CN111023435B - Control method and system for expansion valve of air conditioner and air conditioner - Google Patents

Control method and system for expansion valve of air conditioner and air conditioner Download PDF

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CN111023435B
CN111023435B CN201911395784.1A CN201911395784A CN111023435B CN 111023435 B CN111023435 B CN 111023435B CN 201911395784 A CN201911395784 A CN 201911395784A CN 111023435 B CN111023435 B CN 111023435B
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air conditioner
expansion valve
sub
evaporator
temperature
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CN111023435A (en
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林丽丹
刘方叶
林永河
温得贤
童炜
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TCL Air Conditioner Zhongshan Co Ltd
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TCL Air Conditioner Zhongshan Co Ltd
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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
    • F24F11/32—Responding to malfunctions or emergencies
    • F24F11/33—Responding to malfunctions or emergencies to fire, excessive heat or smoke
    • 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
    • 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
    • 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
    • F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
    • F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
    • F24F11/84—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using valves
    • 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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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Fuzzy Systems (AREA)
  • Mathematical Physics (AREA)
  • Human Computer Interaction (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

The invention discloses a control method and a control system for an expansion valve of an air conditioner and the air conditioner, wherein the control method comprises the following steps: acquiring the suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner; obtaining a target suction superheat degree according to the exhaust superheat degree; and adjusting the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree. The air conditioner obtains the suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner, obtains the target suction superheat degree according to the exhaust superheat degree, adjusts the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree, eliminates the deviation of a detection value and an actual value brought by a temperature sensing bulb by introducing the target suction superheat degree, and ensures the normal operation of the air conditioner.

Description

Control method and system for expansion valve of air conditioner and air conditioner
Technical Field
The invention relates to the technical field of air conditioners, in particular to a control method and a control system for an expansion valve of an air conditioner and the air conditioner.
Background
With the increasing standard of living, the air conditioner is used more and more widely in the family. With the technology of electronic expansion valves becoming more mature, more and more refrigeration equipment manufacturers adopt electronic expansion valves to accurately control the flow of refrigerant. The expansion valve is one of the key components of the refrigeration system, and the control quality of the opening degree of the expansion valve is the key for determining the quality of the refrigeration performance, so that the stability, the safety and the economy of the operation of the whole refrigeration system are greatly influenced.
In the existing expansion valve control method, the control of suction superheat degree is mostly adopted, and partial exhaust superheat degree is combined as auxiliary regulation. The air suction superheat degree has certain limitation at low-temperature environment temperature, and the deviation between the air suction superheat degree detected by the temperature sensing bulb and an actual value is large, so that the normal operation of the air conditioner is influenced.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
The invention aims to provide a control method and a control system for an expansion valve of an air conditioner and the air conditioner, so as to ensure that the air conditioner operates normally due to small deviation between the suction superheat degree and an actual value.
The technical scheme adopted by the invention for solving the technical problem is as follows:
in a first aspect, an embodiment of the present invention provides a control method for an expansion valve of an air conditioner, where the control method includes the following steps:
acquiring the suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner;
obtaining a target suction superheat degree according to the exhaust superheat degree;
and adjusting the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree.
As a further improved technical solution, the acquiring of the suction superheat and the discharge superheat of the compressor of the air conditioner includes:
obtaining the suction superheat degree according to the outlet temperature of an evaporator of the air conditioner and the suction temperature of a compressor of the air conditioner;
and obtaining the exhaust superheat degree according to the exhaust temperature of the compressor and the temperature of a condenser of the air conditioner.
As a further improvement, the adjusting the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree comprises:
obtaining a first opening variation of the expansion valve according to the suction superheat degree and the target suction superheat degree;
and adjusting the opening degree of an expansion valve of the air conditioner according to the first opening degree variable quantity of the expansion valve at intervals of preset time.
As a further improved technical scheme, the evaporator comprises at least 2 sub-evaporators; the expansion valve comprises at least 2 sub-expansion valves, and the sub-expansion valves are arranged in one-to-one correspondence with the sub-evaporators;
the operation state of the evaporator of the air conditioner includes the number of the sub-evaporators in operation;
the outlet temperature of the evaporator is an average outlet temperature of the evaporator.
As a further improved technical solution, the average outlet temperature of the evaporator is:
Figure BDA0002346267310000021
wherein,
Figure BDA0002346267310000022
representing the average outlet temperature of the evaporator, sigma the sum sign, H the number of said sub-evaporators, aiRepresenting the coefficient of the ith said sub-evaporator, a when said sub-evaporator has capacity for demandiIs 1, when the sub-evaporator has no capacity requirement, aiIs 0, TbiRepresents the outlet temperature of the ith said sub-evaporator.
As a further improvement, the adjusting the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree comprises:
obtaining a first opening variation of the expansion valve according to the suction superheat degree and the target suction superheat degree;
obtaining a second opening variation of the sub-expansion valve according to the average outlet temperature of the evaporator and the outlet temperature of the sub-evaporator;
and adjusting the opening degree of the sub-expansion valve corresponding to the sub-evaporator according to the first opening degree variation and the second opening degree variation.
As a further improvement, the adjusting the opening degree of the sub-expansion valve corresponding to the sub-evaporator according to the first opening degree variation and the second opening degree variation includes:
obtaining a total opening variation according to the first opening variation and the second opening variation;
and adjusting the opening degree of the expansion valve corresponding to the sub-evaporator according to the total opening degree variable quantity every other preset time.
As a further improved technical solution, before the obtaining of the suction superheat and the discharge superheat of the compressor of the air conditioner, the control method further comprises:
and when the air conditioner enters the high-temperature prevention protection mode, detecting the exhaust temperature of the compressor, and adjusting the opening degree of the expansion valve to exit the high-temperature prevention protection mode.
In a second aspect, an embodiment of the present invention provides a control system for an expansion valve of an air conditioner, where the control system includes: a processor, and a memory coupled to the processor,
the memory stores a control program of an expansion valve of the air conditioner, and the control program of the expansion valve of the air conditioner realizes the steps of the control method when being executed by the processor.
In a third aspect, an embodiment of the present invention provides an air conditioner, where the system includes the above-mentioned expansion valve of the air conditioner.
Compared with the prior art, the embodiment of the invention has the following advantages: the air conditioner obtains the suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner, obtains the target suction superheat degree according to the exhaust superheat degree, adjusts the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree, eliminates the deviation of a detection value and an actual value brought by a temperature sensing bulb by introducing the target suction superheat degree, and ensures the normal operation of the air conditioner.
Drawings
Fig. 1 is a first flowchart of a control method of an expansion valve of an air conditioner in the present invention.
Fig. 2a is a schematic view of a first structure of the air conditioner of the present invention.
Fig. 2b is a second structural schematic diagram of the air conditioner of the present invention.
Fig. 3 is a second flowchart of a control method of an expansion valve of an air conditioner in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The inventor finds that the return air superheat degree has certain limitation at low-temperature environment temperature, and the deviation between the suction superheat degree detected by the temperature sensing bulb and an actual value is large, so that the suction superheat degree detected and calculated has deviation, and if the suction superheat degree is not corrected, the normal operation of the air conditioner is influenced.
In order to solve the problems, in the embodiment of the invention, the air suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner are firstly obtained, then the target air suction superheat degree is obtained according to the exhaust superheat degree, the opening degree of an expansion valve of the air conditioner is adjusted according to the air suction superheat degree and the target air suction superheat degree, and the deviation between a detection value and an actual value caused by a temperature sensing bulb is eliminated by introducing the target air suction superheat degree, so that the normal operation of the air conditioner is ensured. And the actual exhaust superheat degree is used as auxiliary adjustment, so that the system is prevented from carrying liquid for a long time and the exhaust superheat degree is small, and the reliability of the compressor is improved.
In addition, for a multi-split air conditioner (the multi-split air conditioner means that one outdoor unit can be connected with a plurality of indoor units to operate, the indoor units are independently installed in each room and are independently controlled), the opening control of different indoor electronic expansion valves is the key for determining the performance, the energy efficiency and the comfort of the whole air conditioner. The deviation between the suction superheat degree detected in the prior art and an actual value is large, each indoor unit can be greatly influenced, and the system bias flow can exist when each indoor electronic expansion valve is not well controlled, so that the performance and the comfort of the whole machine are influenced. The method is suitable for the one-driving-multiple variable-frequency air conditioner, and can better improve the performance of the one-driving-multiple variable-frequency air conditioner.
The embodiment of the invention can be applied to the following scenes, firstly, the air conditioner can collect the suction superheat degree of a compressor of the air conditioner and transmit the target data set to the terminal, so that the terminal obtains the target suction superheat degree according to the exhaust superheat degree and transmits the target suction superheat degree to the air conditioner. And the air conditioner adjusts the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree.
It will be appreciated that in the application scenarios described above, the actions of the embodiments of the present invention are described as being performed in part by the air conditioner and in part by the terminal. However, such actions may be entirely terminal or entirely performed by the air conditioner. The invention is not limited in its implementation to the details of execution, provided that the acts disclosed in the embodiments of the invention are performed. The terminal includes a desktop terminal or a mobile terminal, such as a desktop computer, a tablet computer, a notebook computer, a smart phone, and the like. The air conditioner can be a variable frequency air conditioner, a multi-split air conditioner or a variable frequency multi-split air conditioner.
It should be noted that the above application scenarios are only presented to facilitate understanding of the present invention, and the embodiments of the present invention are not limited in any way in this respect. Rather, embodiments of the present invention may be applied to any scenario where applicable.
Referring to fig. 1 to 3, the present invention provides some embodiments of a method for controlling an expansion valve of an air conditioner.
The air conditioner includes: an evaporator 1, a compressor 2, a condenser 3, and an expansion valve 4, which are connected in sequence to form a circuit. If the air conditioner is a general air conditioner, as shown in fig. 2a, the air conditioner has only one evaporator 1 and 1 corresponding expansion valve 4. If the air conditioner is a multi-split air conditioner, the evaporator 1 includes at least 2 sub-evaporators, and the expansion valve 4 includes at least 2 sub-expansion valves, as shown in fig. 2b, the evaporator 1 has 4 sub-evaporators, and correspondingly, there are 4 sub-expansion valves, which are respectively disposed at the inlets of the sub-evaporators. The air conditioner also comprises a four-way valve 5, a liquid storage tank 6 and a throttling element 7; the first end of the four-way valve 5 is connected with the outlet of the evaporator 1, the second end is connected with the inlet of the liquid storage tank 6, the third end is connected with the inlet of the condenser 3, and the fourth end is connected with the outlet of the compressor 2. The condenser 3 is connected to the evaporator 1 via the throttle element 7. The outlet and the inlet of the compressor 2 are respectively provided with compressor temperature sensing bulbs 81 and 82 (a compressor temperature sensor may also be adopted) for detecting the temperatures (i.e., the discharge temperature and the suction temperature) of the refrigerant at the outlet and the inlet of the compressor 2, and the outlet and the inlet of the compressor 2 are respectively provided with pressure sensors 83 and 84 for detecting the pressures (i.e., the discharge pressure and the suction pressure) of the refrigerant at the outlet and the inlet of the compressor 2 as required. The outlets of the 4 sub-evaporators are respectively provided with evaporator temperature sensing bulbs 91 (evaporator temperature sensors can also be adopted), and the evaporator temperature sensing bulbs are respectively used for detecting the outlet temperature of each sub-evaporator. The condenser 3 is provided with a condenser thermal bulb 92 (a condenser temperature sensor may also be adopted) for detecting the temperature of the condenser 3.
The control method comprises the following steps:
and step S10, when the air conditioner enters the high temperature protection mode, detecting the discharge temperature Td of the compressor 2, and adjusting the opening degree of the expansion valve 4 to exit the high temperature protection mode.
When the air conditioner enters the high-temperature protection mode, corresponding adjustment is needed to exit the high-temperature protection mode. Specifically, the high temperature protection mode is exited by adjusting the opening degree of the expansion valve 4, but in other embodiments, the high temperature protection mode may be exited by other means.
In order to better acquire data to control the expansion valve, when the air conditioner exits the high temperature protection mode, the data is acquired and the expansion valve is finely controlled (i.e., step S100-step S300). And if the air conditioner enters the high-temperature prevention protection mode, roughly controlling the opening degree of the expansion valve 4 so as to obtain data after the air conditioner exits the high-temperature prevention protection mode, and finely controlling the expansion valve.
Specifically, when Td ≧ 102 ℃ is maintained for a duration exceeding the duration, the air conditioner enters a high temperature protection mode, and the expansion valve 4 is increased by a preset opening degree at intervals, and the duration may be 30s-90s, for example, set to 60 s. An interval time may be set to 20s-40s, for example to 30 s. The preset opening is 20-30P, for example, set to 24P. Td is more than or equal to 102 ℃, the exhaust temperature Td is maintained to be more than or equal to 102 ℃ in the duration time, the exhaust temperature is high, the air conditioner enters a high-temperature prevention protection mode, the opening degree of the expansion valve 4 is increased to reduce the exhaust temperature, and the air conditioner exits the high-temperature prevention protection mode.
By adjusting the opening degree of the expansion valve 4, better data can be obtained when the exhaust temperature Td is within a preset temperature range, thereby better adjusting the opening degree of the expansion valve. In one implementation manner of this embodiment, the preset temperature range is [70, 90 ], and when Td is greater than or equal to 70 ℃ and less than 90 ℃, the steps S100-S300 are performed.
When the exhaust temperature Td is within the preset temperature range, it indicates that the air conditioner is in a relatively stable period, and if the exhaust temperature Td is outside the preset temperature range, the opening degree of the expansion valve 4 may be correspondingly adjusted according to the condition of the exhaust temperature Td, so as to make the exhaust temperature Td within the preset temperature range, thereby performing the following steps to further adjust the opening degree of the expansion valve 4. Specifically, when Td ≧ 90 ℃, the expansion valve 4 is not adjusted down, that is, the expansion valve 4 may be adjusted up or not adjusted. When Td < 70 deg.c, the expansion valve 4 is not adjusted large, i.e. the expansion valve 4 may be adjusted small or not.
When the discharge temperature does not cause the air conditioner to enter the high temperature prevention protection mode, the fine control of the opening degree of the expansion valve 4 can be directly performed. According to the invention, the exhaust temperature is adjusted according to the steps, so that the exhaust temperature is in the preset temperature range as much as possible, and more accurate temperature data can be obtained, thereby more accurately adjusting the opening degree of the expansion valve 4.
And step S100, acquiring the suction superheat degree and the exhaust superheat degree of the compressor 2 of the air conditioner.
The suction superheat is the temperature difference between the temperature of the gas sucked by the compressor 2 and the corresponding saturation temperature at the corresponding pressure. The degree of superheat plays a significant role in the normal operation of the expansion valve 4. If the suction is completely non-overheated, the suction may generate return air and carry liquid, and even cause wet stroke liquid impact to damage the compressor 2. To avoid this, a certain degree of suction superheat is required to ensure that only dry vapor enters the compressor 2 (the presence of superheat, depending on the refrigerant properties, indicates complete evaporation of the liquid refrigerant). However, too high superheat also has the disadvantage that the high superheat causes the exhaust temperature (exhaust superheat) of the compressor 2 to increase, and the operation condition of the compressor 2 deteriorates and the service life is reduced. Therefore, the degree of superheat of the intake air should be controlled within a certain range.
The discharge superheat is the temperature difference between the temperature of the discharge pipe of the compressor 2 and the saturation temperature corresponding to the respective pressure. When the discharge superheat degree of the compressor 2 is too large, the suction specific volume is increased, and the refrigerant flow is reduced; when the discharge superheat of the compressor 2 is too small, liquid compression occurs, which not only degrades the performance of the air conditioner, but also causes a failure of the compressor 2.
Step S100 specifically includes:
step S110, determining an initial opening degree of the expansion valve 4 according to an ambient temperature of the condenser 3 of the air conditioner and an operation state of the evaporator 1 of the air conditioner.
Since the temperature sensing bulb is easily affected by the ambient temperature, especially in a low-temperature environment, the ambient temperature of the condenser 3 has a large influence on the temperature sensing bulb, thereby affecting the temperature measured by the temperature sensing bulb. The initial opening degree of the expansion valve 4 is determined according to the ambient temperature of the condenser 3 and the operating state of the evaporator 1, for example, when the ambient temperature of the condenser 3 is high, the initial opening degree of the expansion valve 4 is set high, whereas when the ambient temperature of the condenser 3 is low, the initial opening degree of the expansion valve 4 is set low. When the evaporator 1 is in low power operation, the initial opening degree of the expansion valve 4 is set to be high, whereas when the evaporator 1 is in high power operation, the initial opening degree of the expansion valve 4 is set to be low.
In a multi-split air conditioner, the evaporator 1 includes at least 2 sub-evaporators; the expansion valve 4 comprises at least 2 sub-expansion valves, and the sub-expansion valves are arranged in one-to-one correspondence with the sub-evaporators. The operation state of the evaporator 1 of the air conditioner includes the number of the sub-evaporators in operation. That is, in addition to considering that the evaporator 1 is in the high/low power operation, the number of the sub-evaporators is also considered. It is necessary to give the opening degree of the expansion valve 4 according to the ambient temperature of the condenser 3 and the number of the sub-evaporators and maintain the opening degree of the expansion valve 4 for a preset maintenance time, which may be set to 1-30 minutes, for example, to 3 minutes. Maintaining the opening degree of the expansion valve 4 may result in more accurate temperature data or pressure data, thereby more accurately adjusting the opening degree of the expansion valve 4.
And step S120, obtaining the suction superheat degree according to the outlet temperature of the evaporator 1 of the air conditioner and the suction temperature of the compressor 2 of the air conditioner.
When calculating the suction superheat of the compressor 2, the corresponding saturation temperature at the corresponding pressure is typically collected in the following manner: (1) collecting the temperature of the inlet of the evaporator 1; (2) collecting the temperature of the middle part of the evaporator 1; (3) the suction pressure of the compressor 2 is collected and converted into corresponding saturation temperature. In the embodiment of the invention, the outlet temperature of the evaporator 1 is collected as the corresponding saturation temperature under the corresponding pressure, and is collected through the temperature sensing bulb. Of course, in other embodiments, the corresponding saturation temperature at the corresponding pressure can be obtained by the above three methods.
The suction air superheat SH1 is the suction air temperature TH of the compressor 2 — the outlet temperature x of the evaporator 1, which is obtained by subtracting the outlet temperature of the evaporator 1 of the air conditioner from the suction air temperature of the compressor 2 of the air conditioner.
In the multi-split air conditioner, the outlet temperature of the evaporator 1 is specifically the average outlet temperature of the evaporator 1, that is, the outlet temperature of each sub-evaporator is collected and then averaged to obtain the average outlet temperature of the evaporator 1.
The average outlet temperature of the evaporator 1 is:
Figure BDA0002346267310000091
wherein,
Figure BDA0002346267310000092
represents the average outlet temperature of the evaporator 1, Σ represents the sum sign, H represents the number of said sub-evaporators, aiRepresents the coefficient of the ith sub-evaporator, a when the sub-evaporator has capacity to demand (i.e. is in operation)iIs 1, when the sub-evaporator has no capacity requirement (i.e. is in non-working state), aiIs 0, TbiRepresents the outlet temperature of the ith said sub-evaporator. Of course, different working states correspond to different capacity requirements, then a can be usediIs set to [0, 1]Numerical values within the ranges.
The suction superheat SH1 is obtained by subtracting the outlet temperature of the evaporator 1 from the suction temperature of the compressor 2, and in a multi-split air conditioner, the suction superheat SH1 is equal to the suction temperature TH of the compressor 2 — the average outlet temperature of the evaporator 1
Figure BDA0002346267310000093
And step S130, obtaining the exhaust superheat degree according to the exhaust temperature Td of the compressor 2 and the temperature of the condenser 3 of the air conditioner.
When calculating the degree of superheat of the discharge gas of the compressor 2, the corresponding saturation temperature at the corresponding pressure is generally acquired in the following manners: (1) collecting the temperature of an outlet of the condenser 3; (2) collecting the temperature of the middle part of the condenser 3; (3) and collecting the exhaust pressure of the condenser 3, and converting the exhaust pressure into the corresponding saturation temperature. In the embodiment of the invention, the temperature of the middle part of the condenser 3 is collected as the corresponding saturation temperature under the corresponding pressure, and is collected through the temperature sensing bulb. Of course, in other embodiments, the corresponding saturation temperature at the corresponding pressure may be obtained by using other two methods.
The exhaust superheat degree Δ Td is obtained by subtracting the temperature of the condenser 3 of the air conditioner from the exhaust temperature Td of the compressor 2, that is, the exhaust superheat degree Δ Td is equal to the exhaust temperature Td of the compressor 2 — the temperature T3 of the condenser 3 of the air conditioner.
And step S200, obtaining a target suction superheat SH2 according to the exhaust superheat.
In the embodiment, the target suction superheat SH2 is obtained through the exhaust superheat delta Td so as to avoid suction superheat errors in the adjusting process.
Specifically, a target suction superheat degree corresponding to the exhaust superheat degree in a one-to-one mode is obtained according to the exhaust superheat degree delta Td. The exhaust superheat degree delta Td and the target intake superheat degree SH2 can form a corresponding table, and after the exhaust superheat degree delta Td is obtained, the corresponding table is inquired to obtain the target intake superheat degree SH 2.
For example, when Δ Td ≦ 20, SH2 ≦ 5;
when the delta Td is more than or equal to 20 and less than or equal to 25, the SH2 is equal to 4;
when the delta Td is more than or equal to 25 and less than 30, the SH2 is equal to 3;
when the delta Td is more than or equal to 30 and less than 35, the SH2 is equal to 1;
when delta Td is more than or equal to 35 and less than 40, SH2 is equal to 0;
when the delta Td is more than or equal to 40 and less than 45, SH2 is equal to-1;
when Δ Td >45, SH2 ═ 2.
Of course, a corresponding table may be formed by setting the exhaust superheat degree Δ Td and the target suction superheat degree SH2 corresponding thereto as needed. For example, a correspondence table is set according to the ambient temperature of the condenser 3. In summary, the larger the exhaust superheat Δ Td, the smaller the target intake superheat SH2 corresponding thereto.
And step S300, adjusting the opening degree of an expansion valve 4 of the air conditioner according to the suction superheat degree and the target suction superheat degree.
Specifically, the opening degree of the expansion valve 4 is adjusted in accordance with the difference between the suction superheat and the target suction superheat.
In a general air conditioner, there is only one evaporator without forming a sub-evaporator, and there is only one corresponding expansion valve without forming a sub-expansion valve.
Step S300 includes:
step S310a is to obtain a first opening degree variation of the expansion valve based on the suction superheat and the target suction superheat.
The first opening degree change amount Δ P1 of the expansion valve 4 is equal to the intake air superheat SH1 — the target intake air superheat SH2, and here is equal to the intake air superheat SH1 TH-x. If Δ Td.gtoreq.42 ℃ and SH1-SH2<0, Δ P1 is set to 0. If Td.ltoreq.20 ℃ and SH1-SH2>0, then Δ P1 is likewise set to 0. Under other conditions, the calculation was carried out using Δ P1 ═ SH1-SH 2. Of course, the temperature of 42 ℃ and 20 ℃ can be set according to the requirement.
And step S320a, adjusting the opening degree of the expansion valve of the air conditioner by the first opening degree variation of the expansion valve at predetermined time intervals.
And adjusting the opening degree of the expansion valve according to the first opening degree variable quantity on the basis of the initial opening degree every other preset time T. That is, the first opening degree variation amount is added on the basis of the initial opening degree, where the first opening degree variation amount may be a positive value indicating that the first opening degree variation amount is increased on the basis of the initial opening degree or a negative value indicating that the first opening degree variation amount is decreased on the basis of the initial opening degree.
The sub-expansion valves corresponding to the sub-evaporators are adjusted differently in consideration of the fact that the states of the sub-evaporators are different from each other. Therefore, the refrigerants of the sub-evaporators are balanced, and the performance of each indoor unit of the air conditioner is improved.
Step S300 includes:
step S310b is to obtain a first opening degree variation of the expansion valve 4 from the intake superheat and the target intake superheat.
The first opening degree change amount Δ P1 of the expansion valve 4 is equal to the intake air superheat SH1 — the target intake air superheat SH 2. If Δ Td.gtoreq.42 ℃ and SH1-SH2<0, Δ P1 is set to 0. If Td.ltoreq.20 ℃ and SH1-SH2>0, then Δ P1 is likewise set to 0. Under other conditions, the calculation was carried out using Δ P1 ═ SH1-SH 2. Of course, the temperature of 42 ℃ and 20 ℃ can be set according to the requirement.
And realizing exhaust superheat adjustment and suction superheat adjustment of the air conditioner through the first opening variation. Of course, in the embodiment of the present invention, the opening degree of the expansion valve 4 may be adjusted according to the first opening degree variation after obtaining the first opening degree variation. The state of each sub-evaporator can be further combined to adjust so as to realize average pipe temperature adjustment.
Step S320b, obtaining a second opening degree variation of the sub-expansion valve according to the average outlet temperature of the evaporator 1 and the outlet temperature of the sub-evaporator.
When the sub-expansion valves are adjusted for the respective sub-evaporators, the second opening degree variation amounts calculated for the respective sub-evaporators are not completely the same. The second opening degree variation Δ
Figure BDA0002346267310000121
Wherein, Δ P2iSpecifically, the second opening degree variation of the sub expansion valve corresponding to the ith sub evaporator is set. And aiming at each sub-evaporator, different adjustments are carried out on the corresponding sub-expansion valves, so that the sub-evaporators can be balanced, the performance of all the sub-evaporators is comprehensively improved, the overload work of one sub-evaporator is avoided, and the cooperation effect among the sub-evaporators is enhanced.
Step S330b, adjusting the opening degree of the sub expansion valve according to the first opening degree variation and the second opening degree variation.
Specifically, the opening degree of the sub-expansion valve is adjusted according to the first opening degree variation and the second opening degree variation, that is, the exhaust superheat degree of the air conditioner is stabilized within a certain range through exhaust superheat adjustment, suction superheat adjustment and average tube temperature adjustment, and liquid return of the compressor 2 due to too low exhaust superheat degree is avoided.
Step S330b includes:
and step S331b, obtaining a total opening degree variation according to the first opening degree variation and the second opening degree variation.
Summing the first opening degree variation and the second opening degree variation to obtain a total opening degree variation, that is, the total opening degree variation Δ P is equal to the first opening degree variation Δ P1+ the second opening degree variation Δ P2i. Since the second opening degree variation amount corresponding to each of the sub-evaporators is not exactly the same, the obtained total opening degree variation amount also corresponds to each of the sub-evaporators.
Step S332b, adjusting the opening degree of the sub expansion valve corresponding to the sub evaporator according to the total opening degree variation at predetermined intervals.
And on the basis of the initial opening degree every other preset time T, adjusting the opening degree of the sub-expansion valve corresponding to each sub-evaporator according to the total opening degree variable quantity. That is, the total opening degree change amount is added on the basis of the initial opening degree, where the total opening degree change amount may be a positive value indicating that the opening degree of the sub-expansion valve is increased on the basis of the initial opening degree or a negative value indicating that the opening degree of the sub-expansion valve is decreased on the basis of the initial opening degree.
The invention is preferably adjusted according to the exhaust temperature, and can avoid the over-low exhaust superheat (step S10); then, according to the exhaust superheat adjustment, the return superheat adjustment (namely step S100-step S300) and the average pipe temperature adjustment (namely step S310-step S330b), the exhaust superheat degree of the air conditioner can be stabilized within a certain range, and liquid return of the compressor caused by too low exhaust superheat degree can be avoided; and the target value of the suction superheat degree is set through the actual value of the exhaust superheat so as to avoid return superheat degree errors in the adjusting process, and the refrigerant balance is realized through average pipe temperature adjustment.
Based on the control method of the expansion valve of the air conditioner, the invention also provides a preferred embodiment of a control system of the expansion valve of the air conditioner, which comprises the following steps:
the invention provides a control system of an expansion valve of an air conditioner, which comprises: a processor, and a memory connected to the processor, the memory storing a control program for an expansion valve of an air conditioner, the control program for the expansion valve of the air conditioner when executed by the processor implementing the steps of:
acquiring the suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner;
obtaining a target suction superheat degree according to the exhaust superheat degree;
and adjusting the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree.
Based on the control system of the expansion valve of the air conditioner, the invention also provides a preferred embodiment of the air conditioner, which comprises the following steps:
the air conditioner according to the embodiment of the present invention includes a control system for an expansion valve of the air conditioner according to any one of the above embodiments, which is specifically described above.
In summary, the present invention provides a method and a system for controlling an expansion valve of an air conditioner, and an air conditioner, wherein the method comprises the steps of: acquiring the suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner; obtaining a target suction superheat degree according to the exhaust superheat degree; and adjusting the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree. The air conditioner obtains the suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner, obtains the target suction superheat degree according to the exhaust superheat degree, adjusts the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree, eliminates the deviation of a detection value and an actual value brought by a temperature sensing bulb by introducing the target suction superheat degree, and ensures the normal operation of the air conditioner.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (7)

1. A control method of an expansion valve of an air conditioner, comprising the steps of:
when the air conditioner exits the high-temperature prevention protection mode, acquiring the suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner;
obtaining a target suction superheat degree according to the exhaust superheat degree;
adjusting the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree;
when the air conditioner exits the high-temperature protection mode, the air suction superheat degree and the exhaust superheat degree of a compressor of the air conditioner are obtained, and the method comprises the following steps:
when the air conditioner exits the high-temperature protection mode, determining the initial opening degree of the expansion valve according to the ambient temperature of a condenser of the air conditioner and the running state of an evaporator of the air conditioner;
obtaining the suction superheat degree according to the outlet temperature of the evaporator and the suction temperature of a compressor of the air conditioner;
obtaining the exhaust superheat degree according to the exhaust temperature of the compressor and the temperature of the condenser;
the evaporator comprises at least 2 sub-evaporators; the expansion valve comprises at least 2 sub-expansion valves, and the sub-expansion valves are arranged in one-to-one correspondence with the sub-evaporators;
the operation state of the evaporator of the air conditioner includes the number of the sub-evaporators in operation;
the outlet temperature of the evaporator is the average outlet temperature of the evaporator;
the adjusting of the opening degree of an expansion valve of the air conditioner according to the suction superheat degree and the target suction superheat degree comprises the following steps:
obtaining a first opening variation of the expansion valve according to the suction superheat degree and the target suction superheat degree; the first opening degree variation amount is a difference between the suction superheat degree and the target suction superheat degree;
obtaining a second opening variation of the sub-expansion valve according to the average outlet temperature of the evaporator and the outlet temperature of the sub-evaporator; the second opening degree variation is a difference between the outlet temperature of the sub-evaporator and the average outlet temperature;
and adjusting the opening degree of the sub-expansion valve corresponding to the sub-evaporator according to the first opening degree variation and the second opening degree variation.
2. The control method according to claim 1, wherein said adjusting an opening degree of an expansion valve of the air conditioner based on the suction superheat and the target suction superheat comprises:
obtaining a first opening variation of the expansion valve according to the suction superheat degree and the target suction superheat degree;
and adjusting the opening degree of an expansion valve of the air conditioner according to the first opening degree variable quantity of the expansion valve at intervals of preset time.
3. The control method of claim 1, wherein the average outlet temperature of the evaporator is:
Figure FDA0003141138990000021
wherein,
Figure FDA0003141138990000022
representing the average outlet temperature of the evaporator, sigma the sum sign, H the number of said sub-evaporators, aiRepresenting the coefficient of the ith said sub-evaporator, a when said sub-evaporator has capacity for demandiIs 1, when the sub-evaporator has no capacity requirement, aiIs 0, TbiRepresents the outlet temperature of the ith said sub-evaporator.
4. The control method according to claim 1, wherein the adjusting the opening degree of the sub-expansion valve corresponding to the sub-evaporator in accordance with the first opening degree change amount and the second opening degree change amount includes:
obtaining a total opening variation according to the first opening variation and the second opening variation;
and adjusting the opening degree of the sub-expansion valve corresponding to the sub-evaporator according to the total opening degree variable quantity every other preset time.
5. The control method according to claim 2, wherein before the obtaining of the suction superheat and the discharge superheat of the compressor of the air conditioner, the control method further comprises:
and when the air conditioner enters the high-temperature prevention protection mode, detecting the exhaust temperature of the compressor, and adjusting the opening degree of the expansion valve to exit the high-temperature prevention protection mode.
6. A control system for an expansion valve of an air conditioner, comprising: a processor, and a memory coupled to the processor,
the memory stores a control program for an expansion valve of an air conditioner, which when executed by the processor implements the steps of the control method according to any one of claims 1 to 5.
7. An air conditioner characterized by comprising a system of expansion valves of the air conditioner as claimed in claim 6.
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