Oil return control method and device and refrigerating unit

Abstract

The invention discloses an oil return control method and device and a refrigerating unit, and the oil return control method comprises the steps that whether an oil level switch of the refrigerating unit is switched on or not is monitored; and when the oil level switch is not switched on, entering an oil return quantity adjusting mode, and sequentially adjusting the air suction superheat degree, the operation pressure difference, the cooling water temperature and the operation load of the refrigerating unit so as to adjust the oil return quantity of the refrigerating unit. By means of the oil return device, it can be guaranteed that the refrigerating unit can return oil in time under various working conditions, meanwhile, the influence on the temperature of the tail end evaporator is minimum, and the refrigerating effect is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, and more specifically, to an oil return control method, device, and refrigeration unit. Background Technology

[0002] Parallel refrigeration units are commonly used in large cold storage facilities, employing multiple compressors to cool multiple warehouses. Due to variations in the refrigeration load, the number of compressors starting and stopping also changes; the operation of some compressors in a parallel refrigeration unit is referred to as partial load operation.

[0003] Large cold storage refrigeration units rarely operate at full load and are mostly in partial load operation. In addition, due to factors such as outdoor ambient temperature, the refrigeration units often need to operate under low load, low pressure difference and low water temperature. Under these conditions, the refrigeration units are prone to abnormal oil return problems.

[0004] There is currently no effective solution to the problem that refrigerant flow rate is low and oil return is prone to occur when refrigeration units operate under low load, low pressure difference and low water temperature for a long time. Summary of the Invention

[0005] This invention provides an oil return control method, device, and refrigeration unit to solve the problem in the prior art where the refrigerant flow rate is low and abnormal oil return is easily caused when the refrigeration unit operates under low load, low pressure difference, and low water temperature for a long time.

[0006] To solve the above-mentioned technical problems, the present invention provides an oil return control method applied to a refrigeration unit, the oil return control method comprising:

[0007] Monitor whether the oil level switch of the refrigeration unit is connected;

[0008] When the oil level switch is not turned on, the oil return volume adjustment mode is entered, and the suction superheat, operating pressure difference, cooling water temperature and operating load of the refrigeration unit are adjusted in sequence to adjust the oil return volume of the refrigeration unit.

[0009] Further, the suction superheat, operating pressure difference, cooling water temperature, and operating load of the refrigeration unit are adjusted sequentially to regulate the oil return rate of the refrigeration unit, including:

[0010] Adjust the suction superheat of the refrigeration unit;

[0011] Next, determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the operating pressure difference of the refrigeration unit.

[0012] Next, determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the cooling water temperature of the refrigeration unit.

[0013] Then determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the operating load of the refrigeration unit.

[0014] Further, adjusting the suction superheat of the refrigeration unit includes:

[0015] Determine whether the intake superheat is less than or equal to a first preset threshold;

[0016] If so, the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit is reduced;

[0017] Reacquire the intake superheat;

[0018] If the intake superheat is greater than the first preset threshold and less than or equal to the sum of the first preset threshold and the first preset deviation, then the electronic expansion valve is controlled to maintain its current opening.

[0019] If the intake superheat is greater than the sum of the first preset threshold and the first preset deviation, then the intake superheat of the refrigeration unit is stopped.

[0020] Further, adjusting the operating pressure difference of the refrigeration unit includes:

[0021] Determine whether the operating pressure difference is less than or equal to a second preset threshold;

[0022] If so, the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit is reduced;

[0023] Reacquire the operating differential pressure;

[0024] If the operating pressure difference is greater than the second preset threshold and less than or equal to the sum of the second preset threshold and the second preset deviation, then the electronic expansion valve is controlled to maintain its current opening.

[0025] If the operating pressure difference is greater than the sum of the second preset threshold and the second preset deviation, then the adjustment of the operating pressure difference is stopped.

[0026] Further, adjusting the cooling water temperature of the refrigeration unit includes:

[0027] Determine whether the cooling water temperature is less than or equal to a third preset threshold;

[0028] If so, the opening degree of the cooling water regulating valve of the refrigeration unit is reduced;

[0029] The cooling water temperature is retrieved again;

[0030] If the cooling water temperature is greater than the third preset threshold and less than or equal to the sum of the third preset threshold and the third preset deviation, then the cooling water regulating valve is controlled to maintain its current opening.

[0031] If the cooling water temperature is greater than the sum of the third preset threshold and the third preset deviation, then the adjustment of the cooling water temperature will stop.

[0032] Further, adjusting the operating load of the refrigeration unit includes:

[0033] Determine whether the operating load of the refrigeration unit exceeds the fourth preset threshold;

[0034] If so, the opening of the compressor's loading solenoid valve is increased by the first preset step size;

[0035] If not, the opening of the compressor's loading solenoid valve is increased by a second preset step size; wherein the second preset step size is greater than the first preset step size.

[0036] The present invention also provides an oil return control device for use in refrigeration units, the oil return control device comprising:

[0037] The monitoring module is used to monitor whether the oil level switch of the refrigeration unit is connected;

[0038] The control module is used to enter the oil return volume adjustment mode when the oil level switch is not turned on, and sequentially adjust the suction superheat, operating pressure difference, cooling water temperature and operating load of the refrigeration unit to adjust the oil return volume of the refrigeration unit.

[0039] The present invention also provides a refrigeration unit, including the oil return control device of the above embodiments.

[0040] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described oil return control method.

[0041] The present invention also provides an electronic device, comprising:

[0042] One or more processors;

[0043] A storage device for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to implement the above-described oil return control method.

[0044] By applying the technical solution of this invention, firstly, by monitoring whether the oil level switch of the refrigeration unit is connected, it is accurately determined whether the refrigeration unit is short of oil. Secondly, when the refrigeration unit is short of oil, the suction superheat, operating pressure difference, cooling water temperature, and operating load of the refrigeration unit are adjusted sequentially to increase the refrigerant flow rate, thereby regulating the oil return of the refrigeration unit. This ensures that the refrigeration unit can return oil in a timely manner under various operating conditions, keeping the refrigeration system with sufficient oil and avoiding the refrigeration system from being in a state of oil shortage for a long time. This solves the problem that the refrigerant flow rate is low and easily leads to abnormal oil return when the refrigeration unit is running under low load, low pressure difference, and low water temperature for a long time, thus improving the stability of the refrigeration system. In addition, according to the preset priority, parameters with less impact on the temperature of the terminal evaporator are adjusted first, followed by parameters with greater impact on the temperature of the terminal evaporator. This ensures that the refrigeration unit can return oil in a timely manner under various operating conditions while minimizing the impact on the temperature of the terminal evaporator, thus ensuring the refrigeration effect. Attached Figure Description

[0045] Figure 1 The diagram shows the structure of a refrigeration unit according to an embodiment of the present invention; wherein, 1: first compressor, 2: second compressor, 3: oil separator, 4: condenser, 5: terminal evaporator, 6: fan, 7: oil level switch, EXV1: electronic expansion valve, V1: solenoid valve, 8: suction bypass pipeline, V2: bypass solenoid valve.

[0046] Figure 2 This is a flowchart of the oil return control method according to an embodiment of the present invention;

[0047] Figure 3 A flowchart of a return oil control method according to another embodiment of the present invention;

[0048] Figure 4 This is a structural block diagram of the oil return control device according to an embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0051] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0052] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0053] It should be understood that although the terms first, second, third, etc., may be used to describe preset thresholds in the embodiments of the present invention, these preset thresholds should not be limited to these terms. These terms are only used to distinguish different preset thresholds. For example, without departing from the scope of the embodiments of the present invention, the first preset threshold may also be referred to as the second preset threshold, and similarly, the second preset threshold may also be referred to as the first preset threshold.

[0054] Depending on the context, the words “if” or “suppose” as used here can be interpreted as “when” or “in response to determination” or “in response to detection.” Similarly, depending on the context, the phrases “if determination” or “if detection (of the stated condition or event)” can be interpreted as “when determination” or “in response to determination” or “when detection (of the stated condition or event)” or “in response to detection (of the stated condition or event).”

[0055] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0056] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0057] Example 1

[0058] Parallel refrigeration units are commonly used in large cold storage facilities, employing multiple compressors to cool multiple warehouses. Due to variations in the refrigeration load, the number of compressors starting and stopping also changes; the operation of some compressors in a parallel refrigeration unit is referred to as partial load operation.

[0059] Large cold storage refrigeration units rarely operate at full load and are mostly in partial load operation. In addition, due to factors such as outdoor ambient temperature, the refrigeration units often need to operate under low load, low pressure difference and low water temperature. Under these conditions, the refrigeration units are prone to abnormal oil return problems.

[0060] To address the problem in existing technologies where refrigerant flow rates are low and prone to abnormal oil return when refrigeration units operate under low load, low pressure differential, and low water temperature for extended periods, this embodiment provides an oil return control method applicable to refrigeration units. Figure 1 A structural diagram of a refrigeration unit according to an embodiment of the present invention is shown below. Figure 1 As shown, the refrigeration system includes a first compressor 1, a second compressor 2, an oil separator 3, a condenser 4, a terminal evaporator 5, and a fan 6. An oil level switch 7 is installed on the oil separator 3. When the refrigeration unit has sufficient oil, the oil level switch 7 is closed; when the refrigeration unit is short of oil, the oil level switch 7 is open. An electronic expansion valve EXV1 and a solenoid valve V1 are installed between the condenser 4 and the terminal evaporator 5. An inlet water pipe 41 and an outlet water pipe 41 are installed on the condenser 4. A cooling water regulating valve V3 is installed on the inlet water pipe 41.

[0061] A suction bypass pipe 8 is provided between the suction end of the compressor 1 and the second compressor 2 and the terminal evaporator 5, and a suction bypass solenoid valve V2 is provided on the suction bypass pipe 8.

[0062] Figure 2 A flowchart of the oil return control method according to an embodiment of the present invention is shown below. Figure 2 As shown, the oil return control method includes:

[0063] S101, monitor whether the oil level switch of the refrigeration unit is connected.

[0064] The oil level switch 7 is located on the oil separator. When the oil level switch 7 is turned on, it indicates that the refrigeration unit has sufficient oil. When the oil level switch 7 is turned off, it indicates that the refrigeration unit is short of oil.

[0065] S102, when the oil level switch is not turned on, enters the oil return volume adjustment mode, and sequentially adjusts the suction superheat of the refrigeration unit, the operating pressure difference, the cooling water temperature and the operating load to adjust the oil return volume of the refrigeration unit.

[0066] The operating parameters of the refrigeration unit include suction superheat, operating differential pressure, cooling water temperature, and operating load. Among these, adjusting the operating load has the greatest impact on the temperature of the terminal evaporator, followed by the cooling water temperature, then the operating differential pressure, while adjusting the suction superheat has the least impact. To ensure that the impact of the oil return process on the temperature of the terminal evaporator is minimized, the adjustment priority of the above parameters is as follows: suction superheat > operating differential pressure > cooling water temperature > and operating load.

[0067] The oil return control method in this embodiment firstly determines whether the refrigeration unit is short of oil by monitoring whether the oil level switch of the refrigeration unit is on. Secondly, when the refrigeration unit is short of oil, the suction superheat, operating pressure difference, cooling water temperature, and operating load of the refrigeration unit are adjusted sequentially to increase the refrigerant flow rate, thereby regulating the oil return amount of the refrigeration unit. This ensures that the refrigeration unit can return oil in a timely manner under various operating conditions, keeping the refrigeration system with sufficient oil and avoiding the refrigeration system from being in a state of oil shortage for a long time. This solves the problem that the refrigerant flow rate is low and easily leads to abnormal oil return when the refrigeration unit is running under low load, low pressure difference, and low water temperature for a long time, thus improving the stability of the refrigeration system. In addition, according to the preset priority, parameters with less impact on the temperature of the terminal evaporator are adjusted first, and parameters with greater impact on the temperature of the terminal evaporator are adjusted later. This ensures that the refrigeration unit can return oil in a timely manner under various operating conditions while minimizing the impact on the temperature of the terminal evaporator, thus ensuring the refrigeration effect.

[0068] After each adjustment of operating parameters, the oil return volume may change. If the oil return volume meets expectations, there is no need to adjust the next operating parameter; if the oil return volume does not meet expectations, the next operating parameter needs to be adjusted. Therefore, to ensure that the oil return volume meets expectations, the suction superheat, operating differential pressure, cooling water temperature, and operating load of the refrigeration unit are adjusted sequentially to regulate the oil return volume of the refrigeration unit. This includes: adjusting the suction superheat of the refrigeration unit; then checking if the oil level switch is on; if yes, exiting the oil return volume adjustment mode; if no, adjusting the operating differential pressure of the refrigeration unit; then checking if the oil level switch is on; if yes, exiting the oil return volume adjustment mode; if no, adjusting the cooling water temperature of the refrigeration unit; then checking if the oil level switch is on; if yes, exiting the oil return volume adjustment mode; if no, adjusting the operating load of the refrigeration unit.

[0069] To achieve precise adjustment of the suction superheat and minimize its impact on the cooling effect, the suction superheat of the refrigeration unit is adjusted by: determining whether the suction superheat is less than or equal to a first preset threshold; if so, reducing the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit; re-acquiring the suction superheat; if the suction superheat is greater than the first preset threshold and less than or equal to the sum of the first preset threshold and the first preset deviation, maintaining the current opening of the electronic expansion valve; if the suction superheat is greater than the sum of the first preset threshold and the first preset deviation, stopping the suction superheat of the refrigeration unit.

[0070] If the suction superheat is less than or equal to the first preset threshold, it indicates that the suction superheat is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, it is necessary to reduce the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit to increase the suction superheat. To avoid significantly affecting the refrigeration effect, the increase in suction superheat needs to be within a certain range. Therefore, after reducing the opening of the electronic expansion valve between the condenser and evaporator, it is necessary to re-acquire the suction superheat. If the suction superheat is greater than the first preset threshold and less than or equal to the sum of the first preset threshold and the first preset deviation, it indicates that the adjustment of the suction superheat has not exceeded the necessary limit, and the electronic expansion valve can be controlled to maintain the current opening. If the suction superheat is greater than the sum of the first preset threshold and the first preset deviation, it indicates that the adjustment of the suction superheat has been excessive, and the suction superheat of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0071] To achieve precise adjustment of the operating pressure difference and minimize its impact on the cooling effect, the adjustment of the operating pressure difference of the refrigeration unit includes: determining whether the operating pressure difference is less than or equal to a second preset threshold; if so, reducing the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit; re-acquiring the operating pressure difference; if the operating pressure difference is greater than the second preset threshold and less than or equal to the sum of the second preset threshold and the second preset deviation, maintaining the current opening of the electronic expansion valve; if the operating pressure difference is greater than the sum of the second preset threshold and the second preset deviation, stopping the adjustment of the operating pressure difference.

[0072] If the operating differential pressure is less than or equal to the second preset threshold, it indicates that the operating differential pressure is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, it is necessary to reduce the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit to increase the operating differential pressure. To avoid significantly affecting the refrigeration effect, the increase in operating differential pressure needs to be within a certain range. Therefore, after reducing the opening of the electronic expansion valve between the condenser and evaporator, it is necessary to re-acquire the operating differential pressure. If the operating differential pressure is greater than the second preset threshold and less than or equal to the sum of the second preset threshold and the second preset deviation, it indicates that the adjustment of the operating differential pressure has not exceeded the necessary limit, and the electronic expansion valve can be controlled to maintain the current opening. If the operating differential pressure is greater than the sum of the second preset threshold and the second preset deviation, it indicates that the adjustment of the operating differential pressure has been excessive, and the operating differential pressure of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0073] To achieve precise regulation of the cooling water temperature and minimize its impact on the cooling effect, the cooling water temperature of the refrigeration unit is regulated by: determining whether the cooling water temperature is less than or equal to a third preset threshold; if so, reducing the opening of the cooling water regulating valve of the refrigeration unit; re-acquiring the cooling water temperature; if the cooling water temperature is greater than the third preset threshold and less than or equal to the sum of the third preset threshold and the third preset deviation, maintaining the current opening of the cooling water regulating valve; if the cooling water temperature is greater than the sum of the third preset threshold and the third preset deviation, stopping the regulation of the cooling water temperature.

[0074] If the cooling water temperature is less than or equal to the third preset threshold, it indicates that the cooling water temperature is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, the opening of the cooling water regulating valve on the condenser inlet pipe needs to be reduced to increase the cooling water temperature. To avoid significantly affecting the cooling effect, the increase in cooling water temperature needs to be within a certain range. Therefore, after reducing the opening of the cooling water regulating valve on the condenser inlet pipe, the cooling water temperature needs to be re-acquired. If the cooling water temperature is greater than the third preset threshold and less than or equal to the sum of the third preset threshold and the third preset deviation, it indicates that the adjustment of the cooling water temperature has not exceeded the necessary limit, and the cooling water regulating valve can be controlled to maintain the current opening. If the cooling water temperature is greater than the sum of the third preset threshold and the third preset deviation, it indicates that the adjustment of the cooling water temperature has been excessive, and the cooling water temperature of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0075] After adjusting the above operating parameters without achieving the desired oil return volume, in order to achieve rapid oil return and ensure the normal operation of the cooling unit, the operating load of the refrigeration unit must be adjusted. Adjusting the operating load of the refrigeration unit specifically includes: determining whether the operating load of the refrigeration unit exceeds a fourth preset threshold; if so, increasing the opening of the compressor's loading solenoid valve by a first preset step size to adjust the oil return volume through slow loading; if not, increasing the opening of the compressor's loading solenoid valve by a second preset step size; wherein the second preset step size is greater than the first preset step size, adjusting the oil return volume through rapid loading. After entering rapid loading, the suction bypass solenoid valve V2 reopens.

[0076] Since adjusting the operating load has a significant impact on the temperature of the terminal evaporator of the refrigeration system, and thus a significant impact on the refrigeration effect, in order to minimize the impact on the refrigeration effect, if the operating load of the refrigeration unit is large, a smaller adjustment step size should be used to increase the opening of the compressor loading solenoid valve and slowly adjust the compressor load. If the operating load of the refrigeration unit is small, and the desired oil return amount is not achieved by slowly adjusting the compressor load, the adjustment step size should be increased to increase the opening of the compressor loading solenoid valve and quickly adjust the compressor load, thereby enabling the oil return amount to reach the desired value quickly and shortening the oil return time.

[0077] This embodiment intelligently determines whether the unit has abnormal oil return under various harsh conditions and the cause of such abnormalities by detecting suction superheat, operating pressure difference, and cooling water temperature under different operating conditions. It then makes targeted intelligent adjustments to address the oil return abnormalities caused by different conditions. This solves the oil return problem of the refrigeration unit under various harsh conditions, enabling the unit to operate safely and reliably under different operating conditions.

[0078] Example 2

[0079] This embodiment provides another method for controlling oil return. Figure 3 A flowchart of a return oil control method according to another embodiment of the present invention is shown below. Figure 3 As shown, the oil return control method includes:

[0080] S31 controls the refrigeration unit to start operating.

[0081] S32, determine whether the oil level switch is on; if yes, proceed to step S33; if no, proceed to step S34.

[0082] S33 controls the refrigeration unit to continue operating according to the current state.

[0083] S34 detects various operating parameters of the refrigeration unit.

[0084] S35 adjusts the oil return volume by regulating the intake superheat.

[0085] The oil return volume is adjusted by regulating the intake superheat. The specific control process is as follows:

[0086] If the intake superheat is less than or equal to the first preset threshold Ta, the opening of the electronic expansion valve EXV between the condenser and the terminal evaporator is reduced; then the intake superheat is reacquired; if the first preset threshold Ta is less than or equal to the first preset threshold Ta + 5°C, the opening of the electronic expansion valve EXV remains unchanged; if the intake superheat is greater than the first preset threshold Ta + 5°C, the adjustment of the return oil volume by adjusting the intake superheat is stopped.

[0087] If the suction superheat is less than or equal to the first preset threshold, it indicates that the suction superheat is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, it is necessary to reduce the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit to increase the suction superheat. To avoid significantly affecting the refrigeration effect, the increase in suction superheat needs to be within a certain range. Therefore, after reducing the opening of the electronic expansion valve between the condenser and evaporator, it is necessary to re-acquire the suction superheat. If the suction superheat is greater than the first preset threshold and less than or equal to the sum of the first preset threshold and the first preset deviation, it indicates that the adjustment of the suction superheat has not exceeded the necessary limit, and the electronic expansion valve can be controlled to maintain the current opening. If the suction superheat is greater than the sum of the first preset threshold and the first preset deviation, it indicates that the adjustment of the suction superheat has been excessive, and the suction superheat of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0088] S36, determine whether the oil level switch is on; if yes, proceed to step S33; if no, proceed to step S37.

[0089] S37 adjusts the return oil volume by regulating the operating pressure difference.

[0090] The return oil volume is adjusted by operating differential pressure. The specific control process is as follows:

[0091] If the operating pressure difference is less than or equal to the second preset threshold P, the opening of the electronic expansion valve EXV between the condenser and the terminal evaporator is reduced; then the operating pressure difference is reacquired; if the second preset threshold P < operating pressure difference ≤ second preset threshold P + 30 kPa, the opening of the electronic expansion valve EXV remains unchanged; if the suction superheat operating pressure difference is greater than the second preset threshold P + 30 kPa, the adjustment of the return oil volume by the operating pressure difference is stopped.

[0092] If the operating differential pressure is less than or equal to the second preset threshold, it indicates that the operating differential pressure is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, it is necessary to reduce the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit to increase the operating differential pressure. To avoid significantly affecting the refrigeration effect, the increase in operating differential pressure needs to be within a certain range. Therefore, after reducing the opening of the electronic expansion valve between the condenser and evaporator, it is necessary to re-acquire the operating differential pressure. If the operating differential pressure is greater than the second preset threshold and less than or equal to the sum of the second preset threshold and the second preset deviation, it indicates that the adjustment of the operating differential pressure has not exceeded the necessary limit, and the electronic expansion valve can be controlled to maintain the current opening. If the operating differential pressure is greater than the sum of the second preset threshold and the second preset deviation, it indicates that the adjustment of the operating differential pressure has been excessive, and the operating differential pressure of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0093] S38, determine whether the oil level switch is on; if yes, proceed to step S33; if no, proceed to step S39.

[0094] S39 regulates the oil return volume by adjusting the cooling water temperature.

[0095] The oil return rate is adjusted by regulating the cooling water temperature. The specific control process is as follows:

[0096] If the cooling water temperature is ≤ Tb, the opening of the cooling water regulating valve on the cooling water inlet pipe of the condenser is reduced; then the cooling water temperature is re-acquired; if Tb < cooling water temperature Tb1 ≤ Tb + 5℃, the opening of the cooling water regulating valve remains unchanged; if the cooling water temperature > Tb + 5℃, the oil return rate is stopped from being regulated by the cooling water temperature.

[0097] If the cooling water temperature is less than or equal to the third preset threshold, it indicates that the cooling water temperature is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, the opening of the cooling water regulating valve on the condenser inlet pipe needs to be reduced to increase the cooling water temperature. To avoid significantly affecting the cooling effect, the increase in cooling water temperature needs to be within a certain range. Therefore, after reducing the opening of the cooling water regulating valve on the condenser inlet pipe, the cooling water temperature needs to be re-acquired. If the cooling water temperature is greater than the third preset threshold and less than or equal to the sum of the third preset threshold and the third preset deviation, it indicates that the adjustment of the cooling water temperature has not exceeded the necessary limit, and the cooling water regulating valve can be controlled to maintain the current opening. If the cooling water temperature is greater than the sum of the third preset threshold and the third preset deviation, it indicates that the adjustment of the cooling water temperature has been excessive, and the cooling water temperature of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0098] S310, determine whether the oil level switch is on; if yes, proceed to step S33; if no, proceed to step S311.

[0099] S311, determine whether the operating load > fourth preset threshold Q is true; if yes, proceed to step S312; if no, proceed to step S313.

[0100] S312, slow loading controls the return oil volume.

[0101] S313, quick loading control of oil return volume.

[0102] After adjusting the above operating parameters without achieving the desired oil return volume, in order to achieve rapid oil return and ensure the normal operation of the cooling unit, the operating load of the refrigeration unit must be adjusted. Adjusting the operating load of the refrigeration unit specifically includes: determining whether the operating load of the refrigeration unit exceeds a fourth preset threshold; if so, increasing the opening of the compressor's loading solenoid valve by a first preset step size to control the oil return volume through slow loading; if not, increasing the opening of the compressor's loading solenoid valve by a second preset step size, where the second preset step size is larger than the first preset step size, to control the oil return volume through rapid loading. After entering rapid loading, the suction bypass solenoid valve V2 reopens.

[0103] Example 3

[0104] This embodiment provides an oil return control device applied to a refrigeration unit. Figure 4 This is a structural block diagram of the oil return control device according to an embodiment of the present invention, such as... Figure 4 As shown, the oil return control device includes:

[0105] Monitoring module 401 is used to monitor whether the oil level switch of the refrigeration unit is connected.

[0106] The monitoring module 401 is connected to the oil level switch 7, which is located on the oil separator. When the oil level switch 7 is turned on, it indicates that the refrigeration unit has sufficient oil. When the oil level switch 7 is turned off, it indicates that the refrigeration unit is short of oil.

[0107] The control module 402 is used to enter the oil return volume adjustment mode when the oil level switch is not turned on, and sequentially adjust the suction superheat, operating pressure difference, cooling water temperature and operating load of the refrigeration unit to adjust the oil return volume of the refrigeration unit.

[0108] The operating parameters of the refrigeration unit include suction superheat, operating differential pressure, cooling water temperature, and operating load. Among these, adjusting the operating load has the greatest impact on the temperature of the terminal evaporator, followed by the cooling water temperature, then the operating differential pressure, while adjusting the suction superheat has the least impact. To ensure that the impact of the oil return process on the temperature of the terminal evaporator is minimized, the adjustment priority of the above parameters is as follows: suction superheat > operating differential pressure > cooling water temperature > and operating load.

[0109] The oil return control device in this embodiment first monitors whether the oil level switch of the refrigeration unit is on to accurately determine whether the refrigeration unit is short of oil. Secondly, when the refrigeration unit is short of oil, the control module 402 sequentially adjusts the suction superheat, operating pressure difference, cooling water temperature, and operating load of the refrigeration unit to increase the refrigerant flow rate, thereby regulating the oil return amount. This ensures timely oil return under various operating conditions, maintaining sufficient oil in the refrigeration system and preventing it from being in a state of oil shortage for extended periods. It also solves the problem of low refrigerant flow rate and abnormal oil return when the refrigeration unit operates under low load, low pressure difference, and low water temperature for extended periods, thus improving the stability of the refrigeration system. Furthermore, according to a pre-set priority, parameters with less impact on the terminal evaporator temperature are adjusted first, followed by parameters with greater impact. This ensures timely oil return under various operating conditions while minimizing the impact on the terminal evaporator temperature, guaranteeing the cooling effect.

[0110] After each adjustment of operating parameters, the oil return volume may change. If the oil return volume meets expectations, there is no need to adjust the next operating parameter; if the oil return volume does not meet expectations, the next operating parameter needs to be adjusted. Therefore, to ensure that the oil return volume meets expectations, the control module 402 performs the following operations when adjusting the suction superheat, operating differential pressure, cooling water temperature, and operating load of the refrigeration unit in sequence to regulate the oil return volume of the refrigeration unit: Adjust the suction superheat of the refrigeration unit; then determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the operating differential pressure of the refrigeration unit; then determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the cooling water temperature of the refrigeration unit; then determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the operating load of the refrigeration unit.

[0111] To achieve precise adjustment of the suction superheat and minimize its impact on the cooling effect, the control module 402 performs the following operations when adjusting the suction superheat of the refrigeration unit: It determines whether the suction superheat is less than or equal to a first preset threshold; if so, it controls the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit to decrease; it re-acquires the suction superheat; if the suction superheat is greater than the first preset threshold and less than or equal to the sum of the first preset threshold and the first preset deviation, it controls the electronic expansion valve to maintain its current opening; if the suction superheat is greater than the sum of the first preset threshold and the first preset deviation, it stops adjusting the suction superheat of the refrigeration unit.

[0112] If the suction superheat is less than or equal to the first preset threshold, it indicates that the suction superheat is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, it is necessary to reduce the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit to increase the suction superheat. To avoid significantly affecting the refrigeration effect, the increase in suction superheat needs to be within a certain range. Therefore, after reducing the opening of the electronic expansion valve between the condenser and evaporator, it is necessary to re-acquire the suction superheat. If the suction superheat is greater than the first preset threshold and less than or equal to the sum of the first preset threshold and the first preset deviation, it indicates that the adjustment of the suction superheat has not exceeded the necessary limit, and the electronic expansion valve can be controlled to maintain the current opening. If the suction superheat is greater than the sum of the first preset threshold and the first preset deviation, it indicates that the adjustment of the suction superheat has been excessive, and the suction superheat of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0113] To achieve precise adjustment of the operating pressure difference and minimize the impact on the cooling effect, the control module 402 performs the following operations when adjusting the operating pressure difference of the refrigeration unit: It determines whether the operating pressure difference is less than or equal to a second preset threshold; if so, it controls the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit to decrease; it re-acquires the operating pressure difference; if the operating pressure difference is greater than the second preset threshold and less than or equal to the sum of the second preset threshold and the second preset deviation, it controls the electronic expansion valve to maintain its current opening; if the operating pressure difference is greater than the sum of the second preset threshold and the second preset deviation, it stops adjusting the operating pressure difference.

[0114] If the operating differential pressure is less than or equal to the second preset threshold, it indicates that the operating differential pressure is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, it is necessary to reduce the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit to increase the operating differential pressure. To avoid significantly affecting the refrigeration effect, the increase in operating differential pressure needs to be within a certain range. Therefore, after reducing the opening of the electronic expansion valve between the condenser and evaporator, it is necessary to re-acquire the operating differential pressure. If the operating differential pressure is greater than the second preset threshold and less than or equal to the sum of the second preset threshold and the second preset deviation, it indicates that the adjustment of the operating differential pressure has not exceeded the necessary limit, and the electronic expansion valve can be controlled to maintain the current opening. If the operating differential pressure is greater than the sum of the second preset threshold and the second preset deviation, it indicates that the adjustment of the operating differential pressure has been excessive, and the operating differential pressure of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0115] To achieve precise adjustment of the cooling water temperature and minimize the impact on the cooling effect, the control module 402 performs the following operations when adjusting the cooling water temperature of the refrigeration unit: It determines whether the cooling water temperature is less than or equal to a third preset threshold; if so, it controls the opening of the cooling water regulating valve of the refrigeration unit to decrease; it re-acquires the cooling water temperature; if the cooling water temperature is greater than the third preset threshold and less than or equal to the sum of the third preset threshold and the third preset deviation, it controls the cooling water regulating valve to maintain its current opening; if the cooling water temperature is greater than the sum of the third preset threshold and the third preset deviation, it stops adjusting the cooling water temperature.

[0116] If the cooling water temperature is less than or equal to the third preset threshold, it indicates that the cooling water temperature is too low, indirectly reflecting a low refrigerant flow rate and insufficient oil return in the refrigeration system. Therefore, the opening of the cooling water regulating valve on the condenser inlet pipe needs to be reduced to increase the cooling water temperature. To avoid significantly affecting the cooling effect, the increase in cooling water temperature needs to be within a certain range. Therefore, after reducing the opening of the cooling water regulating valve on the condenser inlet pipe, the cooling water temperature needs to be re-acquired. If the cooling water temperature is greater than the third preset threshold and less than or equal to the sum of the third preset threshold and the third preset deviation, it indicates that the adjustment of the cooling water temperature has not exceeded the necessary limit, and the cooling water regulating valve can be controlled to maintain the current opening. If the cooling water temperature is greater than the sum of the third preset threshold and the third preset deviation, it indicates that the adjustment of the cooling water temperature has been excessive, and the cooling water temperature of the refrigeration unit should be stopped, and the next operating parameter should be adjusted.

[0117] After adjusting the above operating parameters without achieving the desired oil return volume, in order to achieve rapid oil return and ensure the normal operation of the cooling unit, the operating load of the refrigeration unit must be adjusted. When adjusting the operating load of the refrigeration unit, the control module 402 performs the following operations: It determines whether the operating load of the refrigeration unit is greater than a fourth preset threshold; if so, it increases the opening of the compressor's loading solenoid valve by a first preset step size, adjusting the oil return volume through slow loading; if not, it increases the opening of the compressor's loading solenoid valve by a second preset step size; wherein the second preset step size is greater than the first preset step size, adjusting the oil return volume through rapid loading. After entering rapid loading, the suction bypass solenoid valve V2 reopens.

[0118] Since adjusting the operating load has a significant impact on the temperature of the terminal evaporator of the refrigeration system, and thus a significant impact on the refrigeration effect, in order to minimize the impact on the refrigeration effect, if the operating load of the refrigeration unit is large, a smaller adjustment step size should be used to increase the opening of the compressor loading solenoid valve and slowly adjust the compressor load. If the operating load of the refrigeration unit is small, and the desired oil return amount is not achieved by slowly adjusting the compressor load, the adjustment step size should be increased to increase the opening of the compressor loading solenoid valve and quickly adjust the compressor load, thereby enabling the oil return amount to reach the desired value quickly and shortening the oil return time.

[0119] Example 4

[0120] This embodiment provides a refrigeration unit, including the oil return control device described in the above embodiment.

[0121] Example 5

[0122] This embodiment provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the oil return control method in the above embodiment.

[0123] Example 6

[0124] This embodiment provides an electronic device, including:

[0125] One or more processors;

[0126] A storage device is provided for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to implement the oil return control method in the above embodiments.

[0127] Figure 5 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention, such as... Figure 5 As shown, the electronic device includes:

[0128] One or more processors 510 and memory 520, Figure 5 Take the 510 processor as an example.

[0129] The aforementioned electronic device may further include: an input device 530 and an output device 540.

[0130] The processor 510, memory 520, input device 530, and output device 540 can be connected via a bus or other means. Figure 5 Taking the example of a connection between China and Israel via a bus.

[0131] The memory 520, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as the program instructions / modules corresponding to the anomaly detection method in this embodiment of the invention. The processor 510 executes various functional applications and data processing of the server by running the non-volatile software programs, instructions, and modules stored in the memory 520, thereby implementing the above-described method embodiments.

[0132] The memory 520 may include a program storage area and a data storage area, wherein the program storage area may store application programs required for operating the device and at least one function; and the data storage area may store data created based on the use of the anomaly detection device, etc. Furthermore, the memory 520 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device.

[0133] Input device 530 can receive input digital or character information, and generate key signal inputs related to user settings and function control of the electronic device. Output device 540 may include display devices such as a display screen.

[0134] The one or more modules are stored in the memory 520, and when executed by the one or more processors 510, they execute the anomaly detection method in any of the above method embodiments.

[0135] The aforementioned electronic device product can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in the embodiments of the present invention.

[0136] The electronic devices of this invention exist in various forms, including but not limited to:

[0137] (1) Mobile communication devices: These devices are characterized by their mobile communication capabilities and are primarily designed to provide voice and data communication. These terminals include smartphones (e.g., iPhones), multimedia phones, feature phones, and low-end phones.

[0138] (2) Ultra-mobile personal computer devices: These devices fall under the category of personal computers, have computing and processing functions, and generally also have mobile internet access capabilities. These terminals include: PDAs, MIDs, and UMPCs, such as iPads.

[0139] (3) Portable entertainment devices: These devices can display and play multimedia content. This category includes: audio and video players (such as iPods), handheld game consoles, e-books, as well as smart toys and portable car navigation devices.

[0140] (4) Server: A device that provides computing services. The components of a server include a processor, hard disk, memory, device bus, etc. Servers are similar to general computer architectures, but because they need to provide highly reliable services, they have higher requirements in terms of processing power, stability, reliability, security, scalability, and manageability.

[0141] (5) Other electronic devices with data interaction functions, such as televisions, in-vehicle screens, etc.

[0142] The device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0143] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the oil return control method described in various embodiments or some parts of embodiments.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling oil return, applied to a refrigeration unit, characterized in that, The oil return control method includes: Monitor whether the oil level switch of the refrigeration unit is connected; When the oil level switch is not turned on, the oil return volume adjustment mode is entered, and the suction superheat, operating pressure difference, cooling water temperature and operating load of the refrigeration unit are adjusted in sequence to adjust the oil return volume of the refrigeration unit.

2. The oil return control method according to claim 1, characterized in that, The oil return rate of the refrigeration unit is adjusted sequentially by regulating the suction superheat, operating pressure difference, cooling water temperature, and operating load, including: Adjust the suction superheat of the refrigeration unit; Next, determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the operating pressure difference of the refrigeration unit. Next, determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the cooling water temperature of the refrigeration unit. Then determine whether the oil level switch is on; if yes, exit the oil return volume adjustment mode; if no, adjust the operating load of the refrigeration unit.

3. The oil return control method according to claim 2, characterized in that, Adjusting the suction superheat of the refrigeration unit includes: Determine whether the intake superheat is less than or equal to a first preset threshold; If so, the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit is reduced; Reacquire the intake superheat; If the intake superheat is greater than the first preset threshold and less than or equal to the sum of the first preset threshold and the first preset deviation, then the electronic expansion valve is controlled to maintain its current opening. If the intake superheat is greater than the sum of the first preset threshold and the first preset deviation, then the intake superheat of the refrigeration unit is stopped.

4. The oil return control method according to claim 2, characterized in that, Adjusting the operating pressure differential of the refrigeration unit includes: Determine whether the operating pressure difference is less than or equal to a second preset threshold; If so, the opening of the electronic expansion valve between the condenser and evaporator of the refrigeration unit is reduced; Reacquire the operating differential pressure; If the operating pressure difference is greater than the second preset threshold and less than or equal to the sum of the second preset threshold and the second preset deviation, then the electronic expansion valve is controlled to maintain its current opening. If the operating pressure difference is greater than the sum of the second preset threshold and the second preset deviation, then the adjustment of the operating pressure difference is stopped.

5. The oil return control method according to claim 2, characterized in that, Adjusting the cooling water temperature of the refrigeration unit includes: Determine whether the cooling water temperature is less than or equal to a third preset threshold; If so, the opening degree of the cooling water regulating valve of the refrigeration unit is reduced; The cooling water temperature is retrieved again; If the cooling water temperature is greater than the third preset threshold and less than or equal to the sum of the third preset threshold and the third preset deviation, then the cooling water regulating valve is controlled to maintain its current opening. If the cooling water temperature is greater than the sum of the third preset threshold and the third preset deviation, then the adjustment of the cooling water temperature will stop.

6. The oil return control method according to claim 2, characterized in that, Adjusting the operating load of the refrigeration unit includes: Determine whether the operating load of the refrigeration unit exceeds the fourth preset threshold; If so, the opening of the compressor's loading solenoid valve is increased by the first preset step size; If not, the opening of the compressor's loading solenoid valve is increased by a second preset step size; wherein the second preset step size is greater than the first preset step size.

7. An oil return control device, applied to a refrigeration unit, characterized in that, The oil return control device includes: The monitoring module is used to monitor whether the oil level switch of the refrigeration unit is connected; The control module is used to enter the oil return volume adjustment mode when the oil level switch is not turned on, and sequentially adjust the suction superheat, operating pressure difference, cooling water temperature and operating load of the refrigeration unit to adjust the oil return volume of the refrigeration unit.

8. A refrigeration unit, characterized in that, Includes the oil return control device as described in claim 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the oil return control method as described in any one of claims 1 to 6.

10. An electronic device, characterized in that, include: One or more processors; A storage device for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to implement the oil return control method as described in any one of claims 1 to 6.

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