Vehicle air conditioning system

Abstract

To clarify a temperature difference between cold air and warm air when operating in a bi-level mode during dehumidification heating in an air conditioner for vehicle.SOLUTION: In a case where front and rear air conditioning units 28F, 28R are operating together under the condition that an air conditioner 26 performs dehumidification heating, when a bi-level mode to send cold air to the upper body of an occupant and warm air to the footing is selected, a refrigeration cycle circuit 30 performs a 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 and 42R to strongly cool the air. A portion of the cooled air is blown into the upper body of the occupant. The cooled air residue is also warmed by the high temperature liquid supplied to front and rear heater cores 44F, 44R and blown into the footing.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a vehicle air conditioner that conditions the air in the passenger compartment of a vehicle.

Background Art

[0002] Patent Document 1 below discloses a vehicle air conditioner that dehumidifies and heats the passenger compartment of a vehicle using a refrigeration cycle. An evaporator (2) and a radiator (4) are arranged in an air conditioning casing (1) that serves as a passage for air sent to the passenger compartment. When dehumidifying and heating, the refrigerant compressed by the compressor (7) and heated to a high temperature is sent to the radiator (4). The refrigerant is sent from the radiator (4) to the outdoor heat exchanger (8) to be cooled, and then sent to the evaporator (2). In the air conditioning casing (1), the air is cooled by the evaporator (2), and 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.

[0003] In addition, a vehicle air conditioner is known in which an air conditioning unit for conditioning the air in the front space of the passenger compartment and an air conditioning unit for conditioning the air in the rear space are provided separately. Furthermore, a vehicle air conditioner having a so-called bi-level mode in which cold air is blown toward the upper body of the passenger and warm air is blown toward the feet is known.

[0004] Note that the reference numerals in the above ( ) are the reference numerals used in Patent Document 1 below and are not related to the reference numerals used in the description of the embodiments of the present application.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When a vehicle's air conditioning system operates in bi-level mode, it is necessary to clearly define the temperature difference between the cool air directed towards the occupants' upper bodies and the warm air directed towards their feet. In dehumidifying heating operation, it can be difficult to create a sufficient temperature difference between the cool and warm air. Furthermore, in dehumidifying heating operation, if the refrigerant supplied to the air conditioning unit is a two-phase gas-liquid system, it may not be possible to properly distribute the refrigerant supplied to the front and rear air conditioning units. In air conditioning units with insufficient refrigerant, the temperature of the cool air may not be sufficiently lowered.

[0007] The present invention ensures that when the front and rear air conditioning units operate together under conditions of dehumidification, and at least one of the air conditioning units performs bi-level operation, the air conditioning units deliver cool and warm air at appropriate temperatures. [Means for solving the problem]

[0008] The vehicle air conditioning system according to the present invention comprises a front air conditioning unit that provides air conditioning to the front space of the vehicle occupant's compartment, a rear air conditioning unit that provides air conditioning to the rear space of the vehicle occupant's compartment, and a refrigerant supplied to the front air conditioning unit and the rear air conditioning unit. Distribute The system comprises a refrigeration cycle circuit that supplies a refrigerant, and a heating circuit that generates a high-temperature liquid using a heat source or the refrigerant in the refrigeration cycle circuit, and supplies the high-temperature liquid to the front air conditioning unit and the rear air conditioning unit. The refrigeration cycle circuit can operate in both cooling mode, where the refrigerant supplied to the front and rear air conditioning units is completely liquefied, and dehumidifying heating mode, where the refrigerant is in a two-phase gas-liquid state. The dehumidifying and heating operation range is defined by the required discharge temperature, which is the target temperature for the air delivered from the front and rear air conditioning units, and the outside temperature. In the dehumidifying heating operation range, the refrigeration cycle circuit performs dehumidifying heating operation. In the dehumidifying and heating operation range, when the front and rear air conditioning units are operating and at least one of them is performing bi-level operation, supplying cool air to the occupant's upper body and warm air to their feet, the refrigeration cycle circuit operates in cooling mode, supplying 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.

[0009] When the refrigeration cycle circuit is operated in cooling mode, only the liquid phase of the refrigerant is used. This ensures that the liquid phase refrigerant is properly distributed to the front and rear air conditioning units, generating sufficiently cooled air in both units. Additionally, the heating circuit generates warm air in both the front and rear air conditioning units.

[0010] In the above-described vehicle air conditioning system, the heat source of the heating circuit may be either the engine that drives the vehicle or an electric heater, or both. [Effects of the Invention]

[0011] In the front and rear air conditioning units, sufficiently cooled cold air and sufficiently warm air are generated, resulting in a clear temperature difference between the cold air blown towards the occupants' upper bodies and the warm air blown towards their feet. [Brief explanation of the drawing]

[0012] [Figure 1] This diagram shows a schematic configuration of a vehicle equipped with a thermal management system including the vehicle air conditioning system of this embodiment. [Figure 2] This figure shows the front air conditioning unit and its control unit. [Figure 3] This figure schematically shows the configuration of the thermal management system according to this embodiment. [Figure 4] This diagram shows the conditions that define the operating mode of an air conditioning system. [Figure 5] This diagram shows the operating status of the thermal management system, and in particular, the state during heating operation using engine coolant. [Figure 6] This diagram shows the operating status of the thermal management system, and in particular, the state during heating operation using electric heaters. [Figure 7] This diagram shows the operating status of the thermal management system, and in particular, the state during heating operation using the heat pump in the refrigeration cycle circuit. [Figure 8] This diagram shows the operating status of the thermal management system, and specifically the state during cooling operation. [Figure 9] It is a diagram showing the operating state of the heat management system, and particularly a diagram showing the state during parallel dehumidifying and heating operation. [Figure 10] It is a diagram showing the operating state of the heat management system, and particularly a diagram showing the state during series dehumidifying and heating operation. [Figure 11] It is a diagram showing the operating state of the heat management system, and particularly a diagram showing the state in the dehumidifying and heating region where the front and rear air conditioning units are operating and at least one of them is operating in a bi-level mode. [Figure 12] It is a diagram showing a part of the control flow of the heat management system.

Embodiments for Carrying out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic configuration of a heat management system 12 of a vehicle 10. The vehicle 10 is equipped with an engine 14 as a prime mover for driving the vehicle 10, and two electric motors, namely 16F and 16R, for driving the front and rear wheels respectively. The vehicle 10 is equipped with a battery 18 that supplies power to the electric motors 16F and 16R and is charged with the power generated by the electric motors 16F and 16R during braking. The vehicle may be a vehicle equipped with one electric motor for driving only the front or rear wheels. Further, the vehicle may be a vehicle that does not have an engine and drives one or both of the front and rear wheels with an electric motor. Hereinafter, for simplicity, the electric motors 16F and 16R will be simply referred to as the motor 16.

[0014] The thermal management system 12 cools the engine 14, the motor 16, and the battery 18, and further conditions the air in the passenger compartment 20. The cooling system of the engine 14 includes an engine radiator 22 that dissipates the heat generated by the engine via 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 of the motor 16 includes a motor radiator 24 that dissipates the heat generated by the motor 16 via 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.

[0015] The thermal management system 12 includes an air conditioning device 26 that conditions the air in the passenger compartment 20. The air conditioning device 26 has an air conditioning unit 28 that supplies air with adjusted temperature, humidity, etc. to the passenger compartment 20. The air conditioning unit 28 includes a front air conditioning unit 28F that conditions the air in the space on the front seat side of the passenger compartment 20 and a rear air conditioning unit 28R that conditions the air in the space on the rear seat side. The air conditioning device 26 includes, in the air conditioning unit 28, a refrigeration cycle circuit 30 that sends refrigerant 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 rotational 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, including other cooling systems of the thermal management system 12, will be described in more detail later.

[0016] The thermal management system 12 further includes a battery cooling circuit 40 that cools the battery 18. The battery cooling circuit 40 supplies battery coolant cooled by the refrigerant of the refrigeration cycle circuit 30 to the battery 18 via a battery cooling heat exchanger 41 to cool the battery 18.

[0017] Figure 2 is a schematic diagram showing the 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 for introducing air into the air conditioning case 46. The air inlet 48 includes an internal air inlet 48C for introducing air from inside the occupant compartment 20 and an external air inlet 48E for introducing air from outside the vehicle. The air conditioning case 46 also has an air outlet 50 for sending conditioned air toward a predetermined location. The air outlet 50 includes a head outlet 50H that delivers airflow toward the upper body of the occupant seated in the front seat, i.e., the head and its surroundings; a foot outlet 50F that delivers airflow toward the feet of the front occupant; and a defroster outlet 50D that delivers airflow toward the interior surface of the windshield. The airflow delivered from the head outlet 50H passes through a duct in the instrument panel (not shown) and is blown out from multiple outlets formed in the instrument panel toward the head and surroundings of the front occupant in the passenger compartment 20. The airflow delivered from the foot outlet 50F is blown out either directly from the foot outlet 50F or through a duct in the instrument panel toward the feet of the front occupant. Furthermore, the airflow delivered from the defroster outlet 50D passes through a duct in the instrument panel and is blown out from an outlet located opposite the lower edge of the windshield. The front air conditioning unit 28F has a blower 52 located upstream of the air conditioning case 46. The blower 52 generates an airflow from the air inlet 48 to the air outlet 50.

[0018] An internal / external air switching door 54 is positioned at the junction of the airflow path from the internal air inlet 48C and the airflow path from the external air inlet 48E. The internal / external air switching door 54 is rotatable between a position that closes the internal air inlet 48C and a position that closes the external air inlet 48E, and the mixing ratio of internal and external air is adjusted according to the rotation angle. An air mix door 56 is positioned 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 from the air that has passed through the front evaporator 42F. Corresponding to each air outlet 50, an outlet door 58 is provided to open and close the air outlet 50. Specifically, a head outlet door 58H is provided for the head outlet 50H, a foot outlet door 58F is provided for the foot outlet 50F, and a defroster outlet door 58D is provided for the defroster outlet 50D. The amount of air blown from each outlet 50 is adjusted by the degree to which each outlet door 58 is opened.

[0019] The airflow rate of the blower 52, the rotation angles of the internal / external air switching door 54 and the air mix door 56, and the opening degree of each outlet door 58 are controlled by the control unit 60. Based on the conditions set by the occupant and the environmental conditions, the control unit 60 controls the rotation angles of the internal / external air switching door 54 and the air mix door 56, the opening degree of each outlet door 58, and the airflow rate of the blower 52. The occupant sets the desired temperature using the temperature setting switch 62 and then sets the desired air outlet 50 using the outlet selection switch 64. The selection of the air outlet 50 can be done in several ways, including selecting one of the air outlets 50H, 50F, or 50D individually, or selecting an air outlet mode that blows air from both the head outlet 50H and the foot outlet 50F. Furthermore, the occupants can set the automatic air conditioning mode using the automatic air conditioning switch 66. In this case, the control unit 60 selects the air outlet 50 for blowing air according to a predetermined program, based on the desired temperature and environmental conditions. The control unit 60 receives input such as the ambient temperature of the occupant compartment 20 detected by the ambient temperature sensor 68, the ambient temperature detected by the ambient temperature sensor 70, the liquid temperature of the heating circuit 32 detected by the liquid temperature sensor 72, and the amount of solar radiation entering the occupant compartment 20 detected by the solar radiation sensor 74. In addition, the control unit 60 receives input of the temperature of the air immediately after it passes through the front evaporator 42F (evaporator outlet temperature), which is detected by the evaporator outlet temperature sensor 76 located immediately after the front evaporator 42F.

[0020] The air conditioning unit 26 is capable of operating in a so-called bi-level mode (hereinafter referred to as bi-level operation), which sends cool air towards the upper body of the front seat occupant and warm air towards their feet. Bi-level operation is performed, for example, by an occupant operating a bi-level switch 65 provided on the outlet selector switch 64. In 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 airflow. Regarding the outlet doors 58, the head outlet door 58H and the foot outlet door 58F are opened. Air taken into the air conditioning case 46 by the blower 52 is sent out from the head outlet 50H and the foot outlet 50F, blown towards the upper body and feet of the occupant, respectively. The air mix door 56 is positioned to guide a portion 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 bi-level operation, the refrigerant is supplied to the front evaporator 42F by the refrigeration cycle circuit 30, where it vaporizes and absorbs heat from the air passing through the front evaporator 42F. As a result, the air passing through the front evaporator 42F is cooled, and the water vapor in the air condenses, dehumidifying the air. In addition, the heating circuit 32 sends high-temperature liquid to the front heater core 44F, warming the air passing through the front heater core 44F. In other words, the air that has been cooled in the front evaporator 42F is warmed in the front heater core 44F, becoming dry, warm air. The air that has passed through the front heater core 44F is guided to the foot outlet 50F and discharged from there. On the other hand, the air that bypasses the front heater core 44F is guided to the head outlet 50H while still cold and discharged from there. An air guide plate (not shown) may be installed inside the air conditioning case 46 to direct the warm air that has passed through the front heater core 44F to the foot outlet 50F, and the rerouted cool air to the head outlet 50H.

[0021] The rear air conditioning unit 28R has a configuration almost identical to that of the front air conditioning unit 28F, and is not shown in the diagram. The rear air conditioning unit 28R has an air conditioning case that houses the rear evaporator 42R and the rear heater core 44R (see Figure 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 can deliver conditioned air to the upper body and feet of the rear seat occupants, similar to the front air conditioning unit 28F.

[0022] The rear air conditioning unit 28R can be switched on and off by the occupant. By operating 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 have their temperature settings and airflow modes selected independently. Furthermore, the rear air conditioning unit 28R can operate in a bi-level configuration, either in conjunction with or independently of the front air conditioning unit 28F.

[0023] The control unit 60 is a processing device that controls the air conditioning system 26 according to a predetermined program and operates to achieve the temperature and airflow mode desired by the occupants according to the above-mentioned temperature, solar radiation, etc.

[0024] Figure 3 is a schematic diagram showing the configuration of the thermal management system 12. Components already described are denoted by the same reference numerals. The refrigeration cycle circuit 30 includes the compressor 34, outdoor condenser 36, front and rear evaporators 42F and 42R, as well as the outdoor condenser 36, 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, electrically operated expansion valves 84 and 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 a solenoid valve 90 are provided upstream of the rear evaporator 42R. The electrically operated expansion valves 84 and 86 cannot be completely closed, and even when the opening degree is at its 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 heating expansion valve 92 has an adjustable opening and 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, which has a reduced opening, and vaporizes in the outdoor condenser 36, absorbing 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 open, allowing the refrigerant to simply pass through. The capacity of the refrigeration cycle circuit 30 is adjusted by adjusting the output of the compressor 34 and adjusting the opening of each expansion valve 84, 86, 88, 92.

[0025] The refrigeration cycle circuit 30 has a first bypass channel 94 arranged in parallel with the front and rear evaporators 42F, 42R and the heat exchanger 41 for battery cooling. The refrigerant can bypass the front and rear evaporators 42F, 42R and the heat exchanger 41 for battery cooling by passing through the first bypass channel 94. The refrigeration cycle circuit 30 also has a second bypass channel 96 arranged in parallel with the outdoor condenser 36, and the refrigerant can bypass the outdoor condenser 36 by passing through the second bypass channel 96.

[0026] 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 the coolant cooled by the battery cooling heat exchanger 41 to the battery 18. The battery 18 is equipped with a battery temperature sensor 100 that detects the temperature of the battery 18. Based on the temperature of the battery 18, the level of cooling requirement for the battery 18 is determined, and the battery cooling circuit 40 is controlled according to the level.

[0027] The heating circuit 32 includes an electric heater 38, front and rear heater cores 44F and 44R, a liquid-cooled condenser 78, and a heating circuit pump 104 that supplies high-temperature liquid. The heating circuit pump 104 circulates the circulating liquid through the electric heater 38, the front and rear heater cores 44F and 44R, and the liquid-cooled condenser 78. The liquid-cooled condenser 78 heats the circulating liquid in 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 and 44R. The heating circuit 32 also shares heating / cooling liquid with the engine cooling circuit 106 and can utilize the engine 14 as a heat source. Whether the high-temperature liquid supplied to the front and rear heater cores 44F and 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.

[0028] 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 passage 112 arranged in parallel with the engine radiator 22, allowing the engine coolant to circulate by bypassing the engine radiator 22. When the engine 14 is cold, such as during warm-up, the engine cooling circuit 106 can quickly raise the temperature of the engine coolant by circulating it through the radiator bypass passage 112 instead of sending it to the engine radiator 22. As mentioned above, the engine coolant can be shared with the circulating fluid of the heating circuit 32.

[0029] 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 changes in the flow paths of the refrigerant or liquid are achieved by the operation of multiple valves (not shown) appropriately provided in each circuit, in addition to the three-way valve 108 and solenoid valve 90 already described. The opening and closing and degree of opening 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 as needed.

[0030] The thermal management system 12 operates in several operating modes according to predetermined conditions. These predetermined conditions are determined, for example, based on the outside temperature, the temperature of the airflow blown out from the air conditioning unit 26 based on the occupant's requirements (required discharge temperature), and the cooling requirements of the battery 18.

[0031] Figure 4 shows an example of the conditions that define the operating modes of the thermal management system 12, particularly the operating modes of the air conditioning system 26. In the heating region H, where the outside temperature is below a predetermined temperature T1 (e.g., 0°C), the thermal management system 12 operates in heating mode, i.e., performs heating operation. In the cooling region C, where the outside temperature is higher than the predetermined temperature T1, the required discharge temperature is low, and the difference between the required discharge temperature and the outside temperature is large, the thermal management system 12 operates in cooling mode, i.e., performs cooling operation. In the intermediate dehumidifying heating regions Dp and Ds between the heating region H and the cooling region C, the thermal management system 12 operates in dehumidifying heating mode, where the air taken in by the air conditioning unit 28 is first cooled and dehumidified, and then heated to the required discharge temperature, i.e., performs dehumidifying heating operation. The dehumidifying heating region is further divided into a parallel dehumidifying heating region Dp and a series dehumidifying heating region Ds. The thermal management system 12 performs parallel dehumidifying heating operation in the parallel dehumidifying heating region Dp and series dehumidifying heating operation in the series dehumidifying heating region Ds. Parallel dehumidification and heating operation is an operating mode in a range where heating is stronger compared to series dehumidification and heating operation. Furthermore, if the front air conditioning unit 28F and the rear air conditioning unit 28R can independently set their required discharge temperatures, the required discharge temperature of one of the predetermined air conditioning units 28, for example, the front air conditioning unit 28F, may be used as an element to define the operating mode. Alternatively, the required discharge temperature of the air conditioning unit 28 set to a lower temperature may be used as an element to define the operating mode. The operation of the thermal management system 12 in each operating mode will be described below.

[0032] Figures 5-7 show the operating state of the thermal management system 12 in the heating region H. In the following description, unless otherwise specified, the front heater core 44F and the rear heater core 44R will be collectively referred to as heater core 44.

[0033] Figure 5 shows the operating state when the engine coolant temperature of the engine 14 is sufficiently high. When the engine coolant temperature is high, a portion of the engine coolant circulating by the engine cooling circuit pump 110 is supplied to the heater core 44. The engine coolant may be supplied to either the front or rear heater cores 44F, 44R, or both, by operation by the occupant.

[0034] Figure 6 shows the operating state when the engine coolant temperature is low. When the engine coolant temperature is low, the electric heater 38 generates high-temperature fluid, which is supplied to the heater core 44 by the heating circuit pump 104. The occupant can operate the system to supply high-temperature fluid from the electric heater 38 to either or both of the front and rear heater cores 44F and 44R. In addition, for vehicles that do not have an engine 14 and run solely on the power of the electric motor 16, heating is provided by the electric heater 38 or by the heat pump operation of the refrigeration cycle circuit 30 described below.

[0035] Figure 7 shows the operating state of the refrigeration cycle circuit 30 when it is operated by a heat pump to provide heating. The refrigerant, which has been compressed to a high temperature by the compressor 34, 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 and becomes a high-temperature liquid. The refrigerant of the refrigeration cycle circuit 30 that has been liquefied in the liquid-cooled condenser 78 expands as it passes through the heating expansion valve 92 and vaporizes in the outdoor condenser 36, absorbing 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 passage 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 operation by the occupant. In this heat pump operation, the crew compartment 20 is heated by heat drawn from the outside air.

[0036] Figure 8 shows the operating state of the thermal management system 12 in the cooling region C. In the following description, unless otherwise specified, the front evaporator 42F and the rear evaporator 42R will be collectively referred to as evaporator 42. The refrigerant compressed by the compressor 34 dissipates heat to the outside air in the outdoor condenser 36, cooling itself and liquefying. The liquefied refrigerant expands as it passes through the electric expansion valve 84 and expansion valve 88, and vaporizes and absorbs heat in the front and rear evaporators 42F and 42R, respectively. This cools the passenger compartment 20. Furthermore, when there is no need to cool the rear of the passenger compartment 20, such as when there are no passengers in the rear seats, the solenoid valve 90 may be closed to prevent the refrigerant from being supplied to the rear evaporator 42R.

[0037] Figure 9 shows the operating state of the thermal management system 12 in the parallel dehumidification heating region Dp. The refrigerant compressed by the compressor 34 releases heat to the circulating liquid in the heating circuit 32 via the liquid-cooled condenser 78. This generates high-temperature liquid in the heating circuit 32, which is supplied to the heater core 44. Similar to the heating operation described above, the high-temperature liquid may be supplied to either or both of the front heater core 44F and the rear heater core 44R. In parallel dehumidification heating operation, the amount of heat transferred by the refrigeration cycle circuit 30 is less than in heating and cooling operations using a 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 releases heat in the liquid-cooled condenser 78 does not completely liquefy, remaining in a two-phase gas-liquid state. A portion of the refrigerant heads toward the outdoor condenser 36, passes through the restricted heating expansion valve 92, and at least a portion of it vaporizes in the outdoor condenser 36, absorbing heat. At this time, the outdoor condenser 36 functions as an evaporator. The refrigerant that has passed through the outdoor condenser 36 returns to the compressor 34 via the first bypass passage 94. The remaining refrigerant that has passed through the liquid-cooled condenser 78 goes to the evaporator 42 via the second bypass passage 96. At least a portion of the liquid-phase refrigerant vaporizes in the evaporator 42, absorbing 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 of the passenger compartment 20, such as when there are no passengers in the rear seats, the solenoid valve 90 may be closed to prevent the refrigerant from being supplied to the rear evaporator 42R.

[0038] In the air conditioning unit 28, the evaporator 42 cools the air, causing water vapor to cool and condense, thus dehumidifying it. By heating the cooled air in the heater core 44, the air conditioning unit 28 sends warm, dry air to the crew compartment 20.

[0039] Figure 10 shows the operating state of the thermal management system 12 in the series dehumidification heating region Ds. The refrigerant compressed by the compressor 34 is released into the circulating liquid of the heating circuit 32 by the liquid-cooled condenser 78. This generates high-temperature liquid in the heating circuit 32, which is supplied to the heater core 44. As with the heating operation described above, the 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 has passed through the liquid-cooled condenser 78 is sent to the outdoor condenser 36. In the outdoor condenser 36, when a large amount of heat is released by the refrigerant in the liquid-cooled condenser 78, that is, when heating is increased, the refrigerant absorbs heat, similar to the parallel dehumidification heating operation. By narrowing the opening of the heating expansion valve 92, a portion of the refrigerant vaporizes and absorbs heat in the outdoor condenser 36. On the other hand, when heating is not required, the refrigerant releases heat in the outdoor condenser 36. In this case, the heating expansion valve 92 is fully open. In series dehumidifying heating operation, the amount of heat transferred by the refrigeration cycle circuit 30 is less than in heating and cooling operations using a heat pump, so the required capacity of the refrigeration cycle circuit 30 is reduced. As a result, the output of the compressor 34 is low, and the refrigerant that has dissipated heat in the liquid-cooled condenser 78 and the outdoor condenser 36 does not completely liquefy, remaining in a two-phase gas-liquid state. The gas-liquid two-phase refrigerant moves towards the evaporator 42. In the evaporator 42, the liquid phase refrigerant vaporizes and absorbs heat. After passing through the evaporator 42, the refrigerant returns to the compressor 34. Also, when there are no passengers in the rear seats, or when there is no need to cool the rear of the passenger compartment 20, the solenoid valve 90 can be closed to prevent the refrigerant from being supplied to the rear evaporator 42R.

[0040] The refrigeration cycle circuit 30 heats the occupant compartment 20 by transferring heat from the outside during heating operation, and cools the occupant compartment 20 by transferring heat from the occupant compartment 20 to the outside during cooling operation. In dehumidifying heating operation, the refrigeration cycle circuit 30 absorbs heat from the evaporator 42 and releases heat from the heater core 44 via the heating circuit 32, transferring heat within the occupant compartment 20. The difference between the amount of heat absorbed by the evaporator 42 and the amount of heat released by the liquid-cooled condenser 78 is absorbed or released by the outdoor condenser 36.

[0041] In dehumidifying heating operation, less heat is transferred compared to heating and cooling operation, and the output of the compressor 34 is also reduced. As a result, the refrigerant does not completely liquefy after heat dissipation, remaining in a gas-liquid two-phase state. Consequently, the amount of heat absorbed by the evaporator 42 is reduced, and the temperature drop of the air passing through the evaporator 42 is small. On the other hand, in bi-level operation, a sufficient temperature difference is desired between the cool air blown towards the occupants' upper bodies and the warm air blown towards their feet, resulting in a more distinct air conditioning experience. To achieve this, the refrigeration cycle circuit 30 needs to supply sufficient liquid-phase refrigerant to the evaporator 42 even in the dehumidifying heating regions Dp and Ds. Furthermore, in order to warm the air that has been strongly cooled by the evaporator 42, which is supplied with sufficient liquid-phase refrigerant, it is necessary to supply engine coolant or high-temperature liquid heated by the electric heater 38 to the heater core 44. Furthermore, when supplying refrigerant 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 phase refrigerant equally to both, or to distribute the required amount to each. If the refrigerant supply is insufficient, the temperature of the air blown onto the occupants' upper bodies may not be sufficiently lowered.

[0042] When both the front and rear air conditioning units 28F and 28R are operating (dual mode) in the dehumidifying and heating zones Dp and Ds, the thermal management system 12, upon request for bi-level operation, operates the refrigeration cycle circuit 30 in cooling mode, supplying liquid-phase refrigerant to the evaporator 42, and supplying high-temperature liquid heated by the electric heater 38 to the heater core 44. During the cooling operation of the refrigeration cycle circuit 30, the compressor 34 operates at high output, compressing the refrigerant sufficiently and dissipating heat in the outdoor condenser 36, causing it to completely liquefy. As a result, the required amount of liquid-phase refrigerant is supplied to the front and rear evaporators 42F and 42R.

[0043] Figure 11 shows the operating state of the thermal management system 12 when the air conditioning unit 26 is operating in dual mode and bi-level mode in the dehumidifying heating regions Dp and 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 the entire amount liquefies. The liquid phase refrigerant is supplied to the front and rear evaporators 42F and 42R. The refrigerant sent to the front and rear evaporators 42F and 42R vaporizes there 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 coolant of the engine 14 is sufficiently hot, the engine coolant may be supplied to the front and rear heater cores 44F and 44R.

[0044] Figure 12 shows the control flow of the thermal management system 12 when both the front and rear air conditioning units 28F and 28R are performing dehumidifying and heating operations, and a request for bi-level operation is also made. The control unit 60 controls the thermal management system 12 according to this control flow.

[0045] When the rear air conditioning switch 67 is ON, meaning both the front and rear air conditioning units 28F and 28R are operating in dual mode (S100), and the operating conditions are in the dehumidifying heating area Dp, Ds (S102), the control unit 60 further determines whether there is a request for bilevel operation (S104). The request for bilevel operation is determined, for example, based on the operation of the occupant's bilevel switch 65. The bilevel mode can be set independently for the front air conditioning unit 28F and the rear air conditioning unit 28R, and when the bilevel mode is selected for at least one of the air conditioning units 28, the control unit 60 determines that there is a request for bilevel operation. If it is not dual mode in step S100, not in the dehumidifying heating area Dp, Ds in step S102, and there is no request for bilevel 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 bilevel operation, it controls the refrigeration cycle circuit 30 to operate in cooling mode and controls the heating circuit 32 to operate in heating mode (S106).

[0046] When refrigerant is supplied to the front and rear evaporators 42F and 42R, the refrigeration cycle circuit 30 operates in cooling mode, allowing only liquid-phase refrigerant to be delivered to the two targets. This allows the front and rear evaporators 42F and 42R to cool the air passing through them more strongly compared to when a gas-liquid two-phase refrigerant is delivered. On the other hand, by supplying high-temperature liquid to the front and rear heater cores 44F and 44R via the heating circuit 32, the cooled air passing through them can be reheated to generate warm air. As a result, the air conditioning system 26 can blow cool air towards the occupants' upper bodies and warm air towards their feet. [Explanation of symbols]

[0047] 10 vehicles, 12 thermal management systems, 14 engines, 16 electric motors, 18 batteries 20 Crew compartment, 22 Engine radiator, 26 Air conditioning system, 28 Air conditioning unit, 28F Front air conditioning unit, 28R Rear air conditioning unit, 30 Refrigeration cycle circuit, 32 Heating circuit, 34 Compressor, 36 Outdoor condenser, 38 Electric heater, 40 Battery cooling circuit, 41 Heat exchanger for battery cooling, 42 Evaporator, 42F Front evaporator, 42R Rear evaporator, 44 Heater core, 44F Front heater core, 44R Rear heater core, 60 Control unit, 65 Bilevel switch, 78 Liquid-cooled condenser, 84, 86 Electric expansion valve, 88 Expansion valve, 90 Solenoid valve, 92 Heating expansion valve, 94 First bypass passage, 96 Second bypass passage, 98 Battery cooling circuit pump, 104 Heating circuit pump, 106 Engine cooling circuit, 108 Three-way dialect.

Claims

1. A front air conditioning unit that provides air conditioning for the space in front of the vehicle's passenger compartment, A rear air conditioning unit that provides air conditioning for the rear space of the vehicle's passenger compartment, A refrigeration cycle circuit that distributes and supplies refrigerant to the front air conditioning unit and the rear air conditioning unit, the refrigeration cycle circuit capable of operating in a cooling operation in which the refrigerant supplied to the front air conditioning unit and the rear air conditioning unit is completely liquefied, and in a dehumidifying heating operation in which the refrigerant is in a gas-liquid two-phase state, A heating circuit that generates a high-temperature liquid using a heat source or the refrigerant of 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 system equipped with, Based on the required discharge temperature, which is the control target for the temperature of the air delivered from the front air conditioning unit and the rear air conditioning unit, and the outside temperature, and in the dehumidifying heating operation region in which the refrigeration cycle circuit performs the dehumidifying heating operation, when the front air conditioning unit and the rear air conditioning unit are in operation, and at least one of the front air conditioning unit and the rear air conditioning unit performs bi-level operation, delivering cool air to the upper body of the occupant and warm air to their feet, The refrigeration cycle circuit performs the cooling operation and supplies 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 it to the front air conditioning unit and the rear air conditioning unit. Vehicle air conditioning system.

2. A vehicle air conditioning system according to claim 1, wherein the heat source of the heating circuit is either or both of the engine that drives the vehicle and an electric heater.

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