Refrigerating system, oil return control method and device thereof, storage medium and program product

Abstract

The invention discloses an oil return control method and device of a refrigerating system, the refrigerating system, a storage medium and a computer program product, the refrigerating system comprises a plurality of evaporators arranged in parallel, a branch where each evaporator is located is provided with a throttling component, and the evaporators are used for refrigerating different inner cabinets; the method comprises the steps that when a system runs, whether an oil return mode is started or not is determined according to the running frequency of a compressor, if it is determined that the oil return mode is started, the running frequency of the compressor is controlled to be the oil return frequency, the running state of an inner cabinet is controlled, and then the minimum value of the opening degree of a throttling component is controlled according to the temperature in the inner cabinet. According to the scheme, refrigeration oil in all evaporators is removed by controlling the operation state of the inner cabinet and the minimum opening value of the throttling component during oil return, the oil return amount of the compressor and the refrigeration effect of the evaporators are improved, and stable and reliable operation of the system is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of refrigeration systems, and specifically relates to an oil return control method, device, refrigeration system, storage medium and computer program product for a refrigeration system, and in particular to an oil return control method, device, refrigeration system, storage medium and computer program product for a refrigeration system applied to a multi-link display cabinet. Background Art

[0002] In the refrigeration system, when the compressor is working, a small amount of refrigerant oil will be continuously pressed out of the cylinder together with the refrigerant, and enter the pipelines, condensers and evaporators of the refrigeration system. When the refrigerant oil cannot be continuously returned to the compressor, the oil level of the compressor will drop, the compressor performance will decline, the internal components will be aggravated, and the operating life of the compressor will be affected.

[0003] The multi-split display cabinet adopts a one-to-many refrigeration system. When returning oil, the shut-down indoor units in the system cannot participate in the oil return normally, which not only reduces the oil return volume of the compressor, but also forms a layer of oil film on the inner wall surface of the evaporator of these shut-down indoor units, increasing the thermal resistance, reducing the heat transfer effect of the evaporator, and reducing the refrigeration effect.

[0004] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The object of the present invention is to provide an oil return control method and device for a refrigeration system, a refrigeration system, a storage medium and a computer program product, so as to solve the problem in the related scheme that there are stopped or powered off indoor units in a multi-connected display cabinet using a one-to-many refrigeration system, resulting in the compressor being unable to return oil normally, the compressor performance being reduced, the service life being shortened, and the refrigeration effect of the stopped indoor units being reduced. The method can achieve the effect of removing the refrigerant oil in all evaporators by controlling the operating state of the indoor cabinet and the minimum opening value of the throttling component during oil return, thereby increasing the oil return amount of the compressor and the refrigeration effect of the evaporator, and ensuring the stable and reliable operation of the system.

[0006] The present invention provides an oil return control method for a refrigeration system, the refrigeration system comprising: a compressor and at least two evaporators; the evaporators are arranged in parallel, and a throttling component is arranged on a branch where each of the evaporators is located; each of the evaporators is used to cool a different inner cabinet; the method comprises: obtaining the operating frequency of the compressor and the temperature in the inner cabinet; determining whether to turn on a preset oil return mode according to the operating frequency of the compressor; if it is determined to turn on the preset oil return mode, controlling the operating frequency of the compressor to the preset oil return frequency to control the operating state of the inner cabinet, and then controlling the minimum opening value of the throttling component according to the temperature in the inner cabinet.

[0007] In some embodiments, determining whether to turn on a preset oil return mode is based on the operating frequency of the compressor, including: judging whether the operating frequency of the compressor is less than or equal to the preset operating frequency; if the operating frequency of the compressor is less than or equal to the preset operating frequency and a preset time has accumulated, determining to turn on the preset oil return mode; if the operating frequency of the compressor is greater than the preset operating frequency, determining not to turn on the preset oil return mode.

[0008] In some embodiments, the state of the inner cabinet includes a refrigeration on state and a refrigeration off state; controlling the operating state of the inner cabinet includes: determining whether there is an inner cabinet whose operating state is the refrigeration off state among all the inner cabinets; if there is an inner cabinet whose operating state is the refrigeration off state, switching the operating state of the inner cabinet whose operating state is the refrigeration off state to the refrigeration on state.

[0009] In some embodiments, controlling the minimum opening value of the throttling component according to the temperature in the inner cabinet includes: judging the relationship between the temperature in the inner cabinet and a preset temperature; if the temperature in the inner cabinet is greater than the preset temperature, controlling the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located to be a preset first opening; if the temperature in the inner cabinet is less than or equal to the preset temperature, controlling the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located to be a preset second opening; the preset first opening>the preset second opening.

[0010] In some embodiments, the method further includes: exiting the preset oil return mode after the continuous operation time in the preset oil return mode is greater than the preset time.

[0011] Matching the above method, the present invention provides an oil return control device for a refrigeration system on the other hand, the refrigeration system comprising: a compressor and at least two evaporators; the evaporators are arranged in parallel, and a throttling component is provided on the branch where each evaporator is located; each evaporator is used to cool a different internal cabinet; the device comprises: an acquisition unit, configured to acquire the operating frequency of the compressor and the temperature control unit in the internal cabinet, configured to determine whether to turn on a preset oil return mode according to the operating frequency of the compressor; the control unit is further configured to control the operating frequency of the compressor to the preset oil return frequency if it is determined to turn on the preset oil return mode; the control unit is further configured to control the operating state of the internal cabinet, and then control the minimum opening value of the throttling component according to the temperature in the internal cabinet.

[0012] In some embodiments, the control unit determines whether to turn on the preset oil return mode according to the operating frequency of the compressor, including: judging whether the operating frequency of the compressor is less than or equal to the preset operating frequency; if the operating frequency of the compressor is less than or equal to the preset operating frequency and the preset time has accumulated, determining to turn on the preset oil return mode; if the operating frequency of the compressor is greater than the preset operating frequency, determining not to turn on the preset oil return mode.

[0013] In some embodiments, the state of the inner cabinet includes a refrigeration on state and a refrigeration off state; the control unit controls the operating state of the inner cabinet, including: determining whether there is an inner cabinet whose operating state is the refrigeration off state among all the inner cabinets; if there is an inner cabinet whose operating state is the refrigeration off state, switching the operating state of the inner cabinet whose operating state is the refrigeration off state to the refrigeration on state.

[0014] In some embodiments, the control unit controls the minimum opening value of the throttling component according to the temperature in the inner cabinet, including: judging the relationship between the temperature in the inner cabinet and a preset temperature; if the temperature in the inner cabinet is greater than the preset temperature, controlling the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located to be a preset first opening; if the temperature in the inner cabinet is less than or equal to the preset temperature, controlling the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located to be a preset second opening; the preset first opening>the preset second opening.

[0015] In some embodiments, the control unit is further configured to exit the preset oil return mode after the continuous operation time in the preset oil return mode is greater than a preset time.

[0016] Matching the above device, the present invention provides a refrigeration system on another aspect, including: the oil return control device of the refrigeration system described above.

[0017] Matching the above refrigeration system, the present invention further provides a display cabinet including the above refrigeration system.

[0018] In accordance with the above method, the present invention provides a storage medium on the other hand, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the above-mentioned oil return control method for the refrigeration system.

[0019] In accordance with the above method, the present invention provides a computer program product on another aspect, wherein the computer program product includes a computer program, and when the computer program product is processed and executed, the steps of the above method for controlling the oil return of the refrigeration system are implemented.

[0020] According to the solution of the present invention, the refrigeration system includes a plurality of evaporators arranged in parallel, each evaporator is provided with a throttling component on the branch, and the evaporators are used to cool different internal cabinets; when the system is running, it is determined whether to turn on the oil return mode according to the operating frequency of the compressor. If it is determined to turn on the oil return mode, the operating frequency of the compressor is controlled to be the oil return frequency, the operating state of the internal cabinet is controlled, and then the minimum opening value of the throttling component is controlled according to the temperature in the internal cabinet. By controlling the operating state of the internal cabinet and the minimum opening value of the throttling component during oil return, the refrigeration oil in all evaporators is removed, the oil return amount of the compressor and the refrigeration effect of the evaporator are increased, and the stable and reliable operation of the system is ensured.

[0021] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic flow chart of an embodiment of an oil return control method for a refrigeration system of the present invention;

[0024] Figure 2 It is a structural schematic diagram of an embodiment of an oil return control device for a refrigeration system of the present invention;

[0025] Figure 3 It is a structural schematic diagram of a multi-type display cabinet refrigeration system;

[0026] Figure 4 It is a flow chart of another embodiment of the oil return control method of the refrigeration system of the present invention.

[0027] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0028] 1- compressor; 2- oil separator; 3- condenser; 4- condensing fan; 5- drying filter; 6- liquid supply stop valve; 7- throttling component; 8- inner cabinet; 9- air intake stop valve; 10- first filter; 11- gas-liquid separator; 12- oil return solenoid valve; 13- oil return capillary; 14- second filter; 102- acquisition unit; 104- control unit. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] According to an embodiment of the present invention, a method for controlling oil return of a refrigeration system is provided, wherein the refrigeration system comprises: a compressor and at least two evaporators; the evaporators are arranged in parallel, and a throttling component is provided on the branch where each evaporator is located; and each evaporator is used to cool different internal cabinets.

[0031] The structure of the refrigeration system is as follows Figure 3 As shown, it is a one-to-many refrigeration system. A separate evaporator is provided in each inner cabinet 8, and the evaporator can cool the inner cabinet in which it is located. All evaporators are arranged in parallel, and a throttling component 7 is provided on the refrigerant inlet side of each evaporator. The throttling component 7 can be an electronic expansion valve, which is used to control the refrigerant flow rate of the evaporator on the branch where it is located. After the refrigeration system starts to operate, the high-temperature and high-pressure refrigerant discharged by the compressor 1 passes through the oil separator 2, the condenser 3, the drying filter 5, and the liquid supply stop valve 6 in sequence, and then flows into each parallel evaporator respectively, cooling each inner cabinet 8. The low-temperature refrigerant flowing out of the evaporator passes through the suction stop valve 9, the first filter 10, and the gas-liquid separator 11 and returns to the compressor 1. Among them, the refrigerant oil in the oil separator 2 can return to the compressor 1 through the oil return capillary 13 and the oil return solenoid valve 12.

[0032] After the refrigeration system is running, each inner cabinet can choose whether to run to reduce the temperature of the inner cabinet. The user can set the inner cabinet to run for cooling and the inner cabinet to not run for cooling. Specifically, when the inner cabinet is set to not run for cooling, the throttling component corresponding to the inner cabinet is closed, and the refrigerant will not flow into the evaporator in the inner cabinet, thereby not providing cooling for the inner cabinet; after the inner cabinet starts running, the throttling component corresponding to the inner cabinet is opened, and the refrigerant flows into the evaporator in the inner cabinet, and the evaporator releases the cooling energy into the inner cabinet.

[0033] like Figure 1 The flow chart of an embodiment of the method of the present invention is shown in FIG. The oil return control method of the refrigeration system may include: steps S110 to S140.

[0034] In step S110, the operating frequency of the compressor and the temperature inside the inner cabinet are obtained.

[0035] In step S120, it is determined whether to start a preset oil return mode according to the operating frequency of the compressor.

[0036] The preset oil return mode is used for compressor oil return and controls the internal cabinets that are not running in the refrigeration system to improve the oil return efficiency.

[0037] In some embodiments, in step S120, the specific process of determining whether to turn on the preset oil return mode according to the operating frequency of the compressor includes: judging whether the operating frequency of the compressor is less than or equal to the preset operating frequency; if the operating frequency of the compressor is less than or equal to the preset operating frequency and the preset time has accumulated, determining to turn on the preset oil return mode; if the operating frequency of the compressor is greater than the preset operating frequency, determining not to turn on the preset oil return mode.

[0038] When the compressor runs at a low frequency for a long time, oil will accumulate in the pipeline, and the refrigerant oil may not be able to return in time, resulting in the compressor being short of oil. Therefore, when the compressor runs for a period of time at a frequency less than or equal to the preset operating frequency, the oil return mode is turned on to return the oil. If the operating frequency of the compressor is greater than the preset operating frequency, it is considered that the flow rate of the refrigerant is high and the refrigerant oil can be brought back to the compressor, and there is no need to turn on the oil return mode. In this way, by determining whether to return the oil based on the operating frequency of the compressor, the oil return time can be accurately controlled, the oil return efficiency can be improved, and the compressor life and system performance can be avoided from being affected by the lack of oil in the compressor.

[0039] When the actual operating frequency of the compressor required by the system exceeds the oil return frequency and lasts for a certain period of time, the preset time accumulated when the compressor operating frequency is ≤ the preset operating frequency is reset.

[0040] In step S130, if it is determined to start the preset oil return mode, the operating frequency of the compressor is controlled to be the preset oil return frequency.

[0041] After entering the oil return mode, the compressor increases the frequency to the preset oil return frequency, thereby increasing the refrigerant flow rate and allowing more refrigerant oil to flow back to the compressor along with the refrigerant.

[0042] In step S140, the operating state of the inner cabinet is controlled, and then the minimum opening value of the throttling component is controlled according to the temperature in the inner cabinet.

[0043] This solution controls the operating status of the inner cabinet and the minimum opening value of the throttling component during oil return, removes the refrigerant oil in all evaporators, increases the oil return volume of the compressor and the refrigeration effect of the evaporator, and ensures stable and reliable operation of the system.

[0044] In some embodiments, the state of the inner cabinet includes a refrigeration on state and a refrigeration off state. The refrigeration on state means that the evaporator in the inner cabinet has refrigerant passing through it, and heat exchange is performed and the cold energy is released to the inner cabinet. The refrigeration off state means that the evaporator in the inner cabinet has no refrigerant flowing through it, that is, the throttling component in front of the evaporator is in a closed state, and the temperature in the inner cabinet is not adjusted at this time.

[0045] In some embodiments, in step S140, the specific process of controlling the operating status of the inner cabinet includes: determining whether there is an inner cabinet whose operating status is the refrigeration shutdown status among all the inner cabinets; if there is an inner cabinet whose operating status is the refrigeration shutdown status, switching the operating status of the inner cabinet whose operating status is the refrigeration shutdown status to the refrigeration startup status.

[0046] When the refrigeration system is operating normally, part of the refrigerant oil flows into the evaporator along with the refrigerant. When returning the oil, if these evaporators do not participate in the oil return, the refrigerant oil will not return to the compressor, resulting in a reduction in the amount of returned oil, and the refrigerant oil will also affect the heat exchange efficiency of the evaporator. Therefore, when returning the oil, all the internal cabinets that have been shut down are controlled to start up so that all evaporators participate in the oil return.

[0047] In the oil return mode, the opening of each throttling component is controlled in accordance with the PID control method, and the minimum opening value of the throttling component is adjusted according to the temperature in the inner cabinet.

[0048] In some embodiments, in step S140, the specific process of controlling the minimum opening value of the throttling component according to the temperature in the inner cabinet includes: judging the relationship between the temperature in the inner cabinet and a preset temperature; if the temperature in the inner cabinet is greater than the preset temperature, controlling the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located to be a preset first opening; if the temperature in the inner cabinet is less than or equal to the preset temperature, controlling the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located to be a preset second opening; the preset first opening>the preset second opening.

[0049] During the oil return process, controlling the opening of the throttling component in accordance with the PID control method can meet the demand for oil return. In order to improve the oil return efficiency, it is necessary to increase the minimum opening of the throttling component so that the refrigerant flow rate is large enough. Specifically, when the temperature in the inner cabinet is greater than the preset temperature, the minimum opening value of the throttling component corresponding to the inner cabinet is a higher preset first opening, such as 55%; when the temperature in the inner cabinet is less than or equal to the preset temperature, the minimum opening value of the throttling component corresponding to the inner cabinet is a lower preset second opening, such as 45%. Since the compressor operates at a fixed frequency during the oil return process, that is, the refrigerant flow is fixed, and when the temperature of the inner cabinet is high, by increasing the minimum opening value of the throttling component, more refrigerant is used to cool the inner cabinet; when the temperature of the inner cabinet is low, by reducing the minimum opening value of the throttling component, the temperature reduction speed of the inner cabinet is slowed down, thereby achieving differentiated control of the inner cabinets with different cabinet temperatures.

[0050] When the opening of the throttling component is controlled in accordance with the PID control method, if the opening value of the throttling component obtained by the PID control method is less than the minimum opening value, the system will operate according to the minimum opening value.

[0051] In some embodiments, the method further includes: exiting the preset oil return mode after the continuous operation time in the preset oil return mode is greater than the preset time.

[0052] When the operating time in the oil return mode or the operating time of the compressor at the oil return frequency exceeds the preset time, the oil return is exited.

[0053] In the oil return mode, when the defrost conditions are met, oil return is given priority, and the defrost mode is entered after the oil return is completed.

[0054] After entering the oil return mode, the shutdown condition is not detected, that is, the shutdown mode is not entered when the indoor unit meets the conditions.

[0055] Figure 4 FIG. 1 is a flow chart of another embodiment of the oil return control method for a refrigeration system of the present invention. Figure 4 As shown, the method includes:

[0056] Step 1: Obtain the operating parameters of the indoor and outdoor units and determine whether the compressor operating frequency is ≤f min If the accumulated running time reaches the first limit threshold, the compressor enters the oil return mode and increases the frequency to the oil return frequency.

[0057] Step 2. Determine whether the status of all indoor units is in the cooling on state. If there are indoor units that are not in the cooling on state, these indoor units enter the cooling on state and execute step 3; if the status of all indoor units is in the cooling on state, execute step 3.

[0058] Step 3, control the opening of the electronic expansion valve of all indoor units in accordance with the PID control method, and for each indoor unit, determine whether the temperature of the indoor cabinet is greater than the set temperature. If the temperature of the indoor cabinet is greater than the set temperature, the minimum opening limit of the electronic expansion valve corresponding to the indoor cabinet is set to 55%; if the temperature of the indoor cabinet is less than or equal to the set temperature, the minimum opening limit of the electronic expansion valve corresponding to the indoor cabinet is set to 45%.

[0059] Step 4: when the operation time of the compressor at the oil return frequency exceeds a second defined threshold, exit the oil return mode.

[0060] The technical solution of this embodiment is adopted, and the refrigeration system includes multiple evaporators arranged in parallel, and each evaporator is provided with a throttling component on the branch where the evaporator is located, and the evaporators are used to cool different internal cabinets; when the system is running, it is determined whether to turn on the oil return mode according to the operating frequency of the compressor. If it is determined to turn on the oil return mode, the operating frequency of the compressor is controlled to be the oil return frequency, the operating state of the internal cabinet is controlled, and then the minimum opening value of the throttling component is controlled according to the temperature in the internal cabinet. By controlling the operating state of the internal cabinet and the minimum opening value of the throttling component during oil return, the refrigerant oil in all evaporators is removed, the oil return amount of the compressor and the refrigeration effect of the evaporator are increased, and the stable and reliable operation of the system is ensured.

[0061] According to an embodiment of the present invention, an oil return control device for a refrigeration system corresponding to the oil return control method for the refrigeration system is also provided. The refrigeration system comprises: a compressor and at least two evaporators; the evaporators are arranged in parallel, and a throttling component is arranged on the branch where each evaporator is located; each evaporator is used to cool different internal cabinets.

[0062] The structure of the refrigeration system is as follows Figure 3As shown, it is a one-to-many refrigeration system. A separate evaporator is provided in each inner cabinet 8, and the evaporator can cool the inner cabinet in which it is located. All evaporators are arranged in parallel, and a throttling component 7 is provided on the refrigerant inlet side of each evaporator. The throttling component 7 can be an electronic expansion valve, which is used to control the refrigerant flow rate of the evaporator on the branch where it is located. After the refrigeration system starts to operate, the high-temperature and high-pressure refrigerant discharged by the compressor 1 passes through the oil separator 2, the condenser 3, the drying filter 5, and the liquid supply stop valve 6 in sequence, and then flows into each parallel evaporator respectively, cooling each inner cabinet 8. The low-temperature refrigerant flowing out of the evaporator passes through the suction stop valve 9, the first filter 10, and the gas-liquid separator 11 and returns to the compressor 1. Among them, the refrigerant oil in the oil separator 2 can return to the compressor 1 through the oil return capillary 13 and the oil return solenoid valve 12.

[0063] After the refrigeration system is running, each inner cabinet can choose whether to run to reduce the temperature of the inner cabinet. The user can set the inner cabinet to run for cooling and the inner cabinet to not run for cooling. Specifically, when the inner cabinet is set to not run for cooling, the throttling component corresponding to the inner cabinet is closed, and the refrigerant will not flow into the evaporator in the inner cabinet, thereby not providing cooling for the inner cabinet; after the inner cabinet starts running, the throttling component corresponding to the inner cabinet is opened, and the refrigerant flows into the evaporator in the inner cabinet, and the evaporator releases the cooling energy into the inner cabinet.

[0064] See also Figure 2 The oil return control device of the refrigeration system may include: an acquisition unit 102 and a control unit 104 .

[0065] The acquisition unit 102 is configured to acquire the operating frequency of the compressor and the temperature in the inner cabinet. The specific functions and processing of the acquisition unit 102 refer to step S110.

[0066] The control unit 104 is configured to determine whether to start the preset oil return mode according to the operating frequency of the compressor. The specific functions and processing of the control unit 104 refer to step S120.

[0067] The preset oil return mode is used for compressor oil return and controls the internal cabinets that are not running in the refrigeration system to improve the oil return efficiency.

[0068] In some embodiments, the control unit 104 determines whether to turn on the preset oil return mode according to the specific process of the operating frequency of the compressor, including: judging whether the operating frequency of the compressor is less than or equal to the preset operating frequency; if the operating frequency of the compressor is less than or equal to the preset operating frequency and the preset time has accumulated, determining to turn on the preset oil return mode; if the operating frequency of the compressor is greater than the preset operating frequency, determining not to turn on the preset oil return mode.

[0069] When the compressor runs at a low frequency for a long time, oil will accumulate in the pipeline, and the refrigerant oil may not be able to return in time, resulting in the compressor being short of oil. Therefore, when the compressor runs for a period of time at a frequency less than or equal to the preset operating frequency, the oil return mode is turned on to return the oil. If the operating frequency of the compressor is greater than the preset operating frequency, it is considered that the flow rate of the refrigerant is high and the refrigerant oil can be brought back to the compressor, and there is no need to turn on the oil return mode. In this way, by determining whether to return the oil based on the operating frequency of the compressor, the oil return time can be accurately controlled, the oil return efficiency can be improved, and the compressor life and system performance can be avoided from being affected by the lack of oil in the compressor.

[0070] When the actual operating frequency of the compressor required by the system exceeds the oil return frequency and lasts for a certain period of time, the preset time accumulated when the compressor operating frequency is ≤ the preset operating frequency is reset.

[0071] The control unit 104 is further configured to control the operating frequency of the compressor to a preset oil return frequency if it is determined to start the preset oil return mode. The specific functions and processing of the control unit 104 refer to step S130.

[0072] After entering the oil return mode, the compressor increases the frequency to the preset oil return frequency, thereby increasing the refrigerant flow rate and allowing more refrigerant oil to flow back to the compressor along with the refrigerant.

[0073] The control unit 104 is further configured to control the operating state of the inner cabinet, and then control the minimum opening value of the throttling component according to the temperature in the inner cabinet. The specific functions and processing of the control unit 104 refer to step S140.

[0074] This solution controls the operating status of the inner cabinet and the minimum opening value of the throttling component during oil return, removes the refrigerant oil in all evaporators, increases the oil return volume of the compressor and the refrigeration effect of the evaporator, and ensures stable and reliable operation of the system.

[0075] In some embodiments, the state of the inner cabinet includes a refrigeration on state and a refrigeration off state. The refrigeration on state means that the evaporator in the inner cabinet has refrigerant passing through it, and heat exchange is performed and the cold energy is released to the inner cabinet. The refrigeration off state means that the evaporator in the inner cabinet has no refrigerant flowing through it, that is, the throttling component in front of the evaporator is in a closed state, and the temperature in the inner cabinet is not adjusted at this time.

[0076] In some embodiments, the control unit 104 controls the specific process of the operating status of the inner cabinet, including: determining whether there is an inner cabinet whose operating status is the refrigeration shutdown status among all the inner cabinets; if there is an inner cabinet whose operating status is the refrigeration shutdown status, switching the operating status of the inner cabinet whose operating status is the refrigeration shutdown status to the refrigeration on status.

[0077] When the refrigeration system is operating normally, part of the refrigerant oil flows into the evaporator along with the refrigerant. When returning the oil, if these evaporators do not participate in the oil return, the refrigerant oil will not return to the compressor, resulting in a reduction in the amount of returned oil, and the refrigerant oil will also affect the heat exchange efficiency of the evaporator. Therefore, when returning the oil, all the internal cabinets that have been shut down are controlled to start up so that all evaporators participate in the oil return.

[0078] In the oil return mode, the opening of each throttling component is controlled in accordance with the PID control method, and the minimum opening value of the throttling component is adjusted according to the temperature in the inner cabinet.

[0079] In some embodiments, the control unit 104 controls the specific process of controlling the minimum opening value of the throttling component according to the temperature in the inner cabinet, including: judging the relationship between the temperature in the inner cabinet and a preset temperature; if the temperature in the inner cabinet is greater than the preset temperature, controlling the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located to be a preset first opening; if the temperature in the inner cabinet is less than or equal to the preset temperature, controlling the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located to be a preset second opening; the preset first opening>the preset second opening.

[0080] During the oil return process, controlling the opening of the throttling component in accordance with the PID control method can meet the demand for oil return. In order to improve the oil return efficiency, it is necessary to increase the minimum opening of the throttling component so that the refrigerant flow rate is large enough. Specifically, when the temperature in the inner cabinet is greater than the preset temperature, the minimum opening value of the throttling component corresponding to the inner cabinet is a higher preset first opening, such as 55%; when the temperature in the inner cabinet is less than or equal to the preset temperature, the minimum opening value of the throttling component corresponding to the inner cabinet is a lower preset second opening, such as 45%. Since the compressor operates at a fixed frequency during the oil return process, that is, the refrigerant flow is fixed, and when the temperature of the inner cabinet is high, by increasing the minimum opening value of the throttling component, more refrigerant is used to cool the inner cabinet; when the temperature of the inner cabinet is low, by reducing the minimum opening value of the throttling component, the temperature reduction speed of the inner cabinet is slowed down, thereby achieving differentiated control of the inner cabinets with different cabinet temperatures.

[0081] When the opening of the throttling component is controlled in accordance with the PID control method, if the opening value of the throttling component obtained by the PID control method is less than the minimum opening value, the system will operate according to the minimum opening value.

[0082] In some embodiments, the control unit 104 is further configured to exit the preset oil return mode after the continuous operation time in the preset oil return mode is greater than a preset time.

[0083] When the operating time in the oil return mode or the operating time of the compressor at the oil return frequency exceeds the preset time, the oil return is exited.

[0084] In the oil return mode, when the defrost conditions are met, oil return is given priority, and the defrost mode is entered after the oil return is completed.

[0085] After entering the oil return mode, the shutdown condition is not detected, that is, the shutdown mode is not entered when the indoor unit meets the conditions.

[0086] Figure 4 FIG. 1 is a flow chart of another embodiment of the oil return control method for a refrigeration system of the present invention. Figure 4 As shown, the method includes:

[0087] Step 1: Obtain the operating parameters of the indoor and outdoor units and determine whether the compressor operating frequency is ≤f min If the accumulated running time reaches the first limit threshold, the compressor enters the oil return mode and increases the frequency to the oil return frequency.

[0088] Step 2. Determine whether the status of all indoor units is in the cooling on state. If there are indoor units that are not in the cooling on state, these indoor units enter the cooling on state and execute step 3; if the status of all indoor units is in the cooling on state, execute step 3.

[0089] Step 3, control the opening of the electronic expansion valve of all indoor units in accordance with the PID control method, and for each indoor unit, determine whether the temperature of the indoor cabinet is greater than the set temperature. If the temperature of the indoor cabinet is greater than the set temperature, the minimum opening limit of the electronic expansion valve corresponding to the indoor cabinet is set to 55%; if the temperature of the indoor cabinet is less than or equal to the set temperature, the minimum opening limit of the electronic expansion valve corresponding to the indoor cabinet is set to 45%.

[0090] Step 4: when the operation time of the compressor at the oil return frequency exceeds a second defined threshold, exit the oil return mode.

[0091] Since the processing and functions implemented by the device of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0092] According to the technical solution of the present invention, the refrigeration system includes a plurality of evaporators arranged in parallel, each evaporator is provided with a throttling component on the branch, and the evaporators are used to cool different internal cabinets; when the system is running, it is determined whether to turn on the oil return mode according to the operating frequency of the compressor. If it is determined to turn on the oil return mode, the operating frequency of the compressor is controlled to be the oil return frequency, the operating state of the internal cabinet is controlled, and then the minimum opening value of the throttling component is controlled according to the temperature in the internal cabinet. By controlling the operating state of the internal cabinet and the minimum opening value of the throttling component during oil return, the refrigeration oil in all evaporators is removed, the oil return amount of the compressor and the refrigeration effect of the evaporator are increased, and the stable and reliable operation of the system is ensured.

[0093] According to an embodiment of the present invention, a refrigeration system corresponding to the oil return control device of the refrigeration system is also provided. The refrigeration system may include: the oil return control device of the refrigeration system described above.

[0094] Since the processing and functions implemented by the refrigeration system of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned devices, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0095] According to the technical solution of the present invention, the refrigeration system includes a plurality of evaporators arranged in parallel, each evaporator is provided with a throttling component on the branch, and the evaporators are used to cool different internal cabinets; when the system is running, it is determined whether to turn on the oil return mode according to the operating frequency of the compressor. If it is determined to turn on the oil return mode, the operating frequency of the compressor is controlled to be the oil return frequency, the operating state of the internal cabinet is controlled, and then the minimum opening value of the throttling component is controlled according to the temperature in the internal cabinet. By controlling the operating state of the internal cabinet and the minimum opening value of the throttling component during oil return, the refrigeration oil in all evaporators is removed, the oil return amount of the compressor and the refrigeration effect of the evaporator are increased, and the stable and reliable operation of the system is ensured.

[0096] According to an embodiment of the present invention, a storage medium corresponding to the oil return control method of the refrigeration system is also provided, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the oil return control method of the refrigeration system described above.

[0097] Since the processing and functions implemented by the storage medium of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0098] According to the technical solution of the present invention, the refrigeration system includes a plurality of evaporators arranged in parallel, each evaporator is provided with a throttling component on the branch, and the evaporators are used to cool different internal cabinets; when the system is running, it is determined whether to turn on the oil return mode according to the operating frequency of the compressor. If it is determined to turn on the oil return mode, the operating frequency of the compressor is controlled to be the oil return frequency, the operating state of the internal cabinet is controlled, and then the minimum opening value of the throttling component is controlled according to the temperature in the internal cabinet. By controlling the operating state of the internal cabinet and the minimum opening value of the throttling component during oil return, the refrigeration oil in all evaporators is removed, the oil return amount of the compressor and the refrigeration effect of the evaporator are increased, and the stable and reliable operation of the system is ensured.

[0099] According to an embodiment of the present invention, a computer program product corresponding to the oil return control method of a refrigeration system is also provided. The computer program product includes a computer program, and when the computer program product is processed and executed, the steps of the oil return control method of the refrigeration system are implemented.

[0100] Since the processing and functions implemented by the computer program product of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0101] According to the technical solution of the present invention, the refrigeration system includes a plurality of evaporators arranged in parallel, each evaporator is provided with a throttling component on the branch, and the evaporators are used to cool different internal cabinets; when the system is running, it is determined whether to turn on the oil return mode according to the operating frequency of the compressor. If it is determined to turn on the oil return mode, the operating frequency of the compressor is controlled to be the oil return frequency, the operating state of the internal cabinet is controlled, and then the minimum opening value of the throttling component is controlled according to the temperature in the internal cabinet. By controlling the operating state of the internal cabinet and the minimum opening value of the throttling component during oil return, the refrigeration oil in all evaporators is removed, the oil return amount of the compressor and the refrigeration effect of the evaporator are increased, and the stable and reliable operation of the system is ensured.

[0102] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0103] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A method for controlling oil return in a refrigeration system, characterized in that: The refrigeration system comprises: a compressor and at least two evaporators; the evaporators are arranged in parallel, and a throttling component is arranged on the branch where each evaporator is located; each evaporator is used to cool different internal cabinets; The method comprises: Obtaining the operating frequency of the compressor and the temperature inside the inner cabinet; Determining whether to start a preset oil return mode according to the operating frequency of the compressor; If it is determined to start the preset oil return mode, the operating frequency of the compressor is controlled to be the preset oil return frequency; The operating state of the inner cabinet is controlled, and then the minimum opening value of the throttling component is controlled according to the temperature in the inner cabinet.

2. The oil return control method for a refrigeration system according to claim 1, characterized in that: Determining whether to start a preset oil return mode according to the operating frequency of the compressor includes: Determining whether the operating frequency of the compressor is less than or equal to a preset operating frequency; If the operating frequency of the compressor is less than or equal to the preset operating frequency and the preset time has accumulated, determining to start the preset oil return mode; If the operating frequency of the compressor is greater than the preset operating frequency, it is determined not to start the preset oil return mode.

3. The oil return control method for a refrigeration system according to claim 1, characterized in that: The state of the inner cabinet includes a refrigeration on state and a refrigeration off state; Controlling the operating state of the inner cabinet includes: Determine whether there is an inner cabinet whose operating state is the refrigeration shutdown state among all the inner cabinets; If there is an inner cabinet whose operating state is the refrigeration shutdown state, the operating state of the inner cabinet whose operating state is the refrigeration shutdown state is switched to the refrigeration startup state.

4. The oil return control method for a refrigeration system according to claim 1 or 3, characterized in that: Controlling the minimum opening value of the throttling component according to the temperature in the inner cabinet includes: Determining the relationship between the temperature in the inner cabinet and a preset temperature; If the temperature in the inner cabinet is greater than the preset temperature, the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located is controlled to be a preset first opening; If the temperature in the inner cabinet is less than or equal to the preset temperature, the minimum opening value of the throttling component on the branch where the evaporator for cooling the inner cabinet is located is controlled to be a preset second opening; the preset first opening>the preset second opening.

5. The oil return control method for a refrigeration system according to any one of claims 1 to 4, characterized in that: Also includes: When the continuous operation time in the preset oil return mode is greater than the preset time, the preset oil return mode is exited.

6. An oil return control device for a refrigeration system, characterized in that: The refrigeration system comprises: a compressor and at least two evaporators; the evaporators are arranged in parallel, and a throttling component is arranged on the branch where each evaporator is located; each evaporator is used to cool different internal cabinets; The device comprises: an acquisition unit configured to acquire the operating frequency of the compressor and the temperature in the inner cabinet; A control unit, configured to determine whether to start a preset oil return mode according to the operating frequency of the compressor; The control unit is further configured to control the operating frequency of the compressor to a preset oil return frequency if it is determined to start the preset oil return mode; The control unit is further configured to control the operating state of the inner cabinet, and then control the minimum opening value of the throttling component according to the temperature in the inner cabinet.

7. The oil return control device for a refrigeration system according to claim 6, characterized in that: The control unit determines whether to start a preset oil return mode according to the operating frequency of the compressor, including: Determining whether the operating frequency of the compressor is less than or equal to a preset operating frequency; If the operating frequency of the compressor is less than or equal to the preset operating frequency and the preset time has accumulated, determining to start the preset oil return mode; If the operating frequency of the compressor is greater than the preset operating frequency, it is determined not to start the preset oil return mode.

8. A refrigeration system, characterized in that: include: An oil return control device for a refrigeration system as claimed in claim 6 or 7.

9. A display cabinet, characterized in that: Comprising the refrigeration system as claimed in claim 8.

10. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the oil return control method for the refrigeration system according to any one of claims 1 to 5.

11. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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