A method and device for oil return control, and an air-cooled water chiller unit

Abstract

This invention discloses an oil return control method and device, and an air-cooled water chiller unit. The method includes: monitoring the oil level of the compressor's refrigerant oil; if the oil level is lower than a preset threshold, controlling the compressor to ensure that the intake volume is greater than the discharge volume per unit time. This invention solves the technical problem of low oil return efficiency in existing compressors, achieving rapid oil return without adding extra equipment, and improving the compressor's oil return efficiency while ensuring compressor reliability and without increasing hardware costs.

Description

Technical Field

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

[0002] In existing technologies, compressors need to be equipped with refrigeration oil. For example, in screw-type air-cooled chiller (heater) units that use screw compressors, refrigeration oil has functions such as lubrication, sealing, cooling and energy regulation. It is indispensable in ensuring the performance and reliability of the compressor. The refrigeration oil carried by the refrigerant is discharged into the system after passing through the compressor. Due to the long refrigerant flow of the air system unit, the refrigeration oil does not return to the compressor in time, resulting in oil shortage in the compressor.

[0003] In existing technologies, the above problems can be addressed by adding a refrigerant oil storage device that starts when oil is low, but this method increases the cost. Alternatively, the opening of the electronic expansion valve can be increased to increase the refrigerant flow rate and thus accelerate the return of refrigerant oil to the compressor. However, this method is prone to liquid contamination during air intake, leading to liquid slugging in the compressor and causing new reliability issues.

[0004] There is currently no effective solution to the problem of low oil return efficiency in existing compressor technologies. Summary of the Invention

[0005] This invention provides an oil return control method and device, and an air-cooled water chiller unit, to solve the technical problem of low oil return efficiency in existing compressors.

[0006] To address the aforementioned technical problems, this invention provides an oil return control method, comprising: monitoring the oil level scale of the compressor's refrigeration oil; and if the oil level scale is lower than a preset threshold, controlling the compressor to have a suction volume greater than its discharge volume per unit time.

[0007] Furthermore, controlling the compressor to have a greater intake volume than exhaust volume per unit time includes: continuously energizing the first capacity regulating solenoid valve of the compressor and pulse-energizing the second capacity regulating solenoid valve of the compressor, wherein the load of the first capacity regulating solenoid valve is less than that of the second capacity regulating solenoid valve.

[0008] Furthermore, if the oil level scale is lower than a preset threshold, the method further includes: obtaining the superheat and temperature change rate of the compressor; adjusting the opening of the electronic expansion valve according to the superheat and the temperature change rate, wherein one end of the electronic expansion valve is connected to the exhaust side of the compressor via an air-cooled heat exchanger, and the other end of the electronic expansion valve is connected to the suction side of the compressor via a cold water-side heat exchanger.

[0009] Further, obtaining the superheat and temperature change rate of the compressor includes: collecting the suction temperature and first pressure of the compressor on the suction side, and collecting the discharge temperature and second pressure of the compressor on the discharge side; calculating a first temperature difference between the suction temperature and the saturation temperature corresponding to the first pressure, calculating a second temperature difference between the discharge temperature and the saturation temperature corresponding to the second pressure, calculating a third temperature difference between the suction temperature and a historical suction temperature, and calculating a fourth temperature difference between the discharge temperature and a historical discharge temperature; determining the first temperature difference as the suction superheat, the second temperature difference as the discharge superheat, the third temperature difference as the suction temperature change rate, and the fourth temperature difference as the discharge temperature change rate, wherein the superheat includes the suction superheat or the discharge superheat, and the temperature change rate includes the suction temperature change rate or the discharge temperature change rate.

[0010] Further, adjusting the opening of the electronic expansion valve according to the superheat and the rate of temperature change includes: determining whether the superheat is greater than or equal to a superheat threshold, determining whether the rate of temperature change is greater than or equal to a rate of change threshold, and determining whether the rate of temperature change is greater than or equal to 0; if the superheat is greater than or equal to the superheat threshold, the rate of temperature change is greater than or equal to the rate of change threshold, and the rate of temperature change is greater than or equal to 0, increasing the opening of the electronic expansion valve by a preset step size.

[0011] Furthermore, the method also includes: if the superheat is less than the superheat threshold and the temperature change rate is less than the change rate threshold, reducing the opening of the electronic expansion valve by a preset step size.

[0012] Furthermore, before monitoring the oil level scale of the compressor's refrigeration oil, the method includes: detecting the oil level alarm signal of the compressor; and responding to the oil level alarm signal by activating the oil return mode.

[0013] According to another aspect of the embodiments of this application, an oil return control device is also provided, comprising: a monitoring module for monitoring the oil level scale of the compressor refrigeration oil; and a control module for controlling the compressor to have a suction volume greater than the discharge volume per unit time if the oil level scale is lower than a preset threshold.

[0014] Furthermore, the control module includes a control unit for continuously energizing the first capacity regulating solenoid valve of the compressor and pulse-energizing the second capacity regulating solenoid valve of the compressor, wherein the load of the first capacity regulating solenoid valve is less than that of the second capacity regulating solenoid valve.

[0015] Furthermore, if the oil level scale is lower than a preset threshold, the device further includes: an acquisition module for acquiring the superheat and temperature change rate of the compressor; and an adjustment module for adjusting the opening of the electronic expansion valve according to the superheat and the temperature change rate, wherein one end of the electronic expansion valve is connected to the exhaust side of the compressor via an air-cooled heat exchanger, and the other end of the electronic expansion valve is connected to the suction side of the compressor via a cold water-side heat exchanger.

[0016] Furthermore, the acquisition module includes: a data acquisition unit, used to acquire the intake temperature and first pressure of the compressor on the intake side, and the exhaust temperature and second pressure of the compressor on the exhaust side; a calculation unit, used to calculate a first temperature difference between the intake temperature and the saturation temperature corresponding to the first pressure, a second temperature difference between the exhaust temperature and the saturation temperature corresponding to the second pressure, a third temperature difference between the intake temperature and a historical intake temperature, and a fourth temperature difference between the exhaust temperature and a historical exhaust temperature; and a determination unit, used to determine the first temperature difference as intake superheat, the second temperature difference as exhaust superheat, the third temperature difference as intake temperature change rate, and the fourth temperature difference as exhaust temperature change rate, wherein the superheat includes the intake superheat or the exhaust superheat, and the temperature change rate includes the intake temperature change rate or the exhaust temperature change rate.

[0017] Furthermore, the adjustment module includes: a judgment unit, used to judge whether the superheat is greater than or equal to the superheat threshold, whether the temperature change rate is greater than or equal to the change rate threshold, and whether the temperature change rate is greater than or equal to 0; and an increase unit, used to increase the opening of the electronic expansion valve by a preset step size if the superheat is greater than or equal to the superheat threshold, the temperature change rate is greater than or equal to the change rate threshold, and the temperature change rate is greater than or equal to 0.

[0018] Furthermore, the adjustment module also includes a reduction unit, used to reduce the opening of the electronic expansion valve by a preset step size if the superheat is less than the superheat threshold and the temperature change rate is less than the change rate threshold.

[0019] Furthermore, the device includes: a detection module for detecting an oil level alarm signal of the compressor before the monitoring module monitors the oil level scale of the compressor's refrigeration oil; and an activation module for activating the oil return mode in response to the oil level alarm signal.

[0020] According to another aspect of the embodiments of this application, an air-cooled water chiller unit is also provided, including the apparatus as described in the above embodiments.

[0021] According to another aspect of the embodiments of this application, a computer-readable storage medium is also provided, the storage medium including a stored program that executes the above-described steps when the program is run.

[0022] According to another aspect of the embodiments of this application, an electronic device is also provided, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; wherein: the memory is used to store computer programs; and the processor is used to execute the steps in the above method by running the programs stored in the memory.

[0023] This application also provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the steps in the above-described method.

[0024] By applying the technical solution of this invention, the oil level of the compressor's refrigeration oil is monitored. If the oil level is lower than a preset threshold, the compressor's intake volume is controlled to be greater than its discharge volume per unit time. This achieves a compressor control scheme. By increasing the compressor's intake volume and reducing its discharge volume, rapid oil return is achieved, solving the technical problem of low oil return efficiency in existing compressors. Rapid oil return is achieved without adding extra equipment, improving the compressor's oil return efficiency while ensuring compressor reliability and without increasing hardware costs. Attached Figure Description

[0025] Figure 1 This is a flowchart of a return oil control method according to an embodiment of the present invention;

[0026] Figure 2 This is a structural diagram of the compressor oil return system in an embodiment of the present invention;

[0027] Figure 3 This is a flowchart of the compressor oil return control according to an embodiment of the present invention;

[0028] Figure 4 This is a structural block diagram of a return oil control device according to an embodiment of the present invention. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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).”

[0033] 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.

[0034] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] Example 1

[0036] Figure 1 This is a flowchart of the oil return control method according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes the following steps:

[0037] Step S102: Monitor the oil level of the compressor's refrigeration oil.

[0038] The compressor in this embodiment can be any model that requires oil return, such as a screw compressor. The compressor has a built-in oil separator.

[0039] Refrigeration oil is an important medium for keeping the compressor working properly. Under the premise that the compressor's lubrication, sealing, cooling and energy regulation functions are normal, the oil level of the refrigeration oil should not be lower than the preset threshold.

[0040] Step S104: If the oil level is lower than the preset threshold, control the compressor to have a greater intake volume than exhaust volume per unit time.

[0041] Through the above steps, the oil level of the compressor's refrigeration oil is monitored. If the oil level is lower than the preset threshold, the compressor's intake volume is controlled to be greater than its discharge volume per unit time. This achieves a compressor control scheme. By increasing the compressor's intake volume and reducing its discharge volume, rapid oil return is achieved, solving the technical problem of low compressor oil return efficiency in the prior art. Rapid oil return of the compressor is achieved without adding extra equipment. Under the premise of ensuring compressor reliability and without increasing hardware costs, the compressor's oil return efficiency is improved.

[0042] In an embodiment, controlling the compressor to have a greater intake volume than exhaust volume per unit time includes: continuously energizing the first capacity regulating solenoid valve of the compressor and pulse-energizing the second capacity regulating solenoid valve of the compressor, wherein the load of the first capacity regulating solenoid valve is less than that of the second capacity regulating solenoid valve.

[0043] Optionally, the first capacity regulating solenoid valve is a 50% capacity regulating solenoid valve, and the second capacity regulating solenoid valve is a 100% capacity regulating solenoid valve. Of course, other capacity regulating valves with different load combinations can also be selected.

[0044] In one example, the pulse cycle of the second capacity regulating solenoid valve is 1 second of energization and 4 seconds of de-energization.

[0045] As the discharge pressure gradually rises, before reaching the upper limit of the system's set pressure, it first reaches the set pressure of the pressure regulator, causing the intake valve to gradually close. At this point, the system begins capacity regulation. If the pressure continues to rise, the intake valve gradually closes until it is completely closed. Conversely, if the system pressure gradually decreases, the intake valve gradually opens, and the intake volume and pressure gradually increase until they fall below the set value of the pressure regulator, at which point the capacity regulation stops. Capacity regulation is achieved by applying different pulse patterns to the two solenoid valves, increasing the compressor's intake volume, reducing the compressor's discharge volume, and increasing the residence time of the oil-gas mixture in the built-in oil separator, thereby effectively preventing refrigerant oil from being discharged into the refrigerant system.

[0046] In one embodiment of this invention, if the oil level reading is lower than a preset threshold, the method further includes:

[0047] S11, obtain the superheat and temperature change rate of the compressor;

[0048] In one example, obtaining the compressor's superheat and temperature change rate includes: acquiring the compressor's suction temperature and first pressure on the suction side, and acquiring the compressor's discharge temperature and second pressure on the discharge side; calculating a first temperature difference between the suction temperature and the saturation temperature corresponding to the first pressure, calculating a second temperature difference between the discharge temperature and the saturation temperature corresponding to the second pressure, calculating a third temperature difference between the suction temperature and a historical suction temperature, and calculating a fourth temperature difference between the discharge temperature and a historical discharge temperature; determining the first temperature difference as suction superheat, the second temperature difference as discharge superheat, the third temperature difference as suction temperature change rate, and the fourth temperature difference as discharge temperature change rate, wherein superheat includes suction superheat or discharge superheat, and temperature change rate includes suction temperature change rate or discharge temperature change rate.

[0049] The rate of temperature change in this embodiment is used to characterize the rate of change of the current temperature relative to historical temperatures.

[0050] Figure 2 This is a structural diagram of the compressor oil return system in an embodiment of the present invention, including: compressor 1, air-cooled heat exchanger 2, electronic expansion valve 3, and water-side heat exchanger 4. The oil return circuit is as follows: compressor 1 → air-cooled heat exchanger 2 → electronic expansion valve 3 → water-side heat exchanger 4 → compressor 1.

[0051] In this embodiment, the intake temperature Td is the temperature sensed by the intake temperature sensor, the low pressure (first pressure) Pd is the pressure sensed by the pressure sensor and is collected on the intake side of the compressor, the exhaust temperature Th is the temperature sensed by the exhaust temperature sensor, and the exhaust pressure (second pressure) Ph is the pressure sensed by the exhaust pressure sensor and is collected on the exhaust side of the compressor.

[0052] Intake superheat ΔTd = intake temperature Td - saturation temperature corresponding to low pressure Pd;

[0053] Exhaust superheat ΔTh = Exhaust temperature Th - Saturation temperature corresponding to exhaust pressure Ph.

[0054] Inhalation temperature change rate ΔTdb = current inhalation temperature value Td (t) -Inhalation temperature Td one minute prior to the current time point (t-60) ;

[0055] Exhaust temperature change rate ΔThb = Current exhaust temperature value Th (t) -Exhaust temperature value Th one minute prior to the current time point (t-60) ;

[0056] Table 1 is used as an example to explain the range and interpretation of each parameter:

[0057] Table 1

[0058]

[0059]

[0060] In the above example, the sampling interval between the inhalation temperature and the historical inhalation temperature, and between the exhaust temperature and the historical exhaust temperature, is one minute (60 seconds). This interval can also be adjusted as needed, such as to 10 seconds.

[0061] S12 adjusts the opening of the electronic expansion valve according to the superheat and the rate of temperature change. One end of the electronic expansion valve is connected to the exhaust side of the compressor through an air-cooled heat exchanger, and the other end of the electronic expansion valve is connected to the suction side of the compressor through a chilled water heat exchanger.

[0062] Optionally, before adjusting the opening of the electronic expansion valve, set the opening of the electronic expansion valve to the initial opening, such as 50%, to minimize the adjustment time.

[0063] In one aspect of this embodiment, adjusting the opening of the electronic expansion valve based on superheat and temperature change rate includes: determining whether the superheat is greater than or equal to a superheat threshold, determining whether the temperature change rate is greater than or equal to a change rate threshold, and determining whether the temperature change rate is greater than or equal to 0; if the superheat is greater than or equal to the superheat threshold, the temperature change rate is greater than or equal to the change rate threshold, and the temperature change rate is greater than or equal to 0, the opening of the electronic expansion valve is increased by a preset step size.

[0064] In this embodiment, while controlling the compressor's intake volume to be greater than its discharge volume per unit time, the opening of the electronic expansion valve is adjusted. Within a safe range, the opening is allowed to be increased, so that the refrigerant oil in the system returns to the compressor more quickly and liquid is prevented from being carried into the compressor's intake.

[0065] In this embodiment, the superheat includes intake superheat and exhaust superheat, and the temperature change rate includes intake temperature change rate and exhaust temperature change rate. When the intake parameters (intake superheat and intake temperature change rate) are greater than or equal to the intake threshold or the exhaust parameters (exhaust superheat and exhaust temperature change rate) are greater than or equal to the exhaust threshold, that is, when the superheat and temperature change rate meet condition 1 or condition 2, the opening of the electronic expansion valve is increased.

[0066] Condition 1, which simultaneously satisfies the following conditions:

[0067] Intake superheat ΔTd ≥ Intake superheat threshold ΔTdm;

[0068] Inhalation temperature change rate ΔTdb ≥ Inhalation temperature change rate threshold ΔTdbm;

[0069] Inhalation temperature change rate ΔTdb≥0

[0070] Condition 2, which must simultaneously meet the following conditions

[0071] Exhaust superheat ΔTh ≥ Exhaust superheat threshold ΔThm;

[0072] The exhaust temperature change rate ΔThb ≥ the exhaust temperature change rate threshold ΔThbm;

[0073] The rate of change of exhaust temperature ΔThb ≥ 0.

[0074] In another aspect of this embodiment, it further includes: if the superheat is less than the superheat threshold and the rate of temperature change is less than the rate of change threshold, reducing the opening of the electronic expansion valve by a preset step size.

[0075] When the intake parameters (gas superheat and intake temperature change rate) are less than the intake threshold or the exhaust parameters (exhaust superheat and exhaust temperature change rate) are less than the exhaust threshold, i.e. when the superheat and temperature change rate meet condition 3 or condition 4, the opening of the electronic expansion valve is reduced.

[0076] Condition 3, which simultaneously satisfies the following conditions:

[0077] Intake superheat ΔTd < Intake superheat threshold ΔTdm

[0078] Inhalation temperature change rate ΔTdb < Inhalation temperature change rate threshold ΔTdbm;

[0079] Condition 4, which simultaneously satisfies the following conditions:

[0080] Exhaust superheat ΔTh < Exhaust superheat threshold ΔThm;

[0081] The exhaust temperature change rate ΔThb < the exhaust temperature change rate threshold ΔThbm.

[0082] Optionally, before monitoring the compressor's refrigeration oil level, the following steps may be taken: detecting the compressor's oil level alarm signal; and responding to the oil level alarm signal by activating the oil return mode.

[0083] In this embodiment, the oil level alarm signal can be transmitted to the main control unit of the oil return control, and can also be output to the control interface of the compressor system to alert the user through audible and visual signals so that the user can pay attention to the fault and repair it as soon as possible.

[0084] Figure 3 This is a flowchart of the compressor oil return control according to an embodiment of the present invention. The flowchart includes:

[0085] S31, compressor oil level alarm signal detected and activated;

[0086] S32, automatic oil return mode activated;

[0087] S33, the compressor 50% capacity adjustment solenoid valve is continuously energized, and the compressor 100% capacity adjustment solenoid valve is energized with pulses;

[0088] S34, the electronic expansion valve opens to the "initial opening of the electronic expansion valve return oil degree", starting the control of the electronic expansion valve:

[0089] S35, if either condition one or condition two is met for 30 consecutive seconds, the electronic expansion valve opens ΔDc, such as ΔDc = 1%;

[0090] Case 1: The following conditions must be met simultaneously:

[0091] Intake superheat ΔTd ≥ Intake superheat threshold ΔTdm

[0092] Inhalation temperature change rate ΔTdb ≥ Inhalation temperature change rate threshold ΔTdbm;

[0093] The rate of change of intake temperature ΔTdb ≥ 0.

[0094] Scenario 2: The following conditions must be met simultaneously:

[0095] Exhaust superheat ΔTh ≥ Exhaust superheat threshold ΔThm;

[0096] The exhaust temperature change rate ΔThb ≥ the exhaust temperature change rate threshold ΔThbm;

[0097] The rate of change of exhaust temperature ΔThb ≥ 0.

[0098] S36. If condition three or four is met for 15 consecutive seconds, the electronic expansion valve closes △Dc.

[0099] Scenario 3: The following conditions must be met simultaneously:

[0100] Intake superheat ΔTd < Intake superheat threshold ΔTdm;

[0101] The rate of change of inhalation temperature ΔTdb < the threshold value of the rate of change of inhalation temperature ΔTdbm.

[0102] Scenario 4: The following conditions are met simultaneously:

[0103] Exhaust superheat ΔTh < Exhaust superheat threshold ΔThm;

[0104] The exhaust temperature change rate ΔThb < the exhaust temperature change rate threshold ΔThbm.

[0105] (3) In other cases, the electronic expansion valve maintains its current opening.

[0106] The compressor oil level alarm signal was detected and the automatic oil return mode was turned off.

[0107] After the return oil mode is closed, the capacity regulating solenoid valve performs loading, unloading, and holding control as needed by the system. For example, unloading: the 50% capacity regulating solenoid valve is energized by pulse, and the 100% capacity regulating solenoid valve is de-energized; loading: the 50% capacity regulating solenoid valve is de-energized, and the 100% capacity regulating solenoid valve is energized by pulse; holding: neither the 50% nor the 100% capacity regulating solenoid valve is energized.

[0108] The oil return control scheme of this embodiment achieves rapid oil return of the compressor by increasing the compressor's suction volume and reducing the discharge volume, and by reducing the risk of liquid carryover in the suction volume through suction and discharge superheat. This achieves rapid oil return of the compressor without adding any additional equipment.

[0109] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, 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 is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0110] Example 2

[0111] like Figure 4 As shown, according to a specific embodiment of the present invention, in a second aspect, the present invention provides a return oil control device, corresponding to... Figure 1 The described oil return control method is illustrated in this embodiment, which provides an oil return control device. Figure 4 This is a structural block diagram of a return oil control device according to an embodiment of the present invention. The device includes:

[0112] Monitoring module 40 is used to monitor the oil level scale of the compressor refrigeration oil;

[0113] The control module 42 is used to control the compressor to have a greater intake volume than exhaust volume per unit time if the oil level scale is lower than a preset threshold.

[0114] Optionally, the control module includes: a control unit, used to control the first capacity regulating solenoid valve of the compressor to be continuously energized, and to control the second capacity regulating solenoid valve of the compressor to be energized in a pulsed manner, wherein the load of the first capacity regulating solenoid valve is less than that of the second capacity regulating solenoid valve.

[0115] Optionally, if the oil level is lower than a preset threshold, the device further includes: an acquisition module for acquiring the superheat and temperature change rate of the compressor; and an adjustment module for adjusting the opening of the electronic expansion valve according to the superheat and the temperature change rate, wherein one end of the electronic expansion valve is connected to the exhaust side of the compressor via an air-cooled heat exchanger, and the other end of the electronic expansion valve is connected to the suction side of the compressor via a cold water-side heat exchanger.

[0116] Optionally, the acquisition module includes: a collection unit, used to collect the intake temperature and first pressure of the compressor on the intake side, and the exhaust temperature and second pressure of the compressor on the exhaust side; a calculation unit, used to calculate a first temperature difference between the intake temperature and the saturation temperature corresponding to the first pressure, a second temperature difference between the exhaust temperature and the saturation temperature corresponding to the second pressure, a third temperature difference between the intake temperature and a historical intake temperature, and a fourth temperature difference between the exhaust temperature and a historical exhaust temperature; and a determination unit, used to determine the first temperature difference as intake superheat, the second temperature difference as exhaust superheat, the third temperature difference as intake temperature change rate, and the fourth temperature difference as exhaust temperature change rate, wherein the superheat includes the intake superheat or the exhaust superheat, and the temperature change rate includes the intake temperature change rate or the exhaust temperature change rate.

[0117] Optionally, the adjustment module includes: a judgment unit, used to judge whether the superheat is greater than or equal to a superheat threshold, whether the temperature change rate is greater than or equal to a change rate threshold, and whether the temperature change rate is greater than or equal to 0; and an increase unit, used to increase the opening of the electronic expansion valve by a preset step size if the superheat is greater than or equal to a superheat threshold, the temperature change rate is greater than or equal to a change rate threshold, and the temperature change rate is greater than or equal to 0.

[0118] Optionally, the adjustment module further includes a reduction unit, used to reduce the opening of the electronic expansion valve by a preset step size if the superheat is less than the superheat threshold and the temperature change rate is less than the change rate threshold.

[0119] Optionally, the device includes: a detection module for detecting an oil level alarm signal of the compressor before the monitoring module monitors the oil level scale of the compressor refrigeration oil; and an activation module for activating the oil return mode in response to the oil level alarm signal.

[0120] Thirdly, the present invention provides an air-cooled water chiller unit, including as follows: Figure 4 The components shown include an oil return control device, a compressor, an air-cooled heat exchanger, an electronic expansion valve, and a chilled water side heat exchanger.

[0121] It should be noted that the above modules can be implemented by software or hardware. For the latter, they can be implemented in the following ways, but are not limited to: all the above modules are located in the same processor; or, the above modules are located in different processors in any combination.

[0122] Example 3

[0123] This embodiment provides an electronic device for executing a return oil control method. The electronic device includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein...

[0124] The memory stores instructions that can be executed by the processor, and the instructions are executed by the at least one processor to enable the at least one processor to: monitor the oil level of the compressor's refrigeration oil; and if the oil level is lower than a preset threshold, control the compressor to have a suction volume greater than its discharge volume per unit time.

[0125] Furthermore, controlling the compressor to have a greater intake volume than exhaust volume per unit time includes: continuously energizing the first capacity regulating solenoid valve of the compressor and pulse-energizing the second capacity regulating solenoid valve of the compressor, wherein the load of the first capacity regulating solenoid valve is less than that of the second capacity regulating solenoid valve.

[0126] Furthermore, if the oil level scale is lower than a preset threshold, the method further includes: obtaining the superheat and temperature change rate of the compressor; adjusting the opening of the electronic expansion valve according to the superheat and the temperature change rate, wherein one end of the electronic expansion valve is connected to the exhaust side of the compressor via an air-cooled heat exchanger, and the other end of the electronic expansion valve is connected to the suction side of the compressor via a cold water-side heat exchanger.

[0127] Further, obtaining the superheat and temperature change rate of the compressor includes: collecting the suction temperature and first pressure of the compressor on the suction side, and collecting the discharge temperature and second pressure of the compressor on the discharge side; calculating a first temperature difference between the suction temperature and the saturation temperature corresponding to the first pressure, calculating a second temperature difference between the discharge temperature and the saturation temperature corresponding to the second pressure, calculating a third temperature difference between the suction temperature and a historical suction temperature, and calculating a fourth temperature difference between the discharge temperature and a historical discharge temperature; determining the first temperature difference as the suction superheat, the second temperature difference as the discharge superheat, the third temperature difference as the suction temperature change rate, and the fourth temperature difference as the discharge temperature change rate, wherein the superheat includes the suction superheat or the discharge superheat, and the temperature change rate includes the suction temperature change rate or the discharge temperature change rate.

[0128] Further, adjusting the opening of the electronic expansion valve according to the superheat and the rate of temperature change includes: determining whether the superheat is greater than or equal to a superheat threshold, determining whether the rate of temperature change is greater than or equal to a rate of change threshold, and determining whether the rate of temperature change is greater than or equal to 0; if the superheat is greater than or equal to the superheat threshold, the rate of temperature change is greater than or equal to the rate of change threshold, and the rate of temperature change is greater than or equal to 0, increasing the opening of the electronic expansion valve by a preset step size.

[0129] Furthermore, the method also includes: if the superheat is less than the superheat threshold and the temperature change rate is less than the change rate threshold, reducing the opening of the electronic expansion valve by a preset step size.

[0130] Furthermore, before monitoring the oil level scale of the compressor's refrigeration oil, the method includes: detecting the oil level alarm signal of the compressor; and responding to the oil level alarm signal by activating the oil return mode.

[0131] Example 4

[0132] 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.

[0133] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; 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.

[0134] 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., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0135] 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, characterized in that, include: Monitor the compressor's refrigeration oil level scale; If the oil level is lower than a preset threshold, the compressor is controlled to have a greater intake volume than exhaust volume per unit time. If the oil level reading is lower than a preset threshold, the method further includes: Obtain the superheat and temperature change rate of the compressor; The opening of the electronic expansion valve is adjusted according to the superheat and the rate of temperature change. One end of the electronic expansion valve is connected to the exhaust side of the compressor via an air-cooled heat exchanger, and the other end of the electronic expansion valve is connected to the suction side of the compressor via a cold water heat exchanger. Adjusting the opening of the electronic expansion valve based on the superheat and the rate of temperature change includes: Determine whether the superheat is greater than or equal to a superheat threshold, determine whether the temperature change rate is greater than or equal to a change rate threshold, and determine whether the temperature change rate is greater than or equal to 0. If the superheat is greater than or equal to the superheat threshold, the temperature change rate is greater than or equal to the change rate threshold, and the temperature change rate is greater than or equal to 0, the opening of the electronic expansion valve is increased by a preset step size.

2. The method according to claim 1, characterized in that, Controlling the compressor to ensure that the intake volume is greater than the discharge volume per unit time includes: The first capacity regulating solenoid valve of the compressor is continuously energized, and the second capacity regulating solenoid valve of the compressor is pulsedly energized, wherein the load of the first capacity regulating solenoid valve is less than that of the second capacity regulating solenoid valve.

3. The method according to claim 1, characterized in that, Obtaining the superheat and temperature change rate of the compressor includes: The compressor's intake temperature and first pressure on the intake side are collected, as well as its exhaust temperature and second pressure on the exhaust side. Calculate the first temperature difference between the intake temperature and the saturation temperature corresponding to the first pressure, calculate the second temperature difference between the exhaust temperature and the saturation temperature corresponding to the second pressure, calculate the third temperature difference between the intake temperature and the historical intake temperature, and calculate the fourth temperature difference between the exhaust temperature and the historical exhaust temperature. The first temperature difference is defined as the intake superheat, the second temperature difference is defined as the exhaust superheat, the third temperature difference is defined as the intake temperature change rate, and the fourth temperature difference is defined as the exhaust temperature change rate. The superheat includes the intake superheat or the exhaust superheat, and the temperature change rate includes the intake temperature change rate or the exhaust temperature change rate.

4. The method according to claim 1, characterized in that, The method further includes: If the superheat is less than the superheat threshold and the temperature change rate is less than the change rate threshold, the opening of the electronic expansion valve is reduced by a preset step size.

5. The method according to claim 1, characterized in that, Before monitoring the compressor refrigeration oil level scale, the method includes: Detect the oil level alarm signal of the compressor; In response to the oil level alarm signal, the oil return mode is activated.

6. A return oil control device, characterized in that, include: The monitoring module is used to monitor the oil level scale of the compressor's refrigeration oil; The control module is used to control the compressor to have a greater intake volume than exhaust volume per unit time if the oil level scale is lower than a preset threshold. If the oil level reading is lower than a preset threshold, the device further includes: The acquisition module is used to acquire the superheat and temperature change rate of the compressor; An adjustment module is used to adjust the opening of the electronic expansion valve according to the superheat and the rate of temperature change. One end of the electronic expansion valve is connected to the exhaust side of the compressor via an air-cooled heat exchanger, and the other end of the electronic expansion valve is connected to the suction side of the compressor via a cold water heat exchanger. The adjustment module includes: The judgment unit is used to determine whether the superheat is greater than or equal to the superheat threshold value, whether the temperature change rate is greater than or equal to the change rate threshold value, and whether the temperature change rate is greater than or equal to 0. An additional unit is added to increase the opening of the electronic expansion valve by a preset step size if the superheat is greater than or equal to the superheat threshold, the temperature change rate is greater than or equal to the change rate threshold, and the temperature change rate is greater than or equal to 0.

7. An air-cooled water chiller unit, characterized in that, The air-cooled water chiller unit includes the oil return control device as described in claim 6.

8. 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 method as described in any one of claims 1 to 5.

9. 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 method as described in any one of claims 1 to 5.

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