Flow control valve and heat pump system

Abstract

The present application relates to the field of flow control technology, and provides a flow control valve and a heat pump system. The flow control valve includes a valve body, which is internally provided with a first cavity and a second cavity that are interconnected, and the valve body is provided with a third interface, a fourth interface, and a first interface and a second interface that are respectively connected to the two ends of the first cavity; an outer piston is slidably connected to the first cavity, and the outer piston is provided with a gap that is connected to the second cavity, and the other end of the outer piston is sealed and connected to the first cavity, and one end of the outer piston is provided with a pressure balance hole that is connected to the second cavity; an inner piston is sealed and slidably connected to the mounting cavity in the outer piston, and the inner piston can switch between a compressed state and an initial state. A side piston is sealed and slidably connected to the second cavity, and the side piston can switch between a compressed state and an initial state. The flow control valve according to the embodiment of the present application realizes the switching control of the flow direction of fluids such as refrigerants, and has a simple structure and reduces costs.

Description

Technical Field

[0001] The present application relates to the technical field of flow direction control, and in particular to a flow direction control valve and a heat pump system. Background Art

[0002] When using a system with fluid flow, such as a heat pump system, it is necessary to switch and control the flow direction of the refrigerant or the corresponding fluid.

[0003] Most related technologies use two-way valves or three-way valves to switch the flow direction of fluids such as refrigerants. However, it is difficult for a valve body 1 such as a two-way valve or a three-way valve to achieve flow direction switching control of the fluid alone. In order to achieve flow direction switching control of the fluid, more auxiliary components are required, resulting in a complex system structure and high cost. Summary of the Invention

[0004] The present application aims to solve at least one of the technical problems existing in the related art. To this end, the present application proposes a flow direction control valve that realizes switching control of the flow direction of a fluid such as a refrigerant, and has a simple structure and reduces costs.

[0005] The present application also proposes a heat pump system.

[0006] The flow control valve according to the first embodiment of the present application includes:

[0007] A valve body, wherein a first cavity and a second cavity are provided therein, and the valve body is provided with a third interface, a fourth interface, and a first interface and a second interface respectively connected to two ends of the first cavity;

[0008] an outer piston, slidably connected to the first cavity, a gap being provided between one end of the outer piston and the first cavity and communicating with the second cavity, the other end of the outer piston being sealedly connected to the first cavity, and one end of the outer piston being provided with a pressure balancing hole communicating with the second cavity;

[0009] an inner piston, sealingly and slidingly connected to the mounting cavity in the outer piston, the inner piston being switchable between a compressed state isolating the first interface and the second interface and an initial state in which the first interface and the second interface are connected;

[0010] A side piston is sealingly and slidingly connected to the second cavity, and the side piston can switch between a compressed state in which the third interface is connected to the first interface and an initial state in which the third interface is connected to the fourth interface.

[0011] According to the flow control valve of the embodiment of the present application, during cooling, a pressure difference is created between the outer piston, the inner piston, and the second cavity through the gap and the pressure balance hole, and the outer piston and the inner piston are fixed by pressure. At this time, the first interface and the second interface are connected, and the third interface and the fourth interface are connected, so that the system can cool stably. During heating, the inner piston switches to a compressed state, so that the refrigerant squeezes the outer piston, causing the outer piston to move toward the second interface, so that the first cavity and the second cavity are connected, and the refrigerant generates pressure on the side piston. The side piston switches to a compressed state, so that the first interface and the third interface are connected. This achieves switching control of the flow direction of fluids such as refrigerants, and has a simple structure and reduces costs.

[0012] According to one embodiment of the present application, a first return elastic member is provided between the outer piston and the second interface.

[0013] According to one embodiment of the present application, a first sealing member is provided at one end of the outer piston close to the first interface.

[0014] According to one embodiment of the present application, a base is provided at one end of the outer piston close to the second interface, a connecting hole is provided between the base and the mounting cavity of the outer piston, and the connecting hole connects the first return elastic member and the inner piston.

[0015] According to one embodiment of the present application, a through hole matching the base is provided on the inner piston, and when the inner piston is in the compressed state, the base is sealed and connected to the through hole.

[0016] According to one embodiment of the present application, a second return elastic member is provided between an end of the inner piston close to the second interface and the outer piston.

[0017] According to one embodiment of the present application, a second sealing member is provided at one end of the inner piston close to the first interface.

[0018] According to one embodiment of the present application, a third return elastic member is provided between the side piston and the fourth interface.

[0019] The heat pump system according to the second embodiment of the present application includes the above-mentioned flow direction control valve.

[0020] According to the heat pump system of the embodiment of the present application, it includes the above-mentioned flow control valve, and therefore has all the technical effects of the above-mentioned flow control valve, which will not be repeated here.

[0021] According to one embodiment of the present application, the heat pump system includes a compressor, an external heat exchanger, an electronic expansion valve, an internal heat exchanger, a switching solenoid valve and a gas-liquid separator, one end of the compressor is connected to the first interface, the other end of the compressor is connected to the outlet of the gas-liquid separator, the external heat exchanger is connected to the second interface, the other end of the external heat exchanger is connected to one end of the electronic expansion valve, one end of the internal heat exchanger is connected to the other end of the electronic expansion valve, the other end of the internal heat exchanger is connected to the third interface, one end of the switching solenoid valve is connected to the second interface, and the other end of the switching solenoid valve and the fourth interface are both connected to the inlet of the gas-liquid separator.

[0022] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 Schematic diagram of the structure of the flow control valve provided in an embodiment of the present application;

[0025] Figure 2 Schematic diagram of the heat pump system provided in the embodiment of the present application;

[0026] Reference numerals:

[0027] 1. Valve body; 2. Outer piston; 3. Inner piston; 4. Side piston; 5. Compressor; 6. External heat exchanger; 7. Electronic expansion valve; 8. Internal heat exchanger; 9. Switch solenoid valve; 10. Gas-liquid separator; 11. First cavity; 12. Second cavity; 13. First interface; 14. Second interface; 15. Third interface; 16. Fourth interface; 21. Gap; 22. Pressure balance hole; 23. First return elastic member; 24. First sealing member; 25. Base; 26. Connecting hole; 31. Through hole; 32. Second return elastic member; 33. Second sealing member; 41. Third return elastic member. DETAILED DESCRIPTION

[0028] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0030] In the description of the embodiments of this application, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on the specific circumstances.

[0031] In the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0032] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0033] The following combination Figure 1 and Figure 2 The flow control valve of the present application is described.

[0034] According to the embodiment of the first aspect of the present application, Figure 1 As shown, the flow control valve includes

[0035] The valve body 1 is provided with a first cavity 11 and a second cavity 12 communicating with each other. The valve body 1 is provided with a third interface 15, a fourth interface 16, and a first interface 13 and a second interface 14 communicating with the two ends of the first cavity 11 respectively;

[0036] The outer piston 2 is slidably connected to the first cavity 11. A gap 21 communicating with the second cavity 12 is provided between one end of the outer piston 2 and the first cavity 11. The other end of the outer piston 2 is sealedly connected to the first cavity 11. One end of the outer piston 2 is provided with a pressure balance hole 22 communicating with the second cavity 12.

[0037] The inner piston 3 is in sealing and sliding connection with the mounting cavity in the outer piston 2. The inner piston 3 can switch between a compressed state in which the first interface 13 and the second interface 14 are isolated and an initial state in which the first interface 13 and the second interface 14 are connected.

[0038] The side piston 4 is sealed and slidably connected to the second cavity 12 , and the side piston 4 can switch between a compressed state in which the third interface 15 is connected to the first interface 13 and an initial state in which the third interface 15 is connected to the fourth interface 16 .

[0039] During use, the first port 13, second port 14, third port 15, and fourth port 16 of the valve body 1 are connected to the cooling or heating system respectively, and the outer piston 2, inner piston 3, and side piston 4 are all in the initial state. At this time, the outer piston 2 separates the first cavity 11 and the second cavity 12, the first port 13 and the second port 14 are connected, and the third port 15 is connected to the fourth port 16. When the refrigeration system is working, the refrigerant is delivered to the first port 13 and flows out from the second port 14. At this time, the pressure at the first port 13, the first cavity 11, the outer piston 2, the inner piston 3, and the second port 14 is relatively high due to the flow of refrigerant, while the pressure at the second cavity 12, the third port 15, and the fourth port 16 is relatively low. Since the gap 21 and the pressure balance hole 22 are both connected to the second cavity 12, the pressure at the gap 21 and the pressure balance hole 22 is the same as the pressure in the second cavity 12. At this time, there is a pressure difference between the outer piston 2 and the gap 21, which generates a pressure on the outer piston 2 toward the gap 21, thereby fixing the outer piston 2. There is a pressure difference between the inner piston 3 and the pressure balance hole 22, which generates a force on the inner piston 3 toward the pressure balance hole 22, thereby fixing the inner piston 3. This further fixes the outer piston 2 and the inner piston 3, ensuring that both the outer piston 2 and the inner piston 3 are in a stable state during cooling.

[0040] When switching from the refrigeration system to the heating system, due to the characteristics of the refrigerant during heating, there is no pressure difference between the outer piston 2 and the gap 21, and between the inner piston 3 and the pressure balance hole 22. When the refrigerant flows from the first interface 13 into the first cavity 11, the inner piston 3 is pressured and switched to a compressed state. At this time, the first interface 13 and the second interface 14 are isolated. Then the system continues to apply pressure to the first cavity 11, so that the outer piston 2 is also pressed toward the second interface 14, so that the first cavity 11 and the second cavity 12 are connected. The refrigerant flows into the second cavity 12, so that the side piston 4 is switched to a compressed state, so that the first interface 13 and the third interface 15 are connected. In this way, the switching control of the flow direction of the refrigerant and other fluids is realized, and the structure is simple, which reduces the cost. Compared with the traditional four-way reversing valve, the flow direction control valve of this embodiment also has lower control over internal leakage than the four-way reversing valve.

[0041] In the embodiment of the present application, an oil film sealing surface is provided between the outer piston 2 and the first cavity 11 of the valve body 1, thereby enabling the outer piston 2 to be in sealed sliding connection with the first cavity 11. However, it should be understood that the outer piston 2 and the first cavity 11 of the valve body 1 may also be connected in a sliding and sealed manner by any other suitable means, for example, by providing a sealing ring between the outer piston 2 and the first cavity 11 to achieve a sliding and sealed connection.

[0042] In the embodiment of the present application, an oil film sealing surface is provided between the inner piston 3 and the outer piston 2, thereby achieving a sealed sliding connection between the inner piston 3 and the outer piston 2. However, it should be understood that the sliding sealing connection between the inner piston 3 and the outer piston 2 can also be achieved by any other suitable means, such as by providing a sealing ring between the inner piston 3 and the outer piston 2 to achieve a sliding sealing connection.

[0043] In the embodiment of the present application, an oil film sealing surface is provided between the side piston 4 and the second cavity 12 of the valve body 1, thereby achieving a sealed sliding connection between the side piston 4 and the second cavity 12 of the valve body 1. However, it should be understood that the sealed sliding connection between the side piston 4 and the second cavity 12 can also be achieved by any other suitable means, such as by providing a sealing ring between the side piston 4 and the second cavity 12 to achieve a sliding sealed connection.

[0044] In one embodiment of the present application, Figure 1As shown, a first return elastic member 23 is provided between the outer piston 2 and the second interface 14. During use, when the system is cooling, the first return elastic member 23 is in a normal state, and the refrigerant enters the first cavity 11 through the first interface 13, and then the refrigerant flows out of the second interface 14 through the outer piston 2, the inner piston 3 and the first return elastic member 23 in sequence. When the system is heating, the refrigerant enters the first cavity 11 through the first interface 13, causing the inner piston 3 to switch to a compressed state to isolate the second interface 14 and the first cavity 11. The refrigerant continues to exert pressure on the outer piston 2, causing the outer piston 2 to move toward the second interface 14 and squeeze the second return elastic member 32. When the system stops working, that is, when the refrigerant stops being supplied to the first cavity 11, the compressed first return elastic member 23 restores its shape and simultaneously pushes the outer piston 2, causing the outer piston 2 to return to its initial position, thereby achieving automatic resetting of the outer piston 2.

[0045] In the embodiment of the present application, the first return elastic member 23 is, for example, a spring. However, it should be understood that the first return elastic member 23 may also be any other suitable elastic structural member, such as a rubber member.

[0046] In one embodiment of the present application, Figure 1 As shown, a first seal 24 is provided at one end of the outer piston 2 near the first interface 13. During use, when the outer piston 2 is near the first interface 13 when the system is cooling, the end of the outer piston 2 provided with the first seal 24 abuts against the inner wall surface of the first cavity 11. The first seal 24 can enhance the sealing performance between the outer piston 2 and the first cavity 11, preventing the refrigerant from flowing from between the outer piston 2 and the first cavity 11 into the second cavity 12. It also ensures that the pressure of the outer piston 2 is greater than the pressure in the gap 21, ensuring a pressure difference between the outer piston 2 and the gap 21. The pressure difference can be used to generate pressure on the outer piston 2, thereby fixing the outer piston 2.

[0047] In the embodiment of the present application, the first sealing member 24 is, for example, a sealing gasket, but it should be understood that the first sealing member 24 may also be any other suitable structural member with sealing performance, such as a sealing ring.

[0048] In one embodiment of the present application, Figure 1As shown, a base 25 is provided at one end of the outer piston 2 near the second port 14. A connecting hole 26 is provided between the base 25 and the mounting cavity of the outer piston 2. The connecting hole 26 connects the first return spring 23 and the inner piston 3. During use, the refrigerant during system cooling enters the first cavity 11 through the first port 13, then passes through the outer piston 2, the inner piston 3, the connecting hole 26, and the first return spring 23 before flowing out of the second port 14. When the system is heating, the refrigerant enters the first cavity 11 from the first interface 13, and the refrigerant causes the inner piston 3 to switch to a compressed state. At this time, the inner piston 3 blocks the connecting hole 26, and the connecting hole 26 is not connected to the first cavity 11. At this time, continued injection of refrigerant will increase the pressure on the outer piston 2, causing the outer piston 2 to move toward the second interface 14, so that the first cavity 11 and the second cavity 12 are connected, and then the side piston 4 switches to a compressed state under the refrigerant pressure, thereby connecting the first interface 13 and the third interface 15, realizing the switching control of the flow direction of fluids such as refrigerants, and the structure is simple, which reduces costs.

[0049] In one embodiment of the present application, Figure 1 As shown, the inner piston 3 is provided with a through hole 31 that matches the base 25. When the inner piston 3 is in the compressed state, the base 25 is sealed with the through hole 31. During use, when the inner piston 3 receives pressure and switches to the compressed state, the inner piston 3 moves toward the base 25, so that the base 25 and the through hole 31 are engaged, and the through hole 31 is sealed with the base 25. This isolates the outer piston 2 from the second interface 14. As the refrigerant continues to enter the first cavity 11, since the refrigerant cannot flow to the second interface 14 at this time, pressure is generated on the outer piston 2, causing the outer piston 2 to move toward the second interface 14. The first cavity 11 and the second cavity 12 are connected. The refrigerant flows into the second cavity 12, generating pressure on the side piston 4, causing the side piston 4 to switch to the compressed state. At this time, the first interface 13 and the third interface 15 are connected. This achieves switching control of the flow direction of fluids such as refrigerants, and the structure is simple, reducing costs.

[0050] In one embodiment of the present application, Figure 1 As shown, a second return elastic member 32 is provided between the end of the inner piston 3 near the second port 14 and the outer piston 2. During use, the second return elastic member 32 can automatically reset the inner piston 3. When the inner piston 3 is subjected to pressure, it switches to a compressed state and simultaneously squeezes the second return elastic member 32. When the inner piston 3 is no longer subjected to pressure, the squeezed second return elastic member 32 recovers its deformation and switches the inner piston 3 to its initial state.

[0051] In the embodiment of the present application, the second return elastic member 32 is, for example, a spring. However, it should be understood that the second return elastic member 32 may also be any other suitable elastic structural member, such as a rubber member.

[0052] In one embodiment of the present application, Figure 1 As shown, a second sealing member 33 is provided at one end of the inner piston 3 close to the first interface 13. During use, when the system is cooling, the refrigerant flows from the first interface 13 into the first cavity 11. At this time, the inner piston 3 is in the initial state, and one end of the inner piston 3 provided with the second sealing member 33 abuts against the outer piston 2. The second sealing member 33 can improve the sealing performance of the connection between the inner piston 3 and the outer piston 2, so that the inner piston 3 and the pressure balance hole 22 are isolated, so that the refrigerant can stably flow from the outer piston 2 and the inner piston 3 to the second interface 14, preventing the refrigerant from flowing out of the connection between the inner piston 3 and the outer piston 2. It also ensures that the pressure at the inner piston 3 is greater than the pressure balance hole 22 when the system is cooling, so that the pressure difference can generate pressure on the inner piston 3 to fix the inner piston 3.

[0053] In the embodiment of the present application, the second sealing member 33 is, for example, a sealing gasket. However, it should be understood that the second sealing member 33 may also be any other suitable structural member with sealing performance, such as a sealing ring.

[0054] In one embodiment of the present application, Figure 1 As shown, a third return elastic member 41 is disposed between the side piston 4 and the fourth port 16. During use, the third return elastic member 41 automatically resets the side piston 4. When the side piston 4 is compressed under pressure, it squeezes the third return elastic member 41. When the side piston 4 is no longer under pressure, the squeezed third return elastic member 41 recovers its deformation and simultaneously exerts a thrust on the side piston 4, returning the side piston 4 to its initial state, thereby achieving automatic reset of the side piston 4.

[0055] In the embodiment of the present application, the third return elastic member 41 is, for example, a spring. However, it should be understood that the third return elastic member 41 may also be any other suitable elastic structural member, such as a rubber member.

[0056] According to an embodiment of the second aspect of the present application, Figure 2 As shown, a heat pump system is provided, comprising the above-mentioned flow direction control valve.

[0057] The heat pump system according to the second embodiment of the present application achieves switching control of the flow direction of a refrigerant or other fluid, and has a simple structure and reduced costs. Compared to a conventional four-way reversing valve, the flow control valve of this embodiment also has lower control over internal leakage than a four-way reversing valve.

[0058] In one embodiment of the present application, the heat pump system includes a compressor 5, an external heat exchanger 6, an electronic expansion valve 7, an internal heat exchanger 8, a switch solenoid valve 9 and a gas-liquid separator 10, one end of the compressor 5 is connected to the first interface 13, the other end of the compressor 5 is connected to the outlet of the gas-liquid separator 10, the external heat exchanger 6 is connected to the second interface 14, the other end of the external heat exchanger 6 is connected to one end of the electronic expansion valve 7, one end of the internal heat exchanger 8 is connected to the other end of the electronic expansion valve 7, the other end of the internal heat exchanger 8 is connected to the third interface 15, one end of the switch solenoid valve 9 is connected to the second interface 14, and the other end of the switch solenoid valve 9 and the fourth interface 16 are both connected to the inlet of the gas-liquid separator 10. During use, when cooling, close the switch solenoid valve 9, and the refrigerant comes out from the exhaust port of the compressor 5 and flows through the flow control valve. At this time, the first interface 13 and the second interface 14 of the flow control valve are connected, and the third interface 15 and the fourth interface 16 are connected. Then the refrigerant can enter the external heat exchanger 6 to release heat. The refrigerant after heat release and condensation is throttled and reduced in pressure at the electronic expansion valve 7. The condensed refrigerant after pressure reduction absorbs heat through the internal heat exchanger 8, and then flows through the flow control valve and flows through the gas-liquid separator 10 back to the compressor 5.

[0059] During heating, the switch solenoid valve 9 is first opened, and the refrigerant comes out of the exhaust port of the compressor 5, passes through the flow control valve, then passes through the switch solenoid valve 9, and then flows through the gas-liquid separator 10 back to the compressor 5. At this time, since there is no large flow resistance source in the circuit, the refrigerant flow is large, and there is no pressure difference between the outer piston 2 and the gap 21 and between the inner piston 3 and the pressure balance hole 22. The refrigerant can push the outer piston 2 and the inner piston 3 to move, causing the flow control valve to switch. After the flow control valve is switched, the first interface 13 and the third interface 15 are connected, and the refrigerant comes out of the exhaust port of the compressor 5, passes through the flow control valve, and then enters the internal heat exchanger 8 to release heat. The refrigerant after heat release and condensation is throttled and reduced in pressure at the electronic expansion valve 7. The condensed refrigerant absorbs heat through the external heat exchanger 6, then passes through the switch solenoid valve 9, and then flows through the gas-liquid separator 10 back to the compressor 5. Furthermore, by using a flow control valve for refrigerant switching control, the heat pump system has a simple structure, low cost, improved efficiency, and is suitable for large-scale promotion. It also reduces the number of control components in the system. Compared with the heat pump system in the automotive industry, the mechanical components have high reliability and good stability.

[0060] Finally, it should be noted that the above embodiments are intended only to illustrate the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the embodiments, those skilled in the art will appreciate that various combinations, modifications, or equivalent substitutions of the technical solutions of the present application do not depart from the spirit and scope of the technical solutions of the present application and are intended to be encompassed by the claims of the present application.

Claims

1. A flow control valve, characterized in that: include A valve body, wherein a first cavity and a second cavity are provided therein, and the valve body is provided with a third interface, a fourth interface, and a first interface and a second interface respectively connected to two ends of the first cavity; an outer piston, slidably connected to the first cavity, a gap being provided between one end of the outer piston and the first cavity and communicating with the second cavity, the other end of the outer piston being sealedly connected to the first cavity, and one end of the outer piston being provided with a pressure balancing hole communicating with the second cavity; an inner piston, sealingly and slidingly connected to the mounting cavity in the outer piston, the inner piston being switchable between a compressed state isolating the first interface and the second interface and an initial state in which the first interface and the second interface are connected; A side piston is sealingly and slidingly connected to the second cavity, and the side piston can switch between a compressed state in which the third interface is connected to the first interface and an initial state in which the third interface is connected to the fourth interface.

2. The flow control valve according to claim 1, characterized in that: A first return elastic member is provided between the outer piston and the second interface.

3. The flow control valve according to claim 1, characterized in that: A first sealing member is provided at one end of the outer piston close to the first interface.

4. The flow control valve according to claim 2, characterized in that: A base is provided at one end of the outer piston close to the second interface, a connecting hole is provided between the base and the mounting cavity of the outer piston, and the connecting hole is connected to the first return elastic member and the inner piston.

5. The flow control valve according to claim 4, characterized in that: The inner piston is provided with a through hole matching the base. When the inner piston is in the compressed state, the base is sealed and connected to the through hole.

6. The flow control valve according to any one of claims 1 to 3, characterized in that: A second return elastic member is provided between one end of the inner piston close to the second interface and the outer piston.

7. The flow control valve according to any one of claims 1 to 3, characterized in that: A second sealing member is provided at one end of the inner piston close to the first interface.

8. The flow control valve according to any one of claims 1 to 3, characterized in that: A third return elastic member is provided between the side piston and the fourth interface.

9. A heat pump system, characterized in that: It comprises the flow control valve according to any one of claims 1 to 8.

10. The heat pump system according to claim 9, characterized in that The heat pump system includes a compressor, an external heat exchanger, an electronic expansion valve, an internal heat exchanger, a switch solenoid valve and a gas-liquid separator; One end of the compressor is communicated with the first interface, and the other end of the compressor is communicated with the outlet of the gas-liquid separator; The external heat exchanger is in communication with the second interface, and the other end of the external heat exchanger is in communication with one end of the electronic expansion valve; One end of the internal heat exchanger is in communication with the other end of the electronic expansion valve, and the other end of the internal heat exchanger is in communication with the third interface; One end of the switch solenoid valve is communicated with the second interface, and the other end of the switch solenoid valve and the fourth interface are both communicated with the inlet of the gas-liquid separator.

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