Heat pump system and control method of heat pump system

Abstract

The invention relates to the technical field of heat pumps, and particularly discloses a heat pump system and a control method of the heat pump system.The system comprises a two-stage compressor, a four-way valve, an outdoor heat exchanger, an indoor heat exchanger, a heat exchanger, a first electronic expansion valve and a gas-liquid separator; a heat exchange main path and a first heat exchange branch path are formed in the heat pump system; due to the fact that the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve is adjusted based on the outdoor environment temperature and the air inlet temperature difference value between the inlet saturation temperature of the high-pressure cavity and the air suction port temperature, exhaust of the low-pressure cavity is cooled through the regenerative heat exchanger in the heat pump system; therefore, work of the two-stage compressor is reduced, and the exhaust temperature of the exhaust port of the two-stage compressor is effectively controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and in particular to a heat pump system and a control method for a heat pump system. Background Art

[0002] In the double-stage compressor of the existing heat pump system, the intermediate cooling form from the exhaust of the low-pressure chamber to the suction of the high-pressure chamber is cooled by supplementing low-temperature gas or liquid in the middle. This cooling method is affected by the amount of supplementary gas. If the intermediate supplementary gas is saturated or superheated gas, the amount of supplementary gas is small at this time, and the cooling effect is poor, resulting in a high temperature of the refrigerant entering the high-pressure chamber and a high exhaust temperature. If the intermediate supplementary gas is a two-phase refrigerant of gas and liquid, it is very difficult to control the amount of liquid refrigerant entering, and the vaporization of the liquid refrigerant is poor and the expansion has a negative effect on the system. The energy efficiency of the double-stage compression intermediate supplementary gas cooling scheme (intermediate incomplete cooling) compressor is low.

[0003] The above content is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The main object of the present invention is to provide a heat pump system and a control method for a heat pump system, aiming to solve the technical problems of high temperature of the intake air of the high-pressure chamber and low compression efficiency in the intermediate supplementary gas process from the exhaust of the low-pressure chamber to the intake of the high-pressure chamber in the double-stage compressor of the existing heat pump system.

[0005] To achieve the above object, the present invention provides a heat pump system, the heat pump system includes a double-stage compressor, a four-way valve, an outdoor heat exchanger, an indoor heat exchanger, a heat exchanger, a first electronic expansion valve and a gas-liquid separator. The double-stage compressor includes a low-pressure chamber and a high-pressure chamber. The heat pump system forms a main heat exchange path and a first heat exchange branch. The double-stage compressor, the four-way valve, the outdoor heat exchanger, the indoor heat exchanger, the four-way valve, the first electronic expansion valve and the gas-liquid separator are sequentially connected to form the main heat exchange path. The main heat exchange path includes a heat exchange pipe section connecting the exhaust port of the low-pressure chamber and the suction port of the high-pressure chamber. The heat exchanger is arranged in the first heat exchange branch and the heat exchange pipe section. The first heat exchange branch can exchange heat with the heat exchange pipe section through the heat exchanger. One end of the first heat exchange branch is connected between the four-way valve and the first electronic expansion valve, and the other end of the first heat exchange branch is connected between the first electronic expansion valve and the gas-liquid separator.

[0006] Optionally, the heat pump system further includes a subcooling heat exchanger and a second electronic expansion valve, and the heat pump system further forms a second heat exchange branch;

[0007] The subcooling heat exchanger is arranged in the main heat exchange path and the second heat exchange branch between the outdoor unit heat exchanger and the indoor heat exchanger. One end of the second heat exchange branch is connected to the main heat exchange path between the outdoor unit heat exchanger and the subcooling heat exchanger, and the other end of the second heat exchange branch is connected to the suction port of the high-pressure chamber. The second electronic expansion valve is arranged between the connection node between the second heat exchange branch and the main heat exchange path and the subcooling heat exchanger and is located in the second heat exchange branch.

[0008] Optionally, the heat pump system further includes a check valve. The check valve is arranged in the second heat exchange branch and is located between the subcooling heat exchanger and the suction port of the high-pressure chamber. The conducting direction of the check valve is from the subcooling heat exchanger to the suction port of the high-pressure chamber.

[0009] Optionally, the heat pump system further includes: a third electronic expansion valve and / or a fourth electronic expansion valve;

[0010] The third electronic expansion valve is arranged between the indoor heat exchanger and the subcooling heat exchanger and is located in the main heat exchange path; and / or

[0011] The fourth electronic expansion valve is arranged between the outdoor heat exchanger and the subcooling heat exchanger and is located in the main heat exchange path.

[0012] In addition, to achieve the above object, the present invention provides a control method for a heat pump system. The control method for the heat pump system is applied to the above heat pump system, and the method includes the following steps:

[0013] Obtain the inlet saturation temperature and the suction port temperature of the high-pressure chamber, and the outdoor ambient temperature;

[0014] Determine the intake air temperature difference according to the inlet saturation temperature and the suction port temperature; and

[0015] Adjust the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference.

[0016] Optionally, the obtaining the inlet saturation temperature and the suction port temperature of the high-pressure chamber includes:

[0017] Obtain the suction port pressure of the high-pressure chamber; and

[0018] Determine the inlet saturation temperature and the suction port temperature of the high-pressure chamber based on the suction port pressure.

[0019] Optionally, the adjusting the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference includes:

[0020] Obtain the current working mode;

[0021] When the working mode is the heating mode, determine whether the outdoor ambient temperature exceeds a first preset temperature;

[0022] If the outdoor ambient temperature exceeds the first preset temperature, set the default opening degree of the first electronic expansion valve to a first default opening degree;

[0023] Determine whether the intake air temperature difference exceeds a preset threshold, and adjust the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the difference determination result and the first default opening degree;

[0024] If the outdoor ambient temperature does not exceed the first preset temperature, set the default opening degree of the first electronic expansion valve to a second default opening degree; and

[0025] Determine whether the intake air temperature difference exceeds a preset threshold, and adjust the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the difference determination result and the second default opening degree.

[0026] Optionally, the determining whether the intake air temperature difference exceeds a preset threshold, and adjusting the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the difference determination result and the first default opening degree includes:

[0027] Determine whether the intake air temperature difference exceeds a preset threshold;

[0028] If the intake air temperature difference exceeds the preset threshold, adjust the opening degree of the first electronic expansion valve based on the first default opening degree, and adjust the opening degree of the second electronic expansion valve to a first target opening degree;

[0029] If the intake air temperature difference does not exceed the preset threshold, determine whether the intake air temperature difference is within a preset interval;

[0030] If the intake air temperature difference is within the preset interval, control the second electronic expansion valve to maintain the current opening degree; and

[0031] If the intake air temperature difference is not within the preset interval, adjust the opening degree of the first electronic expansion valve to a second target opening degree.

[0032] Optionally, the determining whether the intake air temperature difference exceeds a preset threshold, and adjusting the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the difference determination result and the second default opening degree includes:

[0033] Determine whether the intake air temperature difference exceeds a preset threshold;

[0034] If the intake air temperature difference exceeds the preset threshold, adjust the first electronic expansion valve to a third target opening based on the second default opening;

[0035] If the intake air temperature difference does not exceed the preset threshold, determine whether the intake air temperature difference is within a preset range;

[0036] If the intake air temperature difference is within the preset range, control the first electronic expansion valve to maintain the current opening; and

[0037] If the intake air temperature difference is not within the preset range, adjust the opening of the first electronic expansion valve to a fourth target opening based on the second default opening.

[0038] Optionally, after obtaining the current working mode, it further includes:

[0039] When the working mode is the refrigeration mode, determine whether the outdoor ambient temperature exceeds a second preset temperature;

[0040] If the outdoor ambient temperature does not exceed the second preset temperature, set the default opening of the second electronic expansion valve to a first default opening;

[0041] If the outdoor ambient temperature exceeds the second preset temperature, set the default opening of the second electronic expansion valve to a second default opening, and determine whether the intake air temperature difference exceeds the preset threshold; and

[0042] Adjust the opening of the first electronic expansion valve and the opening of the second electronic expansion valve based on the difference judgment result and the second default opening.

[0043] Optionally, the adjusting the opening of the first electronic expansion valve and the opening of the second electronic expansion valve based on the difference judgment result and the second default opening includes:

[0044] If the intake air temperature difference exceeds the preset threshold, determine whether the suction port temperature of the high-pressure chamber exceeds a third preset temperature, and adjust the opening of the second electronic expansion valve based on the temperature judgment result; and

[0045] If the intake air temperature difference does not exceed the preset threshold, determine whether the intake air temperature difference is within a preset range, and adjust the opening of the first electronic expansion valve and the opening of the second electronic expansion valve based on the range judgment result and the second default opening.

[0046] In addition, to achieve the above object, the present invention further provides a heat pump system, which includes a two-stage compressor, a heat exchanger, a first electronic expansion valve, and a second electronic expansion valve. The two-stage compressor includes a high-pressure chamber and a low-pressure chamber. The heat exchanger is respectively connected to the first electronic expansion valve, the second electronic expansion valve, the suction port of the two-stage compressor, the exhaust port of the low-pressure chamber, and the suction port of the high-pressure chamber. The first electronic expansion valve is respectively connected to the heat exchanger and the suction port of the two-stage compressor. The second electronic expansion valve is respectively connected to the heat exchanger and the suction port of the high-pressure chamber.

[0047] In addition, to achieve the above object, the present invention further provides a control device for a heat pump system, which includes:

[0048] A data acquisition module, configured to obtain the inlet saturation temperature and the suction port temperature of the high-pressure chamber, as well as the outdoor ambient temperature;

[0049] A difference calculation module, configured to determine the intake air temperature difference according to the inlet saturation temperature and the suction port temperature; and

[0050] An opening adjustment module, configured to adjust the opening of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference.

[0051] In addition, to achieve the above object, the present invention further provides a control device for a heat pump system, which includes: a memory, a processor, and a control program for the heat pump system stored on the memory and executable on the processor. The control program for the heat pump system is configured to implement the steps of the control method for the heat pump system as described above.

[0052] In addition, to achieve the above object, the present invention further provides a storage medium, on which a control program for a heat pump system is stored. When the control program for the heat pump system is executed by a processor, it implements the steps of the control method for the heat pump system as described above.

[0053] The present invention provides a heat pump system, which includes a two-stage compressor, a four-way valve, an outdoor heat exchanger, an indoor heat exchanger, a heat exchanger, a first electronic expansion valve, and a gas-liquid separator. The two-stage compressor includes a low-pressure chamber and a high-pressure chamber. The heat pump system forms a main heat exchange path and a first heat exchange branch. Since the present invention adjusts the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference, the exhaust gas of the low-pressure chamber is cooled by the regenerative heat exchanger in the heat pump system, the system return air temperature is increased, thereby reducing the work done by the two-stage compressor, improving the system energy efficiency, and effectively controlling the exhaust gas temperature at the exhaust port of the two-stage compressor, effectively improving the working efficiency and heat exchange reliability of the heat pump system. Description of the Drawings

[0054] Figure 1 It is a schematic structural diagram of a heat pump system in an embodiment of the present invention;

[0055] Figure 2 It is a schematic structural diagram of a control device of a heat pump system in the hardware operating environment related to the embodiment solution of the present invention;

[0056] Figure 3 It is a schematic flowchart of the first embodiment of the control method of the heat pump system of the present invention;

[0057] Figure 4 It is a schematic flowchart of the regenerative heat control process of the heat pump system in an embodiment of the present invention;

[0058] Figure 5 It is a P-h diagram of two-stage supplementary gas cooling compression in an embodiment of the present invention;

[0059] Figure 6 It is a schematic diagram of the refrigeration system principle of the heat pump system in an embodiment of the present invention;

[0060] Figure 7 It is a schematic flowchart of the refrigeration regenerative heat control process in an embodiment of the present invention;

[0061] Figure 8 It is a structural block diagram of the first embodiment of the control device of the heat pump system of the present invention.

[0062] Explanation of the reference numerals in the drawings:

[0063] Label Name Label Name 1 Regenerative heat exchanger 2 Suction port of two-stage compressor 3 Discharge port of low-pressure chamber 4 Suction port of high-pressure chamber 5 Discharge port of two-stage compressor 6 Oil separator 7 Four-way valve 8 Indoor heat exchanger 9 Fourth electronic expansion valve 10 Subcooling heat exchanger 11 Second electronic expansion valve 12 Third electronic expansion valve 13 Outdoor heat exchanger 14 First electronic expansion valve 15 Gas-liquid separator 16 Oil return capillary tube 17 Check valve T1 First-stage discharge temperature sensor T2 Second-stage discharge temperature sensor T3 Indoor heat exchanger temperature sensor T4 Outdoor heat exchanger temperature sensor P1 First-stage compression pressure sensor P2 Discharge pressure sensor P3 Suction pressure sensor A Two-stage compressor L Low-pressure chamber H High-pressure chamber

[0064] The realization, functional features, and advantages of the object of the present invention will be further described with reference to the embodiments and the drawings. Detailed Embodiments

[0065] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0066] An embodiment of the present invention provides a heat pump system. Refer to Figure 1 , Figure 1 As shown in the structural schematic diagram of the heat pump system, the heat pump system includes a two-stage compressor, a four-way valve 7, an outdoor heat exchanger 13, an indoor heat exchanger 8, a heat exchanger, a first electronic expansion valve 14, and a gas-liquid separator 15. The two-stage compressor includes a low-pressure chamber and a high-pressure chamber. The heat pump system forms a main heat exchange path and a first heat exchange branch. The two-stage compressor, the four-way valve 7, the outdoor heat exchanger 13, the indoor heat exchanger 8, the four-way valve 7, the first electronic expansion valve 14, and the gas-liquid separator 15 are sequentially connected to form the main heat exchange path. The main heat exchange path includes a heat exchange pipe section connecting the exhaust port 3 of the low-pressure chamber and the suction port 4 of the high-pressure chamber. The heat exchanger is disposed in the first heat exchange branch and the heat exchange pipe section. The first heat exchange branch can exchange heat with the heat exchange pipe section through the heat exchanger. One end of the first heat exchange branch is connected between the four-way valve 7 and the first electronic expansion valve 14, and the other end of the first heat exchange branch is connected between the first electronic expansion valve 14 and the gas-liquid separator 15.

[0067] Further, the heat pump system further includes a subcooling heat exchanger 10 and a second electronic expansion valve 11, and the heat pump system further forms a second heat exchange branch;

[0068] The subcooling heat exchanger 10 is disposed in the main heat exchange path and the second heat exchange branch between the outdoor heat exchanger and the indoor heat exchanger 8. One end of the second heat exchange branch is connected to the main heat exchange path between the outdoor heat exchanger and the subcooling heat exchanger 10, and the other end of the second heat exchange branch is connected to the suction port 4 of the high-pressure chamber. The second electronic expansion valve 11 is disposed between the connection node between the second heat exchange branch and the main heat exchange path and the subcooling heat exchanger 10 and is located in the second heat exchange branch.

[0069] Further, the heat pump system further includes a check valve 17. The check valve 17 is disposed in the second heat exchange branch and is located between the subcooling heat exchanger 10 and the suction port 4 of the high-pressure chamber. The conducting direction of the check valve 17 is from the subcooling heat exchanger 10 to the suction port 4 of the high-pressure chamber.

[0070] Further, the heat pump system further includes: a third electronic expansion valve 12 and / or a fourth electronic expansion valve 9;

[0071] The third electronic expansion valve 12 is disposed between the indoor heat exchanger 8 and the subcooling heat exchanger 10 and is located in the main heat exchange path; and / or

[0072] The fourth electronic expansion valve 9 is disposed between the outdoor heat exchanger 13 and the subcooling heat exchanger 10 and is located in the main heat exchange path.

[0073] It should be understood that during the heating process, the refrigerant flow is as Figure 1 shown by the solid arrows. After passing through the outdoor heat exchanger, the refrigerant has two ways to enter the liquid storage tank and return to the compressor at point a. The first electronic expansion valve 14 is default closed. The refrigerant enters the regenerative heat exchanger 1 from point a. The regenerative heat exchanger 1 cools the exhaust gas of the low-pressure chamber and raises the temperature of the suction gas.

[0074] It can be understood that as Figure 6 shown, the main components of the heat pump system include a two-stage compressor, a four-way valve 7, a regenerative heat exchanger 1, an indoor heat exchanger, an electronic expansion valve, an oil separator 6, a subcooling heat exchanger 10, an outdoor heat exchanger 13, a temperature sensor, a pressure sensor, a check valve 17, etc. During the refrigeration process, the refrigerant flow is as Figure 6 shown by the solid arrows. When the outdoor temperature is lower than b°C during refrigeration, the second electronic expansion valve 11 is default in the long-closed state, and the superheat degree c of the first-stage exhaust is controlled by adjusting the first electronic expansion valve 14.

[0075] In a specific implementation, the heat pump system may include a two-stage compressor, a regenerative heat exchanger 1, an oil separator 6, a four-way valve 7, an indoor heat exchanger 8, a first electronic expansion valve 14, a second electronic expansion valve 11, a third electronic expansion valve 12, a fourth electronic expansion valve 9, a subcooling heat exchanger 10, an outdoor heat exchanger 13, a gas-liquid separator 15, an oil return capillary 16, a check valve 17, a first-stage exhaust temperature sensor T1, a second-stage exhaust temperature sensor T2, an indoor heat exchanger temperature sensor T3, an outdoor heat exchanger temperature sensor T4, a first-stage compression pressure sensor P1, an exhaust pressure sensor P2, and a suction pressure sensor P3.

[0076] Referring to Figure 1 , the exhaust port of the low-pressure chamber of the two-stage compressor is connected to the regenerative heat exchanger 1. The compressor suction port 2 is respectively connected to the gas-liquid separator 15 and the oil return capillary 16. The suction port 4 of the high-pressure chamber of the two-stage compressor is respectively connected to the regenerative heat exchanger 1 and the subcooling heat exchanger 10. A check valve 17 is also connected between the subcooling heat exchanger 10 and the suction port 4. The compressor exhaust port 5 is connected to the oil separator 6. One end of the outdoor heat exchanger 13 is connected to the four-way valve 7, and the other end is connected to the third electronic expansion valve 12. The second electronic expansion valve 11 is respectively connected to the third electronic expansion valve 12 and the subcooling heat exchanger 10. One end of the indoor heat exchanger 8 is connected to the four-way valve 7, and the other end is connected to the fourth electronic expansion valve 9. The fourth electronic expansion valve 9 is respectively connected to the indoor heat exchanger and the subcooling heat exchanger 10. The gas-liquid separator 15 is respectively connected to the two-stage compressor, the first electronic expansion valve 14, and the regenerative heat exchanger 1.

[0077] This embodiment provides a heat pump system, which includes a two-stage compressor, a four-way valve, an outdoor heat exchanger, an indoor heat exchanger, a heat exchanger, a first electronic expansion valve, and a gas-liquid separator. The two-stage compressor includes a low-pressure chamber and a high-pressure chamber. The heat pump system forms a main heat exchange path and a first heat exchange branch. Since the present invention adjusts the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference, the exhaust gas of the low-pressure chamber is cooled by the regenerative heat exchanger in the heat pump system, the system suction gas temperature is increased, thereby reducing the work done by the two-stage compressor, improving the system energy efficiency, and effectively controlling the exhaust gas temperature at the exhaust port of the two-stage compressor, effectively improving the working efficiency and heat exchange reliability of the heat pump system.

[0078] Refer to Figure 2 , Figure 2 It is a schematic structural diagram of the control device of the heat pump system for the hardware operating environment involved in the solution of the embodiment of the present invention.

[0079] As Figure 2 shown, the control device of the heat pump system may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. Among them, the communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display) and an input unit such as a keyboard (Keyboard). Optionally, the user interface 1003 may further include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a wireless fidelity (Wi-Fi) interface). The memory 1005 may be a high-speed random access memory (Random Access Memory, RAM), or a stable non-volatile memory (Non-Volatile Memory, NVM), such as a disk memory. Optionally, the memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0080] Those skilled in the art can understand that Figure 2 the structure shown in

[0081] As Figure 2 shown, the memory 1005, as a storage medium, may include an operating system, a network communication module, a user interface module, and a control program for the heat pump system.

[0082] InFigure 2 In the control device of the heat pump system shown, the network interface 1004 is mainly used for data communication with a network server; the user interface 1003 is mainly used for data interaction with a user; the processor 1001 and the memory 1005 in the control device of the heat pump system of the present invention can be arranged in the control device of the heat pump system. The control device of the heat pump system calls the control program of the heat pump system stored in the memory 1005 through the processor 1001 and executes the control method of the heat pump system provided by the embodiments of the present invention.

[0083] In addition, embodiments of the present invention provide a control method for a heat pump system. Refer to Figure 3 , Figure 3 which is a schematic flowchart of the first embodiment of a control method for a heat pump system of the present invention.

[0084] In this embodiment, the control method for the heat pump system includes the following steps:

[0085] Step S10: Obtain the inlet saturation temperature and the suction port temperature of the high-pressure chamber, as well as the outdoor ambient temperature.

[0086] It should be understood that the execution subject of this embodiment is a controller, mainly a controller connected to the heat pump system, which can be a device capable of controlling the opening degree, adjustment, and switching of each component of the heat pump system, and can perform data processing and transmission, or can also be other devices capable of implementing this function. This embodiment does not limit this.

[0087] It should be noted that the control method for the heat pump system described in this embodiment is applied to a heat pump system. Refer to Figure 1 , Figure 1 which is a schematic structural diagram of the heat pump system. The heat pump system may include a two-stage compressor, a regenerative heat exchanger 1, an oil separator 6, a four-way valve 7, an indoor heat exchanger 8, a first electronic expansion valve 14, a second electronic expansion valve 11, a third electronic expansion valve 12, a fourth electronic expansion valve 9, a subcooling heat exchanger 10, an outdoor heat exchanger 13, a gas-liquid separator 15, an oil return capillary 16, a check valve 17, a first-stage exhaust temperature sensor T1, a second-stage exhaust temperature sensor T2, an indoor heat exchanger temperature sensor T3, an outdoor heat exchanger temperature sensor T4, a first-stage compression pressure sensor P1, an exhaust pressure sensor P2, and a suction pressure sensor P3.

[0088] Refer to Figure 1, the exhaust port of the low-pressure chamber of the two-stage compressor is connected to the regenerative heat exchanger 1, and the suction port 2 of the compressor is respectively connected to the gas-liquid separator 15 and the oil return capillary 16; the suction port 4 of the high-pressure chamber of the two-stage compressor is respectively connected to the regenerative heat exchanger 1 and the subcooling heat exchanger 10; a check valve 17 is also connected between the subcooling heat exchanger 10 and the suction port 4; the compressor exhaust port 5 is connected to the oil separator 6; one end of the outdoor heat exchanger 13 is connected to the four-way valve 7, and the other end is connected to the third electronic expansion valve 12; the second electronic expansion valve 11 is respectively connected to the third electronic expansion valve 12 and the subcooling heat exchanger 10; one end of the indoor heat exchanger 8 is connected to the four-way valve 7, and the other end is connected to the fourth electronic expansion valve 9; the fourth electronic expansion valve 9 is respectively connected to the indoor heat exchanger and the subcooling heat exchanger 10; the gas-liquid separator 15 is respectively connected to the two-stage compressor, the first electronic expansion valve 14 and the regenerative heat exchanger 1.

[0089] Further, in order to accurately obtain the inlet saturation temperature of the high-pressure chamber H, the above step S10 may include:

[0090] Obtaining the suction port pressure of the high-pressure chamber; and

[0091] Based on the suction port pressure, determining the inlet saturation temperature and the suction port temperature of the high-pressure chamber.

[0092] It should be noted that measuring the suction port temperature and the suction port pressure of the high-pressure chamber is to measure the temperature and pressure at the point in the figure, and then calculate the suction port saturation temperature of the high-pressure chamber according to the suction port pressure. The suction port saturation temperature is calculated by a preset program, and specifically, it can be calculated with reference to the pressure-enthalpy diagram. When the suction port pressure is determined, the only determined value can be obtained as the suction port saturation temperature.

[0093] Step S20: Determine the intake air temperature difference according to the inlet saturation temperature and the suction port temperature.

[0094] It should be understood that after calculating the saturation temperature of the suction port 4, the intake air temperature difference is determined by taking the difference, and then the opening degree of the electronic expansion valve is adjusted according to the intake air temperature difference. Thus, the refrigerant flow rate flowing to the heat exchanger can be changed by the change of the opening degree of the electronic expansion valve, so that indirect heat exchange can be carried out between the system return air and the primary compression exhaust. At the same time, the heat exchanger has a certain storage capacity for the primary compression exhaust, preventing liquid refrigerant from entering the secondary suction. The above primary compression exhaust can be the exhaust of the low-pressure chamber, and the above secondary suction can be the intake of the high-pressure chamber.

[0095] Step S30: Adjust the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference.

[0096] It can be understood that referring toFigure 1 The controller of the heat pump system detects the intake pressure of the high-pressure chamber H through the first-stage compression pressure sensor P1, converts the pressure detected by the first-stage compression pressure sensor P1 into the corresponding inlet saturation temperature, and simultaneously calculates the difference between the intake port 4 temperature collected by the first-stage exhaust temperature sensing package T1 and the inlet saturation temperature to obtain the intake temperature difference, and adjusts the opening of the first electronic expansion valve 14 and the second electronic expansion valve 11 according to the intake temperature difference and the outdoor ambient temperature, thereby improving the heat exchange efficiency and reliability of the two-stage compression system.

[0097] It is understandable that, referring to Figure 1 When the heat pump system is heating, the inlet pressure of the high-pressure chamber is detected by P1, and the pressure detected by P1 is converted into the corresponding temperature A1 through the control program. At the same time, the difference between T1 and A1 is calculated through the control program. The control logic is as follows: Figure 4 As shown, Figure 4 It is a schematic diagram of the heat recovery control process of the heat pump system. By detecting T1 and P1, the saturation temperature A1 corresponding to P1 is calculated through the program. By determining the difference between T1-A1, the opening of the second electronic expansion valve and the first electronic expansion valve is controlled, thereby improving the workmanship energy efficiency and heat exchange reliability of the two-stage compression system.

[0098] It should be understood that referring to Figure 5 , Figure 5 It is a two-stage air supply cooling compression Ph diagram. The first-stage exhaust gas compressed by the low-pressure chamber L is cooled by the heat exchanger. The intake temperature of the high-pressure chamber is close to saturation (point d or point e). The role of the heat exchanger is to reduce the first-stage exhaust temperature and increase the system return air temperature, thereby reducing the work done by the compressor, improving the system heat exchange efficiency, and effectively controlling the exhaust temperature at the compressor exhaust port.

[0099] Furthermore, in order to accurately control the opening of the electronic expansion valve, the above step S30 may include:

[0100] Get the current working mode;

[0101] When the working mode is the heating mode, determining whether the outdoor ambient temperature exceeds a first preset temperature;

[0102] If the outdoor ambient temperature exceeds the first preset temperature, setting the default opening of the first electronic expansion valve to a first default opening;

[0103] Determining whether the intake air temperature difference exceeds a preset threshold, and adjusting the opening of the first electronic expansion valve and the opening of the second electronic expansion valve based on the difference determination result and the first default opening;

[0104] If the outdoor ambient temperature does not exceed the first preset temperature, set the default opening degree of the first electronic expansion valve to the second default opening degree; and

[0105] Judge whether the intake air temperature difference exceeds a preset threshold, and adjust the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve based on the difference judgment result and the second default opening degree.

[0106] It should be noted that the current working mode can be the working mode of the heat pump system. For example, the current working mode can include a refrigeration working mode and a heating working mode.

[0107] It should be understood that with reference to Figure 5 , Figure 5 is a schematic diagram of the heat recovery control process of the heat pump system. When the controller receives a heating start command, it turns on the heating mode and judges whether the outdoor ambient temperature is greater than a degrees Celsius; if the outdoor ambient temperature is greater than the first preset temperature, set the default opening degree of the first electronic expansion valve 14 to 0 opening degree; judge whether T1 - A1 is greater than c (that is, whether the intake air temperature difference is greater than c); if the intake air temperature difference is greater than c, adjust the opening degree of the first electronic expansion valve 14 based on the first default opening degree, and adjust the opening degree of the second electronic expansion valve 11 to m opening degree; if the intake air temperature difference is not greater than c, then judge c > T1 - A1 > 0; if the intake air temperature difference is within the preset interval, control the second electronic expansion valve 11 to maintain the current opening degree; if the intake air temperature difference is not within the preset interval, adjust the opening degree of the first electronic expansion valve to F opening degree.

[0108] If the outdoor ambient temperature is not greater than the first preset temperature, set the default opening degree of the first electronic expansion valve 14 to F opening degree; judge whether the intake air temperature difference is greater than c. If the intake air temperature difference is greater than c, adjust the first electronic expansion valve 14 to F - n opening degree based on the second default opening degree; if the intake air temperature difference is not greater than c, then judge whether the intake air temperature difference is within the preset interval; if the intake air temperature difference is within the preset interval, control the first electronic expansion valve 14 to maintain the current opening degree; if the intake air temperature difference is not within the preset interval, adjust the opening degree of the first electronic expansion valve to F + n opening degree based on the second default opening degree.

[0109] Furthermore, in order to accurately adjust the opening degree of the electronic expansion valve in the refrigeration mode to improve the refrigeration efficiency, after obtaining the current working mode, it further includes:

[0110] When the working mode is the refrigeration mode, judge whether the outdoor ambient temperature exceeds the second preset temperature;

[0111] If the outdoor ambient temperature does not exceed the second preset temperature, set the default opening degree of the second electronic expansion valve to the first default opening degree;

[0112] If the outdoor ambient temperature exceeds the second preset temperature, set the default opening degree of the second electronic expansion valve to the second default opening degree, and determine whether the intake air temperature difference exceeds the preset threshold; and

[0113] Adjust the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the difference judgment result and the second default opening degree.

[0114] It should be noted that referring to Figure 6 and Figure 7 , Figure 6 is the schematic diagram of the refrigeration system of the heat pump system, Figure 7 is the schematic diagram of the refrigeration heat recovery control process. As Figure 6 shown, the main components of the heat pump system include a two-stage compressor, a four-way valve 7, a heat recovery heat exchanger, an indoor heat exchanger 8, an electronic expansion valve, an oil separator 6, a subcooling heat exchanger, an outdoor heat exchanger, a temperature sensor, a pressure sensor, a check valve 17, etc. The refrigerant flow during the refrigeration process is as Figure 6 shown by the solid arrows. When the outdoor temperature is lower than b °C during refrigeration, the second electronic expansion valve 11 is default in the long-closed state, and the superheat degree c of the first-stage exhaust is controlled by adjusting the first electronic expansion valve 14.

[0115] It should be understood that as Figure 7 shown, when the controller receives a cold start instruction, it turns on the refrigeration mode, determines whether the outdoor ambient temperature is greater than b degrees Celsius (i.e., the second preset temperature). If it is not greater than b degrees Celsius, set the default opening degree of the second electronic expansion valve 11 to 0 opening degree. If the outdoor ambient temperature is greater than b degrees Celsius, set the default opening degree of the second electronic expansion valve 11 to the F opening degree, and determine whether the intake air temperature difference is greater than c. If the intake air temperature difference is greater than c, determine whether the temperature of the suction port 4 of the high-pressure chamber H is greater than t degrees Celsius. If it is greater than t degrees Celsius, adjust the opening degree of the second electronic expansion valve 11 to 2m opening degree, and continue to monitor whether the temperature of the suction port 4 of the high-pressure chamber H is greater than t degrees Celsius. If so, start the frequency reduction protection. If it is not greater than t degrees Celsius, keep the current opening degree of the second electronic expansion valve 11.

[0116] If the intake air temperature difference is not greater than c, determine whether the intake air temperature difference is within a preset range (i.e., c>T1 - A1>0). If it is within the preset range, adjust the opening degree of the second electronic expansion valve 11 from the F opening degree to 0 opening degree. If it is not within the preset range, adjust the opening degree of the second electronic expansion valve 11 to 0 opening degree, and adjust the default opening degree of the first electronic expansion valve 14 to the m opening degree.

[0117] Since this embodiment provides a heat pump system, the system includes a two-stage compressor, a four-way valve, an outdoor heat exchanger, an indoor heat exchanger, a heat exchanger, a first electronic expansion valve, and a gas-liquid separator. The two-stage compressor includes a low-pressure chamber and a high-pressure chamber. The heat pump system forms a main heat exchange path and a first heat exchange branch. Since the present invention adjusts the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference, the exhaust gas of the low-pressure chamber is cooled by the regenerative heat exchanger in the heat pump system, the system suction gas temperature is increased, thereby reducing the work done by the two-stage compressor, improving the system energy efficiency, and effectively controlling the exhaust gas temperature at the exhaust port of the two-stage compressor, effectively improving the working efficiency and heat exchange reliability of the heat pump system.

[0118] In addition, an embodiment of the present invention further provides a storage medium, on which a control program of the heat pump system is stored. When the control program of the heat pump system is executed by a processor, the steps of the control method of the heat pump system as described above are implemented.

[0119] Since this storage medium adopts all the technical solutions of the above all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one.

[0120] Refer to Figure 8 , Figure 8 which is the structural block diagram of the first embodiment of the control device of the heat pump system of the present invention.

[0121] As Figure 8 shown, the control device of the heat pump system proposed by the embodiment of the present invention includes:

[0122] A data acquisition module 10, configured to acquire the inlet saturation temperature and the suction port temperature of the high-pressure chamber, and the outdoor ambient temperature;

[0123] A difference calculation module 20, configured to determine an intake air temperature difference according to the inlet saturation temperature and the suction port temperature;

[0124] An opening degree adjustment module 30, configured to adjust the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference.

[0125] It should be noted that the heat pump system may include a two-stage compressor, a regenerative heat exchanger 1, an oil separator 6, a four-way valve 7, an indoor heat exchanger 8, a first electronic expansion valve 14, a second electronic expansion valve 11, a third electronic expansion valve 12, a fourth electronic expansion valve 9, a subcooling heat exchanger 10, an outdoor heat exchanger 13, a gas-liquid separator 15, an oil return capillary 16, a check valve 17, a first-stage discharge temperature sensor T1, a second-stage discharge temperature sensor T2, an indoor heat exchanger temperature sensor T3, an outdoor heat exchanger temperature sensor T4, a first-stage compression pressure sensor P1, a discharge pressure sensor P2, and a suction pressure sensor P3.

[0126] Referring to Figure 1 , the exhaust port of the low-pressure chamber of the two-stage compressor is connected to the regenerative heat exchanger 1, and the compressor suction ports 2 are respectively connected to the gas-liquid separator 15 and the oil return capillary 16; the suction port 4 of the high-pressure chamber of the two-stage compressor is respectively connected to the regenerative heat exchanger 1 and the subcooling heat exchanger 10; a check valve 17 is also connected between the subcooling heat exchanger 10 and the suction port 4; the compressor discharge port 5 is connected to the oil separator 6; one end of the outdoor heat exchanger 13 is connected to the four-way valve 7, and the other end is connected to the third electronic expansion valve 12; the second electronic expansion valve 11 is respectively connected to the third electronic expansion valve 12 and the subcooling heat exchanger 10; one end of the indoor heat exchanger 8 is connected to the four-way valve 7, and the other end is connected to the fourth electronic expansion valve 9; the fourth electronic expansion valve 9 is respectively connected to the indoor heat exchanger and the subcooling heat exchanger 10; the gas-liquid separator 15 is respectively connected to the two-stage compressor, the first electronic expansion valve 14, and the regenerative heat exchanger 1.

[0127] It can be understood that measuring the suction port temperature and suction port pressure of the high-pressure chamber is to measure the temperature and pressure at the point in the figure, and then calculate the suction port saturation temperature of the high-pressure chamber according to the suction port pressure. The suction port saturation temperature is calculated through a preset program, and specifically, it can be calculated with reference to the pressure-enthalpy diagram. When the suction port pressure is determined, the only determined value is the suction port saturation temperature.

[0128] It should be understood that after calculating the suction port 4 saturation temperature, the intake air temperature difference is determined by taking the difference, and then the opening degree of the electronic expansion valve is adjusted according to the intake air temperature difference. Thus, the refrigerant flow rate flowing to the heat exchanger can be changed by the change of the opening degree of the electronic expansion valve, so that indirect heat exchange can be carried out between the system suction and the first-stage compression discharge. At the same time, the heat exchanger has a certain storage capacity for the first-stage compression discharge to prevent liquid refrigerant from entering the second-stage suction. The above first-stage compression discharge can be the low-pressure chamber exhaust, and the above second-stage suction can be the high-pressure chamber intake.

[0129] It can be understood that referring to Figure 1The controller of the heat pump system detects the intake pressure of the high-pressure chamber H through the first-stage compression pressure sensor P1, converts the pressure detected by the first-stage compression pressure sensor P1 into the corresponding inlet saturation temperature, and simultaneously calculates the difference between the intake port 4 temperature collected by the first-stage exhaust temperature sensing package T1 and the inlet saturation temperature to obtain the intake temperature difference, and adjusts the opening of the first electronic expansion valve 14 and the second electronic expansion valve 11 according to the intake temperature difference and the outdoor ambient temperature, thereby improving the heat exchange efficiency and reliability of the two-stage compression system.

[0130] It should be noted that, refer to Figure 1 The main components of the heat pump system include a two-stage compressor, a four-way valve, a heat recovery heat exchanger, an indoor heat exchanger, an electronic expansion valve, an oil separator, a subcooling heat exchanger, an outdoor heat exchanger, a temperature sensor, a pressure sensor, a check valve, etc. The refrigerant flow in the heating process is as follows Figure 1 As shown by the solid arrows, after the refrigerant passes through the outdoor heat exchanger, there are two ways to enter the liquid storage tank and return to the compressor at point a. The first electronic expansion valve is closed by default, and the refrigerant enters the regenerative heat exchanger from point a. The regenerative heat exchanger cools the exhaust gas of the low-pressure chamber and raises the temperature of the return air.

[0131] It is understandable that, referring to Figure 1 When the heat pump system is heating, the inlet pressure of the high-pressure chamber is detected by P1, and the pressure detected by P1 is converted into the corresponding temperature A1 through the control program. At the same time, the difference between T1 and A1 is calculated through the control program. The control logic is as follows: Figure 4 As shown, Figure 4 It is a schematic diagram of the heat recovery control process of the heat pump system. By detecting T1 and P1, the saturation temperature A1 corresponding to P1 is calculated through the program. By determining the difference between T1-A1, the opening of the second electronic expansion valve and the first electronic expansion valve is controlled, thereby improving the workmanship energy efficiency and heat exchange reliability of the two-stage compression system.

[0132] It should be understood that referring to Figure 5 , Figure 5 It is a two-stage air supply cooling compression Ph diagram. The first-stage exhaust gas compressed by the low-pressure chamber L is cooled by the heat exchanger. The intake temperature of the high-pressure chamber is close to saturation (point d or point e). The role of the heat exchanger is to reduce the first-stage exhaust temperature and increase the system return air temperature, thereby reducing the work done by the compressor, improving the system heat exchange efficiency, and effectively controlling the exhaust temperature at the compressor exhaust port.

[0133] It should be understood that referring to Figure 5 , Figure 5It is a schematic diagram of the heat recovery control process for a heat pump system. When the controller receives a heating start command, it turns on the heating mode and determines whether the outdoor ambient temperature is greater than a degrees Celsius (i.e., the first preset temperature). If the outdoor ambient temperature is greater than a degrees Celsius, the default opening of the first electronic expansion valve 14 is set to the 0 opening. It is judged whether T1 - A1 is greater than c. If the intake air temperature difference is greater than c, the opening of the first electronic expansion valve 14 is adjusted based on the first default opening, and the opening of the second electronic expansion valve 11 is adjusted to the m opening. If the intake air temperature difference is not greater than c, it is judged that c > T1 - A1 > 0. If the intake air temperature difference is within the preset range, the second electronic expansion valve 11 is controlled to maintain the current opening. If the intake air temperature difference is not within the preset range, the opening of the first electronic expansion valve is adjusted to the F opening.

[0134] If the outdoor ambient temperature is not greater than a degrees Celsius, the default opening of the first electronic expansion valve 14 is set to the F opening. It is judged whether the intake air temperature difference is greater than c. If the intake air temperature difference is greater than c, the first electronic expansion valve 14 is adjusted to the F - n opening based on the second default opening. If the intake air temperature difference is not greater than c, it is judged whether the intake air temperature difference is within the preset range. If the intake air temperature difference is within the preset range, the first electronic expansion valve 14 is controlled to maintain the current opening. If the intake air temperature difference is not within the preset range, the opening of the first electronic expansion valve is adjusted to the F + n opening based on the second default opening.

[0135] It should be noted that referring to Figure 6 and Figure 7 , Figure 6 is the schematic diagram of the refrigeration system of the heat pump system, Figure 7 is the schematic diagram of the refrigeration heat recovery control process. As Figure 6 shown, the main components of the heat pump system include a two-stage compressor, a four-way valve 7, a heat recovery heat exchanger, an indoor heat exchanger 8, an electronic expansion valve, an oil separator 6, a subcooling heat exchanger, an outdoor heat exchanger, a temperature sensor, a pressure sensor, a check valve 17, etc. The refrigerant flow during the refrigeration process is as Figure 6 shown by the solid arrows. When the outdoor temperature is lower than b °C during refrigeration, the second electronic expansion valve 11 is default in the long-closed state, and the superheat degree c of the first-stage exhaust is controlled by adjusting the first electronic expansion valve 14.

[0136] It should be understood that as Figure 7As shown, when the controller receives a cold start instruction, it turns on the refrigeration mode and determines whether the outdoor ambient temperature is greater than b degrees Celsius (i.e., the second preset temperature). If it is not greater than b degrees Celsius, the default opening of the second electronic expansion valve 11 is set to the 0 opening. If the outdoor ambient temperature is greater than b degrees Celsius, the default opening of the second electronic expansion valve 11 is set to the F opening, and it is determined whether the intake air temperature difference is greater than c. If the intake air temperature difference is greater than c, it is determined whether the temperature of the suction port 4 of the high-pressure chamber H is greater than t degrees Celsius. If it is greater than t degrees Celsius, the opening of the second electronic expansion valve 11 is adjusted to the 2m opening, and the temperature of the suction port 4 of the high-pressure chamber H is continuously monitored to see if it is greater than t degrees Celsius. If so, the frequency reduction protection is started. If it is not greater than t degrees Celsius, the second electronic expansion valve 11 is maintained at the current opening.

[0137] If the intake air temperature difference is not greater than c, it is determined whether the intake air temperature difference is within a preset range (i.e., c>T1 - A1>0). If it is within the preset range, the opening of the second electronic expansion valve 11 is adjusted from the F opening to the 0 opening. If it is not within the preset range, the opening of the second electronic expansion valve 11 is adjusted to the 0 opening, and the default opening of the first electronic expansion valve 14 is adjusted to the m opening.

[0138] Since this embodiment adjusts the opening of the first electronic expansion valve and the second electronic expansion valve based on the outdoor ambient temperature and the intake air temperature difference between the inlet saturation temperature and the suction port temperature of the high-pressure chamber, the exhaust gas of the low-pressure chamber is cooled by the regenerative heat exchanger in the heat pump system, the system return air temperature is increased, thereby reducing the work done by the two-stage compressor, improving the system energy efficiency, and effectively controlling the exhaust gas temperature at the exhaust port of the two-stage compressor, effectively improving the work efficiency and heat exchange reliability of the heat pump system.

[0139] It should be understood that the above is only for illustration and does not constitute any limitation to the technical solution of the present invention. In specific applications, those skilled in the art can set according to needs, and the present invention does not limit this.

[0140] It should be noted that the above-described work process is only illustrative and does not limit the protection scope of the present invention. In actual applications, those skilled in the art can select some or all of them according to actual needs to achieve the purpose of the solution of this embodiment, and there is no limitation here.

[0141] In addition, for the technical details not described in detail in this embodiment, reference can be made to the control method of the heat pump system provided in any embodiment of the present invention, which will not be elaborated here.

[0142] In addition, it should be noted that in this text, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, method, article or system comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or system. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or system comprising that element.

[0143] The serial numbers of the above embodiments of the present invention are only for description and do not represent the superiority or inferiority of the embodiments.

[0144] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-described embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as Read Only Memory (ROM) / RAM, magnetic disk, optical disk), and includes several instructions for causing a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0145] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the description of the present invention and the accompanying drawings, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A heat pump system, characterized in that, The heat pump system includes a two-stage compressor, a four-way valve, an outdoor heat exchanger, an indoor heat exchanger, a heat exchanger, a first electronic expansion valve, and a gas-liquid separator. The two-stage compressor includes a low-pressure chamber and a high-pressure chamber. The heat pump system forms a main heat exchange path and a first heat exchange branch path. The two-stage compressor, the four-way valve, the outdoor heat exchanger, the indoor heat exchanger, the four-way valve, the first electronic expansion valve, and the gas-liquid separator are sequentially connected to form the main heat exchange path. The main heat exchange path includes a heat exchange pipe section connecting the exhaust port of the low-pressure chamber and the suction port of the high-pressure chamber. The heat exchanger is arranged in the first heat exchange branch path and the heat exchange pipe section. The first heat exchange branch path can exchange heat with the heat exchange pipe section through the heat exchanger. One end of the first heat exchange branch path is connected between the four-way valve and the first electronic expansion valve, and the other end of the first heat exchange branch path is connected between the first electronic expansion valve and the gas-liquid separator.

2. The heat pump system according to claim 1, characterized in that, The heat pump system further includes a subcooling heat exchanger and a second electronic expansion valve. The heat pump system further forms a second heat exchange branch path. The subcooling heat exchanger is arranged in the main heat exchange path and the second heat exchange branch path between the outdoor heat exchanger and the indoor heat exchanger. One end of the second heat exchange branch path is connected to the main heat exchange path between the outdoor heat exchanger and the subcooling heat exchanger. The other end of the second heat exchange branch path is connected to the suction port of the high-pressure chamber. The second electronic expansion valve is arranged between the connection node between the second heat exchange branch path and the main heat exchange path and the subcooling heat exchanger and is located in the second heat exchange branch path.

3. The heat pump system according to claim 2, characterized in that, The heat pump system further includes a check valve. The check valve is arranged in the second heat exchange branch path and is located between the subcooling heat exchanger and the suction port of the high-pressure chamber. The conducting direction of the check valve is from the subcooling heat exchanger to the suction port of the high-pressure chamber.

4. The heat pump system according to claim 2, characterized in that, The heat pump system further includes: a third electronic expansion valve and / or a fourth electronic expansion valve; The third electronic expansion valve is arranged between the indoor heat exchanger and the subcooling heat exchanger and is located in the main heat exchange path; and / or The fourth electronic expansion valve is arranged between the outdoor heat exchanger and the subcooling heat exchanger and is located in the main heat exchange path.

5. A control method for a heat pump system, characterized in that, The heat pump system includes a two-stage compressor, a four-way valve, an outdoor heat exchanger, an indoor heat exchanger, a heat exchanger, a first electronic expansion valve, and a gas-liquid separator. The two-stage compressor includes a low-pressure chamber and a high-pressure chamber. The heat pump system forms a main heat exchange path and a first heat exchange branch. The two-stage compressor, the four-way valve, the outdoor heat exchanger, the indoor heat exchanger, the four-way valve, the first electronic expansion valve, and the gas-liquid separator are sequentially connected to form the main heat exchange path. The main heat exchange path includes a heat exchange pipe section connecting the exhaust port of the low-pressure chamber and the suction port of the high-pressure chamber. The heat exchanger is arranged in the first heat exchange branch and the heat exchange pipe section. The first heat exchange branch can exchange heat with the heat exchange pipe section through the heat exchanger. One end of the first heat exchange branch is connected between the four-way valve and the first electronic expansion valve, and the other end of the first heat exchange branch is connected between the first electronic expansion valve and the gas-liquid separator; The control method of the heat pump system includes: Obtaining the inlet saturation temperature and the suction port temperature of the high-pressure chamber, and the outdoor ambient temperature; Determining the intake air temperature difference according to the inlet saturation temperature and the suction port temperature; and Adjusting the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference.

6. The control method for a heat pump system according to claim 5, characterized in that, The obtaining the inlet saturation temperature and the suction port temperature of the high-pressure chamber includes: Obtaining the suction port pressure of the high-pressure chamber; and Determining the inlet saturation temperature and the suction port temperature of the high-pressure chamber based on the suction port pressure.

7. The control method for a heat pump system according to claim 5, characterized in that, The adjusting the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference includes: Obtaining the current working mode; When the working mode is the heating mode, judging whether the outdoor ambient temperature exceeds a first preset temperature; If the outdoor ambient temperature exceeds the first preset temperature, setting the default opening degree of the first electronic expansion valve to a first default opening degree; Judging whether the intake air temperature difference exceeds a preset threshold, and adjusting the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve based on the difference judgment result and the first default opening degree; If the outdoor ambient temperature does not exceed the first preset temperature, setting the default opening degree of the first electronic expansion valve to a second default opening degree; and Judging whether the intake air temperature difference exceeds a preset threshold, and adjusting the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve based on the difference judgment result and the second default opening degree.

8. The control method for a heat pump system according to claim 7, characterized in that, The judging whether the intake air temperature difference exceeds a preset threshold, and adjusting the opening degree of the first electronic expansion valve and the opening degree of the second electronic expansion valve based on the difference judgment result and the first default opening degree includes: Judging whether the intake air temperature difference exceeds a preset threshold; If the intake air temperature difference exceeds the preset threshold, adjusting the opening degree of the first electronic expansion valve based on the first default opening degree, and adjusting the opening degree of the second electronic expansion valve to a first target opening degree; If the intake air temperature difference does not exceed the preset threshold, determine whether the intake air temperature difference is within a preset range; If the intake air temperature difference is within the preset range, control the second electronic expansion valve to maintain the current opening degree; and If the intake air temperature difference is not within the preset range, adjust the opening degree of the first electronic expansion valve to a second target opening degree.

9. The control method for a heat pump system according to claim 7, characterized in that, The judging whether the intake air temperature difference exceeds a preset threshold and adjusting the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the difference judgment result and the second default opening degree includes: Judge whether the intake air temperature difference exceeds a preset threshold; If the intake air temperature difference exceeds the preset threshold, adjust the first electronic expansion valve to a third target opening degree based on the second default opening degree; If the intake air temperature difference does not exceed the preset threshold, determine whether the intake air temperature difference is within a preset range; If the intake air temperature difference is within the preset range, control the first electronic expansion valve to maintain the current opening degree; and If the intake air temperature difference is not within the preset range, adjust the opening degree of the first electronic expansion valve to a fourth target opening degree based on the second default opening degree.

10. The control method of the heat pump system according to claim 6, characterized in that, After obtaining the current working mode, it further includes: When the working mode is the refrigeration mode, judge whether the outdoor ambient temperature exceeds a second preset temperature; If the outdoor ambient temperature does not exceed the second preset temperature, set the default opening degree of the second electronic expansion valve to a first default opening degree; If the outdoor ambient temperature exceeds the second preset temperature, set the default opening degree of the second electronic expansion valve to a second default opening degree, and judge whether the intake air temperature difference exceeds the preset threshold; and Adjust the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the difference judgment result and the second default opening degree.

11. The control method of the heat pump system according to claim 10, characterized in that, The adjusting the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the difference judgment result and the second default opening degree includes: If the intake air temperature difference exceeds the preset threshold, judge whether the suction port temperature of the high-pressure chamber exceeds a third preset temperature, and adjust the opening degree of the second electronic expansion valve based on the temperature judgment result; and If the intake air temperature difference does not exceed the preset threshold, determine whether the intake air temperature difference is within a preset range, and adjust the opening degrees of the first electronic expansion valve and the second electronic expansion valve based on the range judgment result and the second default opening degree.

12. A control device for a heat pump system, characterized in that, The control device of the heat pump system includes: A data acquisition module for acquiring the inlet saturation temperature and the suction port temperature of the high-pressure chamber, and the outdoor ambient temperature; A difference calculation module for determining the intake air temperature difference according to the inlet saturation temperature and the suction port temperature; and An opening degree adjustment module for adjusting the opening degree of at least one of the first electronic expansion valve and the second electronic expansion valve according to at least one of the outdoor ambient temperature and the intake air temperature difference.

13. A control equipment for a heat pump system, characterized in that, The control device of the heat pump system includes: a memory, a processor, and a control program of the heat pump system stored on the memory and executable on the processor, and the control program of the heat pump system is configured to implement the control method of the heat pump system according to any one of claims 5 to 11.

14. A storage medium, characterized in that, A control program of a heat pump system is stored on the storage medium, and when the control program of the heat pump system is executed by a processor, the control method of the heat pump system according to any one of claims 5 to 11 is implemented.

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