JP2024068822A - Vehicle air conditioning system - Google Patents

Abstract

[Problem] In a vehicle air conditioner, when operating in a bi-level mode during dehumidification heating, the temperature difference between cold air and hot air is made clear. [Solution] When both front and rear air conditioning units 28F, 28R are operating under conditions in which an air conditioner 26 performs dehumidification heating, if a bi-level mode is selected in which cold air is sent to the upper body of an occupant and hot air is sent to the feet, a refrigeration cycle circuit 30 performs cooling operation and a heating circuit 32 generates high-temperature liquid. The cooling operation of the refrigeration cycle circuit 30 supplies liquid-phase refrigerant to front and rear evaporators 42F, 42R, and the air is strongly cooled. A portion of the cooled air is blown toward the upper body of the occupant. The remainder of the cooled air is warmed by high-temperature liquid supplied to front and rear heater cores 44F, 44R, and is blown toward the feet. [Selected Figure] FIG. 1

Description

The present invention relates to a vehicle air conditioning device that provides air conditioning for the passenger compartment of a vehicle.

The following Patent Document 1 discloses an air conditioner for vehicles that uses a refrigeration cycle to dehumidify and heat the passenger compartment of a vehicle. An evaporator (2) and a radiator (4) are arranged inside an air conditioner casing (1), which serves as a passage for air sent to the passenger compartment. When performing dehumidification and heating, a refrigerant compressed by a compressor (7) and heated to a high temperature is sent to the radiator (4). The refrigerant is sent from the radiator (4) to an exterior heat exchanger (8) where it is cooled, and is then sent to the evaporator (2). Inside the air conditioner casing (1), the air is cooled by the evaporator (2), and the water vapor in the air condenses. The dehumidified and cooled air is warmed by the radiator (4), and the dehumidified warm air is blown into the passenger compartment.

There is also a known vehicle air conditioning system that has separate air conditioning units for conditioning the front space of the passenger compartment and the rear space. There is also a known vehicle air conditioning system that has a so-called bi-level mode that blows cool air toward the upper bodies of passengers and warm air toward the feet.

The reference symbols in parentheses above are those used in the following Patent Document 1, and are not related to the reference symbols used in the description of the embodiments of this application.

JP 2004-142506 A

When a vehicle air conditioning system operates in bi-level mode, it is necessary to clearly define the temperature difference between the cold air directed toward the upper bodies of occupants and the warm air directed toward the feet. In dehumidifying and heating operation, it can be difficult to create a sufficient temperature difference between the cold air and the warm air. Furthermore, in dehumidifying and heating operation, if the refrigerant sent to the air conditioning unit is in a two-phase gas-liquid state, it may not be possible to properly distribute the refrigerant supplied to the front and rear air conditioning units. An air conditioning unit with a shortage of refrigerant may not be able to sufficiently lower the temperature of the cold air.

The present invention ensures that when both the front and rear air conditioning units operate under conditions for dehumidification operation and at least one of the air conditioning units performs bi-level operation, cool air and hot air at appropriate temperatures are blown out from the air conditioning units.

The vehicle air conditioning device according to the present invention includes a front air conditioning unit that conditions the air in the front space of the vehicle passenger compartment, a rear air conditioning unit that conditions the air in the rear space of the vehicle passenger compartment, a refrigeration cycle circuit that supplies refrigerant to the front air conditioning unit and the rear air conditioning unit, and a heating circuit that generates high-temperature liquid using the refrigerant from a heat source or the refrigeration cycle circuit and supplies the high-temperature liquid to the front air conditioning unit and the rear air conditioning unit. The dehumidification and heating operation range is defined by the required blowing temperature, which is the control target for the temperature of the air sent out from the front air conditioning unit and the rear air conditioning unit, and the outside air temperature. In the dehumidifying and heating operation range, when the front and rear air conditioning units are in operation and at least one of the front and rear air conditioning units is performing bi-level operation to blow cool air to the upper bodies of occupants and warm air to the feet, the refrigeration cycle circuit performs cooling operation and supplies refrigerant to the front and rear air conditioning units, and the heating circuit generates high-temperature liquid using a heat source and supplies it to the front and rear air conditioning units.

By operating the refrigeration cycle circuit in cooling mode, the refrigerant is only in liquid phase. This allows the liquid phase refrigerant to be appropriately distributed to the front and rear air conditioning units, and sufficiently cooled air is generated in the front and rear air conditioning units. In addition, warm air is generated in the front and rear air conditioning units by the heating circuit.

In the above vehicle air conditioning system, the heat source of the heating circuit can be one or both of the engine that drives the vehicle and an electric heater.

The front and rear air conditioning units generate sufficiently cold air and sufficiently warm air, so there is a clear temperature difference between the cold air blown toward the occupants' upper bodies and the warm air blown toward their feet.

1 is a diagram showing a schematic configuration of a vehicle equipped with a thermal management system including a vehicle air conditioning device of the present embodiment. FIG. 2 is a diagram showing a front air conditioning unit and its control unit. 1 is a diagram illustrating a schematic configuration of a thermal management system according to an embodiment of the present invention; FIG. 4 is a diagram showing conditions that define operation modes of the air conditioning apparatus. FIG. 2 is a diagram showing the operation state of the thermal management system, particularly during heating operation using engine coolant. FIG. 2 is a diagram showing the operating state of the thermal management system, particularly during heating operation using an electric heater. FIG. 2 is a diagram showing an operating state of the thermal management system, particularly showing a state during heating operation by a heat pump operation of a refrigeration cycle circuit. FIG. 2 is a diagram showing the operating state of the thermal management system, particularly during cooling operation. FIG. 2 is a diagram showing the operating state of the thermal management system, particularly during parallel dehumidification and heating operation. FIG. 2 is a diagram showing the operation state of the thermal management system, particularly during serial dehumidification and heating operation. FIG. 2 is a diagram showing the operating state of the thermal management system, particularly in the dehumidifying and heating area, in which the front and rear air conditioning units are operating and at least one of them is in bi-level operation. FIG. 2 is a diagram showing a portion of a control flow of the thermal management system.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the general configuration of a thermal management system 12 of a vehicle 10. The vehicle 10 is equipped with an engine 14 and two electric motors 16F, 16R that drive the front and rear wheels, respectively, as prime movers for driving the vehicle 10. The vehicle 10 is equipped with a battery 18 that supplies power to the electric motors 16F, 16R and is charged with power generated by the electric motors 16F, 16R during braking. The vehicle may be equipped with one electric motor that drives only the front wheels or the rear wheels. Furthermore, the vehicle may be equipped with no engine and drive one or both of the front and rear wheels with an electric motor. Hereinafter, for simplicity, the electric motors 16F, 16R will be simply referred to as motors 16.

The thermal management system 12 cools the engine 14, the motor 16, and the battery 18, and also air-conditions the passenger compartment 20. The cooling system for the engine 14 includes an engine radiator 22 that dissipates heat generated by the engine through engine coolant. The engine coolant flows through a pipe connecting the engine 14 and the engine radiator 22 and circulates between the engine 14 and the engine radiator 22. In FIG. 1, the pipe connecting the engine 14 and the engine radiator 22 is omitted. The cooling system for the motor 16 includes a motor radiator 24 that dissipates heat generated by the motor 16 through motor coolant. The motor coolant flows through a pipe connecting the motor 16 and the motor radiator 24 and circulates between the motor 16 and the motor radiator 24. In FIG. 1, the pipe connecting the motor 16 and the motor radiator 24 is omitted.

The thermal management system 12 includes an air conditioner 26 that conditions the passenger compartment 20. The air conditioner 26 has an air conditioning unit 28 that supplies air with regulated temperature, humidity, etc. to the passenger compartment 20. The air conditioning unit 28 includes a front air conditioning unit 28F that conditions the space on the front seat side of the passenger compartment 20 and a rear air conditioning unit 28R that conditions the space on the rear seat side. The air conditioner 26 includes a refrigeration cycle circuit 30 that sends refrigerant to the air conditioning unit 28, and a heating circuit 32 that sends heated liquid. The refrigeration cycle circuit 30 includes a compressor 34 that compresses the refrigerant, and an outdoor condenser 36 that cools the refrigerant compressed by the compressor 34 with outside air to liquefy it. The compressor 34 may be an electric compressor driven by an electric motor, and the output of the compressor 34 can be adjusted by controlling the rotation speed of the electric motor. The heating circuit 32 includes an electric heater 38 as a heat source. The refrigeration cycle circuit 30 and the heating circuit 32 will be described in more detail later, along with the other cooling systems of the thermal management system 12.

The thermal management system 12 further includes a battery cooling circuit 40 that cools the battery 18. The battery cooling circuit 40 cools the battery 18 by supplying battery coolant cooled by the refrigerant of the refrigeration cycle circuit 30 in a battery cooling heat exchanger 41 to the battery 18.

2 is a diagram showing a schematic configuration of the front air conditioning unit 28F. The front air conditioning unit 28F has a front evaporator 42F, which is one of the components of the refrigeration cycle circuit 30, and a front heater core 44F, which is one of the components of the heating circuit 32, and further has an air conditioning case 46 that houses the front evaporator 42F and the front heater core 44F. The air conditioning case 46 has an air inlet 48 that introduces air into the air conditioning case 46. The air inlet 48 includes an inside air inlet 48C that introduces air from inside the passenger compartment 20 and an outside air inlet 48E that introduces air from outside the vehicle. The air conditioning case 46 also has an air outlet 50 that sends out the conditioned air toward a predetermined location. The air outlet 50 includes a head outlet 50H for blowing air toward the upper body of the front seat occupant, i.e., the head and its surroundings, a foot outlet 50F for blowing air toward the feet of the front seat occupant, and a defroster outlet 50D for blowing air toward the interior surface of the windshield. The airflow blown out from the head outlet 50H passes through a duct in the instrument panel (not shown) and is blown out from a plurality of outlets formed in the instrument panel to the head and its surroundings of the front seat occupant in the passenger compartment 20. The airflow blown out from the foot outlet 50F is blown out directly from the foot outlet 50F or through a duct in the instrument panel to the feet of the front seat occupant. The airflow blown out from the defroster outlet 50D passes through a duct in the instrument panel and is blown out from an outlet provided opposite to the lower edge of the windshield. The front air conditioning unit 28F has a blower 52 arranged upstream of the air conditioning case 46. The blower 52 generates an airflow that flows from the air inlet 48 to the air outlet 50.

An inside/outside air switching door 54 is disposed at the confluence of the flow path from the inside air inlet 48C and the flow path from the outside air inlet 48E. The inside/outside air switching door 54 can rotate between a position that closes the inside air inlet 48C and a position that closes the outside air inlet 48E, and the mixing ratio of the inside air and the outside air is adjusted according to the rotation angle. An air mix door 56 is disposed between the front evaporator 42F and the front heater core 44F. The air mix door 56 rotates to adjust the amount of air that passes through the front heater core 44F out of the air that has passed through the front evaporator 42F. A delivery door 58 that opens and closes the air delivery port 50 is provided corresponding to each air delivery port 50. Specifically, the head outlet 50H is provided with a head outlet door 58H, the foot outlet 50F is provided with a foot outlet door 58F, and the defroster outlet 50D is provided with a defroster outlet door 58D, and the amount of air blown from each outlet 50 is adjusted by the opening degree of each outlet door 58.

The controller 60 controls the volume of air sent by the blower 52, the rotation angle of the inside/outside air switching door 54 and the air mix door 56, and the opening of each outlet door 58. The controller 60 controls the rotation angle of the inside/outside air switching door 54 and the air mix door 56, the opening of each outlet door 58, and the volume of air sent by the blower 52 based on the conditions set by the occupant and the environmental conditions. The occupant sets the desired temperature using the temperature setting switch 62, and further sets the air outlet 50 from which the occupant wishes to send air using the outlet changeover switch 64. The air outlet 50 can be selected in a blowing mode in which one of the air outlets 50H, 50F, and 50D is selected individually, or in a blowing mode in which air is sent from both the head outlet 50H and the foot outlet 50F. The occupant can also set the automatic air conditioning mode using the automatic air conditioning switch 66. In this case, the controller 60 selects the air outlet 50 from which the occupant will send air according to a predetermined program in accordance with the desired temperature and the environmental conditions. The control unit 60 receives inputs of the air temperature in the passenger compartment 20 detected by a room temperature sensor 68, the outside air temperature detected by an outside air temperature sensor 70, the liquid temperature in the heating circuit 32 detected by a liquid temperature sensor 72, and the amount of solar radiation entering the passenger compartment 20 detected by a solar radiation sensor 74. In addition, the control unit 60 receives inputs of the temperature of the air immediately after passing through the front evaporator 42F (evaporator outlet temperature) detected by an evaporator outlet temperature sensor 76 disposed immediately after the front evaporator 42F.

The air conditioning device 26 can operate in a so-called bi-level mode (hereinafter referred to as bi-level operation) in which cool air is directed toward the upper body of the front seat occupant and warm air is directed toward the feet. The bi-level operation is performed, for example, by the occupant operating the bi-level switch 65 provided on the air outlet changeover switch 64. In the bi-level operation, the control unit 60 controls the air mix door 56 and each outlet door 58 of the front air conditioning unit 28F to form a predetermined air flow. With regard to the outlet doors 58, the head outlet door 58H and the foot outlet door 58F are opened. The air taken into the air conditioning case 46 by the blower 52 is blown out from the head outlet 50H and the foot outlet 50F, and is blown out toward the upper body and the feet of the occupant, respectively. In addition, the air mix door 56 is positioned to guide a part of the air sent by the blower 52 to the front heater core 44F and the remainder to bypass the front heater core 44F. In the bi-level operation, the refrigerant is supplied to the front evaporator 42F by the refrigeration cycle circuit 30, where it is vaporized and absorbs heat from the air passing through the front evaporator 42F. Thus, the air passing through the front evaporator 42F is cooled, and the water vapor in the air is condensed to dehumidify the air. In addition, the heating circuit 32 sends high-temperature liquid to the front heater core 44F, and the air passing through the front heater core 44F is warmed. In other words, the air once cooled by the front evaporator 42F is warmed by the front heater core 44F and becomes dry and warm air. The air passing through the front heater core 44F is led to the foot outlet 50F and discharged from there. On the other hand, the air that bypasses the front heater core 44F is led to the head outlet 50H while still cold, and is discharged from there. An air guide plate (not shown) may be installed inside the air conditioning case 46 to guide the hot air that has passed through the front heater core 44F to the foot outlet 50F and the bypassed cold air to the head outlet 50H.

The rear air conditioning unit 28R has a configuration similar to that of the front air conditioning unit 28F and is not shown in the figures. The rear air conditioning unit 28R has an air conditioning case that houses the rear evaporator 42R and the rear heater core 44R (see FIG. 1), and the air conditioning case is provided with an air inlet and an air outlet. In the rear air conditioning unit 28R, the air inlet does not need to include an outside air inlet, and the air outlet does not need to include a defroster outlet. The rear air conditioning unit 28R, like the front air conditioning unit 28F, can send conditioned air to the upper bodies and feet of rear seat occupants.

The rear air conditioning unit 28R can be switched on and off by the passenger. When the passenger operates the rear air conditioning switch 67, the control unit 60 operates the rear air conditioning unit 28R in addition to the front air conditioning unit 28F. The front air conditioning unit 28F and the rear air conditioning unit 28R can be set to different temperatures and have their air outlet modes selected independently. The rear air conditioning unit 28R can also perform bi-level operation in conjunction with the front air conditioning unit 28F or independently.

The control unit 60 is a processing device that controls the air conditioning device 26 according to a predetermined program and operates to achieve the temperature and airflow mode desired by the occupants according to the above temperatures, amount of solar radiation, etc.

Figure 3 is a diagram showing a schematic configuration of the thermal management system 12. The same reference numerals are used for the components already described. The refrigeration cycle circuit 30 includes the compressor 34, the outdoor condenser 36, the front and rear evaporators 42F, 42R, and the outdoor condenser 36, as already described, as well as a liquid-cooled condenser 78 that exchanges heat with the heating circuit 32 and a battery cooling heat exchanger 41 that exchanges heat with the battery cooling circuit 40. In the refrigeration cycle circuit 30, electric expansion valves 84, 86 whose opening degree can be adjusted are provided upstream of the front evaporator 42F and the battery cooling heat exchanger 41, respectively, and an expansion valve 88 and an electromagnetic valve 90 are provided upstream of the rear evaporator 42R. The electric expansion valves 84, 86 cannot be completely closed, and even when the opening degree is set to the smallest, a small amount of refrigerant is supplied to the front evaporator 42F and the battery cooling heat exchanger 41. On the other hand, the supply of refrigerant to the rear evaporator 42R can be completely stopped by closing the solenoid valve 90. Furthermore, a heating expansion valve 92 is provided upstream of the outdoor condenser 36. The opening of the heating expansion valve 92 can be adjusted, and it may be an electric expansion valve. When the refrigeration cycle circuit 30 is in heating operation, the refrigerant expands by passing through the heating expansion valve 92 with a small opening, and is vaporized in the outdoor condenser 36 to absorb heat. Therefore, in heating operation, the outdoor condenser 36 functions as an evaporator. When the refrigeration cycle circuit 30 is in cooling operation, the heating expansion valve 92 is fully opened to simply pass the refrigerant. The capacity of the refrigeration cycle circuit 30 is adjusted by adjusting the output of the compressor 34 and the opening of each expansion valve 84, 86, 88, 92.

The refrigeration cycle circuit 30 has a first bypass flow path 94 arranged in parallel to the front and rear evaporators 42F, 42R and the battery cooling heat exchanger 41. The refrigerant can bypass the front and rear evaporators 42F, 42R and the battery cooling heat exchanger 41 by passing through the first bypass flow path 94. The refrigeration cycle circuit 30 also has a second bypass flow path 96 arranged in parallel to the exterior condenser 36, and the refrigerant can bypass the exterior condenser 36 by passing through the second bypass flow path 96.

The battery cooling circuit 40 includes a battery 18, a battery cooling heat exchanger 41, and a battery cooling circuit pump 98 that circulates coolant between the battery 18 and the battery cooling heat exchanger 41. The battery 18 is cooled by sending coolant cooled by the battery cooling heat exchanger 41 to the battery 18. The battery 18 is provided with a battery temperature sensor 100 that detects the temperature of the battery 18. The level of the cooling requirement for the battery 18 is determined based on the temperature of the battery 18, and the battery cooling circuit 40 is controlled according to the level.

The heating circuit 32 includes an electric heater 38, front and rear heater cores 44F, 44R, a liquid-cooled condenser 78, and a heating circuit pump 104 that sends high-temperature liquid. The heating circuit pump 104 circulates the circulating liquid around the electric heater 38, the front and rear heater cores 44F, 44R, and the liquid-cooled condenser 78. The liquid-cooled condenser 78 heats the circulating liquid of the heating circuit 32 with high-temperature refrigerant compressed by the compressor 34 of the refrigeration cycle circuit 30 to generate high-temperature liquid. The high-temperature liquid, which is the circulating liquid heated by the electric heater 38 or the liquid-cooled condenser 78, is sent to the front and rear heater cores 44F, 44R. The heating circuit 32 also shares the heating/cooling liquid with the engine cooling circuit 106, and can use the engine 14 as a heat source. Whether the high-temperature liquid sent to the front and rear heater cores 44F, 44R is supplied from the engine 14 side or from the electric heater 38 and liquid-cooled condenser 78 side is determined by the operation of the three-way valve 108.

The engine cooling circuit 106 includes the engine 14 and the engine radiator 22, and further includes an engine cooling circuit pump 110 that circulates engine coolant between the engine 14 and the engine radiator 22. The engine cooling circuit 106 includes a radiator bypass flow path 112 arranged in parallel with the engine radiator 22, and can circulate the engine coolant by bypassing the engine radiator 22. When the engine 14 is cold, such as during warm-up, the engine cooling circuit 106 does not send the engine coolant to the engine radiator 22, but circulates it through the radiator bypass flow path 112, thereby quickly increasing the temperature of the engine coolant. As described above, the engine coolant can be shared with the circulating liquid of the heating circuit 32.

The flow paths of the refrigerant or liquid in the refrigeration cycle circuit 30, heating circuit 32, battery cooling circuit 40, and engine cooling circuit 106 are changed according to predetermined conditions. The flow paths of the refrigerant or liquid are changed by the operation of the three-way valve 108 and solenoid valve 90 already described, as well as a number of valves (not shown) that are appropriately provided in each circuit. The opening and closing and opening degree of these valves may be controlled by the control unit 60. The control unit 60 also controls the output of the compressor 34, the discharge flow rate of the battery cooling circuit pump 98, and the discharge flow rate of the heating circuit pump 104 according to requirements.

The thermal management system 12 operates in several operating modes according to predetermined conditions. The predetermined conditions are determined based on, for example, the outside air temperature, the temperature of the airflow blown out from the air conditioning device 26 based on the passenger's request (required blowing temperature), and the cooling request for the battery 18.

Figure 4 is a diagram showing an example of conditions that define the operation mode of the heat management system 12, particularly the operation mode of the air conditioning device 26. In the heating area H where the outdoor air temperature is less than a predetermined temperature T1 (for example, 0°C), the heat management system 12 operates in heating mode, that is, performs heating operation. In the cooling area C where the outdoor air temperature is higher than the predetermined temperature T1, the required blowing temperature is low, and the difference between the required blowing temperature and the outdoor air temperature is large, the heat management system 12 operates in cooling mode, that is, performs cooling operation. In the intermediate dehumidification heating areas Dp and Ds between the heating area H and the cooling area C, the heat management system 12 operates in a dehumidification heating mode in which the air taken in by the air conditioning unit 28 is first cooled and dehumidified, and then heated to the required blowing temperature, that is, performs dehumidification heating operation. The dehumidification heating area is further divided into a parallel dehumidification heating area Dp and a serial dehumidification heating area Ds. The heat management system 12 performs parallel dehumidification heating operation in the parallel dehumidification heating area Dp, and serial dehumidification heating operation in the serial dehumidification heating area Ds. Parallel dehumidification and heating operation is an operation mode in which heating is stronger than in series dehumidification and heating operation. In addition, if the front air conditioning unit 28F and the rear air conditioning unit 28R can set the required blowing temperature independently, the required blowing temperature of one of the air conditioning units 28, for example the front air conditioning unit 28F, which is predetermined, may be the element that defines the operation mode. In addition, the required blowing temperature of the air conditioning unit 28 that is set to a lower temperature may be the element that defines the operation mode. The operation of the thermal management system 12 in each operation mode is described below.

Figures 5 to 7 are diagrams showing the operating state of the thermal management system 12 in the heating region H. In the following description, unless a special distinction is required, the front heater core 44F and the rear heater core 44R will be collectively referred to as the heater core 44.

Figure 5 shows the operating state when the temperature of the engine 14 coolant is sufficiently high. When the temperature of the engine coolant is high, a portion of the engine coolant circulated by the engine cooling circuit pump 110 is supplied to the heater core 44. Engine coolant may be supplied to either or both of the front and rear heater cores 44F, 44R by the driver's operation.

Figure 6 is a diagram showing the operating state when the temperature of the engine coolant is low. When the temperature of the engine coolant is low, the electric heater 38 generates high-temperature liquid, which is supplied to the heater core 44 by the heating circuit pump 104. The high-temperature liquid from the electric heater 38 may be supplied to either or both of the front and rear heater cores 44F, 44R by the operation of the occupant. In addition, for vehicles that do not have an engine 14 and run only on the power of the electric motor 16, heating is performed by the electric heater 38 or by the heat pump operation of the refrigeration cycle circuit 30 described below.

Figure 7 is a diagram showing the operating state in which the refrigeration cycle circuit 30 is operated as a heat pump to perform heating. The refrigerant compressed by the compressor 34 to a high temperature is cooled and liquefied in the liquid-cooled condenser 78 by the liquid circulating in the heating circuit 32. At this time, the circulating liquid in the heating circuit 32 is heated by the high-temperature refrigerant to become a high-temperature liquid. The refrigerant in the refrigeration cycle circuit 30 liquefied in the liquid-cooled condenser 78 passes through the heating expansion valve 92 and expands, and is vaporized in the outdoor condenser 36 to absorb heat from the outside air. In other words, at this time, the outdoor condenser 36 functions as an evaporator. The vaporized refrigerant returns to the compressor 34 through the first bypass flow path 94. In the heating circuit 32, the high-temperature liquid heated in the liquid-cooled condenser 78 is supplied to the heater core 44 by the heating circuit pump 104. The high-temperature liquid from the electric heater 38 may be supplied to either or both of the front and rear heater cores 44F, 44R by the operation of the occupant. During this heat pump operation, the passenger compartment 20 is heated by heat pumped from the outside air.

Figure 8 is a diagram showing the operating state of the thermal management system 12 in the cooling area C. In the following description, unless a special distinction is required, the front evaporator 42F and the rear evaporator 42R are collectively referred to as the evaporator 42. The refrigerant compressed by the compressor 34 releases heat to the outside air in the outdoor condenser 36, and is cooled and liquefied. The liquefied refrigerant expands by passing through the electric expansion valve 84 and the expansion valve 88, and vaporizes and absorbs heat in the front and rear evaporators 42F and 42R, respectively. This cools the passenger compartment 20. Also, when there is no passenger in the rear seat, or when there is no need to cool the rear side of the passenger compartment 20, the solenoid valve 90 may be closed to prevent the refrigerant from being supplied to the rear evaporator 42R.

9 is a diagram showing the operating state of the thermal management system 12 in the parallel dehumidification heating area Dp. The refrigerant compressed by the compressor 34 dissipates heat to the circulating liquid of the heating circuit 32 in the liquid-cooled condenser 78. As a result, high-temperature liquid in the heating circuit 32 is generated and supplied to the heater core 44. As in the heating operation described above, high-temperature liquid may be supplied to either or both of the front heater core 44F and the rear heater core 44R. In the parallel dehumidification heating operation, the amount of heat transferred by the refrigeration cycle circuit 30 is smaller than in the heating operation and cooling operation by the heat pump, so the capacity required of the refrigeration cycle circuit 30 is smaller. For this reason, the output of the compressor 34 is low, and the refrigerant that dissipates heat in the liquid-cooled condenser 78 is not completely liquefied and is in a two-phase gas-liquid state. A portion of the refrigerant flows toward the outdoor condenser 36, passes through the throttled heating expansion valve 92, and at least a portion of the refrigerant vaporizes in the outdoor condenser 36 and absorbs heat. At this time, the outdoor condenser 36 functions as an evaporator. The refrigerant that has passed through the exterior condenser 36 returns to the compressor 34 through the first bypass flow path 94. The remainder of the refrigerant that has passed through the liquid-cooled condenser 78 passes through the second bypass flow path 96 toward the evaporator 42. In the evaporator 42, at least a portion of the liquid-phase refrigerant vaporizes and absorbs heat. After passing through the evaporator 42, the refrigerant returns to the compressor 34. In addition, when there is no need to cool the rear side of the passenger compartment 20, such as when there is no passenger in the rear seat, the solenoid valve 90 may be closed to prevent the refrigerant from being supplied to the rear evaporator 42R.

In the air conditioning unit 28, the water vapor is cooled and condensed by cooling the air in the evaporator 42, and the air is dehumidified. The cooled air is then heated in the heater core 44, and the air conditioning unit 28 sends warm, dry air to the passenger compartment 20.

Figure 10 is a diagram showing the operating state of the thermal management system 12 in the serial dehumidification heating area Ds. The refrigerant compressed by the compressor 34 dissipates heat to the circulating liquid of the heating circuit 32 in the liquid-cooled condenser 78. This generates high-temperature liquid in the heating circuit 32 and supplies it to the heater core 44. As in the heating operation described above, high-temperature liquid may be supplied to either or both of the front heater core 44F and the rear heater core 44R. The entire amount of refrigerant that passes through the liquid-cooled condenser 78 is sent to the outdoor condenser 36. In the outdoor condenser 36, when the amount of heat dissipated by the refrigerant in the liquid-cooled condenser 78 is large, that is, when heating is performed at a high level, the refrigerant absorbs heat in the same manner as in the parallel dehumidification heating operation. By narrowing the opening of the heating expansion valve 92, part of the refrigerant vaporizes and absorbs heat in the outdoor condenser 36. On the other hand, when heating can be performed at a low level, the refrigerant dissipates heat in the outdoor condenser 36. At this time, the heating expansion valve 92 is fully open. In the serial dehumidification heating operation, the amount of heat transferred by the refrigeration cycle circuit 30 is smaller than in the heating operation and cooling operation by the heat pump, so the capacity required of the refrigeration cycle circuit 30 is smaller. Therefore, the output of the compressor 34 is low, and the refrigerant that has dissipated heat in the liquid cooling condenser 78 and the exterior condenser 36 is not completely liquefied and is in a two-phase gas-liquid state. The two-phase gas-liquid refrigerant heads to the evaporator 42. In the evaporator 42, the liquid refrigerant vaporizes and absorbs heat. After passing through the evaporator 42, the refrigerant returns to the compressor 34. In addition, when there is no passenger in the rear seat, or when there is no need to cool the rear side of the passenger compartment 20, the solenoid valve 90 may be closed to prevent the refrigerant from being supplied to the rear evaporator 42R.

During heating operation, the refrigeration cycle circuit 30 transfers heat from the outside into the passenger compartment 20 to heat the passenger compartment 20, and during cooling operation, it transfers heat from within the passenger compartment 20 to the outside to cool the passenger compartment. During dehumidification and heating operation, the refrigeration cycle circuit 30 absorbs heat from the evaporator 42 and dissipates heat from the heater core 44 via the heating circuit 32 to transfer heat within the passenger compartment 20. The difference between the amount of heat absorbed by the evaporator 42 and the amount of heat dissipated by the liquid-cooled condenser 78 is absorbed or dissipated by the exterior condenser 36.

In the dehumidifying and heating operation, the heat transfer is smaller than in the heating and cooling operations, and the output of the compressor 34 is also suppressed. Therefore, the refrigerant after heat dissipation does not completely liquefy, but remains in a gas-liquid two-phase state. Therefore, the amount of heat absorbed by the evaporator 42 is small, and the temperature drop of the air passing through the evaporator 42 is small. On the other hand, in the bi-level operation, a sufficient difference in temperature is provided between the cold air blown toward the upper body of the occupant and the warm air blown toward the feet, and a sharp air conditioning is desired. To achieve this, the refrigeration cycle circuit 30 needs to supply sufficient liquid phase refrigerant to the evaporator 42 even in the dehumidifying and heating regions Dp and Ds. In addition, in order to warm the air that has been strongly cooled by the evaporator 42 to which sufficient liquid phase refrigerant is supplied, it is necessary to supply the engine cooling water or high-temperature liquid heated by the electric heater 38 to the heater core 44. Furthermore, when refrigerant is supplied to both the front evaporator 42F and the rear evaporator 42R, if the refrigerant is in a gas-liquid two-phase state, it may not be possible to distribute the liquid refrigerant evenly to both evaporators, or to distribute the amount required for each evaporator. If the supply of refrigerant is insufficient, it may not be possible to sufficiently lower the temperature of the air blown onto the upper bodies of the occupants.

When both the front and rear air conditioning units 28F, 28R are operating (dual mode) in the dehumidifying and heating areas Dp, Ds, the thermal management system 12, upon a request for bi-level operation, operates the refrigeration cycle circuit 30 in cooling mode to supply liquid refrigerant to the evaporator 42, and supplies high-temperature liquid heated by the electric heater 38 to the heater core 44. During cooling mode operation of the refrigeration cycle circuit 30, the compressor 34 operates at high output, sufficiently compressing the refrigerant, which is then completely liquefied by dissipating heat in the outdoor condenser 36. This allows the required amount of liquid refrigerant to be supplied to the front and rear evaporators 42F, 42R.

Figure 11 is a diagram showing the operating state of the thermal management system 12 in which the air conditioner 26 operates in dual mode and bi-level mode in the dehumidification heating area Dp, Ds. In the refrigeration cycle circuit 30, the refrigerant compressed by the compressor 34 is sent to the outdoor condenser 36, where it dissipates heat and is completely liquefied. The liquid phase refrigerant is supplied to the front and rear evaporators 42F, 42R. The refrigerant sent to the front and rear evaporators 42F, 42R vaporizes here and absorbs heat from the air in the passenger compartment 20. In the heating circuit 32, the electric heater 38 operates to generate high-temperature liquid, which is supplied to the heater core 44. If the engine 14 coolant is sufficiently hot, the engine coolant may be supplied to the front and rear heater cores 44F, 44R.

Figure 12 shows the control flow of the thermal management system 12 when both the front and rear air conditioning units 28F, 28R are performing dehumidification heating operation and there is a request for bi-level operation. The control unit 60 controls the thermal management system 12 according to this control flow.

When the rear air conditioning switch 67 is on, that is, when both the front and rear air conditioning units 28F, 28R are operating in dual mode (S100), and the operating condition is the dehumidification heating area Dp, Ds (S102), the control unit 60 further judges whether or not there is a request for bi-level operation (S104). The request for bi-level operation is judged, for example, based on the operation of the bi-level switch 65 by the occupant. The bi-level mode can be set independently for the front air conditioning unit 28F and the rear air conditioning unit 28R, and when the bi-level mode is selected in at least one of the air conditioning units 28, the control unit 60 judges that there is a request for bi-level operation. If the dual mode is not selected in step S100, the dehumidification heating area Dp, Ds is not selected in step S102, and there is no request for bi-level operation in step S104, the process returns to the start of this control flow. If the control unit 60 determines in step S104 that there is a request for bi-level operation, it controls the refrigeration cycle circuit 30 to perform cooling operation and the heating circuit 32 to perform heating operation (S106).

When refrigerant is supplied to the front and rear evaporators 42F, 42R, the refrigeration cycle circuit 30 operates in cooling mode, allowing only liquid-phase refrigerant to be sent toward the two targets. This allows the front and rear evaporators 42F, 42R to more strongly cool the air passing through them than when refrigerant in a gas-liquid two-phase state is sent. Meanwhile, by supplying high-temperature liquid to the front and rear heater cores 44F, 44R by the heating circuit 32, the once-cooled air passing through them can be reheated to generate warm air. This allows the air conditioning unit 26 to blow cool air toward the upper bodies of occupants and warm air toward their feet.

10 vehicle, 12 thermal management system, 14 engine, 16 electric motor, 18 battery, 20 passenger compartment, 22 engine radiator, 26 air conditioning device, 28 air conditioning unit, 28F front air conditioning unit, 28R rear air conditioning unit, 30 refrigeration cycle circuit, 32 heating circuit, 34 compressor, 36 exterior condenser, 38 electric heater, 40 battery cooling circuit, 41 battery cooling heat exchanger, 42 evaporator, 42F front evaporator, 42R rear evaporator, 44 heater core, 44F front heater core, 44R rear heater core, 60 control unit, 65 bi-level switch, 78 liquid-cooled condenser, 84, 86 electric expansion valve, 88 expansion valve, 90 solenoid valve, 92 heating expansion valve, 94 first bypass flow path, 96 second bypass flow path, 98 Battery cooling circuit pump, 104 heating circuit pump, 106 engine cooling circuit, 108 three-way valve.

Claims (2)

A front air conditioning unit that conditions air in a front space of a vehicle passenger compartment;
A rear air conditioning unit that conditions air in a rear space of the vehicle passenger compartment;
a refrigeration cycle circuit for supplying a refrigerant to the front air conditioning unit and the rear air conditioning unit;
a heating circuit that generates a high-temperature liquid using a heat source or a refrigerant in the refrigeration cycle circuit and supplies the high-temperature liquid to the front air conditioning unit and the rear air conditioning unit;
A vehicle air conditioning device comprising:
In a dehumidifying and heating operation region determined based on a required blowing temperature, which is a control target for the temperature of air delivered from the front air conditioning unit and the rear air conditioning unit, and an outside air temperature, when the front air conditioning unit and the rear air conditioning unit are in an operating state and at least one of the front air conditioning unit and the rear air conditioning unit performs a bi-level operation in which cool air is delivered to the upper bodies of occupants and warm air is delivered to the feet of the occupants,
the refrigeration cycle circuit performs a cooling operation to supply a refrigerant to the front air conditioning unit and the rear air conditioning unit;
The heating circuit generates a high-temperature liquid using the heat source and supplies the high-temperature liquid to the front air conditioning unit and the rear air conditioning unit.
Vehicle air conditioning system. 2. The vehicle air conditioning system according to claim 1, wherein the heat source of the heating circuit is one or both of an engine that drives the vehicle and an electric heater.

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