Heat pump system

Abstract

The heat pump system comprises a circulation loop and a liquid storage tank, the circulation loop comprises a compressor, a heat exchanger, a coil pipe, an expansion valve and a four-way valve, the coil pipe communicates with the heat exchanger through the expansion valve, and the compressor is provided with an air inlet end and an air outlet end; the four-way valve is used for selectively communicating the coil pipe or the heat exchanger with the air outlet end or the air inlet end; the coil pipe is provided with a distribution end capable of being communicated with the expansion valve and a backflow end capable of being communicated with the compressor, the liquid storage tank is connected with the backflow end through a first pipeline, and a first switch valve is arranged on the first pipeline. According to the heat pump system, the stability and the operation efficiency during mode switching are improved.

Description

Technical Field

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

[0002] In order to achieve compact structure, energy efficiency and capacity, some heat pump systems avoid installing gas-liquid separators. When the heat pump unit is shut down, the refrigerant will accumulate in some branches at the bottom of the coil under the action of gravity. When switching directly to heating, the refrigerant in the branches at the bottom of the coil will not have time to completely evaporate and will directly rush into the compressor, causing the compressor to inhale liquid, which may damage the compressor and affect system performance.

[0003] Therefore, it is necessary to provide an improved heat pump system to solve the above problems. Summary of the invention

[0004] The present application provides a heat pump system with improved operating efficiency.

[0005] The present application discloses a heat pump system, including a circulation loop and a liquid storage tank, wherein the circulation loop includes a compressor, a heat exchanger, a coil, an expansion valve and a four-way valve, wherein the coil and the heat exchanger are connected via the expansion valve, the compressor has an air inlet end and an air outlet end, and the four-way valve is used to selectively connect the coil or the heat exchanger with the air outlet end or the air inlet end; the coil has a distribution end that can be connected to the expansion valve and a reflux end that can be connected to the compressor, the liquid storage tank is connected to the reflux end via a first pipeline, and a first switch valve is provided on the first pipeline.

[0006] Furthermore, the heat pump system has a heating mode and a cooling mode. In the heating mode, the four-way valve connects the air outlet with the heat exchanger and the air inlet with the coil; in the cooling mode, the four-way valve connects the air outlet with the coil and the air inlet with the heat exchanger.

[0007] Furthermore, the heat pump system is also provided with a second pipeline, one end of the second pipeline is connected to the liquid storage tank, the other end of the second pipeline is connected to the circulation loop, and a second switch valve is provided on the second pipeline; the refrigerant in the liquid storage tank can flow into the circulation loop through the second pipeline.

[0008] Furthermore, the other end of the second pipeline is connected to the air inlet end.

[0009] Furthermore, the heat pump system is also provided with a third pipeline, one end of the third pipeline is connected to the liquid storage tank, and the other end of the third pipeline is connected to the circulation loop, and a third switch valve is provided on the third pipeline; the refrigerant in the circulation loop can flow into the liquid storage tank through the third pipeline.

[0010] Furthermore, the heat exchanger has a liquid phase end that can be connected to the expansion valve and a gas phase end that can be connected to the compressor, the two ends of the second pipeline are respectively connected to the liquid storage tank and the air intake end, and the two ends of the third pipeline are respectively connected to the liquid storage tank and the liquid phase end of the heat exchanger.

[0011] Furthermore, the heat exchanger has a liquid phase end that can be connected to the expansion valve and a gas phase end that can be connected to the compressor, the two ends of the second pipeline are respectively connected to the liquid storage tank and the distribution end, and the two ends of the third pipeline are respectively connected to the liquid storage tank and the liquid phase end of the heat exchanger.

[0012] Furthermore, the heat pump system also includes a first one-way valve and a second one-way valve, the expansion valve includes a first expansion valve and a second expansion valve, the first one-way valve is arranged between the heat exchanger and the first expansion valve, and the refrigerant in the heat pump system flows through the first expansion valve in the heating mode; the second one-way valve is arranged between the distribution end and the second expansion valve, and the refrigerant in the heat pump system flows through the second expansion valve in the cooling mode.

[0013] Furthermore, the number of the expansion valve is one, the two ends of the second pipeline are respectively connected to one end of the expansion valve and the liquid storage tank, and the two ends of the third pipeline are respectively connected to the other end of the expansion valve and the liquid storage tank.

[0014] Furthermore, the first switch valve, the second switch valve and the third switch valve are all direct-acting valves, which are used to respectively realize bidirectional flow of refrigerant in the first pipeline, the second pipeline and the third pipeline.

[0015] Furthermore, the heat pump system also includes a control device, which is used to control the opening or closing of the first switch valve, the second switch valve and the third switch valve according to the supercooling degree of the circulation loop to adjust the flow rate of the refrigerant in the circulation loop.

[0016] Furthermore, the heat pump system also includes a receiver, which is arranged between the heat exchanger and the coil; the first pipeline is connected to the bottom of the coil.

[0017] The heat pump system of the present application is provided with a liquid storage tank connected to the return end of the coil, and a first switching valve is provided on the first pipeline between the return end and the liquid storage tank to control the opening and closing of the first pipeline. When the heat pump system is shut down, the first pipeline can be connected by controlling the first switching valve, so that the liquid refrigerant accumulated at the bottom of the coil enters the liquid storage tank for storage, thereby avoiding the compressor sucking in liquid when the heat pump system switches to heating startup, helping to improve the stability of the heat pump system during mode switching, while protecting the compressor from damage, thereby improving the overall safety and operating efficiency of the heat pump system.

[0018] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the specification and, together with the description, serve to explain the principles of the specification.

[0020] Figure 1 This is a schematic diagram of the first embodiment of the heat pump system of the present application in the heating mode, and the arrow direction in the figure is the flow direction of the refrigerant.

[0021] Figure 2 This is a schematic diagram of the first embodiment of the heat pump system of the present application in the cooling mode, and the arrow direction in the figure is the flow direction of the refrigerant.

[0022] Figure 3 It is a schematic diagram of the second embodiment of the heat pump system of the present application in the heating mode.

[0023] Figure 4 It is a schematic diagram of the second embodiment of the heat pump system of the present application in cooling mode.

[0024] Figure 5 It is a schematic diagram of the third embodiment of the heat pump system of the present application in the heating mode.

[0025] Figure 6 It is a schematic diagram of the third embodiment of the heat pump system of the present application in cooling mode.

[0026] Figure 7 It is a schematic diagram of the fourth embodiment of the heat pump system of the present application in the heating mode.

[0027] Figure 8 It is a schematic diagram of the fourth embodiment of the heat pump system of the present application in cooling mode.

[0028] Fig. 9 It is a schematic diagram of the fifth embodiment of the heat pump system of the present application in the heating mode.

[0029] Fig.10It is a schematic diagram of the fifth embodiment of the heat pump system of the present application in cooling mode.

[0030] Fig.11 It is a schematic diagram of Example 6 of the heat pump system of the present application in heating mode.

[0031] Fig.12 It is a schematic diagram of the sixth embodiment of the heat pump system of the present application in cooling mode.

[0032] Description of Figure Numbers:

[0033] 10. Compressor; 11. Air inlet end; 12. Air outlet end; 20. Heat exchanger; 21. Liquid phase end; 22. Gas phase end; 30. Coil; 31. Distribution end; 32. Reflux end; 40. Expansion valve; 41. First expansion valve; 42. Second expansion valve; 50. Four-way valve; 60. Liquid storage tank; 71. First pipeline; 72. Second pipeline; 73. Third pipeline; 81. First switch valve; 82. Second switch valve; 83. Third switch valve; 91. First check valve; 92. Second check valve; 93. Filter dryer; 94. Receiver; 95. Third check valve; 96. Fourth check valve; 97. Dryer. DETAILED DESCRIPTION

[0034] Here, the technical solutions in the embodiments (or "implementations") of the present application will be described clearly and completely in conjunction with the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0035] If there are terms involving directional indications or positional relationships in the embodiments of the present application (such as up, down, left, right, front, back, inside, outside, top, bottom, center, vertical, horizontal, longitudinal, transverse, length, width, counterclockwise, clockwise, axial, radial, circumferential, etc.), such terms are only used to explain the relative positional relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings); if the specific posture changes, the directional indication or positional relationship will also change accordingly. In addition, the terms "first", "second", etc. involved in the embodiments of the present application are only used for the purpose of convenience of description and cannot be understood as indicating or implying relative importance.

[0036] Next, the embodiments of the present application are described in detail.

[0037] Embodiment 1

[0038] like Figure 1 and Figure 2 As shown, the present application provides a heat pump system, including a circulation loop and a liquid storage tank 60. A refrigerant flows in the circulation loop, and heat is transferred through the refrigerant.

[0039] The circulation loop includes a compressor 10, a heat exchanger 20, a coil 30, an expansion valve 40 and a four-way valve 50. The compressor 10 can compress low-pressure and low-temperature refrigerant gas into high-pressure and high-temperature refrigerant gas. The heat exchanger 20 and the coil 30 can be used as an evaporator or a condenser. The evaporator can absorb heat and evaporate the refrigerant liquid into refrigerant gas, and the condenser can dissipate heat and condense the refrigerant gas into refrigerant liquid. The expansion valve 40 throttles the high-pressure refrigerant liquid to a low-pressure state. The four-way valve 50 is used to realize the switching of the circulation loop between different modes.

[0040] The compressor 10, the heat exchanger 20 and the coil 30 are all connected to the four-way valve 50. The compressor 10 has an air inlet 11 and an air outlet 12, and the heat exchanger 20 and the coil 30 are both connected to the four-way valve 50. The four-way valve 50 is used to selectively connect the coil 30 or the heat exchanger 20 to the air outlet 12 or the air inlet 11. The heat exchanger 20 and the coil 30 are connected through the expansion valve 40.

[0041] The heat exchanger 20 has a liquid end 21 and a gas end 22. The liquid end 21 can be connected to the expansion valve 40, and the gas end 22 can be connected to the compressor 10 through the four-way valve 50. The coil 30 has a distribution end 31 and a return end 32. The distribution end 31 can be connected to the expansion valve 40, and the return end 32 can be connected to the compressor 10 through the four-way valve 50.

[0042] The heat pump system has a heating mode and a cooling mode. Figure 1 As shown, in the heating mode, the four-way valve 50 connects the outlet end 12 with the heat exchanger 20 and the inlet end 11 with the coil 30, the heat exchanger 20 is in the condenser mode, and the coil 30 is in the evaporator mode. The refrigerant in the circulation loop enters the heat exchanger 20 from the outlet end 12 of the compressor 10 through the four-way valve 50, condenses into refrigerant liquid in the heat exchanger 20, and then enters the expansion valve 40, then enters the coil 30 from the expansion valve 40, evaporates into refrigerant gas in the coil 30, and returns to the inlet end 11 of the compressor 10 through the four-way valve 50.

[0043] like Figure 2 As shown, in the cooling mode, the four-way valve 50 connects the gas outlet 12 with the coil 30 and the gas inlet 11 with the heat exchanger 20, the heat exchanger 20 is in the evaporator mode, and the coil 30 is in the condenser mode. The refrigerant in the circulation loop enters the coil 30 from the gas outlet 12 of the compressor 10 through the four-way valve 50, condenses into refrigerant liquid in the coil 30, and then enters the expansion valve 40, then enters the heat exchanger 20 from the expansion valve 40, evaporates into refrigerant gas in the heat exchanger 20, and returns to the gas inlet 11 of the compressor 10 through the four-way valve 50.

[0044] In this embodiment, the expansion valve 40 includes a first expansion valve 41 and a second expansion valve 42. The refrigerant in the heat pump system flows through the first expansion valve 41 in the heating mode and flows through the second expansion valve 42 in the cooling mode. This can ensure that the refrigerant has a suitable expansion process and pressure control in different modes, thereby improving the efficiency and heat exchange capacity of the heat pump system.

[0045] Furthermore, in this embodiment, the circulation loop further includes a first one-way valve 91 and a second one-way valve 92 to prevent the refrigerant from flowing back in different modes and ensure the correctness of the refrigerant flow direction. The first one-way valve 91 is arranged between the liquid phase end 21 of the heat exchanger 20 and the first expansion valve 41, and the second one-way valve 92 is arranged between the distribution end 31 of the coil 30 and the second expansion valve 42.

[0046] Furthermore, in this embodiment, the heat pump system further includes a filter-dryer 93 disposed between the heat exchanger 20 and the coil 30, which can effectively filter impurities in the refrigerant, prevent water accumulation, improve the refrigerant flow efficiency, protect key components in the heat pump system, and extend the service life of the heat pump system. Specifically, the filter-dryer 93 is connected between the first check valve 91 and the first expansion valve 41 in the heating mode, and is connected between the second check valve 92 and the second expansion valve 42 in the cooling mode.

[0047] Thus, in this embodiment, in the heating mode, the flow path of the refrigerant in the circulation circuit is "compressor 10-heat exchanger 20-first non-return valve 91-filter dryer 93-first expansion valve 41-coil 30-compressor 10". In the cooling mode, the flow path of the refrigerant in the circulation circuit is "compressor 10-coil 30-second non-return valve 92-filter dryer 93-second expansion valve 42-heat exchanger 20-compressor 10".

[0048] The liquid storage tank 60 is connected to the return end 32 of the coil 30 through a first pipeline 71, and a first switch valve 81 is provided on the first pipeline 71 to control the opening and closing of the first pipeline 71. The heat pump system also includes a control device for controlling the opening or closing of the first switch valve 81. When the first switch valve 81 is opened, the first pipeline 71 is connected. When the first switch valve 81 is closed, the first pipeline 71 is disconnected.

[0049] The first pipeline 71 is connected to the bottom of the coil 30. When the heating is stopped, the first switch valve 81 is opened, the first pipeline 71 is connected, and the liquid refrigerant accumulated at the bottom of the coil 30 can flow into the liquid storage tank 60 through the first pipeline 71 for storage. When the heat pump system needs to switch to the heating mode, there is no liquid refrigerant at the return end 32 of the coil 30, which can avoid the suction of the compressor 10 with liquid. Therefore, the heat pump system can directly start the heating mode.

[0050] The heat pump system of this embodiment is provided with a liquid storage tank 60 connected to the return end 32 of the coil 30, and a first switch valve 81 is provided on the first pipeline 71 between the return end 32 and the liquid storage tank 60 to control the opening and closing of the first pipeline 71. When the heat pump system is shut down, the first pipeline 71 can be connected by controlling the first switch valve 81, so that the liquid refrigerant accumulated at the bottom of the coil 30 enters the liquid storage tank 60 for storage, which avoids the compressor 10 sucking air with liquid when the heat pump system switches to heating startup, which helps to improve the stability of the heat pump system when switching modes, and at the same time protects the compressor 10 from damage, thereby improving the overall safety and operation efficiency of the heat pump system.

[0051] Embodiment 2

[0052] like Figure 3 and Figure 4 As shown, in the second embodiment, the circulation circuit connection mode of the heat pump system and the flow path of the refrigerant in the cooling and heating modes are basically the same as those in the first embodiment.

[0053] On the basis of the first embodiment, the heat pump system is further provided with a second pipeline 72. One end of the second pipeline 72 is connected to the liquid storage tank 60, and the other end of the second pipeline 72 is connected to the circulation loop, and the refrigerant in the liquid storage tank 60 can flow into the circulation loop through the second pipeline 72. A second switch valve 82 is provided on the second pipeline 72 to control the on-off of the second pipeline 72. When the second switch valve 82 is opened, the second pipeline 72 is connected. When the second switch valve 82 is closed, the second pipeline 72 is disconnected.

[0054] In this embodiment, the volume of the liquid storage tank 60 is 20%-50% of the total refrigerant amount in the heat pump system. One end of the second pipeline 72 is connected to the bottom of the liquid storage tank 60, and the other end is connected to the air inlet end 11 of the compressor 10. When the second switch valve 82 is opened, the refrigerant stored in the liquid storage tank 60 can enter the compressor 10 through the second pipeline 72.

[0055] The first switch valve 81 can be opened in stages to allow the refrigerant in the circulation loop to intermittently enter the liquid storage tank 60. The second switch valve 82 can also be opened in stages to allow the refrigerant in the liquid storage tank 60 to intermittently return to the circulation loop.

[0056] When the heat pump system is in the cooling shutdown stage, the first switch valve 81 is closed, the second switch valve 82 is opened, and the liquid storage tank 60 has no substantial function. When the heat pump system is in the cooling mode, under the condition of small load and low outlet water temperature, the first switch valve 81 is opened in stages, the second switch valve 82 is opened, and the liquid storage tank 60 can be used as an intermediate channel to receive the refrigerant from the coil 30 and return the refrigerant to the compressor 10.

[0057] When the heat pump system is in the heating shutdown stage, the first switch valve 81 and the second switch valve 82 are both open, and the liquid storage tank 60 receives the refrigerant at the bottom of the coil 30 to prevent the compressor 10 from starting with liquid when switching to the heating mode. When the heat pump system is in the heating mode, the first switch valve 81 is opened in stages, and the second switch valve 82 is opened. The liquid storage tank 60 can be used as an intermediate channel to receive the refrigerant from the coil 30 while returning the refrigerant to the compressor 10.

[0058] In order to gasify the refrigerant in the second pipeline 72, the second pipeline 72 can be attached to a high-temperature pipeline, such as an exhaust pipe, a liquid tank, etc. A regenerator can also be provided in the heat pump system, and the second pipeline 72 is connected to the regenerator to achieve gasification of the refrigerant.

[0059] Further, the heat pump system further includes a receiver 94 disposed between the heat exchanger 20 and the coil 30. Specifically, the receiver 94 is disposed between the heat exchanger 20 and the first one-way valve 91, and can receive or release refrigerant to adjust the refrigerant flow in the circulation loop.

[0060] By providing a second pipeline 72 connecting the liquid storage tank 60 and the compressor 10, a smooth reflux of the refrigerant can be achieved, the flow of the refrigerant can be effectively regulated, and load fluctuations of the compressor 10 caused by an unbalanced amount of refrigerant can be avoided, thereby making the effect of the heat pump system more stable and reliable.

[0061] Embodiment 3

[0062] like Figure 5 and Figure 6 As shown, in the third embodiment, the circulation circuit connection mode of the heat pump system and the flow path of the refrigerant in the cooling and heating modes are basically the same as those in the second embodiment.

[0063] On the basis of the second embodiment, the heat pump system is further provided with a third pipeline 73, which cooperates with the first pipeline 71 and the second pipeline 72 to realize the dynamic liquid storage function of the liquid storage tank 60. One end of the third pipeline 73 is connected to the liquid storage tank 60, and the other end is connected to the circulation loop. The refrigerant in the circulation loop can flow into the liquid storage tank 60 through the third pipeline 73. A third switch valve 83 is provided on the third pipeline 73 to control the on and off of the third pipeline 73. When the third switch valve 83 is opened, the third pipeline 73 is connected. When the third switch valve 83 is closed, the third pipeline 73 is disconnected.

[0064] The first switch valve 81, the second switch valve 82 and the third switch valve 83 can be set as direct-acting valves to respectively enable the refrigerant to flow in both directions in the first pipeline 71, the second pipeline 72 and the third pipeline 73. The control device controls the opening or closing of the first switch valve 81, the second switch valve 82 and the third switch valve 83 according to the subcooling degree of the circulation circuit to adjust the flow rate of the refrigerant in the circulation circuit.

[0065] In this embodiment, the volume of the liquid storage tank 60 is 50%-70% of the total refrigerant amount in the heat pump system. The two ends of the second pipeline 72 are respectively connected to the liquid storage tank 60 and the air inlet end 11 of the compressor 10, and the two ends of the third pipeline 73 are respectively connected to the liquid storage tank 60 and the liquid phase end 21 of the heat exchanger 20.

[0066] When the heat pump system is in the refrigeration shutdown stage, the third switch valve 83 is opened, and the refrigerant at the liquid phase end 21 of the heat exchanger 20 can flow into the liquid storage tank 60 through the third pipeline 73, so as to avoid the compressor 10 starting with liquid when switching to the refrigeration mode. When the heat pump system is in the refrigeration mode, the third switch valve 83 is closed, the second switch valve 82 is opened, and the refrigerant in the liquid storage tank 60 can return to the refrigeration system through the second pipeline 72.

[0067] At this time, the refrigerant flow in the circulation loop can be dynamically adjusted by controlling the opening and closing of the first switch valve 81, the second switch valve 82 and the third switch valve 83, so as to adjust the degree of supercooling. For example, the refrigerant can be added to the liquid storage tank 60 by opening the first switch valve 81 (the refrigerant is gas at this time, but it can be condensed into liquid and stored in the liquid storage tank 60 during the flow process), or the refrigerant in the liquid storage tank 60 can be discharged back to the circulation loop by opening the third switch valve 83.

[0068] When the heat pump system is in the heating shutdown stage, the first switch valve 81 is opened, and the liquid storage tank 60 receives the refrigerant at the bottom of the coil 30 to prevent the compressor 10 from starting with liquid when switching to the heating mode. When the heat pump system is in the heating mode, the second switch valve 82 is closed, and the third switch valve 83 is opened, and the refrigerant at the liquid end 21 of the heat exchanger 20 can flow into the liquid storage tank 60 through the third pipeline 73.

[0069] At this time, when it is necessary to adjust the subcooling degree of the condenser (heat exchanger 20 in this mode), the refrigerant flow in the circulation loop can be dynamically adjusted by controlling the opening and closing of the first switch valve 81, the second switch valve 82 and the third switch valve 83, so as to adjust the subcooling degree. For example, the refrigerant can be added to the liquid storage tank 60 by opening the third switch valve 83, or the refrigerant in the liquid storage tank 60 can be discharged back to the circulation loop by opening the second switch valve 82.

[0070] In this embodiment, by providing a third pipeline 73 connecting the liquid storage tank 60 and the heat exchanger 20, the refrigerant at the liquid phase end 21 of the heat exchanger 20 can be stored in the liquid storage tank 60 in the heating mode. By cooperating with the first pipeline 71 and the second pipeline 72, dynamic adjustment of the refrigerant flow in the circulation loop is achieved, thereby improving the working energy efficiency of the heat pump system.

[0071] Embodiment 4

[0072] like Figure 7 and Figure 8 As shown, in the fourth embodiment, the circulation circuit connection mode of the heat pump system and the flow path of the refrigerant in the cooling and heating modes are basically the same as those in the third embodiment.

[0073] Different from the third embodiment, in this embodiment, the two ends of the second pipeline 72 are respectively connected to the liquid storage tank 60 and the distribution end 31 of the coil 30. When the second switch valve 82 is opened, the refrigerant in the liquid storage tank 60 can return to the distribution end 31 of the coil 30 through the second pipeline 72.

[0074] When the heat pump system is in the cooling shutdown stage, the first switch valve 81 is closed, the second switch valve 82 is opened, and the liquid storage tank 60 has no substantial function. When the heat pump system is in the cooling mode, under the condition of small load and low outlet water temperature, the first switch valve 81 is opened in stages, the third switch valve 83 is opened, and the liquid storage tank 60 can be used as an intermediate channel to receive the refrigerant from the coil 30 and return the refrigerant to the circulation loop.

[0075] When the heat pump system is in the heating startup stage, the first switch valve 81 is closed, the second switch valve 82 is closed, and the third switch valve 83 is opened. The liquid storage tank 60 receives excess refrigerant from the heat exchanger 20 to reduce the refrigerant flow in the circulation loop and avoid a high-pressure alarm.

[0076] When the heat pump system is in heating mode, the opening and closing of the first switch valve 81, the second switch valve 82 and the third switch valve 83 can be controlled according to the subcooling degree of the condenser (heat exchanger 20 in this mode) and the opening degree of the first expansion valve 41, so as to dynamically adjust the refrigerant flow in the circulation loop. When the subcooling degree of the condenser is high or the opening degree of the first expansion valve 41 is small, the amount of refrigerant in the circulation loop needs to be reduced, and the third switch valve 83 can be opened to allow the excess refrigerant in the circulation loop to enter the liquid storage tank 60. When the subcooling degree of the condenser is low or the opening degree of the first expansion valve 41 is large, the amount of refrigerant in the circulation loop needs to be increased, and the refrigerant can be added to the circulation loop from the liquid storage tank 60 by opening the second switch valve 82.

[0077] By connecting the second pipeline 72 to the liquid storage tank 60 and the distribution end 31 of the coil 30 respectively, in the heating mode, the liquid refrigerant discharged from the second pipeline 72 can be quickly evaporated in the coil 30, so that the refrigerant in the liquid storage tank 60 can be quickly discharged, thereby improving the working efficiency of the heat pump system.

[0078] Embodiment 5

[0079] like Fig. 9 and Fig.10As shown, different from the fourth embodiment, in this embodiment, the number of the expansion valve 40 is one. The second pipeline 72 and the third pipeline 73 are respectively connected to the inlet end and the outlet end of the expansion valve 40. The two ends of the second pipeline 72 are respectively connected to one end of the expansion valve 40 and the liquid storage tank 60, and the two ends of the third pipeline 73 are respectively connected to the other end of the expansion valve 40 and the liquid storage tank 60.

[0080] The heat pump system of this embodiment further includes a third one-way valve 95 and a fourth one-way valve 96 disposed between the heat exchanger 20 and the coil 30. The third one-way valve 95 is located between the expansion valve 40 and the distribution end 31 of the coil 30, and the fourth one-way valve 96 is located between the expansion valve 40 and the liquid phase end 21 of the heat exchanger 20.

[0081] Thus, in this embodiment, in the heating mode, the flow path of the refrigerant in the circulation loop is "compressor 10-heat exchanger 20-first check valve 91-filter dryer 93-expansion valve 40-third check valve 95-coil 30-compressor 10". In the cooling mode, the flow path of the refrigerant in the circulation loop is "compressor 10-coil 30-second check valve 92-filter dryer 93-expansion valve 40-fourth check valve 96-heat exchanger 20-compressor 10".

[0082] This embodiment reduces the cost by simplifying the number of one-way valves 40, and the overall structure of the heat pump system is more compact and occupies less space.

[0083] Embodiment 6

[0084] like Fig.11 and Fig.12 As shown, different from the fifth embodiment, the one-way valve is not provided in this embodiment. A dryer 97 is provided between the liquid end 21 of the heat exchanger 20 and the expansion valve 40 , and a filter dryer 93 is provided between the liquid end 21 of the coil 30 and the expansion valve 40 .

[0085] In heating mode, the refrigerant circulation path in the circulation loop is "compressor 10-heat exchanger 20-dryer 97-expansion valve 40-filter dryer 93-coil 30-compressor 10". In cooling mode, the refrigerant circulation path in the circulation loop is "compressor 10-coil 30-filter dryer 93-expansion valve 40-dryer 97-heat exchanger 20-compressor 10".

[0086] The two ends of the second pipeline 72 are respectively connected to the liquid storage tank 60 and the distribution end 31 of the coil 30, and the two ends of the third pipeline 73 are respectively connected to the liquid storage tank 60 and the liquid phase end 21 of the heat exchanger 20. When the refrigeration is stopped, the third switch valve 83 can be opened to allow the refrigerant of the heat exchanger 20 to flow into the liquid storage tank 60 through the third pipeline 73, thereby reducing the risk of liquid carryover when the refrigeration is started.

[0087] The heat pump system of the present application is provided with a liquid storage tank 60 connected to the return end 32 of the coil 30, and a first switch valve 81 is provided on the first pipeline 71 between the return end 32 and the liquid storage tank 60 to control the opening and closing of the first pipeline 71. When the heat pump system is shut down, the first pipeline 71 can be connected by controlling the first switch valve 81, so that the liquid refrigerant accumulated at the bottom of the coil 30 enters the liquid storage tank 60 for storage, which avoids the compressor 10 sucking air with liquid when the heat pump system switches to heating startup, helps to improve the stability of the heat pump system when switching modes, and protects the compressor 10 from damage, thereby improving the overall safety and operating efficiency of the heat pump system.

[0088] It should be noted that the technical solutions or technical features described in the above embodiments can be combined or supplemented with each other without causing conflicts. The scope of protection of this application is not limited to the precise structures described in the above embodiments and shown in the drawings; all modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A heat pump system, characterized in that: It includes a circulation loop and a liquid storage tank. The circulation loop includes a compressor, a heat exchanger, a coil, an expansion valve and a four-way valve. The coil and the heat exchanger are connected through the expansion valve. The compressor has an air inlet end and an air outlet end. The four-way valve is used to selectively connect the coil or the heat exchanger with the air outlet end or the air inlet end. The coil has a distribution end that can be connected to the expansion valve and a reflux end that can be connected to the compressor. The liquid storage tank is connected to the reflux end through a first pipeline. A first switch valve is provided on the first pipeline.

2. The heat pump system according to claim 1, characterized in that: The heat pump system has a heating mode and a cooling mode. In the heating mode, the four-way valve connects the air outlet with the heat exchanger and the air inlet with the coil; in the cooling mode, the four-way valve connects the air outlet with the coil and the air inlet with the heat exchanger.

3. The heat pump system according to claim 2, characterized in that: The heat pump system is also provided with a second pipeline, one end of which is connected to the liquid storage tank, and the other end of the second pipeline is connected to the circulation loop, and a second switch valve is provided on the second pipeline; the refrigerant in the liquid storage tank can flow into the circulation loop through the second pipeline.

4. The heat pump system according to claim 3, characterized in that: The other end of the second pipeline is connected to the air inlet end.

5. The heat pump system according to claim 3, characterized in that: The heat pump system is also provided with a third pipeline, one end of which is connected to the liquid storage tank, and the other end of which is connected to the circulation loop. A third switch valve is provided on the third pipeline; the refrigerant in the circulation loop can flow into the liquid storage tank through the third pipeline.

6. The heat pump system according to claim 5, characterized in that: The heat exchanger has a liquid phase end that can be connected to the expansion valve and a gas phase end that can be connected to the compressor. The two ends of the second pipeline are respectively connected to the liquid storage tank and the air inlet end, and the two ends of the third pipeline are respectively connected to the liquid storage tank and the liquid phase end of the heat exchanger.

7. The heat pump system according to claim 5, characterized in that: The heat exchanger has a liquid phase end that can be connected to the expansion valve and a gas phase end that can be connected to the compressor. The two ends of the second pipeline are respectively connected to the liquid storage tank and the distribution end, and the two ends of the third pipeline are respectively connected to the liquid storage tank and the liquid phase end of the heat exchanger.

8. The heat pump system according to any one of claims 3 to 7, characterized in that: The heat pump system also includes a first one-way valve and a second one-way valve, and the expansion valve includes a first expansion valve and a second expansion valve, the first one-way valve is arranged between the heat exchanger and the first expansion valve, and the refrigerant in the heat pump system flows through the first expansion valve in the heating mode; the second one-way valve is arranged between the distribution end and the second expansion valve, and the refrigerant in the heat pump system flows through the second expansion valve in the cooling mode.

9. The heat pump system according to claim 5, characterized in that: The number of the expansion valve is one, the two ends of the second pipeline are respectively connected to one end of the expansion valve and the liquid storage tank, and the two ends of the third pipeline are respectively connected to the other end of the expansion valve and the liquid storage tank.

10. The heat pump system according to claim 5, characterized in that: The first switch valve, the second switch valve and the third switch valve are all direct-acting valves, which are used to realize the bidirectional flow of the refrigerant in the first pipeline, the second pipeline and the third pipeline respectively.

11. The heat pump system according to claim 5, characterized in that: The heat pump system also includes a control device, which is used to control the opening or closing of the first switch valve, the second switch valve and the third switch valve according to the supercooling degree of the circulation loop to adjust the flow rate of the refrigerant in the circulation loop.

12. The heat pump system according to claim 1, characterized in that: The heat pump system further includes a receiver, which is arranged between the heat exchanger and the coil; the first pipeline is connected to the bottom of the coil.

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