Compressor oil return system and control method thereof, and heat pump system

Abstract

The application relates to a compressor oil return system and a control method thereof and a heat pump system. The compressor oil return system comprises a controller, a compressor and an oil separator. A first pipeline is arranged between an exhaust port of the compressor and an oil inlet of the oil separator. A second pipeline is arranged between an air inlet of the compressor and an oil outlet of the oil separator. An oil return capillary tube is arranged on the second pipeline. A third pipeline is arranged between an inlet of the oil return capillary tube and the second pipeline. A bypass control valve is arranged on the third pipeline. The compressor oil return system comprises an ambient temperature detection device configured to detect an ambient temperature of an environment where the compressor oil return system is located. The controller is configured to control the bypass control valve to be in an open state when the compressor is in a heating mode, and the ambient temperature is less than or equal to a first temperature threshold. The compressor can be ensured to normally return oil, and the working reliability of the unit is improved.

Description

Technical Field

[0001] The present application relates to the technical field of compressor oil return systems, and in particular to a compressor oil return system and a control method thereof, and a heat pump system. Background Art

[0002] As people's living standards continue to improve, they have increasingly higher requirements for their living environment. In order to maintain a comfortable ambient temperature, heat pump units have become an indispensable device in people's lives. Generally, a heat pump unit includes an indoor unit, an outdoor unit, and a circulation loop for connecting the indoor and outdoor units. The refrigerant in the heat pump unit continuously exchanges heat between the outdoor and indoor units through the circulation loop, thereby achieving the effect of changing the room temperature. At the same time, the refrigerant requires the assistance of a compressor during the gas-liquid change process, and some existing compressors must use lubricating oil in the process of compressing the refrigerant to ensure stable operation. These lubricating oils will enter the refrigerant circulation pipeline along with the refrigerant.

[0003] In the prior art, existing heat pump units typically install an oil separator downstream of the compressor to separate the lubricating oil from the refrigerant in order to return the lubricating oil to the compressor. The oil in the oil separator is then reintroduced into the compressor via an oil return capillary to ensure normal operation. However, at lower ambient temperatures, the compressor's lubricating oil temperature is low and the viscosity of the lubricating oil is high, making it difficult to ensure fluidity. This can lead to oil shortages and slow oil return, resulting in insufficient lubrication of the compressor and affecting the unit's operational reliability. Summary of the Invention

[0004] The present application provides a compressor oil return system and its control method, as well as a heat pump system, to solve the technical problem that in existing heat pump units, the lubricating oil temperature of the compressor is low and the viscosity of the lubricating oil is high under low ambient temperatures, and the fluidity of the lubricating oil cannot be guaranteed. As a result, there will be oil shortages, slow oil return, and other phenomena, resulting in insufficient lubrication of the compressor and affecting the operating reliability of the unit.

[0005] In a first aspect, the present application provides a compressor oil return system, the compressor oil return system comprising a controller, a compressor, and an oil separator, a first pipeline being provided between an exhaust port of the compressor and an oil inlet of the oil separator, a second pipeline being provided between an air inlet of the compressor and an oil outlet of the oil separator, an oil return capillary being provided on the second pipeline, a third pipeline being provided between an inlet of the oil return capillary and the second pipeline, and a bypass control valve being provided on the third pipeline;

[0006] The compressor oil return system includes an ambient temperature detection device, which is configured to detect the ambient temperature of an environment in which the compressor oil return system is located;

[0007] The controller is electrically connected with the bypass control valve, and the controller is electrically connected with the ambient temperature detection device, and the controller is configured to, in a state that the compressor is in the heating mode and the ambient temperature is less than or equal to the first temperature threshold, control the bypass control valve to be in an open state.

[0008] In a possible implementation, in a state that the compressor is in the heating mode and the ambient temperature is less than or equal to the first temperature threshold, the controller is configured to control the opening degree of the bypass control valve based on the magnitude of the ambient temperature.

[0009] In a possible implementation, the compressor oil return system comprises a first temperature detection device configured to detect the oil return temperature of the oil outlet of the oil separator.

[0010] The controller is electrically connected with the first temperature detection device, and the controller is configured to, in a state that the current opening duration of the bypass control valve is greater than or equal to the first preset duration and the oil return temperature is greater than the target oil return temperature, control the bypass control valve to be in a closed state.

[0011] In a possible implementation, the compressor oil return system comprises a second temperature detection device configured to detect the exhaust temperature of the compressor.

[0012] The controller is electrically connected with the second temperature detection device, and the controller is configured to, in a state that the ambient temperature is less than or equal to the first temperature threshold, control the opening degree of the bypass control valve based on the magnitude of the exhaust temperature.

[0013] In a possible implementation, the controller is configured to, in a state that the compressor is in a closed state, control the bypass control valve to be in a closed state.

[0014] In a second aspect, the present application provides a heat pump system, the heat pump system comprising the compressor oil return system as described above.

[0015] In a possible implementation, the heat pump system comprises a first heat exchanger, and a refrigerant inlet of the first heat exchanger is connected with a refrigerant outlet of the oil separator of the compressor oil return system through a fourth pipeline.

[0016] The compressor oil return system comprises an ambient temperature detection device, and the ambient temperature detection device is arranged on the first heat exchanger.

[0017] In a possible implementation, the heat pump system comprises a second heat exchanger, a refrigerant inlet of the second heat exchanger is connected with a refrigerant outlet of the first heat exchanger, a refrigerant outlet of the second heat exchanger is connected with an air inlet of the compressor through a fifth pipeline, and a four-way valve is arranged on the fourth pipeline and the fifth pipeline.

[0018] The flow path of the four-way valve is controllably connected between the compressor, the first heat exchanger and the second heat exchanger, so as to realize switching of the compressor between the refrigeration mode and the heating mode.

[0019] In a third aspect, the application provides a control method of a compressor oil return system, applied to the compressor oil return system as described above, and the control method comprises:

[0020] obtaining an operating mode of the compressor and an ambient temperature of an environment in which the compressor oil return system is located;

[0021] In a state where the ambient temperature is less than or equal to a first temperature threshold, if the compressor is in the heating mode, the bypass control valve is controlled to be in an open state.

[0022] In a possible implementation, the control method comprises:

[0023] In the state where the ambient temperature is less than or equal to the first temperature threshold, the opening degree of the bypass control valve is controlled based on the size of the ambient temperature.

[0024] In a possible implementation, the control method comprises:

[0025] If the outdoor ambient temperature is greater than a second temperature threshold and less than or equal to the first temperature threshold, the bypass control valve is controlled to be opened at a first opening degree, wherein the second temperature threshold is less than the first temperature threshold;

[0026] If the outdoor ambient temperature is greater than a third temperature threshold and less than or equal to the second temperature threshold, the bypass control valve is controlled to be opened at a second opening degree, wherein the third temperature threshold is less than the second temperature threshold, and the second opening degree is greater than the first opening degree;

[0027] If the outdoor ambient temperature is less than or equal to the third temperature threshold, the bypass control valve is controlled to be fully opened.

[0028] In a possible implementation, the compressor oil return system comprises a first temperature detection device, and the control method comprises:

[0029] obtaining an opening duration of the bypass control valve and an oil return temperature of the oil return capillary;

[0030] In a state where the current opening duration of the bypass control valve is greater than or equal to a first preset duration and the oil return temperature is greater than a target oil return temperature, the bypass control valve is controlled to be in a closed state.

[0031] In a possible implementation, the compressor oil return system comprises a second temperature detection device, and the control method comprises:

[0032] obtaining an exhaust temperature of the compressor;

[0033] In a state where the ambient temperature is less than or equal to a first temperature threshold, the opening degree of the bypass control valve is controlled based on the magnitude of the exhaust temperature.

[0034] In a possible implementation, controlling the opening degree of the bypass control valve based on the magnitude of the exhaust temperature comprises:

[0035] If the exhaust temperature of the compressor is greater than a fourth temperature threshold and less than or equal to a fifth temperature threshold, the bypass control valve is controlled to open at a first opening degree, wherein the fourth temperature threshold is less than the fifth temperature threshold.

[0036] If the exhaust temperature of the compressor is greater than the fifth temperature threshold and less than or equal to a sixth temperature threshold, the bypass control valve is controlled to open at a second opening degree, wherein the fifth temperature threshold is less than the sixth temperature threshold.

[0037] If the exhaust temperature of the compressor is greater than the sixth temperature threshold, the bypass control valve is controlled to be fully open.

[0038] In a possible implementation, the method comprises:

[0039] Obtaining the working state of the compressor;

[0040] In a state where the compressor is in the closed state, the bypass control valve is controlled to be in the closed state.

[0041] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0042] The compressor oil return system and the control method thereof and the heat pump system provided by the embodiment of the present application, in the working process of the compressor, the lubricating oil used in the compressor will flow out from the exhaust port together with the refrigerant, and then flow into the oil separator through the oil inlet of the oil separator after passing through the first pipeline. After the separation of the oil separator, the refrigerant is discharged through the exhaust port arranged above the oil separator, and the lubricating oil is discharged through the oil outlet arranged below the oil separator. The lubricating oil discharged through the oil outlet below the oil separator can flow back to the suction port side of the compressor through the second pipeline, and then flow into the lubricating system of the compressor again through the pipeline, so as to be used in the working process of the compressor. The controller can obtain the operating condition of the compressor. When the compressor oil return system is in the heating mode, if the ambient temperature is less than or equal to the first temperature threshold, it indicates that the environment of the compressor oil return system at this time is relatively harsh, and the low temperature leads to that the viscosity of the lubricating oil is relatively large and the flowability is relatively poor. At this time, the bypass control valve is in the open state, the exhaust temperature of the compressor exhaust port side is relatively high, a part of the refrigerant and the high-temperature mixture of the lubricating oil flowing out from the compressor exhaust port are introduced into the second pipeline from the third pipeline, the high-temperature mixture can heat the lubricating oil in the oil return capillary, so as to improve the flowability of the lubricating oil, and the lubricating oil deposited in the lower part of the oil separator can quickly return to the compressor through the second pipeline under the action of the pressure difference, so as to ensure that the compressor can normally return oil, ensure that the compressor has enough lubricating oil, and then improve the working reliability of the unit and prolong the service life of the compressor. BRIEF DESCRIPTION OF DRAWINGS

[0043] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate an embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without any creative labor.

[0045] One or more embodiments are exemplarily illustrated by the pictures in the drawings corresponding thereto, and these exemplary illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, unless otherwise specified. The drawings in the drawings do not constitute a proportional limitation.

[0046] Figure 1 A structural schematic diagram of a compressor oil return system provided by the embodiment of the present application;

[0047] Figure 2 A structural schematic diagram of a heat pump system provided by the embodiment of the present application;

[0048] Figure 3 For Figure 2 Fig. 1 is a schematic diagram showing the working principle of a heat pump system, wherein the hollow arrow shows the refrigerant flow direction in cooling mode, and the solid arrow shows the refrigerant flow direction in heating mode;

[0049] Figure 4 Fig. 4 is a flow chart of a control method of a compressor oil return system according to an embodiment of the present application;

[0050] Figure 5 Fig. 5 is a flow chart of a control method of a compressor oil return system according to another embodiment of the present application.

[0051] Explanation of reference numerals:

[0052] 100, heat pump system;

[0053] 1, compressor; 2, oil separator; 3, oil return capillary; 4, bypass control valve; 5, ambient temperature detection device; 6, oil filter; 7, first temperature detection device; 8, second temperature detection device; 9, first heat exchanger; 10, second heat exchanger; 11, four-way valve; 12, throttling element; 13, gas-liquid separator;

[0054] G1, first pipeline; G2, second pipeline; G3, third pipeline; G4, fourth pipeline; G5, fifth pipeline; G6, sixth pipeline. DETAILED DESCRIPTION

[0055] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0056] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplification, the components and arrangements of the specific examples are described in the following. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to the numerals and / or letters in different examples. Such repetition is for the purpose of simplification and clarity, and it does not indicate the relationship between the various embodiments and / or arrangements discussed.

[0057] For the convenience of description, spatial relative terms can be used in the specification to describe the relative position relationship or movement condition of one element or feature with respect to another element or feature as shown in the drawings, such as "inner", "outer", "inboard", "outboard", "under", "below", "on", "above", "front", "back", and the like. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawings is turned over or reversed, or the orientation of the device changes or the movement state changes, the directional indications also change accordingly, for example: the element described as "under" or "below" another element or feature will be subsequently oriented as "above" or "above" another element or feature. Therefore, the example term "below" can include both upward and downward positions. The device can be additionally oriented (rotated by 90 degrees or in other directions), and the spatial relative relationship descriptors used in the specification are interpreted accordingly.

[0058] In the prior art, in order to send the lubricating oil back to the compressor, the existing heat pump unit usually separates the lubricating oil in the refrigerant by arranging an oil separator downstream of the compressor, and then the lubricating oil in the oil separator is introduced into the compressor through the oil return capillary to ensure the normal operation of the compressor. However, at a lower ambient temperature, the lubricating oil of the compressor has a lower oil temperature and a larger viscosity, and the flowability of the lubricating oil cannot be guaranteed, so that oil deficiency, slow oil return and other phenomena occur, which leads to insufficient lubrication of the compressor and affects the operation reliability of the unit.

[0059] In order to solve the technical problem that the existing heat pump unit has insufficient lubrication of the compressor at a lower ambient temperature, the lubricating oil of the compressor has a lower oil temperature and a larger viscosity, and the flowability of the lubricating oil cannot be guaranteed, so that oil deficiency, slow oil return and other phenomena occur, which leads to insufficient lubrication of the compressor and affects the operation reliability of the unit, the present application provides a compressor oil return system and a control method thereof, and a heat pump system. A part of the refrigerant and the high-temperature mixture of the lubricating oil flowing out of the compressor exhaust port can be used to heat the lubricating oil in the oil return capillary, thereby improving the flowability of the lubricating oil, so that the lubricating oil deposited in the lower part of the oil separator can quickly return to the compressor through the second pipeline under the action of the pressure difference, ensuring that the compressor can normally return oil, ensuring that the compressor has sufficient lubricating oil, thereby improving the working reliability of the unit and prolonging the service life of the compressor.

[0060] As Figure 1As shown, the present application provides a compressor oil return system, which comprises a controller, a compressor 1 and an oil separator 2, a first pipeline G1 is arranged between the exhaust port of the compressor 1 and the oil inlet of the oil separator 2, a second pipeline G2 is arranged between the air inlet of the compressor 1 and the oil outlet of the oil separator 2, an oil return capillary tube 3 is arranged on the second pipeline G2, a third pipeline G3 is arranged between the inlet of the oil return capillary tube 3 and the second pipeline G2, and a bypass control valve 4 is arranged on the third pipeline G3.

[0061] The compressor oil return system comprises an ambient temperature detection device 5, which is configured to detect the ambient temperature of the environment where the compressor oil return system is located.

[0062] The controller is electrically connected with the bypass control valve 4 and electrically connected with the ambient temperature detection device 5, and the controller is configured to, when the compressor 1 is in a heating mode, if the ambient temperature is less than or equal to a first temperature threshold, control the bypass control valve 4 to be in an open state.

[0063] In the working process of the compressor 1, the lubricating oil used in the compressor 1 will flow out from the exhaust port together with the refrigerant, and after passing through the first pipeline, it will flow into the oil separator 2 through the oil inlet of the oil separator 2. After the separation action of the oil separator 2, the refrigerant is discharged through the exhaust port arranged above the oil separator 2, and the lubricating oil is discharged through the oil outlet arranged below the oil separator 2. The lubricating oil discharged through the oil outlet below the oil separator 2 can flow back to the air inlet side of the compressor 1 through the second pipeline, and then flow into the lubricating system of the compressor 1 again through the pipeline for use in the working process of the compressor 1. The controller can obtain the operating condition of the compressor 1. When the compressor oil return system is in a heating mode, if the ambient temperature is less than or equal to a first temperature threshold, it indicates that the environment where the compressor oil return system is located is relatively harsh at this time, and the low temperature causes the viscosity of the lubricating oil to be relatively large and the flowability to be relatively poor. At this time, the bypass control valve 4 is controlled to be in an open state, the exhaust temperature of the compressor 1 is relatively high, a part of the high-temperature mixture of the refrigerant and the lubricating oil flowing out from the exhaust port of the compressor 1 is introduced into the second pipeline from the third pipeline, and the high-temperature mixture can heat the lubricating oil in the oil return capillary tube 3, thereby improving the flowability of the lubricating oil, so that the lubricating oil deposited in the lower part of the oil separator 2 can quickly return to the compressor 1 through the second pipeline G2 under the action of the pressure difference, ensuring that the compressor 1 can normally return oil, ensuring that the compressor 1 has enough lubricating oil, thereby improving the working reliability of the unit and prolonging the service life of the compressor 1.

[0064] It should be noted that the present application does not make any limitation on the specific structure and type of the compressor 1 and the oil separator 2, as long as the compressor 1 needs to use lubricating oil in the working process and the oil separator 2 can separate the refrigerant and the lubricating oil.

[0065] The ambient temperature of the environment where the compressor oil return system is located can refer to the ambient temperature of the compressor 1 side, the ambient temperature of the oil return capillary tube 3 side, or the ambient temperature of the oil separator 2 side. Generally, the oil return capillary tube 3, the compressor 1, the oil separator 2, and part of the pipeline are generally placed outdoors, and the ambient temperature here can also be the outdoor ambient temperature. Alternatively, the first temperature threshold can be set to -15°C. After consulting a large number of lubricating oil characteristics, -15°C is the dividing point of the viscosity of lubricating oil, so the first temperature threshold is set to -15°C for judgment in the embodiment of the application. Of course, if the viscosity dividing point of a certain lubricating oil is other temperatures, the first temperature threshold can also be set to other values.

[0066] It should be emphasized that the bypass control valve 4 in the open state includes complete conduction and various degrees of conduction, which is not limited in the embodiment. The bypass electromagnetic valve can use existing electromagnetic valves, proportional valves, and other control valves, which can adjust the opening size according to the control parameters. The specific structure and working principle can refer to the prior art, which will not be repeated here.

[0067] In some embodiments, an oil filter 6 can be provided between the oil outlet of the oil separator 2 and the inlet of the oil return capillary tube 3. The impurities mixed in the lubricating oil can be filtered through the oil filter 6, and the pollution degree of the oil entering the system can be reduced to avoid the blockage of the lubricating system of the compressor 1 caused by impurities. Similarly, the specific structure and type of the oil filter 6 are not limited in the application. The rated pressure, filtering accuracy, filter size (actual flow), pollution capacity, filter replacement pressure difference, and the like of the oil filter 6 can be selected according to the type of the compressor 1, air flow, working pressure, and the like.

[0068] In some embodiments, when the compressor 1 is in the heating mode, the controller is configured to control the opening of the bypass control valve 4 based on the size of the ambient temperature when the ambient temperature is less than or equal to the first temperature threshold.

[0069] It can be understood that the size of the ambient temperature indicates the severity of the environment in which the compressor oil return system is located at this time. The lower the ambient temperature, the greater the viscosity of the lubricating oil, the poorer the flowability, and therefore the controllable bypass control valve 4 can be adjusted to increase the opening degree to introduce more high-temperature mixture from the third pipeline into the second pipeline to accelerate the warming of the oil return capillary 3 and improve the flowability of the lubricating oil, so that the lubricating oil deposited in the lower part of the oil separator 2 can quickly return to the compressor 1 through the second pipeline G2 under the action of the pressure difference, ensuring that the compressor 1 can normally return oil and that the compressor 1 has enough lubricating oil, thereby improving the working reliability of the unit and prolonging the service life of the compressor 1. The higher the ambient temperature, the smaller the viscosity of the lubricating oil, and the better the flowability, so the controllable bypass control valve 4 can be adjusted to reduce the opening degree to prevent too much refrigerant or lubricating oil from flowing into the compressor 1 through the second pipeline from the third pipeline, preventing the compressor 1 from being damaged due to liquid hammer.

[0070] If the bypass control valve 4 is in the open state for a long time, too much refrigerant will flow out of the compressor 1 into the third pipeline G3, causing the heating capacity of the heat pump system 100 to decay too much, affecting the heating capacity delivered by the heat pump system 100 to the room, and resulting in poor user comfort. Therefore, the application also monitors the opening duration of the bypass control valve 4 and the oil return temperature, and controls the closing state of the bypass control valve 4 based on the opening duration of the bypass control valve 4 and the oil return temperature.

[0071] In some embodiments, the compressor oil return system comprises a first temperature detection device 7 configured to detect the oil return temperature of the oil outlet of the oil separator 2; the controller is electrically connected with the first temperature detection device 7, and the controller is configured to control the bypass control valve 4 to be in a closed state when the current opening duration t of the bypass control valve 4 is greater than or equal to a first preset duration tm and the oil return temperature is greater than a target oil return temperature.

[0072] It should be noted that the first temperature detection device 7 can be provided on the second pipeline G2, and the first temperature detection device 7 is located between the oil outlet of the oil separator 2 and the inlet of the oil return capillary 3. The current opening duration of the bypass control valve 4 refers to the duration from the current opening to the complete closing of the bypass control valve 4, and the current opening state of the bypass control valve 4 includes the completely open state and different degrees of open state. The target oil return temperature T0 can be set to 0℃, because the compressor 1 in the heating mode, the unit is easy to frost in the environment below 0℃ for a long time, the temperature in the finned tube corresponding to the frosting position will be lower than the ambient temperature, at this time the viscosity of the refrigeration oil is high, easy to condense and adhere to the inner wall of the pipeline, causing abnormal oil return of the unit, causing damage to the compressor 1 and the unit shutdown, and unable to guarantee the user comfort.

[0073] It can be understood that, in the current time length of the bypass control valve 4 is greater than or equal to the first preset time length, and the oil return temperature is greater than the target oil return temperature, which indicates that the oil return temperature is higher than the critical temperature of frosting, at this time, under the pressure difference of the oil return capillary 3, the lubricating oil below the oil separator 2 can flow into the compressor 1 through the second pipeline G2 quickly, therefore, it is not necessary to additionally heat the oil return capillary 3, and the bypass control valve 4 is controlled to be in the closed state, so as to reduce the energy consumption of the system, which can ensure the normal oil return of the compressor 1, and also avoid that the heat output of the unit is attenuated too much to affect the normal heating, thereby ensuring the comfort of the user.

[0074] Optionally, tm is set to 5 min, and the bypass control valve 4 is set to be opened for at least the first preset time length, so that the compressor 1 can always be supplied with lubricating oil within the first preset time length, which can prevent the lubricating oil from being absent in a short time after starting to cause the wear of the compressor 1. The bypass control valve 4 is opened for at least 5 min, which is obtained through experimental verification, and the opening time length of the bypass electromagnetic valve is within 5 min, so that the heat output of the unit can be ensured, and the heat output will not be attenuated.

[0075] Of course, the present embodiment can also be combined with the foregoing embodiments to obtain more embodiments, which are exemplarily illustrated below according to actual situations.

[0076] In one example, the ambient temperature is -16℃, and the compressor 1 is in the opened state, the bypass electromagnetic valve is controlled to be in the opened state, and a part of the high-temperature mixture of the refrigerant and the lubricating oil flowing out of the exhaust port of the compressor 1 flows into the second pipeline from the third pipeline, the high-temperature mixture can heat the lubricating oil in the oil return capillary 3, thereby improving the flowability of the lubricating oil, so that the lubricating oil deposited in the lower part of the oil separator 2 can quickly return to the compressor 1 through the second pipeline G2 under the pressure difference; the current time length of the bypass electromagnetic valve reaches 6 min, and the oil return temperature is 5℃, at this time, it is not necessary to additionally heat the oil return capillary 3, and the bypass control valve 4 is controlled to be in the closed state.

[0077] In one example, the ambient temperature is -16℃, and the compressor 1 is in the opened state, the bypass electromagnetic valve is controlled to be in the opened state, and a part of the high-temperature mixture of the refrigerant and the lubricating oil flowing out of the exhaust port of the compressor 1 flows into the second pipeline from the third pipeline, the high-temperature mixture can heat the lubricating oil in the oil return capillary 3, thereby improving the flowability of the lubricating oil, so that the lubricating oil deposited in the lower part of the oil separator 2 can quickly return to the compressor 1 through the second pipeline G2 under the pressure difference; the current time length of the bypass electromagnetic valve reaches 6 min, and the oil return temperature is -2℃, at this time, it is still necessary to heat the oil return capillary 3 by using the exhaust temperature, and the bypass electromagnetic valve is still controlled to be in the opened state; then, after 4 min, the opening time length of the bypass electromagnetic valve reaches 10 min, and the oil return temperature is 1℃, at this time, it is not necessary to additionally heat the oil return capillary 3, and the bypass control valve 4 is controlled to be in the closed state.

[0078] In some embodiments, the compressor oil return system comprises a second temperature detection device 8 configured to detect the exhaust temperature of the compressor 1; the controller is electrically connected with the second temperature detection device 8, and the controller is configured to control the opening degree of the bypass control valve 4 based on the magnitude of the exhaust temperature in a state where the ambient temperature is less than or equal to the first temperature threshold.

[0079] It can be understood that the magnitude of the exhaust temperature can represent the speed of temperature rise of the high-temperature mixture on the exhaust port side of the compressor 1 for heating the oil return capillary 3. The higher the exhaust temperature, the faster the temperature rise of the oil return capillary 3 under the same flow rate and time, and the faster the oil return temperature can reach the target oil return temperature. Therefore, based on the magnitude of the exhaust temperature, the opening degree of the bypass control valve 4 can be controlled to be adjusted to be increased. If the exhaust temperature of the compressor 1 is low, the bypass control valve 4 can be controlled to introduce more high-temperature mixture from the third pipeline into the second pipeline to accelerate the temperature rise of the oil return capillary 3, improve the flowability of the lubricating oil, and enable the lubricating oil deposited in the lower part of the oil separator 2 to quickly return to the compressor 1 under the action of the pressure difference, so as to ensure that the compressor 1 can normally return oil, ensure that the compressor 1 has sufficient lubricating oil, and thus improve the working reliability of the unit and prolong the service life of the compressor 1. If the exhaust temperature of the compressor 1 is higher, the opening degree of the bypass control valve 4 can be reduced to avoid too much refrigerant or lubricating oil from flowing into the compressor 1 from the third pipeline through the second pipeline, prevent the compressor 1 from being subjected to liquid impact and thus being worn, and at the same time avoid too much heat attenuation, thereby saving system energy consumption.

[0080] In some embodiments, the controller is configured to control the bypass control valve 4 to be in a closed state when the compressor 1 is in a closed state.

[0081] If the compressor 1 is in a closed state, the compressor 1 has no oil return requirement at this time, and the bypass control valve 4 is in a closed state at this time. It needs to be understood that the foregoing embodiment controls the bypass control valve 4 to be in an open state on the premise that the compressor 1 is in an open state.

[0082] The embodiment of the present application provides a heat pump system 100, which comprises the compressor oil return system as described above. The compressor oil return system comprises a controller, a compressor 1, an oil separator 2, first and second pipelines G2, and a third pipeline G3, wherein the second pipeline G2 is provided with an oil return capillary 3, and the third pipeline G3 is provided with a bypass control valve 4.

[0083] In the working process of the compressor 1, the lubricating oil used in the compressor 1 will flow out from the exhaust port together with the refrigerant, and after passing through the first pipeline, it will flow into the oil separator 2 through the oil inlet of the oil separator 2. After the separation of the oil separator 2, the refrigerant is discharged through the exhaust port arranged above the oil separator 2, and the lubricating oil is discharged through the oil outlet arranged below the oil separator 2. The lubricating oil discharged through the oil outlet below the oil separator 2 can flow back to the suction port side of the compressor 1 through the second pipeline, and then flow into the lubricating system of the compressor 1 again through the pipeline, so as to be used in the working process of the compressor 1. The controller can obtain the operating condition of the compressor 1. When the compressor oil return system is in the heating mode, if the ambient temperature is less than or equal to the first temperature threshold, it indicates that the environment where the compressor oil return system is located is relatively harsh at this time, and the low temperature causes the viscosity of the lubricating oil to be relatively large and the flowability to be relatively poor. At this time, the bypass control valve 4 is in the open state, the exhaust temperature of the compressor 1 is relatively high, a part of the high-temperature mixture of the refrigerant and the lubricating oil flowing out of the exhaust port of the compressor 1 is introduced into the second pipeline from the third pipeline, and the high-temperature mixture can heat the lubricating oil in the oil return capillary tube 3, thereby improving the flowability of the lubricating oil, so that the lubricating oil deposited in the lower part of the oil separator 2 can quickly return to the compressor 1 through the second pipeline G2 under the action of the pressure difference, and the compressor 1 can be ensured to normally return oil, the compressor 1 can be ensured to have enough lubricating oil, and the working reliability of the unit is improved, thereby prolonging the service life of the compressor 1.

[0084] Further, the heat pump system 100 comprises a first heat exchanger 9, and a fourth pipeline G4 is connected between the refrigerant inlet of the first heat exchanger 9 and the refrigerant outlet of the oil separator 2 of the compressor oil return system; the compressor oil return system comprises an ambient temperature detection device 5, and the ambient temperature detection device 5 is arranged on the first heat exchanger 9.

[0085] The first heat exchanger 9 is usually arranged outdoors, and the ambient temperature detection device 5 is arranged on the first heat exchanger 9. At this time, the ambient temperature detection device 5 is configured to detect the outdoor ambient temperature. When the compressor oil return system is in the heating mode, if the outdoor ambient temperature is less than or equal to the first temperature threshold, it indicates that the environment where the compressor oil return system is located is relatively harsh at this time, and the low temperature causes the viscosity of the lubricating oil to be relatively large and the flowability to be relatively poor. At this time, the bypass control valve 4 is in the open state, the exhaust temperature of the compressor 1 is relatively high, a part of the high-temperature mixture of the refrigerant and the lubricating oil flowing out of the exhaust port of the compressor 1 is introduced into the second pipeline from the third pipeline, and the high-temperature mixture can heat the lubricating oil in the oil return capillary tube 3, thereby improving the flowability of the lubricating oil, so that the lubricating oil deposited in the lower part of the oil separator 2 can quickly return to the compressor 1 through the second pipeline G2 under the action of the pressure difference, and the compressor 1 can be ensured to normally return oil, the compressor 1 can be ensured to have enough lubricating oil, and the working reliability of the unit is improved, thereby prolonging the service life of the compressor 1.

[0086] Optionally, the first heat exchanger 9 may adopt an existing fin heat exchanger. The specific structure and working principle of the fin heat exchanger can refer to the existing technology and will not be described in detail here.

[0087] Furthermore, if Figure 2 As shown, the heat pump system 100 also includes a second heat exchanger 10, and the refrigerant inlet of the second heat exchanger 10 is connected to the refrigerant outlet of the first heat exchanger 9 through a sixth pipeline G6. A throttling element 12 is provided on the sixth pipeline G6. The throttling element 12 can adopt a throttling device such as an electronic expansion valve or a capillary tube. The refrigerant outlet of the second heat exchanger 10 is connected to the air inlet of the compressor 1 through a fifth pipeline G5, and a four-way valve 11 is provided on the fourth pipeline G4 and the fifth pipeline G5; the flow path of the four-way valve 11 is controllably switched and connected between the compressor 1, the first heat exchanger 9 and the second heat exchanger 10 to realize the switching of the compressor 1 between the cooling mode and the heating mode.

[0088] Optionally, the second heat exchanger 10 may adopt an existing plate heat exchanger. The specific structure and working principle of the plate heat exchanger can refer to the existing technology and will not be described in detail here.

[0089] Specifically, if Figure 3 As shown, in cooling mode, the compressor 1 draws in low-pressure refrigerant vapor from the second heat exchanger 10 (equivalent to the evaporator in this case), increases its pressure, and then feeds it into the first heat exchanger 9 (equivalent to the condenser in cooling mode). In the first heat exchanger 9, it condenses into a higher-pressure liquid. This part of the refrigerant liquid is throttled by the throttling element 12 and becomes a lower-pressure liquid. After that, it is fed into the second heat exchanger 10 (equivalent to the evaporator in cooling mode), where it absorbs heat and evaporates into a lower-pressure vapor. It is then fed into the air inlet of the compressor 1, thus completing the refrigeration cycle. The four-way valve 11 switches its internal flow path. In heating mode, the compressor 1 draws in low-temperature, low-pressure gas from the first heat exchanger 9 (equivalent to the evaporator in heating mode), compresses it, and increases its pressure into a high-temperature, high-pressure liquid. The high-temperature, high-pressure liquid enters the second heat exchanger 10 (equivalent to the condenser in heating mode). In the second heat exchanger 10, the high-temperature, high-pressure refrigerant releases heat with the external medium and liquefies into a medium-temperature, high-pressure liquid. It is then fed into the air inlet of the compressor 1, thus completing the heating cycle.

[0090] Optionally, a gas-liquid separator 13 is further provided on the fifth pipeline G5. In the cooling mode, the gas-liquid separator 13 can prevent the liquid refrigerant from entering the compressor 1 and causing liquid hammer in the compressor 1.

[0091] like Figure 4 As shown, an embodiment of the present application further provides a control method for a compressor oil return system, which is applied to the compressor oil return system as described above. The control method includes the following steps:

[0092] S1. Obtain the operating mode of the compressor 1 and the ambient temperature of the environment where the compressor oil return system is located; the operating modes of the compressor 1 include heating mode and cooling mode. Generally, when the compressor 1 is in heating mode, the ambient temperature is low, resulting in high viscosity and poor fluidity of the lubricating oil, which is not conducive to the lubricating oil in the oil separator 2 being reintroduced into the compressor 1 using the oil return capillary 3.

[0093] S2. When the compressor 1 is in the heating mode, if the ambient temperature Ts is less than or equal to the first temperature threshold, the bypass control valve 4 is controlled to be in an open state.

[0094] When the compressor oil return system is in heating mode, if the ambient temperature is less than or equal to the first temperature threshold, it indicates that the environment of the compressor oil return system is relatively harsh, and the low temperature causes the viscosity of the lubricating oil to be larger and the fluidity to be poor. Then, at this time, the bypass control valve 4 is controlled to be in the open state, and the exhaust temperature on the exhaust port side of the compressor 1 is higher. A part of the high-temperature mixture of refrigerant and lubricating oil flowing out of the exhaust port of the compressor 1 is introduced into the second pipe from the third pipe. The high-temperature mixture can heat the lubricating oil in the oil return capillary 3, thereby improving the fluidity of the lubricating oil, so that the lubricating oil deposited in the lower part of the oil separator 2 can quickly return to the compressor 1 through the second pipe G2 under the action of the pressure difference, ensuring that the compressor 1 can return oil normally and ensuring that the compressor 1 has sufficient lubricating oil, thereby improving the working reliability of the unit and extending the service life of the compressor 1.

[0095] In some embodiments, the control method further comprises the following steps:

[0096] When the ambient temperature is less than or equal to the first temperature threshold, the opening degree of the bypass control valve 4 is controlled based on the magnitude of the ambient temperature.

[0097] The lower the ambient temperature, the greater the viscosity of the lubricating oil and the worse its fluidity. Therefore, the bypass control valve 4 can be controlled to adjust its opening to increase, introducing more high-temperature mixture flowing out of the exhaust port of the compressor 1 from the third pipe into the second pipe, accelerating the temperature rise of the oil return capillary 3, and improving the fluidity of the lubricating oil. The lubricating oil deposited in the lower part of the oil separator 2 can quickly return to the compressor 1 through the second pipe G2 under the action of the pressure difference, ensuring that the compressor 1 can return oil normally and that the compressor 1 has sufficient lubricating oil, thereby improving the operating reliability of the unit and extending the service life of the compressor 1. The higher the ambient temperature, the lower the viscosity of the lubricating oil and the relatively better its fluidity. Therefore, the bypass control valve 4 can be controlled to adjust its opening to decrease, preventing excessive refrigerant or lubricating oil liquid from flowing from the third pipe through the second pipe into the compressor 1, preventing liquid hammer in the compressor 1 and causing wear of the compressor 1.

[0098] Controlling the opening of the bypass control valve 4 based on the ambient temperature specifically includes the following steps:

[0099] If the outdoor ambient temperature is greater than the second temperature threshold and less than or equal to the first temperature threshold, the bypass control valve 4 is controlled to open to a first opening degree, wherein the second temperature threshold is less than the first temperature threshold.

[0100] If the outdoor ambient temperature is greater than the third temperature threshold and less than or equal to the second temperature threshold, the bypass control valve 4 is controlled to open to a second opening, wherein the third temperature threshold is less than the second temperature threshold and the second opening is greater than the first opening.

[0101] If the outdoor ambient temperature is less than or equal to the third temperature threshold, the bypass control valve 4 is controlled to be fully opened.

[0102] In one example, the first temperature threshold is set to -15°C, the second temperature threshold is set to -20°C, and the third temperature threshold is set to -25°C. The first opening of the bypass solenoid valve is 1 / 3 of the valve body's full opening, and the second opening of the bypass solenoid valve is 2 / 3 of the valve body's full opening. If -20°C < Ts ≤ -15°C, the bypass control valve 4 is controlled to open to the first opening; if -25°C < Ts ≤ -20°C, the bypass control valve 4 is controlled to open to the second opening; if Ts ≤ -25°C, the bypass control valve 4 is controlled to fully open.

[0103] In some embodiments, as Figure 5 As shown, the compressor oil return system includes a first temperature detection device 7, and the control method includes the following steps:

[0104] S3, obtaining the opening time of the bypass control valve 4 and the return oil temperature of the oil return capillary 3;

[0105] S4. When the current opening time of the bypass control valve 4 is greater than or equal to the first preset time and the return oil temperature is greater than the target return oil temperature, the bypass control valve 4 is controlled to be in a closed state.

[0106] It can be understood that when the current opening time of the bypass control valve 4 is greater than or equal to the first preset time, and the return oil temperature is greater than the target return oil temperature, it indicates that the return oil temperature is higher than the critical temperature of frost. At this time, under the pressure difference of the return oil capillary 3, the lubricating oil below the oil separator 2 can quickly flow into the compressor 1 through the second pipeline G2. Therefore, there is no need to additionally heat the return oil capillary 3. The bypass control valve 4 is controlled to be in a closed state to reduce the energy consumption of the system. Through the above control strategy, the normal oil return of the compressor 1 can be guaranteed, and the heating capacity of the unit can be avoided from being excessively attenuated to affect normal heating, thereby ensuring user comfort.

[0107] In some embodiments, the compressor oil return system includes a second temperature detection device 8, and the control method further includes:

[0108] acquiring an exhaust temperature Tp of the compressor 1;

[0109] In a state where the ambient temperature Ts is less than or equal to the first temperature threshold, the opening degree of the bypass control valve 4 is controlled based on the magnitude of the exhaust temperature.

[0110] The higher the exhaust temperature, the faster the temperature of the oil return capillary 3 rises under the same time and flow, and the faster the oil return temperature reaches the target oil return temperature. Therefore, the opening degree of the bypass control valve 4 can be controlled to increase based on the magnitude of the exhaust temperature. If the exhaust temperature of the compressor 1 is low, the bypass control valve 4 can be controlled to introduce more high-temperature mixture from the third pipeline into the second pipeline, accelerate the temperature rise of the oil return capillary 3, improve the flowability of the lubricating oil, and enable the lubricating oil deposited in the lower part of the oil separator 2 to quickly return to the compressor 1 under the action of the pressure difference, so as to ensure that the compressor 1 can normally return oil, ensure that the compressor 1 has sufficient lubricating oil, and thus improve the working reliability of the unit and prolong the service life of the compressor 1. If the exhaust temperature of the compressor 1 is higher, the opening degree of the bypass control valve 4 can be controlled to decrease, so as to avoid too much refrigerant or lubricating oil from flowing into the compressor 1 from the third pipeline through the second pipeline, prevent the compressor 1 from being subjected to liquid impact and thus causing wear of the compressor 1, and simultaneously avoid excessive reduction of the heating capacity, thereby saving system energy consumption.

[0111] Therefore, the opening degree of the bypass control valve 4 can be controlled based on the magnitude of the exhaust temperature or the magnitude of the ambient temperature.

[0112] Controlling the opening degree of the bypass control valve 4 based on the magnitude of the exhaust temperature specifically includes the following steps: if the exhaust temperature of the compressor 1 is greater than a fourth temperature threshold and less than or equal to a fifth temperature threshold, the bypass control valve 4 is controlled to be fully opened, wherein the fourth temperature threshold is less than the fifth temperature threshold.

[0113] If the exhaust temperature of the compressor 1 is greater than the fifth temperature threshold and less than or equal to a sixth temperature threshold, the bypass control valve 4 is controlled to be opened by a second opening degree, wherein the fifth temperature threshold is less than the sixth temperature threshold.

[0114] If the exhaust temperature of the compressor 1 is greater than the sixth temperature threshold, the bypass control valve 4 is controlled to be opened by a first opening degree, wherein the first opening degree is less than the second opening degree.

[0115] In one example, the fourth temperature threshold is set at 80°C, the fifth temperature threshold is set at 90°C, and the sixth temperature threshold is set at 100°C. The first opening of the bypass solenoid valve is 1 / 3 of the valve body's full opening, and the second opening of the bypass solenoid valve is 2 / 3 of the valve body's full opening. If 80<Tp≤90°C, the bypass control valve 4 is controlled to be fully open; if 90°C<Tp≤-100°C, the bypass control valve 4 is controlled to be opened to the second opening; if Ts>100°C, the bypass control valve 4 is controlled to be opened to the first opening.

[0116] The control method further includes the following steps:

[0117] The working state of the compressor 1 is obtained; when the compressor 1 is in the off state, the bypass control valve 4 is controlled to be in the off state.

[0118] If the compressor 1 is in the off state, there is no oil return demand for the compressor 1, and the bypass control valve 4 is controlled to be in the closed state. It should be understood that the premise of the above-mentioned control of the bypass control valve 4 in the open state is that the compressor 1 is in the open state.

[0119] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0120] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0121] The foregoing is considered as illustrative only of the principles of the application. Numerous modifications and changes will readily occur to those skilled in the art, and it is intended to embrace all such modifications and changes that fall within the scope of the application. Accordingly, the application is not to be restricted in scope to the specific embodiments disclosed herein but is to be accorded the full scope that the principles and novel features request appropriately granted.

Claims

1. A compressor oil return system, characterized in that: The compressor oil return system includes a controller, a compressor, and an oil separator. A first pipeline is provided between the exhaust port of the compressor and the oil inlet of the oil separator. A second pipeline is provided between the air inlet of the compressor and the oil outlet of the oil separator. An oil return capillary is provided on the second pipeline. A third pipeline is provided between the inlet of the oil return capillary and the second pipeline. A bypass control valve is provided on the third pipeline. The compressor oil return system includes an ambient temperature detection device, wherein the ambient temperature detection device is configured to detect the ambient temperature of the environment in which the compressor oil return system is located; The controller is electrically connected to the bypass control valve and the ambient temperature detection device, and is configured to control the bypass control valve to be in an open state if the ambient temperature is less than or equal to a first temperature threshold when the compressor is in a heating mode; When the compressor is in heating mode, the controller is configured to control the opening of the bypass control valve based on the ambient temperature when the ambient temperature is less than or equal to the first temperature threshold; The controller is configured to control the bypass control valve to be in a closed state when the compressor is in an off state.

2. The compressor oil return system according to claim 1, characterized in that: The compressor oil return system includes a first temperature detection device, which is configured to detect the return oil temperature of the oil outlet of the oil separator; The controller is electrically connected to the first temperature detection device, and is configured to control the bypass control valve to be in a closed state when the current opening time of the bypass control valve is greater than or equal to a first preset time and the return oil temperature is greater than a target return oil temperature.

3. The compressor oil return system according to claim 1, characterized in that: The compressor oil return system includes a second temperature detection device, wherein the second temperature detection device is configured to detect the exhaust temperature of the compressor; The controller is electrically connected to the second temperature detection device. The controller is configured to control the opening of the bypass control valve based on the exhaust temperature when the ambient temperature is less than or equal to a first temperature threshold.

4. A heat pump system, characterized in that: The heat pump system includes the compressor oil return system according to any one of claims 1 to 3.

5. The heat pump system according to claim 4, characterized in that: The heat pump system includes a first heat exchanger, wherein a refrigerant inlet of the first heat exchanger is connected to a refrigerant outlet of the oil separator of the compressor oil return system via a fourth pipeline; The compressor oil return system includes an ambient temperature detection device, which is arranged on the first heat exchanger.

6. The heat pump system according to claim 5, characterized in that: The heat pump system includes a second heat exchanger, wherein a refrigerant inlet of the second heat exchanger is connected to a refrigerant outlet of the first heat exchanger, and the refrigerant outlet of the second heat exchanger is connected to an air inlet of the compressor via a fifth pipeline, and a four-way valve is provided on the fourth pipeline and the fifth pipeline; The flow path of the four-way valve is controllably switchably connected between the compressor, the first heat exchanger, and the second heat exchanger to achieve switching of the compressor between a cooling mode and a heating mode.

7. A method for controlling a compressor oil return system, applied to the compressor oil return system according to any one of claims 1 to 3, characterized in that: The control method includes: Obtaining an operating mode of the compressor and an ambient temperature of an environment where an oil return system of the compressor is located; When the compressor is in a heating mode, if the ambient temperature is less than or equal to a first temperature threshold, the bypass control valve is controlled to be in an open state.

8. The control method according to claim 7, characterized in that: include: When the ambient temperature is less than or equal to the first temperature threshold, the opening of the bypass control valve is controlled based on the magnitude of the ambient temperature.

9. The control method according to claim 8, characterized in that: The controlling of the opening of the bypass control valve based on the ambient temperature includes: If the ambient temperature is greater than a second temperature threshold and less than or equal to the first temperature threshold, controlling the bypass control valve to open to a first opening, wherein the second temperature threshold is less than the first temperature threshold; If the ambient temperature is greater than a third temperature threshold and less than or equal to the second temperature threshold, controlling the bypass control valve to open to a second opening, wherein the third temperature threshold is less than the second temperature threshold, and the second opening is greater than the first opening; If the ambient temperature is less than or equal to the third temperature threshold, the bypass control valve is controlled to be fully opened.

10. The control method according to claim 7, characterized in that: The compressor oil return system includes a first temperature detection device, and the control method includes: Obtaining the opening time of the bypass control valve and the return oil temperature of the oil return capillary; When the current opening time of the bypass control valve is greater than or equal to a first preset time and the return oil temperature is greater than a target return oil temperature, the bypass control valve is controlled to be in a closed state.

11. The control method according to claim 7, characterized in that: The compressor oil return system includes a second temperature detection device, and the control method includes: Get the exhaust temperature of the compressor; When the ambient temperature is less than or equal to a first temperature threshold, the opening of the bypass control valve is controlled based on the exhaust temperature.

12. The control method according to claim 11, characterized in that: The controlling of the opening of the bypass control valve based on the exhaust temperature includes: If the exhaust temperature of the compressor is greater than a fourth temperature threshold and less than or equal to a fifth temperature threshold, controlling the bypass control valve to be fully opened, wherein the fourth temperature threshold is less than the fifth temperature threshold; If the exhaust temperature of the compressor is greater than the fifth temperature threshold and less than or equal to a sixth temperature threshold, controlling the bypass control valve to open to a second opening degree, wherein the fifth temperature threshold is less than the sixth temperature threshold; If the exhaust temperature of the compressor is greater than the sixth temperature threshold, the bypass control valve is controlled to open to a first opening degree, wherein the first opening degree is smaller than the second opening degree.

13. The control method according to claim 7, characterized in that: include: Obtaining the operating status of the compressor; When the compressor is in an off state, the bypass control valve is controlled to be in a closed state.

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