JP7816992B2 - Vehicle air conditioning system - Google Patents

Description

The present invention relates to a heat pump-type vehicle air conditioning system for use in a vehicle, and in particular to a vehicle air conditioning system with multiple operating modes.

In recent years, hybrid and electric vehicles, which use electric motors to drive their traction motors, have become increasingly common. A known type of vehicle air conditioning system for such vehicles includes a refrigerant circuit connected to a compressor, a radiator (condenser) located in the air flow passage that radiates heat from the refrigerant, a heat absorber (evaporator) located in the air flow passage that absorbs heat from the refrigerant, and an exterior heat exchanger located outside the passenger compartment that radiates or absorbs heat from the refrigerant. The air in the air flow passage exchanges heat with the refrigerant in the radiator or heat absorber, and the air is then supplied to the passenger compartment to heat or cool the passenger compartment.

In such vehicle air conditioning systems, the heat absorber and radiator cool or heat the air passing through the air flow passage, and an air mix damper in the air flow passage adjusts the volume of air blown to the radiator, thereby controlling the outlet temperature of the air supplied to the passenger compartment to a target outlet temperature (see, for example, Patent Document 1).

The air mix damper is controlled based on the air flow rate SW of the air ventilated into the radiator. The air flow rate SW is calculated using an estimated value of the radiator outlet air temperature, which is calculated using a predetermined estimation formula. The vehicle air conditioning system in Patent Document 1 uses a different estimation formula for each operating mode to calculate an appropriate estimate for each operating mode.

JP 2018-65486 A

However, when a vehicle equipped with a vehicle air conditioning system is driven in an environment where the outside air temperature is extremely low (cryogenic environment), the refrigerant cannot absorb heat from the outside air in the exterior heat exchanger, so it is possible to heat the vehicle interior using a hot gas heating mode that uses a hot gas circuit that does not allow refrigerant to pass through the exterior heat exchanger.

In hot gas heating mode, the state of the refrigerant in the refrigerant circuit changes differently than in normal operating mode, resulting in a large deviation between the estimated value (estimated temperature) of the radiator outlet air temperature and the actual outlet air temperature. In this case, the air mix damper is controlled based on the airflow ratio SW calculated from the estimated temperature that deviates from the actual outlet air temperature, making it impossible to accurately control the outlet temperature of the air supplied to the passenger compartment and achieving comfortable air conditioning.

The present invention was made in light of these circumstances, and aims to accurately estimate the outlet air temperature of the radiator and accurately control the temperature of the air blown into the vehicle cabin, even during heating operation using a hot gas circuit, thereby achieving comfortable air conditioning.

The present invention provides a vehicle air conditioning system comprising: a refrigerant circuit including a compressor that compresses refrigerant, a radiator that uses heat from the refrigerant to heat air supplied to the vehicle cabin, and an exterior heat exchanger that exchanges heat between the refrigerant and outside air; and a control device that controls the refrigerant circuit. The refrigerant circuit has a hot gas circuit that causes refrigerant discharged from the compressor to bypass the exterior heat exchanger and flow into the suction side of the compressor via the radiator. The control device is capable of operating a hot gas heating mode in which refrigerant is circulated through the hot gas circuit to heat the vehicle cabin using the heat of the refrigerant compressed by the compressor. In the hot gas heating mode, the control device calculates an estimated value of the radiator outlet air temperature using a correction value obtained based on the saturation temperature calculated from the radiator outlet refrigerant pressure and the radiator inlet side superheat degree or the radiator outlet side superheat degree.

According to the present invention, even during heating operation using a hot gas circuit, the outlet air temperature of the radiator can be accurately estimated, allowing for accurate temperature control of the air blown into the vehicle cabin, thereby achieving comfortable air conditioning.

1 is an explanatory diagram showing a schematic configuration of a vehicle air conditioning system according to an embodiment of the present invention and a flow of refrigerant; 1 is a block diagram showing a schematic configuration of a control device for a vehicle air conditioner according to an embodiment of the present invention; 3A to 3C are explanatory diagrams showing the flow of refrigerant in a refrigerant circuit when each operation mode using a hot gas circuit is performed in the vehicle air conditioner according to the embodiment of the present invention. FIG. 3 is a Mollier diagram showing changes in the state of refrigerant when a hot gas heating mode and a hot gas heating mode are executed in the vehicle air conditioning system according to the embodiment of the present invention. 4 is a Mollier diagram showing a change in state of refrigerant when a battery heating mode is executed in the vehicle air conditioner according to the embodiment of the present invention. FIG. 4 is a saturation temperature curve table showing the relationship between the pressure and the saturation temperature of the refrigerant. 4 is an explanatory diagram showing the flow of refrigerant in a refrigerant circuit when an outside air heat absorption heating mode is performed in the vehicle air conditioner according to the embodiment of the present invention; FIG. 4 is a Mollier diagram showing a change in state of refrigerant when an outside air heat absorption heating mode is performed in the vehicle air conditioner according to the embodiment of the present invention. FIG. 3 is an explanatory diagram showing the flow of refrigerant in a refrigerant circuit when a battery cooling mode is executed in the vehicle air conditioner according to the embodiment of the present invention; FIG.

The following describes in detail the embodiments of the present invention with reference to the drawings. In the following description, the same reference numerals indicate parts with the same functions, and duplicate descriptions within each drawing will be omitted where appropriate.

Figure 1 shows the schematic configuration of a vehicle air conditioner 1 according to an embodiment of the present invention. The vehicle air conditioner 1 can be applied to vehicles such as electric vehicles (EVs) that do not have an engine (internal combustion engine) or so-called hybrid vehicles that use both an engine and an electric motor for driving. Such vehicles are equipped with a battery 55 (e.g., a lithium battery) and are powered by supplying power charged in the battery 55 from an external power source to a motor unit (not shown) that includes a driving motor (electric motor). The vehicle air conditioner 1 is also powered by the battery 55.

The vehicle air conditioner 1 includes a refrigerant circuit R for heat pump operation and a heat medium circuit 60 for adjusting the temperature of the battery 55 as a temperature adjustment target. The heat medium circuit 60 is connected to the refrigerant circuit R so that heat can be exchanged via a temperature adjustment target heat exchanger 64, which will be described later. The vehicle air conditioner 1 performs air conditioning within the vehicle cabin and adjusts the temperature of the battery 55 by selectively executing various operating modes, including air conditioning operations such as heating operation and cooling operation, through heat pump operation using the refrigerant circuit R.

In addition to the battery 55, the heat medium circuit 60 can also regulate the temperature of other devices, such as a motor unit or other heat-generating equipment mounted on the vehicle.

The refrigerant circuit R is composed of a compressor 2 that compresses the refrigerant, an indoor heat exchanger 4 that is located in the air flow passage 3 of the HVAC unit 10 through which air from the vehicle cabin is circulated and ventilated. The indoor heat exchanger 4 is a radiator that dissipates heat from the high-temperature, high-pressure refrigerant discharged from the compressor 2 to heat the air supplied to the vehicle cabin, an outdoor expansion valve 6 that reduces the pressure and expands the refrigerant during heating, an outdoor heat exchanger 7 that exchanges heat between the refrigerant and outside air and functions as a radiator (condenser) that dissipates heat from the refrigerant during cooling and as an evaporator that absorbs heat from the refrigerant during heating, an indoor expansion valve 8 that reduces the pressure and expands the refrigerant, a heat absorber 9 that is located in the air flow passage 3 and that cools the air supplied to the vehicle cabin by having the refrigerant absorb heat from inside and outside the vehicle during cooling and dehumidification, and an accumulator 12, all of which are connected by refrigerant piping 13A-13K.

The outdoor expansion valve 6 and indoor expansion valve 8 are both electronic expansion valves driven by pulse motors (not shown). The opening degree is appropriately controlled between fully closed and fully open depending on the number of pulses applied to the pulse motor. The outdoor expansion valve 6 reduces the pressure and expands the refrigerant that flows out of the indoor heat exchanger 4 and into the outdoor heat exchanger 7 during heating operation or defrosting operation using the outdoor heat exchanger 7. The indoor expansion valve 8 reduces the pressure and expands the refrigerant that flows into the heat absorber 9, and adjusts the amount of heat absorbed by the refrigerant in the heat absorber 9, i.e., the cooling capacity of the passing air.

The refrigerant outlet of the outdoor heat exchanger 7 and the refrigerant inlet of the heat absorber 9 are connected by refrigerant piping 13A. Refrigerant piping 13A is provided with a check valve 18 and an indoor expansion valve 8, in that order from the outdoor heat exchanger 7 side. The check valve 18 is provided on refrigerant piping 13A so that the direction toward the heat absorber 9 is the forward direction. Refrigerant piping 13A branches into refrigerant piping 13B at a position closer to the outdoor heat exchanger 7 than the check valve 18, and also branches into refrigerant piping 13I between the check valve 18 and the indoor expansion valve 8.

Refrigerant pipe 13B, which branches off from refrigerant pipe 13A, is connected to the refrigerant inlet of accumulator 12. Refrigerant pipe 13B is provided with, in order from the outdoor heat exchanger 7 side, a solenoid valve 21 that opens during heating and a check valve 20. Check valve 20 is connected so that the direction toward accumulator 12 is the forward direction. Refrigerant pipe 13B branches off to refrigerant pipe 13C between solenoid valve 21 and check valve 20. Refrigerant pipe 13C, which branches off from refrigerant pipe 13B, is connected to the refrigerant outlet of heat absorber 9. The refrigerant outlet of accumulator 12 is connected to compressor 2 by refrigerant pipe 13D.

The refrigerant outlet of the compressor 2 and the refrigerant inlet of the indoor heat exchanger 4 are connected by refrigerant piping 13E. One end of refrigerant piping 13F is connected to the refrigerant outlet of the indoor heat exchanger 4, and the other end of refrigerant piping 13F branches into refrigerant piping 13G and refrigerant piping 13H just before the outdoor expansion valve 6 (upstream of the refrigerant). One of the branched refrigerant piping 13G is connected to the refrigerant inlet side of the outdoor heat exchanger 7 via the outdoor expansion valve 6. The other branched refrigerant piping 13H is connected between the check valve 18 of refrigerant piping 13A and the indoor expansion valve 8. A solenoid valve 22 is provided upstream of the connection point of refrigerant piping 13H with refrigerant piping 13A. The solenoid valve 22 may be an electronic expansion valve.

Furthermore, refrigerant pipe 13I, branching off from refrigerant pipe 13A, is connected to refrigerant flow path 64A of the heat exchanger 64 to be temperature controlled, and is provided with a chiller expansion valve 72. Chiller expansion valve 72 is an electronic expansion valve driven by a pulse motor (not shown), and its opening is appropriately controlled between fully closed and fully open depending on the number of pulses applied to the pulse motor. Chiller expansion valve 72 decompresses and expands the refrigerant flowing into refrigerant flow path 64A of the heat exchanger 64 to be temperature controlled. One end of refrigerant pipe 13J is connected to the outlet of refrigerant flow path 64A of the heat exchanger 64 to be temperature controlled. The other end of refrigerant pipe 13J is connected to refrigerant pipe 13B near the inlet of accumulator 12.

As a result, refrigerant pipe 13H is connected in parallel to the series circuit of outdoor expansion valve 6, outdoor heat exchanger 7, and check valve 18, bypassing outdoor expansion valve 6, outdoor heat exchanger 7, and check valve 18. Refrigerant pipe 13H and refrigerant pipe 13I form a hot gas circuit that allows refrigerant discharged from compressor 2 to flow to indoor heat exchanger 4, bypassing outdoor heat exchanger 7, and passing through temperature-controlled heat exchanger 64 before flowing into the suction side of compressor 2. Whether or not refrigerant is allowed to flow into refrigerant pipe 13G, i.e., whether or not to use the hot gas circuit, can be selected depending on the opening and closing of solenoid valve 22 provided on refrigerant pipe 13H.

The refrigerant outlet of compressor 2 and the refrigerant suction side of accumulator 12 are connected by refrigerant piping 13K. An electronic expansion valve 24 is provided in refrigerant piping 13K, and by opening electronic expansion valve 24, a bypass circuit can be formed in which refrigerant discharged from compressor 2 is sucked back into compressor 2.

On the air flow passage 3 upstream of the heat absorber 9, an outside air inlet and an inside air inlet are formed (represented by inlet 25 in Figure 1). An inlet switching damper 26 is provided at inlet 25. The inlet switching damper 26 appropriately switches between inside air (air inside the vehicle cabin) and outside air (air outside the vehicle cabin) and introduces the air into the air flow passage 3 through inlet 25. An indoor blower 27 is provided downstream of the inlet switching damper 26 to send the introduced inside air or outside air to the air flow passage 3.

An air mix damper 28 is provided in the air flow passage 3 on the air upstream side of the indoor heat exchanger 4. This adjusts the proportion of air (indoor air and outdoor air) in the air flow passage 3 that flows into the air flow passage 3 and passes through the heat absorber 9 before being ventilated to the indoor heat exchanger 4 and auxiliary heater 23.

As an auxiliary heating means, for example, hot water heated by compressor waste heat can be circulated through a heater core arranged in the air flow passage 3 to heat the blown air.

The heat medium circuit 60 includes a pump 61 for circulating the heat medium through the heat medium circuit 60 and flowing the heat medium to the battery 55, and a temperature-controlled heat exchanger 64, which passes the heat medium through the battery 55, which is the temperature-controlled target, to adjust the temperature of the battery 55.

The heat medium circuit 60 is provided so that the heat medium exchanges heat with the refrigerant circulating in the refrigerant circuit R in the temperature-controlled heat exchanger 64. That is, in the heat medium circuit 60, the heat medium passes through a heat medium flow path 64B of the temperature-controlled heat exchanger 64 and exchanges heat with the refrigerant passing through a refrigerant flow path 64A of the temperature-controlled heat exchanger 64. The heat medium, whose temperature has been controlled by heat exchange with the refrigerant, is circulated through the heat medium circuit 60 by a pump 61, and passes through the battery 55, thereby controlling the temperature of the battery 55.
In this way, the temperature-controlled heat exchanger 64 constitutes a part of the refrigerant circuit R and also constitutes a part of the heat medium circuit 60 .

The heat medium used in the heat medium circuit 60 can be, for example, water, a refrigerant such as HFO-1234yf, a liquid such as a coolant liquid made by adding antifreeze to water, or a gas such as air. In this embodiment, a coolant liquid is used as the heat medium. Also, the battery 55 is surrounded by a jacket structure that allows the heat medium to flow in a heat exchange relationship with the battery 55.

Figure 2 shows the schematic configuration of the control device 100 that controls the vehicle air conditioner 1. When the vehicle air conditioner 1 is installed in a vehicle, the control device 100 is connected to the vehicle controller 35, which controls the overall vehicle, including drive control of the motor unit and charge/discharge control of the battery 55, via an in-vehicle network such as a Controller Area Network (CAN) or a Local Interconnect Network (LIN), so that they can communicate with each other and send and receive information.

The control device 100 and vehicle controller 35 can be implemented, for example, as a computer equipped with a processor such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit), electrical circuits, and storage elements such as RAM (Random Access Memory) or ROM (Read Only Memory).

The following sensors and detectors are connected to the control device 100, and the outputs of these sensors and detectors are input. Note that in the following description, illustrations and descriptions of components not directly related to the operation of the vehicle air conditioner 1 according to this embodiment will be omitted.

Specifically, the control device 100 is connected to an outside air temperature sensor 33 that detects the vehicle's outside air temperature Tam, an HVAC intake temperature sensor 36 that detects the temperature of air drawn into the air flow passage 3 from the intake port 25, an inside air temperature sensor 37 that detects the air temperature inside the vehicle cabin (inside air temperature Tin), an outlet temperature sensor 41 that detects the temperature of air blown into the vehicle cabin from the outlet 29, an indoor heat exchanger inlet temperature sensor 43 that detects the inlet refrigerant temperature Tcxin of the indoor heat exchanger 4, an intake temperature/pressure sensor 46 that detects the intake refrigerant temperature TS and intake refrigerant pressure PS of the compressor 2, an indoor heat exchanger temperature sensor 44 that detects the outlet refrigerant temperature Tci of the indoor heat exchanger 4, an indoor heat exchanger pressure sensor 47 that detects the outlet refrigerant pressure Pci of the indoor heat exchanger 4, and an air conditioning operation unit 53 for setting the set temperature and switching between air conditioning modes.

In addition to the above, the control device 100 is connected to a battery temperature sensor 76 that detects the temperature of the battery 55, and a heat medium temperature sensor 79 that detects the temperature Tw (chiller water temperature) of the heat medium that leaves the heat medium flow path of the temperature-controlled heat exchanger 64 and enters the battery 55. To determine the temperature of the battery 55, either the battery temperature sensor 76 or the heat medium temperature sensor 79 can be used as appropriate.

Meanwhile, the output of the control device 100 is connected to the compressor 2, indoor blower 27, suction switching damper 26, air mix damper 28, outdoor expansion valve 6, indoor expansion valve 8, solenoid valves 21 and 22, electronic expansion valve 24, pump 61, and chiller expansion valve 72. The control device 100 controls these based on the output of each sensor, settings input via the air conditioning operation unit 53, and information from the vehicle controller 35.

With the vehicle air conditioner 1 configured in this way, the optimal operating mode can be selected from multiple operating modes depending on the environment in which the vehicle equipped with the vehicle air conditioner 1 is traveling and the vehicle's condition. For example, when the vehicle is traveling in an extremely low-temperature environment below a predetermined temperature, the exterior heat exchanger 7 cannot absorb heat from the outside air, so the hot gas heating mode is executed, which uses the hot gas circuit to heat the vehicle cabin.

In addition, in extremely low-temperature environments, it becomes necessary to heat the battery 55, so the system can operate in a battery heating mode that uses a hot gas circuit, or a hot gas mode that simultaneously heats the room and the battery. In addition, various other operating modes can be operated, such as an outdoor air heat absorption heating mode that heats the vehicle interior when the outdoor heat exchanger 7 can absorb heat from the outside air, a battery cooling mode that cools the battery 55, and a cooling mode that cools the vehicle interior using air cooled by the heat absorber 9.

In the present embodiment, the operation of the vehicle air conditioner 1 when each operating mode using the hot gas circuit (i.e., in this embodiment, three operating modes: heating mode, battery heating mode, and hot gas mode) is performed will be described below.

Figure 3 shows the flow of refrigerant in the refrigerant circuit R when each operating mode using the hot gas circuit is being performed. In Figure 3, the refrigerant piping through which the refrigerant flows is indicated by a thick line. The hot gas heating mode, battery heating mode, and hot gas mode, which use the hot gas circuit, may differ from one another in terms of the rotation speed of the compressor 2, the amount of refrigerant circulating through the refrigerant circuit R, the amount of heat medium circulating through the heat medium circuit 60, and the flow rate of air passing through the HVAC unit 10, but the flow paths through which the refrigerant circulates or passes in the refrigerant circuit R are the same.

When heating operation is selected by the control device 100 (auto mode) or by manual operation of the air conditioning operation unit 53 (manual mode) and the vehicle is traveling in an extremely low-temperature environment, the control device 100 starts heating operation using the hot gas circuit. The control device 100 closes the outdoor expansion valve 6, the indoor expansion valve 8, and the solenoid valve 21, opens the solenoid valve 22 and the chiller expansion valve 72, and opens the electronic expansion valve 24. This forms a hot gas circuit and a bypass circuit, allowing the refrigerant to circulate.

When the compressor 2 starts operating in this state, part of the refrigerant discharged from the compressor 2 circulates through the hot gas circuit, and the rest circulates through the bypass circuit. That is, part of the refrigerant discharged from the compressor 2 passes through the indoor heat exchanger 4, the solenoid valve 22 and the chiller expansion valve 72, the temperature-controlled heat exchanger 64, and returns to the compressor 2 via the accumulator 12. On the other hand, the rest of the refrigerant discharged from the compressor 2 returns to the compressor 2 via the electronic expansion valve 24 and the accumulator 12.
Below, differences between the operation modes and the state of the refrigerant circulating through the refrigerant circuit R in each operation mode will be described.

(1) Hot Gas Heating Mode In the hot gas heating mode, the control device 100 operates the indoor blower 27 and sets the air mix damper 28 to a state in which the proportion of air blown from the indoor blower 27 that is ventilated through the indoor heat exchanger 4 is adjusted. The control device 100 also does not operate the pump 61 and does not circulate the heat medium through the heat medium circuit 60. In other words, the refrigerant does not exchange heat with the heat medium when passing through the temperature-controlled heat exchanger 64.

FIG. 4 shows a Mollier diagram illustrating the state change of the refrigerant in the hot gas heating mode.
The high-temperature, high-pressure gas refrigerant discharged from the compressor 2 and flowing into the indoor heat exchanger 4 exchanges heat with the air in the air flow passage 3, whereby the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown into the vehicle interior through the air outlet 29 to provide heating. The refrigerant that has exchanged heat in the indoor heat exchanger 4 loses heat to the air, is cooled, and condenses.

After leaving the indoor heat exchanger 4, the condensed refrigerant passes through refrigerant pipes 13F, 13H, 13A, and 13I, passes through the chiller expansion valve 72, and then passes through the temperature-controlled heat exchanger 64. The refrigerant expands in the chiller expansion valve 72 to a low temperature and low pressure, passes through the temperature-controlled heat exchanger 64 without exchanging heat with the heat medium, and flows into the accumulator 12 through refrigerant pipes 13J and 13B.

On the other hand, the high-temperature, high-pressure gas refrigerant discharged from the compressor 2 passes through the refrigerant pipe 13K, is expanded by the electronic expansion valve 24, and flows again into the accumulator 12. That is, the refrigerant liquefied in the indoor heat exchanger 4 and the refrigerant compressed by the compressor 2 and then expanded by the electronic expansion valve 24 flow into the accumulator 12. The refrigerant that has flowed into the accumulator 12 is separated into gas and liquid, and then is sucked into the compressor 2 as gas refrigerant through the refrigerant pipe 13D, repeating this circulation.
(2) Battery Heating Mode In the battery heating mode, the control device 100 does not operate the indoor blower 27, and does not perform heat exchange between the refrigerant and the air in the indoor heat exchanger 4. In other words, the refrigerant only passes through the indoor heat exchanger 4. In addition, the pump 61 is operated to circulate the heat medium in the heat medium circuit 60, and performs heat exchange between the refrigerant and the heat medium in the temperature-controlled heat exchanger 64.

FIG. 5 shows a Mollier diagram illustrating the state change of the refrigerant in the battery heating mode.
The high-temperature, high-pressure gas refrigerant discharged from the compressor 2 and flowing into the indoor heat exchanger 4 passes through without exchanging heat with the air in the air flow passage 3. After leaving the indoor heat exchanger 4, the refrigerant passes through refrigerant pipes 13F, 13H, 13A, and 13I in the state of a high-temperature, high-pressure gas refrigerant, passes through the chiller expansion valve 72, and then passes through the temperature-controlled heat exchanger 64. The refrigerant exchanges heat with a heat medium in the temperature-controlled heat exchanger 64, whereby the heat medium circulating through the heat medium circuit 60 is heated by the refrigerant, and the heated heat medium heats the battery 55. The refrigerant that has exchanged heat in the temperature-controlled heat exchanger 64 loses heat to the heat medium, is cooled, and condenses, and flows into the accumulator 12 through refrigerant pipes 13J and 13B.

Meanwhile, the high-temperature, high-pressure gas refrigerant discharged from compressor 2 travels through refrigerant piping 13K, expands in electronic expansion valve 24, and flows back into accumulator 12. That is, the accumulator 12 receives both refrigerant liquefied in the temperature-controlled heat exchanger 64 and refrigerant compressed in compressor 2 and then expanded in electronic expansion valve 24. The refrigerant that flows into accumulator 12 is separated into gas and liquid, and then repeatedly circulated as gas refrigerant, passing through refrigerant piping 13D and being drawn into compressor 2.

(3) Hot gas mode (operating mode in which hot gas heating and battery heating are performed simultaneously)
In the hot gas mode, the control device 100 operates the indoor blower 27, and the air mix damper 28 adjusts the proportion of air blown from the indoor blower 27 that is ventilated through the indoor heat exchanger 4. The control device 100 also operates the pump 61 to circulate the heat medium through the heat medium circuit 60, and heat exchange between the refrigerant and the heat medium occurs in the temperature-controlled heat exchanger 64.

A Mollier diagram showing the change in state of the refrigerant in the hot gas mode is similar to the Mollier diagram showing the change in state of the refrigerant in the hot gas heating mode in FIG. 4, and therefore is not shown in the figure.
The high-temperature, high-pressure gas refrigerant discharged from the compressor 2 and flowing into the indoor heat exchanger 4 exchanges heat with the air in the air flow passage 3, whereby the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown into the vehicle interior through the air outlet 29 to provide heating. The refrigerant that has exchanged heat in the indoor heat exchanger 4 loses heat to the air, is cooled, and condenses.

After leaving the indoor heat exchanger 4, the condensed refrigerant passes through refrigerant pipes 13F, 13H, 13A, and 13I, passes through the chiller expansion valve 72, and then passes through the temperature-controlled heat exchanger 64. The refrigerant exchanges heat with the heat medium in the temperature-controlled heat exchanger 64, heating the heat medium circulating through the heat medium circuit 60, and the heated heat medium heats the battery 55. The refrigerant that has exchanged heat in the temperature-controlled heat exchanger 64 loses heat to the heat medium, is cooled, and condenses, and flows into the accumulator 12 via refrigerant pipes 13J and 13B.

Meanwhile, the high-temperature, high-pressure gas refrigerant discharged from compressor 2 travels through refrigerant piping 13K, expands in electronic expansion valve 24, and flows back into accumulator 12. That is, the accumulator 12 receives refrigerant liquefied in the indoor heat exchanger 4 and the temperature-controlled heat exchanger 64, and refrigerant compressed in compressor 2 and then expanded in electronic expansion valve 24. The refrigerant that flows into accumulator 12 is separated into gas and liquid, and then repeatedly circulated as gas refrigerant, being drawn into compressor 2 via refrigerant piping 13D.

In addition, while examples have been described in which the bypass circuit is also used in each of the operating modes using the hot gas circuit described above, it is not necessary to use the bypass circuit, and each operating mode may be performed using only the hot gas circuit. When the bypass circuit is used, the refrigerant compressed by the compressor 2 to a high temperature and pressure is returned to the compressor 2 via the bypass circuit, allowing for additional power to be added to the compressor 2. This has the advantage that air at the desired temperature can be supplied to the passenger compartment more quickly than when the bypass circuit is not used, and the heat medium in the heat medium circuit 60 can be heated to the desired temperature more quickly.

(Regarding temperature control of air blown into the vehicle cabin)
When the hot gas heating mode and hot gas mode are executed, the control device 100 adjusts the volume of air passed through the indoor heat exchanger 4 by the air mix damper 28, and controls the compressor 2 to control heating in the indoor heat exchanger 4. In this way, the control device 100 controls the temperature of the air blown into the vehicle compartment from the air outlet 29 to be the target blown air temperature TAO.

Here, the control device 100 controls the opening and closing of the air mix damper 28 based on the air volume ratio SW.

The air volume ratio SW is calculated by the following formula (1).
SW=(TAO-Te)/(Theat-Te)...(1)
Here, TAO is the target outlet temperature of the air blown into the vehicle cabin from the air outlet 29, Te is the outlet air temperature of the heat absorber 9, and Theat is the estimated value of the outlet air temperature of the indoor heat exchanger 4 (hereinafter referred to as the "estimated heating temperature").

The estimated heating temperature Theat can be calculated by the following equation (2).
Theat = (INTL_TH * Theat0+Tau_TH * Theatz)/(Tau_TH+INTL_TH)...(2)
Here, INTL_TH is the calculation period (constant), Tau_TH is the time constant of the first-order lag, TheaT0 is the estimated heating temperature TheaT before the first-order lag calculation, and TheaTz is the previous value of the estimated heating temperature TheaT.

When calculating the estimated heating temperature Theat, the time constant Tau_TH and steady-state value Theat0 are changed depending on the operating mode, and the above-mentioned formula (2) is made to differ depending on the operating mode, thereby calculating and estimating the estimated heating temperature Theat.

In particular, in the hot gas heating mode and hot gas mode, which perform heating operation using a hot gas circuit, the refrigerant becomes superheated, as shown in the Mollier diagram in Figure 4. Therefore, in the hot gas heating mode and hot gas mode, the control device 100 calculates the estimated heating temperature Theat using the saturation temperature calculated from the outlet refrigerant pressure Pci of the indoor heat exchanger 4 and a correction value obtained based on the inlet side superheat or outlet side superheat of the indoor heat exchanger 4.

Specifically, the steady-state value Theat0 in equation (1) is changed as shown in equation (3) below, and the estimated heating temperature Theat is calculated by using the changed steady-state value Theat0 in equation (1) as a correction value.
Theat0=THsatu+TH_HOS+TH_OFFSET…(3)
Here, THsaturation temperature is calculated from the outlet refrigerant pressure Pci of the indoor heat exchanger 4, and can be calculated by referring to a saturation temperature curve table. Fig. 6 shows the saturation temperature curve table indicating the relationship between the refrigerant pressure and the saturation temperature.

TH_HOS is a value obtained based on the inlet superheat degree SHcxin or outlet superheat degree SHcxout of the indoor heat exchanger 4, and TH_OFFSET is an offset value. TH_HOS can be the sum of the inlet superheat degree SHcxin and outlet superheat degree SHcxout of the indoor heat exchanger 4, or the inlet superheat degree SHcxin.

The inlet superheat degree SHcxin is obtained by subtracting the saturation temperature THsat from the inlet refrigerant temperature Tcxin of the indoor heat exchanger 4. The outlet superheat degree SHcxout is obtained by subtracting the saturation temperature THsat from the outlet refrigerant temperature Tci of the indoor heat exchanger 4.

In addition, the control device 100 may calculate an estimated value of the outlet air temperature of the indoor heat exchanger 4 using a correction value obtained based on the inlet refrigerant temperature of the indoor heat exchanger 4, instead of the saturation temperature calculated from the outlet refrigerant pressure Pci of the indoor heat exchanger 4 and a correction value obtained based on the inlet superheat degree or outlet superheat degree of the indoor heat exchanger 4. In other words, the estimated heating temperature Theat0 can be calculated by changing the steady-state value Theat0 in the above formula (1) to the sum of the inlet refrigerant temperature Tcxin of the indoor heat exchanger 4 and the offset value, and using the changed steady-state value Theat0 as a correction value in formula (1).

As described above, in the vehicle air conditioning system 1 according to this embodiment, the control device 100 uses a correction value based on the degree of superheat of the refrigerant when calculating the estimated heating temperature Theat, which is an estimate of the outlet air temperature. This reduces deviation from the actual outlet air temperature of the indoor heat exchanger 4 that occurs due to changes in the state of the refrigerant during heating using the hot gas circuit, and allows for accurate estimation of the outlet air temperature of the indoor heat exchanger 4. Therefore, the air volume ratio SW can be calculated using the estimated heating temperature Theat, which has high estimation accuracy, allowing for accurate temperature control of the air blown into the vehicle cabin and comfortable air conditioning.
therefore,

As reference examples of other operation modes that can be performed in the vehicle air conditioner 1 according to this embodiment shown in FIG. 1, an outside air heat absorption heating mode and a battery cooling mode will be described below.
(Outside air heat absorption heating mode)
Fig. 7 shows the flow (thick line) of refrigerant in the refrigerant circuit R in the outdoor air heat absorption heating mode. Fig. 8 is a Mollier diagram showing the state change of the refrigerant in the outdoor air heat absorption heating mode.
When the control device 100 executes the outdoor air heat absorption heating mode, it opens the outdoor expansion valve 6 and the solenoid valve 21, and fully closes the solenoid valve 22, the indoor expansion valve 8, the electronic expansion valve 24, and the chiller expansion valve 72. It operates the compressor 2 and the indoor blower 27, and sets the air mix damper 28 to a state in which it adjusts the proportion of air blown out from the indoor blower 27 that is ventilated to the indoor heat exchanger 4.

As a result, the high-temperature, high-pressure gas refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4. In the indoor heat exchanger 4, heat is exchanged between the air in the air flow passage 3 and the high-temperature, high-pressure refrigerant. In other words, the air in the air flow passage 3 is heated by the refrigerant, and the heated air is blown out from the air outlet 29 into the vehicle cabin, thereby heating the vehicle.

Meanwhile, the refrigerant passing through the indoor heat exchanger 4 is cooled and condensed as heat is absorbed by the air passing through the air flow passage 3. After leaving the indoor heat exchanger 4, the liquefied refrigerant passes through refrigerant pipes 13F and 13G and reaches the outdoor expansion valve 6. The refrigerant is depressurized by the outdoor expansion valve 6 before flowing into the outdoor heat exchanger 7. The refrigerant that flows into the outdoor heat exchanger 7 evaporates and draws heat (absorbs heat) from outside air that flows in as the vehicle moves or from outside air ventilated by an outdoor fan (not shown). In other words, the refrigerant circuit R functions as a heat pump.

The low-temperature refrigerant leaving the outdoor heat exchanger 7 flows through refrigerant pipes 13A and 13B, solenoid valve 21, and check valve 20 into accumulator 12. After gas and liquid separation in accumulator 12, the gas refrigerant passes through refrigerant pipe 13D and is drawn into compressor 2, repeating this cycle.

(Battery cooling mode)
Figure 9 shows the flow of refrigerant in the refrigerant circuit R in the battery cooling mode. In Figure 9, the refrigerant piping through which the refrigerant flows is indicated by a thick line. The Mollier diagram showing the change in state of the refrigerant in the battery cooling mode is the same as the Mollier diagram showing the change in state of the refrigerant in the outside air heat absorption heating mode shown in Figure 8, so it is not shown in the figure.
When the control device 100 executes the battery cooling mode, it opens the outdoor expansion valve 6 and the chiller expansion valve 72, and fully closes the solenoid valves 21 and 22, the indoor expansion valve 8, and the electronic expansion valve 24. Then, it operates the compressor 2 without operating the indoor blower 27.

As a result, the high-temperature, high-pressure refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 4, but only passes through it. The refrigerant that leaves the indoor heat exchanger 4 passes through refrigerant pipes 13F and 13G and reaches the outdoor expansion valve 6. After being decompressed by the outdoor expansion valve 6, the refrigerant flows into the outdoor heat exchanger 7. The refrigerant that flows into the outdoor heat exchanger 7 is air-cooled by outside air that flows in as the vehicle is moving, or by outside air blown in by an outdoor fan (not shown), and condenses and liquefies.

The refrigerant leaving the outdoor heat exchanger 7 flows through the refrigerant pipe 13A, check valve 18, and chiller expansion valve 72 into the temperature-controlled heat exchanger 64, where it evaporates. The heat absorption effect at this time cools the heat medium circulating through the heat medium circuit 60.

The refrigerant evaporated in the temperature-controlled heat exchanger 64 travels through refrigerant pipe 13J to the accumulator 12, and then travels through refrigerant pipe 13D to be sucked into the compressor 2, repeating this cycle. The heat medium cooled in the temperature-controlled heat exchanger 64 is pumped by the pump 61 to the battery 55, where it cools the battery 55.

The above describes in detail embodiments of the present invention with reference to the drawings, but the specific configuration is not limited to these embodiments, and design changes that do not deviate from the gist of the present invention are also included in the present invention.

1: Vehicle air conditioning system, 2: Compressor, 3: Air flow passage, 4: Indoor heat exchanger, 6: Outdoor expansion valve, 7: Outdoor heat exchanger, 8: Indoor expansion valve, 9: Heat absorber, 10: HVAC unit, 12: Accumulator, 13A-13K: Refrigerant piping, 18, 20: Check valve, 21, 22: Solenoid valve, 24: Electronic expansion valve, 25: Intake port, 26: Intake switching damper, 27: Indoor blower, 28: Air mix damper, 29: Air outlet, 55: Battery, 60: Heat transfer medium circuit, 61: Pump, 64: Temperature-controlled heat exchanger, 64A: Refrigerant flow path, 64B: Heat transfer medium flow path, 72: Chiller expansion valve, 100: Control device

Claims (8)

a refrigerant circuit including a compressor that compresses a refrigerant, a radiator that heats air to be supplied into the vehicle interior using heat from the refrigerant, and an exterior heat exchanger that exchanges heat between the refrigerant and outside air;
a control device for controlling the refrigerant circuit;
the refrigerant circuit includes a hot gas circuit that guides the refrigerant discharged from the compressor to the radiator , bypasses the outdoor heat exchanger, and flows from the radiator into the suction side of the compressor;
The control device
a hot gas heating mode can be executed in which a refrigerant is circulated through the hot gas circuit to heat the vehicle interior using heat of the refrigerant compressed by the compressor;
In the hot gas heating mode, the vehicle air conditioning system calculates an estimated value of the outlet air temperature of the radiator using a saturation temperature calculated from the outlet refrigerant pressure of the radiator and a correction value obtained based on the inlet side superheat degree or the outlet side superheat degree of the radiator. The vehicle air conditioning system of claim 1, wherein the control device uses the estimated value to calculate the air volume ratio to be ventilated through the radiator. A vehicle air conditioning system according to claim 1 or 2, wherein the correction value is the sum of the saturation temperature, the inlet superheat, and an offset value. The vehicle air conditioning system of claim 1 or 2, wherein the correction value is the sum of the saturation temperature, the inlet superheat degree, the outlet superheat degree, and an offset value. A vehicle air conditioning system according to any one of claims 1 to 4, wherein the inlet superheat degree is the difference between the inlet refrigerant temperature of the radiator and the saturation temperature. A vehicle air conditioning system according to any one of claims 1 to 5, wherein the outlet-side superheat degree is the difference between the outlet refrigerant temperature of the radiator and the saturation temperature. a refrigerant circuit including a compressor that compresses a refrigerant, a radiator that heats air to be supplied into the vehicle interior using heat from the refrigerant, and an exterior heat exchanger that exchanges heat between the refrigerant and outside air;
a control device for controlling the refrigerant circuit;
the refrigerant circuit includes a hot gas circuit that guides the refrigerant discharged from the compressor to the radiator , bypasses the outdoor heat exchanger, and flows from the radiator into the suction side of the compressor;
The control device
a hot gas heating mode can be executed in which a refrigerant is circulated through the hot gas circuit to heat the vehicle interior using heat from the refrigerant compressed by the compressor;
In the hot gas heating mode, an estimated value of the outlet air temperature of the radiator is calculated using a correction value obtained based on the inlet refrigerant temperature of the radiator. A vehicle air conditioning system according to any one of claims 1 to 7, wherein the hot gas circuit includes a bypass circuit that connects the discharge side and suction side of the compressor and allows the refrigerant discharged from the compressor to be sucked back into the compressor.