Supercooling valve control method, device and multi-split system

Abstract

The application provides a supercooling valve control method, device and multi-connected system; the method comprises the following steps: periodically acquiring operation parameters after all outdoor units are operated for a preset length of time; the operation parameters comprise an indoor superheat, an exhaust temperature, an exhaust superheat and a target pipe temperature corresponding supercooling valve opening; determining a control mode of the supercooling valve in the current period according to the exhaust temperature and a preset temperature threshold; in the control mode, determining a target opening corresponding to the current period according to the operation parameters and a preset superheat threshold; and controlling the supercooling valve to operate according to the target opening in the current period. In the control mode, different control modes of the supercooling valve are determined according to the exhaust temperature, and in the control mode, the opening of the supercooling valve is intelligently controlled according to the supercooling valve opening, the exhaust superheat and the indoor superheat, so that the exhaust of the multi-connected system is stable, the output is maximum, and the operation effect of the multi-connected system is improved.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to a subcooling valve control method, device, and multi-split air conditioning system. Background Technology

[0002] For the subcooling valve of a multi-split air conditioning unit (i.e., a multi-split air conditioning unit), control is mainly based on the degree of subcooling. Specifically, a target subcooling degree (value or range) is set. When the actual subcooling degree is less than the target subcooling degree, the opening of the subcooling valve is increased; when the actual subcooling degree is greater than the target subcooling degree, the opening of the subcooling valve is decreased. With sufficient subcooling, the target supercooling degree is generally set relatively high. As the opening of the subcooling valve increases, liquid will return, causing the valve opening to decrease. This decrease in opening leads to insufficient subcooling, causing the opening to increase again, and so on. In addition, the subcooling valve is also controlled by the exhaust gas. For example, when the exhaust gas temperature is high, the subcooling valve is forcibly opened to lower the exhaust gas temperature; when the exhaust gas temperature decreases, the subcooling valve returns to normal control.

[0003] While the above solution can control the subcooling valve, it has the following problems: a fixed target subcooling degree may not be applicable to different operating conditions and systems. For example, if the opening of the subcooling valve is too large, or if the opening is forcibly increased to reduce the exhaust temperature until the exhaust temperature drops to a low level before closing, the opening of the subcooling valve will be too large, resulting in insufficient refrigerant in the main circuit, which will reduce the capacity output of the multi-split system and thus affect the operating performance of the multi-split system. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a subcooling valve control method, device and multi-split air conditioning system to alleviate the above problems. The subcooling valve opening is intelligently controlled based on the subcooling valve opening, exhaust superheat and indoor unit superheat, so that the exhaust of the multi-split air conditioning system is stable and the output is maximized, thereby improving the operating effect of the multi-split air conditioning system.

[0005] In a first aspect, embodiments of the present invention provide a subcooling valve control method applied to a multi-split air conditioning system; wherein the multi-split air conditioning system includes multiple outdoor units and multiple indoor units; the method includes: periodically acquiring operating parameters after all outdoor units have been running in cooling mode for a preset time; wherein the operating parameters include: the superheat of the indoor unit corresponding to each operating indoor unit, the exhaust temperature and exhaust superheat of the compressor in each outdoor unit, and the opening degree of the subcooling valve corresponding to a target pipe temperature, wherein the target pipe temperature is used to characterize the minimum pipe temperature of the middle pipe of the indoor heat exchanger in the indoor unit; determining the control mode of the subcooling valve in the current cycle based on the exhaust temperature and a preset temperature threshold; wherein the control mode includes a first control mode and a second control mode, wherein the first control mode is used to characterize the mode of controlling the subcooling valve according to a preset target subcooling, and the second control mode is used to characterize the mode of controlling the subcooling valve according to the exhaust temperature; in the control mode, the target opening degree corresponding to the current cycle is determined based on the operating parameters and the preset superheat threshold; and the subcooling valve is controlled to operate at the target opening degree in the current cycle.

[0006] In the above-mentioned subcooling valve control method, different control modes of the subcooling valve are determined according to the exhaust temperature. In the control mode, the opening of the subcooling valve is intelligently controlled according to the subcooling valve opening, exhaust superheat and indoor unit superheat, so that the exhaust of the multi-split system is stable and the output is maximized, thereby improving the operating effect of the multi-split system.

[0007] Preferably, the step of determining the control mode of the subcooling valve in the current cycle based on the exhaust temperature and the preset temperature threshold includes: if the exhaust temperature is not greater than the preset temperature threshold, determining the control mode of the subcooling valve corresponding to the compressor in the current cycle as the first control mode; or, if the exhaust temperature is greater than the preset temperature threshold, determining the control mode of the subcooling valve corresponding to the compressor in the current cycle as the second control mode.

[0008] Preferably, in the control method described above, the step of determining the target opening degree corresponding to the current cycle based on the operating parameters and the preset superheat threshold includes: if the control method is the first control method, obtaining historical parameters prior to the current cycle; wherein, the historical parameters include: the first historical parameter corresponding to the previous cycle, the second historical parameter corresponding to the cycle before that, and the third historical parameter corresponding to the cycle before that; determining the target opening degree corresponding to the current cycle based on the historical parameters and the superheat threshold.

[0009] Preferably, the superheat thresholds include a first superheat threshold, a second superheat threshold, and a third superheat threshold; the first historical parameters include: the first indoor unit superheat, the first exhaust superheat, and the opening degree of the first subcooling valve corresponding to the target pipe temperature in the previous cycle; the second historical parameters include: the second indoor unit superheat, the second exhaust superheat, and the opening degree of the second subcooling valve corresponding to the target pipe temperature in the cycle two weeks prior; the third historical parameters include: the third indoor unit superheat, the third exhaust superheat, and the opening degree of the third subcooling valve corresponding to the target pipe temperature in the cycle two weeks prior; the step of determining the target opening degree corresponding to the current cycle based on the historical parameters and the superheat thresholds includes: if the first indoor unit superheat, the second indoor unit superheat, and the third indoor unit superheat are all equal to the first superheat threshold, and the first exhaust superheat, the second exhaust superheat, and the third exhaust superheat are all greater than the second superheat threshold, the target opening degree corresponding to the current cycle is calculated based on the opening degrees of the first subcooling valve, the second subcooling valve, and the third subcooling valve.

[0010] Preferably, the step of calculating the target opening degree corresponding to the current cycle based on the opening degree of the first subcooling valve, the opening degree of the second subcooling valve, and the opening degree of the third subcooling valve includes: the calculation formula for the target opening degree is as follows: Pa=(P1+P2+P3) / 3; where Pa represents the target opening degree, P1 represents the opening degree of the first subcooling valve, P2 represents the opening degree of the second subcooling valve, and P3 represents the opening degree of the third subcooling valve.

[0011] Preferably, in the above-mentioned control method, the step of determining the target opening degree corresponding to the current cycle based on the operating parameters and the preset superheat threshold further includes: when the control method is the second control method, if the exhaust temperature of the current cycle is less than the exhaust temperature of the previous cycle, and the indoor unit superheat degree of the current cycle is equal to the third superheat threshold, and the exhaust superheat degree of the current cycle is greater than the second superheat threshold, then the opening degree of the first subcooling valve corresponding to the target pipe temperature in the previous cycle is taken as the target opening degree corresponding to the current cycle.

[0012] Preferably, the above-mentioned step of periodically acquiring operating parameters includes: acquiring the inlet temperature and outlet temperature of the indoor heat exchanger in each cycle, and calculating the indoor unit superheat based on the inlet temperature and outlet temperature; and acquiring the saturation temperature corresponding to the high pressure in the outdoor unit, and calculating the exhaust superheat of the compressor in the outdoor unit based on the exhaust temperature and the saturation temperature.

[0013] Secondly, embodiments of the present invention also provide a subcooling valve control device applied to a multi-split air conditioning system; wherein the multi-split air conditioning system includes multiple outdoor units and multiple indoor units; the device includes: a parameter acquisition module, used to periodically acquire operating parameters after all outdoor units have been running in cooling mode for a preset time; wherein the operating parameters include: the superheat of the indoor unit corresponding to each operating indoor unit, the exhaust temperature and exhaust superheat of the compressor in each outdoor unit, and the opening degree of the subcooling valve corresponding to the target pipe temperature, the target pipe temperature being used to characterize the minimum pipe temperature of the middle pipe of the indoor heat exchanger in the indoor unit; a first determination module, used to determine the control mode of the subcooling valve in the current cycle based on the exhaust temperature and a preset temperature threshold, the first control mode being used to characterize the mode of controlling the subcooling valve according to a preset target subcooling, and the second control mode being used to characterize the mode of controlling the subcooling valve according to the exhaust temperature; wherein the control mode includes the first control mode and the second control mode; a second determination module, used to determine the target opening degree corresponding to the current cycle based on the operating parameters and the preset superheat threshold in the control mode; and a control operation module, used to control the subcooling valve to operate at the target opening degree in the current cycle.

[0014] Thirdly, embodiments of the present invention also provide a multi-unit system, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described in the first aspect.

[0015] Fourthly, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the method described in the first aspect.

[0016] The embodiments of the present invention bring the following beneficial effects:

[0017] This invention provides a subcooling valve control method, device, and multi-split air conditioning system. After all outdoor units have been running for a preset refrigeration period, operating parameters are periodically acquired. These operating parameters include: the superheat of each operating indoor unit, the exhaust temperature and exhaust superheat of the compressor in each outdoor unit, and the subcooling valve opening corresponding to a target pipe temperature. The target pipe temperature is the minimum pipe temperature characterizing the central pipe temperature of the indoor heat exchanger in the indoor unit. Based on the exhaust temperature and a preset temperature threshold, the control mode of the subcooling valve in the current cycle is determined. In this control mode, the target opening corresponding to the current cycle is determined based on the operating parameters and the preset superheat threshold. The subcooling valve is controlled to operate at the target opening in the current cycle. In this control mode, different control modes for the subcooling valve are determined based on the exhaust temperature. Furthermore, the opening of the subcooling valve is intelligently controlled based on the subcooling valve opening, exhaust superheat, and indoor unit superheat, resulting in stable exhaust and maximum output in the multi-split air conditioning system, thus improving the overall operating performance of the system.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 A flowchart of a subcooling valve control method provided in an embodiment of the present invention;

[0022] Figure 2 A flowchart of another subcooling valve control method provided in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of a multi-unit air conditioning system provided in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of a subcooling valve control device provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of another multi-unit system provided in an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] To facilitate understanding of this embodiment, the embodiments of the present invention will be described in detail below.

[0028] Example 1:

[0029] This invention provides a subcooling valve control method applied to a multi-split air conditioning system; wherein the multi-split air conditioning system includes multiple outdoor units and multiple indoor units; such as Figure 1 As shown, the method includes the following steps:

[0030] Step S102: After all outdoor units have been running for a preset time, the operating parameters are periodically acquired. The operating parameters include: the superheat of the indoor unit corresponding to each operating indoor unit, the exhaust temperature and exhaust superheat of the compressor in each outdoor unit, and the opening degree of the subcooling valve corresponding to the target pipe temperature.

[0031] In practical applications, multi-split air conditioning systems are equipped with a controller and multiple temperature acquisition devices, such as temperature sensors or temperature bulbs, that communicate with the controller to collect the temperature at designated locations. These temperature acquisition devices include, but are not limited to, a first temperature sensor located at the inlet of the indoor heat exchanger, a second temperature sensor located at the outlet of the indoor heat exchanger, a third temperature sensor located on the coil in the middle of the indoor heat exchanger, and a fourth temperature sensor located at the compressor exhaust port. The specific locations of these temperature acquisition devices can be configured according to actual conditions.

[0032] The process of periodically acquiring operating parameters is as follows: In each cycle, the inlet and outlet temperatures of the indoor heat exchanger are acquired, and the superheat of the indoor unit is calculated based on the inlet and outlet temperatures; and the saturation temperature corresponding to the high pressure in the outdoor unit is acquired, and the exhaust superheat of the compressor in the outdoor unit is calculated based on the exhaust temperature and the saturation temperature.

[0033] Specifically, in each cycle, for each operating indoor unit, the controller acquires the inlet temperature of the indoor heat exchanger from the first temperature sensor, the outlet temperature from the second temperature sensor, and the middle pipe temperature from the third temperature sensor. Based on the inlet and outlet temperatures, the controller calculates the indoor unit superheat of the heat exchanger. Simultaneously, the minimum middle pipe temperature within the cycle is used as the target pipe temperature, representing the minimum temperature at which the middle pipe of the indoor heat exchanger is located. The controller also acquires the corresponding subcooling valve opening for the target pipe temperature. Furthermore, for each of the operating outdoor units, the controller acquires the exhaust temperature from the fourth temperature sensor located at the compressor exhaust port. Based on the exhaust temperature and saturation temperature, the controller calculates the exhaust superheat of the compressor. For example, the exhaust temperature minus the saturation temperature corresponding to the high-pressure pressure equals the compressor's exhaust superheat.

[0034] It should be noted that the calculation process for the superheat of each indoor unit and the exhaust superheat of the compressor in each outdoor unit can refer to existing technologies, and will not be elaborated in detail here. Furthermore, the preset duration is preferably 10 minutes, and each cycle is preferably 40 seconds. The specific preset duration and cycle time can be set according to actual conditions.

[0035] Step S104: Determine the control mode of the subcooling valve in the current cycle based on the exhaust temperature and the preset temperature threshold.

[0036] The control methods include a first control method and a second control method. The first control method is used to characterize the method of controlling the subcooling valve according to the preset target subcooling degree. For example, when the actual subcooling degree is less than the target subcooling degree, the opening degree of the subcooling valve is increased, and vice versa. The second control method is used to characterize the method of forcibly controlling the subcooling valve according to the exhaust temperature. That is, when the exhaust temperature is high, the subcooling valve is forcibly opened to reduce the exhaust temperature, and when the exhaust temperature decreases, the subcooling valve returns to normal control.

[0037] Specifically, if the exhaust temperature is not greater than a preset temperature threshold, the control mode for the subcooling valve corresponding to the compressor in the current cycle is determined to be the first control mode; that is, when the exhaust temperature of the subcooling valve is low, the subcooling valve is controlled according to the target subcooling degree. Alternatively, if the exhaust temperature is greater than the preset temperature threshold, the control mode for the subcooling valve corresponding to the compressor in the current cycle is determined to be the second control mode; that is, when the exhaust temperature of the subcooling valve is high, the subcooling valve is forcibly controlled according to the exhaust temperature. Therefore, determining the control mode corresponding to the subcooling valve according to different exhaust temperature scenarios improves the opening control accuracy of the subcooling valve, thereby ensuring the operating effect of the multi-split air conditioning system.

[0038] It should be noted that for multiple outdoor units in a multi-split air conditioning system, the control method of the subcooling valve in each outdoor unit is determined based on the discharge temperature of the compressor in that outdoor unit. For example, if the multi-split air conditioning system includes a first outdoor unit and a second outdoor unit, and the discharge temperature of the compressor in the first outdoor unit is not greater than a preset temperature threshold, then the opening of the subcooling valve in the first outdoor unit is controlled according to the first control method in the current cycle. Similarly, if the discharge temperature of the compressor in the second outdoor unit is greater than the preset temperature threshold, then the opening of the subcooling valve in the second outdoor unit is controlled according to the second control method in the current cycle. Thus, the control method of the subcooling valve in the outdoor unit is determined based on the discharge temperature of the compressor, ensuring the control accuracy of each subcooling valve.

[0039] Step S106: In the control mode, the target opening degree corresponding to the current cycle is determined according to the operating parameters and the preset superheat threshold.

[0040] Specifically, after determining the control mode of the subcooling valve in the current cycle based on the exhaust temperature, the target opening degree corresponding to the current cycle is also determined based on the operating parameters of the current cycle and the preset superheat threshold. That is, the opening degree of the subcooling valve is intelligently controlled together based on three parameters: the opening degree of the subcooling valve, the exhaust superheat degree, and the indoor unit superheat degree in the current cycle. Compared with the method of controlling the subcooling valve alone, the method of intelligent control of multiple parameters not only ensures the stability of the exhaust of the multi-split system, but also ensures the maximum output of the multi-split system, thereby improving the operating effect of the multi-split system.

[0041] Step S108: Control the subcooling valve to operate at the target opening degree in the current cycle.

[0042] The subcooling valve control method provided in this invention determines different control modes of the subcooling valve based on the exhaust temperature. In the control mode, the opening of the subcooling valve is intelligently controlled based on the subcooling valve opening, exhaust superheat, and indoor unit superheat, so that the exhaust of the multi-split system is stable and the output is maximized. This not only improves the operating effect of the multi-split system, but also improves the control accuracy of the subcooling valve.

[0043] In one implementation, if the control method is the first control method, the process of determining the target opening degree corresponding to the current cycle based on the operating parameters and the preset superheat threshold in the control method is as follows: obtaining historical parameters before the current cycle; wherein, the historical parameters include: the first historical parameter corresponding to the previous cycle, the second historical parameter corresponding to the cycle before that, and the third historical parameter corresponding to the cycle before that; determining the target opening degree corresponding to the current cycle based on the historical parameters and the superheat threshold.

[0044] The superheat thresholds mentioned above include a first superheat threshold, a second superheat threshold, and a third superheat threshold; the first historical parameters include: the first indoor unit superheat, the first exhaust superheat, and the first subcooling valve opening corresponding to the target pipe temperature in the previous cycle; here, the first indoor unit superheat includes the indoor unit superheat corresponding to each operating indoor unit in the previous cycle, the first exhaust superheat includes the exhaust superheat corresponding to the compressor of each outdoor unit in all operating outdoor units in the previous cycle, and the first subcooling valve opening refers to the subcooling valve opening corresponding to the target pipe temperature in the previous cycle. Similarly, the second historical parameters include: the second indoor unit superheat, the second exhaust superheat, and the second subcooling valve opening corresponding to the target pipe temperature in the previous cycle; wherein, the second indoor unit superheat includes the indoor unit superheat corresponding to the previous cycle for each operating indoor unit, the second exhaust superheat includes the exhaust superheat corresponding to the compressor of each operating outdoor unit in the previous cycle, and the second subcooling valve opening refers to the subcooling valve opening corresponding to the target pipe temperature in the previous cycle. And, the third historical parameters include: the third indoor unit superheat, the third exhaust superheat, and the third subcooling valve opening corresponding to the target pipe temperature in the cycle two years prior; wherein, the third indoor unit superheat includes the indoor unit superheat corresponding to the cycle two years prior, the third exhaust superheat includes the exhaust superheat corresponding to the compressor of each operating outdoor unit in the cycle two years prior, and the third subcooling valve opening refers to the subcooling valve opening corresponding to the target pipe temperature in the cycle two years prior.

[0045] Specifically, if the superheat of the first indoor unit, the superheat of the second indoor unit, and the superheat of the third indoor unit are all equal to the first superheat threshold, and the superheat of the first exhaust, the superheat of the second exhaust, and the superheat of the third exhaust are all greater than the second superheat threshold, then the target opening degree corresponding to the current cycle is calculated based on the opening degree of the first subcooling valve, the opening degree of the second subcooling valve, and the opening degree of the third subcooling valve.

[0046] For clarity, let's take one outdoor unit as an example. If the superheat values ​​of the first, second, and third indoor units are all equal to the first superheat threshold, and the superheat values ​​of the first, second, and third discharge units of the outdoor unit's compressor are all greater than the second superheat threshold, then the target opening degree of the outdoor unit's compressor in the current cycle can be calculated based on the opening degrees of the first, second, and third subcooling valves. The formula for calculating the target opening degree is as follows:

[0047] Pa = (P1 + P2 + P3) / 3

[0048] Where Pa represents the target opening degree, P1 represents the opening degree of the first subcooling valve, P2 represents the opening degree of the second subcooling valve, and P3 represents the opening degree of the third subcooling valve.

[0049] Therefore, for the three consecutive historical cycles preceding the current cycle, namely the previous cycle, the cycle before that, and the cycle before that; if the following conditions are met: ① In the previous cycle, the first superheat of all indoor units equals the first superheat threshold, and the first discharge superheat of the outdoor unit's compressor is greater than the second superheat threshold, and the opening degree of the first subcooling valve corresponding to the target pipe temperature in the outdoor unit in the previous cycle is P1; ② In the cycle before that, the second superheat of all indoor units equals the first superheat threshold, and the second discharge superheat of the outdoor unit's compressor is greater than the second superheat threshold. If the exhaust superheat is greater than the second superheat threshold, the opening degree of the second subcooling valve in the outdoor unit corresponding to the target pipe temperature in the previous cycle is P2; ③ In the cycle two weeks prior, the third indoor unit superheat of all indoor units equals the first superheat threshold, and the third exhaust superheat of the compressor of the outdoor unit is greater than the second superheat threshold, the opening degree of the third subcooling valve in the outdoor unit corresponding to the target pipe temperature in the previous cycle is P3; then the target opening degree of the subcooling valve of the outdoor unit in the current cycle is Pa, and the subcooling valve is controlled to operate at the target opening degree Pa in subsequent cycles.

[0050] Therefore, for the subcooling valve of each outdoor unit, when the exhaust temperature is low, the subcooling valve is controlled according to the first control mode. In this control mode, it is detected that the indoor unit superheat is in the optimal state at a certain opening degree, the exhaust superheat meets the requirement of no liquid return, and the indoor unit target pipe temperature is the lowest, indicating that the multi-split system output is the maximum at this time. Therefore, the subcooling valve is controlled to operate according to the calculated target opening degree, and it operates according to the target opening degree in subsequent cycles until the control mode is changed, and the subcooling valve is controlled according to the changed control mode.

[0051] In one implementation, when the control mode is the second control mode, the process of determining the target opening degree corresponding to the current cycle based on the operating parameters and the preset superheat threshold in the control mode is as follows: if the exhaust temperature of the current cycle is less than the exhaust temperature of the previous cycle, and the indoor unit superheat degree of the current cycle is equal to the third superheat threshold, and the exhaust superheat degree of the current cycle is greater than the second superheat threshold, then the opening degree of the first subcooling valve corresponding to the target pipe temperature in the previous cycle is taken as the target opening degree corresponding to the current cycle.

[0052] Specifically, for the second control method, if the exhaust temperature of the current cycle is lower than that of the previous cycle, the exhaust temperature decreases, indicating that the opening of the subcooling valve can maintain the stability of the exhaust. When the indoor unit superheat equals the third superheat threshold and the exhaust superheat is greater than the second superheat threshold, it means that the indoor unit superheat and exhaust superheat meet the requirement of not causing severe liquid return. Therefore, the opening of the first subcooling valve corresponding to the target pipe temperature in the previous cycle is used as the target opening. This can maintain exhaust stability and maximize the amount of refrigerant in the main circuit of the multi-split system, thereby improving the operating efficiency of the multi-split system.

[0053] Example 2

[0054] Based on the above method embodiments, this invention provides another subcooling valve control method applied to a multi-split air conditioning system; wherein, the multi-split air conditioning system includes multiple outdoor units and multiple indoor units, and the method focuses on describing the determination of different control modes of the subcooling valve and the process of determining the target opening degree in each control mode.

[0055] like Figure 2 As shown, the method includes the following steps:

[0056] Step S202: In the multi-split system, all outdoor units are fully turned on for cooling operation, and the system runs continuously for 10 minutes. For ease of explanation, we will take the subcooling valve of one outdoor unit as an example.

[0057] Step S204: Determine if Td≤A; that is, determine if the exhaust temperature of the compressor of the outdoor unit is not greater than the preset temperature threshold. If yes, proceed to step S206; if no, proceed to step S212. Wherein, Td is the exhaust temperature of the current cycle, and A represents the preset temperature threshold, which ranges from 100℃ to 110℃, preferably 105℃.

[0058] Step S206, first control mode; that is, controlling the subcooling valve according to the target subcooling degree;

[0059] Step S208: Determine if the following conditions are met for the previous three consecutive cycles: First cycle (i.e., the cycle two cycles prior to the previous one), indoor unit superheat = B and exhaust superheat > C, target pipe temperature Tem min The corresponding subcooling valve opening is P3; in the second cycle (i.e., the cycle before that), the indoor unit superheat = B and the exhaust superheat > C, and the target pipe temperature Tem min The corresponding subcooling valve opening is P2; in the third cycle (i.e., the previous cycle), the indoor unit superheat = B and the exhaust superheat > C, and the target pipe temperature Tem min The corresponding subcooling valve opening is P1; if so, proceed to step S210; otherwise, return to step S206 and continue to control the subcooling valve according to the first control method. That is, if the above conditions are not met in the three consecutive cycles before the current cycle, continue to control the subcooling valve according to the target subcooling degree until the above conditions are met in the three consecutive cycles before the current cycle.

[0060] Wherein, B represents the first superheat threshold, with a value range of -1℃ to 3℃, preferably 0℃; C represents the second superheat threshold, with a value range of 10℃ to 40℃, preferably 20℃;

[0061] Step S210, subsequent P(n) = Pa = (P1 + P2 + P3) / 3; that is, in the current cycle and subsequent cycles, the subcooling valve is controlled to operate at the target opening degree Pa and remain unchanged; where P represents the opening degree of the subcooling valve and n represents the current cycle;

[0062] Step S212, second control mode; that is, to force control of the subcooling valve according to the exhaust temperature;

[0063] Step S214: Determine whether the following conditions are met: Td(n) < Td(n-1), and the indoor unit superheat in the current cycle n = D and the exhaust superheat > C; if yes, proceed to step S216; otherwise, return to step S212 and continue to forcibly control the subcooling valve according to the second control method, that is, continue to adjust the opening of the subcooling valve according to the exhaust temperature; where D represents the third superheat threshold, the value range is -3℃ to 3℃, preferably 0℃;

[0064] Step S216, subsequent P(n) = Pb, where Pb is the target tube temperature Tem in the previous cycle. min The corresponding subcooling valve opening; thus, when the exhaust temperature decreases, to satisfy the indoor unit superheat and exhaust superheat, the subcooling valve opening remains at the subcooling valve opening corresponding to the target pipe temperature in the previous cycle, that is, the subcooling valve opening corresponding to the minimum pipe temperature.

[0065] To make it easier to understand, an example is given here. For instance, in a multi-split air conditioning system, after the outdoor unit has been running at full cooling capacity for 10 minutes, a certain subcooling valve changes periodically (180pls-240pls), corresponding to a compressor discharge temperature of 97℃-98℃.

[0066] In the three historical cycles preceding the current cycle, in the first historical cycle, the subcooling valve opening corresponding to the target pipe temperature was 200 pls, the indoor unit superheat was 1℃, the exhaust superheat was 20℃, and the target pipe temperature was 10℃. In the second historical cycle, the subcooling valve opening was 210 pls, the indoor unit superheat was 1℃, the exhaust superheat was 21℃, and the lowest indoor unit pipe temperature was 10.1℃. In the third historical cycle, the subcooling valve opening was 206 pls, the indoor unit superheat was 1℃, the exhaust superheat was 17℃, and the lowest indoor unit pipe temperature was 10.3℃. Therefore, the subcooling valve opening will be maintained at 205 pls thereafter.

[0067] Therefore, the above-mentioned subcooling valve control method intelligently controls the opening of the subcooling valve based on the subcooling valve opening, exhaust superheat, and indoor unit superheat, so that the exhaust of the multi-split system is stable and the output is maximized, thereby improving the operating effect of the multi-split system.

[0068] Example 3

[0069] This invention provides a multi-unit system, such as... Figure 3As shown, it includes, but is not limited to: compressor 301, gas-liquid separator 302, oil separator 303, four-way valve 304, outdoor heat exchanger 305, plate heat exchanger 306, electronic expansion valve 307, subcooling valve 308, liquid pipe shut-off valve 309, and gas pipe shut-off valve 310; the specific structural diagram of the multi-split system can be referred to the existing multi-split system, and the embodiments of the present invention will not be described in detail here.

[0070] Specifically, in cooling mode, the refrigerant condenses in the outdoor heat exchanger 305 and circulates in two main paths: one (main path) passes through the plate heat exchanger 306 to the liquid line shut-off valve 309 and the indoor unit (not shown); the other (auxiliary path) passes through the subcooling valve 308 to the gas-liquid separator 302. Therefore, the opening of the subcooling valve 308 controls both the subcooling degree (high-pressure temperature minus liquid line temperature) and the exhaust temperature. However, if the subcooling valve 308 opening is too large, there will be insufficient refrigerant in the main path, resulting in insufficient output capacity; if the subcooling valve 308 opening is too small, the subcooling degree will be insufficient, and the pressure loss problem in the long pipe will lead to low output from the indoor unit, and the exhaust temperature will also be too high. Therefore, controlling the opening of the subcooling valve 308 within a reasonable range can not only ensure stable exhaust but also ensure maximum output of the multi-split system.

[0071] When the exhaust temperature is relatively low, the subcooling valve 308 is controlled by the target subcooling degree to open or close. During this process, it is detected that the indoor unit superheat is in the best state when it is at a certain opening degree, the exhaust superheat meets the requirement of no liquid return, and the target pipe temperature is the lowest. This indicates that the multi-split system output is at its maximum at this time. Therefore, the opening degree of the subcooling valve 308 is maintained at the average opening degree Pa corresponding to the previous 3 consecutive cycles.

[0072] Conversely, when the temperature is relatively high, the subcooling valve 308 is forced to open wider under the control of the exhaust temperature to reduce the exhaust temperature. During this process, the indoor unit pipe temperature will gradually rise. As the subcooling valve opens wider, the exhaust temperature will gradually decrease. When the exhaust temperature decreases, it indicates that the opening of the subcooling valve 308 can maintain stable exhaust. At this point, by finding the condition that the indoor unit superheat and exhaust superheat meet the requirements of no drastic liquid return during the exhaust temperature decrease, the subcooling valve 308 maintains the opening Pb corresponding to the lowest indoor unit pipe temperature (i.e., the target pipe temperature) in the previous cycle. This maintains constant exhaust while maximizing the amount of refrigerant on the main line, thereby maintaining the lowest pipe temperature and increasing output, ensuring the operating effect of the multi-split system.

[0073] Example 4

[0074] Corresponding to the above method embodiments, this invention also provides a subcooling valve control device applied to a multi-split air conditioning system; wherein the multi-split air conditioning system includes multiple outdoor units and multiple indoor units; such as Figure 4As shown, the device includes: a parameter acquisition module 41, a first determination module 42, a second determination module 43, and a control operation module 44; wherein the functions of each module are as follows:

[0075] The parameter acquisition module 41 is used to periodically acquire operating parameters after all outdoor units have been running for a preset time. The operating parameters include: the superheat of the indoor unit corresponding to each operating indoor unit, the exhaust temperature and exhaust superheat of the compressor in each outdoor unit, and the opening degree of the subcooling valve corresponding to the target pipe temperature. The target pipe temperature is used to characterize the minimum pipe temperature of the middle pipe temperature of the indoor heat exchanger in the indoor unit.

[0076] The first determining module 42 is used to determine the control mode of the subcooling valve in the current cycle based on the exhaust temperature and the preset temperature threshold. The control mode includes a first control mode and a second control mode. The first control mode is used to characterize the way the subcooling valve is controlled according to the preset target subcooling degree, and the second control mode is used to characterize the way the subcooling valve is controlled according to the exhaust temperature.

[0077] The second determining module 43 is used to determine the target opening degree corresponding to the current cycle in the control mode based on the operating parameters and the preset superheat threshold.

[0078] The control operation module 44 is used to control the subcooling valve to operate at the target opening degree in the current cycle.

[0079] The subcooling valve control device provided in this embodiment of the invention determines different control modes of the subcooling valve according to the exhaust temperature. In the control mode, the opening of the subcooling valve is intelligently controlled according to the opening degree of the subcooling valve, the exhaust superheat degree, and the indoor unit superheat degree, so that the exhaust of the multi-split system is stable and the output is maximized, thereby improving the operating effect of the multi-split system.

[0080] Preferably, the first determining module 42 is further configured to: if the exhaust temperature is not greater than a preset temperature threshold, determine that the control mode of the subcooling valve corresponding to the compressor in the current cycle is the first control mode; or, if the exhaust temperature is greater than the preset temperature threshold, determine that the control mode of the subcooling valve corresponding to the compressor in the current cycle is the second control mode.

[0081] Preferably, the second determining module 43 is further configured to: if the control mode is the first control mode, obtain historical parameters prior to the current cycle; wherein the historical parameters include: the first historical parameter corresponding to the previous cycle, the second historical parameter corresponding to the cycle before that, and the third historical parameter corresponding to the cycle before that; and determine the target opening degree corresponding to the current cycle based on the historical parameters and the overheating threshold.

[0082] Preferably, the superheat thresholds include a first superheat threshold, a second superheat threshold, and a third superheat threshold; the first historical parameters include: the first indoor unit superheat, the first exhaust superheat, and the opening degree of the first subcooling valve corresponding to the target pipe temperature in the previous cycle; the second historical parameters include: the second indoor unit superheat, the second exhaust superheat, and the opening degree of the second subcooling valve corresponding to the target pipe temperature in the cycle two weeks prior; the third historical parameters include: the third indoor unit superheat, the third exhaust superheat, and the opening degree of the third subcooling valve corresponding to the target pipe temperature in the cycle two weeks prior; determining the target opening degree corresponding to the current cycle based on the historical parameters and the superheat thresholds includes: if the first indoor unit superheat, the second indoor unit superheat, and the third indoor unit superheat are all equal to the first superheat threshold, and the first exhaust superheat, the second exhaust superheat, and the third exhaust superheat are all greater than the second superheat threshold, the target opening degree corresponding to the current cycle is calculated based on the opening degrees of the first subcooling valve, the second subcooling valve, and the third subcooling valve.

[0083] Preferably, the above-mentioned calculation of the target opening degree corresponding to the current cycle based on the opening degree of the first subcooling valve, the opening degree of the second subcooling valve, and the opening degree of the third subcooling valve includes: the calculation formula of the target opening degree is as follows: Pa=(P1+P2+P3) / 3; where Pa represents the target opening degree, P1 represents the opening degree of the first subcooling valve, P2 represents the opening degree of the second subcooling valve, and P3 represents the opening degree of the third subcooling valve.

[0084] Preferably, the second determining module 43 is further configured to: when the control mode is the second control mode, if the exhaust temperature of the current cycle is less than the exhaust temperature of the previous cycle, and the superheat of the indoor unit in the current cycle is equal to the third superheat threshold, and the exhaust superheat of the current cycle is greater than the second superheat threshold, then the opening degree of the first subcooling valve corresponding to the target pipe temperature in the previous cycle is taken as the target opening degree corresponding to the current cycle.

[0085] Preferably, the parameter acquisition module 41 is further configured to: acquire the inlet temperature and outlet temperature of the indoor heat exchanger in each cycle, and calculate the indoor unit superheat based on the inlet temperature and outlet temperature; and acquire the saturation temperature corresponding to the high pressure in the outdoor unit, and calculate the exhaust superheat of the compressor in the outdoor unit based on the exhaust temperature and saturation temperature.

[0086] The subcooling valve control device provided in this embodiment of the invention has the same technical features as the subcooling valve control method provided in the above embodiments, so it can also solve the same technical problems and achieve the same technical effects.

[0087] This invention also provides a multi-unit air conditioning system, including a processor and a memory. The memory stores machine-executable instructions that can be executed by the processor, and the processor executes the machine-executable instructions to implement the above-described subcooling valve control method.

[0088] See Figure 5 As shown, the multi-unit system includes a processor 100 and a memory 101. The memory 101 stores machine-executable instructions that can be executed by the processor 100. The processor 100 executes the machine-executable instructions to implement the above-described subcooling valve control method.

[0089] Furthermore, Figure 5 The multi-unit system shown also includes a bus 102 and a communication interface 103. The processor 100, the communication interface 103 and the memory 101 are connected via the bus 102.

[0090] The memory 101 may include high-speed random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Communication between this system network element and at least one other network element is achieved through at least one communication interface 103 (which can be wired or wireless), such as the Internet, wide area network, local area network, or metropolitan area network. The bus 102 may be an ISA (Industrial Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Enhanced Industry Standard Architecture) bus. These buses can be categorized as address buses, data buses, and control buses. For ease of representation, Figure 5 The symbol is represented by a single double-headed arrow, but this does not mean that there is only one bus or one type of bus.

[0091] Processor 100 may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by the integrated logic circuitry in the hardware of processor 100 or by instructions in software form. Processor 100 may be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. The software module can reside in a readily available storage medium in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory 101, and the processor 100 reads the information from memory 101 and, in conjunction with its hardware, completes the steps of the method described in the foregoing embodiments.

[0092] This embodiment also provides a machine-readable storage medium storing machine-executable instructions. When the machine-executable instructions are called and executed by the processor, the machine-executable instructions cause the processor to implement the above-described supercooling valve control method.

[0093] The computer program product of the subcooling valve control method, device and multi-split system provided in the embodiments of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.

[0094] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0095] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0096] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0097] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0098] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A supercooling valve control method characterized by, The method is applied to a multi-connected system, wherein the multi-connected system comprises a plurality of outdoor units and a plurality of indoor units, and the method comprises the following steps: When all the outdoor units are refrigerated for a preset length of time, periodically obtain operating parameters, wherein the operating parameters comprise: an indoor unit overheat degree corresponding to each operating indoor unit, a discharge temperature of a compressor in each outdoor unit, a discharge overheat degree, and a supercooling valve opening degree corresponding to a target pipe temperature used to represent a minimum pipe temperature of a middle part of an indoor heat exchanger in the indoor unit; According to the discharge temperature and a preset temperature threshold, determine a control mode of the supercooling valve in a current period, wherein the control mode comprises a first control mode and a second control mode, the first control mode is used to represent a mode of controlling the supercooling valve according to a preset target supercooling degree, and the second control mode is used to represent a mode of controlling the supercooling valve according to the discharge temperature; In the control mode, determine a target opening degree corresponding to the current period according to the operating parameters and a preset overheat degree threshold, wherein if the control mode is the first control mode, obtain historical parameters before the current period, wherein the historical parameters comprise: a first historical parameter corresponding to a last period, a second historical parameter corresponding to a period before the last period, and a third historical parameter corresponding to a period before the period before the last period; the overheat degree threshold comprises a first overheat degree threshold, a second overheat degree threshold, and a third overheat degree threshold; the first historical parameter comprises: a first indoor unit overheat degree, a first discharge overheat degree, and a first supercooling valve opening degree corresponding to the target pipe temperature in the last period; the second historical parameter comprises: a second indoor unit overheat degree, a second discharge overheat degree, and a second supercooling valve opening degree corresponding to the target pipe temperature in the period before the last period; the third historical parameter comprises: a third indoor unit overheat degree, a third discharge overheat degree, and a third supercooling valve opening degree corresponding to the target pipe temperature in the period before the period before the last period; if the first indoor unit overheat degree, the second indoor unit overheat degree, and the third indoor unit overheat degree are all equal to the first overheat degree threshold, and the first discharge overheat degree, the second discharge overheat degree, and the third discharge overheat degree are all greater than the second overheat degree threshold, the target opening degree corresponding to the current period is calculated according to the first supercooling valve opening degree, the second supercooling valve opening degree, and the third supercooling valve opening degree; when the control mode is the second control mode, if the discharge temperature of the current period is less than the discharge temperature of the last period, and the indoor unit overheat degree of the current period is equal to the third overheat degree threshold, and the discharge overheat degree of the current period is greater than the second overheat degree threshold, the first supercooling valve opening degree corresponding to the target pipe temperature in the last period is taken as the target opening degree corresponding to the current period; Control the supercooling valve to operate according to the target opening degree in the current period.

2. The method of claim 1, wherein, The step of determining the control mode of the supercooling valve in the current period according to the discharge temperature and a preset temperature threshold comprises: If the exhaust temperature is not greater than the preset temperature threshold, it is determined that the control mode of the subcooling valve corresponding to the compressor in the current period is the first control mode; or if the exhaust temperature is greater than the preset temperature threshold, it is determined that the control mode of the subcooling valve corresponding to the compressor in the current period is the second control mode.

3. The method of claim 1, wherein, The step of calculating the target opening degree corresponding to the current period according to the first subcooling valve opening degree, the second subcooling valve opening degree and the third subcooling valve opening degree comprises: The calculation formula of the target opening degree is as follows: Pa=(P1+P2+P3) / 3 Wherein, Pa represents the target opening degree, P1 represents the first subcooling valve opening degree, P2 represents the second subcooling valve opening degree, and P3 represents the third subcooling valve opening degree.

4. The method of claim 1, wherein, The step of periodically acquiring operating parameters comprises: In each period, the inlet temperature and the outlet temperature of the indoor heat exchanger are acquired, and the indoor superheat degree of the indoor unit is calculated according to the inlet temperature and the outlet temperature; and the saturation temperature corresponding to the high-pressure pressure in the outdoor unit is acquired, and the exhaust superheat degree of the compressor in the outdoor unit is calculated according to the exhaust temperature and the saturation temperature.

5. A supercooling valve control device characterized by comprising: The application is applied to a multi-split system; wherein, the multi-split system comprises a plurality of outdoor units and a plurality of indoor units; the device comprises: A parameter acquisition module is configured to periodically acquire operating parameters after all the outdoor units have been operated for a preset length of time; wherein, the operating parameters comprise: the indoor superheat degree corresponding to each operating indoor unit, the exhaust temperature and the exhaust superheat degree of the compressor in each outdoor unit, and the subcooling valve opening degree corresponding to the target pipe temperature, which is used to represent the minimum pipe temperature of the middle pipe temperature of the indoor heat exchanger in the indoor unit; A first determination module is configured to determine the control mode of the subcooling valve in the current period according to the exhaust temperature and a preset temperature threshold; wherein, the control mode comprises a first control mode and a second control mode, the first control mode is used to represent the mode of controlling the subcooling valve according to a preset target subcooling degree, and the second control mode is used to represent the mode of controlling the subcooling valve according to the exhaust temperature. The second determining module is configured to determine the target opening degree corresponding to the current period according to the operating parameter and a preset superheat threshold in the control mode; wherein, if the control mode is the first control mode, a historical parameter before the current period is obtained; wherein, the historical parameter comprises a first historical parameter corresponding to a last period, a second historical parameter corresponding to a period before the last period, and a third historical parameter corresponding to a period before the period before the last period; the superheat threshold comprises a first superheat threshold, a second superheat threshold, and a third superheat threshold; the first historical parameter comprises a first indoor superheat, a first exhaust superheat, and a first subcooling valve opening degree corresponding to the target pipe temperature in the last period; the second historical parameter comprises a second indoor superheat, a second exhaust superheat, and a second subcooling valve opening degree corresponding to the target pipe temperature in the period before the last period; the third historical parameter comprises a third indoor superheat, a third exhaust superheat, and a third subcooling valve opening degree corresponding to the target pipe temperature in the period before the period before the last period; if the first indoor superheat, the second indoor superheat, and the third indoor superheat are all equal to the first superheat threshold, and the first exhaust superheat, the second exhaust superheat, and the third exhaust superheat are all greater than the second superheat threshold, the target opening degree corresponding to the current period is calculated according to the first subcooling valve opening degree, the second subcooling valve opening degree, and the third subcooling valve opening degree; when the control mode is the second control mode, if the exhaust temperature of the current period is less than the exhaust temperature of the last period, and the indoor superheat of the current period is equal to the third superheat threshold, and the exhaust superheat of the current period is greater than the second superheat threshold, the first subcooling valve opening degree corresponding to the target pipe temperature in the last period is taken as the target opening degree corresponding to the current period. The control operating module is configured to control the subcooling valve to operate according to the target opening degree in the current period.

6. A multi-split system comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein, The processor executes the computer program to implement the steps of the method of any one of claims 1-4.

7. A computer readable storage medium characterized in that, The computer readable storage medium stores the computer program, and the computer program is executed by the processor to implement the steps of the method of any one of claims 1-4.

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