WO2021190235A1

WO2021190235A1 - Control method and system for flow of refrigerant of air conditioner

Info

Publication number: WO2021190235A1
Application number: PCT/CN2021/077887
Authority: WO
Inventors: 刘守宇; 熊长友; 郭成才
Original assignee: 青岛海尔空调电子有限公司; 海尔智家股份有限公司
Priority date: 2020-03-26
Filing date: 2021-02-25
Publication date: 2021-09-30
Also published as: CN113446702B; CN113446702A

Abstract

A control method and system for the flow of the refrigerant of air conditioner. The method comprises: step S1: in the heating mode of an air conditioner, measuring, in real time, the ambient temperature of an outdoor unit in the air conditioner and the temperature of the bottom of a compressor; step S2: determining whether the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold, and whether the temperature of the bottom of the compressor is less than or equal to a preset second temperature threshold; if yes, proceeding to step S3; if not, proceeding to step S4; step S3: decreasing the opening degree of an electronic expansion valve located on the refrigerant entrance side of an evaporator in the outdoor unit to reduce the flow of a refrigerant entering the evaporator, and then proceeding to step S2; and step S4: adjusting the opening degree of the electronic expansion valve according to the comparison result of the actual value of the suction gas superheat of the compressor and the preset target value of the suction has superheat to adjust the flow of the refrigerant entering the evaporator, and then proceeding to step S2. In the method, according to a heating state, different flow adjustment strategies are selected to adjust the flow of the refrigerant entering the evaporator, so as to ensure that in the heating process of the air conditioner, generation of a large amount of liquid refrigerant at the bottom of the compressor and suctioning into the compressor are avoided.

Description

Refrigerant flow control method and system of air conditioner

Technical field

The invention relates to the technical field of air conditioning control, in particular to a method and system for controlling the flow of refrigerant of an air conditioner.

Background technique

Compressor liquid return refers to the phenomenon that there is liquid refrigerant at the compressor suction port due to excessive refrigerant flow, evaporator failure, and excessive opening of the throttle device of the refrigerant pipeline. When there is liquid refrigerant at the compressor suction port In the case of refrigerant, these liquid refrigerants are easily sucked into the compressor and damage the internal components of the compressor.

At present, the existing compressor liquid return detection method mainly judges whether the compressor liquid return occurs based on the compressor suction superheat. If the suction superheat is lower than a certain value (such as 0), the compressor suction is determined Liquid refrigerant exists in the mouth. However, this method cannot detect whether there is liquid refrigerant at the bottom of the compressor, and when there is liquid refrigerant at the bottom of the compressor, these liquid refrigerants are also easily sucked into the compressor, thereby damaging the internal components of the compressor. For example: in the winter air conditioning heating, especially in the process of low-temperature heating, due to the low outdoor environment temperature, the temperature of the evaporator body can easily drop below the freezing temperature when the evaporator absorbs heat, causing frost on the surface of the evaporator/ Ice, which in turn causes the evaporation capacity of the evaporator to decrease, and the superheat of the low-temperature gas refrigerant output by the evaporator decreases. In addition, due to the rapid heat loss of the gas refrigerant in a low temperature environment, part of the gas refrigerant will liquefy or part of the liquid refrigerant will not be It evaporates into gaseous refrigerant and then flows into the bottom of the compressor, while the remaining gaseous refrigerant normally enters the compressor suction port and the compressor suction superheat will not change significantly. If the air conditioner is operated for a long time under low temperature heating , There will be more and more liquid refrigerant at the bottom of the compressor. This part of the liquid refrigerant will be easily sucked from the bottom of the compressor to the suction port. However, because the suction superheat of the compressor has not changed significantly, the existing compression The machine liquid back detection method not only fails to detect the presence of liquid refrigerant at the bottom of the compressor, but also fails to detect that the compressor has liquid back when the liquid refrigerant at the bottom of the compressor is sucked into the suction port of the compressor.

Summary of the invention

In order to overcome the above drawbacks, the present invention is proposed to provide a refrigerant flow control method and system for an air conditioner that solves or at least partially solves the problems of how to accurately detect whether there is liquid refrigerant at the bottom of the compressor and how to prevent liquid back from the compressor.

In a first aspect, there is provided a refrigerant flow control method for an air conditioner, the method including:

Step S1: In the heating mode of the air conditioner, real-time detection of the ambient temperature of the outdoor unit in the air conditioner and the temperature of the bottom of the compressor;

Step S2: Determine whether the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold, and whether the bottom temperature of the compressor is less than or equal to a preset second temperature threshold; if yes, go to step S3; if not , Then go to step S4;

Step S3: Decrease the opening degree of the electronic expansion valve located on the refrigerant inlet side of the evaporator in the outdoor unit to reduce the flow of refrigerant flowing into the evaporator, and then go to step S2;

Step S4: Adjust the opening of the electronic expansion valve according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat to adjust the refrigerant flow into the evaporator, and then Go to step S2.

Wherein, the step of "reducing the opening degree of the electronic expansion valve located on the inlet side of the evaporator refrigerant in the outdoor unit" specifically includes:

Within a certain period of time, the opening degree of the electronic expansion valve is gradually reduced according to the preset number of opening adjustment steps and the preset adjustment period.

Wherein, the step of "adjusting the opening of the electronic expansion valve according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat" specifically includes:

Obtaining the target value A and the adjustment period T of the opening adjustment step number of the electronic expansion valve according to the actual value of the suction superheat and the preset target value of the suction superheat, specifically includes:

Calculate the target value A of the opening adjustment step number according to the method shown in the following formula:

A=|Tsh-Tsh0|

Determine whether the opening adjustment step number target value A is greater than or equal to a preset step number threshold; if yes, set the adjustment period T to the preset first adjustment period; if not, set the adjustment period Is the preset second adjustment period;

Adjust the opening degree of the electronic expansion valve according to the comparison result of the actual value of the suction superheat degree and the preset target value of the suction superheat degree, as well as the opening degree adjustment step number target value A and the adjustment period T, Specifically:

If Tsh>Tsh0, the opening degree of the electronic expansion valve is successively increased according to the opening degree adjustment step number target value A and the adjustment period T within a certain period of time;

If Tsh<Tsh0, the opening degree of the electronic expansion valve is successively decreased according to the opening degree adjustment step number target value A and the adjustment period T within a certain period of time;

If Tsh=Tsh0, the opening degree of the electronic expansion valve is not adjusted;

Wherein, the Tsh and Tsh0 are the actual value of the suction superheat and the preset target value of the suction superheat, respectively, and the preset first adjustment period is smaller than the preset second adjustment period.

Wherein, the method further includes calculating the actual value of the suction superheat of the compressor according to the method shown in the following formula:

Tsh=Ts-min[Te, TC]

The Tsh is the actual value of the suction superheat of the compressor, the Ts is the actual value of the suction temperature of the compressor, and the Te and TC are along the evaporator in the outdoor unit. The temperature of the bottom coil of the outdoor unit and the temperature of the middle coil of the outdoor unit in the upper direction, "min" represents the minimum value function; and/or,

The method further includes a second temperature threshold obtaining step, and the second temperature threshold step specifically includes: real-time detection of the exhaust pressure of the compressor in the air conditioner, and obtaining the exhaust gas based on the corresponding relationship between the preset pressure and the saturation temperature For the saturation temperature corresponding to the pressure, the second temperature threshold is set according to the saturation temperature; or the second temperature threshold is obtained according to the method shown in the following formula:

Tthr=Tm+Tbc

The Tthr is the preset second temperature threshold, the Tm is the indoor unit coil temperature of the air conditioner detected in real time, and the Tbc is the preset temperature compensation value.

Wherein, before proceeding to step S3, the method further includes:

It is determined whether the operating time of the air conditioner in the heating mode reaches a preset time threshold; if so, go to step S3.

In a second aspect, there is provided a refrigerant flow control system for an air conditioner, the system including:

The temperature acquisition module is configured to detect the ambient temperature of the outdoor unit in the air conditioner and the bottom temperature of the compressor in real time in the heating mode of the air conditioner;

A temperature judgment module configured to judge whether the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold, and whether the bottom temperature of the compressor is less than or equal to a preset second temperature threshold; A flow adjustment module; if not, start the second flow adjustment module;

The first flow adjustment module is configured to reduce the opening degree of the electronic expansion valve located on the inlet side of the evaporator refrigerant in the outdoor unit to reduce the flow rate of the refrigerant flowing into the evaporator, and then restart the environment Temperature judgment module;

The second flow adjustment module is configured to adjust the opening of the electronic expansion valve according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat to adjust the inflow The refrigerant flow rate of the evaporator, and then the ambient temperature judgment module is restarted.

Wherein, the first flow adjustment module is configured to perform the following operations:

Wherein, the second flow adjustment module is configured to perform the following operations:

A=|Tsh-Tsh0|

If Tsh>Tsh0, the opening degree of the electronic expansion valve is successively increased within a certain period of time according to the opening degree adjustment step number target value A and the adjustment period T;

The Tsh and Tsh0 are respectively the actual value of the suction superheat and the preset target value of the suction superheat, and the preset first adjustment period is smaller than the preset second adjustment period.

Wherein, the second flow adjustment module is configured to calculate the actual value of the suction superheat of the compressor according to the method shown in the following formula:

Tsh=Ts-min[Te, TC]

The temperature judgment module is configured to perform the following operations: detect the discharge pressure of the compressor in the air conditioner in real time, obtain the saturation temperature corresponding to the discharge pressure based on the corresponding relationship between the preset pressure and the saturation temperature, and obtain the saturation temperature corresponding to the discharge pressure according to the saturation Set the second temperature threshold for temperature; or obtain the second temperature threshold according to the method shown in the following formula:

Tthr=Tm+Tbc

Wherein, the first flow adjustment module is configured to: when the temperature judgment module judges that the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold, and the bottom temperature of the compressor is less than or equal to a preset second temperature After the threshold, continue to determine whether the operating time of the air conditioner in the heating mode reaches the preset time threshold; if so, reduce the opening of the electronic expansion valve on the refrigerant inlet side of the evaporator in the outdoor unit to reduce the inflow The refrigerant flow rate of the evaporator, and then the ambient temperature judgment module is restarted.

The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

In the technical solution of the present invention, when the air conditioner is heating, the heating state of the air conditioner is first analyzed according to the ambient temperature of the outdoor unit and the temperature at the bottom of the compressor, and then different refrigerant flow adjustment methods are adopted according to different heating states. Adjust the flow rate of the refrigerant flowing into the evaporator to prevent the liquid refrigerant at the bottom of the compressor from accumulating and being sucked into the compressor. Specifically, when the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold, it indicates that the outdoor ambient temperature is low and the air conditioner is in a low-temperature heating state. When the ambient temperature of the outdoor unit is greater than the preset first temperature threshold, it indicates that the outdoor ambient temperature is not very low, and the air conditioner is in a normal heating state. Since the lower the outdoor ambient temperature, the more liquid refrigerant will be produced at the bottom of the compressor. Therefore, compared to the conventional heating state, more liquid refrigerant will be produced at the bottom of the compressor during low-temperature heating. Over time, the liquid refrigerant at the bottom of the compressor will accumulate and be sucked into the compressor. After detecting that the ambient temperature of the outdoor unit is greater than the preset first temperature threshold (normal heating state), the present invention adjusts according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat The opening degree of the electronic expansion valve is used to adjust the flow of refrigerant into the evaporator. After detecting that the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold (low temperature heating state), according to the comparison result of the bottom temperature of the compressor and the preset second temperature threshold, it is determined whether the bottom of the compressor has been generated Liquid refrigerant. Wherein, the preset second temperature threshold is set according to the temperature of the indoor unit coil. If the temperature at the bottom of the compressor is less than or equal to the preset second temperature threshold, it indicates that the temperature at the bottom of the compressor is less than or equal to the temperature of the refrigerant in the condenser of the indoor unit, and there is already liquid refrigerant at the bottom of the compressor. The throttle device on the refrigerant inlet side, such as the opening degree of an electronic expansion valve, reduces the refrigerant flow into the evaporator and prevents the liquid refrigerant at the bottom of the compressor from further increasing. If the temperature at the bottom of the compressor is greater than the preset second temperature threshold, indicating that no liquid refrigerant is produced at the bottom of the compressor, the same flow adjustment method as the conventional heating state can be used to adjust the flow of refrigerant flowing into the evaporator. Through the above method, it can be ensured that during the heating process of the air conditioner, a large amount of liquid refrigerant will not be generated at the bottom of the compressor and be sucked into the compressor, damaging the internal components of the compressor.

Description of the drawings

The specific embodiments of the present invention are described below with reference to the accompanying drawings, in which:

Fig. 1 is a schematic flow diagram of main steps of a method for controlling refrigerant flow of an air conditioner according to an embodiment of the present invention;

2 is a schematic diagram of the main structure of a refrigerant flow control system of an air conditioner according to an embodiment of the present invention;

Figure 3 is a schematic diagram of an application scenario of the present invention;

List of reference signs:

11: temperature acquisition module; 12: temperature judgment module; 13: first flow adjustment module; 14: second flow adjustment module; 21: compressor; 211: first temperature sensor; 212: second temperature sensor; 22: condensation 221: third temperature sensor; 23: evaporator; 231: fourth temperature sensor; 232: fifth temperature sensor; 24: throttling device; 25: four-way valve.

Detailed ways

Hereinafter, some embodiments of the present invention will be described with reference to the drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention, and are not intended to limit the protection scope of the present invention.

In the description of the present invention, "module" may include hardware, software or a combination of both. A module can include hardware circuits, various suitable sensors, communication ports, and memory, and can also include software parts, such as program codes, or a combination of software and hardware. The term "A and/or B" means all possible combinations of A and B, such as only A, only B, or A and B. The term "at least one of A or B" or "at least one of A and B" has a meaning similar to "A and/or B" and may include only A, only B, or A and B. The terms "a" and "this" in the singular form may also include the plural form.

A part of the terms of the present invention will be explained.

Refrigerant refers to a substance that transfers heat energy through evaporation and condensation. For example, the refrigerant may be freon, alkane, ammonia, or the like.

The indoor unit coil temperature refers to the coil temperature of the coil condenser in the indoor unit of the air conditioner. The coil temperature is close to the temperature of the refrigerant flowing in the coil condenser.

The bottom coil temperature of the outdoor unit refers to the temperature of the lower evaporator coil in the bottom-up direction of the coil evaporator in the outdoor unit. The temperature of the middle coil of the outdoor unit refers to the temperature of the evaporator coil located in the middle in the bottom-up direction of the coil evaporator in the outdoor unit.

In the heating mode of the air conditioner, the low-temperature and low-pressure refrigerant output from the evaporator in the outdoor unit is compressed by the compressor into a high-temperature and high-pressure gaseous refrigerant and output to the condenser of the indoor unit through the refrigerant pipeline. The high-temperature and high-pressure gaseous refrigerant is condensed The condenser releases heat to achieve the purpose of heating, and then the low-temperature and low-pressure liquid refrigerant output from the condenser flows into the evaporator through the refrigerant pipeline and evaporates into a low-temperature and low-pressure gaseous refrigerant and then flows into the compressor. When the refrigerant flow rate at the inlet of the evaporator is too large or the evaporator fails to reduce its evaporating capacity, it will cause the evaporator to output a part of the liquid refrigerant. If this part of the liquid refrigerant is sucked into the compressor, it will damage the inside of the compressor. member. In order to detect the presence of liquid refrigerant (liquid return) at the compressor suction port in time, the traditional detection method in the prior art is to determine whether compressor liquid return occurs based on the compressor suction superheat. If the suction superheat is lower than With a certain value (such as 0), it is determined that there is liquid refrigerant at the suction port of the compressor. However, this method cannot detect whether there is liquid refrigerant at the bottom of the compressor, and when there is liquid refrigerant at the bottom of the compressor, these liquid refrigerants are also easily sucked into the compressor, thereby damaging the internal components of the compressor. Specifically, in the winter air conditioner heating, especially in the process of low-temperature heating, because the outdoor environment temperature is low, the temperature of the evaporator body can easily drop below the freezing temperature when the evaporator absorbs heat, resulting in the surface of the evaporator. Frost/ice causes the evaporator's evaporating capacity to decrease, and the superheat of the low-temperature gaseous refrigerant output by the evaporator decreases. In addition, due to the rapid heat loss of the gaseous refrigerant in a low temperature environment, part of the gaseous refrigerant output from the evaporator will liquefy Or part of the liquid refrigerant is not evaporated into gaseous refrigerant, and then flows into the bottom of the compressor, while the remaining gaseous refrigerant normally enters the compressor suction port, and the compressor suction superheat will not change significantly. If the air conditioner is in Running for a long time under low temperature heating, there will be more and more liquid refrigerant at the bottom of the compressor. This part of the liquid refrigerant will be easily sucked from the bottom of the compressor to the suction port, but the suction superheat of the compressor does not occur too much. Therefore, the existing compressor liquid return detection method not only cannot detect the presence of liquid refrigerant at the bottom of the compressor, but also cannot detect that the compressor has returned when the liquid refrigerant at the bottom of the compressor is sucked into the suction port of the compressor. liquid.

In the embodiment of the present invention, when the air conditioner is heating, the heating state of the air conditioner is first analyzed according to the ambient temperature of the outdoor unit and the temperature at the bottom of the compressor, and then different refrigerant flow adjustment methods are used to adjust the inflow according to different heating states. The refrigerant in the evaporator prevents the liquid refrigerant at the bottom of the compressor from accumulating and being sucked into the compressor. Specifically, when the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold (for example: -5°C), it indicates that the outdoor ambient temperature is low and the air conditioner is in a low-temperature heating state. When the ambient temperature of the outdoor unit is greater than the preset first temperature threshold (for example: -5°C), it indicates that the outdoor ambient temperature is not very low, and the air conditioner is in a conventional heating state. From the foregoing analysis, it can be seen that the lower the outdoor ambient temperature, the more liquid refrigerant will be produced at the bottom of the compressor. Therefore, compared with conventional heating conditions, more liquid refrigerant will be produced at the bottom of the compressor during low-temperature heating. When running for a long time in a hot state, the liquid refrigerant at the bottom of the compressor will accumulate and be sucked into the compressor. After detecting that the ambient temperature of the outdoor unit is greater than the preset first temperature threshold (normal heating state), the present invention adjusts according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat The opening degree of the electronic expansion valve is used to adjust the flow of refrigerant into the evaporator. After detecting that the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold (low temperature heating state), according to the comparison result of the bottom temperature of the compressor and the preset second temperature threshold, it is determined whether the bottom of the compressor has been generated Liquid refrigerant. If the temperature at the bottom of the compressor is less than or equal to the preset second temperature threshold, it indicates that the temperature at the bottom of the compressor is less than or equal to the temperature of the refrigerant in the indoor unit condenser (indoor unit coil temperature), and there is already liquid refrigerant at the bottom of the compressor. The opening of the electronic expansion valve on the refrigerant inlet side of the evaporator in the outdoor unit is reduced to reduce the flow of refrigerant flowing into the evaporator and prevent the liquid refrigerant at the bottom of the compressor from further increasing. If the temperature at the bottom of the compressor is greater than the preset second temperature threshold, indicating that the bottom of the compressor has not produced liquid refrigerant, the same flow adjustment method as the conventional heating state can be used to adjust the flow of refrigerant into the evaporator (according to the compressor’s The comparison result of the actual value of the suction superheat degree and the preset target value of the suction superheat degree adjusts the opening degree of the electronic expansion valve to adjust the refrigerant flow into the evaporator).

Refer to Figure 3, which is a schematic diagram of an application scenario of the present invention. As shown in FIG. 3, the outdoor unit of the air conditioner includes a compressor 21, an evaporator 23, a throttling device 24 (such as an electronic expansion valve), and a four-way valve 25. The compressor bottom 21 is provided with a first temperature sensor 211, and the first temperature sensor 211 is used to detect the temperature of the compressor bottom. A second temperature sensor 212 is provided at the suction port of the bottom 21 of the compressor, and the second temperature sensor 212 is used to detect the temperature at the suction port of the compressor. A fifth temperature sensor 232 and a fourth temperature sensor 231 are respectively arranged in the bottom-up direction along the evaporator 23. The fifth temperature sensor 232 is used to detect the temperature of the evaporator coil at the bottom of the outdoor unit (the bottom coil of the outdoor unit). Temperature), the fourth temperature sensor 231 is used to detect the temperature of the evaporator coil in the middle of the outdoor unit (the temperature of the middle coil of the outdoor unit). The indoor unit of the air conditioner includes a condenser 22, the condenser 22 is provided with a third temperature sensor 221, and the third temperature sensor 221 is used to detect the coil temperature of the condenser 22 (indoor unit coil temperature). When the air conditioner is in heating operation, it first obtains the temperature detected by each sensor and the outdoor ambient temperature, analyzes the heating state of the air conditioner according to the obtained temperature, and then adopts different refrigerant flow adjustment methods to adjust the section according to different heating states. The flow device 24, such as the opening degree of an electronic expansion valve, adjusts the flow rate of the refrigerant flowing into the evaporator to prevent the compressor from sucking in the liquid refrigerant and damaging the compressor.

Referring to FIG. 1, FIG. 1 is a schematic flow diagram of main steps of a method for controlling the flow of refrigerant of an air conditioner according to an embodiment of the present invention. As shown in Fig. 1, the refrigerant flow control method of the air conditioner in the embodiment of the present invention mainly includes the following steps:

Step S101: In the heating mode of the air conditioner, the ambient temperature of the outdoor unit in the air conditioner and the temperature of the bottom of the compressor are detected in real time.

In this embodiment, the outdoor unit of the air conditioner is provided with sensors for detecting the ambient temperature and the bottom temperature of the compressor, and the ambient temperature of the outdoor unit and the bottom temperature of the compressor can be obtained by acquiring the temperature detection data of these sensors.

Step S102: Determine whether the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold. If the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold, indicating that the air conditioner is in a low-temperature heating state, then go to step S103. If the ambient temperature of the outdoor unit is greater than the preset first temperature threshold, indicating that the air conditioner is in a normal heating state, then go to step S105.

Since the evaporation capacity of different types of evaporators is affected by temperature to different degrees, different preset first temperature thresholds can be set according to different types of evaporators. An example: testing the icing/frosting degree of different types of evaporators under different temperature environments, and then selecting a temperature with the icing/frosting degree greater than a certain value as the first temperature threshold according to the test result. In this embodiment, the first temperature threshold may be -5°C.

In one embodiment, after judging whether the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold, the step of judging the operation time of the air conditioner is further included. The air conditioner operating time judging step specifically includes: judging whether the operating time of the air conditioner in the heating mode reaches a preset time threshold; if the operating time reaches the preset time threshold, go to step S103. If the running time does not reach the preset time threshold, continue to determine whether the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold. An example: the preset time threshold is 10 minutes.

Step S103: Determine whether the bottom temperature of the compressor is less than or equal to a preset second temperature threshold. If the temperature at the bottom of the compressor is less than or equal to the preset second temperature threshold, indicating that there is liquid refrigerant at the bottom of the compressor, then go to step S104. If the temperature at the bottom of the compressor is greater than the preset second temperature threshold, indicating that there is no liquid refrigerant at the bottom of the compressor, go to step S105.

In one embodiment, if a device for detecting the discharge pressure of the compressor, such as a discharge pressure sensor, is provided in the air conditioner, the second temperature threshold can be obtained according to the following steps: real-time detection of the discharge pressure of the compressor in the air conditioner, The saturation temperature corresponding to the exhaust pressure is acquired based on the preset corresponding relationship between the pressure and the saturation temperature, and the second temperature threshold is set according to the saturation temperature. An example: the second temperature threshold is equal to or close to the saturation temperature. Saturation temperature (saturation temperature) refers to the temperature that liquid and gas have when they are in dynamic equilibrium. When the saturation temperature must be the corresponding gas pressure, it is also certain. The present invention uses this relationship and the compressor discharge detected in real time. The gas pressure obtains the corresponding saturation temperature, and then sets the second temperature threshold according to the saturation temperature. The "correspondence between preset pressure and saturation temperature" can be obtained by testing the saturation temperature under different pressures.

In one embodiment, if the air conditioner is not provided with a device for detecting the discharge pressure of the compressor, such as a discharge pressure sensor, the preset second temperature threshold can be obtained according to the method shown in the following formula (1):

Tthr=Tm+Tbc (1)

The meaning of each parameter in formula (1) is: Tthr is the preset second temperature threshold, Tm is the indoor unit coil temperature, and Tbc is the preset temperature compensation value. The indoor unit coil temperature Tm can be detected by the third temperature sensor 221 shown in FIG. 3. The preset temperature compensation value Tbc is obtained by operating an air conditioner equipped with a compressor discharge pressure detection device and an indoor unit coil temperature detection device at the same time. Specifically, when controlling the operation of the air conditioner, the pressure detection result of the compressor discharge pressure detection device and the temperature detection result of the indoor unit coil temperature detection device are obtained, and then the pressure is obtained based on the corresponding relationship between the preset pressure and the saturation temperature. The saturation temperature corresponding to the detection result, and finally the temperature compensation value is set according to the difference between the saturation temperature and the temperature detection result. An example: the temperature compensation value is equal to or close to the difference. The "correspondence between preset pressure and saturation temperature" can be obtained by testing the saturation temperature under different pressures. In the embodiment of the present invention, if the air conditioner is not equipped with a device for detecting the discharge pressure of the compressor, such as a discharge pressure sensor, the temperature compensation value obtained through the above operation test can be directly called, and then the formula (1) The second temperature threshold is calculated.

Step S104: Decrease the opening degree of the electronic expansion valve located at the refrigerant inlet side of the evaporator in the outdoor unit to reduce the flow rate of the refrigerant flowing into the evaporator, and then go to step S102.

In one embodiment, reducing the opening degree of the electronic expansion valve located on the inlet side of the refrigerant inlet of the evaporator in the outdoor unit specifically includes: successively decreasing the number of steps and the preset adjustment period according to the preset opening degree within a certain period of time. The opening of the electronic expansion valve.

An example: the preset number of opening adjustment steps is 1 degree, the preset adjustment period is 30 seconds, and the certain duration is 60 seconds, when it is determined in step S103 that the bottom temperature of the compressor is less than or equal to the preset second temperature threshold After that, decrease the opening degree of the electronic expansion valve by 1 degree at the 0th, 30th, and 60th seconds, and return to step S103 at the 60th second to continue to determine whether the ambient temperature of the outdoor unit is less than or equal to the preset first A temperature threshold.

Step S105: Adjust the opening degree of the electronic expansion valve according to the comparison result of the compressor suction superheat actual value and the preset suction superheat target value to adjust the refrigerant flow into the evaporator, and then go to step S102.

In one embodiment, adjusting the opening degree of the electronic expansion valve according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat includes the following steps:

Step S1051: Obtain the opening adjustment step number target value A and the adjustment period T of the electronic expansion valve according to the actual suction superheat value and the preset suction superheat target value, which specifically includes:

Calculate the target value A of the opening adjustment step number according to the method shown in the following formula (2):

A=|Tsh-Tsh0| (2)

The meaning of each parameter in formula (2) is: Tsh and Tsh0 are the actual value of the suction superheat and the preset target value of the suction superheat, respectively.

Determine whether the opening adjustment step target value A is greater than or equal to the preset step threshold; if yes, set the adjustment period T to the preset first adjustment period; if not, set the adjustment period to the preset second Adjustment cycle. Wherein, the preset first adjustment period is less than the preset second adjustment period. An example: the preset step threshold is 3, the preset first adjustment period is 10 seconds, and the preset second adjustment period is 30 seconds. If A≥3, set the adjustment period T=10 seconds, that is, adjust the opening of the electronic expansion valve every 10 seconds. If 0<A<3, set the adjustment period T=30 seconds, that is, adjust the opening of the electronic expansion valve every 30 seconds.

In an embodiment, the actual value of the suction superheat of the compressor can be calculated according to the method shown in the following formula (3):

Tsh=Ts-min[Te, TC] (3)

The meaning of each parameter in formula (3) is: Tsh is the actual value of the suction superheat of the compressor, Ts is the actual value of the suction temperature of the compressor, Te and TC are respectively along the evaporator in the outdoor unit from bottom to top The temperature of the bottom coil of the outdoor unit and the temperature of the middle coil of the outdoor unit in the direction, "min" represents the minimum value function. The actual value of the suction temperature of the compressor can be detected by the second temperature sensor 212 shown in FIG. 3.

Step S1052: Adjust the opening degree of the electronic expansion valve according to the comparison result of the actual suction superheat value and the preset suction superheat target value, as well as the opening adjustment step number A and the adjustment period T, which specifically include:

If Tsh>Tsh0, the opening degree of the electronic expansion valve is gradually increased according to the opening degree adjustment target value A and the adjustment period T within a certain period of time. If Tsh<Tsh0, the opening degree of the electronic expansion valve is gradually reduced according to the opening degree adjustment target value A and the adjustment period T within a certain period of time. If Tsh=Tsh0, the opening degree of the electronic expansion valve is not adjusted.

An example: the preset step threshold is 3, the preset first adjustment period is 10 seconds, the preset second adjustment period is 30 seconds, and the certain duration is 60 seconds. If Tsh>Tsh0 and |Tsh-Tsh0|≥3 (A≥3), when step S102 determines that the ambient temperature of the outdoor unit is greater than the preset first temperature threshold, or step S103 determines that the bottom temperature of the compressor is greater than the preset first temperature threshold. After the second temperature threshold, increase the opening degree of the A degree electronic expansion valve at the 0th, 10th, 20th, 30th, 40th, 50th and 60th seconds respectively, and return to step S102 at the 60th second to continue to judge the ambient temperature of the outdoor unit Whether it is less than or equal to the preset first temperature threshold.

It should be pointed out that although the various steps are described in a specific sequence in the above embodiments, those skilled in the art can understand that in order to achieve the effects of the present invention, different steps do not have to be executed in this order. They can be executed simultaneously (parallel) or in other sequences, and these changes are all within the protection scope of the present invention.

Referring to Figure 2, Figure 2 is a schematic diagram of the main structure of a refrigerant flow control system for an air conditioner according to an embodiment of the present invention. As shown in FIG. 2, the refrigerant flow control system of the air conditioner in the embodiment of the present invention mainly includes a temperature acquisition module 11, a temperature judgment module 12, a first flow adjustment module 13 and a second flow adjustment module 14. In some embodiments, one or more of the temperature acquisition module 11, the temperature judgment module 12, the first flow adjustment module 13, and the second flow adjustment module 14 may be part of the processor. In some embodiments, these modules may respectively correspond to a part of electronic circuits in the processor for signal or data processing, and may also correspond to related program codes stored in a computer-readable medium (such as a memory). In some embodiments, one or more of the temperature acquisition module 11, the temperature judgment module 12, the first flow adjustment module 13, and the second flow adjustment module 14 may be combined into one module. In some embodiments, the temperature acquisition module 11 may be configured to detect the ambient temperature of the outdoor unit in the air conditioner and the bottom temperature of the compressor in real time in the heating mode of the air conditioner. The temperature determination module 12 may be configured to determine whether the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold, and whether the bottom temperature of the compressor is less than or equal to a preset second temperature threshold; if so, the first flow adjustment module is activated 13; if not, start the second flow adjustment module 14. The first flow adjustment module 13 may be configured to reduce the opening degree of the electronic expansion valve located at the refrigerant inlet side of the evaporator in the outdoor unit to reduce the flow of refrigerant flowing into the evaporator, and then restart the ambient temperature judgment module 12. The second flow adjustment module 14 may be configured to adjust the opening of the electronic expansion valve according to the comparison result of the actual value of the suction superheat of the compressor with the preset target value of the suction superheat, so as to adjust the flow of refrigerant flowing into the evaporator, Then start the ambient temperature judgment module 12 again. In an embodiment, the description of the specific realized functions can refer to the steps S101-S105.

In one embodiment, the first flow adjustment module 13 is configured to perform the following operations: within a certain period of time, the opening degree of the electronic expansion valve is successively decreased according to the preset number of opening adjustment steps and the preset adjustment period. In an embodiment, for the description of the specific realized functions, refer to the description in step S105.

In one embodiment, the second flow adjustment module 14 is configured to perform the following operations:

According to the actual value of the suction superheat and the preset target value of the suction superheat, obtaining the target value A of the opening adjustment step number and the adjustment period T of the electronic expansion valve specifically includes:

Calculate the opening adjustment step number target value A according to the method shown in formula (2), and judge whether the opening adjustment step number target value A is greater than or equal to the preset step number threshold; if so, set the adjustment period T as the preset The first adjustment period; if not, the adjustment period is set to the preset second adjustment period. Adjust the opening of the electronic expansion valve according to the comparison result of the actual suction superheat value and the preset suction superheat target value, as well as the opening adjustment step number target value A and the adjustment period T, including: if Tsh>Tsh0, Then within a certain period of time, the opening degree of the electronic expansion valve is gradually increased according to the opening degree target value A and the adjustment period T; if Tsh＜Tsh0, the step value A and the adjustment period are adjusted according to the opening degree within a certain period of time T decreases the opening degree of the electronic expansion valve successively; if Tsh=Tsh0, the opening degree of the electronic expansion valve is not adjusted; among them, Tsh and Tsh0 are the actual value of the suction superheat and the preset target value of the suction superheat, respectively. The preset first adjustment period is less than the preset second adjustment period. In an embodiment, for the description of the specific realized functions, refer to the description in step S105.

In an embodiment, the second flow adjustment module 14 may also be configured to calculate the actual value of the suction superheat of the compressor according to the method shown in formula (3). In an embodiment, for the description of the specific realized functions, refer to the description in step S105.

In one embodiment, the temperature judgment module 12 may also be configured to perform the following operations: detect the discharge pressure of the compressor in the air conditioner in real time, and obtain the saturation temperature corresponding to the discharge pressure based on the corresponding relationship between the preset pressure and the saturation temperature. , The second temperature threshold is set according to the saturation temperature; or the second temperature threshold is obtained according to the method shown in formula (1). In an embodiment, for the description of the specific realized functions, refer to the description in step S103.

In one embodiment, the first flow adjustment module 13 may also be configured to determine that when the temperature determination module determines that the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold, and the bottom temperature of the compressor is less than After it is equal to the preset second temperature threshold, continue to determine whether the operating time of the air conditioner in the heating mode reaches the preset time threshold; if so, reduce the electronic expansion valve located on the refrigerant inlet side of the evaporator in the outdoor unit The opening. In an embodiment, the description of specific functions can be found in steps S102-S104.

The above-mentioned refrigerant flow control system of the air conditioner is used to implement the embodiment of the refrigerant flow control method of the air conditioner shown in FIG. It can be clearly understood that, for the convenience and conciseness of the description, the specific working process and related descriptions of the refrigerant flow control system of the air conditioner can refer to the content described in the embodiment of the refrigerant flow control method of the air conditioner, which will not be repeated here. .

Those skilled in the art can understand that all or part of the process in the method of the above-mentioned embodiment of the present invention can also be completed by instructing relevant hardware through a computer program, and the computer program can be stored in a computer readable In the storage medium, when the computer program is executed by the processor, the steps of the foregoing method embodiments can be implemented. Wherein, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file, or some intermediate forms. The computer-readable medium may include: any entity or device, medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, and electrical carrier signal that can carry the computer program code. , Telecommunications signals and software distribution media, etc. It should be noted that the content contained in the computer-readable medium can be appropriately added or deleted according to the requirements of the legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to the legislation and patent practice, the computer-readable medium Does not include electrical carrier signals and telecommunication signals.

Furthermore, it should be understood that, since the setting of each module is only to illustrate the functional units of the system of the present invention, the physical devices corresponding to these modules may be the processor itself, or part of the software in the processor, part of the hardware, or Part of the combination of software and hardware. Therefore, the number of modules in the figure is only schematic.

Those skilled in the art can understand that each module in the system can be adaptively split or merged. Such splitting or merging of specific modules will not cause the technical solution to deviate from the principle of the present invention. Therefore, the technical solutions after splitting or merging will fall within the protection scope of the present invention.

The refrigerant flow control method of the air conditioner of the embodiment of the present invention first analyzes the heating state of the air conditioner according to the ambient temperature of the outdoor unit and the temperature of the bottom of the compressor when the air conditioner is heating, and then adopts different heating conditions according to different heating conditions. The refrigerant flow adjustment method adjusts the refrigerant flowing into the evaporator to prevent the liquid refrigerant at the bottom of the compressor from accumulating and being sucked into the compressor. Specifically, when the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold, it indicates that the outdoor ambient temperature is low and the air conditioner is in a low-temperature heating state. When the ambient temperature of the outdoor unit is greater than the preset first temperature threshold, it indicates that the outdoor ambient temperature is not very low, and the air conditioner is in a normal heating state. After detecting that the ambient temperature of the outdoor unit is greater than the preset first temperature threshold, the present invention adjusts the opening degree of the electronic expansion valve according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat , To adjust the flow of refrigerant into the evaporator. After detecting that the ambient temperature of the outdoor unit is less than or equal to the preset first temperature threshold, according to the comparison result of the bottom temperature of the compressor and the preset second temperature threshold, it is determined whether liquid refrigerant has been generated at the bottom of the compressor. Wherein, the preset second temperature threshold is set according to the temperature of the indoor unit coil. If the temperature at the bottom of the compressor is less than or equal to the preset second temperature threshold, it indicates that the temperature at the bottom of the compressor is less than or equal to the temperature of the refrigerant in the condenser of the indoor unit, and there is already liquid refrigerant at the bottom of the compressor. The opening of the electronic expansion valve on the refrigerant inlet side reduces the flow of refrigerant flowing into the evaporator and prevents the liquid refrigerant at the bottom of the compressor from further increasing. If the temperature at the bottom of the compressor is greater than the preset second temperature threshold, indicating that no liquid refrigerant is produced at the bottom of the compressor, the same flow adjustment method as the conventional heating state can be used to adjust the flow of the refrigerant flowing into the evaporator.

So far, the technical solution of the present invention has been described in conjunction with an embodiment shown in the drawings, but it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

A refrigerant flow control method for an air conditioner, characterized in that the method includes:

Step S1: In the heating mode of the air conditioner, real-time detection of the ambient temperature of the outdoor unit in the air conditioner and the temperature of the bottom of the compressor;

Step S2: Determine whether the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold, and whether the bottom temperature of the compressor is less than or equal to a preset second temperature threshold; if yes, go to step S3; if not , Then go to step S4;

Step S3: Decrease the opening degree of the electronic expansion valve located on the refrigerant inlet side of the evaporator in the outdoor unit to reduce the flow of refrigerant flowing into the evaporator, and then go to step S2;

Step S4: Adjust the opening of the electronic expansion valve according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat to adjust the refrigerant flow into the evaporator, and then Go to step S2.
The refrigerant flow control method of an air conditioner according to claim 1, wherein the step of "decreasing the opening degree of the electronic expansion valve on the refrigerant inlet side of the evaporator in the outdoor unit" specifically includes:

Within a certain period of time, the opening degree of the electronic expansion valve is gradually reduced according to the preset number of opening adjustment steps and the preset adjustment period.
The refrigerant flow control method of an air conditioner according to claim 1, wherein the electronic expansion is adjusted according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat. The steps of "valve opening" specifically include:

Obtaining the target value A and the adjustment period T of the opening adjustment step number of the electronic expansion valve according to the actual value of the suction superheat and the preset target value of the suction superheat, specifically includes:

Calculate the target value A of the opening adjustment step number according to the method shown in the following formula:

A=|Tsh-Tsh0|

Determine whether the opening adjustment step number target value A is greater than or equal to a preset step number threshold; if yes, set the adjustment period T to the preset first adjustment period; if not, set the adjustment period Is the preset second adjustment period;

Adjust the opening degree of the electronic expansion valve according to the comparison result of the actual value of the suction superheat degree and the preset target value of the suction superheat degree, as well as the opening degree adjustment step number target value A and the adjustment period T, Specifically:

If Tsh>Tsh0, the opening degree of the electronic expansion valve is successively increased within a certain period of time according to the opening degree adjustment step number target value A and the adjustment period T;

If Tsh<Tsh0, the opening degree of the electronic expansion valve is successively decreased according to the opening degree adjustment step number target value A and the adjustment period T within a certain period of time;

If Tsh=Tsh0, the opening degree of the electronic expansion valve is not adjusted;

Wherein, the Tsh and Tsh0 are the actual value of the suction superheat and the preset target value of the suction superheat, respectively, and the preset first adjustment period is smaller than the preset second adjustment period.
The refrigerant flow control method of an air conditioner according to claim 1, wherein the method further comprises calculating the actual value of the suction superheat of the compressor according to the method shown in the following formula:

Tsh=Ts-min[Te, TC]

Wherein, the Tsh is the actual value of the suction superheat of the compressor, the Ts is the actual value of the suction temperature of the compressor, and the Te and TC are respectively along the evaporator in the outdoor unit The temperature of the bottom coil of the outdoor unit and the temperature of the middle coil of the outdoor unit in the bottom-up direction, "min" represents the minimum value function; and/or,

The method further includes a second temperature threshold obtaining step, and the second temperature threshold step specifically includes real-time detection of the discharge pressure of the compressor in the air conditioner, and obtaining the discharge pressure based on the corresponding relationship between the preset pressure and the saturation temperature For the corresponding saturation temperature, the second temperature threshold is set according to the saturation temperature; or the second temperature threshold is obtained according to the method shown in the following formula:

Tthr=Tm+Tbc

Wherein, the Tthr is the preset second temperature threshold, the Tm is the indoor unit coil temperature in the air conditioner detected in real time, and the Tbc is the preset temperature compensation value.
The refrigerant flow control method of an air conditioner according to claim 1, characterized in that, before proceeding to step S3, the method further comprises:

It is determined whether the operating time of the air conditioner in the heating mode reaches a preset time threshold; if so, go to step S3.
A refrigerant flow control system for an air conditioner, characterized in that the system includes:

The temperature acquisition module is configured to detect the ambient temperature of the outdoor unit in the air conditioner and the bottom temperature of the compressor in real time in the heating mode of the air conditioner;

A temperature judgment module, which is configured to judge whether the ambient temperature of the outdoor unit is less than or equal to a preset first temperature threshold, and whether the bottom temperature of the compressor is less than or equal to a preset second temperature threshold; if so, the first temperature threshold is activated; A flow adjustment module; if not, start the second flow adjustment module;

The first flow adjustment module is configured to reduce the opening degree of the electronic expansion valve located on the inlet side of the evaporator refrigerant in the outdoor unit to reduce the flow rate of the refrigerant flowing into the evaporator, and then restart the environment Temperature judgment module;

The second flow adjustment module is configured to adjust the opening of the electronic expansion valve according to the comparison result of the actual value of the suction superheat of the compressor and the preset target value of the suction superheat to adjust the inflow The refrigerant flow rate of the evaporator, and then the ambient temperature judgment module is restarted.
The refrigerant flow control system of an air conditioner according to claim 6, further comprising: the first flow adjustment module is configured to perform the following operations:

Within a certain period of time, the opening degree of the electronic expansion valve is gradually reduced according to the preset number of opening adjustment steps and the preset adjustment period.
The refrigerant flow control system for an air conditioner according to claim 6, further comprising: the second flow adjustment module is configured to perform the following operations:

Obtaining the target value A and the adjustment period T of the opening adjustment step number of the electronic expansion valve according to the actual value of the suction superheat and the preset target value of the suction superheat, specifically includes:

Calculate the target value A of the opening adjustment step number according to the method shown in the following formula:

A=|Tsh-Tsh0|

Determine whether the opening adjustment step number target value A is greater than or equal to a preset step number threshold; if yes, set the adjustment period T to the preset first adjustment period; if not, set the adjustment period Is the preset second adjustment period;

Adjust the opening degree of the electronic expansion valve according to the comparison result of the actual value of the suction superheat degree and the preset target value of the suction superheat degree, as well as the opening degree adjustment step number target value A and the adjustment period T, Specifically:

If Tsh>Tsh0, the opening degree of the electronic expansion valve is successively increased according to the opening degree adjustment step number target value A and the adjustment period T within a certain period of time;

If Tsh<Tsh0, the opening degree of the electronic expansion valve is successively decreased according to the opening degree adjustment step number target value A and the adjustment period T within a certain period of time;

If Tsh=Tsh0, the opening degree of the electronic expansion valve is not adjusted;

Wherein, the Tsh and Tsh0 are the actual value of the suction superheat and the preset target value of the suction superheat, respectively, and the preset first adjustment period is smaller than the preset second adjustment period.
The refrigerant flow control system of an air conditioner according to claim 6, further comprising: the second flow adjustment module is configured to calculate the actual suction superheat of the compressor according to the method shown in the following formula value:

Tsh=Ts-min[Te, TC]

Wherein, the Tsh is the actual value of the suction superheat of the compressor, the Ts is the actual value of the suction temperature of the compressor, and the Te and TC are respectively along the evaporator in the outdoor unit The temperature of the bottom coil of the outdoor unit and the temperature of the middle coil of the outdoor unit in the bottom-up direction, "min" represents the minimum value function; and/or,

The temperature judgment module is configured to perform the following operations: detect the discharge pressure of the compressor in the air conditioner in real time, obtain the saturation temperature corresponding to the discharge pressure based on the corresponding relationship between the preset pressure and the saturation temperature, and obtain the saturation temperature corresponding to the discharge pressure according to the saturation Set the second temperature threshold for temperature; or obtain the second temperature threshold according to the method shown in the following formula:

Tthr=Tm+Tbc

Wherein, the Tthr is the preset second temperature threshold, the Tm is the indoor unit coil temperature in the air conditioner detected in real time, and the Tbc is the preset temperature compensation value.
The refrigerant flow control system for an air conditioner according to claim 6, further comprising: a first flow adjustment module configured to determine that the ambient temperature of the outdoor unit is less than or equal to a preset value when the temperature determination module determines After the first temperature threshold, and after the bottom temperature of the compressor is less than or equal to the preset second temperature threshold, continue to determine whether the operating time of the air conditioner in the heating mode reaches the preset time threshold; if so, decrease The opening degree of the electronic expansion valve on the refrigerant inlet side of the evaporator in the outdoor unit is used to reduce the flow rate of the refrigerant flowing into the evaporator, and then the ambient temperature judgment module is restarted.