the air passing through the air passage 20, an evaporator 33 that is connected to the refrigeration cycle circuit 30 and cools the air that passes through the air passage 20, and a vehicle interior. The internal/external air switching door 22 switches between internal air circulation or external air introduction of the air blown to the vehicle compartment 12, and the air mix door 23 switches between the air being blown to the heater core 41 or the evaporator 33. It has a blower 24.

The refrigeration cycle circuit 30 includes a compressor 31 that compresses refrigerant, a water-cooled condenser 32 that is connected to the heater circuit 40 and serves as a heat exchanger that exhausts heat to the cooling water circulating through the heater circuit 40, and is provided in the air passage 20. , an evaporator 33 that cools the air passing through the air passage 20 , an evaporator-side expansion valve 34 that adjusts the amount of refrigerant circulating to the evaporator 33 , and a motor cooling circuit 50 that is connected to the cooling water that circulates through the motor cooling circuit 50 . A chiller 35 that absorbs heat and a chiller-side expansion valve 36 that adjusts the amount of refrigerant circulating to the chiller 35 are connected by piping. Further, the evaporator 33 is provided with an evaporator temperature sensor 64 that detects the temperature of the evaporator 33.

In this embodiment, the water-cooled condenser 32 is used as the heat exchanger for discharging heat for use in heating, but the present invention is not limited thereto. A configuration may be adopted in which the heat exchanger is used as a heater core and the exhaust heat from the refrigerant is directly utilized for heating without providing the heater circuit 40.

The heater circuit 40 achieves heating operation by circulating water heated by the water cooling condenser 32 as a heat source and heating the air passing through the air passage 20 by the heater core 41. The heater circuit 40 includes a water-cooled condenser 32 that heats water circulating through the heater circuit 40, a heater core 41 provided in the air passage 20 that heats the air passing through the air passage 20, and a heater core 41 that circulates the cooling water of the heater circuit 40. It has a pump 42.

The motor cooling circuit 50 cools the motor 11 by circulating cooling water cooled by the chiller 35. The motor cooling circuit 50 includes a chiller 35 that cools the cooling water circulating in the motor cooling circuit 50, a radiator 51 that cools the cooling water circulating in the motor cooling circuit 50, a motor cooler 52 that cools the motor 11, and a motor cooler 52 that cools the motor 11. It has a pump 53 that circulates the cooling water of the cooling circuit 50. Furthermore, a cooling water temperature sensor 65 is provided at the inlet of the chiller 35 to detect the temperature of the cooling water circulating in the motor cooling circuit 50.

The air conditioning ECU 60 controls the air passage 20, the refrigeration cycle circuit 30, the heater circuit 40, and the motor cooling circuit 50, respectively. The air conditioning ECU 60 executes heating dehumidification prohibition control, which will be described in detail later, in the air conditioner 10. The air conditioning ECU 60 is a computer that includes a processor 61 that has a CPU that processes information therein, and a memory 62 that stores software, programs, or data that the processor 61 executes.

The air conditioning ECU 60 controls the internal/external air switching door 22 , the air mix door 23 , and the blower 24 of the air passage 20 , the compressor 31 of the refrigeration cycle circuit 30 , the evaporator-side expansion valve 34 and the chiller-side expansion valve 36 , and the pump of the heater circuit 40 . 42 and the pump 53 of the motor cooling circuit 50. The air conditioning ECU 60 also includes an outside air temperature sensor 63 that detects the outside air temperature, an evaporator temperature sensor 64 that detects the temperature of the evaporator 33, and a cooling water temperature sensor that detects the temperature of the cooling water at the inlet of the chiller 35 of the motor cooling circuit 50. It is connected to sensor 65.

As shown in FIG. 2, the air conditioning ECU 60 includes a heating operation execution unit 71, an outside air temperature determination unit 72, an evaporator temperature determination unit 73, a chiller heat absorption amount determination unit 74, and a chiller heat absorption limiting unit, each of which will be described in detail later. 75, and a heating/dehumidifying operation prohibition section 76. The heating operation execution section 71, the outside air temperature determination section 72, the evaporator temperature determination section 73, the chiller heat absorption amount determination section 74, the chiller heat absorption restriction section 75, and the heating dehumidification operation prohibition section 76 are configured so that the processor 61 executes the program stored in the memory 62. This is achieved by executing.

The heating operation execution unit 71 executes a heating operation in which heat is absorbed from the motor 11 and used for heating the vehicle interior 12 . Specifically, in the refrigeration cycle circuit 30, the rotation speed of the compressor 31 is controlled to circulate the refrigerant, and the opening degree of the chiller-side expansion valve 36 is adjusted to evaporate the refrigerant in the chiller 35, thereby controlling the motor cooling circuit. The refrigerant absorbs heat from the cooling water 50 and condenses the refrigerant in the water cooling condenser 32, thereby discharging the heat to the circulating water of the heater circuit 40.

The heating operation execution unit 71 also drives the pump 42 in the heater circuit 40 to circulate circulating water, heats the heater core 41 with the exhaust heat of the water-cooled condenser 32, and heats the air passing through the air passage 20. . Further, in the motor cooling circuit 50, the pump 53 is driven to circulate cooling water, and the motor cooler 52 is cooled by heat absorption by the chiller 35 and heat absorption by the radiator 51.

The outside air temperature determination unit 72 detects the outside air temperature from the outside air temperature sensor 63, and determines whether the outside air temperature is equal to or lower than the set outside air temperature.

As shown in FIG. 3, the outside air temperature determining unit 72 sets the set outside air temperature to the first set outside air temperature To1 when the outside air temperature To is decreasing, and sets the set outside air temperature to the first set outside air temperature To1 when the outside air temperature To is rising. The temperature is set to a second set outside air temperature To2 higher than the first set outside air temperature Tol. Thereby, it is possible to avoid instability in switching between normal control and heating/dehumidification prohibition control, which will be described later.

The evaporator temperature determination section 73 detects the evaporator temperature from the evaporator temperature sensor 64 and determines whether the evaporator 33 is at or below the set evaporator temperature.

As shown in FIG. 4, the evaporator temperature determination unit 73 sets the set evaporator temperature to the first set evaporator temperature Te1 when the evaporator temperature Te is decreasing, and sets the set evaporator temperature to the first set evaporator temperature Te1 when the evaporator temperature Te is increasing. The temperature is set to a second set evaporator temperature Te2 higher than the first set evaporator temperature Te1. Thereby, it is possible to avoid instability in switching between normal control and heating/dehumidification prohibition control, which will be described later.

The chiller heat absorption amount determining unit 74 calculates the heat absorption amount of the chiller 35, and determines whether the heat absorption amount of the chiller 35 is equal to or greater than a set heat absorption amount. In this embodiment, the amount of heat absorbed by the chiller 35 is calculated based on the temperature of the cooling water at the inlet of the chiller 35 of the motor cooling circuit 50 detected by the cooling water temperature sensor 65.

The chiller heat absorption amount determination unit 74 may calculate the heat absorption amount of the chiller 35 by estimating the motor cooling load based on the rotation speed of the compressor 31, or may estimate the motor cooling load based on the output of the motor 11. The amount of heat absorbed by the chiller 35 may be calculated. Thereby, the amount of heat absorbed by the chiller 35 can be calculated using an existing sensor or the like.

As shown in FIG. 5, when the chiller heat absorption amount Qc is increasing, the chiller heat absorption amount determining unit 74 sets the set chiller heat absorption amount to the first setting chiller heat absorption amount Qc1, and the chiller heat absorption amount Qc is decreasing. In this case, the set chiller heat absorption amount is set to the second set chiller heat absorption amount Qc2, which is lower than the first set chiller heat absorption amount Qc1. Thereby, it is possible to avoid instability in switching between normal control and heating/dehumidification prohibition control, which will be described later.

When a pressure difference occurs between the evaporator 33 and the chiller 35, the chiller heat absorption limiting section 75 limits the amount of heat absorbed by the chiller 35 by adjusting the chiller-side expansion valve 36 to limit the amount of refrigerant circulating in the chiller 35. However, the low pressure of the refrigeration cycle circuit 30 is lowered to avoid an increase in the discharge temperature of the compressor 31. The pressure difference between the evaporator 33 and the chiller 35 may be calculated using the evaporator temperature sensor 64 and a temperature sensor provided on the refrigerant side of the chiller 35.

The heating and dehumidifying operation prohibition section 76 prohibits the dehumidifying operation while the heating operation execution section 71 is executing the heating operation. Here, in the dehumidifying operation, while the heating operation execution unit 71 is executing the heating operation, the evaporator-side expansion valve 34 is opened to circulate the refrigerant through the evaporator 33 to cool the air blown into the vehicle compartment 12. .

The heating/dehumidifying operation prohibition unit 76 is configured to operate when the heating operation is executed and the outside air temperature at which the cold air is introduced to cool the evaporator 33 is below the set outside air temperature, and the temperature of the evaporator 33 is below the set evaporator temperature. This is a case where the amount of heat absorbed by the chiller 35 is greater than or equal to the set amount of heat absorbed, and it is assumed that a pressure difference between the evaporator 33 and the chiller 35 occurs and the refrigerant is trapped in the evaporator 33. Since the amount of refrigerant circulated is limited and the heating capacity is reduced, the evaporator-side expansion valve 34 is closed to prohibit dehumidifying operation.

According to the heating and dehumidifying operation prohibition unit 76, by closing the evaporator-side expansion valve 34 and increasing the amount of refrigerant circulation in the chiller 35 to increase the amount of heat absorbed by the chiller 35, it is possible to suppress a decrease in heating capacity. .

<Heating dehumidification operation prohibition control>
The flow of the heating/dehumidifying operation prohibition control will be explained using FIG. 6 .

In step S<b>11 , it is determined whether the heating operation execution unit 71 is executing a heating operation in which heat is absorbed from the motor 11 and used to heat the vehicle interior 12 . If the heating operation is being executed, the process moves to step S12.

In step S12, the outside air temperature determination unit 72 determines whether the outside air temperature is equal to or lower than the set outside air temperature. If the outside air temperature is below the set outside air temperature, the process moves to step S13.

In step S13, the evaporator temperature determining section 73 determines whether the temperature of the evaporator 33 is equal to or lower than the set evaporator temperature. If the temperature of the evaporator 33 is equal to or lower than the set evaporator temperature, the process moves to step S14.

In step S14, the chiller heat absorption amount determination unit 74 determines whether the heat absorption amount of the chiller 35 is equal to or greater than the set heat absorption amount. If the amount of heat absorbed by the chiller 35 is greater than or equal to the set amount of heat absorbed, the process moves to step S15.

In step S15, the heating/dehumidifying operation prohibition unit 76 executes a heating operation in which heat is absorbed from the motor 11 and used for heating the passenger compartment 12, and cold air is introduced into the outside air to cool the evaporator 33. When the temperature is below a predetermined temperature and the temperature of the evaporator 33 is below a predetermined temperature, a pressure difference between the evaporator 33 and the chiller 35 is generated and the amount of heat absorbed by the chiller 35 is assumed to be stagnation in the evaporator 33. If it exceeds the amount of heat, the amount of refrigerant circulated in the chiller 35 is limited and the heating capacity is reduced, so the heating and dehumidifying operation is prohibited to suppress the reduction in the heating capacity.

<Summary>
In the air conditioner 10 of this embodiment, when outside air is introduced at extremely low temperatures during heating, the evaporator 33 provided in the air passage 20 is cooled by the introduced outside air, and the pressure of the evaporator 33 is reduced. On the other hand, the pressure of the chiller 35 increases due to heat absorption. Therefore, the chiller pressure becomes higher than the evaporator pressure, refrigerant stagnation occurs in the evaporator 33, the amount of refrigerant circulation becomes insufficient, and the discharge temperature of the compressor 31 increases.

Therefore, by limiting the amount of refrigerant circulating to the chiller 35 and lowering the chiller pressure, an increase in the discharge temperature of the compressor 31 is avoided. However, since the amount of heat absorbed by the chiller is limited, the heating capacity will be reduced. Furthermore, if a heating and dehumidifying operation is performed in which refrigerant is circulated through the evaporator 33 in this state, the amount of refrigerant circulated in the chiller 35 is further reduced, and the heating capacity is further reduced.

Therefore, the air conditioner 10 of this embodiment is an air conditioner 10 that absorbs heat from the motor 11 and uses it for heating the vehicle interior 12. A refrigeration cycle circuit 30 is provided that circulates refrigerant through a water-cooled condenser 32 that exhausts heat to heat the vehicle, an evaporator 33 that cools the air blown into the passenger compartment 12 during heating and dehumidification, and a refrigeration cycle circuit 30 that circulates refrigerant between is below the set outside air temperature, the temperature of the evaporator 33 is below the set evaporator temperature, and the amount of heat absorbed from the motor 11 is above the set amount of heat absorbed, the amount of refrigerant circulated in the chiller 35 is limited and the heating capacity is reduced. Therefore, heating and dehumidification are not performed by not circulating refrigerant to the evaporator 33.

Thereby, by increasing the amount of refrigerant circulating in the chiller 35 and increasing the amount of heat absorbed by the chiller 35, it is possible to suppress a decrease in the heating capacity.

It should be noted that the present invention is not limited to the above-described embodiments and modifications thereof, and it goes without saying that various changes and improvements can be made within the scope of the claims of the present application. .

10 air conditioner (vehicle air conditioner), 11 motor (heating element), 12 vehicle interior, 20 air passage, 22 inside/outside air switching door (switching part), 23 air mix door, 24 blower, 30 refrigeration cycle circuit, 31 compression machine, 32 water-cooled condenser (heat exchanger), 33 evaporator, 34 evaporator side expansion valve, 35 chiller, 36 chiller side expansion valve, 40 heater circuit, 41 heater core, 42 pump, 50 motor cooling circuit, 51 radiator, 52 motor cooling device, 53 pump, 60 air conditioning ECU, 61 processor, 62 memory, 63 outside air temperature sensor, 64 evaporator temperature sensor, 65 cooling water temperature sensor, 71 heating operation execution unit, 72 outside air temperature determination unit, 73 evaporator temperature determination unit, 74 Chiller heat absorption amount determination section, 75 Chiller heat absorption limit section, 76 Heating dehumidification operation prohibition section

Claims (5)

A vehicle air conditioner that absorbs heat from a heating element and uses it to heat a vehicle interior,
A refrigerant is supplied to a chiller that absorbs heat from the heating element, a heat exchanger that exhausts heat to heat the air blown to the passenger compartment during heating, and an evaporator that cools the air blown to the passenger compartment during heating and dehumidification. Equipped with a refrigeration cycle circuit that circulates
During heating, when the outside air temperature is below the set outside air temperature, the temperature of the evaporator is below the set evaporator temperature, and the amount of heat absorbed from the heating element is more than the set amount of heat absorbed, refrigerant is supplied to the evaporator. By not circulating, heating and dehumidifying are not performed.
Vehicle air conditioning system. The vehicle air conditioner according to claim 1,
Calculating the amount of heat absorbed from the heating element based on the rotation speed of the compressor of the refrigeration cycle circuit, the output of the heating element, or the inlet water temperature of the chiller;
Vehicle air conditioning system. The vehicle air conditioner according to claim 1 or 2,
When the outside air temperature is decreasing, the set outside air temperature is set as the first set outside air temperature, and when the outside air temperature is rising, the set outside air temperature is set as the second set outside air temperature, which is higher than the first set outside air temperature. and
Vehicle air conditioning system. The vehicle air conditioner according to claim 1 or 2,
When the evaporator temperature is decreasing, the set evaporator temperature is set as the first set evaporator temperature, and when the evaporator temperature is rising, the set evaporator temperature is set as the second set evaporator temperature higher than the first set evaporator temperature. and
Vehicle air conditioning system. The vehicle air conditioner according to claim 1 or 2,
When the amount of heat absorption is rising, the set heat absorption amount is set as the first set heat absorption amount, and when the heat absorption amount is decreasing, the heat absorption amount is set as the second set heat absorption amount, which is lower than the first set heat absorption amount. do,
Vehicle air conditioning system.

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