Refrigeration apparatus, electronic expansion valve and automatic adjustment control method thereof

Abstract

The application discloses a refrigeration equipment, an electronic expansion valve and an automatic adjusting control method thereof. The automatic adjusting control method of the electronic expansion valve comprises the following steps: judging whether the refrigeration system is in a low pressure too low state; when the refrigeration system is in the low pressure too low state, controlling the electronic expansion valve to automatically adjust according to different action times in a control time period according to the low pressure too low degree in the evaporator; and when the low pressure of the refrigeration system is in a normal state, controlling the electronic expansion valve to adjust to place once. The application effectively solves the problems of the reaction lag of the whole system caused by the untimely control and adjustment of the electronic expansion valve when the low pressure in the unit is too low, and the insufficient adjustment precision once.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, and in particular to a refrigeration device, an electronic expansion valve, and an automatic adjustment and control method thereof. Background Technology

[0002] An electronic expansion valve is a throttling element that controls the refrigerant flow rate of a refrigeration system according to a preset program. It is not only an important control component of a refrigeration system but has also become an indispensable part of achieving intelligent control of refrigeration systems. In a refrigeration system, the electronic expansion valve mainly plays a crucial role in regulating flow rate, controlling superheat, throttling and reducing pressure, and controlling the evaporator level. The electronic expansion valve achieves its regulation purpose by controlling the operating voltage or current of the electronic expansion valve through an electrical signal generated by the regulated parameter. In practical applications, improper control of the electronic expansion valve during low-pressure regulation in the refrigeration system often leads to continuous standby or even damage to the unit. Specifically, this manifests as the electronic expansion valve failing to exit the low-pressure regulation state normally after entering it, the electronic expansion valve continuously operating causing the control system to report low-pressure protection, and the unit failing to restart normally after an emergency stop.

[0003] Furthermore, existing units adjust the electronic expansion valve in a single, rapid adjustment, but the system's actual response requires a certain amount of time, thus introducing a lag problem. Additionally, single-adjustment also suffers from the problem of the electronic expansion valve losing synchronization, resulting in insufficient adjustment precision. Therefore, proper control of the electronic expansion valve is a crucial factor in achieving intelligent system control and ensuring the safe operation of the unit. Summary of the Invention

[0004] This invention proposes a refrigeration equipment, an electronic expansion valve, and its automatic adjustment and control method to solve the technical problems in the prior art, such as adjustment loss, insufficient adjustment accuracy, continuous standby or even damage of the unit caused by the electronic expansion valve's single adjustment when the system pressure is too low.

[0005] This invention proposes an automatic adjustment and control method for an electronic expansion valve, comprising the following steps: Determine the low-pressure state of the refrigeration system; When the refrigeration system is in a low-pressure state, the electronic expansion valve is automatically adjusted according to the degree of low pressure in the system within an adjustment time cycle, with different number of actuations. When the low pressure of the refrigeration system is in a normal state, the electronic expansion valve is controlled to adjust according to the normal procedure and adjust to the correct position in one go.

[0006] Preferably, the condition for determining the low-pressure state is: the rate of decrease in system evaporation temperature is less than or equal to a set value, Q≤-m℃ / min.

[0007] In one embodiment, the condition for determining the low-pressure state is: the absolute value of the rate of decrease in system evaporation pressure is less than or equal to a set value, X≤hPa / min.

[0008] Furthermore, when the refrigeration system is in a low-pressure state and needs to operate n times within one adjustment time cycle, first increase the opening of the electronic expansion valve by k%, then operate once every time interval t. After completing the n operations within one adjustment time cycle T, determine whether the rate of decrease of the system evaporating temperature is greater than the set value -m℃ / min. If so, reset the number of operations n of the electronic expansion valve and the adjustment time cycle T to zero and exit the adjustment. If not, repeat the above low-pressure adjustment according to the low-pressure condition.

[0009] Preferably, the interval time t is evenly distributed according to the number of actions.

[0010] Preferably, the number of different actions n is greater than or equal to 1 and less than or equal to 3.

[0011] Preferably, the adjustment time period T is selected based on the ambient temperature, the rate of change of evaporation temperature, and the compressor operating frequency, with different adjustment time periods corresponding to different operating conditions.

[0012] Furthermore, within each adjustment time period T, a first danger threshold and a second danger threshold are given for the rate of decrease of evaporation temperature. When the rate of decrease of evaporation temperature is less than or equal to the first danger threshold, the electronic expansion valve operates a times. When the rate of decrease of evaporation temperature is greater than the first danger threshold and less than or equal to the second danger threshold, the electronic expansion valve operates b times. When the rate of decrease of evaporation temperature is greater than the second danger threshold, the electronic expansion valve operates c times.

[0013] Preferably, the first danger threshold and the second danger threshold are determined experimentally based on ambient temperature, evaporation temperature change rate, and compressor operating frequency.

[0014] Preferably, parameter a is 1 time, b is 2 times, and c is 3 times.

[0015] The present invention also proposes an electronic expansion valve, which operates using the above-described automatic adjustment and control method.

[0016] The present invention also proposes a refrigeration device, wherein the electronic expansion valve of the refrigeration device operates using the above-described automatic adjustment and control method.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The technical solution proposed in this application effectively solves the problem that the unit will continuously stand by due to improper low pressure regulation control, or the electronic expansion valve will not be able to exit the low pressure regulation normally after entering the low pressure regulation, resulting in the refrigeration equipment control system reporting low pressure protection and the unit failing to start normally after emergency stop; 2. The technical solution proposed in this application solves the problem of large adjustment deviation that often occurs in single adjustment. Multiple adjustments can improve the electronic expansion valve's step loss and achieve the purpose of fine adjustment, while improving the reliability and stability of the unit. 3. The technical solution proposed in this application can prevent excessive liquid in the evaporator from being carried into the compressor due to excessively low pressure, thereby improving the life of the compressor; 4. The technical solution proposed in this application effectively solves the problem of delayed response of the entire system due to untimely control and adjustment of the electronic expansion valve when the unit system is in a low-pressure state, and effectively gives full play to the throttling and pressure reduction function of the electronic expansion valve; 5. The technical solution proposed in this application effectively controls the temperature and pressure of the refrigerant entering the evaporator by controlling the excessively low pressure. This improves the heat exchange capacity of the evaporator, meets the needs of air conditioning, enhances the cooling effect, and improves system stability and user experience. Attached Figure Description

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, wherein: Figure 1 This is a schematic diagram comparing single and multiple adjustments of an electronic expansion valve. Figure 2 This is a schematic diagram of the control method of the present invention; Figure 3 A flowchart showing the multiple actions of the electronic expansion valve when the pressure is too low; Figure 4 This is a flowchart of an embodiment of the control method of the present invention; Figure 5 This is a flowchart of another embodiment of the control method of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the following specific embodiments are only used to explain the invention and do not constitute a limitation thereof.

[0020] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Furthermore, it should be noted that the terms "first" and "second" used in this specification to describe components or parameters are merely for the purpose of distinguishing the corresponding components or parameters. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0022] Typically, electronic expansion valves determine whether adjustment is needed based on the deviation between the intake superheat and the target superheat. When adjustment is required, it's done in a single action, theoretically allowing for rapid, one-step adjustment. However, this method often overlooks the issues of poor accuracy in single adjustments and the lag caused by the electronic expansion valve's rapid adjustment. This is because an overly rapid adjustment means the system hasn't yet completed the control of other loads, requiring a buffer period. These loads include the control of fan frequency, compressor frequency, and water pumps.

[0023] Furthermore, in practical applications, when the system is in a low-pressure state, the electronic expansion valve often fails to exit the low-pressure regulation properly after entering the low-pressure regulation due to improper control during the first adjustment. The electronic expansion valve continues to operate, the control system reports low-pressure protection, the unit cannot start normally after emergency shutdown, and there may even be component damage.

[0024] To address the above problems, the present invention proposes a judgment condition that reflects the degree of low system pressure. When the system experiences low pressure, the electronic expansion valve is controlled to automatically adjust according to the degree of low pressure, triggering different numbers of actions with each adjustment. Experiments have shown that this adjustment method not only solves the problem of large adjustment deviations often occurring with a single adjustment, but also improves the problem of the electronic expansion valve losing synchronization due to multiple actions in a single adjustment, achieving fine adjustment of the electronic expansion valve.

[0025] Figure 1 This is a comparative diagram of single and multiple adjustments of an electronic expansion valve. It is clear from the diagram that in a single adjustment, neither a single action nor two actions could reach the target number of steps, while three actions with evenly distributed intervals achieved the target number of steps. Figure 1The illustrated embodiment demonstrates that performing a single adjustment in multiple actions can effectively improve the problem of electronic expansion valve losing synchronization, thereby improving the adjustment accuracy of the electronic expansion valve.

[0026] Figure 2 This is a schematic diagram of the automatic adjustment and control method for the electronic expansion valve proposed in this invention. The control method proposed in this invention includes the following steps: Determine the low-pressure state of the refrigeration system; When the refrigeration system is in a low-pressure state, the electronic expansion valve is controlled to complete the adjustment by different numbers of actions within one adjustment cycle according to the low-pressure state. When the low pressure of the refrigeration system is in a normal state, the electronic expansion valve is adjusted according to the normal control method, and the adjustment is completed in one step.

[0027] Preferably, the condition for determining the low-pressure state is: the rate of decrease of the system evaporation temperature Q is less than or equal to the set value -m℃ / min, and Q≤-m℃ / min.

[0028] The rate of temperature decrease of evaporation, Q, is calculated based on the detected evaporation temperature. Specifically, it is calculated as the difference between the evaporation temperature at the current moment and the evaporation temperature at the previous moment per unit time, and the result is a negative value.

[0029] The function of the electronic expansion valve is to convert high-pressure refrigerant liquid at room temperature into low-temperature, low-pressure liquid. A small amount of flash gas is generated during the conversion process. After the pressure is reduced, the refrigerant liquid exchanges heat with the air in the evaporator, thereby accurately absorbing indoor heat to meet the needs of air conditioning. Therefore, properly controlling the problem of excessively low pressure is crucial.

[0030] The automatic adjustment and control method for electronic expansion valves proposed in this invention effectively solves the problem of response lag caused by single adjustment. It also solves the problem that after the electronic expansion valve enters the low-pressure adjustment, it cannot exit the adjustment normally and continues to operate, causing the unit to be in continuous standby or even damaged.

[0031] The most significant contribution of this invention is the development of a judgment condition that accurately reflects the low pressure within the system. This judgment condition is that the rate of temperature decrease in evaporation is lower than a set value. The rate of temperature decrease can be calculated from the detected evaporation temperature; the difference between the current evaporation temperature and the previous evaporation temperature, divided by time, gives the rate of temperature decrease. The judgment condition for low system pressure is: the rate of temperature decrease in evaporation, Q, is less than or equal to the set value -m℃ / min, and Q ≤ -m℃ / min. When the system low pressure meets this condition, the electronic expansion valve enters low pressure regulation, meaning that a single regulation can be completed with different number of actions.

[0032] In existing technologies, electronic expansion valves adjust in a single step according to a set target number of steps. However, this approach is unreasonable. If high adjustment precision is required, excessive load pressure during the excitation process can easily lead to step loss. This invention proposes selecting different numbers of actions per adjustment based on the degree of low pressure. When multiple adjustments are performed at intervals t, the stepper motor within the valve body avoids excessive load pressure, ensuring each step is a genuine adjustment. Therefore, the automatic adjustment control of the electronic expansion valve proposed in this invention changes the number of adjustments per time from once to selecting different numbers of actions based on the degree of low pressure, thereby improving the accuracy of electronic expansion valve control. On the other hand, too many adjustments per time would prolong the entire adjustment cycle, which does not meet the requirement of rapid adjustment. Therefore, the number of adjustments per time should be set within a reasonable range.

[0033] Extensive experiments have shown that setting the number of adjustments (n) of the electronic expansion valve to be greater than or equal to 1 and less than or equal to 3, with 1 ≤ n ≤ 3, can effectively solve the problem of step loss in electronic expansion valve adjustment and improve the accuracy of electronic expansion valve control.

[0034] Numerous experiments have shown that factors such as ambient temperature, evaporation temperature change rate, and compressor operating frequency can reflect the degree of low pressure. When the low pressure is severe, the adjustment cycle T should be shorter; otherwise, it may trigger the compressor's low-pressure protection, leading to shutdown. Conversely, the adjustment cycle T should be longer. Therefore, the adjustment cycle T of the electronic expansion valve can be experimentally selected based on factors such as ambient temperature, evaporation temperature change rate, and compressor operating frequency. Different operating conditions correspond to different adjustment cycles. The number of actions n within each adjustment cycle T is set based on the degree of low pressure and experimental data. In one embodiment, two danger thresholds reflecting the rate of evaporation temperature decrease in the refrigeration system are given to reflect the degree of low pressure: a first danger threshold of -m1℃ / min and a second danger threshold of -m2℃ / min. These two danger thresholds are determined experimentally using parameters such as ambient temperature, evaporation temperature change rate, and compressor operating frequency, and can accurately determine the degree of low pressure in the unit. When the rate of temperature drop in evaporation, Q, is less than or equal to the first danger threshold (Q ≤ -m1℃ / min), the evaporator pressure is severely low. The electronic expansion valve will only activate once for a rapid response, preventing the unit from triggering low-pressure protection or even shutting down. When the rate of temperature drop in evaporation, Q, is greater than the first danger threshold but less than or equal to the second danger threshold (-m1℃ / min < Q ≤ -m2℃ / min), the electronic expansion valve will activate twice. When the rate of temperature drop in evaporation, Q, is greater than the second danger threshold (Q > -m2℃ / min), the electronic expansion valve will activate three times. The first danger threshold is less than the second danger threshold. This method effectively controls the electronic expansion valve to regulate the system when the pressure is too low, while also reducing the problem of poor accuracy in electronic expansion valve regulation. It also effectively prevents the unit from triggering low-pressure protection or emergency shutdown, improving the overall reliability and stability of the system.

[0035] Figure 3 This is the control flowchart for the electronic expansion valve when the system pressure is too low. When the system pressure is determined to be too low, and it can operate n times within one adjustment cycle, the opening of the electronic expansion valve is first increased by k%, then timing begins. Within each adjustment time cycle T, the valve operates once every t seconds, for a total of n adjustment actions. Then, the electronic expansion valve exits the low-pressure control, and the adjustment ends. The interval t can be evenly distributed.

[0036] Figure 4 This is a complete flowchart of an embodiment of the control method of the present invention. In this embodiment, the automatic control method for the electronic expansion valve includes the following steps: S1. The refrigeration equipment is started and the system initializes; S2. After the refrigeration system has been running for a period of time, determine whether the refrigeration system is in a state of low pressure. S3. When the refrigeration system is not in a low-pressure state, the electronic expansion valve adjusts in the normal way, that is, it only operates once for each adjustment; when the refrigeration system is in a low-pressure state, it enters the low-pressure control mode of the electronic expansion valve. S4. After entering the low pressure regulation, select the number of times to regulate each time according to the degree of low pressure. When the regulation is selected n times, first open the electronic expansion valve by k%, and then start timing. Within the time period T of each regulation, the operation is performed once every t seconds, and a total of n regulation operations are completed. S5. Determine whether the system evaporation temperature drop rate Q is greater than the set value -m℃ / min. If yes, clear the number of times n and the adjustment time period T of the electronic expansion valve adjustment and exit this adjustment. If no, return to step S4 and repeat the above low pressure adjustment steps according to the low pressure condition.

[0037] The automatic adjustment and control method for the electronic expansion valve proposed in this invention can be applied to refrigeration equipment such as air conditioners and refrigerators. Refrigeration equipment generally includes a compressor, condenser, electronic expansion valve, and evaporator. The refrigerant is compressed into a high-temperature, high-pressure gas by the compressor, cooled into a high-pressure, medium-temperature liquid by the condenser, and then throttled by the electronic expansion valve to become a low-temperature, low-pressure liquid. It then enters the evaporator to exchange heat with air or water, absorbing heat and evaporating into a low-temperature, low-pressure gas, before returning to the compressor in a cycle. The low pressure in the refrigeration equipment occurs in the evaporator, and the temperature and pressure on the low-pressure side can be detected by temperature or pressure sensors. When the control system detects excessively low pressure in the evaporator, the automatic control method for the electronic expansion valve proposed in this invention can effectively solve the problem of delayed system response caused by untimely low-pressure control adjustment within the unit; effectively solve the problem of large adjustment deviations often occurring with single adjustments; and improve the electronic expansion valve's synchronization issues through multiple adjustments, achieving precise adjustment. The adjustment time can be reasonably set and synchronized with the system response time, effectively improving the unit's lifespan. It effectively utilizes the throttling and pressure-reducing function of the electronic expansion valve, improving system stability and user experience through low-pressure control, while simultaneously enhancing the cooling effect.

[0038] The parameters mentioned in this manual, including the setpoint - m℃ / min, adjustment time period T, number of actions n, a, b, c, first danger threshold - m1 / min, second danger threshold - m2 / min, interval time t, and opening degree k%, are all calibration values ​​related to the experiment.

[0039] Since there is a correlation between temperature and pressure, as an alternative, the criterion for determining the excessively low pressure state can also be: the system evaporation pressure decrease rate X is less than or equal to a set value of hPa / min. X ≤ hPa / min. Considering that a negative evaporation pressure drop rate can easily be mistaken for a vacuum state, the value is set to the absolute value of the calculated result.

[0040] like Figure 5 As shown, when using the rate of decrease in evaporation pressure as a criterion for determining whether the system is under excessively low pressure conditions, the control method proposed in this invention includes the following steps: Determine if the refrigeration system is in a low-pressure state; When the system evaporation pressure drop rate X is less than or equal to the set value, and X≤hPa / min, the refrigeration system is in a low-pressure state. The electronic expansion valve is controlled to automatically adjust according to the low-pressure state. The electronic expansion valve is controlled to select different numbers of actions within an adjustment time cycle according to the degree of the low-pressure state. When the system evaporation pressure drop rate X is greater than the set value, and X > hPa / min, the refrigeration system low pressure is in a normal state, and the electronic expansion valve is adjusted according to the normal control method, achieving the desired result in one step.

[0041] Although pressure can also reflect situations where the pressure is too low, it is more appropriate to use the rate of change of evaporation temperature, as it can reflect not only the changes in pressure inside the evaporator, but also the relationship between temperature and pressure changes in the entire system.

[0042] The automatic adjustment and control method for the electronic expansion valve proposed in this invention can be programmed into software and stored in a computer storage medium. When the computer calls the software stored in the storage medium, it can execute the automatic control method for the electronic expansion valve proposed in this invention to control the operation of the refrigeration system. Therefore, the computer storage medium installed with the ability to execute the automatic control method for the electronic expansion valve proposed in this invention should also be covered within the scope of protection of the claims of this invention.

[0043] The above description is merely a specific embodiment of the present invention. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and variations within the spirit and framework of the present invention, and these modifications, equivalent substitutions, and variations should all be included within the protection scope of the claims of the present invention.

Claims

1. An automatic adjustment and control method for an electronic expansion valve, characterized in that, The steps include: determining whether the refrigeration system is in a low-pressure state; if not, adjusting the electronic expansion valve to the correct position in one step. If so, within an adjustment time period T, the electronic expansion valve is automatically adjusted according to the degree of low system pressure by different number of actions, and the opening of the electronic expansion valve is adjusted within each adjustment action. The adjustment time period T is selected based on the ambient temperature, the rate of decrease of the evaporation temperature, and the compressor operating frequency. Different operating conditions correspond to different adjustment time periods.

2. The automatic adjustment and control method for the electronic expansion valve as described in claim 1, characterized in that, The condition for determining the low-pressure state is: the rate of decrease of the system evaporation temperature is less than or equal to the set value of the rate of decrease of the evaporation temperature.

3. The automatic adjustment and control method for the electronic expansion valve as described in claim 1, characterized in that, When the refrigeration system is in a low-pressure state and needs to be activated n times within an adjustment time period, first increase the opening of the electronic expansion valve by k%, and then activate it once every time interval t. After completing n activations, determine whether the rate of decrease of the system evaporating temperature is greater than the set value. If so, reset the number of activations of the electronic expansion valve and the adjustment time period T to zero and exit this adjustment. If not, repeat the above adjustment according to the condition of meeting the low-pressure condition.

4. The automatic adjustment and control method for the electronic expansion valve as described in claim 3, characterized in that, The time t is evenly distributed according to the number of actions.

5. The automatic adjustment and control method for the electronic expansion valve as described in claim 3, characterized in that, The number of different actions, n, is greater than or equal to 1 and less than or equal to 3.

6. The automatic adjustment and control method for an electronic expansion valve as described in claim 1, characterized in that, Within each adjustment time period T, a first danger threshold and a second danger threshold are given for the rate of evaporation temperature decrease. The first danger threshold is less than the second danger threshold. When the rate of evaporation temperature decrease is less than or equal to the first danger threshold, the electronic expansion valve operates a times. When the rate of evaporation temperature decrease is greater than the first danger threshold and less than or equal to the second danger threshold, the electronic expansion valve operates b times. When the rate of evaporation temperature decrease is greater than the second danger threshold, the electronic expansion valve operates c times.

7. The automatic adjustment and control method for an electronic expansion valve as described in claim 6, characterized in that, The first danger threshold and the second danger threshold are set by ambient temperature, evaporation temperature change rate, and compressor operating frequency.

8. The automatic adjustment and control method for an electronic expansion valve as described in claim 6, characterized in that, The parameters a is 1st, b is 2nd, and c is 3rd.

9. An electronic expansion valve, characterized in that, The electronic expansion valve operates using the automatic adjustment and control method for electronic expansion valves as described in any one of claims 1-8.

10. A refrigeration device, characterized in that, The electronic expansion valve of the refrigeration equipment operates using the automatic adjustment and control method for the electronic expansion valve as described in any one of claims 1-8.

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