Method and device for controlling refrigerant amount of multi-split air conditioning system

Abstract

According to the refrigerant amount control method and device for the multi-split system, the multi-split system comprises an outdoor unit and a plurality of indoor units, the indoor units comprise floor heating units and air conditioners, only one indoor unit is in a running state, and the method comprises the steps that the exhaust pressure and the exhaust temperature of a compressor of the outdoor unit are obtained; the refrigerant insufficiency rate of the multi-split air conditioning system is obtained; and based on the exhaust pressure, the exhaust temperature and the refrigerant insufficiency rate, the opening degrees of electronic expansion valves of the multiple indoor units which are not operated are controlled, so that the amount of refrigerants circulating in the multi-split system is adjusted.

Description

Technical Field

[0001] The present application relates to the field of multi-split systems, and in particular to a method and device for controlling the amount of refrigerant in a multi-split system operating with a single indoor unit. Background Art

[0002] At present, in multi-split systems connected to floor heating, floor heating often needs to work independently. The existing multi-split systems with floor heating modules mainly control the opening of the electronic expansion valves of other indoor units (also called rest rooms) in the shutdown state through the compressor exhaust temperature and the refrigerant content in the system, so that the refrigerant amount in the system reaches the range when the floor heating is running alone.

[0003] However, when the exhaust pressure is high, if the exhaust temperature is also high, the PMV opening of the rest chamber will be automatically increased, allowing the refrigerant stored in the rest chamber to participate in the system circulation, causing the originally excessive exhaust pressure to continue to rise, thereby causing high-pressure frequency limiting and reduced capacity. In addition, in this control, if the exhaust temperature threshold is set low, the PMV opening of the rest chamber is easy to open wide, which will also cause the risk of continued increase in exhaust pressure.

[0004] At the same time, during the actual installation process, due to the diversity and randomness of the on-site systems, as well as the deviations in the refrigerant filling amounts, relying solely on the exhaust temperature and refrigerant insufficiency rate to control the system's refrigerant circulation volume will increase the uncertainty of the floor heating capacity, and the risk of the floor heating module reducing user experience due to insufficient capacity will also increase significantly. Summary of the invention

[0005] The multi-split system is a system where one outdoor unit is connected to control multiple indoor units, which may include air conditioners and floor heating. When only a single indoor unit is working, the existing method for controlling the amount of refrigerant may cause the exhaust pressure in the multi-split system to be too high and reduce the risk of working performance. This application proposes a method for controlling the amount of refrigerant to overcome this problem. The method includes:

[0006] Obtaining the exhaust pressure and exhaust temperature of the compressor of the external unit;

[0007] Obtaining a refrigerant shortage rate of the multi-split system;

[0008] The opening degrees of the electronic expansion valves of the plurality of indoor units that are not in operation are controlled based on the exhaust pressure, the exhaust temperature, and the refrigerant deficiency rate to adjust the amount of refrigerant circulating in the multi-split system.

[0009] Optionally, controlling the opening of the electronic expansion valves of the plurality of indoor units that are not in operation based on the exhaust pressure, the exhaust temperature and the refrigerant deficiency rate includes:

[0010] When the refrigerant shortage rate is greater than a first refrigerant threshold and / or the exhaust temperature is greater than a first temperature threshold, increasing the opening of the electronic expansion valves of the plurality of indoor units that are not in operation;

[0011] When the exhaust temperature is less than or equal to a third temperature threshold, and the refrigerant shortage rate is less than or equal to a second refrigerant threshold, reducing the opening of the electronic expansion valves of the plurality of indoor units that are not in operation;

[0012] When the exhaust temperature is greater than the second temperature threshold and less than or equal to the first temperature threshold, and the exhaust pressure is greater than the pressure threshold, the openings of the electronic expansion valves of the multiple indoor units remain unchanged;

[0013] When the exhaust temperature is greater than the second temperature threshold and less than or equal to the first temperature threshold, and the exhaust pressure is less than or equal to the pressure threshold, increasing the opening of the electronic expansion valves of the multiple indoor units that are not in operation;

[0014] When the exhaust temperature is greater than the third temperature threshold and less than or equal to the second temperature threshold and / or the exhaust temperature is less than or equal to the third temperature threshold, and the refrigerant deficiency rate is greater than the second refrigerant threshold, the opening of the electronic expansion valves of the multiple indoor units remains unchanged.

[0015] Optionally, the first refrigerant threshold is 30% and / or the second refrigerant threshold is 15%.

[0016] Optionally, the first temperature threshold is 95°C and / or the second temperature threshold is 90°C and / or the third temperature threshold is 85°C.

[0017] Optionally, the pressure threshold is 32kgf / cm2.

[0018] Optionally, when the opening degrees of the electronic expansion valves of the plurality of indoor units that are not in operation are increased or decreased, the rate of change of the opening degrees is an increase or decrease of 15 pls every five minutes.

[0019] Optionally, the upper limit of the opening is 180 pls and the lower limit is 60 pls.

[0020] Optionally, the refrigerant shortage rate is obtained by the following formula:

[0021] Ph(n)=1.0-P1%

[0022] Wherein, Rh(n) is the refrigerant shortage rate, P1% is the pressure ratio, and the pressure ratio is obtained by the following formula:

[0023] P1%=(PL-Ps) / (Pd-Ps)×m+n

[0024] Wherein, PL is the saturated pressure in the liquid pipe obtained by the liquid pipe temperature of the multi-split system, Ps is the suction pressure of the compressor, Pd is the exhaust pressure, and m and n are compensation constants. Preferably, m is 1.23 and n is 0.24.

[0025] The present application also proposes a device for controlling the amount of refrigerant in a multi-split system for single floor heating operation, the multi-split system comprising an outdoor unit and a plurality of indoor units, the plurality of indoor units comprising floor heating and air conditioning, wherein only a single floor heating is in operation, comprising:

[0026] A parameter acquisition unit, used to acquire the exhaust pressure and exhaust temperature of the compressor of the external unit;

[0027] A parameter calculation unit, used to obtain a refrigerant shortage rate of the multi-split system;

[0028] A control unit is used to control the opening of the electronic expansion valves of the multiple indoor units that are not in operation based on the exhaust pressure, the exhaust temperature and the refrigerant deficiency rate to adjust the amount of refrigerant circulating in the multi-split system.

[0029] By using the above-mentioned method and device for controlling the amount of refrigerant in a multi-split system operating with a single indoor unit, comprehensive consideration is introduced to the compressor exhaust temperature, exhaust pressure and system refrigerant shortage rate. This can accurately adjust the amount of refrigerant in the multi-split system while avoiding the impact of high-voltage frequency limiting due to excessive exhaust pressure on performance, thereby greatly improving the customer experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a multi-link system according to an embodiment of the present application.

[0031] Figure 2 It is a flow chart of a method for controlling the amount of refrigerant in a multi-split system operating with a single indoor unit according to an embodiment of the present application.

[0032] Figure 3 It is a schematic diagram of a method for controlling the amount of refrigerant in a multi-split system operating with a single indoor unit according to an embodiment of the present application.

[0033] Figure 4 It is a schematic diagram of a device for controlling the amount of refrigerant in a multi-split system operating with a single indoor unit according to an embodiment of the present application. DETAILED DESCRIPTION

[0034] The following, in conjunction with the accompanying drawings, describes in detail the method and device for controlling the amount of refrigerant in a multi-split system with single floor heating operation provided in the embodiment of the present application through specific embodiments and their application scenarios.

[0035] For the sake of convenience, the following example uses the single floor heating operation as the single indoor unit operation. Figure 1 The structure of the multi-split system is described below. The multi-split system is also called a multi-split air conditioning unit, which consists of an outdoor unit 101 and multiple indoor units, wherein the outdoor unit includes a compressor 102 for driving the refrigerant to circulate in the system, and the indoor unit generally includes multiple air conditioners, such as air conditioners 103a~103n, and a single floor heating, such as floor heating 104, and each indoor unit is provided with an electronic expansion valve, such as electronic expansion valves 105a~105n+1, for adjusting the amount of refrigerant involved in the circulation of the indoor unit. When the multi-split system is used for heating, that is, only a single floor heating is running in the indoor unit, and the other indoor units are in a dormant state, the opening of the electronic expansion valves 105a~105n in the dormant room will also change accordingly, so that the refrigerant stored in the dormant room participates in the system circulation, thereby adjusting the floor heating temperature. Among them, the refrigerant stored in the dormant room is liquid, and the refrigerant circulating in the system is liquid and gaseous, which changes alternately to control the temperature by absorbing and releasing heat.

[0036] Next reference Figure 2 The flowchart is used to illustrate the method of controlling the amount of refrigerant in the multi-split system when single floor heating is running.

[0037] In step 201, the exhaust pressure and exhaust temperature of the compressor of the outdoor unit are obtained. In the conventional control method, only the exhaust temperature is considered, which will cause the exhaust pressure to be too high when the refrigerant is continuously added to the system cycle when the exhaust pressure is too high, and the high pressure frequency of the outdoor unit is limited, thus affecting the performance. Therefore, the exhaust pressure and the exhaust temperature are comprehensively considered to avoid this problem.

[0038] In step 202, the refrigerant shortage rate of the multi-split system is obtained. The refrigerant shortage rate is only a description of whether the amount of refrigerant circulating in the system is appropriate when the system is running. It is a control value used only for refrigerant quantity control, and is not a description of the specific refrigerant content in the system. Therefore, even if the current temperature control of the multi-split system is appropriate, the refrigerant shortage rate may not be 0. In other words, when the refrigerant shortage rate is greater than zero, it can also be considered that the amount of refrigerant circulating in the current system is appropriate. In one embodiment, the refrigerant shortage rate calculation formula is as follows:

[0039] Rh(n)=1.0-P1%

[0040] Among them, Rh(n) is the refrigerant shortage rate, and P1% is the pressure ratio. The pressure ratio is obtained by the following formula:

[0041] P1%=(PL-Ps) / (Pd-Ps)×m+n

[0042] Among them, PL is the saturated pressure in the liquid pipe (i.e., the pipe for transporting refrigerant) obtained by the liquid pipe temperature of the multi-split system, Ps is the suction pressure of the compressor, Pd is the exhaust pressure, and m and n are compensation constants. In addition, through a large number of experiments, it can be obtained that the optimal value of m is 1.23 and the optimal value of n is 0.24. The control accuracy of this control method is higher under the optimal values ​​of m and n.

[0043] In step 203, the opening of the electronic expansion valve of the multiple indoor units that are not in operation is controlled based on the exhaust pressure, exhaust temperature and refrigerant shortage rate to adjust the amount of refrigerant circulating in the multi-split system. When the opening of the electronic expansion valve is opened, the amount of refrigerant entering the system circulation in the idle room increases; when the opening of the electronic expansion valve is closed, the amount of refrigerant entering the system circulation in the idle room decreases. By controlling the opening of the electronic expansion valve by comprehensively considering the exhaust pressure of the compressor, the exhaust temperature and the refrigerant shortage rate of the system, control can be performed on the basis of controlling various parameters within a reasonable range.

[0044] In one embodiment, the rest room may be controlled in the following manners, including:

[0045] When the exhaust temperature is greater than the first temperature threshold and / or the refrigerant shortage rate is greater than the first refrigerant threshold, the electronic expansion valve opening of the rest room is increased. At this time, the exhaust temperature being greater than the first temperature threshold and the refrigerant shortage rate being greater than the first refrigerant threshold can both reflect that the current heating supply of the floor heating is too high, and refrigerant needs to be added to the system for cooling. Therefore, the refrigerant in the rest room is added to the system by increasing the opening of the electronic expansion valve.

[0046] When the exhaust temperature is greater than the second temperature threshold, less than or equal to the first temperature threshold, and the exhaust pressure is less than or equal to the pressure threshold, the opening of the electronic expansion valves of multiple indoor units that are not in operation is increased; when the exhaust temperature is greater than the second temperature threshold, less than or equal to the first temperature threshold, and the exhaust pressure is greater than the pressure threshold, the opening of the electronic expansion valves of multiple indoor units remains unchanged. When the exhaust temperature is greater than the second temperature threshold, it means that the current heating supply of the floor heating is high, but when the exhaust pressure is greater than the pressure threshold, if the opening of the electronic expansion valve is increased only because the exhaust temperature is greater than the second temperature threshold, the exhaust pressure will be too high and the compressor will be reduced. Therefore, the opening of the electronic expansion valve will be increased only when the exhaust pressure is less than the pressure threshold, and when the exhaust pressure is greater than the pressure threshold, the opening remains unchanged, but the temperature threshold is increased (that is, the aforementioned first temperature threshold is used for judgment) to delay the time for the electronic expansion valve to be opened, so that the exhaust pressure will not increase to cause the compressor to reduce the frequency at high pressure.

[0047] When the exhaust temperature is less than or equal to the third temperature threshold, and the refrigerant shortage rate is less than or equal to the second refrigerant threshold, the electronic expansion valve openings of multiple indoor units that are not in operation are closed; when the exhaust temperature is greater than the third temperature threshold, less than or equal to the second temperature threshold and / or the exhaust temperature is less than or equal to the third temperature threshold, and the refrigerant shortage rate is greater than the second refrigerant threshold, the electronic expansion valve openings of multiple indoor units remain unchanged. When the exhaust temperature is low enough and the refrigerant shortage rate is small enough, closing the electronic expansion valve opening can accumulate excess refrigerant in the indoor unit, thereby reducing the pressure of the system, reducing power consumption, and improving energy efficiency.

[0048] Next reference Figure 3 The above control method is described with reference to a specific embodiment shown in FIG.

[0049] In step 301, the working mode of the multi-split system is determined. When only the floor heating module is operating, it is determined that the condition is met and the electronic expansion valve opening correction control is enabled.

[0050] In step 302, determine whether the refrigerant shortage rate is greater than 30%. When the refrigerant shortage rate is greater than 30%, it is considered that there is a lack of refrigerant in the existing cycle of the system, that is, the opening of the electronic expansion valve in the idle chamber is controlled to increase by 15pls every five minutes; when the refrigerant shortage rate is less than or equal to 30%, the exhaust temperature is determined.

[0051] In step 303, it is determined whether the exhaust temperature is greater than 90°C, and the exhaust temperature is further determined according to the determination result, wherein TD is the exhaust temperature.

[0052] When the exhaust temperature is greater than 90°C, it is also determined that there is a lack of refrigerant in the existing system cycle. However, if the exhaust pressure is too high at this time, directly controlling the opening of the electronic expansion valve in the rest room to increase will cause the exhaust pressure to continue to rise, and then exceed the normal working pressure limit, resulting in high-pressure frequency limiting of the compressor, affecting the performance of the multi-split system. Therefore, when the exhaust temperature is greater than 90°C, step 304 is performed to determine whether the exhaust temperature is greater than 95°C. This step is equivalent to raising the temperature threshold for controlling the opening of the electronic expansion valve in the rest room. Only when the exhaust temperature is greater than a higher temperature threshold of 95°C, the electronic expansion valve in the rest room will be controlled to open 15pls every five minutes to delay the opening time of the electronic expansion valve in the rest room, so that excessive refrigerant will not be discharged into the system cycle, resulting in high-pressure frequency limiting of the compressor. When the exhaust temperature is greater than 90°C and less than 95°C, step 305 is performed to determine whether the exhaust pressure is greater than 32kgf / cm2. When the exhaust pressure is greater than 32kgf / cm2, it is considered that the current exhaust pressure is too high, so the current opening of the electronic expansion valve in the rest room is maintained unchanged; when the exhaust pressure is less than or equal to 32kgf / cm2, the opening of the electronic expansion valve in the rest room can be controlled to increase by 15pls every five minutes to supply more refrigerant to the multi-split system and reduce the current exhaust temperature.

[0053] When the exhaust temperature is less than or equal to 90°C, step 306 is performed to determine whether the exhaust temperature is less than or equal to 85°C. When the exhaust temperature is greater than 85°C and less than or equal to 90°C, it means that the amount of refrigerant circulating in the current system is appropriate, so the current opening of the electronic expansion valve in the rest room is maintained unchanged; when the exhaust temperature is less than or equal to 85°C, step 307 is performed to determine whether the refrigerant shortage rate is less than or equal to 15%. When the exhaust temperature is less than or equal to 85°C, it is considered that the amount of refrigerant circulating in the current system may be excessive, so the refrigerant shortage rate is further determined. When the refrigerant shortage rate is less than or equal to 15%, it can be considered that the amount of refrigerant circulating in the current system is too much, so the opening of the electronic expansion valve in the rest room is controlled to be closed by 15pls every five minutes to accumulate excessive circulating refrigerant in the rest room, reduce system pressure and power consumption, and improve energy efficiency; when the refrigerant shortage rate is less than or equal to 30% and greater than 15%, it is considered that the current amount of refrigerant is appropriate, so the current opening of the electronic expansion valve in the rest room is maintained unchanged.

[0054] It can be understood that the actual values ​​of the various thresholds used in the above embodiments are preferred thresholds for one or more models of multi-split systems obtained based on a large number of experiments and theoretical reasoning, and the selection of the equal sign in the inequality judgment can be changed according to the situation. For other types of multi-split systems or usage environments, other thresholds or other order threshold judgment processes can also be used. The core invention of this scheme is to introduce the judgment of the sum of the refrigerant deficiency rate and the compressor exhaust temperature and exhaust pressure of the multi-split system to control the opening of the electronic expansion valve in the rest chamber, and then, under the condition of ensuring the normal operation of the multi-split system, the refrigerant in the control system is in a suitable state, so that the multi-split system can control the ambient temperature at a suitable point or a specified point.

[0055] refer to Figure 4 The present application also proposes a device 400 for controlling the amount of refrigerant in a multi-split system with a single indoor unit, wherein the multi-split system includes an outdoor unit and multiple indoor units, wherein the multiple indoor units include floor heating and air conditioning, wherein only a single indoor unit is in operation, and the device 400 includes:

[0056] The parameter acquisition unit 401 is used to acquire the exhaust pressure and exhaust temperature of the compressor of the external unit;

[0057] The parameter calculation unit 402 is used to obtain the refrigerant shortage rate of the multi-split system;

[0058] The control unit 403 is used to control the opening of the electronic expansion valves of multiple indoor units that are not in operation based on the exhaust pressure, exhaust temperature and refrigerant deficiency rate, so as to adjust the amount of refrigerant circulating in the multi-split system.

[0059] The device 400 can be run on various computers and servers, and can use the aforementioned method to control the amount of refrigerant circulating in the multi-split system.

[0060] The above specific embodiments illustrate the implementation of the present application, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Although the description of the present application will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to the implementation. In addition, in order to avoid confusion or blurring the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0061] Furthermore, various operations will be described as multiple discrete operations in a manner that is most helpful for understanding the illustrative embodiments; however, the order of description should not be construed as implying that these operations are necessarily order dependent. In particular, these operations do not need to be performed in the order presented.

[0062] Unless the context dictates otherwise, the terms "comprising," "having," and "including" are synonymous. The phrase "A / B" means "A or B." The phrase "A and / or B" means "(A and B) or (A or B)."

[0063] As used herein, the term "module" or "unit" may refer to, be or include: an application specific integrated circuit (ASIC), an electronic circuit, a (shared, dedicated or group) processor and / or memory that executes one or more software or firmware programs, a combinational logic circuit and / or other suitable components that provide the described functionality.

[0064] In the accompanying drawings, some structural or method features are shown in a specific arrangement and / or order. However, it should be understood that such a specific arrangement and / or order may not be required. In some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. In addition, the inclusion of structural or method features in a specific figure does not mean that such features are required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0065] It should be understood that although the terms "first", "second", etc. may be used here to describe various units or data, these units or data should not be limited by these terms. These terms are used only to distinguish one feature from another. For example, without departing from the scope of the exemplary embodiment, a first feature may be referred to as a second feature, and similarly, a second feature may be referred to as a first feature.

[0066] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0067] While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

1. A method for controlling the amount of refrigerant in a multi-split system with a single indoor unit, the multi-split system comprising an outdoor unit and a plurality of indoor units, the plurality of indoor units comprising floor heating and air conditioning, wherein: Only a single indoor unit is in operation, and the characteristics include: Obtaining the exhaust pressure and exhaust temperature of the compressor of the external unit; Obtaining a refrigerant shortage rate of the multi-split system; The opening degrees of the electronic expansion valves of the plurality of indoor units that are not in operation are controlled based on the exhaust pressure, the exhaust temperature, and the refrigerant deficiency rate to adjust the amount of refrigerant circulating in the multi-split system.

2. The method according to claim 1, characterized in that: Controlling the opening of the electronic expansion valves of the plurality of indoor units that are not in operation based on the exhaust pressure, the exhaust temperature, and the refrigerant deficiency rate includes: When the exhaust temperature is greater than a first temperature threshold and / or the refrigerant shortage rate is greater than a first refrigerant threshold, increasing the opening of the electronic expansion valves of the plurality of indoor units that are not in operation; When the exhaust temperature is greater than the second temperature threshold and less than or equal to the first temperature threshold, and the exhaust pressure is greater than the pressure threshold, the openings of the electronic expansion valves of the multiple indoor units remain unchanged; When the exhaust temperature is greater than the second temperature threshold and less than or equal to the first temperature threshold, and the exhaust pressure is less than or equal to the pressure threshold, increasing the opening of the electronic expansion valves of the multiple indoor units that are not in operation; When the exhaust temperature is less than or equal to a third temperature threshold, and the refrigerant shortage rate is less than or equal to a second refrigerant threshold, reducing the opening of the electronic expansion valves of the plurality of indoor units that are not in operation; When the exhaust temperature is greater than the third temperature threshold and less than or equal to the second temperature threshold and / or the exhaust temperature is less than or equal to the third temperature threshold, and the refrigerant deficiency rate is greater than the second refrigerant threshold, the opening of the electronic expansion valves of the multiple indoor units remains unchanged.

3. The method according to claim 2, characterized in that The first refrigerant threshold is 30% and / or the second refrigerant threshold is 15%.

4. The method according to claim 2, characterized in that: The first temperature threshold is 95°C and / or the second temperature threshold is 90°C and / or the third temperature threshold is 85°C.

5. The method according to claim 2, characterized in that: The pressure threshold is 32kgf / cm2.

6. The method according to claim 2, characterized in that When the opening degrees of the electronic expansion valves of the plurality of indoor units that are not in operation are increased or decreased, the rate of change of the opening degrees is increased or decreased by 15 pls every five minutes.

7. The method according to claim 6, characterized in that The upper limit of the opening is 180 pls, and the lower limit is 60 pls.

8. The method according to claim 2, characterized in that: The refrigerant shortage rate is obtained by the following formula: Rh(n)=1.0-P1% Wherein, Rh(n) is the refrigerant shortage rate, P1% is the pressure ratio, and the pressure ratio is obtained by the following formula: P1%=(PL-Ps) / (Pd-Ps)×m+n Among them, PL is the saturated pressure in the liquid pipe obtained by the liquid pipe temperature of the multi-split system, Ps is the suction pressure of the compressor, Pd is the exhaust pressure, and m and n are compensation constants.

9. A device for controlling the amount of refrigerant in a multi-split system with a single indoor unit, the multi-split system comprising an outdoor unit and a plurality of indoor units, the plurality of indoor units comprising floor heating and air conditioning, wherein: Only a single indoor unit is in operation, and the characteristics include: A parameter acquisition unit, used to acquire the exhaust pressure and exhaust temperature of the compressor of the external unit; A parameter calculation unit, used to obtain a refrigerant shortage rate of the multi-split system; A control unit is used to control the opening of the electronic expansion valves of the multiple indoor units that are not in operation based on the exhaust pressure, the exhaust temperature and the refrigerant deficiency rate to adjust the amount of refrigerant circulating in the multi-split system.

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