CN113959054B - Control method for preventing overheating of multi-split evaporator and multi-split air conditioner - Google Patents
Control method for preventing overheating of multi-split evaporator and multi-split air conditioner Download PDFInfo
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- CN113959054B CN113959054B CN202111189338.2A CN202111189338A CN113959054B CN 113959054 B CN113959054 B CN 113959054B CN 202111189338 A CN202111189338 A CN 202111189338A CN 113959054 B CN113959054 B CN 113959054B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/50—Control or safety arrangements characterised by user interfaces or communication
- F24F11/61—Control or safety arrangements characterised by user interfaces or communication using timers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/89—Arrangement or mounting of control or safety devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
- F24F3/06—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units
- F24F3/065—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units with a plurality of evaporators or condensers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F2140/00—Control inputs relating to system states
- F24F2140/20—Heat-exchange fluid temperature
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Abstract
The invention discloses a control method for preventing an evaporator of a multi-split air conditioner from being overheated and the multi-split air conditioner. The control method comprises the following steps: s1, collecting the tube temperature of each evaporator and the corresponding air tube temperature and liquid tube temperature; determining a first overheating temperature of the evaporator according to the temperature of each evaporator tube and the corresponding temperature of the air tube and the liquid tube; s2, judging whether the first overheating temperature is lower than a program set overheating temperature or not, and executing a step S3 if the first overheating temperature of the evaporator is lower than the program set overheating temperature; if not, executing the step S4; s3, calculating a second superheat temperature of the evaporator according to the temperature of the evaporator tube at the current moment and the temperature of the air tube corresponding to the evaporator tube, and controlling the opening degree of an expansion valve corresponding to the evaporator to keep the second superheat temperature within a target superheat degree range; and S4, executing an expansion valve opening control process corresponding to the evaporator, and executing the step S2 again.
Description
Technical Field
The invention relates to the field of air conditioners, in particular to a control method for preventing an evaporator of a multi-split air conditioner from being overheated and the multi-split air conditioner.
Background
The prior multi-connected air conditioner outdoor unit is simultaneously connected with a plurality of indoor units, each indoor unit is provided with 1 electronic expansion valve for controlling flow, a connecting pipe air pipe and a connecting pipe liquid pipe of each indoor unit and the outdoor unit are connected with a temperature sensing bag, an indoor unit evaporator is also connected with a pipe temperature sensing bag, the refrigerant flow distributed to different indoor units by the prior air conditioner system is controlled by superheat degree, namely, the difference of the pipe temperature of the air pipe and the evaporator is judged, and the corresponding opening degree of the electronic expansion valve is adjusted. Because different indoor set evaporator tube temperature sensing package positions are different, the overheated condition has appeared in certain indoor set evaporimeter under some circumstances probably, the temperature of tube temperature sensing package department is also very high, but the refrigerant can appear the flash evaporation phenomenon after different flow paths gather, the temperature that leads to the trachea to detect is less than the evaporimeter tube temperature, control procedure can think the evaporimeter refrigerant evaporation incompletely by mistake, thereby control expansion valve aperture does not break off little, the phenomenon of reverse adjustment appears, further aggravate the overheated condition, lead to this indoor set refrigerant flow not enough, evaporimeter heat transfer area can not effectively be utilized, it is higher more to finally lead to this indoor set to compare the air-out temperature of other operation indoor sets, the refrigeration effect is poor, can lead to the condensation problem to take place because the evaporimeter import and export difference in temperature is big when serious. At this time, the evaporator can be controlled to prevent overheating by a new control method, thereby avoiding the above abnormal problems.
Disclosure of Invention
In view of the above, the present invention discloses a control method for preventing overheating of a multi-split air conditioner and a multi-split air conditioner, so as to at least solve the problem of overheating of an evaporator caused by uneven refrigerant flow distribution in the multi-split air conditioner.
In order to achieve the above object, the invention adopts the following technical scheme:
the invention discloses a control method for preventing overheating of a multi-split evaporator, wherein the multi-split evaporator comprises an air conditioner outdoor unit and a plurality of indoor units which are simultaneously connected with the air conditioner outdoor unit, the air conditioner outdoor unit comprises a compressor and an outdoor heat exchanger, each indoor unit is provided with an indoor heat exchanger and an expansion valve, an air pipe is connected between the indoor heat exchanger of each indoor unit and the compressor of the outdoor unit, and a liquid pipe is connected between the indoor heat exchanger of each indoor unit and the outdoor heat exchanger of the outdoor unit, the control method comprises the following steps:
s1, collecting the tube temperature of each evaporator and the corresponding air tube temperature and liquid tube temperature of the evaporator; determining a first overheating temperature of each evaporator according to the evaporator tube temperature and the corresponding air tube temperature and liquid tube temperature;
s2, judging whether the first overheat temperature of each evaporator is lower than a program set overheat temperature or not, and executing the step S3 if the first overheat temperature of each evaporator is lower than the program set overheat temperature; if not, executing the step S4;
s3, calculating a second superheat temperature of the evaporator according to the temperature of the evaporator pipe at the current moment and the temperature of the air pipe corresponding to the evaporator pipe, and controlling the opening of an expansion valve corresponding to the evaporator to keep the second superheat temperature within a target superheat degree range;
and S4, executing an expansion valve opening control process corresponding to the evaporator, and executing the step S2 again.
Further optionally, the step S1 includes:
detecting the temperature of an evaporator tube of the evaporator and the temperature of an air pipe and a liquid pipe corresponding to the evaporator;
calculating a first difference between the evaporator tube temperature and the liquid tube temperature, and calculating a second difference between the air tube temperature and the evaporator tube temperature;
determining a maximum of the first difference and the second difference as the first superheat temperature.
Further optionally, the calculating a second superheat temperature of the evaporator according to the evaporator tube temperature at the current time and the corresponding air tube temperature includes:
detecting the temperature of an evaporator tube at the current moment and the temperature of an air tube at the current moment;
and calculating the difference value between the air pipe temperature at the current moment and the evaporator pipe temperature at the current moment as the second overheating temperature.
Further optionally, the controlling the opening degree of an expansion valve corresponding to the evaporator to keep the second superheat temperature within a target superheat degree range includes:
judging whether the second superheat temperature is within the target superheat degree range or not;
when the second superheat temperature is larger than the maximum value in the target superheat degree range, judging that the refrigerant in the evaporator is evaporated and superheated, and controlling the opening of an expansion valve corresponding to the evaporator to be large;
when the second superheat temperature is lower than the minimum value in the target superheat degree range, judging that the refrigerant in the evaporator is incompletely evaporated, and controlling the expansion valve corresponding to the evaporator to be closed;
and when the second superheat temperature is in the target superheat degree range, controlling an expansion valve corresponding to the evaporator to maintain the current opening degree unchanged.
Further optionally, the step S4 further includes:
before executing the control process of opening and closing the expansion valve corresponding to the evaporator, executing the control process of preventing the expansion valve from closing.
Further optionally, the expansion valve closing prevention control process includes:
controlling the opening degree of an expansion valve corresponding to the evaporator to be not allowed to be reduced within a first preset time;
after the first preset time is reached, re-determining the first overheat temperature;
when the first overheat temperature obtained by redetermination is larger than or equal to the program set overheat temperature, executing an expansion valve opening control process corresponding to the evaporator; when the newly determined first overheat temperature < the program-set overheat temperature, step S3 is executed.
Further optionally, the expansion valve opening degree opening control process corresponding to the evaporator includes:
s41, controlling the opening of an expansion valve corresponding to the evaporator to be larger by a preset step number;
s42, re-determining the first overheating temperature after the second preset time is reached;
s43, when the first overheating temperature obtained through redetermination is less than the program set overheating temperature, executing the step S3; when it is newly determined that the obtained first superheat temperature is equal to or greater than the programmed superheat temperature, step S41 is executed.
Further optionally, the control method further includes: before executing step S1, executing step S0; wherein the step S0 includes:
the multi-split air conditioner enters a refrigeration mode;
controlling the opening degree of an expansion valve corresponding to each evaporator in the multi-split air conditioner to be opened according to the initial opening degree;
and after a third preset time, adjusting the exhaust temperature of each compressor in the multi-split air conditioner to be within a target exhaust temperature range.
The invention discloses a multi-split air conditioner in a second aspect, wherein the multi-split air conditioner adopts any one of the control methods.
Further optionally, the multi-split air conditioner includes: the system comprises a compressor, an outdoor heat exchanger, a plurality of indoor heat exchangers and a plurality of expansion valves, wherein the compressor, the outdoor heat exchanger, the plurality of indoor heat exchangers arranged in parallel and the plurality of expansion valves are sequentially connected to form a refrigerant circulation loop; and a temperature monitoring device;
the outdoor heat exchanger is connected with the indoor heat exchangers through a first refrigerant pipeline and a second refrigerant pipeline respectively, wherein the first refrigerant pipeline comprises: the outdoor heat exchanger comprises a first main line and a plurality of first parallel branches, wherein a first end of the first main line is connected with the outdoor heat exchanger, a second end of the first main line is connected with first ends of the plurality of first parallel branches, and second ends of the plurality of first parallel branches are connected with the plurality of indoor heat exchangers in a one-to-one correspondence manner; the second refrigerant line includes: the first end of the second main line is connected with the outdoor heat exchangers, the second end of the first main line is connected with the first ends of the second parallel branches, and the second ends of the second parallel branches are connected with the indoor heat exchangers in a one-to-one correspondence manner;
the compressor is arranged on the second trunk;
the expansion valves are correspondingly arranged on the first parallel branches one by one;
the temperature monitoring device includes: the liquid pipe temperature detection assembly is arranged on a liquid pipe section formed by the plurality of first parallel branches, the gas pipe temperature detection assembly is arranged on a gas pipe section formed by the plurality of second parallel branches, and the heat exchanger temperature detection assembly is used for detecting the plurality of indoor heat exchangers;
wherein when the multi-split air conditioner is in refrigeration operation, the plurality of indoor heat exchangers serve as the evaporator.
Has the beneficial effects that: according to the invention, after the multi-split air conditioner is improved, the refrigerant distribution uniformity when the free distribution air conditioner is connected with a plurality of indoor units is improved, and the problems of overheating of the indoor units and poor refrigeration effect or condensation caused by overheating of the indoor units are avoided.
Drawings
The above and other objects, features and advantages of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings. The drawings described below are merely exemplary embodiments of the present disclosure, and other drawings may be derived by those skilled in the art without inventive effort.
Fig. 1 illustrates an overheating prevention control flowchart of a multi-split air conditioner according to an embodiment;
fig. 2 illustrates an overheating prevention control logic diagram of a multi-split air conditioner according to an embodiment;
fig. 3 shows a schematic diagram of a multi-split air conditioning system according to an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, and "a" and "an" generally include at least two, but do not exclude at least one, unless the context clearly dictates otherwise.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or system. Without further limitation, an element defined by the phrases "comprising one of \8230;" does not exclude the presence of additional like elements in an article or system comprising the element.
The current multi-split air conditioner can lead to the overheating problem of the indoor unit due to uneven flow distribution. Compared with the traditional flow distribution control method of the multi-connected air conditioner, the novel anti-overheating control method provided by the invention has the advantages that the evaporator anti-overheating temperature parameter is newly introduced and is used as a key parameter for controlling the anti-overheating of the multi-connected air conditioner evaporator. When the parameter value is detected to exceed the preset parameter of the system, the corresponding evaporator of the indoor unit is considered to be seriously overheated, the corresponding expansion valve needs to be controlled to be opened and closed, and the flow of the refrigerant in the indoor unit is increased.
To further illustrate the technical solution of the present invention, the following specific examples are provided as shown in fig. 1 to 3.
Example 1
As shown in fig. 1, in the present embodiment, there is provided an overheat prevention control method for an evaporator in a multi-split air conditioner indoor unit, the control method including:
s1, collecting the tube temperature of each evaporator and the temperature of an air tube and a liquid tube which are correspondingly connected with the tube temperature; determining a first overheating temperature of the evaporator according to the temperature of each evaporator tube and the corresponding temperature of the air tube and the liquid tube;
s2, judging whether the first overheating temperature is lower than a program set overheating temperature or not, and if the first overheating temperature of the evaporator is judged to be lower than the program set overheating temperature, executing the step S3 aiming at the indoor unit corresponding to the corresponding evaporator; if not, executing the step S4;
s3, calculating a second superheat temperature of the evaporator according to the temperature of the evaporator pipe at the current moment and the temperature of the air pipe corresponding to the evaporator pipe, and controlling the opening of an expansion valve corresponding to the evaporator to keep the second superheat temperature within a target superheat degree range;
and S4, executing an expansion valve opening degree opening control process corresponding to the evaporator, and executing the step S2 again.
The multi-connected air conditioner is connected with a plurality of indoor units, and when the indoor units work simultaneously, the multi-connected air conditioner relates to the distribution of refrigerant among different indoor units. In this embodiment, the outdoor unit controller judges the overheating condition of the evaporator by detecting the temperatures of the tubes of the evaporators of different indoor units and the temperatures of the corresponding connecting tubes and liquid tubes, and if the evaporator is judged to be overheated, the evaporator is opened by controlling the opening of the corresponding electronic expansion valve, so that the serious overheating condition of the evaporator is avoided.
In some optional manners, the control method further comprises: step S0 is performed before step S1 is performed. The step S0 includes: the multi-split air conditioner enters a refrigeration mode; controlling the opening of an expansion valve corresponding to each evaporator in the multi-split air conditioner to be opened according to the initial opening; and after a third preset time, adjusting the exhaust temperature of each compressor in the multi-split air conditioner to be within a target exhaust temperature range. Specifically, when the multi-connected air conditioner is connected with a plurality of indoor units for refrigerating operation, the expansion valves corresponding to the indoor units are controlled to be opened according to the initial opening degree of the air conditioner, and after the operation time reaches the operation time of the initial opening degree of the electronic expansion valves corresponding to the indoor units, which is set by the outdoor unit controller, the operation enters a target exhaust control stage, namely the opening degrees of the electronic expansion valves of the operating indoor units are controlled to be increased or decreased at the same time, so that the target exhaust value set by a program is reached; and when the target exhaust range is reached, entering a flow distribution stage of each running indoor unit, controlling according to the target superheat degree of each indoor unit, and simultaneously adding an evaporator anti-overheating control process, wherein the anti-overheating control process is the process from the step S1 to the step S4.
In this embodiment, the step S1 includes: detecting the temperature of an evaporator tube of the evaporator and the temperature of an air pipe and a liquid pipe corresponding to the evaporator; calculating a first difference between the evaporator tube temperature and the liquid tube temperature, and calculating a second difference between the air tube temperature and the evaporator tube temperature; determining a maximum of the first difference and the second difference as the first superheat temperature. The calculating the second superheat temperature of the evaporator according to the evaporator tube temperature at the current moment and the corresponding air tube temperature comprises: detecting the temperature of an evaporator tube at the current moment and the temperature of an air tube at the current moment; and calculating the difference value between the air pipe temperature at the current moment and the evaporator pipe temperature at the current moment as the second overheating temperature.
In this embodiment, the controlling the opening degree of the expansion valve corresponding to the evaporator to keep the second superheat temperature within the target superheat degree range includes: judging whether the second superheat temperature is within the target superheat degree range or not; when the second superheat temperature is larger than the maximum value in the target superheat degree range, judging that the refrigerant in the evaporator is evaporated and superheated, and controlling an expansion valve corresponding to the evaporator to be opened greatly; when the second superheat temperature is lower than the minimum value in the target superheat degree range, judging that the refrigerant in the evaporator is incompletely evaporated, and controlling an expansion valve corresponding to the evaporator to be closed; and when the second superheat temperature is in the target superheat degree range, controlling an expansion valve corresponding to the evaporator to maintain the current opening degree unchanged.
In some optional manners, the step S4 further includes: before executing the control process of opening and closing the expansion valve corresponding to the evaporator, executing the control process of preventing the expansion valve from closing. Specifically, the expansion valve closing prevention control process includes: controlling the opening degree of an expansion valve corresponding to the evaporator to be not allowed to be reduced within a first preset time; after the first preset time is reached, re-determining the first overheating temperature; when the first overheating temperature obtained through redetermination is larger than or equal to the program set overheating temperature, executing an expansion valve opening degree opening control process corresponding to the evaporator; when the first superheat temperature obtained by the redetermination < the program set superheat temperature, step S3 is executed.
Preferably, the expansion valve opening degree opening control process for the evaporator includes:
s41, controlling the opening of an expansion valve corresponding to the evaporator to be larger by a preset step number;
s42, re-determining the first overheating temperature after the second preset time is reached;
s43, when the first overheating temperature obtained through redetermination is less than the program set overheating temperature, executing the step S3; when it is newly determined that the obtained first superheat temperature is equal to or greater than the programmed superheat temperature, step S41 is executed.
Example 2
As shown in fig. 2 to 3, in the present embodiment, there is provided a multi-split air conditioner that employs any one of the control methods of embodiment 1. The multi-split air conditioner includes: the system comprises a compressor, an outdoor heat exchanger, a plurality of indoor heat exchangers and a plurality of expansion valves, wherein the compressor, the outdoor heat exchanger, the plurality of indoor heat exchangers arranged in parallel and the plurality of expansion valves are sequentially connected to form a refrigerant circulation loop; and a temperature monitoring device.
The outdoor heat exchanger is connected with the plurality of indoor heat exchangers through a first refrigerant pipeline and a second refrigerant pipeline respectively, wherein the first refrigerant pipeline comprises: the outdoor heat exchanger comprises a first main line and a plurality of first parallel branches, wherein a first end of the first main line is connected with the outdoor heat exchanger, a second end of the first main line is connected with first ends of the plurality of first parallel branches, and second ends of the plurality of first parallel branches are connected with the plurality of indoor heat exchangers in a one-to-one correspondence manner; the second refrigerant line includes: the first end of the second main line is connected with the outdoor heat exchanger, the second end of the first main line is connected with the first ends of the second parallel branches, and the second ends of the second parallel branches are connected with the indoor heat exchangers in a one-to-one correspondence manner;
the compressor is arranged on the second trunk;
the expansion valves are correspondingly arranged on the first parallel branches one by one;
the temperature monitoring device includes: the liquid pipe temperature detection assembly is arranged on a liquid pipe section formed by the plurality of first parallel branches, the gas pipe temperature detection assembly is arranged on a gas pipe section formed by the plurality of second parallel branches, and the heat exchanger temperature detection assembly is used for detecting the plurality of indoor heat exchangers;
wherein when the multi-split air conditioner is in refrigeration operation, the plurality of indoor heat exchangers serve as the evaporator.
Based on the system of the multi-split air conditioner, when the multi-split air conditioner is used for refrigerating, the evaporator overheating prevention processing logic is as follows:
the multi-connected outdoor unit is simultaneously connected with a plurality of indoor units to operate in a refrigeration and dehumidification mode, and the operation of starting up the indoor unit is set according to a program to reach M Initial opening degree operation time And (namely, the third preset time) entering a target exhaust control stage, and judging whether the evaporator is overheated or not after target exhaust is achieved. Introducing an evaporator overheating judgment parameter: t is a unit of The superheat temperature of the evaporator is set to be, this judgment value is set to be the same for each evaporator:
T evaporator superheat temperature ＝Max(T Evaporator tube temperature -T Temperature of liquid pipe ，T Trachea temperature -T Temperature of liquid pipe )
During refrigerating operation, if the evaporator is in an overheat state, the liquid pipe temperature T Temperature of liquid pipe Will be at a temperature T higher than that of the trachea Trachea temperature Or the temperature T of the tube temperature sensing bulb of the evaporator is detected Evaporator tube temperature Wherein 1 temperature is low, through judging the difference that evaporimeter temperature sensing package detected temperature and liquid pipe temperature, and judge the difference of trachea temperature and liquid pipe temperature, judges the evaporimeter overheat condition that this indoor set corresponds according to the great value of two above differences, can effectively avoid control procedure misjudge the problem of the evaporimeter overheat condition.
Program setting a judgment value T Set the evaporator superheat temperature When T is calculated in real time Evaporator superheat temperature The judgment value T is more than or equal to the program setting Evaporator superheat temperature When the refrigerant flowing through the evaporator is insufficient, the evaporator is overheated, the opening degree of the electronic expansion valve corresponding to the indoor unit is controlled not to be allowed to be reduced, the flow of the refrigerant flowing through the evaporator cannot be reduced, and the overheating condition is avoided to be aggravated; continue to detect N 1 (i.e., first predetermined time) minutes later, if T is calculated in real time Evaporator superheat temperature A judgment value T set by a program is larger than or equal to Set the overheat temperature of the evaporator When the evaporator is used, the opening of the electronic expansion valve corresponding to the indoor unit is controlled to be increased by M steps, so that the flow of the refrigerant flowing through the evaporator is increased, and the overheating condition is solved; with N 2 min (i.e. the second predetermined time) is the detection period, every N 2 Detecting and judging once after minutes, if T is calculated in real time Evaporator superheat temperature The judgment value T is more than or equal to the program setting Set the evaporator superheat temperature Then controlling the opening of the electronic expansion valve corresponding to the indoor unit to continue to open for M steps until the T calculated in real time Evaporator superheat temperature < determination value of program setting T The superheat temperature of the evaporator is set, and the superheat temperature of the evaporator is set, the electronic expansion valve is controlled to enter the above target superheat degree control. For the condition that the multi-connected outdoor unit is simultaneously connected with a plurality of indoor units to operate in a refrigeration and dehumidification mode, the program can simultaneously detect or sequentially detect the real-time T of each evaporator Temperature of liquid pipe 、T The tube temperature of the evaporator, T Trachea temperature By simultaneous or sequential calculation of T Evaporator superheat temperature Setting T simultaneously or sequentially with the program Set the overheat temperature of the evaporator Judging, and finally calculating the superheat degree T of all evaporators in real time Evaporator superheat temperature Are all less than the target value T set by the program Set the evaporator superheat temperature I.e. until all evaporators reach the programmed non-overheating state. In addition, N is 1 And N 2 The same duration may be used, i.e., the first preset time is the same as the second preset time, and both of them may be set to be N minutes.
The above program sets T The superheat temperature of the evaporator is set, The N minutes and the M steps can be set by a program.
Preferably, T Set the evaporator superheat temperature The set range is 2-5 ℃, which can ensure the reasonable degree of superheat of air suction of the system, prevent the liquid from being carried by the air suction of the compressor, and prevent the abnormal phenomena of condensation, freezing and the like caused by the overheat of the evaporator.
Preferably, the setting range of the N minutes is 2 minutes to 10 minutes, the opening of the expansion valve can be timely adjusted, meanwhile, different system adjusting time and adjusting speed are different, and different time can be set according to different systems.
Preferably, the setting range of the M steps is 4 steps to 10 steps, so that the opening degree of the expansion valve can be effectively adjusted, different systems correspond to expansion valves with different specifications, different adjustment steps can be set according to different specifications of the expansion valve, the adjustment steps can be selected to be small when the aperture of the expansion valve is small, and the adjustment steps can be selected to be large when the aperture of the expansion valve is large.
Through the control, the situation that the multi-flow path evaporator is in an overheated state originally but the outlet temperature (air pipe temperature) of the multi-flow path refrigerant after gathering and flashing is low, namely T Trachea temperature Lower than T Evaporator tube temperature Causing the program to judge the refrigerating target superheat degree delta T = T Trachea temperature -T Evaporator tube temperature If the temperature is lower than the target delta T set by the program, the evaporator is not completely evaporated, so that the problem that the overheating state of the evaporator is judged by mistake by the program occurs.
The multiple indoor units simultaneously operate the target superheat degree control logic:
superheat degree Δ T = T of refrigeration evaporator Trachea temperature -T Evaporator tube temperature ；
Wherein the target Δ T: program set points, preferred ranges: the temperature is 3-8 ℃, the refrigerant can be fully evaporated in the evaporator by setting a reasonable target superheat degree, a certain suction superheat degree is ensured, and abnormal problems such as liquid impact of a compressor and the like are avoided; the target Δ T of each evaporator may be set to be the same or different;
T anti-fluctuation temperature range: program set points, preferred ranges: the temperature is 1-3 ℃, and the opening of the expansion valve is prevented from changing constantly by setting a reasonable fluctuation-preventing temperature range, so that the expansion valve can stably operate in a smaller range; target T for each evaporator Anti-fluctuation temperature range Can be set to be the same or different;
the evaporator of each indoor unit corresponds to the air pipe temperature and the evaporator pipe temperature, and when the outdoor unit and the indoor units run simultaneously to reach a stable state, namely reach the target exhaust temperature set by a program, the flow distribution stage of each running indoor unit is started. At the moment, the evaporator of each indoor unit respectively detects the corresponding delta T in real time and sets the target delta T and T with the program Anti-surge temperature range And comparing, judging the evaporation state of the refrigerant in the indoor unit, and controlling the corresponding electronic expansion valve to perform corresponding treatment.
Real-time detection of DeltaT > target DeltaT + T Anti-fluctuation temperature range Judging that the evaporator exceeds a target superheat degree, judging that the refrigerant in the indoor unit is overheated due to evaporation and insufficient refrigerant flow paths, and controlling a corresponding electronic expansion valve to be opened and closed; target Δ T-T Anti-surge temperature range Not more than real-time detection of not less than delta T and not more than target delta T + T The temperature range of the anti-fluctuation device, and judging that the evaporator reaches a target superheat degree range, and maintaining the opening degree of the electronic expansion valve at the current opening degree. Real-time detection of Delta T < target Delta T-T The temperature range of the anti-fluctuation device, and judging that the evaporator cannot reach the target superheat degree, judging that the refrigerant in the evaporator is incompletely evaporated, and controlling the corresponding electronic expansion valve to reduce.
Exemplary embodiments of the present disclosure are specifically illustrated and described above. It is to be understood that the present disclosure is not limited to the precise arrangements, instrumentalities, or instrumentalities described herein; on the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (8)
1. A control method for preventing overheating of a multi-split evaporator, wherein the multi-split evaporator comprises an air-conditioning outdoor unit and a plurality of indoor units which are simultaneously connected with the air-conditioning outdoor unit, the air-conditioning outdoor unit comprises a compressor and an outdoor heat exchanger, each indoor unit is provided with an indoor heat exchanger and an expansion valve, an air pipe is connected between the indoor heat exchanger of each indoor unit and the compressor of the outdoor unit, a liquid pipe is connected between the indoor heat exchanger of each indoor unit and the outdoor heat exchanger of the outdoor unit, and the indoor heat exchanger is used as the evaporator during cooling operation of the multi-split evaporator, and the control method comprises the following steps:
s1, collecting the tube temperature of each evaporator and the corresponding air tube temperature and liquid tube temperature; determining a first superheat temperature of each evaporator according to the temperature of each evaporator tube and the temperature of the corresponding air tube and liquid tube;
s2, judging whether the first overheating temperature of each evaporator is smaller than a program set overheating temperature or not, and executing the step S3 if the first overheating temperature of each evaporator is smaller than the program set overheating temperature; if not, executing the step S4;
s3, calculating a second superheat temperature of the evaporator according to the temperature of the evaporator pipe at the current moment and the temperature of the air pipe corresponding to the evaporator pipe, and controlling the opening of an expansion valve corresponding to the evaporator to keep the second superheat temperature within a target superheat degree range;
s4, executing an expansion valve opening degree opening control process corresponding to the evaporator, and re-executing the step S2;
wherein:
s1, determining a first superheat temperature of each evaporator according to the temperature of each evaporator tube and the temperature of the corresponding air tube and liquid tube comprises the following steps:
detecting the temperature of an evaporator tube of the evaporator and the temperature of an air pipe and a liquid pipe corresponding to the evaporator;
calculating a first difference between the evaporator tube temperature and the liquid tube temperature, and calculating a second difference between the air tube temperature and the evaporator tube temperature;
determining a maximum of the first difference and the second difference as the first superheat temperature;
s3, calculating a second overheating temperature of the evaporator according to the temperature of the evaporator tube at the current moment and the temperature of the air tube corresponding to the evaporator tube at the current moment comprises the following steps:
detecting the temperature of an evaporator tube at the current moment and the temperature of an air tube at the current moment;
and calculating the difference value between the air pipe temperature at the current moment and the evaporator pipe temperature at the current moment as the second overheating temperature.
2. The control method according to claim 1, wherein said controlling the opening degree of an expansion valve corresponding to the evaporator to maintain the second superheat temperature within a target superheat degree range comprises:
judging whether the second superheat temperature is within the target superheat degree range or not;
when the second superheat temperature is larger than the maximum value in the target superheat degree range, judging that the refrigerant in the evaporator is evaporated and superheated, and controlling the opening of an expansion valve corresponding to the evaporator to be large;
when the second superheat temperature is lower than the minimum value in the target superheat degree range, judging that the refrigerant in the evaporator is incompletely evaporated, and controlling the expansion valve corresponding to the evaporator to be closed;
and when the second superheat temperature is in the target superheat degree range, controlling an expansion valve corresponding to the evaporator to maintain the current opening degree unchanged.
3. The control method according to claim 1, wherein the step S4 further includes:
before executing the control process of opening and closing the expansion valve corresponding to the evaporator, executing the control process of preventing the expansion valve from closing.
4. The control method according to claim 3, wherein the expansion valve closing prevention control process includes:
controlling the opening degree of an expansion valve corresponding to the evaporator to be not allowed to be reduced within a first preset time;
after the first preset time is reached, re-determining the first overheat temperature;
when the first overheat temperature obtained by redetermination is larger than or equal to the program set overheat temperature, executing an expansion valve opening control process corresponding to the evaporator; when the newly determined first overheat temperature < the program-set overheat temperature, step S3 is executed.
5. The control method according to claim 1, wherein the expansion valve opening degree increase control process for the evaporator includes:
s41, controlling the opening of an expansion valve corresponding to the evaporator to be larger by a preset step number;
s42, re-determining the first overheating temperature after the second preset time is reached;
s43, when the first overheating temperature obtained through redetermination is smaller than the program set overheating temperature, executing a step S3; when the newly determined first overheat temperature is equal to or higher than the programmed overheat temperature, step S41 is executed.
6. The control method according to any one of claims 1 to 5, characterized by further comprising: before executing step S1, executing step S0; wherein the step S0 includes:
the multi-split air conditioner enters a refrigeration mode;
controlling the opening degree of an expansion valve corresponding to each evaporator in the multi-split air conditioner to be opened according to the initial opening degree;
and after a third preset time, adjusting the exhaust temperature of each compressor in the multi-split air conditioner to be within a target exhaust temperature range.
7. A multi-split air conditioner characterized in that the multi-split air conditioner employs the control method of any one of claims 1 to 6.
8. The multi-split air conditioner as recited in claim 7, wherein the multi-split air conditioner comprises: the system comprises a compressor, an outdoor heat exchanger, a plurality of indoor heat exchangers and a plurality of expansion valves, wherein the compressor, the outdoor heat exchanger, the plurality of indoor heat exchangers arranged in parallel and the plurality of expansion valves are sequentially connected to form a refrigerant circulation loop; and a temperature monitoring device;
the outdoor heat exchanger is connected with the plurality of indoor heat exchangers through a first refrigerant pipeline and a second refrigerant pipeline respectively, wherein the first refrigerant pipeline comprises: the outdoor heat exchanger comprises a first main line and a plurality of first parallel branches, wherein a first end of the first main line is connected with the outdoor heat exchanger, a second end of the first main line is connected with a first end of the plurality of first parallel branches, and second ends of the plurality of first parallel branches are connected with the plurality of indoor heat exchangers in a one-to-one correspondence manner; the second refrigerant line includes: the first end of the second main line is connected with the outdoor heat exchanger, the second end of the first main line is connected with the first ends of the second parallel branches, and the second ends of the second parallel branches are connected with the indoor heat exchangers in a one-to-one correspondence manner;
the compressor is arranged on the second trunk;
the expansion valves are correspondingly arranged on the first parallel branches one by one;
the temperature monitoring device includes: the liquid pipe temperature detection assembly is arranged on a liquid pipe section formed by the plurality of first parallel branches, the gas pipe temperature detection assembly is arranged on a gas pipe section formed by the plurality of second parallel branches, and the heat exchanger temperature detection assembly is used for detecting the plurality of indoor heat exchangers;
when the multi-split air conditioner is in refrigerating operation, the indoor heat exchangers are used as the evaporators.
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