CN114857664B - Multi-split air conditioner system - Google Patents

Multi-split air conditioner system Download PDF

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Publication number
CN114857664B
CN114857664B CN202210603688.7A CN202210603688A CN114857664B CN 114857664 B CN114857664 B CN 114857664B CN 202210603688 A CN202210603688 A CN 202210603688A CN 114857664 B CN114857664 B CN 114857664B
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Prior art keywords
state
sub
indoor
limit value
operation mode
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CN114857664A (en
Inventor
王善云
刘建凤
董筱凡
李鹏
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Qingdao Hisense Hitachi Air Conditioning System Co Ltd
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Qingdao Hisense Hitachi Air Conditioning System 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
    • F24F1/00—Room units for air-conditioning, e.g. separate or self-contained units or units receiving primary air from a central station
    • F24F1/0003—Room units for air-conditioning, e.g. separate or self-contained units or units receiving primary air from a central station characterised by a split arrangement, wherein parts of the air-conditioning system, e.g. evaporator and condenser, are in separately located units
    • 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
    • F24F11/62—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
    • F24F11/65—Electronic processing for selecting an operating mode
    • F24F11/67—Switching between heating and cooling modes
    • 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
    • F24F11/86—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling compressors within refrigeration or heat pump circuits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

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  • Engineering & Computer Science (AREA)
  • 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)
  • Thermal Sciences (AREA)
  • Human Computer Interaction (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

The invention discloses a multi-split system, comprising: the outdoor unit is provided with an outdoor heat exchanger, an outdoor throttling device connected with the outdoor heat exchanger and a compressor; the indoor units are provided with indoor heat exchangers and indoor throttling devices, and the indoor heat exchangers are respectively connected with the outdoor heat exchangers through refrigerant pipes; and the controller is configured to adjust the opening of the outdoor throttling device and the opening of the indoor throttling device according to the operation mode of the system, when the operation mode is a refrigerating operation mode, the outdoor throttling device is controlled to be fully opened, the opening of the indoor throttling device is not smaller than the lower limit value of the indoor throttling opening, and when the operation mode is a heating operation mode, the indoor throttling device is controlled to be fully opened, and the opening of the outdoor throttling device is not smaller than the lower limit value of the outdoor throttling opening. According to the multi-split air conditioner system, the minimum throttle opening of the inner machine and the outer machine is determined by setting the minimum valve opening control, so that the circulating refrigerant quantity of the system is ensured, the system is prevented from vacuumizing, and the user comfort and the compressor reliability are improved.

Description

Multi-split air conditioner system
Technical Field
The invention relates to the technical field of air conditioners, in particular to a multi-split air conditioner system.
Background
The multi-split air conditioner system is characterized in that one outdoor unit is connected with two or more indoor units through a pipe, wherein the outdoor side is subjected to air cooling heat exchange, and the indoor side is subjected to direct evaporation heat exchange.
Along with the increasingly strict cost requirements, in order to develop products with low cost and meeting the reliability of the products, the good multi-air-conditioner products cancel the low pressure sensor, and the low pressure of the system is calculated through numerical values such as temperature, the low pressure of the transition stage of the scheme under low-temperature and high-temperature working conditions is calculated inaccurately, and some of the scheme can be calculated inaccurately for a long time, so that the compressor is in a vacuum pumping state, the comfort of a user is poor, and the compressor is easy to damage.
Because the multi-split air conditioner has the characteristics of large difference in length of connecting pipes, large difference in proportion between the inner machine and the outer machine, partial difference in operation load of the multi-split air conditioner and the like, the situation that low pressure is inaccurate in calculation can occur under the condition of individual working conditions or individual on-line schemes according to the calculation mode, especially in the immediately starting stage of a unit, the whole system is not stably operated, the situation that the system is vacuumized easily occurs, the reaction of the low pressure is delayed due to the fact that the low pressure is inferred by temperature, the low pressure calculated according to the temperature is not low (the actual low pressure is low), the frequency of a compressor, the rotation speed of a fan, the control of a throttling device and the like are not changed in the direction of improving the low pressure, the low pressure can be continuously reduced or continuously vacuumized, the comfort of a user can not be ensured, and the compressor is easily damaged.
The system has the vacuumizing condition, is difficult to verify in a large amount of test data, can be concluded according to a large amount of practical application conditions, compressor fault analysis data and the like, and can be concluded according to specific dissection and detailed analysis, so that the later maintenance and cause searching are increased in a large number of difficulties and workload.
Disclosure of Invention
In order to solve the technical problems that the compressor is vacuumized when the low pressure is higher than an actual value and the system performance is reduced and the compressor is damaged due to the fact that the low pressure is calculated in the prior art, the invention provides a multi-split air conditioner system, and the problems can be solved.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a multi-split system, which comprises:
the outdoor unit is provided with an outdoor heat exchanger, an outdoor throttling device connected with the outdoor heat exchanger and a compressor;
the indoor units are provided with indoor heat exchangers and indoor throttling devices connected with the indoor heat exchangers, and the indoor heat exchangers are respectively connected with the outdoor heat exchangers through multi-path refrigerant pipes; further comprises:
and the controller is configured to adjust the opening degrees of the outdoor throttling device and the indoor throttling device according to the operation mode of the system, when the operation mode is a refrigerating operation mode, the outdoor throttling device is controlled to be fully opened, the opening degree of the indoor throttling device is not smaller than the lower limit value of the indoor throttling opening degree, and when the operation mode is a heating operation mode, the indoor throttling device is controlled to be fully opened, and the opening degree of the outdoor throttling device is not smaller than the lower limit value of the outdoor throttling opening degree.
In some embodiments of the invention, the controller further comprises:
judging the current running state, wherein the running state comprises a transition running state and a stable running state;
the refrigerating operation mode is respectively corresponding to at least one group of preset indoor throttle opening lower limit value sets in a transitional operation state and a stable operation state, and the indoor throttle opening lower limit value sets are composed of indoor throttle opening lower limit values of all indoor units;
when the operation mode is a refrigeration operation mode, acquiring an indoor throttle opening lower limit value set according to the current operation state, and controlling the opening of each indoor throttle device to be not smaller than the indoor throttle opening lower limit value corresponding to the indoor throttle device;
the heating operation mode is respectively corresponding to at least one preset lower limit value of the outdoor throttle opening in a transitional operation state and a stable operation state;
and when the operation mode is a heating operation mode, acquiring the lower limit value of the outdoor throttle opening according to the current operation state.
In some embodiments of the present invention, the method for determining the current running state is: when the compressor is initially started, the compressor is in a transitional running state;
and performing state transition judgment, and when the state transition condition is met, judging that the current running state is transited from the transitional running state to the stable running state.
In some embodiments of the present invention, the method for determining a current operating state further includes:
acquiring high pressure, low pressure and starting operation time;
the state transition judgment comprises the following steps: and judging that the state transition condition is met when any one of the high pressure exceeding a preset high pressure upper limit value, the low pressure being lower than a preset low pressure lower limit value, the starting operation time reaching a preset time and the ratio of the high pressure to the low pressure exceeding a preset value is met.
In some embodiments of the invention, the steady-state operating state includes a first sub-state, a second sub-state, and a third sub-state;
when the running state is a stable running state, judging the sub-state;
the refrigerating operation mode is respectively provided with a group of preset indoor throttle opening lower limit value sets corresponding to each sub-state, and the magnitude relation of the indoor throttle opening lower limit values corresponding to the three sub-states is as follows in sequence from big to small: a second sub-state, a first sub-state, and a third sub-state;
the heating operation mode is respectively provided with a preset lower limit value of the outdoor throttle opening corresponding to each sub-state, and the magnitude relation of the lower limit values of the outdoor throttle opening corresponding to the three sub-states is as follows in sequence from big to small: a second sub-state, a first sub-state, and a third sub-state.
In some embodiments of the present invention, when the operation state is a stable operation state, the method further includes performing a transition determination between sub-states, and when a transition condition between sub-states is satisfied, determining that the current operation state is to be transitioned from the current sub-state to another sub-state.
In some embodiments of the present invention, a method for determining migration between sub-states in a cooling operation mode includes:
acquiring the current exhaust temperature and low pressure, and judging to migrate from the current sub-state to the second sub-state when the exhaust temperature exceeds a set first temperature limit value or the low pressure is lower than a set first pressure limit value;
if the current state is the second sub-state and the exhaust temperature is lower than the set second temperature limit value and the low pressure exceeds the set second pressure limit value, judging that the current state is shifted to the first sub-state from the second sub-state;
if the current state is the first sub-state, and the exhaust temperature is lower than the set third temperature limit value and the duration reaches the first time limit value, judging that the current state is shifted to the third sub-state from the current first sub-state;
the method for judging the migration between sub-states in the heating operation mode comprises the following steps:
acquiring the current exhaust temperature and low pressure, and judging to migrate from the current sub-state to the second sub-state when the exhaust temperature exceeds a set fourth temperature limit value or the low pressure is lower than a set fourth pressure limit value;
if the current state is the second sub-state and the exhaust temperature is lower than the set fourth temperature limit value and the low pressure exceeds the set second pressure limit value, judging that the current state is shifted to the first sub-state from the second sub-state;
and if the current state is the first sub-state, and the exhaust temperature is lower than the set sixth temperature limit value and the duration reaches the second time limit value, judging that the current state is shifted to the third sub-state from the first sub-state.
In some embodiments of the invention, the low pressure is obtained from a look-up table based on the inspiratory saturation temperature, comprising:
when the operation mode is a refrigeration operation mode, the air suction saturation temperature X=T1l+K1, wherein T11 is the indoor unit liquid pipe temperature, and K1 is the compensation coefficient in the refrigeration operation mode;
when the operation mode is a heating operation mode, the suction saturation temperature x=tli2+k1, wherein T12 is the outdoor unit heat exchanger temperature, and K2 is the compensation coefficient in the heating operation mode.
In some embodiments of the present invention, the current operating state is determined to migrate from the transitional operating state to the first sub-state when the inter-state migration condition is satisfied.
In some embodiments of the present invention, the current operating state transitions to a transitional operating state when the compressor is shut down and restarted.
Compared with the prior art, the technical scheme of the invention has the following technical effects:
according to the multi-split air conditioner system, the minimum throttle opening value of the inner and outer machines is determined by setting the minimum valve opening control in the control, so that the circulating refrigerant quantity of the system is ensured, the condition that the system is vacuumized under special conditions is prevented, and the user comfort and the compressor reliability are further improved. In addition, this scheme is through adjusting outdoor throttling arrangement and indoor throttling arrangement's aperture according to the mode of operation of system, namely during the refrigeration mode of operation, control outdoor throttling arrangement is full-open, controls the aperture of adjusting indoor throttling arrangement, and indoor heat exchanger is as the condenser this moment, can guarantee certain supercooling degree, guarantees that indoor throttling arrangement throttles preceding refrigerant is liquid, is favorable to the ability to promote and guarantees throttling arrangement and adjusts stability. When the heating operation mode is adopted, the indoor throttling device is controlled to be fully opened, the opening of the outdoor throttling device is controlled and adjusted, the unit operation refrigerant quantity can be guaranteed, the system circulation refrigerant quantity is avoided to be small, and further the conditions that the system is vacuumized, the user comfort is poor and the reliability of the compressor cannot be guaranteed are avoided.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a system schematic diagram of an embodiment of a multi-split system according to the present invention;
FIG. 2 is a flow chart of a refrigerant in a cooling operation mode in an embodiment of the multi-split system according to the present invention;
FIG. 3 is a flow chart of a refrigerant in a heating operation mode in an embodiment of the multi-split system according to the present invention;
FIG. 4 is a schematic diagram of a throttling device during a cooling operation mode in an embodiment of a multi-split system according to the present invention;
FIG. 5 is a schematic diagram of a throttle device adjustment during a heating mode of operation in an embodiment of a multi-split system according to the present invention;
FIG. 6 is a state transition diagram of a multi-split system according to an embodiment of the present invention;
FIG. 7 is a general diagram illustrating migration between sub-states of an embodiment of a multi-split system according to the present invention;
FIG. 8 is a schematic diagram illustrating migration between sub-states of a multi-split system according to another embodiment of the present invention;
FIG. 9 is a schematic diagram illustrating migration between sub-states of a multi-split system according to another embodiment of the present invention;
FIG. 10 is a schematic diagram illustrating migration between sub-states of a multi-split system according to another embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that the terms "mounted," "connected," and "coupled" are to be construed broadly, as well as, for example, fixedly coupled, detachably coupled, or integrally coupled, unless otherwise specifically indicated and defined. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art. In the description of the above embodiments, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
The terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
Example 1
The multi-split system provided by the embodiment executes refrigeration and heating cycles of the multi-split system by using the compressor, the condenser, the throttling device and the evaporator. The refrigerating and heating cycle includes a series of processes involving compression, condensation, expansion and evaporation, and refrigerating or heating an indoor space.
The low-temperature low-pressure refrigerant enters the compressor, the compressor compresses the refrigerant gas into a high-temperature high-pressure state, and the compressed refrigerant gas is discharged. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.
The throttle device expands the liquid-phase refrigerant in a high-temperature and high-pressure state formed by condensation in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the throttle device and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator may achieve a cooling effect by exchanging heat with a material to be cooled using latent heat of evaporation of a refrigerant. In the whole cycle, the multi-split system can adjust the temperature of the indoor space.
In the multi-split air conditioner system provided in this embodiment, one outdoor unit and a plurality of indoor units are provided. The outdoor unit is a part of refrigeration cycle, which comprises a compressor, an outdoor heat exchanger and an outdoor fan, wherein the outdoor heat exchanger is connected with an outdoor throttling device, the indoor unit is provided with an indoor heat exchanger and an indoor throttling device connected with the indoor heat exchanger, and a plurality of indoor heat exchangers are respectively connected with the outdoor heat exchanger through a plurality of paths of refrigerant pipes.
The indoor heat exchanger and the outdoor heat exchanger function as a condenser or an evaporator. When the indoor heat exchanger is used as a condenser, the multi-split system executes a heating mode; when the indoor heat exchanger is used as an evaporator, the multi-split system performs a cooling mode.
The mode of converting the indoor heat exchanger and the outdoor heat exchanger into a condenser or an evaporator generally adopts a four-way valve, and the arrangement of a conventional air conditioner is specifically referred to and will not be described herein.
The refrigeration working principle of the multi-split air conditioner system is as follows: the compressor works to enable the interior of an indoor heat exchanger (in an indoor unit, an evaporator at the moment) to be in an ultralow pressure state, liquid refrigerant in the indoor heat exchanger is rapidly evaporated to absorb heat, air blown out by an indoor fan at the tail end of an air conditioner is cooled by an indoor heat exchanger coil and then changed into cold air to be blown into the indoor, the evaporated refrigerant is condensed into liquid state in a high-pressure environment in an outdoor heat exchanger (in an outdoor unit, a condenser at the moment) after being pressurized by the compressor, heat is released, the heat is dissipated into the atmosphere by the outdoor fan, and the refrigerating effect is achieved through circulation.
The heating working principle of the multi-split system is as follows: the gaseous refrigerant is pressurized by the compressor to become high-temperature high-pressure gas, and enters the indoor heat exchanger (a condenser at the moment), so that the gaseous refrigerant is condensed, liquefied and released heat to become liquid, and meanwhile, the indoor air is heated, so that the aim of improving the indoor temperature is fulfilled. The liquid refrigerant is decompressed by the throttling device, enters the outdoor heat exchanger (an evaporator at the moment), evaporates and absorbs heat to become gas, and simultaneously absorbs heat of outdoor air (the outdoor air becomes colder) to become gaseous refrigerant, and enters the compressor again to start the next cycle.
Referring to the multiple on-line system shown in fig. 1, each indoor unit corresponds to one indoor throttling device, for example, the multiple on-line system shown in fig. 1 includes two indoor throttling devices, namely, a first indoor throttling device 141 and a second indoor throttling device 142.
As shown in fig. 2, during cooling, the compressor 11 discharges air, the air is diverted through the four-way valve 12 to the outdoor heat exchanger 13, the refrigerant is condensed, the air is throttled by the throttle device, the throttled refrigerant enters a plurality of indoor heat exchangers (a first indoor heat exchanger 151 and a second indoor heat exchanger 152 shown in fig. 1) through pipes to evaporate and absorb heat, and then the air returns to the compressor 11 through the four-way valve 12. The flow direction of the refrigerant during cooling is shown by an arrow in fig. 2.
As shown in fig. 3, during heating, the exhaust gas of the compressor 11 is diverted through the four-way valve 12, enters the multipath indoor heat exchangers (151 and 152) through the pipelines to be condensed, throttles through the throttling device after being condensed, enters the outdoor heat exchanger 13 to evaporate and absorb heat after being throttled, and returns to the compressor 11 after being diverted through the four-way valve 12. Indoor units in the multi-split air conditioner can be partially opened and partially closed.
The independent start and stop of the plurality of indoor units can be realized through a wire controller or a wireless control terminal matched with the indoor units. The flow direction of the refrigerant during heating is shown by an arrow in fig. 3.
The controller may be a local controller, such as a single-chip microcomputer integrated on a motherboard of the outdoor unit, or a remote controller, such as a cloud platform; the cloud platform can send corresponding valve adjusting instructions to the local controller, and the local controller executes corresponding control.
Some multi-split systems further include a gas-liquid separator 17 for separating the gas and liquid of the refrigerant returned to the compressor, so as to prevent the compressor 11 from being damaged due to liquid impact.
The principle that the local controller outputs a voltage signal to adjust the opening degree (step number) of the throttle device is well known in the art, and the real-time opening degree of the throttle device is obtained according to the actual load of the air-conditioning room by using a control method in the prior art, such as PID control or fuzzy control, and the above description will not be given in detail. The set opening is measured by a professional technician under the experimental condition, and is a set value of a corresponding model, and the set opening is stored in the controller in advance for calling.
Along with the increasingly strict cost requirements, in order to develop products with low cost and meeting the reliability of the products, the multi-air-conditioner products cancel the low pressure sensor, the low pressure of the system is calculated through numerical values such as temperature, the situation that the low pressure is calculated inaccurately can occur under the condition of individual working conditions or individual on-line schemes in a calculating mode, especially in the immediately starting stage of a unit, the whole system does not stably operate, the system vacuumizing condition easily occurs, the low pressure is inferred by temperature, the temperature reaction of the system is delayed, the low pressure calculated according to the temperature is not low (the actual low pressure is low), the compressor frequency, the fan speed, the throttle device control and the like can not change the direction of improving the low pressure to control, the low pressure can be continuously lowered or continuously vacuumized, the comfort of a user can not be ensured, and the compressor is also easily damaged.
In order to solve the above problems, the multi-split system of the present invention further includes a controller configured to adjust the opening degrees of the outdoor throttling device 16 and the indoor throttling device according to the operation mode of the system, when the operation mode is the cooling operation mode, as shown in fig. 1 and 4, the outdoor throttling device 16 is controlled to be fully opened, the opening degree of the indoor throttling device is not less than the lower limit value of the indoor throttling opening degree, and the outdoor throttling device is controlled to be fully opened.
When the operation mode is the heating operation mode, as shown in fig. 1 and 5, the indoor throttle device is controlled to be fully opened, and the opening degree of the outdoor throttle device 16 is not smaller than the lower limit value of the outdoor throttle opening degree. The indoor throttling device is fully opened, the control can ensure the refrigerant quantity of the unit operation, the system is prevented from being small in circulating refrigerant quantity, and further the conditions that the system is vacuumized, the user comfort is poor and the reliability of the compressor cannot be guaranteed are avoided.
According to the multi-split air conditioner system, the minimum valve opening control is set in the control process, so that the minimum expansion valve opening of the inner and outer machines is determined, the circulating refrigerant quantity of the system is ensured, the condition that the system is vacuumized under special conditions is prevented, and the user comfort and the compressor reliability are further improved. In addition, this scheme is through adjusting outdoor throttling arrangement and indoor throttling arrangement's aperture according to the mode of operation of system, namely during the refrigeration mode of operation, control outdoor throttling arrangement is full-open, controls the aperture of adjusting indoor throttling arrangement, and indoor heat exchanger is as the condenser this moment, can guarantee certain supercooling degree, guarantees that indoor throttling arrangement throttles preceding refrigerant is liquid, is favorable to the ability to promote and guarantees throttling arrangement and adjusts stability. When the heating operation mode is adopted, the indoor throttling device is controlled to be fully opened, the opening of the outdoor throttling device is controlled and adjusted, the unit operation refrigerant quantity can be guaranteed, the system circulation refrigerant quantity is avoided to be small, and further the conditions that the system is vacuumized, the user comfort is poor and the reliability of the compressor cannot be guaranteed are avoided.
The minimum opening of the indoor and outdoor throttling device in the control scheme is larger, the problem of system vacuumizing can be solved, but the system circulation refrigerant quantity is large under special conditions, the risk of system liquid return still influences the reliability of the compressor, so that the scheme is further optimized, the product operation process is divided into transition and stable operation, and migration is carried out between different states according to set conditions.
In some embodiments of the present invention, as shown in fig. 6, the controller further includes: and judging the current running state, wherein the running state comprises a transitional running state and a stable running state.
The refrigerating operation mode is respectively corresponding to at least one group of preset indoor throttling opening lower limit value sets in a transitional operation state and a stable operation state, wherein the indoor throttling opening lower limit value sets are composed of indoor throttling opening lower limit values of all indoor units.
The working condition environments are complex and changeable in the running process of the multi-split system, and corresponding control parameters are different in different working condition environments so as to achieve the optimal working condition. The current working conditions of the control parameters are matched best by setting respective throttle opening lower limit values in the transitional running state and the steady running state respectively, so that the optimal working state is achieved.
The throttle opening lower limit value corresponding to different running states can be determined through experiments.
The throttle opening lower limit value is determined by the following steps: the control system starts to operate, and the parameters such as low pressure, high pressure, air suction temperature, exhaust temperature and the like are detected in real time by adopting the pressure sensor, and COP performance coefficients and the like can be calculated according to the existing formula algorithm, so that the opening lower limit value of the corresponding throttling device when the system can safely operate and simultaneously meets the higher energy efficiency ratio as much as possible is determined. And simultaneously recording the current low pressure calculated value calculated by adopting a low pressure calculation formula, correlating the low pressure calculated value with the opening lower limit value of the throttling device, and storing the low pressure calculated value in a storage unit of the system.
In actual use, the multi-split system is not provided with a pressure sensor for measuring low pressure, but calculates low pressure by adopting the same low pressure calculation formula. The scheme can still save the hardware cost of hardware detection which is not suitable for low-pressure, and can improve the running safety and reliability of the system.
The low pressure and the high pressure parameters are actually measured in the experimental environment, so that the safety and the energy efficiency ratio in different running states are accurately evaluated and determined, the low pressure calculated value is related to the opening lower limit value of the throttling device in the process of correlation, the low pressure calculated value is matched with a sensor for measuring the low pressure, no matter how large the deviation between the calculated value and the actual value is, and the actual value corresponding to the calculated value limit value set in the scheme is the limit value which is experimentally measured and can meet the conditions. According to the scheme, error compensation is not required to be carried out on the low-pressure calculated value, calculation time is further saved, and the control reaction speed is improved.
When the operation mode is a refrigeration operation mode, acquiring a set of lower limit values of the indoor throttle opening according to the current operation state, and controlling the opening of each indoor throttle device to be not smaller than the lower limit value of the indoor throttle opening corresponding to the indoor throttle device.
The refrigerating and heating capacities of the different indoor units are not necessarily the same, so that the opening lower limit values of the corresponding indoor throttling devices are not necessarily the same, and in some embodiments of the present invention, the indoor throttling opening lower limit values are respectively and correspondingly set for the indoor units, so as to form an indoor throttling opening lower limit value set. In actual operation control, the indoor throttle device searches for the respective lower limit value of the indoor throttle opening as a control limit value so that the opening control is not lower than the lower limit value.
The heating operation mode is respectively corresponding to at least one preset lower limit value of the outdoor throttle opening in a transitional operation state and a stable operation state.
The indoor throttling device is fully opened in the heating operation mode, and the control is realized by adjusting the opening of the outdoor throttling device. And only one outdoor throttle device is provided, so that a lower limit value of the outdoor throttle opening is preset for each state. When a certain running state comprises a plurality of sub-states, the lower limit value of the outdoor throttle opening is preset for each sub-state.
And when the operation mode is a heating operation mode, acquiring the lower limit value of the outdoor throttle opening according to the current operation state.
In some embodiments of the present invention, the method for determining the current running state is: when the compressor is initially started, the compressor is in a transitional running state.
The running state is changed according to the actual working condition, and the method further comprises the step of performing state transition judgment, and when the state transition condition is met, the current running state is judged to be transited from the transitional running state to the stable running state.
In some embodiments of the present invention, the method for determining a current operating state further includes:
acquiring high pressure, low pressure and starting operation time;
the state transition judgment comprises the following steps: and judging that the state transition condition is met when any one of the high pressure exceeding a preset high pressure upper limit value, the low pressure being lower than a preset low pressure lower limit value, the starting operation time reaching a preset time and the ratio of the high pressure to the low pressure exceeding a preset value is met.
In some embodiments of the present invention, as shown in fig. 7, the steady-state operation state includes a first sub-state, a second sub-state, and a third sub-state.
When the running state is the stable running state, the method further comprises judging the sub-state.
The refrigerating operation mode is respectively provided with a group of preset indoor throttle opening lower limit value sets corresponding to each sub-state, and the size relations of the indoor throttle opening lower limit values corresponding to the three sub-states are as follows in sequence from big to small: a second sub-state, a first sub-state, and a third sub-state.
The heating operation mode is respectively provided with a preset lower limit value of the outdoor throttle opening corresponding to each sub-state, and the magnitude relation of the lower limit values of the outdoor throttle opening corresponding to the three sub-states is as follows in sequence from big to small: a second sub-state, a first sub-state, and a third sub-state.
During the cooling operation of the unit, the different indoor throttle opening IE1, IE2, IE3 … … IEn sets minimum opening values D1, D2, D3 … … Dn in the transitional operation state, minimum opening values E1, E2, E3 … … En in the first sub-state of the steady operation, minimum opening values F1, F2, F3 … … Fn in the second sub-state of the steady operation, and minimum opening values G1, G2, G3 … … Gn in the third sub-state of the steady operation, wherein the values of D1, D2, D3 … … Dn, E1, E2, E3 … … En, F1, F2, F3 … … Fn, G1, G2, G3 … … Gn are determined by test data. In the transitional operating state:
the opening degree IE1, IE2, IE3 … … IEn of different indoor throttle devices needs to be not smaller than the corresponding lower limit value of the indoor throttle opening degree, namely: IE1 is larger than or equal to D1, IE2 is larger than or equal to D2, IE3 is larger than or equal to D3 … … IEn is larger than or equal to Dn.
In the first sub-state of steady operation:
the opening degree IE1, IE2, IE3 … … IEn of different indoor throttle devices needs to be not smaller than the corresponding lower limit value of the indoor throttle opening degree, namely: IE1 is greater than or equal to E1, IE2 is greater than or equal to E2, IE3 is greater than or equal to E3 … … IEn is greater than or equal to En.
In the second sub-state of steady operation:
the opening degree IE1, IE2, IE3 … … IEn of different indoor throttle devices needs to be not smaller than the corresponding lower limit value of the indoor throttle opening degree, namely: IE1 is greater than or equal to F1, IE2 is greater than or equal to F2, IE3 is greater than or equal to F3 … … IEn is greater than or equal to Fn.
In the third sub-state of steady operation:
the opening degree IE1, IE2, IE3 … … IEn of different indoor throttle devices needs to be not smaller than the corresponding lower limit value of the indoor throttle opening degree, namely: IE1 is greater than or equal to G1, IE2 is greater than or equal to G2, IE3 is greater than or equal to G3 … … IEn is greater than or equal to Gn.
In some embodiments of the present invention, when the operation state is a stable operation state, the method further includes performing a transition determination between sub-states, and when a transition condition between sub-states is satisfied, determining that the current operation state is to be transitioned from the current sub-state to another sub-state.
In some embodiments of the present invention, a method for determining migration between sub-states in a cooling operation mode includes:
the current exhaust temperature and the low pressure are acquired, and when the exhaust temperature exceeds the set first temperature limit value or the low pressure is lower than the set first pressure limit value, as shown in fig. 8, the transition from the current sub-state to the second sub-state is determined. Namely, the lower limit value of the indoor throttle opening is increased, and the system is prevented from vacuumizing.
As shown in fig. 9, if the current state is the second sub-state, and the exhaust temperature is lower than the set second temperature limit value and the low pressure exceeds the set second pressure limit value, it is determined that the current second sub-state is shifted to the first sub-state, that is, the lower limit value of the indoor throttle opening is reduced, so that the system is prevented from having a liquid return risk.
As shown in fig. 10, if the current first sub-state is the first sub-state, and the exhaust temperature is satisfied to be lower than the set third temperature limit value and the duration reaches the first time limit value, it is determined that the current first sub-state is shifted to the third sub-state. The lower limit value of the indoor throttle opening is further reduced, and the liquid return risk of the system is prevented.
The method for judging the migration between sub-states in the heating operation mode comprises the following steps:
and acquiring the current exhaust temperature and the low pressure, and judging that the current sub-state is shifted to the second sub-state when the exhaust temperature exceeds the set fourth temperature limit value or the low pressure is lower than the set fourth pressure limit value. Namely, the lower limit value of the outdoor throttle opening is increased to prevent the system from vacuumizing.
And if the current state is the second sub-state and the exhaust temperature is lower than the set fourth temperature limit value and the low pressure exceeds the set second pressure limit value, judging that the state is shifted from the current second sub-state to the first sub-state. Namely, the lower limit value of the outdoor throttle opening is reduced, and the system is prevented from having liquid return risk.
And if the current state is the first sub-state, and the exhaust temperature is lower than the set sixth temperature limit value and the duration reaches the second time limit value, judging that the current state is shifted to the third sub-state from the first sub-state. Namely, the lower limit value of the outdoor throttle opening is further reduced, and the system is prevented from having liquid return risk.
In some embodiments of the invention, the low pressure is obtained from a look-up table based on the inspiratory saturation temperature, comprising:
when the operation mode is a refrigeration operation mode, the air suction saturation temperature X=T1l+K1, wherein T11 is the indoor unit liquid pipe temperature, and K1 is the compensation coefficient in the refrigeration operation mode;
when the operation mode is a heating operation mode, the suction saturation temperature x=tli2+k1, wherein T12 is the outdoor unit heat exchanger temperature, and K2 is the compensation coefficient in the heating operation mode.
In some embodiments of the present invention, the current operating state is determined to migrate from the transitional operating state to the first sub-state when the inter-state migration condition is satisfied.
In some embodiments of the invention, the method further comprises transitioning from the current operating state to a transitional operating state when the compressor is shut down and restarted.
After the control of the preferred scheme is executed, the opening of the throttling device is correspondingly adjusted according to different conditions, so that the control device can adapt to various online schemes, tubing lengths and various working conditions, can well meet user comfort and can ensure the reliability of the compressor.
In the description of the above embodiments, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (10)

1. A multi-split system comprising:
the outdoor unit is provided with an outdoor heat exchanger, an outdoor throttling device connected with the outdoor heat exchanger and a compressor;
the indoor units are provided with indoor heat exchangers and indoor throttling devices connected with the indoor heat exchangers, and the indoor heat exchangers are respectively connected with the outdoor heat exchangers through multi-path refrigerant pipes;
characterized by further comprising:
the controller is configured to adjust the opening degrees of the outdoor throttling device and the indoor throttling device according to the operation mode of the system, when the operation mode is a refrigerating operation mode, the outdoor throttling device is controlled to be fully opened, the opening degree of the indoor throttling device is not smaller than the lower limit value of the indoor throttling opening degree, and when the operation mode is a heating operation mode, the indoor throttling device is controlled to be fully opened, and the opening degree of the outdoor throttling device is not smaller than the lower limit value of the outdoor throttling opening degree;
the operation states comprise a transition operation state and a stable operation state, the stable operation state comprises a plurality of sub-states, the refrigeration operation mode corresponds to different indoor throttle opening lower limit values respectively in each operation state, and the heating operation mode corresponds to different outdoor throttle opening lower limit values respectively in each operation state;
the controller further includes controlling the sub-state according to the transition between the discharge temperature and the low pressure, such that the sub-state transitions toward increasing the lower limit of the indoor throttle opening or the lower limit of the outdoor throttle opening when the discharge temperature exceeds the corresponding temperature limit or the low pressure is lower than the corresponding pressure limit, and the sub-state transitions toward increasing the lower limit of the indoor throttle opening when the discharge temperature exceeds the corresponding temperature limit or the low pressure is lower than the corresponding pressure limit, and the sub-state transitions toward increasing the lower limit of the outdoor throttle opening when the discharge temperature exceeds the corresponding temperature limit or the low pressure is lower than the corresponding pressure limit.
2. The multi-split system of claim 1, wherein the controller further comprises:
judging the current running state;
the refrigerating operation mode is respectively corresponding to at least one group of preset indoor throttle opening lower limit value sets in a transitional operation state and a stable operation state, and the indoor throttle opening lower limit value sets are composed of indoor throttle opening lower limit values of all indoor units;
when the operation mode is a refrigeration operation mode, acquiring an indoor throttle opening lower limit value set according to the current operation state, and controlling the opening of each indoor throttle device to be not smaller than the indoor throttle opening lower limit value corresponding to the indoor throttle device;
the heating operation mode is respectively corresponding to at least one preset lower limit value of the outdoor throttle opening in a transitional operation state and a stable operation state;
and when the operation mode is a heating operation mode, acquiring the lower limit value of the outdoor throttle opening according to the current operation state.
3. The multi-split system according to claim 2, wherein the method for determining the current operation state is: when the compressor is initially started, the compressor is in a transitional running state;
and performing state transition judgment, and when the state transition condition is met, judging that the current running state is transited from the transitional running state to the stable running state.
4. The multi-split system of claim 3, wherein the method of determining the current operating state further comprises:
acquiring high pressure, low pressure and starting operation time;
the state transition judgment comprises the following steps: and judging that the state transition condition is met when any one of the high pressure exceeding a preset high pressure upper limit value, the low pressure being lower than a preset low pressure lower limit value, the starting operation time reaching a preset time and the ratio of the high pressure to the low pressure exceeding a preset value is met.
5. The multi-split system of claim 2, wherein the steady state operation state comprises a first sub-state, a second sub-state, and a third sub-state;
when the running state is a stable running state, judging the sub-state;
the refrigerating operation mode is respectively provided with a group of preset indoor throttle opening lower limit value sets corresponding to each sub-state, and the magnitude relation of the indoor throttle opening lower limit values corresponding to the three sub-states is as follows in sequence from big to small: a second sub-state, a first sub-state, and a third sub-state;
the heating operation mode is respectively provided with a preset lower limit value of the outdoor throttle opening corresponding to each sub-state, and the magnitude relation of the lower limit values of the outdoor throttle opening corresponding to the three sub-states is as follows in sequence from big to small: a second sub-state, a first sub-state, and a third sub-state.
6. The multi-split system according to claim 5, further comprising performing an inter-sub-state transition determination when the operation state is a steady operation state, and determining that the current operation state is to be transitioned from the current sub-state to another sub-state when an inter-sub-state transition condition is satisfied.
7. The multi-split system of claim 6, wherein the method for determining the transition between sub-states in the cooling operation mode comprises:
acquiring the current exhaust temperature and low pressure, and judging to migrate from the current sub-state to the second sub-state when the exhaust temperature exceeds a set first temperature limit value or the low pressure is lower than a set first pressure limit value;
if the current state is the second sub-state and the exhaust temperature is lower than the set second temperature limit value and the low pressure exceeds the set second pressure limit value, judging that the current state is shifted to the first sub-state from the second sub-state;
if the current state is the first sub-state, and the exhaust temperature is lower than the set third temperature limit value and the duration reaches the first time limit value, judging that the current state is shifted to the third sub-state from the current first sub-state;
the method for judging the migration between sub-states in the heating operation mode comprises the following steps:
acquiring the current exhaust temperature and low pressure, and judging to migrate from the current sub-state to the second sub-state when the exhaust temperature exceeds a set fourth temperature limit value or the low pressure is lower than a set fourth pressure limit value;
if the current state is the second sub-state and the exhaust temperature is lower than the set fourth temperature limit value and the low pressure exceeds the set second pressure limit value, judging that the current state is shifted to the first sub-state from the second sub-state;
and if the current state is the first sub-state, and the exhaust temperature is lower than the set sixth temperature limit value and the duration reaches the second time limit value, judging that the current state is shifted to the third sub-state from the first sub-state.
8. The multi-split system of claim 4 or 7, wherein the low pressure is obtained from a suction saturation temperature look-up table comprising:
when the operation mode is a refrigeration operation mode, the air suction saturation temperature X=T1l+K1, wherein T11 is the indoor unit liquid pipe temperature, and K1 is the compensation coefficient in the refrigeration operation mode;
when the operation mode is a heating operation mode, the suction saturation temperature x=tli2+k1, wherein T12 is the outdoor unit heat exchanger temperature, and K2 is the compensation coefficient in the heating operation mode.
9. The multi-split system of claim 5, wherein the current operating state is determined to transition from the transitional operating state to the first sub-state when the inter-state transition condition is satisfied.
10. The multi-split system of claim 5, wherein the current operating state transitions to a transitional operating state when the compressor is shut down and restarted.
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