WO2021218272A1

WO2021218272A1 - Method for controlling opening degree of expansion valve of air conditioning system

Info

Publication number: WO2021218272A1
Application number: PCT/CN2021/075276
Authority: WO
Inventors: 禚百田; 时斌; 程绍江; 张锐钢; 王军
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: 2020-04-26
Filing date: 2021-02-04
Publication date: 2021-11-04
Also published as: CN113551379A; CN113551379B

Abstract

A method for controlling the opening degree of an expansion valve of an air conditioning system, the air conditioning system comprising at least one outdoor unit, the outdoor unit comprising a compressor, a heat exchanger and an expansion valve corresponding to the heat exchanger. The method for controlling the opening degree of the expansion valve comprises: acquiring the superheat degree of a compressor (S1); if the superheat degree of the compressor is less than a preset superheat degree, adjusting the opening degree of the expansion valve according to the superheat degree of the compressor (S2); and if the superheat degree of the compressor is greater than or equal to the preset superheat degree, acquiring the superheat degree of the heat exchanger, and adjusting the opening degree of the expansion valve by combining the superheat degree of the heat exchanger with the superheat degree of the compressor or only according to the superheat degree of the heat exchanger (S3). On the basis of ensuring the safe operation of the compressor, the method may also take into account the heat exchange efficiency of the heat exchanger, and further also take into account the reliability and heat exchange efficiency of the air conditioning system.

Description

Method for controlling opening degree of expansion valve for air conditioning system

Technical field

The invention belongs to the technical field of air conditioning, and specifically provides a method for controlling the opening degree of an expansion valve for an air conditioning system.

Background technique

With the continuous improvement of people's living standards, the air-conditioning system has become an indispensable device in people's lives. In recent years, although the air-conditioning technology has developed to a very mature stage, there are still some areas for improvement in the existing air-conditioning system. Specifically, in order to effectively meet the heat exchange requirements of air conditioning systems, many existing air conditioning systems are equipped with multiple outdoor heat exchangers. However, due to various factors, the amount of refrigerant flowing through each outdoor heat exchanger is not the same As a result, the amount of refrigerant in some outdoor heat exchangers is too much, while the amount of refrigerant in some outdoor heat exchangers is too small; therefore, existing air conditioning systems are often only based on heat exchange requirements for each outdoor unit. The expansion valve is controlled, which leads to the problem that the compressor of the existing air-conditioning system is prone to liquid hammer.

Correspondingly, a new expansion valve opening control method used in an air conditioning system is needed in the art to solve the above-mentioned problems.

Summary of the invention

In order to solve the above-mentioned problems in the prior art, that is, to solve the problem that the existing air-conditioning system adjusts the expansion valve in a poor manner, the present invention provides an expansion valve opening control method for an air-conditioning system. The air-conditioning system includes At least one outdoor unit, the outdoor unit includes a compressor, a heat exchanger, and an expansion valve corresponding to the heat exchanger, and the expansion valve opening control method includes: obtaining the superheat of the compressor; If the superheating degree of the compressor is less than the preset superheating degree, the opening degree of the expansion valve is adjusted according to the superheating degree of the compressor; if the superheating degree of the compressor is greater than or equal to the preset superheating degree, then obtaining The degree of superheat of the heat exchanger is combined with the degree of superheat of the heat exchanger and the degree of superheat of the compressor, or the opening degree of the expansion valve is adjusted only according to the degree of superheat of the heat exchanger.

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, when the number of the outdoor unit is one, "if the superheat degree of the compressor is less than the preset degree of superheat, then according to the The step of "adjusting the degree of superheat of the compressor to the degree of opening of the expansion valve" specifically includes: if the degree of superheat of the compressor is less than a first preset degree of superheat, adjusting the expansion valve according to the degree of superheat of the compressor "If the degree of superheat of the compressor is greater than or equal to the preset degree of superheat, then the degree of superheat of the heat exchanger is obtained and combined with the degree of superheat of the heat exchanger and the compressor The step of “adjusting the degree of superheat or adjusting the opening degree of the expansion valve only according to the degree of superheat of the heat exchanger” specifically includes: if the degree of superheat of the compressor is greater than or equal to the first preset degree of superheat and less than or equal to The second preset superheat degree is to obtain the superheat degree of the heat exchanger, and adjust the opening degree of the expansion valve in combination with the superheat degree of the heat exchanger and the superheat degree of the compressor; if the compressor If the degree of superheat is greater than the second preset degree of superheat, the degree of superheat of the heat exchanger is obtained, and the opening degree of the expansion valve is adjusted only according to the degree of superheat of the heat exchanger.

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, the step of "adjusting the opening degree of the expansion valve according to the degree of superheat of the compressor" specifically includes: according to the degree of superheat of the compressor , The first degree of superheat is determined; the first degree of superheat is used as the target degree of superheat, and the opening degree of the expansion valve is adjusted.

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, the step of "adjusting the opening degree of the expansion valve according to the superheat degree of the heat exchanger and the degree of superheat of the compressor" specifically includes : Determine the second degree of superheat according to the degree of superheat of the heat exchanger; determine the third degree of superheat according to the degree of superheat of the compressor; calculate the sum of the product of the second degree of superheat and the first proportion The sum of the product of the third degree of superheat and the second proportion is recorded as the fourth degree of superheat; the fourth degree of superheat is used as the target degree of superheat, and the opening degree of the expansion valve is adjusted.

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, the step of "adjusting the opening degree of the expansion valve according to the degree of superheat of the heat exchanger" specifically includes: The degree of superheat is determined to determine the fifth degree of superheat; the fifth degree of superheat is used as the target degree of superheat, and the opening degree of the expansion valve is adjusted.

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, when the number of the outdoor units is multiple, the step of "obtaining the superheat degree of the compressor" specifically includes: obtaining all The superheat of the compressor; calculate the average of the superheats of all compressors, and record it as the first average; “If the superheat of the compressor is less than the preset superheat, then the compressor will be adjusted according to the superheat of the compressor. The step of "opening degree of expansion valve" specifically includes: if the first average value is less than the third preset superheat degree, adjusting the degree of opening of the expansion valve according to the superheat degree of the compressor; If the superheat degree of the engine is greater than or equal to the preset superheat degree, the superheat degree of the heat exchanger is obtained, and the step of adjusting the opening degree of the expansion valve according to the superheat degree of the heat exchanger specifically includes: If the first average value is greater than or equal to the third preset degree of superheat, the degree of superheat of the heat exchanger is obtained, and the opening degree of the expansion valve is adjusted according to the degree of superheat of the heat exchanger.

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, “if the first average value is less than the third preset degree of superheat, the expansion valve is adjusted according to the degree of superheat of the compressor. The step of “opening degree” specifically includes: if the first average value is less than the third preset superheat degree, adjusting the opening degree of the expansion valve accordingly according to the numerical range of the compressor superheat degree. .

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, “if the first average value is less than the third preset degree of superheat, then according to the value of the degree of superheat of the compressor The step of adjusting the opening degree of the expansion valve accordingly includes: if the first average value is greater than or equal to a fourth preset degree of superheat and less than the third preset degree of superheat, then according to the compressor The first correction value is determined in the numerical range of the superheat degree; the current target superheat degree is corrected according to the first correction value; the opening degree of the expansion valve is adjusted according to the corrected target superheat degree.

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, “if the first average value is less than the third preset degree of superheat, then according to the value of the degree of superheat of the compressor The step of adjusting the opening degree of the expansion valve accordingly” also includes: if the first average value is less than the fourth preset degree of superheat, then determining according to the numerical range in which the degree of superheat of the compressor is located A second correction value is obtained; the current target superheat degree is corrected according to the second correction value; the opening degree of the expansion valve is adjusted according to the corrected target superheat degree.

In the preferred technical solution of the method for controlling the opening degree of the expansion valve of the air-conditioning system, “if the first average value is greater than or equal to the third preset degree of superheat, the degree of superheat of the heat exchanger is acquired, And the step of adjusting the opening degree of the expansion valve according to the degree of superheat of the heat exchanger specifically includes: if the first average value is greater than or equal to the third preset degree of superheat, acquiring the heat exchanger The third correction value is determined according to the numerical range of the superheat degree of the heat exchanger; the current target superheat degree is corrected according to the third correction value; the current target superheat degree is adjusted according to the corrected target superheat degree Describe the opening of the expansion valve.

Those skilled in the art can understand that, in the technical solution of the present invention, the air conditioning system of the present invention includes at least one outdoor unit, and the outdoor unit includes a compressor, a heat exchanger, and the expansion valve. The opening degree control method includes: obtaining the superheat degree of the compressor, so as to ensure the safety of the compressor first, thereby effectively ensuring the normal use of the compressor; if the superheat degree of the compressor is less than a preset superheat degree, then The degree of superheat of the compressor adjusts the degree of opening of the expansion valve, thereby effectively avoiding the problem that the compressor is prone to damage due to liquid hammer, thereby effectively ensuring the reliability of the air conditioning system; if the degree of superheating of the compressor is greater than or Equal to the preset degree of superheat, then obtain the degree of superheat of the heat exchanger, and combine the degree of superheat of the heat exchanger with the degree of superheat of the compressor, or only adjust the superheat degree according to the degree of superheat of the heat exchanger. The opening degree of the expansion valve can effectively take into account the heat exchange efficiency of the heat exchanger on the basis of ensuring the safe operation of the compressor, and further take into account the reliability and heat exchange efficiency of the air conditioning system.

Description of the drawings

Figure 1 is a flow chart of the main steps of the expansion valve opening control method used in the air conditioning system of the present invention;

2 is a partial structural diagram of the outdoor unit of the air conditioning system according to the first preferred embodiment of the present invention;

3 is a flowchart of specific steps of the method for controlling the opening degree of an expansion valve according to the first preferred embodiment of the present invention;

4 is a schematic diagram of a partial structure of an outdoor unit of an air conditioning system according to a second preferred embodiment of the present invention;

Fig. 5 is a flow chart of specific steps of a method for controlling the opening degree of an expansion valve according to a second preferred embodiment of the present invention.

Detailed ways

The preferred embodiments of the present invention will be described below 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. For example, although the various steps of the method of the present invention are described in a specific order in this application, these orders are not limitative, and those skilled in the art can follow a different order without departing from the basic principles of the present invention. Perform the steps described.

It should be noted that, in the description of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be interpreted broadly. For example, they may be directly connected, may be indirectly connected through an intermediate medium, or may be The internal communication between the two elements. For those skilled in the art, the specific meaning of the above-mentioned terms in the present invention can be understood according to specific circumstances. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

The air conditioning system of the present invention includes an indoor unit and an outdoor unit. The outdoor unit includes at least one outdoor unit. The outdoor unit includes a compressor, a heat exchanger, and an expansion valve corresponding to the heat exchanger; The outdoor unit only includes one compressor, and the number of heat exchangers can be one or more, and the technicians can set it according to actual needs, and each heat exchanger passes through a gas pipe and a liquid pipe. Connected to the main pipe of the outdoor unit, the expansion valve corresponding to each heat exchanger is correspondingly arranged on the liquid pipe connected to the heat exchanger, so as to control the refrigerant flow in the heat exchanger. It should be noted that the present invention does not set any limitation on the specific type of the expansion valve, and technicians can set it by themselves according to actual use requirements. In addition, the air-conditioning system further includes a controller, which can obtain the detection data of various sensors, and can also control the operation of the air-conditioning system, for example, control the opening degree of the expansion valve, etc.; those skilled in the art It can be understood that the present invention does not impose any restrictions on the specific structure and model of the controller, and the controller can be the original controller of the air conditioning system, or it can be used to implement the expansion valve opening of the present invention. For the controller that is set separately according to the control method, technicians can set the specific structure and model of the controller by themselves according to actual use requirements.

First, refer to FIG. 1, which is a flowchart of the main steps of the expansion valve opening control method for the air conditioning system of the present invention. As shown in Figure 1, the expansion valve opening control method of the present invention mainly includes the following steps:

S1: Obtain the superheat of the compressor;

S2: If the superheat of the compressor is less than the preset superheat, adjust the opening of the expansion valve according to the superheat of the compressor;

S3: If the superheat of the compressor is greater than or equal to the preset superheat, obtain the superheat of the heat exchanger and combine the superheat of the heat exchanger with the superheat of the compressor or adjust the expansion only according to the superheat of the heat exchanger The opening of the valve.

In step S1, the superheat of the compressor is equal to the temperature of the gas pipe connected to the heat exchanger minus the saturation temperature corresponding to the low pressure pressure of the compressor, that is, according to each heat exchanger has its corresponding The degree of superheat of the compressor; it should be noted that the present invention does not impose any restriction on the manner in which the controller obtains the degree of superheat of the compressor, and technicians can set it by themselves according to actual usage requirements.

In step S2, if the controller determines that the degree of superheat of the compressor is less than the preset degree of superheat, it adjusts the opening degree of the expansion valve according to the degree of superheat of the compressor, so as to effectively avoid the compressor The problem of damage due to liquid hammering is prone to occur, thereby effectively ensuring the reliability of the air conditioning system. It should be noted that the technician needs to set the value of the preset superheat degree by himself according to actual use requirements. As long as the superheat degree of the compressor is less than the preset superheat degree, it can indicate that there is liquid in the compressor. Just hit the risk.

In step S3, if the controller determines that the degree of superheat of the compressor is greater than or equal to the preset degree of superheat, then the degree of superheat of the heat exchanger is obtained and combined with the degree of superheat and compression of the heat exchanger. The degree of superheat of the engine or the degree of opening of the expansion valve is adjusted only according to the degree of superheat of the heat exchanger, so that on the basis of ensuring the safe operation of the compressor, it can also effectively take into account the heat exchange of the heat exchanger. Efficiency, and at the same time give consideration to the reliability and heat exchange efficiency of the air-conditioning system. It should be noted that the superheat of the heat exchanger is equal to the temperature of the gas pipe connected to the heat exchanger minus the temperature of the liquid pipe connected to the heat exchanger; of course, the present invention does not obtain information from the controller There are any restrictions on the degree of superheat of the heat exchanger, and the technician can set it by himself according to actual use requirements.

The first preferred embodiment of the present invention will be described below in conjunction with FIG. 2 and FIG. 3.

First, refer to Figure 2, which is a partial structural diagram of the outdoor unit of the air conditioning system in the first preferred embodiment of the present invention; as shown in Figure 2, in the first preferred embodiment of the present invention, the outdoor unit of the air conditioning system The machine only includes one outdoor unit, the outdoor unit includes a compressor (not shown in the figure), a first heat exchanger 11, a first expansion valve 111 corresponding to the first heat exchanger 11, and a second heat exchanger 12 and a second expansion valve 121 corresponding to the second heat exchanger 12, the first heat exchanger 11 and the second heat exchanger 12 are both connected to the compressor; wherein, the first heat exchanger 11 passes through the first The gas pipe 112 and the first liquid pipe 113 are connected to the main pipe of the outdoor unit, and the first expansion valve 111 is arranged on the first liquid pipe 113 to control the flow of refrigerant in the first heat exchanger 11; The heat exchanger 12 is connected to the main pipe of the outdoor unit through the second gas pipe 122 and the second liquid pipe 123, and the second expansion valve 121 is arranged on the second liquid pipe 123 to control the flow of refrigerant in the second heat exchanger 12 . In addition, a first gas pipe temperature sensor is provided on the first gas pipe 112 to obtain the temperature of the first gas pipe 112, and a first liquid pipe temperature sensor is installed on the first liquid pipe 113 to obtain the temperature of the first liquid pipe 113. The second gas pipe 122 is provided with a second gas pipe temperature sensor to obtain the temperature of the second gas pipe 122, and the second liquid pipe 123 is provided with a second liquid pipe temperature sensor to obtain the temperature of the second liquid pipe 123. Of course, this is not the case. It is not restrictive, and technicians can also obtain these temperatures in other ways.

Next, refer to FIG. 3, which is a flowchart of specific steps of the method for controlling the opening of the expansion valve according to the first preferred embodiment of the present invention. As shown in Fig. 3, based on the air conditioning system described in the above embodiment, the expansion valve opening control method of the present invention specifically includes the following steps:

S101: Obtain the superheat of the compressor;

S102: If the superheating degree of the compressor is less than the first preset superheating degree, adjust the opening degree of the expansion valve according to the superheating degree of the compressor;

S103: If the superheat of the compressor is greater than or equal to the first preset superheat and less than or equal to the second preset superheat, the superheat of the heat exchanger is obtained, and the superheat of the heat exchanger is combined with the superheat of the compressor. Heat adjusts the opening of the expansion valve;

S104: If the superheat degree of the compressor is greater than the second preset superheat degree, obtain the superheat degree of the heat exchanger, and adjust the opening degree of the expansion valve according to the superheat degree of the heat exchanger.

In this preferred embodiment, the outdoor unit includes a first heat exchanger 11 and a second heat exchanger 12, and the controller can perform the first heat exchanger 11 and the second heat exchanger 12 separately according to the above steps. Control accordingly. It should be noted that the first heat exchanger 11 and the second heat exchanger 12 in this preferred embodiment are different types of heat exchangers, so their setting data are different. Of course, the outdoor unit may also include only one heat exchanger, that is, a part of it can be directly used.

The specific control method for the first heat exchanger 11 is as follows:

In step S101, the superheat degree of the compressor CompSH1=Tg1-Pstemp; where Tg1 is the temperature of the first gas pipe 112 detected by the first gas pipe temperature sensor, and Pstemp is the low pressure pressure of the compressor corresponding to In addition, it should be noted that the present invention does not impose any restrictions on the specific method for the controller to obtain the compressor superheat CompSH1, and the technician can set it according to actual use requirements.

In step S102, if the controller determines that the degree of superheat CompSH1 of the compressor is less than the first preset degree of superheat, the controller adjusts the first expansion valve 111 according to the degree of superheat CompSH1 of the compressor. The opening. Specifically, the controller can determine the first degree of superheat A1 according to the degree of superheat CompSH1 of the compressor, so that the controller can adjust the opening degree of the first expansion valve 111 with the first degree of superheat A1 as the target degree of superheat. That is, the adjustment value of the opening degree of the first expansion valve 111 is determined based on the difference between the current superheat degree and the target superheat degree, so as to effectively prevent the compressor from being damaged by the liquid hammer phenomenon, thereby effectively ensuring the reliability of the compressor. It should be noted that the present invention does not impose any restriction on the specific manner of determining the first superheat degree A1 according to the compressor superheat degree CompSH1; preferably, the compressor superheat degree CompSH1 and the first superheat degree A1 are one to one. Correspondence, that is, the only first degree of superheat A1 can be determined according to the degree of superheat CompSH1 of the compressor. In addition, the present invention does not impose any limitation on the specific values of the first preset superheat degree and the first superheat degree A1, and technicians can set it according to actual use requirements; preferably, the first preset superheat degree and The first degree of superheat A1 is all 3°C.

In step S103, if the controller determines that the compressor superheat CompSH1 is greater than or equal to the first preset superheat and less than or equal to the second preset superheat, the controller obtains The degree of superheat of the first heat exchanger 11, the degree of superheat of the first heat exchanger 11 ExSH1=Tg1-Te1; where Tg1 is the temperature of the first air pipe 112 detected by the first air pipe temperature sensor, and Te1 is the passing The first liquid pipe temperature sensor detects the temperature of the first liquid pipe 113, and adjusts the opening degree of the first expansion valve 111 according to the superheat degree ExSH1 of the first heat exchanger 11 and the superheat degree CompSH1 of the compressor, In order to take into account the reliability of the compressor and the heat exchange efficiency of the air conditioning system at the same time. It should be noted that the technician can set the specific value of the second preset superheat degree by himself according to actual use requirements. Preferably, the second preset superheat degree is 5°C. Specifically, the controller can determine the second degree of superheat B1 according to the degree of superheat ExSH1 of the first heat exchanger 11, and then determine the third degree of superheat C1 according to the degree of superheat CompSH1 of the compressor; it should be noted that, The present invention does not impose any limitation on the above-mentioned specific determination method. The technician can set it according to actual use requirements. Preferably, the second superheat degree B1 can be based on one of the superheat degree ExSH1 of the first heat exchanger 11 and the second superheat degree B1. The determination can be made in a corresponding manner, or the preferred value 4° C. can also be directly adopted; the third degree of superheat C1 is preferably one half of the sum of the first predetermined degree of superheat and the second predetermined degree of superheat. Next, the controller calculates the sum of the product of the second degree of superheat B1 and the first proportion and the sum of the product of the third degree of superheat C1 and the second proportion, which is recorded as the fourth degree of superheat D1, so that the The controller can use the fourth degree of superheat D1 as the target degree of superheat to adjust the opening degree of the first expansion valve 111; it should be noted that although the preferred embodiment is directly determined according to the second degree of superheat B1 and the third degree of superheat C1 The fourth degree of superheat D1 is obtained, and then the adjustment value of the opening degree of the first expansion valve 111 is determined according to the fourth degree of superheat D1; however, those skilled in the art can obviously also determine the corresponding degree of opening adjustment according to the second degree of superheat B1. The corresponding opening adjustment value is determined according to the third degree of superheat C1, and finally the final opening of the first expansion valve 111 is determined according to the determined two opening adjustment values, the first proportion and the second proportion. Degree adjustment value. In addition, it should be noted that the technical personnel can set the specific values of the first proportion and the second proportion according to actual use requirements. As a preferred embodiment, the first proportion and the second proportion The sum of the second proportion is 1, and the first proportion is preferably set to 60%, and the second proportion is preferably set to 40%.

In step S104, if the controller determines that the degree of superheat CompSH1 of the compressor is greater than the second preset degree of superheat, the controller adjusts the first expansion according to the degree of superheat ExSH1 of the first heat exchanger 11. The opening of the valve 111. Specifically, the controller can determine the fifth degree of superheat E1 according to the degree of superheat ExSH1 of the first heat exchanger 11, so that the controller can adjust the first expansion valve 111 with the fifth degree of superheat E1 as the target degree of superheat. The opening degree; wherein the fifth degree of superheat E1 is less than the second degree of superheat B1, so as to effectively improve the heat exchange effect of the air conditioning system. It should be noted that the present invention does not impose any limitation on the specific method of determining the fifth degree of superheat E1 based on the degree of superheat ExSH1 of the first heat exchanger 11; preferably, the degree of superheat ExSH1 of the first heat exchanger 11 is different from the fifth degree of superheat. The degree of heat E1 has a one-to-one correspondence, that is, the only fifth degree of superheat E1 can be determined according to the degree of superheat ExSH1 of the first heat exchanger 11; alternatively, the fifth degree of superheat E1 is directly set to a preferred value of 2°C.

The specific control method for the second heat exchanger 12 is as follows:

In step S101, the superheat degree of the compressor CompSH2=Tg2-Pstemp; where Tg2 is the temperature of the second gas pipe 122 detected by the second gas pipe temperature sensor, and Pstemp is the low pressure pressure of the compressor corresponding to In addition, it should be noted that the present invention does not impose any restriction on the specific method for the controller to obtain the compressor superheat CompSH2, and the technician can set it according to actual use requirements.

In step S102, if the controller determines that the degree of superheat CompSH2 of the compressor is less than the first preset degree of superheat, the controller adjusts the second expansion valve 121 according to the degree of superheat CompSH2 of the compressor. The opening. Specifically, the controller can determine the first degree of superheat A2 according to the degree of superheat CompSH2 of the compressor, so that the controller can adjust the opening degree of the second expansion valve 121 with the first degree of superheat A2 as the target degree of superheat That is, the adjustment value of the opening degree of the second expansion valve 121 is determined based on the difference between the current degree of superheat and the target degree of superheat, so as to effectively prevent the compressor from being damaged by the liquid hammer phenomenon, thereby effectively ensuring the reliability of the compressor. It should be noted that the present invention does not impose any limitation on the specific manner of determining the first superheat degree A2 according to the compressor superheat degree CompSH2; preferably, the compressor superheat degree CompSH2 and the first superheat degree A2 are one to one. Correspondence, that is, the only first degree of superheat A2 can be determined according to the degree of superheat CompSH2 of the compressor. In addition, the present invention does not impose any limitation on the specific values of the first preset superheat degree and the first superheat degree A2, and technicians can set it according to actual use requirements; preferably, the first preset superheat degree and The first degree of superheat A1 is 4°C.

In step S103, if the controller determines that the compressor superheat CompSH2 is greater than or equal to the first preset superheat and less than or equal to the second preset superheat, the controller obtains The degree of superheat of the second heat exchanger 12, the degree of superheat of the second heat exchanger 12 ExSH2=Tg2-Te2; wherein, Tg2 is the temperature of the second air pipe 122 detected by the second air pipe temperature sensor, and Te2 is the passing The second liquid pipe temperature sensor detects the temperature of the second liquid pipe 123, and adjusts the opening degree of the second expansion valve 121 according to the degree of superheat ExSH2 of the second heat exchanger 12 and the degree of superheat CompSH2 of the compressor, In order to take into account the reliability of the compressor and the heat exchange efficiency of the air conditioning system at the same time. It should be noted that the technician can set the specific value of the second preset superheat degree by himself according to actual use requirements. Preferably, the second preset superheat degree is 6°C. Specifically, the controller can determine the second degree of superheat B1 according to the degree of superheat ExSH2 of the second heat exchanger 12, and then determine the third degree of superheat C1 according to the degree of superheat CompSH2 of the compressor; it should be noted that, The present invention does not impose any limitation on the above-mentioned specific determination method. The technician can set it according to actual use requirements. Preferably, the second superheat degree B1 can be based on one of the superheat degree ExSH2 of the second heat exchanger 12 and the second superheat degree B1. The determination is made in a corresponding manner, or the preferred value of 5° C. can also be directly adopted; the third degree of superheat C1 is preferably one half of the sum of the first preset degree of superheat and the second preset degree of superheat. Next, the controller calculates the sum of the product of the second degree of superheat B1 and the first proportion and the sum of the product of the third degree of superheat C1 and the second proportion, which is recorded as the fourth degree of superheat D1, so that the The controller can use the fourth degree of superheat D1 as the target degree of superheat to adjust the opening degree of the second expansion valve 121; it should be noted that although the preferred embodiment is directly determined according to the second degree of superheat B1 and the third degree of superheat C1 The fourth degree of superheat D1 is obtained, and then the adjustment value of the opening degree of the second expansion valve 121 is determined according to the fourth degree of superheat D1; however, those skilled in the art can obviously also determine the corresponding opening degree adjustment first according to the second degree of superheat B1 The corresponding opening adjustment value is determined according to the third degree of superheat C1, and finally the final opening of the second expansion valve 121 is determined according to the two determined opening adjustment values, the first proportion and the second proportion. Degree adjustment value. In addition, it should be noted that the technical personnel can set the specific values of the first proportion and the second proportion according to actual use requirements. As a preferred embodiment, the first proportion and the second proportion The sum of the second proportion is 1, and both the first proportion and the second proportion are preferably set to 50%.

In step S104, if the controller determines that the degree of superheat CompSH2 of the compressor is greater than the second preset degree of superheat, the controller adjusts the second expansion according to the degree of superheat ExSH2 of the second heat exchanger 12 The degree of opening of the valve 121. Specifically, the controller can determine the fifth degree of superheat E1 according to the degree of superheat ExSH2 of the second heat exchanger 12, so that the controller can adjust the second expansion valve 121 with the fifth degree of superheat E1 as the target degree of superheat. The opening degree; wherein the fifth degree of superheat E1 is less than the second degree of superheat B1, so as to effectively improve the heat exchange effect of the air conditioning system. It should be noted that the present invention does not impose any limitation on the specific manner of determining the fifth degree of superheat E1 according to the degree of superheat ExSH2 of the second heat exchanger 12; preferably, the degree of superheat ExSH2 of the second heat exchanger 12 is different from the fifth degree of superheat The degree of heat E1 has a one-to-one correspondence, that is, the only fifth degree of superheat E1 can be determined according to the degree of superheat ExSH2 of the second heat exchanger 12; alternatively, the fifth degree of superheat E1 is directly set to a preferred value of 3°C.

Based on the first preferred embodiment, it should also be noted that technicians can set the first preset superheat degree, the second preset superheat degree, and the first superheat degree by themselves according to the specific type of the heat exchanger. , The specific values of the second degree of superheat, the third degree of superheat, the fifth degree of superheat, the first proportion and the second proportion, so as to effectively improve the control effect.

The second preferred embodiment of the present invention will be described below in conjunction with FIG. 4 and FIG. 5:

First, refer to Figure 4, which is a partial structural diagram of the outdoor unit of the air conditioning system in the second preferred embodiment of the present invention; as shown in Figure 4, in the second preferred embodiment of the present invention, the outdoor unit of the air conditioning system The machine includes a plurality of outdoor units. Since the structure of the outdoor unit is the same as the outdoor unit described in the first preferred embodiment, it will not be repeated here. Please refer directly to the structure in the first preferred embodiment. It should be noted that technicians can set the specific number of outdoor units and the number of heat exchangers set in each outdoor unit according to actual use needs. As long as the number of outdoor units is greater than 1, the number of outdoor units is set in each outdoor unit. The number of heat exchangers can be one or more.

Next, refer to FIG. 5, which is a flow chart of specific steps of the method for controlling the opening degree of the expansion valve according to the second preferred embodiment of the present invention. As shown in FIG. 5, based on the air conditioning system described in the above embodiment, the expansion valve opening control method of the present invention specifically includes the following steps:

S201: Obtain the superheat of all compressors;

S202: Calculate the average value of the superheat of all compressors and record it as the first average value;

S203: If the first average value is less than the fourth preset degree of superheat, the second correction value is determined according to the numerical range of the compressor superheat degree, and the current target superheat degree is corrected according to the second correction value, and then according to The revised target superheat degree, adjust the opening degree of the expansion valve;

S204: If the first average value is greater than or equal to the fourth preset degree of superheat and less than the third preset degree of superheat, the first correction value is determined according to the numerical range of the compressor superheat degree, and according to the first correction value Correct the current target superheat, and then adjust the opening of the expansion valve according to the corrected target superheat;

S205: If the first average value is greater than or equal to the third preset superheat degree, obtain the superheat degree of the heat exchanger, determine the third correction value according to the numerical range of the superheat degree of the heat exchanger, and make the third correction value according to the third correction value. The value corrects the current target superheat, and then adjusts the opening degree of the expansion valve according to the corrected target superheat.

Specifically, in step S201, the controller can obtain the superheats of all compressors, and the calculation of the superheats of the compressors is the same as that in the first preferred embodiment, and will not be repeated here. Next, in step S202, the controller can calculate the average value of the superheat of all compressors, which is recorded as the first average value; the specific calculation method is: the first average value CompSH_AVG=[(CompSH1 of outdoor unit 1 + outdoor CompSH2 of unit 1)+(CompSH1 of outdoor unit 2+CompSH2 of outdoor unit 2)+...+(CompSH1 of outdoor unit n+CompSH2 of outdoor unit n)]/2n; where n is the total number of outdoor units.

Further, in step S203, if the controller determines that the first average value is less than the fourth preset degree of superheat, the adjustment value of the expansion valve corresponding to each heat exchanger is all First, determine the second correction value fix2 according to the value range of the compressor superheat CompSH corresponding to the heat exchanger, and correct the current target superheat according to the second correction value fix2, and then according to the corrected target superheat , Adjust the opening degree of the expansion valve corresponding to the heat exchanger, so as to effectively protect the safety of the compressor, thereby effectively ensuring the reliability of the air conditioning system. It should be noted that the technician can set the value of the fourth preset superheat degree by himself according to actual use requirements; preferably, the fourth preset superheat degree is 1°C. As a preferred embodiment, the specific method for determining the second correction value fix2 according to the numerical range of the compressor superheat CompSH is in the following table:

压缩机的过热度CompSH所处的数值范围The value range of the compressor superheat CompSH	修正值fix2(单位：℃)Correction value fix2 (unit: ℃)
CompSH＜(CompSH_AVG－阈值2)CompSH＜(CompSH_AVG－Threshold 2)	33
(CompSH_AVG－阈值2)≤CompSH＜(CompSH_AVG－阈值1)(CompSH_AVG－Threshold 2)≤CompSH＜(CompSH_AVG－Threshold 1)	2.52.5
(CompSH_AVG－阈值1)≤CompSH≤(CompSH_AVG+阈值1)(CompSH_AVG－Threshold 1)≤CompSH≤(CompSH_AVG+Threshold 1)	11
CompSH＞(CompSH_AVG+阈值1)CompSH＞(CompSH_AVG+threshold 1)	00

Wherein, CompSH_AVG is the first average value, and the specific values of threshold value 1 and threshold value 2 can be set according to actual use requirements; preferably, threshold value 2 is greater than threshold value 1, and threshold value 1 is set to 1°C, and threshold value 2 is set to Set at 3°C.

Further, in step S204, if the controller determines that the first average value is greater than or equal to the fourth preset degree of superheat and less than the third preset degree of superheat, then for each heat exchanger corresponding to Regarding the adjustment value of the expansion valve, the first correction value fix1 is determined according to the value range of the compressor superheat CompSH corresponding to the heat exchanger, and the current target superheat degree is determined according to the first correction value fix1. Make the correction, and then adjust the opening degree of the expansion valve corresponding to the heat exchanger according to the corrected target superheat. It should be noted that the technician can set the specific value of the third preset superheat degree by himself according to actual use requirements. Preferably, the third preset superheat degree is 3°C. As a preferred embodiment, the specific method for determining the first correction value fix1 according to the numerical range of the compressor superheat CompSH is in the following table:

压缩机的过热度CompSH所处的数值范围The value range of the compressor superheat CompSH	修正值fix1(单位：℃)Correction value fix1 (unit: ℃)
CompSH＜(CompSH_AVG－阈值2)CompSH＜(CompSH_AVG－Threshold 2)	1.51.5
(CompSH_AVG－阈值2)≤CompSH＜(CompSH_AVG－阈值1)(CompSH_AVG－Threshold 2)≤CompSH＜(CompSH_AVG－Threshold 1)	11
(CompSH_AVG－阈值1)≤CompSH≤(CompSH_AVG+阈值1)(CompSH_AVG－Threshold 1)≤CompSH≤(CompSH_AVG+Threshold 1)	0.50.5
CompSH＞(CompSH_AVG+阈值1)CompSH＞(CompSH_AVG+threshold 1)	00

Further, in step S204, if the controller determines that the first average value is greater than or equal to the third preset degree of superheat, the controller obtains the degree of superheat of the heat exchanger, and then The degree of superheat of the heat exchanger adjusts the degree of opening of the expansion valve. Specifically, in the case that the first average value is greater than or equal to the third preset degree of superheat, the controller obtains the degree of superheat of all heat exchangers, and the method of calculating the degree of superheat of the heat exchanger is the same as that of the first The calculation method in the preferred embodiment will not be repeated here. Next, calculate the average value of the superheat of all heat exchangers and record it as the second average value; the specific calculation method is: the second average value ExSH_AVG=[(ExSH1 of outdoor unit 1+ExSH2 of outdoor unit 1)+(outdoor unit 2 ExSH1+ExSH2 of outdoor unit 2)+...+(ExSH1 of outdoor unit n+ExSH2 of outdoor unit n)]/2n; where n is the total number of outdoor units. The adjustment value of the expansion valve corresponding to each heat exchanger is specifically determined according to the value range of the superheat ExSH of the heat exchanger, that is, the third correction value is determined according to the superheat ExSH of the heat exchanger fix3, and correct the current target superheat degree according to the third correction value fix3, so that the controller can adjust the opening degree of the corresponding expansion valve according to the revised target superheat degree, so as to effectively ensure the heat exchange of the air conditioning system efficient. As a preferred embodiment, the specific method for determining the third correction value fix3 according to the numerical range of the superheat ExSH of the heat exchanger is as follows:

换热器的过热度ExSH所处的数值范围The value range of the superheat ExSH of the heat exchanger	修正值fix1(单位：℃)Correction value fix1 (unit: ℃)
ExSH＜(ExSH_AVG－阈值4)ExSH＜(ExSH_AVG－Threshold 4)	1.51.5
(ExSH_AVG－阈值4)≤ExSH＜(ExSH_AVG－阈值3)(ExSH_AVG－Threshold 4)≤ExSH＜(ExSH_AVG－Threshold 3)	0.50.5
(ExSH_AVG－阈值3)≤ExSH≤(ExSH_AVG+阈值3)(ExSH_AVG－Threshold 3)≤ExSH≤(ExSH_AVG+Threshold 3)	00
(ExSH_AVG+阈值3)＜ExSH≤(ExSH_AVG+阈值4)(ExSH_AVG+threshold 3)＜ExSH≤(ExSH_AVG+threshold 4)	-1.5-1.5
ExSH＞(ExSH_AVG+阈值4)ExSH＞(ExSH_AVG+threshold 4)	-2.5-2.5

Wherein, ExSH_AVG is the second average value, the specific values of threshold 3 and threshold 4 can be set according to actual use requirements; preferably, threshold 4 is greater than threshold 3, and threshold 3 is set to 2°C, and threshold 4 is set It is 4°C.

Based on the second preferred embodiment, it should also be noted that the present invention does not make any modification to the specific determination method of the target superheat. As a preferred method, the technician can first use the method described in the first preferred embodiment The opening degree of each expansion valve is determined for each outdoor unit, and then the opening degree of each expansion valve is corrected according to the method in the second preferred embodiment.

Finally, it should be noted that the above-mentioned examples are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Those skilled in the art can appropriately add or delete a part of the steps, or exchange the order between different steps, as needed when actually using the present invention. This change does not go beyond the basic principle of the present invention, and belongs to the protection scope of the present invention.

So far, the technical solutions of the present invention have been described with reference to the accompanying drawings. However, those skilled in the art will readily 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

An expansion valve opening control method for an air conditioning system, wherein the air conditioning system includes at least one outdoor unit, and the outdoor unit includes a compressor, a heat exchanger, and an expansion valve corresponding to the heat exchanger. The method for controlling the opening degree of the expansion valve includes:

Obtaining the superheat of the compressor;

If the degree of superheat of the compressor is less than the preset degree of superheat, adjusting the opening degree of the expansion valve according to the degree of superheat of the compressor;

If the superheat of the compressor is greater than or equal to the preset superheat, the superheat of the heat exchanger is obtained, and the superheat of the heat exchanger is combined with the superheat of the compressor or only according to The degree of superheat of the heat exchanger adjusts the degree of opening of the expansion valve.
The expansion valve opening degree control method according to claim 1, wherein when the number of the outdoor unit is one, “if the superheat degree of the compressor is less than a preset degree of superheat, then according to the The step of adjusting the degree of superheat of the compressor to the degree of opening of the expansion valve specifically includes:

If the degree of superheat of the compressor is less than the first preset degree of superheat, adjusting the opening degree of the expansion valve according to the degree of superheat of the compressor;

"If the degree of superheat of the compressor is greater than or equal to the preset degree of superheat, then the degree of superheat of the heat exchanger is obtained, combined with the degree of superheat of the heat exchanger and the degree of superheat of the compressor, or only The step of adjusting the opening degree of the expansion valve according to the degree of superheat of the heat exchanger specifically includes:

If the degree of superheat of the compressor is greater than or equal to the first preset degree of superheat and less than or equal to the second preset degree of superheat, the degree of superheat of the heat exchanger is obtained and combined with the degree of superheat of the heat exchanger. The degree of heat and the degree of superheat of the compressor adjust the opening degree of the expansion valve;

If the degree of superheat of the compressor is greater than the second preset degree of superheat, the degree of superheat of the heat exchanger is acquired, and the opening degree of the expansion valve is adjusted only according to the degree of superheat of the heat exchanger.
The method for controlling the opening degree of an expansion valve according to claim 2, wherein the step of "adjusting the opening degree of the expansion valve according to the degree of superheat of the compressor" specifically comprises:

Determine the first degree of superheat according to the degree of superheat of the compressor;

Regarding the first degree of superheat as the target degree of superheat, the opening degree of the expansion valve is adjusted.
The method for controlling the opening degree of an expansion valve according to claim 2, wherein the step of "adjusting the opening degree of the expansion valve according to the superheat degree of the heat exchanger and the superheat degree of the compressor" specifically comprises:

Determine the second degree of superheat according to the degree of superheat of the heat exchanger;

Determine the third degree of superheat according to the degree of superheat of the compressor;

Calculate the sum of the product of the second degree of superheat and the first proportion and the product of the third degree of superheat and the second proportion, and record it as the fourth degree of superheat;

Regarding the fourth degree of superheat as the target degree of superheat, the opening degree of the expansion valve is adjusted.
The method for controlling the opening degree of an expansion valve according to claim 2, wherein the step of "adjusting the opening degree of the expansion valve according to the degree of superheat of the heat exchanger" specifically comprises:

Determine the fifth degree of superheat according to the degree of superheat of the heat exchanger;

Regarding the fifth degree of superheat as a target degree of superheat, the opening degree of the expansion valve is adjusted.
The method for controlling the opening degree of an expansion valve according to claim 1, wherein when the number of outdoor units is multiple, the step of "obtaining the degree of superheat of the compressor" specifically includes:

Obtain the superheat of all compressors;

Calculate the average value of the superheat of all compressors and record it as the first average value;

"If the degree of superheat of the compressor is less than the preset degree of superheat, adjusting the opening degree of the expansion valve according to the degree of superheat of the compressor" specifically includes:

If the first average value is less than the third preset degree of superheat, adjusting the opening degree of the expansion valve according to the degree of superheat of the compressor;

"If the degree of superheat of the compressor is greater than or equal to the preset degree of superheat, then obtain the degree of superheat of the heat exchanger, and adjust the opening degree of the expansion valve according to the degree of superheat of the heat exchanger" The specific steps include:

If the first average value is greater than or equal to the third preset degree of superheat, the degree of superheat of the heat exchanger is acquired, and the degree of opening of the expansion valve is adjusted according to the degree of superheat of the heat exchanger.
The method for controlling the opening degree of an expansion valve according to claim 6, wherein “if the first average value is less than a third preset degree of superheat, the opening of the expansion valve is adjusted according to the degree of superheat of the compressor. The steps of "degree" specifically include:

If the first average value is less than the third preset degree of superheat, the opening degree of the expansion valve is adjusted accordingly according to the numerical range of the degree of superheat of the compressor.
7. The expansion valve opening control method according to claim 7, characterized in that, "if the first average value is less than the third preset degree of superheat, then according to the numerical range of the degree of superheat of the compressor The step of adjusting the opening degree of the expansion valve accordingly includes:

If the first average value is greater than or equal to the fourth preset degree of superheat and less than the third preset degree of superheat, a first correction value is determined according to the numerical range of the degree of superheat of the compressor;

Correcting the current target superheat degree according to the first correction value;

According to the corrected target superheat degree, the opening degree of the expansion valve is adjusted.
The expansion valve opening degree control method according to claim 8, wherein “if the first average value is less than the third preset degree of superheat, then according to the numerical range of the degree of superheat of the compressor The step of adjusting the opening degree of the expansion valve correspondingly also includes:

If the first average value is less than the fourth preset degree of superheat, a second correction value is determined according to the numerical range of the degree of superheat of the compressor;

Correcting the current target superheat degree according to the second correction value;

According to the corrected target superheat degree, the opening degree of the expansion valve is adjusted.
The method for controlling the opening degree of an expansion valve according to claim 6, wherein “if the first average value is greater than or equal to the third preset degree of superheat, the degree of superheat of the heat exchanger is acquired, and The step of adjusting the opening degree of the expansion valve according to the degree of superheat of the heat exchanger specifically includes:

If the first average value is greater than or equal to the third preset degree of superheat, acquiring the degree of superheat of the heat exchanger;

Determine the third correction value according to the numerical range of the superheat of the heat exchanger;

Correcting the current target superheat degree according to the third correction value;

According to the corrected target superheat degree, the opening degree of the expansion valve is adjusted.