Refrigeration system

Abstract

A refrigeration system is provided with: a refrigerant circuit in which a refrigerant circulates through a compressor, a condenser capable of exchanging heat with air or water, a throttle element, a filter element, and an evaporator in this order; the refrigerant branch is used for enabling a refrigerant to enter the evaporator through the compressor, the regulating valve and the filter element in sequence; a temperature detection section configured to detect a refrigerant temperature between the throttling element and the filter element; outputting an intervention trigger signal when the detection value is below a first predetermined value, and stopping outputting the intervention trigger signal when the detection value is above the first predetermined value; the control part is configured to execute intervention control when the temperature detection part outputs the intervention trigger signal; the control valve is controlled to conduct the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under the condition that the time interval between outputting the intervention trigger signal and stopping outputting the intervention trigger signal is larger than the time interval between outputting the intervention trigger signal and stopping outputting the intervention trigger signal; wherein the first preset value is higher than the pour point of the refrigerating machine oil. Oil blockage can be prevented.

Description

Technical Field

[0001] The invention relates to the technical field of air conditioning, and in particular to a refrigeration system. Background Art

[0002] As the global greenhouse effect becomes increasingly serious, the air-conditioning field has higher and higher requirements for the environmental protection of refrigerants. R290 is an environmentally friendly and efficient refrigerant with good refrigeration performance. It can provide efficient cooling effects without damaging the ozone layer in the atmosphere or causing global warming. R290 is propane, a natural gas, and its GWP (Global Warming Potential) is usually defined as 0, which means that compared with the same mass of carbon dioxide, the greenhouse gas effect of R290 is very low. However, R290 is a flammable refrigerant. For safety reasons, the amount of R290 refrigerant charged is strictly limited.

[0003] In refrigeration systems, refrigeration oil is usually mixed in the refrigerant to lubricate and cool the moving parts of the compressor. This is very important to keep the compressor running smoothly, as they cycle between high and low pressures and work at high temperatures and high pressures. The flow of refrigerant will carry the refrigeration oil into the expansion valve, and due to the sudden drop in pressure, a portion of the liquid refrigerant will quickly evaporate into a gaseous state. This process is called "flash." Flashing will cause the temperature of the refrigerant to drop sharply, quickly dropping to a very low level; if this temperature is lower than the pour point of the refrigeration oil (the lower limit of the temperature of the refrigeration oil), then the refrigeration oil may solidify into a solid or very viscous state. Lubricating mechanisms that solidify or become very viscous in the expansion valve and filter will clog these components, causing abnormal operation, performance degradation or failure of the refrigeration system.

[0004] Therefore, for example, the following method is proposed in patent document 1 (CN114992899A): "An openable and closable bypass pipeline, whose first end is connected to the connecting pipeline between the four-way valve and the indoor heat exchanger, and whose second end is connected to the connecting pipeline between the indoor heat exchanger and the throttling element; the control unit is used to respond to the heating instruction, control the refrigerant circulation loop to transport the refrigerant in the heating refrigerant flow direction, and periodically control the opening of the bypass pipeline for a preset time until the bypass pipeline is opened a preset number of times." The bypassed high-temperature and high-pressure gaseous refrigerant is mixed with the condensed liquid refrigerant and then throttled by the expansion valve. However, due to the properties of the mixed gas and the different working conditions of the expansion valve, flash may still occur, causing the temperature to be lower than the pour point of the refrigeration oil, especially if the mixing ratio or composition of the liquid refrigerant and the high-temperature and high-pressure gaseous refrigerant is not appropriate, which may cause the mixed gas to flash. Under certain mixing ratios, the flash of the gaseous component may cause a sharp drop in temperature, and if the opening of the expansion valve cannot adapt to the conditions of the mixed gas, it may not be possible to effectively control the throttling of the mixed gas, thus causing flash, and the above-mentioned problems cannot be solved. Summary of the invention

[0005] In order to solve the problem that the bypassed high-temperature and high-pressure gaseous refrigerant is mixed with the condensed liquid refrigerant and then throttled by the expansion valve, a "flash" phenomenon may still occur due to the properties of the mixed gas and the different working conditions of the expansion valve, resulting in the temperature being lower than the pour point of the refrigeration oil and the anti-oil blockage protection failing. The first aspect of the present application designs and provides a refrigeration system.

[0006] A refrigeration system, comprising: a refrigerant circuit, wherein a refrigerant circulates sequentially through a compressor, a condenser, a throttling element, a filter element and an evaporator, wherein the condenser exchanges heat with air;

[0007] In one or more embodiments of the present application, the refrigeration system further comprises: a refrigerant branch, which supplies refrigerant to the evaporator in sequence via a compressor, a regulating valve, and a filter element; a temperature detection unit, which is configured to detect the refrigerant temperature between the throttling element and the filter element; output an intervention trigger signal when the detection value is below a first predetermined value, and stop outputting the intervention trigger signal when the detection value is above the first predetermined value; and a control unit, which is configured to perform intervention control when the temperature detection unit outputs the intervention trigger signal: control the regulating valve to open the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the output of the intervention trigger signal; wherein the first predetermined value is higher than the pour point of the refrigeration oil.

[0008] In one or more embodiments of the present application, the temperature detection unit is also configured to perform intervention control in the control unit, and output a release trigger signal when the detection value is above a second predetermined value that is higher than the first predetermined value; the control unit is configured to perform recovery control when the temperature detection unit outputs the release trigger signal: controlling the regulating valve to close the refrigerant branch to maintain the temperature of the refrigerant flowing into the filter element.

[0009] In one or more embodiments of the present application, the difference between the first predetermined value and the pour point of the refrigeration oil is smaller than the difference between the second predetermined value and the first predetermined value.

[0010] In one or more embodiments of the present application, the control unit is further configured to: first control the outdoor heat exchanger located in the outdoor unit to operate as an evaporator, and the indoor heat exchanger located in the indoor unit to operate as a condenser; then control the outdoor heat exchanger located in the outdoor unit to operate as a condenser, and the indoor heat exchanger located in the indoor unit to operate as an evaporator to melt the surface frost layer of the outdoor heat exchanger; then control the outdoor heat exchanger located in the outdoor unit to operate as an evaporator, and the indoor heat exchanger located in the indoor unit to operate as a condenser, and at the same time, perform intervention control when the temperature detection unit outputs the intervention trigger signal: control the regulating valve to open the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the output of the intervention trigger signal.

[0011] In one or more embodiments of the present application, the temperature detection unit is also configured to perform intervention control in the control unit, and output a protection trigger signal when the detection value is below a third predetermined value that is lower than the first predetermined value; the control unit is configured to control the compressor to stop running while performing the intervention control.

[0012] In one or more embodiments of the present application, the third predetermined value is not lower than the pour point of the refrigeration oil.

[0013] In one or more embodiments of the present application, a pressure reducing element is further provided on the refrigerant branch, which allows the refrigerant to enter the evaporator via the compressor, the regulating valve, the pressure reducing element, and the filter element in sequence.

[0014] The second aspect of the present application provides a refrigeration system, which is an air source heat pump and has: a refrigerant circuit, in which the refrigerant circulates sequentially through a compressor, a condenser, a throttling element, a filter element and an evaporator, and the condenser performs heat exchange with water.

[0015] In one or more embodiments of the present application, the refrigeration system further comprises: a refrigerant branch, which supplies refrigerant to the evaporator in sequence via a compressor, a regulating valve, and a filter element; a temperature detection unit, which is configured to detect the refrigerant temperature between the throttling element and the filter element; output an intervention trigger signal when the detection value is below a first predetermined value, and stop outputting the intervention trigger signal when the detection value is above the first predetermined value; and a control unit, which is configured to perform intervention control when the temperature detection unit outputs the intervention trigger signal: control the regulating valve to open the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the output of the intervention trigger signal; wherein the first predetermined value is higher than the pour point of the refrigeration oil.

[0016] In one or more embodiments of the present application, the temperature detection unit is also configured to perform intervention control in the control unit, and output a release trigger signal when the detection value is above a second predetermined value that is higher than the first predetermined value; the control unit is configured to perform recovery control when the temperature detection unit outputs the release trigger signal: controlling the regulating valve to close the refrigerant branch to maintain the temperature of the refrigerant flowing into the filter element.

[0017] In one or more embodiments of the present application, the difference between the first predetermined value and the pour point of the refrigeration oil is smaller than the difference between the second predetermined value and the first predetermined value.

[0018] In one or more embodiments of the present application, the control unit is further configured to: first control the outdoor heat exchanger located in the outdoor unit to operate as an evaporator, and the indoor heat exchanger located in the indoor unit to operate as a condenser; then control the outdoor heat exchanger located in the outdoor unit to operate as a condenser, and the indoor heat exchanger located in the indoor unit to operate as an evaporator to melt the surface frost layer of the outdoor heat exchanger; then control the outdoor heat exchanger located in the outdoor unit to operate as an evaporator, and the indoor heat exchanger located in the indoor unit to operate as a condenser, and at the same time, perform intervention control when the temperature detection unit outputs the intervention trigger signal: control the regulating valve to open the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the output of the intervention trigger signal.

[0019] In one or more embodiments of the present application, the temperature detection unit is also configured to perform intervention control in the control unit, and output a protection trigger signal when the detection value is below a third predetermined value that is lower than the first predetermined value; the control unit is configured to control the compressor to stop running while performing the intervention control.

[0020] In one or more embodiments of the present application, the third predetermined value is not lower than the pour point of the refrigeration oil.

[0021] In one or more embodiments of the present application, a pressure reducing element is further provided on the refrigerant branch, which allows the refrigerant to enter the evaporator via the compressor, the regulating valve, the pressure reducing element, and the filter element in sequence.

[0022] Through the cooperation of the temperature detection unit and the control unit, the high-temperature and high-pressure gaseous refrigerant is guided to between the throttling element and the filter element, thereby increasing the temperature of the refrigerant and avoiding a sudden drop in the temperature of the refrigeration oil near the throttling element, thereby reducing the risk of condensation and decreased fluidity of the refrigeration oil; the prior art adopts open-loop control for the "flash" phenomenon, which cannot ensure the properties of the mixed gas, that is, it cannot ensure that the intervention control to prevent oil blockage is effective. Introducing high-temperature and high-pressure gaseous refrigerant downstream of the throttling element can reduce the possibility of condensate formation inside the throttling element, avoid causing blockage or failure of the throttling element, and affect the performance of the system. In addition, in the heating mode, this means that when the intervention control is performed, the refrigerant temperature in the evaporator will be slightly higher than that of the conventional control. The higher evaporation temperature helps to prevent frost or frost on the evaporator surface, thereby reducing the frequency of defrosting, improving the efficiency of the evaporator, and reducing energy loss. Controlling the conduction of the regulating valve under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the output of the intervention trigger signal can ensure that the refrigerant temperature is higher than the pour point temperature of the refrigeration oil and has a certain distance from it. At the same time, it can also avoid the original blockage of the pipeline causing uneven flow of refrigerant in the system, causing uneven temperature distribution, resulting in partial overcooling and further aggravating the blockage.

[0023] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A schematic diagram of the structure of a refrigeration system proposed in one or more embodiments of the present application;

[0026] Figure 2 A schematic diagram of the structure of a refrigeration system proposed in one or more embodiments of the present application;

[0027] Figure 3A schematic diagram of the structure of a refrigeration system proposed in one or more embodiments of the present application;

[0028] Figure 4 A schematic diagram of the structure of a refrigeration system proposed in one or more embodiments of the present application;

[0029] Figure 5 A schematic diagram of the structure of a refrigeration system proposed in one or more embodiments of the present application;

[0030] Figure 6 A schematic diagram of the structure of a refrigeration system proposed in one or more embodiments of the present application;

[0031] Figure 7 A schematic diagram of the structure of a refrigeration system proposed in one or more embodiments of the present application;

[0032] Figure 8 A timing diagram of a refrigeration system proposed in one or more embodiments of the present application;

[0033] Fig. 9 A timing diagram of a refrigeration system proposed in one or more embodiments of the present application;

[0034] Fig.10 A flow chart of a refrigeration system proposed for one or more embodiments of the present application;

[0035] Fig.11 A schematic diagram of the structure of a refrigeration system proposed in one or more embodiments of the present application;

[0036] Fig.12 A flow chart of a refrigeration system proposed for one or more embodiments of the present application;

[0037] Fig.13 A flow chart of a refrigeration system proposed for one or more embodiments of the present application;

[0038] Fig.14 A flow chart of a refrigeration system proposed for one or more embodiments of the present application;

[0039] Fig.15 A flow chart of a refrigeration system proposed for one or more embodiments of the present application;

[0040] Fig.16 An example of a data table corresponding to a first adjustment coefficient and a temperature difference in a refrigeration system proposed in one or more embodiments of the present application;

[0041] In the figure, 1, refrigeration system; 100, compressor; 102, outdoor unit; 104, indoor unit; 106, outdoor heat exchanger; 108, outdoor fan; 110, reversing valve; 112, throttling element; 114, indoor heat exchanger; 116, indoor fan; 118, indoor heat exchanger; 120, water inlet pipe; 122, water outlet pipe; 124, filter element; 126, refrigerant branch; 128, regulating valve; 130, first filter element; 132, second filter element; 134, temperature sensor; 136, pressure reducing element; 200, temperature detection unit; 300, control unit. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0044] The terms "first", "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0045] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] In the present invention, unless otherwise clearly stipulated 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 means 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 means that the first feature is lower in level than the second feature.

[0047] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0048] Figure 1 A schematic diagram showing the structure of a refrigeration system 1 provided in one or more embodiments of the present invention; Figure 2 An example of a refrigerant circuit formed by the refrigeration system 1 according to the embodiment of the present invention (operating in a heating mode) is shown.

[0049] The refrigeration system 1 shown in the figure is installed in buildings such as apartments, hotels, office buildings, and residences. The refrigeration system 1 can independently perform cooling operation or independently perform heating operation.

[0050] A refrigeration cycle is integrated in the refrigeration system 1. The refrigeration cycle is mainly implemented by a refrigerant circuit, in which a compressor 100, a condenser, a throttling element 112 and an evaporator are used. The refrigeration cycle includes a series of processes involving compression, condensation, expansion and evaporation to cool or heat the indoor space.

[0051] From a principle perspective, low-temperature, low-pressure refrigerant enters the compressor 100, which compresses it into high-temperature, high-pressure refrigerant gas and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0052] The throttling element 112 expands the high-temperature and high-pressure liquid refrigerant condensed in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the refrigerant expanded in the throttling device and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor 100. The evaporator can achieve a refrigeration effect by utilizing the latent heat of evaporation of the refrigerant to exchange heat with the material to be cooled. In the whole cycle, the refrigeration system 1 can adjust the temperature of the indoor space.

[0053] The refrigeration system 1 includes an outdoor unit 102 and an indoor unit 104 connected to each other. Figure 1 and Figure 2 Only one outdoor unit 102 and one indoor unit 104 are shown in the figure, but in the present application, there is no particular limitation on the number of outdoor units 102 and indoor units 104. Only one outdoor unit 102 or only one indoor unit 104 can be arranged in one refrigeration system 1 in the same manner as the indoor unit 104 and the outdoor unit 102 as shown in the figure.

[0054] The indoor unit 104 and the outdoor unit 102 are connected by a liquid-side communication pipe and a gas-side communication pipe. The liquid-side communication pipe and the gas-side communication pipe are used to allow the refrigerant to flow so that the refrigerant can form a refrigerant circuit and circulate therein.

[0055] In one or more embodiments of the present application, a liquid-side shutoff valve (not shown) may be provided on the liquid-side connecting pipe, and a gas-side shutoff valve (not shown) may be provided on the gas-side connecting pipe. The liquid-side shutoff valve may shut off the fluid passage in the liquid-side connecting pipe or, when the opening is minimum, may be close to shutting off the fluid passage in the liquid-side connecting pipe, and the gas-side shutoff valve may shut off the fluid passage in the gas-side connecting pipe or, when the opening is minimum, may be close to shutting off the fluid passage in the gas-side connecting pipe.

[0056] In one or more embodiments of the present application, the refrigerant flowing in the refrigeration system 1 is R290 refrigerant.

[0057] The following describes the basic structure and functions of the outdoor unit 102. When the same system architecture is used, the number of outdoor units 102 can be expanded to multiple and run in groups.

[0058] In one or more embodiments of the present application, the outdoor unit 102 of the refrigeration system 1 refers to a part of the refrigeration cycle including the compressor 100 and the outdoor heat exchanger 106. The outdoor unit 102 can perform heating operation or cooling operation on the outdoor side to provide energy for increasing the indoor temperature or reducing the indoor temperature to the indoor unit 104. The outdoor unit 102 is also provided with a gas-liquid separator (not shown), an outdoor fan 108 and a reversing valve 110 (such as a four-way valve); the outdoor unit 102 may also be provided with a liquid storage tank (not shown).

[0059] like Figure 2 As shown, in the heating operation, the outdoor unit 102 can form a refrigerant circuit for heating operation (hereinafter referred to as a heating cycle), wherein the throttling element 112, the outdoor heat exchanger 106, the reversing valve 110 (for example, the passage between the C port and the S port of the four-way valve), the gas-liquid separator, the compressor 100 and the reversing valve 110 (for example, the passage between the D port and the E port) are sequentially connected from the liquid side connecting pipe to the gas side connecting pipe, as shown in FIG. Figure 2 Indicated by the arrow.

[0060] Under refrigeration operation, the outdoor unit 102 can form a refrigerant circuit for refrigeration operation (hereinafter referred to as a refrigeration cycle), in which the reversing valve 110 (for example, the passage between the E port and the S port of the four-way valve), the gas-liquid separator, the compressor 100, the four-way valve (for example, the passage between the D port and the C port), the outdoor heat exchanger 106 and the throttling element 112 are connected in sequence from the gas-side connecting piping to the liquid-side connecting piping.

[0061] In the present application, the throttling element 112 may be implemented by an electronic expansion valve.

[0062] The compressor 100 is configured to suck in and compress the refrigerant into a high-temperature and high-pressure state. The type of the compressor 100 is not further limited herein, and may be, for example, a reciprocating compressor 100, a screw compressor 100, etc. The speed of the compressor 100 is variably controlled by a frequency converter. The number of compressors 100 may be one or more.

[0063] The outdoor heat exchanger 106 is configured to be used as a condenser in cooling operation and as an evaporator in heating operation. The outdoor heat exchanger 106 can perform heat exchange with the air guided by the outdoor fan 108 so that the refrigerant flowing in the outdoor heat exchanger 106 undergoes a phase change (condensation or evaporation). The speed of the outdoor fan 108 can be controlled to change the flow rate of the air heat exchanged with the outdoor heat exchanger 106 by adjusting the speed. The outdoor fan 108 can be an axial flow fan, a cross flow fan or other optional fan types. The outdoor fan 108 is arranged near the outdoor heat exchanger 106.

[0064] The gas-liquid separator is provided on the suction side of the compressor 100 and is a shell-shaped component for separating and storing the gas and liquid of the refrigerant. The gas-liquid separator can store excess refrigerant.

[0065] An outdoor control circuit is provided in the outdoor unit 102. The outdoor control circuit is provided in an electrical box with good sealing performance and heat dissipation function. The outdoor control circuit includes components such as a processor, a storage unit, an input / output interface, and a communication interface. The processor may be a dedicated processor, a central processing unit (CPU), etc. The processor may access the storage unit to execute instructions or applications stored in the storage unit to implement related functions. The storage unit may include a volatile memory and / or a non-volatile memory. The input / output interface may be connected to various sensors provided in the outdoor unit 102 in communication to receive detection values ​​of various sensors provided in the outdoor unit 102. The input / output interface may also be connected to devices such as a frequency converter, a compressor 100, an outdoor fan 108, a reversing valve 110, and a throttling element 112 in communication to output control instructions generated by the processor to them. The communication interface can support different wireless communication protocols, such as Wi-Fi, Bluetooth, near-field communication, NB-IoT, etc., to communicate with other electronic devices, including but not limited to cloud servers, computers (host computers), smart phones, tablets, PDAs, smart control tools, wearable devices and vehicle-mounted equipment, etc.

[0066] The structure and function of the indoor unit 104 are described below, taking one indoor unit 104 as an example. The following description is also applicable to other indoor units 104.

[0067] The indoor unit 104 performs cooling operation or heating operation using the energy generated by the outdoor unit 102 to increase the indoor temperature or the energy to reduce the indoor temperature. The indoor unit 104 includes an indoor heat exchanger 114. The indoor heat exchanger 114 can exchange heat with air or water. An indoor fan 116 is arranged near the indoor heat exchanger 114 to send heated or cooled air to the air-conditioned room. The indoor fan 116 can be an axial flow fan or a cross flow fan, or other fans that can achieve the same function.

[0068] The indoor heat exchanger 114 functions as a condenser in the heating operation and functions as an evaporator in the cooling operation.

[0069] When the indoor heat exchanger 114 is used as a condenser in the heating operation, in one or more embodiments of the present application, Figure 1 and Figure 2As shown, the refrigerant in the indoor heat exchanger 114 exchanges heat with the air guided by the indoor fan 116, so that the refrigerant therein undergoes a phase change (condensation or evaporation). The indoor unit 104 can adopt a wall-mounted air supply structure, a floor-standing air supply structure, a duct-type air supply structure, an air supply structure embedded in the ceiling, etc. The air supply structure includes a shell, a return air port for sucking air from the shell, and an air supply port for sending the heat-exchanged air into the air-conditioned room.

[0070] Figure 3 A schematic diagram showing the structure of a refrigeration system 1 provided in one or more embodiments of the present invention; Figure 4 An example of a refrigerant circuit formed by the refrigeration system 1 according to the embodiment of the present invention (operating in a heating mode) is shown.

[0071] When the indoor heat exchanger 118 is used as a condenser in the heating operation, in one or more embodiments of the present application, Figure 3 and Figure 4 As shown, the refrigerant in the indoor heat exchanger 118 exchanges heat with the water in the pipeline (including the water tank), causing the refrigerant therein to undergo a phase change (condensation or evaporation). The water tank can be used to store hot water for heating and hot water use. When the refrigeration system 1 operates as a heat pump, it can transfer heat energy to the water tank to heat it up, and then supply the hot water to the building or other applications. The size and design of the water tank can vary depending on the specific application site. It can be a simple water storage tank or a more complex hot water storage and distribution system, depending on the needs and performance requirements of the system. When the indoor heat exchanger 118 is used as a condenser in heating operation, the indoor heat exchanger 118 is a water-fluorine plate heat exchanger with the following features: Figure 3 and Figure 4 An inlet pipe 120 and an outlet pipe 122 are shown.

[0072] An indoor control circuit is provided in the indoor unit 104. The indoor control circuit is provided in an electrical box with good sealing performance and heat dissipation function. The indoor control circuit includes components such as a processor, a storage unit, an input / output interface, and a communication interface. The processor may be a dedicated processor, a central processing unit (CPU), etc. The processor may access the storage unit to execute instructions or applications stored in the storage unit to implement related functions. The storage unit may include a volatile memory and / or a non-volatile memory. The input / output interface may be connected to various sensors provided in the indoor unit 104 to receive detection values ​​of various sensors provided in the indoor unit 104. The communication interface may support different wireless communication protocols, such as Wi-Fi, Bluetooth, etc.

[0073] like Figures 1 to 4As shown, in one or more embodiments of the present application, a filter element 124 is provided in the refrigerant circuit. In the refrigerant circuit, the R290 refrigerant circulates sequentially through the compressor 100, the condenser, the throttling element 112, the filter element 124 and the evaporator. In the refrigerant branch 126, the R290 refrigerant sequentially enters the evaporator through the compressor 100, the regulating valve 128 and the filter element 124.

[0074] like Figure 5 and Figure 6 As shown, in one or more embodiments of the present application, a first filter element 130 and a second filter element 132 are provided in the refrigerant circuit. In the refrigerant circuit, the R290 refrigerant circulates sequentially through the compressor 100, the condenser, the first filter element 130, the throttling element 112, the second filter element 132 and the evaporator. In the refrigerant branch 126, the R290 refrigerant enters the evaporator sequentially through the compressor 100, the regulating valve 128 and the second filter element 132.

[0075] In one or more embodiments of the present application, the filter element 124 is a filter with a mesh size of 100 or more and is a bidirectional filter.

[0076] In one or more embodiments of the present application, the first filter element 130 and the second filter element 132 are both filters with a mesh size of 100 or more and are bidirectional filters.

[0077] First embodiment:

[0078] like Figure 7 As shown, different from the prior art, in one or more embodiments of the present application, the refrigeration system 1 further comprises a temperature detection unit 200 and a control unit 300. The temperature detection unit 200 is configured to detect the refrigerant temperature between the throttling element 112 and the filter element 124 (or the second filter element 132) and output an intervention trigger signal when the detection value is below a first predetermined value, and stop outputting the intervention trigger signal when the detection value is above the first predetermined value. The control unit 300 is configured to perform intervention control when the temperature detection unit 200 outputs the intervention trigger signal.

[0079] In one or more embodiments of the present application, the intervention control is: controlling the regulating valve 128 to open the refrigerant branch 126 to increase the refrigerant temperature of R290 flowing into the filter element 124 (or the second filter element 132) under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the output of the intervention trigger signal.

[0080] Figure 8A timing diagram of the refrigeration system 1 provided for one or more embodiments of the present application, wherein Te1 represents the detected value of the refrigerant temperature between the throttling element 112 and the filter element 124 (or the second filter element 132), and Temin represents the first predetermined value. The temperature detection unit 200 outputs an intervention trigger signal at point P1 (Te1≤Temin) and stops outputting the trigger intervention signal at point P2 (Te1>Temin), and the time interval between the two is t1. The control unit 300 is configured to perform intervention control when the temperature detection unit 200 outputs the intervention trigger signal, and control the regulating valve 128 to open the refrigerant branch 126 under the condition that it is greater than the time interval between outputting the intervention trigger signal and stopping outputting the intervention trigger signal (for example, t2 as shown in the figure) to increase the refrigerant temperature of R290 flowing into the filter element 124 (or the second filter element 132).

[0081] Through the cooperation of the temperature detection unit 200 and the control unit 300, the high-temperature and high-pressure gaseous refrigerant is guided to between the throttling element 112 and the filter element 124, thereby increasing the temperature of the refrigerant and avoiding a sudden drop in the temperature of the refrigerating machine oil near the throttling element 112, thereby reducing the risk of condensation and fluidity reduction of the refrigerating machine oil; the prior art adopts open-loop control for the "flash" phenomenon, which cannot ensure the properties of the mixed gas, that is, it cannot ensure that the intervention control to prevent oil blockage is effective. Introducing high-temperature and high-pressure gaseous refrigerant downstream of the throttling element 112 can reduce the possibility of condensation inside the throttling element 112, avoid causing blockage or failure of the throttling element 112, and affect the performance of the system. In addition, in the heating mode, this means that when the intervention control is performed, the refrigerant temperature in the evaporator will be slightly higher than that of the conventional control. The higher evaporation temperature helps to prevent frost or frost on the evaporator surface, thereby reducing the frequency of defrosting, improving the efficiency of the evaporator, and reducing energy loss. Controlling the conduction of the regulating valve 128 under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the outputting of the intervention trigger signal can ensure that the refrigerant temperature is higher than the pour point temperature of the refrigeration oil and has a certain distance from it. At the same time, it can also avoid the original blockage of the pipeline causing uneven flow of the refrigerant in the system, causing uneven temperature distribution, resulting in partial overcooling and further aggravating the blockage.

[0082] In one or more embodiments of the present application, the first predetermined value is higher than the pour point of the refrigeration oil, for example, 3°C higher than the pour point of the refrigeration oil, that is, the temperature difference between the first predetermined value and the pour point is 3°C.

[0083] Refrigeration oil can be polyester oil, polyetherketone oil, etc. The pour point is related to the specific formula and product, and the specific temperature value is not limited here.

[0084] like Figure 7As shown, in one or more embodiments of the present application, the temperature sensor 134 for detecting the refrigerant temperature between the throttling element 112 and the filter element 124 is arranged at 50 mm away from the electronic expansion valve. The detection value at this position can avoid the influence of heat transfer of the refrigerant upstream of the throttling element 112, accurately detect the temperature of the refrigerant after throttling, and the refrigerant pressure drop between the throttling element 112 and the filter element 124 is relatively small, which has little impact on the detection accuracy, thereby ensuring the accuracy of temperature feedback.

[0085] In one or more embodiments of the present application, the temperature detection unit 200 is further configured to output a release trigger signal when the control unit 300 performs intervention control and the detection value is above a second predetermined value higher than the first predetermined value. The control unit 300 is configured to perform recovery control when the temperature detection unit 200 outputs the release trigger signal, and control the regulating valve 128 to close the refrigerant branch 126 to maintain the temperature of the refrigerant flowing into the filter element 124.

[0086] like Figure 8 As shown, where Temax represents a second predetermined value. The temperature detection unit 200 outputs a release trigger signal at point P3 (Te1 ≥ Temax), and the control unit 300 is configured to perform recovery control when the temperature detection unit 200 outputs the release trigger signal, and control the regulating valve 128 to close the refrigerant branch 126 to maintain the temperature of the refrigerant flowing into the filter element 124.

[0087] The second preset value is preferably set to be higher than 20°C above the pour point of the refrigeration oil; that is, the difference between the first preset value and the pour point of the refrigeration oil is smaller than the difference between the second preset value and the first preset value; the numerical setting of the second preset value can ensure that after the refrigerant branch 126 is shut off, even if there is still a "flash" phenomenon, the sudden drop in temperature at the throttling element 112 can be recognized by the temperature detection unit 200 and there is enough time to intervene in the control of the regulating valve 128 through the control unit 300, thereby ensuring that the refrigerant mixed with the refrigeration oil at the throttling element 112 and the filter element 124 still has a certain fluidity.

[0088] In some extreme cases, the temperature of the refrigerant between the throttling element 112 and the filter element 124 cannot rise. Since the refrigeration oil plays an important role in the operation of the compressor 100, the lubrication of the cylinder and the rotor, the prevention of wear, the airtightness, the rust and corrosion prevention, and the cooling and heat dissipation are all inseparable from the refrigeration oil. If the system oil return is not smooth, it will cause irreversible wear to the moving parts of the compressor 100. In severe cases, the wear iron filings will cause the refrigeration system 1 to be blocked, damage the enameled wire of the motor, and burn the motor due to excessive temperature. To avoid this situation, the temperature detection unit 200 is also configured to perform intervention control in the control unit 300, and output a protection trigger signal when the detection value is below a third predetermined value lower than the first predetermined value. The control unit 300 is configured to control the compressor 100 to stop running while performing the intervention control. The third predetermined value is not lower than the pour point of the refrigeration oil, for example, it can be a temperature slightly higher than the pour point, or it can be a pour point temperature, such as -40°C.

[0089] Fig. 9 A timing diagram of the refrigeration system 1 provided in one or more embodiments of the present application, wherein Te1 represents the detected value of the refrigerant temperature between the throttling element 112 and the filter element 124 (or the second filter element 132), and Toilmin represents the third predetermined value. The temperature detection unit 200 outputs a protection trigger signal at the point P4 (Te1≤Toilmin), and the control unit 300 is configured to control the compressor 100 to stop running while performing the intervention control.

[0090] In one or more embodiments of the present application, the temperature detection unit 200 and the control unit 300 are implemented by an indoor control circuit, and the indoor control circuit is connected to the temperature sensor 134 through an input / output interface. The temperature sensor 134 is arranged between the throttling element 112 and the filter element 124 (or the second filter element 132), and is located 50 mm downstream of the temperature sensor 134.

[0091] Fig.10 is a flow chart of the refrigeration system 1, comprising the following steps: heating start, the outdoor heat exchanger 106 operates as an evaporator, the indoor heat exchanger 114 operates as a condenser, and the air conditioner performs heating operation (such as Fig.10 The opening of the throttling element 112 is a set opening or an initial opening calculated according to a preset algorithm (such as Fig.10 The detection value of the sampling temperature sensor 134 (as shown in step S102); Fig.10 The temperature detection unit 200 determines whether the detection value is below the first preset value (such as Fig.10 When the value is below the first preset value, an intervention trigger signal is output (such as Fig.10The control unit 300 performs intervention control: the control valve 128 is controlled to conduct the refrigerant branch 126 under the condition that the time interval between outputting the intervention trigger signal and stopping the outputting of the intervention trigger signal is greater than the time interval between outputting the intervention trigger signal and stopping the outputting of the intervention trigger signal (such as Fig.10 106); maintaining the detection value of the sampling temperature sensor 134 (such as Fig.10 The temperature detection unit 200 determines whether the detected value is below a third preset value (such as Fig.10 When the value is below the third preset value, a protection trigger signal is output (such as Fig.10 The control unit 300 performs protection control: the compressor 100 is controlled to stop running (as shown in step S109); Fig.10 The temperature detection unit 200 also determines whether the detection value is above a second preset value (such as Fig.10 When the value is above the second preset value, a trigger signal is output (such as Fig.10 The control unit 300 performs recovery control: the control valve 128 is controlled to shut off the refrigerant branch 126 to maintain the temperature of the refrigerant flowing into the filter element 124. Fig.11 As shown, in one or more embodiments of the present application, the regulating valve 128 may be a solenoid valve, and a pressure reducing element 136 is further provided on the refrigerant branch 126, which allows the R290 refrigerant to enter the evaporator via the compressor 100, the regulating valve 128, the pressure reducing element 136, and the filter element 124. The pressure reducing element 136 may be a capillary tube.

[0092] In one or more embodiments of the present application, the regulating valve 128 may be an electronic expansion valve.

[0093] After the defrost operation, a large amount of low-temperature liquid refrigerant and refrigeration oil are accumulated in the indoor heat exchanger 114 (working in the evaporator state during the defrost operation). After the defrost operation is completed, the reversing valve 110 is actuated, and the indoor heat exchanger 114 is switched to working in the condenser state, which causes a large amount of low-temperature liquid refrigerant and refrigeration oil accumulated therein to pass through the throttling element 112, and the refrigerant pressure drops rapidly, and some liquid refrigerant flashes, and the temperature of the throttling element 112 drops rapidly, which is very likely to be lower than the pour point of the refrigeration oil, affecting the flow of the refrigeration oil in the throttling element 112 and the filter element 124, and even causing oil blockage.

[0094] To solve this problem, Fig.12 As shown, the control unit 300 is configured to first control the outdoor heat exchanger 106 located in the outdoor unit 102 to operate as an evaporator, and the indoor heat exchanger 114 located in the indoor unit 104 to operate as a condenser (performing a normal heating mode), as shown in FIG. Fig.12Then control the outdoor heat exchanger 106 located in the outdoor unit 102 to operate as a condenser, and the indoor heat exchanger 114 located in the indoor unit 104 to operate as an evaporator to melt the surface frost layer of the outdoor heat exchanger 106 (perform defrosting), such as Fig.12 Then control the outdoor heat exchanger 106 located in the outdoor unit 102 to operate as an evaporator, and the indoor heat exchanger 114 located in the indoor unit 104 to operate as a condenser (re-execute the normal heating mode after defrosting), such as Fig.12 As shown in step S203, when the temperature detection unit 200 outputs the intervention trigger signal, the intervention control is performed: the regulating valve 128 is controlled to conduct the refrigerant branch 126 under the condition that the time interval between outputting the intervention trigger signal and stopping outputting the intervention trigger signal is greater than that between outputting the intervention trigger signal and stopping outputting the intervention trigger signal to increase the temperature of the refrigerant flowing into the filter element 124. In this way, it can be ensured that after each defrosting, the temperature of the throttling element 112 will not drop suddenly and block the pipeline.

[0095] Second embodiment

[0096] For the refrigeration system 1, the emergency shutdown of the compressor 100 is a control method that seriously affects the user experience, especially when the temperature is low, the emergency shutdown of the compressor 100 will cause the indoor temperature to drop rapidly. In the above-mentioned first embodiment of the present application, the control unit 300 is configured to output a protection trigger signal when the control unit 300 performs intervention control and the detection value is below a third predetermined value that is lower than the first predetermined value. When the control unit 300 performs intervention control, the compressor 100 is controlled to stop running. However, this situation may also be caused by the failure of the control of the regulating valve 128 (hardware failure or communication failure) or the refrigerant branch 126 being blocked by iron filings, etc., resulting in the inability to drain normally, further causing the temperature between the throttling element 112 and the regulating element to be unable to rise normally. At this time, it is impossible to distinguish the cause of the fault in time. If the compressor 100 is directly controlled to stop, it will affect the user experience. To solve this problem, the following control method is proposed in one or more embodiments of the present application.

[0097] Fig.13 FIG. 4 is a flow chart of the second embodiment.

[0098] For ease of description, the intervention control in the first embodiment is defined as the first intervention control. That is, the control unit 300 is configured to execute the first intervention control (eg, Fig.13 The first intervention control is: controlling the regulating valve 128 to conduct the refrigerant branch 126 to increase the temperature of the R290 refrigerant flowing into the filter element 124 under the condition that the time interval between outputting the intervention trigger signal and stopping outputting the intervention trigger signal is greater than that between outputting the intervention trigger signal and stopping outputting the intervention trigger signal.

[0099] The temperature detection unit 200 is further configured to determine whether the detection value is below a fourth preset value (such as Fig.13 The temperature detection unit 200 outputs a standby control trigger signal (such as Fig.13 The fourth predetermined value is set not higher than the first predetermined value but higher than the third predetermined value. For example, the first predetermined value may be set higher than the pour point by 5°C, the fourth predetermined value may be set higher than the pour point by 3°C, and the third predetermined value may be set higher than the pour point by 1°C. The control unit 300 is configured to execute the second intervention control (such as Fig.13 (as shown in step S312).

[0100] The second intervention control includes: estimating the temperature difference between the detected value and the third predetermined value; pre-storing a data table with one-to-one correspondence between the temperature difference and the first adjustment coefficient in the storage unit, searching and calling the corresponding first adjustment coefficient in the data table according to the temperature difference, and increasing the opening of the throttling element 112 based on the first adjustment coefficient.

[0101] In one or more embodiments of the present application, increasing the opening of the throttling element 112 based on the first adjustment coefficient includes: assuming that the opening of the throttling element 112 after adjustment is represented by D1, the opening of the throttling element 112 before adjustment is represented by DO, and the first adjustment coefficient is K1, then D1=DO×K1. The data table is pre-set and stored, and the data table satisfies the trend that the temperature difference and the first adjustment coefficient are negatively correlated, that is, the larger the temperature difference, the smaller the first adjustment coefficient.

[0102] In one or more embodiments of the present application, the detection value of the sampling temperature sensor 134 is continued to be maintained, and the temperature detection unit 200 estimates whether the detection value is below a third preset value (such as Fig.13 As shown in step S313 in the figure, the temperature detection unit 200 outputs a protection trigger signal (such as when the temperature detection unit 200 performs the second intervention control when the control unit 300 performs the second intervention control and the detection value is below the third predetermined value). Fig.13 The control unit 300 controls the compressor 100 to stop running (as shown in step S314). Fig.13 In this case, it can be identified that the oil blocking prevention control failure is not caused by the blockage of the refrigerant branch 126, and the refrigeration system 1 has a serious problem and needs to be shut down for maintenance.

[0103] In one or more embodiments of the present application, the detection value of the sampling temperature sensor 134 is continued to be maintained, and the temperature detection unit 200 estimates whether the detection value is above the first preset value (such as Fig.13In step S317), the temperature detection unit 200 is further configured to output a hold trigger signal (such as when the control unit 300 performs a second intervention control and the detection value is above a first predetermined value) when the control unit 300 performs a second intervention control and the detection value is above a first predetermined value. Fig.13 The control unit 300 is configured to execute the hold control (such as step S318) when the temperature detection unit 200 outputs the hold trigger signal. Fig.13 The maintenance control includes: calculating the suction superheat based on the suction temperature of the compressor 100 and the coil temperature of the outdoor heat exchanger 106, estimating whether the suction superheat is not higher than the set superheat, and when the suction superheat is not higher than the set superheat, calling the pre-stored second adjustment coefficient to reduce the opening of the throttling element 112 until the suction superheat is higher than the set superheat, and maintaining the opening of the throttling element 112 until the set cycle ends. In this case, it can be identified that normal intervention adjustment cannot be performed through the refrigerant branch 126, and the first intervention control is in a failed state, and oil blockage prevention can be achieved without stopping the machine.

[0104] In one or more embodiments of the present application, reducing the opening of the throttling element 112 based on the second adjustment coefficient includes: assuming that the opening of the throttling element 112 after adjustment is D2, the opening of the throttling element 112 before adjustment is D1, and the second adjustment coefficient is K2, then D2=D1×K2; wherein 0.8≤K2<1.

[0105] The second intervention control reduces the pressure loss at the throttling element 112 and increases the temperature of the throttling element 112 by adjusting the opening of the throttling element 112. When the first intervention control fails, the temperature at the throttling element 112 is kept not lower than the pour point of the refrigeration oil, which can also prevent oil blockage. At the same time, the suction superheat is controlled to be higher than the set superheat, which avoids the throttling element 112 from opening too large and the liquid return phenomenon at the suction end of the compressor 100, thereby protecting the compressor 100 from damage.

[0106] In one or more embodiments of the present application, the suction superheat may also be calculated based on the suction temperature of the compressor 100 and the saturation temperature corresponding to the suction pressure of the compressor 100 .

[0107] In one or more embodiments of the present application, the superheat is set to 0°C.

[0108] Third embodiment

[0109] In one or more embodiments of the present application, only the second intervention control may be used to maintain the temperature at the throttling element 112 not lower than the pour point of the refrigeration oil.

[0110] Fig.14 and Fig.15 This is a flow chart of a refrigeration system 1 provided in the third embodiment.

[0111] Different from the prior art, in one or more embodiments of the present application, the refrigeration system 1 further comprises a temperature detection unit 200 and a control unit 300. The temperature detection unit 200 is configured to detect the refrigerant temperature between the throttling element 112 and the filter element 124 (or the second filter element 132) and output an adjustment trigger signal (such as a temperature detection unit 200) when the detected value is below a first predetermined value. Fig.14 The control unit 300 is configured to perform adjustment control when the temperature detection unit 200 outputs an adjustment trigger signal (such as Fig.14 (as shown in step S406).

[0112] In one or more embodiments of the present application, the regulation control includes: estimating the temperature difference between the detection value and the third predetermined value; searching and calling the corresponding first regulation coefficient in the data table according to the temperature difference; increasing the opening of the throttling element 112 based on the first regulation coefficient; the data table is pre-stored in the storage unit, which is a data table in which the temperature difference and the first regulation coefficient correspond one to one.

[0113] An example of a data table in the third embodiment is as follows Fig.16 As shown, when the temperature difference is 3°C, the first adjustment coefficient K1 is 1.3; when the temperature difference is 5°C, the first adjustment coefficient K2 is 1.2; when the temperature difference is 7°C, the first adjustment coefficient K2 is 1.1.

[0114] In one or more embodiments of the present application, increasing the opening of the throttling element 112 based on the first adjustment coefficient includes: assuming that the opening of the throttling element 112 after adjustment is represented by D1, the opening of the throttling element 112 before adjustment is represented by DO, and the first adjustment coefficient is K1, then D1=DO×K1. The data table is pre-set and stored, and the data table satisfies the trend that the temperature difference and the first adjustment coefficient are negatively correlated, that is, the larger the temperature difference, the smaller the first adjustment coefficient.

[0115] In one or more embodiments of the present application, the temperature detection unit 200 is further configured to output a hold trigger signal (such as when the control unit 300 performs adjustment control and the detection value is above a first predetermined value) when the control unit 300 performs adjustment control and the detection value is above a first predetermined value. Fig.14 The control unit 300 is configured to execute the hold control (such as step S412) when the temperature detection unit 200 outputs the hold trigger signal. Fig.14 (as shown in step S413).

[0116] In one or more embodiments of the present application, maintaining control includes: estimating whether the intake superheat is not higher than the set superheat; when the intake superheat is not higher than the set superheat, calling a pre-stored second adjustment coefficient to reduce the opening of the throttling element 112 until the intake superheat is higher than the set superheat, and maintaining the opening of the throttling element 112 until the set cycle ends.

[0117] In one or more embodiments of the present application, reducing the opening of the throttling element 112 based on the second adjustment coefficient includes: the opening of the throttling element 112 after adjustment is D2, the opening of the throttling element 112 before adjustment is D1, and the second adjustment coefficient is K2, then D2=D1×K2; wherein 0.8≤K2<1.

[0118] In one or more embodiments of the present application, the control unit 300 is further configured to output a protection trigger signal (such as a protection trigger signal) when the adjustment control is performed and the detection value is below a third predetermined value that is lower than the first predetermined value. Fig.14 The control unit 300 is configured to control the compressor 100 to stop running while performing the regulation control (such as Fig.14 The third predetermined value may be a temperature slightly higher than the pour point, or may be the pour point temperature, such as -40°C.

[0119] In one or more embodiments of the present application, the control unit 300 is configured to calculate the suction air superheat based on the suction air temperature of the compressor 100 and the coil temperature of the outdoor heat exchanger 106 .

[0120] In one or more embodiments of the present application, the control unit 300 is configured to calculate the suction superheat based on the suction temperature of the compressor 100 and the saturation temperature corresponding to the suction pressure of the compressor 100 .

[0121] The regulating control reduces the pressure loss at the throttling element 112, increases the temperature of the throttling element 112, and maintains the temperature at the throttling element 112 not lower than the pour point of the refrigeration oil by adjusting the opening of the throttling element 112. This can also prevent oil blockage, while controlling the suction superheat to be higher than the set superheat, avoiding excessive opening of the throttling element 112 and liquid return at the suction end of the compressor 100, thereby protecting the compressor 100 from damage.

[0122] In one or more embodiments of the present application, the superheat is set to 0°C.

[0123] The method proposed in the third embodiment is preferably performed after defrosting. The specific process is as follows: Fig.15 As shown, no further description is given here.

[0124] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0125] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. Refrigeration system, with: a refrigerant circuit for circulating the refrigerant sequentially through a compressor, a condenser, a throttling element, a filter element and an evaporator, wherein the condenser exchanges heat with air; It is characterized in that Also available: A refrigerant branch, which supplies refrigerant to the evaporator via the compressor, the regulating valve, and the filter element in sequence; a temperature detection unit configured to detect a refrigerant temperature between the throttling element and the filter element; output an intervention trigger signal when the detection value is below a first predetermined value, and stop outputting the intervention trigger signal when the detection value is above the first predetermined value; and a control unit configured to perform intervention control when the temperature detection unit outputs the intervention trigger signal: controlling the regulating valve to conduct the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under a condition that is greater than a time interval between outputting the intervention trigger signal and stopping outputting the intervention trigger signal; Wherein, the first predetermined value is higher than the pour point of the refrigeration oil.

2. The refrigeration system according to claim 1, characterized in that: The temperature detection unit is further configured to output a release trigger signal when the control unit performs intervention control and the detection value is above a second predetermined value that is higher than the first predetermined value; The control unit is configured to perform recovery control when the temperature detection unit outputs the release trigger signal: controlling the regulating valve to close the refrigerant branch to maintain the temperature of the refrigerant flowing into the filter element; The difference between the first predetermined value and the pour point of the refrigeration oil is smaller than the difference between the second predetermined value and the first predetermined value.

3. The refrigeration system according to claim 2, The control unit is also configured to: first control the outdoor heat exchanger located in the outdoor unit to operate as an evaporator, and the indoor heat exchanger located in the indoor unit to operate as a condenser; then control the outdoor heat exchanger located in the outdoor unit to operate as a condenser, and the indoor heat exchanger located in the indoor unit to operate as an evaporator to melt the surface frost layer of the outdoor heat exchanger; then control the outdoor heat exchanger located in the outdoor unit to operate as an evaporator, and the indoor heat exchanger located in the indoor unit to operate as a condenser, and at the same time, perform intervention control when the temperature detection unit outputs the intervention trigger signal: control the regulating valve to open the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the output of the intervention trigger signal.

4. The refrigeration system according to claim 1, The temperature detection unit is further configured to perform intervention control in the control unit, and output a protection trigger signal when the detection value is below a third predetermined value that is lower than the first predetermined value; Under the condition that the temperature detection unit outputs a protection trigger signal, the control unit is configured to control the compressor to stop running while executing the intervention control; The third predetermined value is not lower than the pour point of the refrigeration oil.

5. The refrigeration system according to claim 1, The refrigerant branch is also provided with a pressure reducing element, which allows the refrigerant to enter the evaporator via the compressor, the regulating valve, the pressure reducing element and the filter element in sequence.

6. Refrigeration system, with: a refrigerant circuit, in which the refrigerant circulates sequentially through a compressor, a condenser, a throttling element, a filter element and an evaporator, wherein the condenser exchanges heat with water; It is characterized in that Also available: A refrigerant branch, which supplies refrigerant to the evaporator via the compressor, the regulating valve, and the filter element in sequence; a temperature detection unit configured to detect the refrigerant temperature between the throttling element and the filter element; and output an intervention trigger signal when the detection value is below a first predetermined value, and stop outputting the intervention trigger signal when the detection value is above the first predetermined value; and a control unit configured to perform intervention control when the temperature detection unit outputs the intervention trigger signal: controlling the regulating valve to conduct the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under a condition that is greater than a time interval between outputting the intervention trigger signal and stopping outputting the intervention trigger signal; Wherein, the first predetermined value is higher than the pour point of the refrigeration oil.

7. The refrigeration system according to claim 6, characterized in that: The temperature detection unit is further configured to output a release trigger signal when the control unit performs intervention control and the detection value is above a second predetermined value that is higher than the first predetermined value; The control unit is configured to perform recovery control when the temperature detection unit outputs the release trigger signal: controlling the regulating valve to close the refrigerant branch to maintain the temperature of the refrigerant flowing into the filter element; The difference between the first predetermined value and the pour point of the refrigeration oil is smaller than the difference between the second predetermined value and the first predetermined value.

8. The refrigeration system according to claim 7, The control unit is also configured to: first control the outdoor heat exchanger located in the outdoor unit to operate as an evaporator, and the indoor heat exchanger located in the indoor unit to operate as a condenser; then control the outdoor heat exchanger located in the outdoor unit to operate as a condenser, and the indoor heat exchanger located in the indoor unit to operate as an evaporator to melt the surface frost layer of the outdoor heat exchanger; then control the outdoor heat exchanger located in the outdoor unit to operate as an evaporator, and the indoor heat exchanger located in the indoor unit to operate as a condenser, and at the same time, perform intervention control when the temperature detection unit outputs the intervention trigger signal: control the regulating valve to open the refrigerant branch to increase the temperature of the refrigerant flowing into the filter element under the condition that the time interval is greater than the time interval between outputting the intervention trigger signal and stopping the output of the intervention trigger signal.

9. The refrigeration system according to claim 6, The control unit is further configured to perform intervention control at the control unit, and output a protection trigger signal when the detection value is below a third predetermined value that is lower than the first predetermined value; Under the condition that the temperature detection unit outputs a protection trigger signal, the control unit is configured to control the compressor to stop running while executing the intervention control; The third predetermined value is not lower than the pour point of the refrigeration oil.

10. The refrigeration system according to claim 6, The refrigerant branch is also provided with a pressure reducing element, which allows the refrigerant to enter the evaporator via the compressor, the regulating valve, the pressure reducing element and the filter element in sequence.

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