Four-pipe heat pump system and air conditioner

Abstract

The utility model belongs to the technical field of air conditioners, and discloses a four-pipe heat pump system and an air conditioner, the four-pipe heat pump system comprises a heat exchange unit composed of a compressor, a reversing four-way valve, a reversing three-way valve, a first heat exchanger, a second heat exchanger, a third heat exchanger and an expansion valve, an oil return passage communicated with the compressor is constructed in the four-pipe heat pump system, so that lubricating oil accumulated in the first heat exchanger, the second heat exchanger or the third heat exchanger which does not participate in work flows back to the compressor, and the oil return unit is connected with the compressor. In addition, the refrigerant in the oil return passage can carry a large amount of lubricating oil which is not separated due to evaporation to return to the compressor, so that oil supplementation to the compressor is achieved, the liquid level switch controls on-off of the oil return electromagnetic valve at any time according to the liquid level of the oil quantity in the compressor, the oil return response speed is increased, and the service life of the compressor is prolonged. And compressor damage caused by oil return response lag is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of air conditioning, in particular to a four-pipe heat pump system and an air conditioner. Background Art

[0002] In air conditioners, the compressor is an important power device. It compresses the refrigerant to turn it into a high-temperature and high-pressure gas and participate in the heat pump system. The compressor needs to be lubricated with lubricating oil during operation, otherwise the compressor will be "burned" due to wear and overheating. However, in current air conditioners, whether in cooling mode or heating mode, when the mixed liquid of liquid refrigerant and lubricating oil enters the evaporator, the liquid refrigerant gradually evaporates in the evaporator, causing the refrigerant to become a low-temperature and low-pressure gas with a certain degree of superheat. Because the temperature is low, most of the lubricating oil is still liquid, causing the refrigerant to separate from the lubricating oil and gradually accumulate in the system pipeline, resulting in a gradual reduction of the lubricating oil in the compressor, and eventually the compressor is damaged due to lack of lubricating oil.

[0003] Currently, there are two common ways to solve the problem of compressor oil return. One is to use the high and low frequencies of the compressor or the increase and decrease of the load of the compressor to form a pressure difference in the system for oil return. However, returning oil by adjusting the frequency through high and low frequencies and increase and decrease of load will affect the water temperature fluctuation of the system. Long-term fluctuation of water temperature will cause abnormal ambient temperature control on the indoor side, which will give customers a bad experience of using air conditioners. The other is to use switching modes for oil return. The opening of the electronic expansion valve in the corresponding mode allows the oil of the air-conditioning system to be drawn back to the compressor, thereby achieving the oil return effect. Therefore, in addition to setting the expansion valve for heating and the expansion valve for cooling, two additional expansion valves for mode conversion are required.

[0004] The oil return by mode conversion is not only costly because four expansion valves are set in one unit, but also because this mode is a passive measure when the compressor is short of oil, the compressor may be damaged before the expansion valve responds, resulting in a slow response speed. Utility Model Content

[0005] The utility model aims to provide a four-pipe heat pump system and air conditioner with low cost and fast response speed.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] In one aspect, a four-pipe heat pump system is provided, the four-pipe heat pump system comprising:

[0008] A heat exchange unit, the heat exchange unit comprising a compressor, a reversing four-way valve, a reversing three-way valve, a first heat exchanger, a second heat exchanger, a third heat exchanger and an expansion valve, the reversing four-way valve can selectively connect the inlet or outlet of the compressor to the first heat exchanger or the second heat exchanger, the inlet of the expansion valve is connected to the first heat exchanger or the second heat exchanger, one end of the reversing three-way valve is connected to the outlet of the expansion valve, and the other end is connected to the inlet of the first heat exchanger or the third heat exchanger, and the outlet of the third heat exchanger is connected to the inlet of the compressor;

[0009] An oil return unit, the oil return unit includes a liquid level switch and an oil return solenoid valve, one end of the oil return solenoid valve is connected to the pipeline between the reversing three-way valve and the first heat exchanger, and the other end is connected to the pipeline between the reversing three-way valve and the third heat exchanger. The liquid level switch is arranged in the compressor and is used to detect the liquid level of the oil in the compressor to control the on and off of the oil return solenoid valve.

[0010] Optionally, the heat exchange unit also includes a cooling container, a first one-way valve and an angle valve. The cooling container stores a coolant for heat exchange with the refrigerant in the compressor. One end of the cooling container is connected to the first heat exchanger, and the other end is connected to the inlet of the first one-way valve. The angle valve is used to connect the outlet of the first one-way valve with the inlet of the expansion valve.

[0011] Optionally, the heat exchange unit also includes a liquid reservoir and a second one-way valve, the second heat exchanger includes an air circuit interface and a liquid circuit outlet, the air circuit interface is connected to the reversing four-way valve, the liquid circuit outlet is connected to the liquid reservoir, the liquid reservoir is connected to the inlet of the second one-way valve, and the outlet of the second one-way valve is connected to the angle valve.

[0012] Optionally, the second heat exchanger further includes a liquid circuit inlet, and the heat exchange unit further includes a third one-way valve, the outlet of the third one-way valve is connected to the liquid circuit inlet, and the inlet of the third one-way valve is connected to the reversing three-way valve.

[0013] Optionally, the heat exchange unit further includes a fourth one-way valve, an inlet of the fourth one-way valve is connected in parallel with an inlet of the third one-way valve at the outlet of the reversing three-way valve, and an outlet of the fourth one-way valve is connected to the first heat exchanger.

[0014] Optionally, the heat exchange unit further includes a drying filter, and the drying filter is arranged between the angle valve and the inlet of the expansion valve.

[0015] Optionally, the first heat exchanger is a fin heat exchanger.

[0016] Optionally, the second heat exchanger further comprises a first medium inlet and a first medium outlet, wherein the first medium inlet is used to introduce the liquid to be heated into the second heat exchanger, and the first medium outlet is used to output the liquid to be heated.

[0017] Optionally, the third heat exchanger further includes a second medium inlet and a second medium outlet, wherein the second medium inlet is used to introduce the liquid to be cooled into the third heat exchanger, and the second medium outlet is used to output the liquid to be cooled.

[0018] On the other hand, an air conditioner is provided, comprising the four-pipe heat pump system as described in any one of the above items.

[0019] Beneficial effects of the utility model:

[0020] The utility model provides a four-pipe heat pump system, which provides an oil return unit composed of a liquid level switch and an oil return solenoid valve, and uses the oil return solenoid valve to connect the pipeline between the reversing three-way valve and the first heat exchanger and the pipeline between the reversing three-way valve and the third heat exchanger, and enables the liquid level switch to realize the on and off of the oil return solenoid valve according to the liquid level of the oil in the compressor, thereby constructing an oil return passage that is on and off according to the liquid level height. On the one hand, whether the first heat exchanger works with the second heat exchanger, or the first heat exchanger works with the third heat exchanger, or the second heat exchanger works with the third heat exchanger, a part of the refrigerant can enter the first heat exchanger, the second heat exchanger or the third heat exchanger that is not involved in the work through the oil return passage, and carry the lubricating oil accumulated therein back to the compressor, so as to complete the oil replenishment of the compressor. On the other hand, When the refrigerant in the compressor enters the first heat exchanger for evaporation or the third heat exchanger for evaporation, the oil return passage can be used to directly return a portion of the refrigerant carrying a large amount of lubricating oil that has not been separated due to evaporation to the compressor before the refrigerant evaporates, thereby replenishing the oil of the compressor, and the liquid level switch controls the on and off of the oil return solenoid valve according to the oil level in the compressor at any time, thereby increasing the speed of the oil return response and avoiding damage to the compressor due to delayed oil return response. By setting a reversing three-way valve, one side of the expansion valve can be connected to the first heat exchanger or the second heat exchanger, and the other side can be connected to the first heat exchanger or the third heat exchanger through the reversing three-way valve, so that the four-pipe heat pump system only needs one expansion valve to complete the mode conversion, without the need to set up multiple expansion valves, thereby reducing costs.

[0021] The utility model provides an air conditioner, which, by applying the above-mentioned four-pipe heat pump system, not only reduces the cost, but also avoids the compressor from being damaged due to lack of lubricating oil due to long-term use, thereby indirectly increasing the service life of the air conditioner and reducing the maintenance cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a hydraulic principle diagram of a four-pipe heat pump system provided by the utility model;

[0023] Figure 2 yes Figure 1 A magnified view of part A;

[0024] Figure 3 yes Figure 1 A magnified view of part B;

[0025] Figure 4 The utility model provides a connection diagram of a compressor and a liquid level switch in a four-pipe heat pump system.

[0026] In the figure:

[0027] 101, compressor; 102, reversing four-way valve; 103, reversing three-way valve; 104, first heat exchanger; 105, second heat exchanger; 106, third heat exchanger; 107, expansion valve; 108, cooling container; 109, first non-return valve; 110, angle valve; 111, liquid storage tank; 112, second non-return valve; 113, third non-return valve; 114, fourth non-return valve; 115, drying filter;

[0028] 201. Liquid level switch; 202. Oil return solenoid valve. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0030] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0032] In the description of this embodiment, the terms "upper", "lower", "right", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0033] In air conditioners, the compressor is an important power device. It compresses the refrigerant to turn it into a high-temperature and high-pressure gas and participate in the heat pump system. The compressor needs to be lubricated with lubricating oil during operation, otherwise the compressor will be "burned" due to wear and overheating. However, in current air conditioners, whether in cooling mode or heating mode, when the mixed liquid of liquid refrigerant and lubricating oil enters the evaporator, the liquid refrigerant gradually evaporates in the evaporator, causing the refrigerant to become a low-temperature and low-pressure gas with a certain degree of superheat. Because the temperature is low, most of the lubricating oil is still liquid, causing the refrigerant to separate from the lubricating oil and gradually accumulate in the system pipeline, resulting in a gradual reduction of the lubricating oil in the compressor, and eventually the compressor is damaged due to lack of lubricating oil.

[0034] Currently, there are two common ways to solve the problem of compressor oil return. One is to use the high and low frequencies of the compressor or the increase and decrease of the load of the compressor to form a pressure difference in the system for oil return. However, returning oil by adjusting the frequency through high and low frequencies and increase and decrease of load will affect the water temperature fluctuation of the system. Long-term fluctuation of water temperature will cause abnormal ambient temperature control on the indoor side, which will give customers a bad experience of using air conditioners. The other is to use switching modes for oil return. The opening of the electronic expansion valve in the corresponding mode allows the oil of the air-conditioning system to be drawn back to the compressor, thereby achieving the oil return effect. Therefore, in addition to setting the expansion valve for heating and the expansion valve for cooling, two additional expansion valves for mode conversion are required.

[0035] The oil return by mode conversion is not only costly because four expansion valves are set in one unit, but also because this mode is a passive measure when the compressor is short of oil, the compressor may be damaged before the expansion valve responds, resulting in a slow response speed.

[0036] Therefore, in order to improve the response speed to the oil replenishment of the compressor, realize the timely oil replenishment of the compressor, and reduce the manufacturing cost, this embodiment provides a four-pipe heat pump system.

[0037] like Figures 1 to 4 As shown, the four-pipe heat pump system includes a heat exchange unit and an oil return unit. The heat exchange unit includes a compressor 101, a reversing four-way valve 102, a reversing three-way valve 103, a first heat exchanger 104, a second heat exchanger 105, a third heat exchanger 106 and an expansion valve 107. The reversing four-way valve 102 can selectively connect the inlet or outlet of the compressor 101 to the first heat exchanger 104 or the second heat exchanger 105, the inlet of the expansion valve 107 is connected to the first heat exchanger 104 or the second heat exchanger 105, and one end of the reversing three-way valve 103 is connected to the outlet of the expansion valve 107. , and the other end is connected to the inlet of the first heat exchanger 104 or the third heat exchanger 106. The outlet of the third heat exchanger 106 is connected to the inlet of the compressor 101. The oil return unit includes a liquid level switch 201 and an oil return solenoid valve 202. One end of the oil return solenoid valve 202 is connected to the pipeline between the reversing three-way valve 103 and the first heat exchanger 104, and the other end is connected to the pipeline between the reversing three-way valve 103 and the third heat exchanger 106. The liquid level switch 201 is arranged in the compressor 101 and is used to detect the liquid level of the oil in the compressor 101 to control the on and off of the oil return solenoid valve 202.

[0038] By setting an oil return unit composed of a liquid level switch 201 and an oil return solenoid valve 202, the oil return solenoid valve 202 is used to connect the pipeline between the reversing three-way valve 103 and the first heat exchanger 104 and the pipeline between the reversing three-way valve 103 and the third heat exchanger 106, and the liquid level switch 201 is used to realize the on and off of the oil return solenoid valve 202 according to the liquid level of the oil in the compressor 101, thereby constructing an oil return passage that is turned on and off according to the liquid level height. On the one hand, whether it is the first heat exchanger 104 or the second When the heat exchanger 105 cooperates with each other, or when the first heat exchanger 104 cooperates with the third heat exchanger 106, or when the second heat exchanger 105 cooperates with the third heat exchanger 106, a part of the refrigerant can enter the first heat exchanger 104, the second heat exchanger 105 or the third heat exchanger 106 that is not involved in the work through the oil return passage, and carry the lubricating oil accumulated therein back to the compressor 101, so as to complete the oil replenishment of the compressor 101. On the other hand, when the compressor Whether the refrigerant in the compressor 101 enters the first heat exchanger 104 for evaporation or the third heat exchanger 106 for evaporation, the oil return passage can be used to directly return a portion of the refrigerant carrying a large amount of lubricating oil that has not been separated due to evaporation to the compressor 101 before the refrigerant is evaporated, thereby replenishing the oil of the compressor 101, and the liquid level switch 201 controls the on and off of the oil return solenoid valve 202 at any time according to the oil level in the compressor 101, thereby improving the speed of the oil return response and avoiding damage to the compressor 101 due to the lag of the oil return response. In addition, by setting the reversing three-way valve 103, one side of the expansion valve 107 can be connected to the first heat exchanger 104 or the second heat exchanger 105, and the other side is connected to the first heat exchanger 104 or the third heat exchanger 106 through the reversing three-way valve 103, so that the four-pipe heat pump system only needs one expansion valve 107 to complete the mode conversion, without setting multiple expansion valves 107, thereby reducing the cost.

[0039] In the four-pipe heat pump system, the first heat exchanger 104 is used to achieve heat exchange between the refrigerant and the outside air. Therefore, the first heat exchanger 104 is a condenser when the refrigerant temperature is high, and is an evaporator when the refrigerant temperature is low. The second heat exchanger 105 is used as a condenser in the four-pipe heat pump system. By passing a high-temperature refrigerant, the liquid passed into the second heat exchanger 105 is heated. The third heat exchanger 106 is used as an evaporator in the four-pipe heat pump system. By passing a low-temperature refrigerant, the liquid passed into the third heat exchanger 106 is cooled. By using the first heat exchanger 104, the second heat exchanger 105 and the third heat exchanger 106 in different combinations, the four-pipe heat pump system has a cooling mode, a heating mode and a heat recovery mode. Figure 2 , Figure 3 As shown, for the convenience of description, the four interfaces of the reversing four-way valve 102 are named a, b, c, and d, and the three interfaces of the reversing three-way valve 103 are named e, f, and g. The specific operation processes of the three modes are as follows:

[0040] When the four-pipe heat pump system is in the cooling mode, the high-temperature and high-pressure refrigerant gas compressed by the compressor 101 carries the lubricating oil and flows out from the outlet of the compressor 101, enters through the a interface of the reversing four-way valve 102, and flows out from the b interface to enter the first heat exchanger 104. Since the refrigerant is in a high-temperature and high-pressure state at this time, the outside air temperature is lower than the refrigerant temperature, so the refrigerant condenses and releases heat in the first heat exchanger 104 and becomes a low-temperature and high-pressure liquid. Then, it flows out from the first heat exchanger 104 and enters the expansion valve 107, and the refrigerant is throttled and depressurized. At this time, the refrigerant becomes a low-temperature and low-pressure liquid. Then, it enters through the e interface of the reversing three-way valve 103, and flows out from the f interface to enter the third heat exchanger 106. At this time, a high-temperature liquid is introduced into the third heat exchanger 106, and the refrigerant evaporates and absorbs heat to cool the liquid in the third heat exchanger 106, and the refrigerant becomes a low-temperature and low-pressure gas. Then, the low-temperature and low-pressure refrigerant flows back to the compressor 101 to continue the cycle. During operation, the lubricating oil will not only adhere to the first heat exchanger 104 with the flow of the refrigerant, but also after completing the evaporation operation in the third heat exchanger 106, due to the low temperature, most of the lubricating oil is still in liquid form. At this time, a large amount of lubricating oil will be separated from the refrigerant, causing the lubricating oil to accumulate in the third heat exchanger 106.

[0041] When the four-pipe heat pump system is in heating mode, the high-temperature and high-pressure refrigerant gas compressed by the compressor 101 carries the lubricating oil and flows out from the outlet of the compressor 101, enters through the a interface of the reversing four-way valve 102, and flows out from the d interface into the second heat exchanger 105. At this time, low-temperature liquid is introduced into the second heat exchanger 105. Since the refrigerant is in a high-temperature and high-pressure state at this time, the refrigerant condenses and releases heat in the second heat exchanger 105, becomes a low-temperature and high-pressure liquid, and heats the liquid in the second heat exchanger 105, and then the second heat exchanger 105 is heated. The refrigerant flows out of the heat exchanger 105 and enters the expansion valve 107, where the refrigerant is throttled and depressurized. At this time, the refrigerant becomes a low-temperature, low-pressure liquid, and then enters through the e interface of the reversing three-way valve 103, and flows out from the g interface to enter the first heat exchanger 104. At this time, the refrigerant is lower than the outside temperature, evaporates and absorbs heat, and becomes a low-temperature, low-pressure gas. At this time, the first heat exchanger 104 is an evaporator, and then flows out of the first heat exchanger 104, enters through the b interface of the reversing four-way valve 102, flows out from the c interface, and finally enters the compressor 101 to continue the cycle. As the refrigerant is running, the lubricating oil will not only adhere to the second heat exchanger 105 with the flow of the refrigerant, but also after the evaporation operation is completed in the first heat exchanger 104, most of the lubricating oil is still in liquid due to the low temperature, which will cause a large amount of lubricating oil to separate from the refrigerant, resulting in the accumulation of lubricating oil in the first heat exchanger 104.

[0042] When the four-pipe heat pump system is in heat recovery mode, the high-temperature and high-pressure refrigerant gas compressed by the compressor 101 carries the lubricating oil and flows out from the outlet of the compressor 101, enters through the a interface of the reversing four-way valve 102, and flows out from the d interface into the second heat exchanger 105. At this time, low-temperature liquid is introduced into the second heat exchanger 105. Since the refrigerant is in a high-temperature and high-pressure state at this time, the refrigerant condenses and releases heat in the second heat exchanger 105, becomes a low-temperature and high-pressure liquid, and heats the liquid in the second heat exchanger 105. , then flows out from the second heat exchanger 105, enters the expansion valve 107, throttles and reduces the pressure of the refrigerant, and the refrigerant becomes a low-temperature, low-pressure liquid. Then it enters through the e interface of the reversing three-way valve 103, and flows out from the f interface to enter the third heat exchanger 106. At this time, the third heat exchanger 106 is filled with high-temperature liquid, and the refrigerant evaporates and absorbs heat to cool the liquid in the third heat exchanger 106, and the refrigerant becomes a low-temperature, low-pressure gas. Then the low-temperature, low-pressure refrigerant flows back to the compressor 101 and continues to circulate. As the operation progresses, the lubricating oil will not only adhere to the second heat exchanger 105 with the flow of the refrigerant, but also after the evaporation operation is completed in the third heat exchanger 106, most of the lubricating oil is still in liquid state due to the low temperature, which will cause a large amount of lubricating oil to separate from the refrigerant, resulting in the accumulation of lubricating oil in the third heat exchanger 106.

[0043] With long-term operation, the lubricating oil accumulated in the first heat exchanger 104, the second heat exchanger 105 and the third heat exchanger 106 gradually increases, and the lubricating oil in the compressor 101 gradually decreases. When the liquid level switch 201 detects that the liquid level of the lubricating oil is too low, the return oil solenoid valve 202 is connected, thereby connecting the return oil passage, and starting to replenish oil to the compressor 101.

[0044] When the oil return passage is connected and the four-pipe heat pump system is in cooling mode, the refrigerant flowing out from the f interface of the reversing three-way valve 103 will be divided into two paths. One path will flow into the third heat exchanger 106 normally in cooling mode, and the other part will enter the second heat exchanger 105 through the oil return solenoid valve 202. At this time, the second heat exchanger 105 does not work and only serves as a channel for the circulation of refrigerant, so that the refrigerant drives the lubricating oil accumulated in the second heat exchanger 105 to flow back to the compressor 101, thereby replenishing the oil of the compressor 101 in cooling mode and avoiding damage to the compressor 101 due to lack of lubricating oil.

[0045] When the oil return passage is connected and the four-pipe heat pump system is in heating mode, the refrigerant flowing out from the g interface of the reversing three-way valve 103 will be divided into two paths. One path will flow into the first heat exchanger 104 normally in heating mode, and the other part will enter the third heat exchanger 106 through the oil return solenoid valve 202. At this time, the third heat exchanger 106 does not work, but only serves as a channel for the circulation of refrigerant, so that the refrigerant drives the lubricating oil accumulated in the third heat exchanger 106 to flow back to the compressor 101, thereby replenishing the oil of the compressor 101 in heating mode and avoiding damage to the compressor 101 due to lack of lubricating oil.

[0046] When the oil return passage is connected and the four-pipe heat pump system is in heat recovery mode, the refrigerant flowing out from the f interface of the reversing three-way valve 103 will be divided into two paths. One path will flow into the third heat exchanger 106 normally in heat recovery mode, and the other part will enter the first heat exchanger 104 through the oil return solenoid valve 202. At this time, the first heat exchanger 104 does not work and only serves as a channel for the circulation of refrigerant, so that the refrigerant drives the lubricating oil accumulated in the first heat exchanger 104 to flow back to the compressor 101, thereby realizing oil replenishment for the compressor 101 in heat recovery mode and avoiding damage to the compressor 101 due to lack of lubricating oil.

[0047] Alternatively, if Figure 1As shown, the heat exchange unit further includes a cooling container 108, a first one-way valve 109 and an angle valve 110. The cooling container 108 stores a coolant for heat exchange with the refrigerant in the compressor 101. One end of the cooling container 108 is connected to the first heat exchanger 104, and the other end is connected to the inlet of the first one-way valve 109. The angle valve 110 is used to connect the outlet of the first one-way valve 109 with the inlet of the expansion valve 107. By providing the cooling container 108 with coolant stored therein, the refrigerant flowing out of the first heat exchanger 104 is further cooled in the cooling mode, thereby improving the heat exchange efficiency of the refrigerant in the third heat exchanger 106.

[0048] Alternatively, if Figure 1 As shown, the heat exchange unit further includes a liquid reservoir 111 and a second one-way valve 112, the second heat exchanger 105 includes a gas circuit interface and a liquid circuit outlet, the gas circuit interface is communicated with the reversing four-way valve 102, the liquid circuit outlet is communicated with the liquid reservoir 111, the liquid reservoir 111 is communicated with the inlet of the second one-way valve 112, and the outlet of the second one-way valve 112 is communicated with the angle valve 110. By providing the liquid reservoir 111, the excess liquid in the refrigerant after condensation from the second heat exchanger 105 is stored, thereby avoiding liquid hammer and damage to the compressor 101.

[0049] Alternatively, if Figure 1 As shown, the second heat exchanger 105 further includes a liquid circuit inlet, and the heat exchange unit further includes a third one-way valve 113, the outlet of the third one-way valve 113 is connected to the liquid circuit inlet, and the inlet of the third one-way valve 113 is connected to the reversing three-way valve 103. By setting the third one-way valve 113, the flow route of the refrigerant is guaranteed to avoid backflow.

[0050] Alternatively, if Figure 1 As shown, the heat exchange unit further includes a fourth one-way valve 114, the inlet of the fourth one-way valve 114 is connected in parallel with the inlet of the third one-way valve 113 at the outlet of the reversing three-way valve 103, and the outlet of the fourth one-way valve 114 is connected to the first heat exchanger 104. By setting the fourth one-way valve 114, the flow route of the refrigerant is guaranteed to avoid backflow.

[0051] Alternatively, if Figure 1 As shown, the heat exchange unit further includes a filter dryer 115, which is disposed between the angle valve 110 and the inlet of the expansion valve 107. By providing the filter dryer 115, the refrigerant entering the expansion valve 107 is dried and filtered, and the expansion valve 107 is protected.

[0052] Optionally, the first heat exchanger 104 is a fin heat exchanger. By using a fin heat exchanger as the first heat exchanger 104, the contact area between the first heat exchanger 104 and the outside air is increased, thereby improving the heat exchange efficiency. In this embodiment, the second heat exchanger 105 and the third heat exchanger 106 are both shell and tube heat exchangers. The shell and tube heat exchanger has a simple structure and reliable operation. It is one of the most widely used types. Its design enables it to handle a large number of heat transfer tasks, and it is relatively easy to maintain and clean. It mainly uses the wall surface of the tube bundle as a heat transfer surface to achieve heat exchange between two fluids of different temperatures through inter-wall heat transfer. In this embodiment, the second heat exchanger 105 can use heat exchange with the refrigerant to achieve the heating function of the liquid, and the third heat exchanger 106 can use heat exchange with the refrigerant to achieve the cooling function of the liquid.

[0053] Optionally, the second heat exchanger 105 further includes a first medium inlet and a first medium outlet, wherein the first medium inlet is used to introduce the liquid to be heated into the second heat exchanger 105, and the first medium outlet is used to output the liquid to be heated. By providing the first medium inlet and the first medium outlet, the liquid to be heated can flow in the second heat exchanger 105.

[0054] Optionally, the third heat exchanger 106 further includes a second medium inlet and a second medium outlet, wherein the second medium inlet is used to introduce the liquid to be cooled into the third heat exchanger 106, and the second medium outlet is used to output the liquid to be cooled. By providing the second medium inlet and the second medium outlet, the liquid to be cooled can flow in the third heat exchanger 106.

[0055] This embodiment also provides an air conditioner, which includes the above-mentioned four-pipe heat pump system. By applying the above-mentioned four-pipe heat pump system, the air conditioner not only reduces the cost, but also avoids the compressor 101 from being damaged due to lack of lubricating oil due to long-term use, thereby indirectly increasing the service life of the air conditioner and reducing the maintenance cost.

[0056] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of protection of the present invention. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A four-pipe heat pump system, characterized in that: The four-pipe heat pump system comprises: A heat exchange unit, the heat exchange unit comprising a compressor (101), a reversing four-way valve (102), a reversing three-way valve (103), a first heat exchanger (104), a second heat exchanger (105), a third heat exchanger (106) and an expansion valve (107), the reversing four-way valve (102) being capable of selectively connecting an inlet or an outlet of the compressor (101) to the first heat exchanger (104) or the second heat exchanger (105), the inlet of the expansion valve (107) being connected to the first heat exchanger (104) or the second heat exchanger (105), one end of the reversing three-way valve (103) being connected to the outlet of the expansion valve (107), and the other end being connected to the inlet of the first heat exchanger (104) or the third heat exchanger (106), the outlet of the third heat exchanger (106) being connected to the inlet of the compressor (101); An oil return unit, the oil return unit comprising a liquid level switch (201) and an oil return solenoid valve (202); one end of the oil return solenoid valve (202) is connected to a pipeline between the reversing three-way valve (103) and the first heat exchanger (104), and the other end is connected to a pipeline between the reversing three-way valve (103) and the third heat exchanger (106); the liquid level switch (201) is arranged in the compressor (101) and is used to detect the liquid level of the oil in the compressor (101) so as to control the on and off of the oil return solenoid valve (202).

2. The four-pipe heat pump system according to claim 1, characterized in that: The heat exchange unit also includes a cooling container (108), a first one-way valve (109) and an angle valve (110). The cooling container (108) stores a cooling liquid for heat exchange with the refrigerant in the compressor (101). One end of the cooling container (108) is connected to the first heat exchanger (104), and the other end is connected to the inlet of the first one-way valve (109). The angle valve (110) is used to connect the outlet of the first one-way valve (109) with the inlet of the expansion valve (107).

3. The four-pipe heat pump system according to claim 2, characterized in that: The heat exchange unit further comprises a liquid reservoir (111) and a second one-way valve (112); the second heat exchanger (105) comprises an air circuit interface and a liquid circuit outlet; the air circuit interface is connected to the reversing four-way valve (102); the liquid circuit outlet is connected to the liquid reservoir (111); the liquid reservoir (111) is connected to the inlet of the second one-way valve (112); and the outlet of the second one-way valve (112) is connected to the angle valve (110).

4. The four-pipe heat pump system according to claim 3, characterized in that: The second heat exchanger (105) further includes a liquid circuit inlet, and the heat exchange unit further includes a third one-way valve (113), the outlet of the third one-way valve (113) is connected to the liquid circuit inlet, and the inlet of the third one-way valve (113) is connected to the reversing three-way valve (103).

5. The four-pipe heat pump system according to claim 4, characterized in that: The heat exchange unit further comprises a fourth one-way valve (114), an inlet of the fourth one-way valve (114) and an inlet of the third one-way valve (113) being connected in parallel at the outlet of the reversing three-way valve (103), and an outlet of the fourth one-way valve (114) being connected to the first heat exchanger (104).

6. The four-pipe heat pump system according to claim 2, characterized in that: The heat exchange unit further comprises a drying filter (115), wherein the drying filter (115) is arranged between the angle valve (110) and the inlet of the expansion valve (107).

7. The four-pipe heat pump system according to claim 1, characterized in that: The first heat exchanger (104) is a fin heat exchanger.

8. The four-pipe heat pump system according to claim 1, characterized in that: The second heat exchanger (105) further comprises a first medium inlet and a first medium outlet, wherein the first medium inlet is used to introduce the liquid to be heated into the second heat exchanger (105), and the first medium outlet is used to output the liquid to be heated.

9. The four-pipe heat pump system according to claim 1, characterized in that: The third heat exchanger (106) further comprises a second medium inlet and a second medium outlet, wherein the second medium inlet is used to introduce the liquid to be cooled into the third heat exchanger (106), and the second medium outlet is used to output the liquid to be cooled.

10. An air conditioner, characterized in that The air conditioner comprises a four-pipe heat pump system as claimed in any one of claims 1 to 9.

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