Heat pump air conditioning system

Abstract

A heat pump air conditioning system comprises: a compressor; a first heat exchanger; a first refrigerant flow path provided with a first expansion valve and a second heat exchanger; a second refrigerant flow path provided with a first solenoid valve; a third refrigerant flow path provided with a second solenoid valve; a fourth refrigerant flow path provided with a second expansion valve and a third heat exchanger; a fifth refrigerant flow path provided with a third expansion valve and a fourth heat exchanger; and a liquid storage tank; a control unit is also provided, the control unit controls at least any one of the first to second expansion valves and the first to second solenoid valves to operate a plurality of different heating modes; in the plurality of different heating modes, the control unit compares a waste heat recovery characterization value of the heat pump air conditioning system with a first threshold value and a second threshold value greater than the first threshold value, and when the waste heat recovery function is turned off, the waste heat recovery function is turned on only when the waste heat recovery characterization value is greater than the second threshold value, and when the waste heat recovery function is turned on, the waste heat recovery function is turned off only when the waste heat recovery characterization value is less than the first threshold value.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile air conditioning, and in particular to a heat pump air conditioning system. Background Art

[0002] When the automobile heat pump air conditioner is heating in winter, as the ambient temperature decreases, it becomes more difficult for the system to absorb heat from the environment, which will lead to problems such as insufficient maximum heating capacity and reduced energy efficiency. In the prior art, it is known to add a waste heat recovery function to the heat pump air conditioner system, which effectively improves the maximum heating capacity and heating efficiency of the system by absorbing the heat of the ambient temperature and the waste heat of the strong electrical system components and / or the battery side at the same time.

[0003] However, if waste heat recovery is implemented when the system heat load is low or the waste heat generated by the high-voltage components or batteries is low, the oil accumulation will occur due to the low branch flow rate, which will reduce the oil circulation rate of the system. The frequency of the system triggering the compressor oil return protection strategy will increase. Under the compressor oil return protection strategy, the system flushes the accumulated lubricating oil back to the compressor by concentrating the refrigerant into the flow path where the oil accumulation phenomenon occurs. The application of this oil return protection strategy will lead to a decrease in system efficiency, and the system efficiency when waste heat is recovered may be lower than the system efficiency when waste heat is not recovered. Summary of the invention

[0004] Problems to be solved by the invention:

[0005] In view of the above problems, the purpose of the present invention is to provide a heat pump air-conditioning system, which can control the opening and closing of the waste heat recovery function according to the size of the waste heat recovery characterization value in the system under various operating modes, to ensure that the heating efficiency of the system after the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off and to prevent repeated fluctuations in the system.

[0006] Technical means to solve the problem:

[0007] To solve the above problems, a heat pump air conditioning system as one aspect of the present invention is provided.

[0008] include:

[0009] compressor;

[0010] a first heat exchanger;

[0011] A first refrigerant flow path having a first expansion valve and a second heat exchanger located downstream of the first expansion valve;

[0012] A second refrigerant flow path provided with a first solenoid valve;

[0013] A third refrigerant flow path provided with a second solenoid valve;

[0014] A fourth refrigerant flow path having a second expansion valve and a third heat exchanger disposed downstream of the second expansion valve;

[0015] A fifth refrigerant flow path having a third expansion valve and a fourth heat exchanger disposed downstream thereof; and

[0016] Fluid storage tank;

[0017] The heat pump air conditioning system is further provided with a control unit, and the heat pump air conditioning system controls at least one of the first to second expansion valves and the first to second solenoid valves through the control unit to switch different connection modes between the first refrigerant flow path and the fourth refrigerant flow path, thereby operating a plurality of different heating modes;

[0018] When the heat pump air-conditioning system operates the multiple different heating modes, the control unit controls to turn on or off the waste heat recovery function that absorbs heat from the vehicle-mounted heating components through the fourth heat exchanger in the following manner: compare the waste heat recovery characterization value of the heat pump air-conditioning system with a pre-set first threshold and a second threshold that is greater than the first threshold; when the waste heat recovery function is in the off state, the waste heat recovery function is turned on only when the waste heat recovery characterization value is greater than the second threshold; when the waste heat recovery function is in the on state, the waste heat recovery function is turned off only when the waste heat recovery characterization value is less than the first threshold.

[0019] Effect of the invention:

[0020] The present invention can ensure that the heating efficiency of the system after the waste heat recovery function is turned on is always higher than the efficiency when the waste heat recovery function is turned off and prevent repeated fluctuations of the heat pump air conditioning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a heat pump air conditioning system according to an embodiment of the present invention;

[0022] Figure 2 Shows Figure 1 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the normal heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on;

[0023] Figure 3 is a schematic diagram showing a waste heat recovery control strategy based on a heat load characterization value;

[0024] Figure 4 is a schematic diagram showing a waste heat recovery control strategy based on a waste heat characterization value;

[0025] Figure 5 Shows Figure 1The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the parallel dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on;

[0026] Figure 6 Shows Figure 1 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the series dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on;

[0027] Figure 7 Shows Figure 1 The refrigerant flow state of the heat pump air conditioning system shown in the figure when the evaporator is in a single dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on;

[0028] Figure 8 is a schematic structural diagram of a heat pump air conditioning system according to another embodiment of the present invention;

[0029] Fig. 9 Shows Figure 8 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the normal heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on;

[0030] Fig.10 Shows Figure 8 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the parallel dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on;

[0031] Fig.11 Shows Figure 8 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the series dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on;

[0032] Fig.12 Shows Figure 8 The refrigerant flow state of the heat pump air conditioning system shown in the figure when the evaporator is in a single dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on;

[0033] Fig.13 yes Figure 1 A schematic structural diagram of a modified example of the heat pump air conditioning system shown;

[0034] Explanation of symbols:

[0035] 100, 100A, heat pump air conditioning system with liquid storage tank (liquid storage tank heat pump system); 200, heat pump air conditioning system with gas-liquid separator (gas-liquid separator heat pump system); 1, compressor; 2, 22, first heat exchanger; 3, first expansion valve; 4, second heat exchanger; 5, second expansion valve; 6, third heat exchanger; 7, liquid storage tank; 8, gas-liquid separator; 9, pump; 10, 23, PTC heater; 11, heater core; 12a, first solenoid valve; 12b, second solenoid valve; 12c, third solenoid valve; 13, third expansion valve; 14, 24, fourth heat exchanger; 15, pump; 16, battery (on-board heating component); 17, pump; 18, strong electric system components (on-board heating component); 19, refrigerant temperature sensor; 20, refrigerant pressure sensor; 21, cooling water temperature sensor. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and the following embodiments. It should be understood that the accompanying drawings and the following embodiments are only used to illustrate the present invention rather than to limit the present invention.

[0037] Disclosed herein is a heat pump air conditioning system that controls the on and off of a waste heat recovery function according to the size of a waste heat recovery characterization value in the system under multiple operating modes to ensure that the heating efficiency of the system after the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off and to prevent repeated fluctuations in the system.

[0038] The heat pump air conditioning system is a vehicle air conditioning device installed in the vehicle. It realizes functions such as heating, cooling, and heating and dehumidification of the vehicle interior by controlling the flow state of the refrigerant in the circuit.

[0039] Figure 1 is a schematic diagram of a heat pump air conditioning system according to an embodiment of the present invention, specifically, Figure 1 A heat pump air conditioning system with a liquid storage tank (hereinafter referred to as a "liquid storage tank heat pump system") 100 is shown. Figure 1 As shown, a compressor 1 is provided in the heat pump air conditioning system, and the compressor 1 may be an electric compressor. Refrigerant circulates in the heat pump air conditioning system. The compressor 1 inhales low-temperature and low-pressure gas refrigerant from the suction port, compresses the refrigerant through the piston driven by the motor, and then discharges high-temperature and high-pressure gas refrigerant from the discharge port. The refrigerant is mixed with lubricating oil for lubricating the compressor 1, and the two circulate together in the heat pump air conditioning system under the action of the compressor 1.

[0040] A first heat exchanger 2 is connected to the outlet of the compressor 1, i.e., the downstream side of the compressor 1. The first heat exchanger 2 is a refrigerant-cooling water heat exchanger, and in this embodiment is a water-cooled condenser, which is arranged in the engine compartment. A first cooling water circuit is also provided in the liquid storage tank heat pump system 100, and the first cooling water circuit includes a pump 9 for pumping the cooling water circulation and a warm air core 11 for performing heat exchange with the air entering the vehicle cabin. The high-temperature and high-pressure refrigerant performs heat exchange with the cooling water in the first cooling water circuit at the first heat exchanger 2, and the cooling water is heated by the refrigerant, and the heated cooling water heats the air entering the vehicle cabin in the warm air core 11. In addition, a PTC heater 10 for auxiliary heating of the cooling water can be provided in the first cooling water circuit, and the heat energy generated by the PTC heater 10 is transferred to the vehicle cabin through the warm air core 11.

[0041] In the heat pump air conditioning system, the first to fifth refrigerant flow paths are respectively connected to the downstream side of the first heat exchanger 2. In this embodiment, the flow conditions of the refrigerant in the heat pump air conditioning system can be controlled by selectively connecting or blocking these flow paths, thereby realizing different working modes to meet the thermal management requirements of the automobile.

[0042] Specifically, a first expansion valve 3 and a second heat exchanger 4 closer to the downstream side than the first expansion valve 3 are sequentially arranged on the first flow path of the refrigerant along the refrigerant flow direction. The first expansion valve 3 is an electrically variable throttling mechanism, i.e., an electronic expansion valve, which can change the opening according to a control signal output by a control unit described later, and when fully closed, blocks the first flow path of the refrigerant and does not allow the refrigerant to pass through. The second heat exchanger 4 is an outdoor heat exchanger located outside the vehicle room, which contacts the external air, such as the wind when the vehicle is running, so that the refrigerant flowing out of the first expansion valve 3 exchanges heat with the external air to absorb environmental heat.

[0043] The second refrigerant flow path is provided with a first solenoid valve 12 a , which is a low-pressure solenoid valve capable of opening and closing the second refrigerant flow path under the control of the control unit.

[0044] like Figure 1 As shown, the first refrigerant flow path and the second refrigerant flow path are connected in the following manner: the inlet of the first expansion valve 3 is connected to the outlet side of the first heat exchanger 2, the outlet of the second heat exchanger 4 is connected to the inlet of the liquid storage tank 7 through the first solenoid valve 12a, and the outlet of the liquid storage tank 7 is connected to the suction port of the compressor 1 through a pipeline. In addition, in the liquid storage tank heat pump system 100, a third refrigerant flow path is also branched from the first refrigerant flow path, and the details are described later.

[0045] The fourth refrigerant flow path is provided with a second expansion valve 5 and a third heat exchanger 6 which is closer to the downstream side than the second expansion valve 5 in sequence along the refrigerant flow direction. The second expansion valve 5 is an electrically variable throttling mechanism which can adjust the opening according to the control signal output by the control unit, and blocks the fourth refrigerant flow path when fully closed. The third heat exchanger 6 is provided in the housing of the air conditioning unit in the vehicle interior, so that the low-temperature and low-pressure refrigerant discharged from the second expansion valve 5 exchanges heat with the air supplied to the vehicle interior, thereby absorbing heat and cooling the air, thereby dehumidifying or cooling the vehicle interior.

[0046] The third expansion valve 13 and the fourth heat exchanger 14 closer to the downstream side than the third expansion valve 13 are sequentially arranged on the fifth flow path of the refrigerant along the refrigerant flow direction. Among them, the third expansion valve 13 is an electrically variable throttling mechanism that can adjust the opening according to the control signal output by the control unit, and blocks the fifth flow path of the refrigerant when fully closed. In this embodiment, the fourth heat exchanger 14 is a water-cooled refrigerant-cooling water heat exchanger that performs heat exchange with the second cooling water circuit described later.

[0047] In the liquid storage tank heat pump system 100, cooling water circulates in the second cooling water circuit, and the cooling water cools the vehicle-mounted heat-generating components by heat exchange with the vehicle-mounted heat-generating components, which include a battery 16 and a strong electric system component 18 such as an electric motor, an inverter, and a vehicle-mounted charger. In this embodiment, these high-temperature cooling waters flow in from the cooling water inlet of the fourth heat exchanger 14, and heat exchange with the low-temperature refrigerant flowing in from the refrigerant inlet in the fourth heat exchanger 14 to become low-temperature cooling water and be discharged from the cooling water outlet. Under the action of pumps 15 and 17, the cooling waters flow into the battery 16 and the strong electric system components respectively for heat exchange. Thus, the fourth heat exchanger 14 can function as a battery cooler or a waste heat recovery device.

[0048] like Figure 1 As shown, in this embodiment, the fourth refrigerant flow path and the fifth refrigerant flow path are connected to the circuit in parallel with the second refrigerant flow path. In other words, the two flow paths are respectively connected in parallel to the two sides of the first electromagnetic valve 12a. More specifically, the outlet of the second heat exchanger 4 is not only connected to the liquid storage tank 7 through the first electromagnetic valve 12a, but also connected to the inlet of the second expansion valve 5 of the fourth refrigerant flow path and the inlet of the third expansion valve 13 of the fifth refrigerant flow path through a bypass pipeline. A check valve is provided on the bypass pipeline, which allows the refrigerant to flow from the outlet of the second heat exchanger 4 to the inlet of the second expansion valve 5 and the third expansion valve 13, and prohibits its reverse flow. On the other hand, the refrigerant outlets of the third heat exchanger 6 and the fourth heat exchanger 14 are respectively connected to the liquid storage tank 7, so that the refrigerant after heat exchange returns to the compressor 1 through the liquid storage tank 7.

[0049] As described above, a third refrigerant flow path is branched from the first refrigerant flow path, and the third refrigerant flow path is set to have one end located between the first heat exchanger 2 and the first expansion valve 3, and the other end located on the pipeline connecting the outlet of the second heat exchanger 4 and the inlet of the second expansion valve 5 and the third expansion valve 13. A second solenoid valve 12b is provided on the third refrigerant flow path, and the second solenoid valve 12b is a high-pressure solenoid valve that can open and close the third refrigerant flow path under the control of the control unit described later. In other words, when the second solenoid valve 12b is opened, a part of the refrigerant flowing out of the first heat exchanger 2 can be diverted to the fourth refrigerant flow path and / or the fifth refrigerant flow path via the third refrigerant flow path.

[0050] In addition, the liquid storage tank heat pump system 100 also includes a control unit (not shown). The control unit may be, for example, a microcomputer having a memory such as a ROM and a RAM and a CPU, and the CPU executes a program stored in the ROM. The control unit issues control instructions to each expansion valve, each solenoid valve, etc. in the liquid storage tank heat pump system 100 to control the opening and closing conditions of each valve to achieve different thermal management modes, and adjusts the opening size of each valve to meet the workload under these thermal management modes.

[0051] In the liquid storage tank heat pump system 100 with the above structure, the control unit controls at least one of the expansion valves and the solenoid valves to change the circuit structure, so that the refrigerant circulates in the liquid storage tank heat pump system 100 with different circuit structures under the action of the compressor 1 to operate a variety of heating modes including ordinary heating mode, parallel dehumidification heating mode, series dehumidification heating mode and evaporator single dehumidification heating mode. In these heating modes, the waste heat recovery function for recycling the waste heat generated by the vehicle-mounted heating components can be turned on or off. Figures 1 to 7 Describes more than 100 heating modes of the liquid storage tank heat pump system and the corresponding waste heat recovery control function.

[0052] [Normal heating mode]

[0053] Figure 2 Shows Figure 1 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the normal heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on. Figure 2 As shown in (a) and (b), the normal heating mode is a working mode in which the liquid storage tank heat pump system 100 heats the cooling water in the first cooling water circuit through the first heat exchanger 2 to heat the vehicle interior using the heater core 11, and absorbs ambient heat through the second heat exchanger 4. Specifically, Figure 1As shown, the control unit opens the first electromagnetic valve 12a to connect the second refrigerant flow path and closes the second expansion valve 5 to block the fourth refrigerant flow path, thereby operating the normal heating mode. In the normal heating mode, the control unit turns on the waste heat recovery function by opening the second electromagnetic valve 12b and the third expansion valve 13, that is, by connecting the third refrigerant flow path and the fifth refrigerant flow path, and turns off the waste heat recovery function by closing at least one of the second electromagnetic valve 12b and the third expansion valve 13, that is, by blocking at least one of the third refrigerant flow path or the fifth refrigerant flow path.

[0054] Specifically, if Figure 2 As shown in (a), when the liquid storage tank heat pump system 100 operates in the normal heating mode with the waste heat recovery function of at least one of the second solenoid valve 12b and the third expansion valve 13 closed, the compressor 1, the first heat exchanger 2, the first refrigerant flow path and the second refrigerant flow path are connected in series in sequence, and the refrigerant circulates in the liquid storage tank heat pump system 100 in the following form: the low-temperature and low-pressure gas refrigerant is compressed by the compressor 1 to become a high-temperature and high-pressure gas and is discharged from the discharge port, flows into the first heat exchanger 2 to release heat to the cooling water in the first cooling water circuit to become a medium-temperature and high-pressure liquid refrigerant, and becomes a low-temperature two-phase refrigerant after being throttled by the first expansion valve 3 in the refrigerant first flow path. Then, when passing through the second heat exchanger 4, the refrigerant evaporates and absorbs environmental heat to become a low-pressure refrigerant close to a gas state, which flows into the refrigerant second flow path, passes through the first solenoid valve 12a, flows into the liquid storage tank 7, and returns to the compressor 1.

[0055] When the system determines that waste heat recovery is required, such as Figure 2 As shown in (b), the control unit opens the second solenoid valve 12b and the third expansion valve 13, and the liquid storage tank heat pump system 100 operates in the normal heating mode with the waste heat recovery function turned on. At this time, the flow path formed by the first refrigerant flow path and the second refrigerant flow path in series and the flow path formed by the third refrigerant flow path and the fifth refrigerant flow path in series form a parallel connection, and the medium-temperature and high-pressure liquid refrigerant flowing out of the first heat exchanger 2 is divided into the first refrigerant flow path and the third refrigerant flow path between the first heat exchanger 2 and the first expansion valve 3. On the one hand, the refrigerant flowing into the first refrigerant flow path passes through the first expansion valve 3 and the second heat exchanger 4 in sequence as described above, and then becomes a low-pressure refrigerant passing through the first solenoid valve 12a. On the other hand, since the fourth refrigerant flow path is blocked by the closing of the second expansion valve 5, and the check valve prevents the refrigerant from flowing from the third refrigerant flow path through the bypass pipeline into the second refrigerant flow path, the refrigerant flowing into the third refrigerant flow path enters the fifth refrigerant flow path after passing through the second solenoid valve 12b, and throttles and expands to become a low-temperature and low-pressure two-phase refrigerant when passing through the third expansion valve 13, and then evaporates in the fourth heat exchanger 14 as a waste heat recovery device to absorb the waste heat of the vehicle-mounted heating components and become a low-pressure refrigerant close to the gas state. This refrigerant merges with the other refrigerant passing through the first solenoid valve 12a and returns to the compressor 1 through the liquid storage tank 7.

[0056] According to the above structure, under the control of the control unit, the tank heat pump system 100 can operate in the normal heating mode with the waste heat recovery function turned on or off, thereby selectively recovering waste heat according to the vehicle thermal management requirements while performing normal heating in the vehicle.

[0057] (Waste heat recovery control strategy)

[0058] As described above, in the heat pump air conditioning system, the control unit will turn on or off the waste heat recovery function of absorbing heat from the vehicle-mounted heating components through the fourth heat exchanger 14 according to the vehicle thermal management requirements in the normal heating mode. When the heat pump air conditioning system turns on the waste heat recovery function, the fifth flow path of the refrigerant is connected in parallel to the heat pump air conditioning system to divert the refrigerant. During the operation of the system, according to experimental data, when the refrigerant flow rate of any of the two parallel heat exchangers (the second heat exchanger 4 as the outdoor heat exchanger and the fourth heat exchanger 14 as the waste heat recovery device) is continuously less than 20-40 kg / h for a period of time, the problem of compressor oil-poor lock may occur. In order to prevent the occurrence of compressor oil-poor lock, the system will start the compressor oil return protection strategy. During the operation of the oil return protection strategy, the system produces fluctuations and the efficiency is reduced. The system efficiency when the waste heat is recovered may be lower than the system efficiency when the waste heat is not recovered. In order to avoid this situation, the present invention sets a waste heat recovery characterization value and a specified value for the heat pump air-conditioning system for predicting the system efficiency when recovering waste heat from vehicle-mounted heating components. The control unit compares the specified value with the real-time waste heat recovery characterization value of the heat pump air-conditioning system to determine whether to recover waste heat, and the waste heat recovery function is turned on or off by opening or closing the solenoid valve and / or expansion valve on the upstream side of the fourth heat exchanger 14 serving as a waste heat recoverer.

[0059] On the other hand, if the control unit immediately turns on the waste heat recovery function when the waste heat recovery characteristic value is higher than the specified value, and immediately turns off the waste heat recovery function when the waste heat recovery characteristic value is lower than the specified value, then the heat pump air-conditioning system will repeatedly turn on and off the waste heat recovery function (such as repeatedly turning on and off the expansion valve and solenoid valve) due to changes in the system heat load or changes in the amount of waste heat generated by the vehicle's heating components, thereby greatly reducing the life of the valve and causing repeated fluctuations in the system.

[0060] Therefore, the present invention further sets a first threshold and a second threshold for the prescribed value of the waste heat recovery characterization value. The first threshold is the threshold of the waste heat recovery characterization value when the waste heat recovery function is turned on so that the heating efficiency of the heat pump air conditioning system begins to exceed the threshold of the waste heat recovery characterization value when the waste heat recovery function is not turned on, and the second threshold is the threshold of the waste heat recovery characterization value when the waste heat recovery function is turned on so that the heating efficiency of the heat pump air conditioning system is higher than when the waste heat recovery function is not turned on, taking into account the two factors of the operating life of the third expansion valve 13 and the heat loss of the waste heat of the vehicle-mounted heating components.

[0061] The experimental results show that the refrigerant flow rate of the second heat exchanger 4 as an outdoor heat exchanger is related to the system heat load, and the refrigerant flow rate of the fourth heat exchanger 14 as a waste heat recovery device is related to the waste heat. Therefore, in the present invention, the waste heat recovery characterization value may include two signals: the heat load characterization value and the waste heat characterization value.

[0062] On the one hand, when the thermal load of the system is low (regardless of the amount of waste heat of the entire vehicle), the flow rate of the first flow path of the refrigerant provided with the second heat exchanger 4 may be lower than 20-40 kg / h. In order to prevent the system from operating in a state with an efficiency lower than that of the normal heating mode, the present invention can adopt a strategy for waste heat recovery control based on a thermal load characterization value used to characterize the thermal load of the vehicle. Figure 3 is a schematic diagram showing a waste heat recovery control strategy based on a heat load characterization value.

[0063] Since it is difficult to calculate the vehicle thermal load in real time, the compressor speed is selected as the thermal load characterization value to characterize the size of the vehicle thermal load, and a first threshold and a second threshold greater than the first threshold are set for the compressor speed as the thermal load characterization value. However, the present invention is not limited to this, and a physical quantity positively correlated with the compressor speed, such as the power consumption of the compressor 1, may also be used as the thermal load characterization value.

[0064] The control unit is in normal heating mode. Figure 3 As shown, the compressor speed as the heat load characterization value is compared with the preset first threshold and second threshold. When the heat pump air conditioning system is in a state where the waste heat recovery function is turned off, when the compressor speed is higher than the first threshold, even if the vehicle side allows waste heat recovery, the air conditioning side does not actually perform waste heat recovery. Only when the compressor speed is higher than the second threshold, the air conditioning side performs waste heat recovery, that is, Figure 3 As shown by the middle arrow, when the heat pump air conditioning system is in the state of turning off the waste heat recovery function, it will not continue to recover waste heat until the compressor speed is higher than the second threshold value, and then open the corresponding solenoid valve and expansion valve to start the waste heat recovery function. On the other hand, when the heat pump air conditioning system is in the state of turning on the waste heat recovery function, it will not stop the waste heat recovery when the compressor speed is lower than the second threshold value. Only when the compressor speed is lower than the first threshold value will the air conditioning side actually stop the waste heat recovery, that is, Figure 3 As shown by the middle arrow, the heat pump air conditioning system, when the waste heat recovery function is turned on, continues to recover waste heat until the compressor speed is lower than the first threshold, and then closes the corresponding solenoid valve and expansion valve to stop the waste heat recovery function. According to experimental data, the first threshold can be 1000-1800rpm, and the second threshold can be 2200-3000rpm.

[0065] On the other hand, when the waste heat amount of the whole vehicle is low (regardless of the heat load of the system), the flow rate of the fifth flow path of the refrigerant provided with the fourth heat exchanger 14 may be lower than 20-40 kg / h. In order to prevent the system from operating at an efficiency lower than that of ordinary heating, the present invention can adopt a waste heat recovery control strategy based on a waste heat characterization value used to characterize the waste heat generated by the vehicle-mounted heating components. Figure 4 is a schematic diagram showing a waste heat recovery control strategy based on a waste heat value characterization value.

[0066] Since it is difficult to calculate the waste heat in real time, the difference between the cooling water temperature at any point between the cooling water inlet and the cooling water outlet of the fourth heat exchanger 14 as a waste heat recovery device and the saturated refrigerant temperature flowing through the fourth heat exchanger 14 (hereinafter sometimes referred to as "temperature difference") is selected as the waste heat characterization value to characterize the amount of waste heat, and a first threshold value and a second threshold value greater than the first threshold value are set for the temperature difference as the waste heat characterization value. However, the present invention is not limited to this. In the circuit of the waste heat recovery device using refrigerant direct cooling, such as the gas-liquid separator heat pump system 200 and the liquid storage tank heat pump system 100A described later, the difference between the temperature of the vehicle-mounted heating component and the saturated refrigerant temperature flowing through the fourth heat exchangers 14 and 24 can also be used as the waste heat characterization value.

[0067] As an example of calculating the temperature difference, Figure 1 As shown, a refrigerant temperature sensor 19 and a refrigerant pressure sensor 20 can be set on the downstream side of the fourth heat exchanger 14 in the fifth refrigerant flow path, that is, at the refrigerant outlet of the fourth heat exchanger 14, and a cooling water temperature sensor 21 can be set at the cooling water outlet of the fourth heat exchanger 14 in the second cooling water circuit. The saturated refrigerant temperature flowing through the fourth heat exchanger 14 can be calculated based on the measurement value of the refrigerant pressure sensor 20 or obtained by taking the smaller of the refrigerant inlet temperature and the refrigerant outlet temperature of the fourth heat exchanger 14.

[0068] The control unit is in normal heating mode. Figure 4As shown, the temperature difference as the waste heat characterization value is compared with the preset first threshold and second threshold. When the heat pump air conditioning system is in the state of turning off the waste heat recovery function, when the temperature difference is higher than the first threshold, even if the vehicle side allows waste heat recovery, the air conditioning side does not actually perform waste heat recovery. Only when the temperature difference is higher than the second threshold, the air conditioning side performs waste heat recovery, that is, Figure 3 As shown by the middle arrow, when the heat pump air conditioning system is in the state of turning off the waste heat recovery function, it will not continue to recover waste heat until the temperature difference is higher than the second threshold value, and then open the corresponding solenoid valve and expansion valve to start the waste heat recovery function. On the other hand, when the heat pump air conditioning system is in the state of turning on the waste heat recovery function, it will not stop the waste heat recovery when the temperature difference is lower than the second threshold value. Only when the temperature difference is lower than the first threshold value will the air conditioning side actually stop the waste heat recovery, that is, Figure 3 As shown by the middle arrow, the heat pump air conditioning system, when the waste heat recovery function is turned on, continues to recover waste heat until the temperature difference is lower than the first threshold, and then closes the corresponding solenoid valve and expansion valve to stop the waste heat recovery function. According to experimental data, the first threshold can be 0-5°C, and the second threshold can be 6-11°C.

[0069] By setting two thresholds for the waste heat recovery characterization value, a buffer area can be formed between opening and closing the waste heat recovery function, thereby ensuring that the heating efficiency of the heat pump air-conditioning system when the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off, while effectively preventing the reduction in valve life caused by repeated opening and closing of valves and fluctuations in the heat pump air-conditioning system.

[0070] Furthermore, the present invention can also implement the above-mentioned waste heat recovery control strategy by comprehensively considering the heat load characterization value and the waste heat characterization value. Specifically, when the waste heat recovery function of the heat pump air-conditioning system is in the off state, the control unit controls the waste heat recovery function to be converted from the off state to the on state only when the heat load characterization value is greater than the second threshold value of the heat load characterization value and the waste heat characterization value is greater than the second threshold value of the waste heat characterization value. When the waste heat recovery function of the heat pump air-conditioning system is in the on state, the control unit controls the waste heat recovery function to be converted from the on state to the off state only when the heat load characterization value is less than the first threshold value of the heat load characterization value or the waste heat characterization value is less than the first threshold value of the waste heat characterization value. In this way, it is possible to take into account the conditions of low system heat load and low waste heat of the whole vehicle, ensuring that the heat pump air-conditioning system always operates at optimal efficiency.

[0071] [Parallel dehumidification and heating mode]

[0072] Figure 5 Shows Figure 1The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the parallel dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on. Figure 5 As shown in (a) and (b), the parallel dehumidification and heating mode is an operating mode in which the liquid storage tank heat pump system 100 heats the vehicle interior through the first heat exchanger 2, absorbs ambient heat through the second heat exchanger 4, and dehumidifies the vehicle interior through the third heat exchanger 6. In this parallel dehumidification and heating mode, Figure 1 As shown, the control unit opens the first solenoid valve 12a to connect the second refrigerant flow path and opens the second solenoid valve 12b to connect the third refrigerant flow path, and opens or closes the waste heat recovery function by opening or closing the third expansion valve 13, that is, by connecting or blocking the fifth refrigerant flow path.

[0073] Specifically, if Figure 5 As shown in (a), when the liquid storage tank heat pump system 100 operates in the parallel dehumidification and heating mode with the third expansion valve 13 closed, that is, the waste heat recovery function is closed, the compressor 1, the first heat exchanger 2, the first refrigerant flow path and the second refrigerant flow path are connected in series in sequence, and the flow path formed by the first refrigerant flow path and the second refrigerant flow path in series and the flow path formed by the third refrigerant flow path and the fourth refrigerant flow path in series form a parallel connection, and the refrigerant circulates in the liquid storage tank heat pump system 100 in the following form: the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 releases heat in the first heat exchanger 2 to become a medium-temperature and high-pressure liquid refrigerant, and the refrigerant is divided into the first refrigerant flow path and the third refrigerant flow path between the first heat exchanger 2 and the first expansion valve 3. On the one hand, the refrigerant flowing into the first refrigerant flow path passes through the first expansion valve 3 and the second heat exchanger 4 in sequence and becomes a low-pressure refrigerant passing through the first solenoid valve 12a. On the other hand, since the fifth refrigerant flow path is blocked by the closing of the third expansion valve 13 and the check valve prevents the refrigerant from flowing from the third refrigerant flow path to the second refrigerant flow path through the bypass pipe, the refrigerant flowing into the third refrigerant flow path enters the fourth refrigerant flow path after passing through the second solenoid valve 12b, and throttles and expands to become a low-temperature and low-pressure two-phase refrigerant when passing through the second expansion valve 5, and then heat exchanges with the interior air in the third heat exchanger 6 to dehumidify it. The refrigerant merges with the other refrigerant passing through the first solenoid valve 12a and returns to the compressor 1 through the liquid storage tank 7.

[0074] When the system determines that waste heat recovery is required, such as Figure 5As shown in (b), the control unit operates the parallel dehumidification and heating mode with the third expansion valve 13 open, that is, the waste heat recovery function is turned on. At this time, the flow path formed by the first refrigerant flow path and the second refrigerant flow path in series, the flow path formed by the third refrigerant flow path and the fourth refrigerant flow path in series, and the fifth refrigerant flow path are connected in parallel. The refrigerant flowing into the third refrigerant flow path is split again after passing through the second solenoid valve 12b, and flows into the fourth refrigerant flow path and the fifth refrigerant flow path respectively. The refrigerant flowing into the fourth refrigerant flow path passes through the second expansion valve 5 as described above, and is dehumidified by heat exchange with the air in the vehicle interior in the third heat exchanger 6. The refrigerant flowing into the fifth refrigerant flow path is throttled and expanded when passing through the third expansion valve 13 to become a low-temperature and low-pressure two-phase refrigerant, and then absorbs the waste heat of the vehicle-mounted heating components in the fourth heat exchanger 14 as a waste heat recovery device to become a low-pressure refrigerant close to the gas state. The refrigerant is combined with the refrigerant flowing out of the fourth refrigerant flow path and the refrigerant passing through the first electromagnetic valve 12 a and then returns to the compressor 1 through the liquid storage tank 7 .

[0075] According to the above structure, under the control of the control unit, the liquid storage tank heat pump system 100 can operate in the parallel dehumidification and heating mode with the waste heat recovery function turned on or off, thereby selectively recovering waste heat according to the vehicle thermal management requirements while performing parallel dehumidification and heating in the vehicle. Figure 3 , Figure 4 The waste heat recovery control strategy is executed in that way, thereby ensuring that the heating efficiency of the heat pump air-conditioning system when the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off, and effectively preventing the reduction in valve life and fluctuations in the heat pump air-conditioning system caused by repeated opening and closing of valves. The waste heat recovery control strategy is the same as the waste heat recovery control strategy in the normal heating mode, so its description is omitted.

[0076] [Series dehumidification and heating mode]

[0077] Figure 6 Shows Figure 1 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the series dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on. Figure 6 As shown in (a) and (b), the series dehumidification and heating mode is an operating mode in which the liquid storage tank heat pump system 100 heats the vehicle interior through the first heat exchanger 2, absorbs ambient heat through the second heat exchanger 4, and dehumidifies the vehicle interior through the third heat exchanger 6. In this series dehumidification and heating mode, Figure 1As shown, the control unit controls the throttling of the first expansion valve 3 and the second expansion valve 5, and closes the first solenoid valve 12a to block the second flow path of the refrigerant, closes the second solenoid valve 12b to block the third flow path of the refrigerant, and turns on or off the waste heat recovery function by opening or closing the third expansion valve 13, that is, by connecting or blocking the fifth flow path of the refrigerant.

[0078] Specifically, if Figure 6 As shown in (a), when the liquid storage tank heat pump system 100 operates in the series dehumidification and heating mode with the third expansion valve 13 closed, that is, the waste heat recovery function is closed, the compressor 1, the first heat exchanger 2, the first refrigerant flow path and the fourth refrigerant flow path are connected in series in sequence, and the refrigerant circulates in the liquid storage tank heat pump system 100 in the following form: the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 releases heat in the first heat exchanger 2 to become a medium-temperature and high-pressure liquid refrigerant that flows into the first refrigerant flow path, the refrigerant passes through the first expansion valve 3 and the second heat exchanger 4 in sequence to become a medium-pressure refrigerant and flows into the fourth refrigerant flow path, and when passing through the second expansion valve 5, it is throttled and expanded to become a low-temperature and low-pressure two-phase refrigerant, and then it exchanges heat with the interior air in the third heat exchanger 6 to dehumidify it, and then returns to the compressor 1 through the liquid storage tank 7.

[0079] When the system determines that waste heat recovery is required, such as Figure 6 As shown in (b), the control unit operates the series dehumidification and heating mode in a state where the third expansion valve 13 is opened, that is, the waste heat recovery function is turned on. At this time, on the basis that the compressor 1, the first heat exchanger 2, the first refrigerant flow path and the fourth refrigerant flow path are connected in series in sequence, the fifth refrigerant flow path is connected in parallel with the fourth refrigerant flow path. After the refrigerant flows out of the second heat exchanger 4, it is divided into the fourth refrigerant flow path and the fifth refrigerant flow path through a bypass pipeline provided with a check valve. On the one hand, the medium-pressure refrigerant flowing into the fourth refrigerant flow path is throttled and expanded to become a low-temperature and low-pressure two-phase refrigerant when passing through the second expansion valve 5 as described above, and the air in the vehicle interior is dehumidified in the third heat exchanger 6. On the other hand, the refrigerant flowing into the fifth refrigerant flow path is throttled and expanded to become a low-temperature and low-pressure two-phase refrigerant when passing through the third expansion valve 13, and then absorbs the waste heat of the vehicle-mounted heating components in the fourth heat exchanger 14 as a waste heat recovery device to become a low-pressure refrigerant close to the gas state. The refrigerant is combined with the refrigerant flowing out of the fourth refrigerant flow path and then returns to the compressor 1 through the liquid storage tank 7 .

[0080] According to the above structure, under the control of the control unit, the liquid storage tank heat pump system 100 can operate in the series dehumidification and heating mode with the waste heat recovery function turned on or off, thereby selectively recovering waste heat according to the vehicle thermal management requirements while performing series dehumidification and heating in the vehicle. Figure 3 , Figure 4The waste heat recovery control strategy is executed in that way, thereby ensuring that the heating efficiency of the heat pump air-conditioning system when the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off, and effectively preventing the reduction in valve life and fluctuations in the heat pump air-conditioning system caused by repeated opening and closing of valves. The waste heat recovery control strategy is the same as the waste heat recovery control strategy in the normal heating mode, so its description is omitted.

[0081] [Evaporator single dehumidification and heating mode]

[0082] Figure 7 Shows Figure 1 The refrigerant flow state of the heat pump air conditioning system shown in the figure when the evaporator is in the dehumidification and heating mode alone. (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on. Figure 7 As shown in (a) and (b), the evaporator-only dehumidification and heating mode is an operating mode in which the liquid storage tank heat pump system 100 heats the vehicle interior through the first heat exchanger 2 and performs dehumidification through the third heat exchanger 6 as an evaporator. In this dehumidification and heating mode, Figure 1 As shown, the control unit closes the first expansion valve 3 and the first solenoid valve 12a to block the first refrigerant flow path and the second refrigerant flow path and opens the second solenoid valve 12b to connect the third refrigerant flow path, and turns on or off the waste heat recovery function by opening or closing the third expansion valve 13, that is, by connecting or blocking the fifth refrigerant flow path.

[0083] Specifically, if Figure 7 As shown in (a), when the liquid storage tank heat pump system 100 operates in the evaporator single dehumidification and heating mode with the third expansion valve 13 closed, that is, the waste heat recovery function is closed, the compressor 1, the first heat exchanger 2, the refrigerant third flow path and the refrigerant fourth flow path are connected in series in sequence, and the refrigerant circulates in the liquid storage tank heat pump system 100 in the following form: the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 releases heat in the first heat exchanger 2 to become a medium-temperature and high-pressure liquid refrigerant that flows into the refrigerant third flow path, the refrigerant flows into the refrigerant fourth flow path after passing through the second solenoid valve 12b, and is throttled and expanded when passing through the second expansion valve 5 to become a low-temperature and low-pressure two-phase refrigerant, and then exchanges heat with the interior air in the third heat exchanger 6 to dehumidify it, and then returns to the compressor 1 through the liquid storage tank 7.

[0084] When the system determines that waste heat recovery is required, such as Figure 7As shown in (b), the control unit operates the evaporator single dehumidification and heating mode in a state where the third expansion valve 13 is opened, that is, the waste heat recovery function is turned on. At this time, on the basis that the compressor 1, the first heat exchanger 2, the third refrigerant flow path and the fourth refrigerant flow path are connected in series in sequence, the fifth refrigerant flow path and the fourth refrigerant flow path are connected in parallel. After passing through the second solenoid valve 12b, the refrigerant is divided into the fourth refrigerant flow path and the fifth refrigerant flow path. On the one hand, the high-pressure refrigerant flowing into the fourth refrigerant flow path is throttled and expanded to become a low-temperature and low-pressure two-phase refrigerant when passing through the second expansion valve 5 as described above, and dehumidifies the air in the vehicle interior in the third heat exchanger 6. On the other hand, the refrigerant flowing into the fifth refrigerant flow path is throttled and expanded to become a low-temperature and low-pressure two-phase refrigerant when passing through the third expansion valve 13, and then absorbs the waste heat of the vehicle-mounted heating components in the fourth heat exchanger 14 as a waste heat recovery device to become a low-pressure refrigerant close to the gas state. The refrigerant merges with the refrigerant flowing out of the fourth refrigerant flow path and returns to the compressor 1 through the liquid storage tank 7.

[0085] According to the above structure, under the control of the control unit, the liquid storage tank heat pump system 100 can operate the evaporator dehumidification and heating mode with the waste heat recovery function turned on or off, thereby selectively recovering waste heat according to the vehicle thermal management requirements while performing evaporator dehumidification and heating in the vehicle. Figure 3 , Figure 4 The waste heat recovery control strategy is executed in that way, thereby ensuring that the heating efficiency of the heat pump air-conditioning system when the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off, and effectively preventing the reduction in valve life and fluctuations in the heat pump air-conditioning system caused by repeated opening and closing of valves. The waste heat recovery control strategy is the same as the waste heat recovery control strategy in the normal heating mode, so its description is omitted.

[0086] Figure 8 is a schematic structural diagram of a heat pump air conditioning system according to another embodiment of the present invention, specifically, Figure 8 A heat pump air conditioning system with a gas-liquid separator (hereinafter referred to as "gas-liquid separator heat pump system") 200 is shown. A compressor 1 is provided in the gas-liquid separator heat pump system 200, and a first heat exchanger 2 is connected to the outlet of the compressor 1, that is, the downstream side of the compressor 1, and the first to seventh refrigerant flow paths are respectively connected to the downstream side of the first heat exchanger 2. In this embodiment, the flow conditions of the refrigerant in the heat pump air conditioning system can be controlled by selectively connecting or blocking these flow paths, thereby realizing different working modes to meet the thermal management requirements of the automobile.

[0087] Specifically, in the gas-liquid separator heat pump system 200, the compressor 1, the first heat exchanger 2, the sixth refrigerant flow path, the first refrigerant flow path, and the second refrigerant flow path are sequentially arranged in series. The first expansion valve 3 and the second heat exchanger 4 closer to the downstream side than the first expansion valve 3 are sequentially arranged on the first refrigerant flow path along the refrigerant flow direction, the first solenoid valve 12a is arranged on the second refrigerant flow path, and the third solenoid valve 12c is arranged on the sixth refrigerant flow path.

[0088] A third refrigerant flow path with a second solenoid valve 12b is forked between the first heat exchanger 2 and the third solenoid valve 12c, and the other end of the third refrigerant flow path is connected to the inlet of the gas-liquid separator 8, that is, the gas phase of the gas-liquid separator 8. A refrigerant branch is forked between the second heat exchanger 4 and the first solenoid valve 12a, and the other end of the refrigerant branch is connected to the inlet of the gas-liquid separator 8 together with the third refrigerant flow path. A check valve is provided on the refrigerant branch, which allows the refrigerant to flow from the outlet of the second heat exchanger 4 to the inlet of the gas-liquid separator 8 and prevents its reverse flow.

[0089] A seventh refrigerant flow path is branched between the third solenoid valve 12c and the first expansion valve 3, and the other end thereof is connected to the outlet of the gas-liquid separator 8, i.e., the liquid phase of the gas-liquid separator 8. A check valve is provided on the seventh refrigerant flow path, which allows the liquid refrigerant to flow from the outlet of the gas-liquid separator 8 to the inlet of the first expansion valve 3 and prevents the reverse flow.

[0090] In this embodiment, a fourth refrigerant flow path and a fifth refrigerant flow path are branched from the seventh refrigerant flow path. A second expansion valve 5 and a third heat exchanger 6 closer to the downstream side than the second expansion valve 5 are sequentially arranged on the fourth refrigerant flow path along the refrigerant flow direction, and a third expansion valve 13 and a fourth heat exchanger 14 closer to the downstream side than the third expansion valve 13 are sequentially arranged on the fifth refrigerant flow path along the refrigerant flow direction. The fourth refrigerant flow path and the fifth refrigerant flow path circulate refrigerant in parallel in the form that the inlet side of the second expansion valve 5 and the inlet side of the third expansion valve 13 are respectively connected to the seventh refrigerant flow path, and the outlet side of the third heat exchanger 6 and the outlet side of the fourth heat exchanger 14 are respectively connected to the suction port of the compressor 1.

[0091] In addition, the gas-liquid separator heat pump system 200 also includes a control unit (not shown). The control unit issues control instructions to each expansion valve, each solenoid valve, etc. in the gas-liquid separator heat pump system 200 to control the opening and closing conditions of each valve to achieve different thermal management modes, and adjusts the opening size of each valve to meet the workload under these thermal management modes.

[0092] In the gas-liquid separator heat pump system 200 with the above structure, the control unit controls at least one of the expansion valves and the solenoid valves to change the circuit structure, so that the refrigerant circulates in the gas-liquid separator heat pump system 200 with different circuit structures under the action of the compressor 1 to operate a variety of different heating modes including ordinary heating mode, parallel dehumidification heating mode, series dehumidification heating mode and evaporator single dehumidification heating mode. In these heating modes, the waste heat recovery function for recycling the waste heat generated by the vehicle's heating components can be turned on or off. Figures 9 to 12 Describes more than 200 heating modes of the gas-liquid separator heat pump system and the waste heat recovery control function in these heating modes.

[0093] [Normal heating mode]

[0094] Fig. 9 Shows Figure 8 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the normal heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on. Fig. 9 As shown in (a) and (b), the control unit opens the first solenoid valve 12a to connect the second refrigerant flow path, opens the second solenoid valve 12b to connect the third refrigerant flow path, closes the third solenoid valve 12c to block the sixth refrigerant flow path, and closes the second expansion valve 5 to block the fourth refrigerant flow path, thereby operating the normal heating mode. In the normal heating mode, the control unit turns on the waste heat recovery function by opening the third expansion valve 13, that is, by connecting the fifth refrigerant flow path, and turns off the waste heat recovery function by closing the third expansion valve 13, that is, by blocking the fifth refrigerant flow path.

[0095] Specifically, if Fig. 9 As shown in (a), when the gas-liquid separator heat pump system 200 operates in the normal heating mode with the waste heat recovery function of the third expansion valve 13 closed, the compressor 1, the first heat exchanger 2, the third refrigerant flow path, the gas-liquid separator 8, the seventh refrigerant flow path, the first refrigerant flow path and the second refrigerant flow path are connected in series in sequence, and the refrigerant circulates in the liquid storage tank heat pump system 100 in the following form: the low-temperature and low-pressure gas refrigerant is compressed by the compressor 1 to become a high-temperature and high-pressure gas and is discharged from the discharge port, flows into the first heat exchanger 2 to release heat and become a medium-temperature and high-pressure liquid refrigerant, flows into the gas-liquid separator 8 through the third refrigerant flow path for gas-liquid separation, and the liquid refrigerant flowing out of the gas-liquid separator 8 flows into the first refrigerant flow path through the seventh refrigerant flow path, becomes a low-temperature two-phase refrigerant after being throttled by the first expansion valve 3 in the first refrigerant flow path, and then evaporates when passing through the second heat exchanger 4 to absorb environmental heat and become a low-pressure refrigerant close to the gas state. The refrigerant flows into the second refrigerant flow path and returns to the compressor 1 after passing through the first solenoid valve 12a.

[0096] When the system determines that waste heat recovery is required, such as Fig. 9 As shown in (b), the control unit opens the third expansion valve 13, and the gas-liquid separator heat pump system 200 operates in the normal heating mode with the waste heat recovery function turned on. At this time, the seventh refrigerant flow path, the flow path formed by the first refrigerant flow path and the second refrigerant flow path in series, and the fifth refrigerant flow path form a parallel connection, and the liquid refrigerant flowing out of the gas-liquid separator 8 is diverted to the fifth refrigerant flow path on the seventh refrigerant flow path. On the one hand, the refrigerant flowing into the first refrigerant flow path passes through the first expansion valve 3 and the second heat exchanger 4 in sequence as described above, and then becomes a low-pressure refrigerant and passes through the first solenoid valve 12a. On the other hand, the refrigerant flowing into the fifth refrigerant flow path is throttled and expanded when passing through the third expansion valve 13 to become a low-temperature and low-pressure two-phase refrigerant, and then in the fourth heat exchanger 14 as a waste heat recovery device, the refrigerant evaporates and absorbs the waste heat of the vehicle-mounted heating components to become a low-pressure refrigerant close to the gas state. The refrigerant merges with the other refrigerant passing through the first solenoid valve 12a and returns to the compressor 1.

[0097] According to the above structure, under the control of the control unit, the gas-liquid separator heat pump system 200 can operate in the normal heating mode with the waste heat recovery function turned on or off, thereby selectively recovering waste heat according to the vehicle thermal management requirements while performing normal heating in the vehicle. Figure 3 , Figure 4 The waste heat recovery control strategy is executed in that way, thereby ensuring that the heating efficiency of the heat pump air-conditioning system when the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off, and effectively preventing the reduction in valve life and fluctuations in the heat pump air-conditioning system caused by repeated opening and closing of valves. The waste heat recovery control strategy is the same as the waste heat recovery control strategy in the normal heating mode of the liquid storage tank heat pump system 100, so its description is omitted.

[0098] [Parallel dehumidification and heating mode]

[0099] Fig.10 Shows Figure 8 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the parallel dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on. Fig.10As shown in (a) and (b), the control unit opens the first solenoid valve 12a to connect the second refrigerant flow path, opens the second solenoid valve 12b to connect the third refrigerant flow path, closes the third solenoid valve 12c to block the sixth refrigerant flow path, and throttles the second expansion valve 5 to connect the fourth refrigerant flow path, thereby operating the parallel dehumidification and heating mode. In the parallel dehumidification and heating mode, the control unit turns on the waste heat recovery function by opening the third expansion valve 13, that is, by connecting the fifth refrigerant flow path, and turns off the waste heat recovery function by closing the third expansion valve 13, that is, by blocking the fifth refrigerant flow path.

[0100] Specifically, if Fig.10 As shown in (a), when the gas-liquid separator heat pump system 200 operates in a parallel dehumidification and heating mode with the waste heat recovery function of the third expansion valve 13 closed, the compressor 1, the first heat exchanger 2, the third refrigerant flow path, the gas-liquid separator 8, the seventh refrigerant flow path, the first refrigerant flow path and the second refrigerant flow path are connected in series in sequence, and the flow path formed by the seventh refrigerant flow path, the first refrigerant flow path and the second refrigerant flow path in series and the fourth refrigerant flow path form a parallel connection, and the refrigerant circulates in the gas-liquid separator heat pump system 200 in the following form: the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 releases heat in the first heat exchanger 2 to become a medium-temperature and high-pressure liquid refrigerant, flows into the gas-liquid separator 8 through the third refrigerant flow path for gas-liquid separation, and the liquid refrigerant flowing out of the gas-liquid separator 8 is diverted to the first refrigerant flow path and the fourth refrigerant flow path on the seventh refrigerant flow path. On the one hand, the refrigerant flowing into the first refrigerant flow path passes through the first expansion valve 3 and the second heat exchanger 4 in sequence, and then becomes a low-pressure refrigerant and passes through the first solenoid valve 12a. On the other hand, since the fifth refrigerant flow path is blocked due to the closure of the third expansion valve 13, the refrigerant flowing in the seventh refrigerant flow path is diverted into the fourth refrigerant flow path, and throttles and expands when passing through the second expansion valve 5 to become a low-temperature and low-pressure two-phase refrigerant, and then heat exchanges with the air in the vehicle interior in the third heat exchanger 6 to dehumidify it. The refrigerant merges with the other refrigerant that passes through the first solenoid valve 12a and returns to the compressor 1.

[0101] When the system determines that waste heat recovery is required, such as Fig.10As shown in (b), the control unit opens the third expansion valve 13, and the gas-liquid separator heat pump system 200 operates in parallel dehumidification and heating mode with the waste heat recovery function turned on. At this time, the seventh refrigerant flow path, the flow path formed by the first refrigerant flow path and the second refrigerant flow path in series, the fourth refrigerant flow path, and the fifth refrigerant flow path are connected in parallel, and the liquid refrigerant flowing out of the gas-liquid separator 8 is diverted to the fourth refrigerant flow path and the fifth refrigerant flow path on the seventh refrigerant flow path. On the one hand, the refrigerant flowing into the first refrigerant flow path passes through the first expansion valve 3 and the second heat exchanger 4 in sequence as described above, and then becomes a low-pressure refrigerant passing through the first solenoid valve 12a. On the other hand, the refrigerant flowing into the fourth refrigerant flow path is throttled and expanded when passing through the second expansion valve 5 to become a low-temperature and low-pressure two-phase refrigerant, and then heat-exchanged with the air in the vehicle interior in the third heat exchanger 6 to dehumidify it. On the third aspect, the refrigerant flowing into the fifth refrigerant flow path is throttled and expanded to become a low-temperature and low-pressure two-phase refrigerant when passing through the third expansion valve 13, and then evaporates in the fourth heat exchanger 14 as a waste heat recovery device to absorb the waste heat of the vehicle-mounted heating components and become a low-pressure refrigerant close to the gas state. The above three refrigerants merge and return to the compressor 1.

[0102] According to the above structure, under the control of the control unit, the gas-liquid separator heat pump system 200 can operate in the parallel dehumidification and heating mode with the waste heat recovery function turned on or off, thereby selectively recovering waste heat according to the vehicle thermal management requirements while performing parallel dehumidification and heating in the vehicle. Figure 3 , Figure 4 The waste heat recovery control strategy is executed in that way, thereby ensuring that the heating efficiency of the heat pump air-conditioning system when the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off, and effectively preventing the reduction in valve life and fluctuations in the heat pump air-conditioning system caused by repeated opening and closing of valves. The waste heat recovery control strategy is the same as the waste heat recovery control strategy in the normal heating mode of the liquid storage tank heat pump system 100, so its description is omitted.

[0103] [Series dehumidification and heating mode]

[0104] Fig.11 Shows Figure 8 The refrigerant flow state of the heat pump air conditioning system shown in the figure when executing the series dehumidification and heating mode, (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on. Fig.11As shown in (a) and (b), the control unit closes the first solenoid valve 12a to block the second refrigerant flow path, closes the second solenoid valve 12b to block the third refrigerant flow path, opens the third solenoid valve 12c to connect the sixth refrigerant flow path, and throttles the second expansion valve 5 to connect the fourth refrigerant flow path, thereby operating the series dehumidification and heating mode. In the series dehumidification and heating mode, the control unit turns on the waste heat recovery function by opening the third expansion valve 13, that is, by connecting the fifth refrigerant flow path, and turns off the waste heat recovery function by closing the third expansion valve 13, that is, by blocking the fifth refrigerant flow path.

[0105] Specifically, if Fig.11 As shown in (a), when the gas-liquid separator heat pump system 200 operates in a series dehumidification and heating mode with the waste heat recovery function of the third expansion valve 13 closed, the compressor 1, the first heat exchanger 2, the sixth refrigerant flow path, the first refrigerant flow path, the refrigerant branch, the gas-liquid separator 8 and the fourth refrigerant flow path are connected in series in sequence, and the refrigerant circulates in the gas-liquid separator heat pump system 200 in the following form: the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 releases heat in the first heat exchanger 2 to become a medium-temperature and high-pressure liquid refrigerant, and passes through the refrigerant The sixth flow path flows into the first refrigerant flow path, and is throttled by the first expansion valve 3 in the first refrigerant flow path to become a low-temperature two-phase refrigerant. Then, when passing through the second heat exchanger 4, the refrigerant evaporates and absorbs environmental heat to become a medium-pressure refrigerant, and then flows into the gas-liquid separator 8 through the refrigerant branch for gas-liquid separation. The liquid refrigerant flowing out of the gas-liquid separator 8 flows into the fourth refrigerant flow path, and is throttled and expanded when passing through the second expansion valve 5 to become a low-temperature and low-pressure two-phase refrigerant. Afterwards, it exchanges heat with the air in the vehicle interior in the third heat exchanger 6 to dehumidify it, and then returns to the compressor 1.

[0106] When the system determines that waste heat recovery is required, such as Fig.11 As shown in (b), the control unit opens the third expansion valve 13, and the gas-liquid separator heat pump system 200 operates in series dehumidification and heating mode with the waste heat recovery function turned on. At this time, the fourth refrigerant flow path and the fifth refrigerant flow path are connected in parallel, and the liquid refrigerant flowing out of the gas-liquid separator 8 is divided into the fourth refrigerant flow path and the fifth refrigerant flow path. On the one hand, the refrigerant flowing into the fourth refrigerant flow path is throttled and expanded when passing through the second expansion valve 5 to become a low-temperature and low-pressure two-phase refrigerant, and then heat-exchanged with the air in the vehicle interior in the third heat exchanger 6 to dehumidify it. On the other hand, the refrigerant flowing into the fifth refrigerant flow path is throttled and expanded when passing through the third expansion valve 13 to become a low-temperature and low-pressure two-phase refrigerant, and then the refrigerant evaporates in the fourth heat exchanger 14 as a waste heat recovery device to absorb the waste heat of the vehicle-mounted heating components and become a low-pressure refrigerant close to the gas state. The above two refrigerants merge and return to the compressor 1.

[0107] According to the above structure, under the control of the control unit, the gas-liquid separator heat pump system 200 can operate in the series dehumidification and heating mode with the waste heat recovery function turned on or off, thereby selectively recovering waste heat according to the vehicle thermal management requirements while performing series dehumidification and heating in the vehicle. Figure 3 , Figure 4 The waste heat recovery control strategy is executed in that way, thereby ensuring that the heating efficiency of the heat pump air-conditioning system when the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off, and effectively preventing the reduction in valve life and fluctuations in the heat pump air-conditioning system caused by repeated opening and closing of valves. The waste heat recovery control strategy is the same as the waste heat recovery control strategy in the normal heating mode of the liquid storage tank heat pump system 100, so its description is omitted.

[0108] [Evaporator single dehumidification and heating mode]

[0109] Fig.12 Shows Figure 8 The refrigerant flow state of the heat pump air conditioning system shown in the figure when the evaporator is in the dehumidification and heating mode alone. (a) is the refrigerant flow state when the waste heat recovery function is turned off; (b) is the refrigerant flow state when the waste heat recovery function is turned on. Fig.12 As shown in (a) and (b), the control unit closes the first solenoid valve 12a to block the second refrigerant flow path, opens the second solenoid valve 12b to connect the third refrigerant flow path, closes the third solenoid valve 12c to block the sixth refrigerant flow path, and throttles the second expansion valve 5 to connect the fourth refrigerant flow path, thereby operating the evaporator single dehumidification and heating mode. In the evaporator single dehumidification and heating mode, the control unit turns on the waste heat recovery function by opening the third expansion valve 13, that is, by connecting the fifth refrigerant flow path, and turns off the waste heat recovery function by closing the third expansion valve 13, that is, by blocking the fifth refrigerant flow path.

[0110] Specifically, if Fig.12 As shown in (a), when the gas-liquid separator heat pump system 200 operates in the evaporator single dehumidification and heating mode with the third expansion valve 13 closed, that is, the waste heat recovery function is closed, the compressor 1, the first heat exchanger 2, the third refrigerant flow path and the fourth refrigerant flow path are connected in series in sequence, and the refrigerant circulates in the gas-liquid separator heat pump system 200 in the following form: the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 releases heat in the first heat exchanger 2 to become a medium-temperature and high-pressure liquid refrigerant, and flows into the gas-liquid separator 8 through the third refrigerant flow path; the liquid refrigerant flowing out of the gas-liquid separator 8 flows into the fourth refrigerant flow path, and is throttled and expanded when passing through the second expansion valve 5 to become a low-temperature and low-pressure two-phase refrigerant, and then exchanges heat with the interior air in the third heat exchanger 6 to dehumidify it, and then returns to the compressor 1 through the liquid storage tank 7.

[0111] When the system determines that waste heat recovery is required, such as Fig.12 As shown in (b), the control unit operates the series dehumidification and heating mode with the third expansion valve 13 open, that is, the waste heat recovery function is turned on. At this time, on the basis that the compressor 1, the first heat exchanger 2, the third refrigerant flow path and the fourth refrigerant flow path are connected in series in sequence, the fifth refrigerant flow path is connected in parallel with the fourth refrigerant flow path. After the refrigerant flows out of the gas-liquid separator 8, it is divided into the fourth refrigerant flow path and the fifth refrigerant flow path. On the one hand, the high-pressure refrigerant flowing into the fourth refrigerant flow path is throttled and expanded to become a low-temperature and low-pressure two-phase refrigerant when passing through the second expansion valve 5 as described above, and the air in the vehicle interior is dehumidified in the third heat exchanger 6. On the other hand, the refrigerant flowing into the fifth refrigerant flow path is throttled and expanded to become a low-temperature and low-pressure two-phase refrigerant when passing through the third expansion valve 13, and then absorbs the waste heat of the vehicle-mounted heating components in the fourth heat exchanger 14 as a waste heat recovery device to become a low-pressure refrigerant close to the gas state. The above two refrigerants merge and return to the compressor 1.

[0112] According to the above structure, under the control of the control unit, the gas-liquid separator heat pump system 200 can operate the evaporator dehumidification and heating mode with the waste heat recovery function turned on or off, thereby selectively recovering waste heat according to the vehicle thermal management requirements while performing evaporator dehumidification and heating in the vehicle. Figure 3 , Figure 4 The waste heat recovery control strategy is executed in that way, thereby ensuring that the heating efficiency of the heat pump air-conditioning system when the waste heat recovery function is turned on is always higher than the heating efficiency when the waste heat recovery function is turned off, and effectively preventing the reduction in valve life and fluctuations in the heat pump air-conditioning system caused by repeated opening and closing of valves. The waste heat recovery control strategy is the same as the waste heat recovery control strategy in the normal heating mode of the liquid storage tank heat pump system 100, so its description is omitted.

[0113] In addition, it should be noted that the above-mentioned liquid storage tank heat pump system 100 is not limited to Figure 1 As a variation of the liquid storage tank heat pump system 100, Fig.13 A tank heat pump system 100A is shown as a modified example of the tank heat pump system 100 .

[0114] like Fig.13As shown, unlike the liquid storage tank heat pump system 100, the liquid storage tank heat pump system 100A no longer has a first cooling water circuit. Instead, the first heat exchanger 22, which is a condenser in the vehicle interior (refrigerant-air heat exchanger), is directly used to release heat to the air. As an option, a PCT heater 23 can be set at the air outlet of the air conditioning system for auxiliary heating. In addition, the liquid storage tank heat pump system 100A no longer has a second cooling water circuit, but a fourth heat exchanger 24 of a refrigerant direct cooling style is set on the fifth refrigerant flow path to directly recover the waste heat of the battery and the strong electric system.

[0115] Likewise, the gas-liquid separator heat pump system 200 is not limited to Figure 8 The structure shown may also be a first cooling water circuit provided as in the liquid storage tank heat pump system 100 and a refrigerant-cooling water type heat exchanger may be used to replace the air-cooled first heat exchanger 2. A second cooling water circuit may also be provided as in the liquid storage tank heat pump system 100 and a refrigerant-cooling water type waste heat recovery device may be used to replace the fourth heat exchanger 14.

[0116] The above specific implementations further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above is only a specific implementation of the present invention and is not limited to the protection scope of the present invention. Without departing from the purpose of the basic characteristics of the present invention, the present invention can be embodied in various forms. Therefore, the implementation forms in the present invention are used for illustration rather than limitation. Since the scope of the present invention is limited by the claims rather than the specification, and all changes within the scope defined by the claims or within the equivalent scope of the scope defined by the claims should be understood to be included in the claims. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat pump air conditioning system, characterized in that: include: compressor; a first heat exchanger; A first refrigerant flow path having a first expansion valve and a second heat exchanger located downstream of the first expansion valve; A second refrigerant flow path provided with a first solenoid valve; A third refrigerant flow path provided with a second solenoid valve; A fourth refrigerant flow path having a second expansion valve and a third heat exchanger disposed downstream of the second expansion valve; A fifth refrigerant flow path having a third expansion valve and a fourth heat exchanger disposed downstream thereof; and Fluid storage tank; The heat pump air conditioning system is further provided with a control unit, and the heat pump air conditioning system controls at least one of the first to second expansion valves and the first to second solenoid valves through the control unit to switch different connection modes between the first refrigerant flow path and the fourth refrigerant flow path, thereby operating a plurality of different heating modes; When the heat pump air conditioning system operates the plurality of different heating modes, the control unit controls to turn on or off a waste heat recovery function that absorbs heat from a vehicle-mounted heating component through the fourth heat exchanger in the following manner: comparing a waste heat recovery characteristic value of the heat pump air conditioning system with a preset first threshold value and a second threshold value that is greater than the first threshold value, and turning on the waste heat recovery function only when the waste heat recovery characteristic value is greater than the second threshold value when the waste heat recovery function is in a turned-off state, and turning off the waste heat recovery function only when the waste heat recovery characteristic value is less than the first threshold value when the waste heat recovery function is in a turned-on state; The first threshold is a threshold that causes the heating efficiency of the heat pump air conditioning system to exceed the waste heat recovery characteristic value when the waste heat recovery function is turned on when the waste heat recovery function is not turned on. The second threshold is a threshold of a waste heat recovery characterization value that comprehensively considers the operating life of the third expansion valve and the heat loss of waste heat, so that the heating efficiency of the heat pump air-conditioning system is higher when the waste heat recovery function is turned on than when the waste heat recovery function is not turned on.

2. A heat pump air conditioning system, characterized in that: include: compressor; a first heat exchanger; A first refrigerant flow path having a first expansion valve and a second heat exchanger located downstream of the first expansion valve; A second refrigerant flow path provided with a first solenoid valve; A third refrigerant flow path provided with a second solenoid valve; A fourth refrigerant flow path having a second expansion valve and a third heat exchanger disposed downstream of the second expansion valve; A fifth refrigerant flow path provided with a third expansion valve and a fourth heat exchanger located downstream of the third expansion valve; Gas-liquid separator; A sixth refrigerant flow path provided with a third solenoid valve; a seventh refrigerant flow path connected to the liquid phase of the gas-liquid separator; and A refrigerant branch connected to the gas phase of the gas-liquid separator; The heat pump air conditioning system is further provided with a control unit, and the heat pump air conditioning system controls at least one of the first to second expansion valves and the first to third solenoid valves through the control unit to switch different connection modes between the refrigerant first flow path to the refrigerant fourth flow path and the refrigerant sixth flow path to the refrigerant seventh flow path, thereby operating a plurality of different heating modes; When the heat pump air conditioning system operates the plurality of different heating modes, the control unit controls to turn on or off a waste heat recovery function that absorbs heat from a vehicle-mounted heating component through the fourth heat exchanger in the following manner: comparing a waste heat recovery characteristic value of the heat pump air conditioning system with a preset first threshold value and a second threshold value that is greater than the first threshold value, and turning on the waste heat recovery function only when the waste heat recovery characteristic value is greater than the second threshold value when the waste heat recovery function is in a turned-off state, and turning off the waste heat recovery function only when the waste heat recovery characteristic value is less than the first threshold value when the waste heat recovery function is in a turned-on state; The first threshold is a threshold that causes the heating efficiency of the heat pump air conditioning system to exceed the waste heat recovery characteristic value when the waste heat recovery function is turned on when the waste heat recovery function is not turned on. The second threshold is a threshold of a waste heat recovery characterization value that comprehensively considers the operating life of the third expansion valve and the heat loss of waste heat, so that the heating efficiency of the heat pump air-conditioning system is higher when the waste heat recovery function is turned on than when the waste heat recovery function is not turned on.

3. The heat pump air conditioning system according to claim 1, characterized in that: The multiple different heating modes include a common heating mode. When the heat pump air conditioning system operates in the common heating mode, the compressor, the first heat exchanger, the first refrigerant flow path, and the second refrigerant flow path are connected in series, and the first expansion valve is throttled, the first solenoid valve is opened, and the second expansion valve is closed; The control unit controls the opening of the waste heat recovery function by opening the second solenoid valve and the third expansion valve to connect the third refrigerant flow path and the fifth refrigerant flow path, and controls the closing of the waste heat recovery function by closing at least one of the second solenoid valve and the third expansion valve to block the third refrigerant flow path or the fifth refrigerant flow path.

4. The heat pump air conditioning system according to claim 1, characterized in that: The multiple different heating modes include a parallel dehumidification heating mode. When the heat pump air conditioning system operates in the parallel dehumidification heating mode, the compressor, the first heat exchanger, the first refrigerant flow path, and the second refrigerant flow path are connected in series, and a flow path formed by the first refrigerant flow path and the second refrigerant flow path in series and a flow path formed by the third refrigerant flow path and the fourth refrigerant flow path in series are connected in parallel, and the first expansion valve and the second expansion valve are throttled, and the first solenoid valve and the second solenoid valve are opened; The control unit controls the opening or closing of the waste heat recovery function by opening or closing the third expansion valve to connect or block the fifth refrigerant flow path.

5. The heat pump air conditioning system according to claim 1, characterized in that: The multiple different heating modes include a series dehumidification heating mode. When the heat pump air conditioning system operates in the series dehumidification heating mode, the compressor, the first heat exchanger, the first refrigerant flow path, and the fourth refrigerant flow path are connected in series, and the first expansion valve and the second expansion valve are throttled, and the first solenoid valve and the second solenoid valve are closed; The control unit controls the opening or closing of the waste heat recovery function by opening or closing the third expansion valve to connect or block the fifth refrigerant flow path.

6. The heat pump air conditioning system according to claim 1, characterized in that: The multiple different heating modes include an evaporator-only dehumidification and heating mode. When the heat pump air-conditioning system operates in the evaporator-only dehumidification and heating mode, the compressor, the first heat exchanger, the third refrigerant flow path, and the fourth refrigerant flow path are connected in series, and the second solenoid valve is opened, the second expansion valve is throttled, and the first expansion valve and the first solenoid valve are closed; The control unit controls the opening or closing of the waste heat recovery function by opening or closing the third expansion valve to connect or block the fifth refrigerant flow path.

7. The heat pump air conditioning system according to claim 2, characterized in that: The multiple different heating modes include a common heating mode. When the heat pump air conditioning system operates in the common heating mode, the compressor, the first heat exchanger, the third refrigerant flow path, the seventh refrigerant flow path, the first refrigerant flow path, and the second refrigerant flow path are connected in series, and the first expansion valve is throttled, the first solenoid valve and the second solenoid valve are opened, and the third solenoid valve and the second expansion valve are closed; The control unit controls the opening or closing of the waste heat recovery function by opening or closing the third expansion valve to connect or block the fifth refrigerant flow path.

8. The heat pump air conditioning system according to claim 2, characterized in that: The multiple different heating modes include a parallel dehumidification heating mode. When the heat pump air conditioning system operates in the parallel dehumidification heating mode, the compressor, the first heat exchanger, the third refrigerant flow path, the seventh refrigerant flow path, the first refrigerant flow path, and the second refrigerant flow path are connected in series, and the flow path formed by the series connection of the first refrigerant flow path and the second refrigerant flow path and the fourth refrigerant flow path are connected in parallel, and the first expansion valve and the second expansion valve are throttled, the first solenoid valve and the second solenoid valve are opened, and the third solenoid valve is closed; The control unit controls the opening or closing of the waste heat recovery function by opening or closing the third expansion valve to connect or block the fifth refrigerant flow path.

9. The heat pump air conditioning system according to claim 2, characterized in that: The multiple different heating modes include a series dehumidification heating mode. When the heat pump air conditioning system operates in the series dehumidification heating mode, the compressor, the first heat exchanger, the sixth refrigerant flow path, the first refrigerant flow path, the refrigerant branch, and the fourth refrigerant flow path are connected in series, and the first expansion valve and the second expansion valve are throttled, the first solenoid valve and the second solenoid valve are closed, and the third solenoid valve is opened; The control unit controls the opening or closing of the waste heat recovery function by opening or closing the third expansion valve to connect or block the fifth refrigerant flow path.

10. The heat pump air conditioning system according to claim 2, characterized in that: The multiple different heating modes include an evaporator-only dehumidification and heating mode. When the heat pump air-conditioning system operates in the evaporator-only dehumidification and heating mode, the compressor, the first heat exchanger, the third refrigerant flow path, and the fourth refrigerant flow path are connected in series, and the second solenoid valve is opened, the second expansion valve is throttled, and the first expansion valve, the first solenoid valve, and the third solenoid valve are closed; The control unit controls the opening or closing of the waste heat recovery function by opening or closing the third expansion valve to connect or block the fifth refrigerant flow path.

11. The heat pump air conditioning system according to any one of claims 1 to 10, characterized in that: The waste heat recovery characterization value includes a heat load characterization value and a waste heat characterization value. The heat load characterization value is used to characterize the heat load of the heat pump air-conditioning system, and the waste heat characterization value is used to characterize the waste heat generated by the vehicle-mounted heating components.

12. The heat pump air conditioning system according to claim 11, characterized in that: When the waste heat recovery function of the heat pump air-conditioning system is in the off state, the control unit controls the waste heat recovery function to be switched from the off state to the on state only when the heat load characterization value is greater than the second threshold value of the heat load characterization value and the waste heat characterization value is greater than the second threshold value of the waste heat characterization value.

13. The heat pump air conditioning system according to claim 11, characterized in that: When the waste heat recovery function of the heat pump air-conditioning system is in the on state, the control unit controls the waste heat recovery function to be switched from the on state to the off state only when the heat load characterization value is less than the first threshold value of the heat load characterization value or the waste heat characterization value is less than the first threshold value of the waste heat characterization value.

14. The heat pump air conditioning system according to claim 11, characterized in that: The heat load characterization value is the rotation speed of the compressor or the power consumption of the compressor.

15. The heat pump air conditioning system according to claim 11, characterized in that: The waste heat characterization value is the difference between the cooling water temperature at any point between the cooling water inlet and the cooling water outlet of the fourth heat exchanger and the saturated refrigerant temperature flowing through the fourth heat exchanger. The saturated refrigerant temperature flowing through the fourth heat exchanger is calculated based on the pressure of the refrigerant outlet of the fourth heat exchanger or is calculated based on the smaller of the refrigerant inlet temperature and the refrigerant outlet temperature of the fourth heat exchanger.

16. The heat pump air conditioning system according to claim 11, characterized in that: The waste heat characterization value is the difference between the temperature of the vehicle-mounted heating component and the saturated refrigerant temperature flowing through the fourth heat exchanger. The saturated refrigerant temperature flowing through the fourth heat exchanger is calculated based on the pressure of the refrigerant outlet of the fourth heat exchanger or the smaller of the refrigerant inlet temperature and the refrigerant outlet temperature of the fourth heat exchanger.

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