CN112229086A - Air conditioner - Google Patents
Air conditioner Download PDFInfo
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- CN112229086A CN112229086A CN202011090755.7A CN202011090755A CN112229086A CN 112229086 A CN112229086 A CN 112229086A CN 202011090755 A CN202011090755 A CN 202011090755A CN 112229086 A CN112229086 A CN 112229086A
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- Prior art keywords
- expansion valve
- electronic expansion
- compressor
- exhaust superheat
- air conditioner
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B13/00—Compression machines, plants or systems, with reversible cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
- F25B2313/02741—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using one four-way valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/19—Pumping down refrigerant from one part of the cycle to another part of the cycle, e.g. when the cycle is changed from cooling to heating, or before a defrost cycle is started
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2513—Expansion valves
Abstract
The invention discloses an air conditioner, comprising: the plate heat exchanger comprises a first heat exchange channel and a second heat exchange channel, wherein a second port of the first heat exchange channel is communicated with the air supplementing port of the air supplementing cavity, and a second port of the second heat exchange channel is communicated with one end of the outdoor heat exchanger; an electronic expansion valve disposed on a channel between a first port of the first heat exchange channel and a second port of the second heat exchange channel; a controller configured to perform: when the compressor is started for a plurality of times and the electronic expansion valve is opened, determining sampling time T according to the exhaust superheat deviation E (n) of the compressor; and calculating a time variation differential value DE (n) of the exhaust superheat degree deviation E (n) at the current sampling time; and (3) controlling and adjusting the opening degree of the electronic expansion valve according to E (n) and DE (n) at the current sampling time. The invention realizes the fine adjustment of the electronic expansion valve, accurately controls the air supplement amount returned to the compressor and ensures the performance and the working reliability of the compressor.
Description
Technical Field
The invention relates to the technical field of air conditioners, in particular to an air conditioner with an electronic expansion valve for supplementing air and increasing enthalpy.
Background
Fig. 1 is a schematic diagram of a conventional vapor-supplementing enthalpy-increasing refrigerant cycle system.
As shown in fig. 1, the conventional air-supply enthalpy-increasing refrigeration cycle system includes a compressor 11, an outdoor heat exchanger 12, a plate heat exchanger 13, an electronic expansion valve 14 for supplying air and increasing enthalpy, and an indoor heat exchanger 15, wherein the compressor 11 includes an intermediate cavity a and an air-supply cavity b, the plate heat exchanger 13 includes a first heat exchange passage T2 and a second heat exchange passage T1, the compressor 11, the outdoor heat exchanger 12, the second heat exchange passage T1 of the plate heat exchanger 13, and the indoor heat exchanger 15 constitute a main refrigerant cycle loop, a second port a2 of a first heat exchange passage T2 of the plate heat exchanger 13 is communicated with an air-supply port of the intermediate cavity of the compressor 11, and the electronic expansion valve 14 is disposed on a passage between a second port b2 of a second heat exchange passage T1 of the plate heat exchanger 13 and a first port a1 of the first heat exchange passage T2.
Specifically, during heating, after the refrigerant is cooled through the second heat exchange channel T1 of the plate heat exchanger 13, the refrigerant is divided into two paths, one path of the refrigerant directly flows into the outdoor heat exchanger for heat exchange, and the other path of the refrigerant is throttled and reduced in pressure through the electronic expansion valve 14, then returns to the first heat exchange channel T2 of the plate heat exchanger for cooling, and then is conveyed to the air supplement port of the intermediate cavity a of the compressor 11, so that enthalpy difference is increased, and capacity and energy efficiency are improved.
In the north low-temperature heating system, low-temperature enthalpy-increasing heat pump products are adopted, the emphasis of enthalpy-increasing loops of the products lies in the control of the quantity of circulating refrigerants, and the air supplement quantity of the return compressor 11 determines the sub-collection performance and reliability, so the air supplement quantity of the return compressor 11 needs to be controlled.
In the use process of the existing air-supply enthalpy-increasing refrigerant circulating system, some air-supply superheat degrees are used for controlling, the opening degree of the electronic expansion valve 14 is controlled according to the size of the air-supply superheat degree, but the air-supply superheat degree is unstable at low temperature, so that the electronic expansion valve 14 is easy to fluctuate too much due to the control, and the possibility of liquid return is caused; some control is carried out by monitoring the exhaust superheat degree at the outlet of the compressor, and the opening degree of the electronic expansion valve 14 is controlled according to the deviation between the exhaust superheat degree and the current exhaust superheat degree, so that the regulation is not fine, and the fluctuation range is large.
Disclosure of Invention
The embodiment of the invention provides an air conditioner, which is used for carrying out PID control on an electronic expansion valve, realizing fine adjustment of the electronic expansion valve, accurately controlling the air supplement amount returned to a compressor and ensuring the performance and the working reliability of the compressor.
In order to realize the purpose of the invention, the invention is realized by adopting the following technical scheme:
the present application relates to an air conditioner, which includes:
a compressor having a middle chamber and a gas replenishing chamber;
the plate heat exchanger comprises a first heat exchange channel and a second heat exchange channel, a second port of the first heat exchange channel is communicated with the air supplementing port of the air supplementing cavity, and a second port of the second heat exchange channel is communicated with one end of the outdoor heat exchanger;
the electronic expansion valve is used for replenishing air to the air replenishing cavity and is arranged on a channel between a first port of the first heat exchange channel and a second port of the second heat exchange channel;
characterized in that, the air conditioner still includes:
a controller configured to perform the following operations:
when the compressor is started for a plurality of times and the electronic expansion valve is opened, determining sampling time T according to the discharge superheat deviation E (n) of the compressor;
and calculating a time-varying differential value DE (n) = (E (n) -E (n-1))/T of the exhaust superheat deviation E (n) at the current sampling time, wherein E (n-1) is E (n) of the last sampling;
and adjusting the opening degree of the electronic expansion valve according to the control of E (n) and DE (n) at the current sampling time.
The air conditioner determines the sampling time according to E (n), utilizes E (n) and DE (n) to comprehensively carry out PID (proportion integration differentiation) adjustment on the opening degree of the electronic expansion valve, has fine adjustment, avoids larger fluctuation of the exhaust superheat degree of the compressor, improves the performance of the compressor, and has high working reliability.
In this application, the controller calculates the discharge superheat deviation e (n) of the compressor, specifically:
setting an upper limit value SPH and a lower limit value SPL of a target exhaust superheat degree of the compressor, and dividing the target exhaust superheat degree into three sections by using the upper limit value SPH and the lower limit value SPL: a first interval (- ∞, SPL), a second interval [ SPL, SPH ], and a third interval (SPH, + ∞);
and calculating the exhaust superheat deviation E (n) according to the section where the actual exhaust superheat of the compressor is located and the target exhaust superheat in the section.
In this application, the controller determines the sampling time T according to the discharge superheat deviation e (n) of the compressor, specifically:
when the actual exhaust superheat degree is in the first interval, determining sampling time T as a first time period;
when the actual exhaust superheat degree is in the second interval, determining sampling time T as a second time period;
when the actual exhaust superheat degree is in the third interval, determining sampling time T as a third time period;
wherein the second time period is greater than the first time period and the third time period, respectively.
In the present application, the controller sets the exhaust superheat deviation e (n) to zero when the actual exhaust superheat is in the second interval.
In the application, the controller increases the opening of the electronic expansion valve as E (n) becomes larger when the exhaust superheat deviation E (n) > 0 and decreases the opening of the electronic expansion valve as E (n) becomes smaller when the exhaust superheat deviation E (n) < 0 at the current sampling time;
the controller increases the electronic expansion valve opening as DE (n) becomes larger at the time of the time-varying differential value DE (n) > 0 at the current sampling time, and decreases the electronic expansion valve opening as DE (n) becomes smaller at the time of the exhaust superheat deviation DE (n) < 0.
In the present application, the controller increases the electronic expansion valve opening adjustment by a small number of steps when e (n) is large and the amount of change is small, and increases the electronic expansion valve opening adjustment by a large number of steps when e (n) is large and the amount of change is large;
when E (n) < 0, the number of steps for decreasing the opening degree adjustment of the electronic expansion valve is small when E (n) is small and the amount of change is small, and the number of steps for decreasing the opening degree adjustment of the electronic expansion valve is large when E (n) is small and the amount of change is large;
when DE (n) is greater than 0, the controller increases the opening degree of the electronic expansion valve by a small number of steps when DE (n) is greater and the variation amount is smaller, and increases the opening degree of the electronic expansion valve by a large number of steps when DE (n) is greater and the variation amount is larger;
when de (n) < 0, the number of steps by which the electronic expansion valve opening degree adjustment is reduced is small when de (n) is small and the amount of change is small, and the number of steps by which the electronic expansion valve opening degree adjustment is small is large when de (n) is small and the amount of change is large.
In this application, the controller controls the electronic expansion valve to have a lower opening limit value according to an actual operating frequency of the compressor.
In the present application, the controller resets the discharge superheat deviation e (n) when the compressor is stopped.
In this application, the condition for controlling the electronic expansion valve to open by the controller at least comprises the following conditions:
(a) the compressor operates for a number of times;
(b) the actual running frequency f of the compressor is more than or equal to a preset frequency value;
(c) the suction pressure PSL of the compressor is less than a preset pressure value.
In this application, the condition under which the controller controls to close the electronic expansion valve includes at least one of:
(a') the compressor is shut down;
(b') the actual operating frequency f of said compressor < a preset frequency value;
(c') the suction pressure PSL of the compressor is more than or equal to a preset pressure value;
(d') the air conditioner is in a defrosting mode.
Other features and advantages of the present invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of a prior art vapor-augmented refrigerant cycle system.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. In the description of the present invention, it is to 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 those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
In the description of the present invention, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected unless otherwise explicitly stated or limited. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. In the foregoing description of embodiments, the 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 "first" 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 defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
[ basic operation principle of air conditioner ]
A refrigeration cycle of an air conditioner includes a compressor, a condenser, an expansion valve, and an evaporator. The refrigeration cycle includes a series of processes involving compression, condensation, expansion, and evaporation, and supplies refrigerant to the air that has been conditioned and heat-exchanged.
The compressor compresses a refrigerant gas in a high-temperature and high-pressure state and discharges the compressed refrigerant gas. 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 expansion valve expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator can achieve a cooling effect by heat-exchanging with a material to be cooled using latent heat of evaporation of a refrigerant. The air conditioner can adjust the temperature of the indoor space throughout the cycle.
The outdoor unit of the air conditioner refers to a portion including a compressor of a refrigeration cycle and includes an outdoor heat exchanger, the indoor unit of the air conditioner includes an indoor heat exchanger, and an expansion valve may be provided in the indoor unit or the outdoor unit of the air conditioner.
The indoor heat exchanger and the outdoor heat exchanger serve as a condenser or an evaporator. The air conditioner is used as a heater in a heating mode when the indoor heat exchanger is used as a condenser, and as a cooler in a cooling mode when the indoor heat exchanger is used as an evaporator.
[ air-conditioner ]
In the present application, the compressor 11 is a compressor having a function of supplementing air and increasing enthalpy. And referring to fig. 1, the compressor 11 includes an intermediate chamber a and a suction chamber b.
The suction chamber b of the compressor 11 compresses the entering refrigerant to ensure the refrigerant circulation; the intermediate chamber b of the compressor 11 performs heat exchange after the refrigerant is sucked, so as to reduce the temperature of the compressor 11, thereby ensuring the operational reliability of the compressor 11.
The plate heat exchanger 13 comprises a first heat exchanging channel T2 and a second heat exchanging channel T1, wherein the first heat exchanging channel T2 comprises a first port a1 and a second port a2, and the second heat exchanging channel T1 comprises a first port b1 and a second port b 2.
The compressor 11, the outdoor heat exchanger 12, the second heat exchange passage T1 of the plate heat exchanger 13 and the indoor heat exchanger 15 constitute a refrigerant main circulation circuit.
The second port b2 of the second heat exchanging passage T1 of the plate heat exchanger 13 communicates with one end of the outdoor heat exchanger 12, and the first port b1 of the second heat exchanging passage T1 communicates with one end of the indoor heat exchanger 15.
The electronic expansion valve 14 is disposed on a passage between the second port b2 of the second heat exchange passage T1 of the plate heat exchanger 13 and the first port a1 of the first heat exchange passage T2, and is configured to adjust an amount of air supplement returned to the compressor 11 by adjusting an opening degree thereof, so as to achieve enthalpy increase.
The second port a2 of the first heat exchange passage T2 of the plate heat exchanger 13 communicates with the supplementary air port of the intermediate chamber a of the compressor 11.
In addition to controlling the air conditioner to perform a heating/cooling cycle, the controller (not shown) may be configured to control and adjust the opening degree of the electronic expansion valve 14 to adjust the amount of air supplement returned to the air supplement port of the intermediate chamber a of the compressor 11.
[ operation mode of air conditioner ]
When the air conditioner is in a heating cycle, refrigerant sprayed from the compressor 11 enters the indoor heat exchanger 15 through the four-way valve (at the moment, the four-way valve is powered on), after heat exchange is performed in the indoor heat exchanger 15, the refrigerant is cooled through the second heat exchange channel T1 of the plate heat exchanger 13, the refrigerant is divided into two paths, one path enters the outdoor heat exchanger 12 for heat exchange, then is conveyed to the compressor 11 for compression, and the other path is throttled and depressurized through the electronic expansion valve 24, then flows back to the first heat exchange channel T2 of the plate heat exchanger 13 for cooling, and then is output to the air supplement port of the middle cavity a of the compressor 11 through the second port a2 of the first heat exchange channel T63.
The refrigerant flow path in the heating cycle is shown by a broken line in fig. 1.
When the air conditioner is in a refrigeration cycle, refrigerant sprayed from the compressor 11 enters the outdoor heat exchanger 12 through the four-way valve (at the moment, the four-way valve is powered off), after heat exchange is performed in the outdoor heat exchanger 12, the refrigerant is divided into two paths, one path of refrigerant is output from the first port b1 to the indoor heat exchanger 15 for heat exchange through the second heat exchange channel T1 of the plate heat exchanger 13, finally, the refrigerant returns to the compressor 11 through the four-way valve, and after throttling and pressure reduction through the electronic expansion valve 14, the other path of refrigerant returns to the first heat exchange channel T2 of the plate heat exchanger 13 for cooling and then is output to the air supplement port of the middle cavity a of the compressor 11 through.
The refrigerant flow path in the refrigeration cycle is shown by a solid line in fig. 1.
[ opening degree control of electronic expansion valve ]
The controller comprehensively controls and adjusts the opening degree of the electronic expansion valve 14 according to the current exhaust superheat deviation E (n) of the electronic expansion valve 14 and the time change derivative DE (n) of the exhaust superheat deviation E (n).
Wherein de (n) = E (n) -E (n-1).
The control of the opening degree of the electronic expansion valve 14 mainly involves determining the deviation e (n) of the degree of superheat of the exhaust gas, determining the sampling time T, and determining the time-varying derivative de (n) of the deviation.
Open and closed conditions of electronic expansion valve
In the present application, the conditions for opening the electronic expansion valve 14 include at least the following conditions: a. the compressor 11 is operated for a number of times (e.g. 5 minutes); b. the actual running frequency f of the compressor 11 is more than or equal to the preset frequency; c. the suction pressure PSL of the compressor 11 is smaller than a preset pressure value.
In the present application, the condition that the electronic expansion valve 14 is closed (i.e., the opening degree is 0pls (i.e., the number of steps)) includes at least one of the following: a', the compressor 11 is stopped (for example, by remote controller operation stop, thermostat power off, abnormal stop, etc.); b', the actual running frequency f of the compressor 11 is less than the preset frequency; c', the suction pressure PSL of the compressor 11 is more than or equal to a preset pressure value; d', the air conditioner is in a defrost mode.
In the present application, the predetermined frequency is set to 40Hz and the predetermined pressure value is set to 0.56 MPa.
Allowable lower limit of opening of electronic expansion valve
The compressor 11 is first powered on to operate at an operating frequency f of 40Hz for three minutes, and the initial opening of the electronic expansion valve 14 is 32 pls.
Thereafter, if the actual operating frequency f of the compressor 11 decreases, the opening degree of the electronic expansion valve 14 is controlled to allow the decrease to 0 pls; when the actual operating frequency f of the compressor 11 increases, the opening degree of the electronic expansion valve 14 is controlled to allow the down-regulation to 32 pls.
Determining the exhaust superheat deviation E (n)
The actual discharge superheat Td of the compressor 11 is calculated when the compressor 11 is on for a number of times (e.g., 5 minutes) and the electronic expansion valve 14 is open.
The actual discharge superheat Td of the compressor 11 is equal To the difference between the discharge pipe temperature Te and the high pressure saturation temperature To.
The exhaust pipe temperature Te and the high pressure saturation temperature To can be obtained by the means of the prior art, and are not described herein.
In order to accurately calculate the exhaust superheat deviation e (n), the controller sets an upper limit value SPH and a lower limit value SPL of a target exhaust superheat of the compressor 11, and divides the target exhaust superheat so as to be able to calculate the exhaust superheat deviation e (n) in a targeted manner.
Dividing the target exhaust superheat degree into three sections according to the upper limit value SPH and the lower limit value SPL of the target exhaust superheat degree: a first interval (- ∞, SPL), a second interval [ SPL, SPH ], and a third interval (SPH, + ∞).
For example, the target degree of superheat of exhaust gas in the first section is set to SPL 1; the target degree of superheat of the exhaust gas in the second section is set to SPLH, and the target degree of superheat of the exhaust gas in the third section is set to SPH 1.
The exhaust superheat deviation e (n) is calculated from the sections (i.e., the first section, the second section, and the third section) in which the calculated actual exhaust superheat Td is located, and the target exhaust superheat in the sections (i.e., the SPL1 corresponding to the first section, the SPLH corresponding to the second section, and the SPH1 corresponding to the third section).
In the present application, when the actual exhaust superheat degree Td is in the first section, the exhaust superheat degree deviation e (n) = Td-SPL1 is calculated; when the actual exhaust superheat degree Td is in the second interval, the fluctuation of the exhaust superheat degree deviation e (n) is small, so the controller sets the exhaust superheat degree deviation e (n) = 0; when the actual exhaust superheat degree Td is in the third section, the exhaust superheat degree deviation e (n) = Td-SPH1 is calculated.
Determining a sampling time T
The sampling time T is determined according to the exhaust superheat deviation E (n), namely, the sampling time T is determined according to the sections (namely, the first section, the second section and the third section) of the target exhaust superheat, where the calculated actual exhaust superheat Td is located.
When the actual exhaust superheat Td is in the first section, the sampling time T is determined to be the first period T1.
When the actual exhaust superheat Td is in the second section, the sampling time T is determined to be the second period T2.
When the actual exhaust superheat Td is in the third section, the sampling time T is determined to be the third period T3.
In the present application, since the exhaust superheat deviation e (n) =0 is set when the actual exhaust superheat Td is in the second interval, the sampling time T can be appropriately extended when the actual exhaust superheat Td is in the second interval, that is, T2 is greater than T1 and T3, respectively.
The sampling time T is an operation period for adjusting the opening degree of the electronic expansion valve 14, and for example, the sampling time T =20 seconds means that the opening degree of the electronic expansion valve 14 is controlled and adjusted when the current time passes 20 seconds, and the opening degree of the electronic expansion valve 14 is controlled and adjusted when the current time passes 20 seconds, so that the operation is repeated until the compressor 11 is stopped.
In the present application, T1= T3=20 seconds, T2=120 seconds are selected. Of course, other values for T1, T2, and T3 may be selected.
For example, when the actual exhaust superheat degree Td is in the first interval, the opening degree of the electronic expansion valve 14 is controlled and adjusted according to e (n) and de (n) in the first interval, after 20 seconds of the current time, if the actual exhaust superheat degree Td is still in the first interval, the opening degree of the electronic expansion valve 14 is controlled and adjusted according to e (n) and de (n) in the first interval, after 20 seconds, if the actual exhaust superheat degree Td is in the second interval, the interval where the actual exhaust superheat degree Td is located is continuously monitored for 20 seconds, if 120 seconds are both in the second interval, the opening degree of the electronic expansion valve 14 is controlled and adjusted according to e (n) and de (n) in the second interval, if 20 seconds are passed, the actual exhaust superheat degree Td is in the third interval, the opening degree of the electronic expansion valve 14 is controlled and adjusted according to e (n) and de (n) in the third interval, thereafter, the actual discharge superheat Td is monitored continuously until the compressor 11 is stopped.
When e (n) > 0, it indicates that the actual exhaust superheat Td is higher than the target exhaust superheat (i.e., SPL1 or SPH 1), and at this time, the opening degree of the electronic expansion valve 14 needs to be controlled in the opening direction.
When the discharge superheat deviation e (n) > 0 is detected at the current sampling time T, the opening degree of the electronic expansion valve 14 is increased as e (n) increases.
That is, when e (n) is large and the amount of change is small, the number of steps by which the opening degree of the electronic expansion valve 14 is adjusted to be large is small, and when e (n) is large and the amount of change is large, the number of steps by which the opening degree of the electronic expansion valve 14 is adjusted to be large is large, see the data in table 1.
When e (n) < 0, it indicates that the actual exhaust superheat Td is lower than the target exhaust superheat (i.e., SPL1 or SPH 1), and at this time, the opening degree of the electronic expansion valve 14 needs to be controlled in the closing direction.
When the gas superheat deviation e (n) < 0 at the current sampling time T, the opening degree of the electronic expansion valve 14 is decreased as e (n) decreases.
That is, when e (n) is small and the amount of change is small, the number of steps for decreasing the opening degree adjustment of the electronic expansion valve 14 is small, and when e (n) is small and the amount of change is large, the number of steps for decreasing the opening degree adjustment of the electronic expansion valve 14 is large, see the data in table 1.
Determining the time-varying derivative DE (n)
The time-varying derivative DE (n) is the ratio of the deviation of the exhaust superheat E (n) to the sampling time T, i.e., DE (n) = (E (n) -E (n-1))/T, where E (n) is the exhaust superheat deviation at the current sampling time and E (n-1) is the exhaust superheat deviation at the last sampling time.
When de (n) > 0 indicates that the actual exhaust superheat Td is increasing, the opening degree of the electronic expansion valve 14 needs to be controlled in the opening direction.
At the current sampling time, when the time-varying differential value DE (n) > 0, the electronic expansion valve opening degree is increased as DE (n) becomes larger.
That is, when de (n) > 0, the number of steps by which the opening degree adjustment of the electronic expansion valve 14 is increased is small when de (n) is large and the amount of change is small, and is large when de (n) is large and the amount of change is large, see the data in table 1.
When de (n) < 0, this means that the actual exhaust superheat Td is decreasing, and at this time, the opening degree of the electronic expansion valve 14 needs to be controlled in the closing direction.
At the present sampling time, when the exhaust superheat deviation de (n) < 0, the opening degree of the electronic expansion valve 14 is decreased as de (n) becomes smaller.
That is, when de (n) < 0, the number of steps in which the opening degree adjustment of the electronic expansion valve 14 is reduced is small when de (n) is small and the amount of change is small, and the number of steps in which the opening degree adjustment of the electronic expansion valve 14 is small is large when de (n) is small and the amount of change is large, see the data in table 1.
The opening degree of the electronic expansion valve 14 is controlled comprehensively based on the exhaust superheat deviation e (n) and the time variation derivative de (n) obtained as described above, and the number of opening degree control steps of the electronic expansion valve 14 is schematically shown in table 1 below.
Where the data in table 1, for example, a positive number indicates a number of steps added to the current opening degree of the electronic expansion valve 14, for example, a negative number indicates a number of steps subtracted to the current opening degree of the electronic expansion valve 14, and data 0 indicates that the number of steps of the electronic expansion valve 14 is adjusted to zero, according to the differences e (n) and de (n).
For example, when 10 < E (n) and-2 ≦ DE (n) < 2, the current opening degree of the electronic expansion valve 14 is increased by the step number 4; when E (n) is more than 10 and less than or equal to DE (n) and less than or equal to 2, the current opening degree of the electronic expansion valve 14 is increased by 4 steps; when E (n) is less than or equal to 5 and DE (n) is less than-5, reducing the current opening of the electronic expansion valve 14 by 2 steps; when E is more than or equal to-2 and less than or equal to (n) and DE is more than or equal to-5 and less than or equal to (n) 2, the current opening degree of the electronic expansion valve 14 is reduced by 1 step.
The air conditioner of the embodiment comprehensively performs PID adjustment on the opening degree of the electronic expansion valve 14 according to the exhaust superheat degree deviation E (n) and the time variation derivative DE (n) of the exhaust superheat degree deviation, so that the step number of the adjustment on the opening degree of the electronic expansion valve 14 is finer, the large fluctuation of the exhaust superheat degree of the compressor is avoided, the performance of the compressor is improved, liquid return through the electronic expansion valve 14 is avoided, and the working reliability of the whole air conditioner system is improved.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions.
Claims (10)
1. An air conditioner, comprising:
a compressor having a middle chamber and a gas replenishing chamber;
the plate heat exchanger comprises a first heat exchange channel and a second heat exchange channel, a second port of the first heat exchange channel is communicated with the air supplementing port of the air supplementing cavity, and a second port of the second heat exchange channel is communicated with one end of the outdoor heat exchanger;
the electronic expansion valve is used for replenishing air to the air replenishing cavity and is arranged on a channel between a first port of the first heat exchange channel and a second port of the second heat exchange channel;
characterized in that, the air conditioner still includes:
a controller configured to perform the following operations:
when the compressor is started for a plurality of times and the electronic expansion valve is opened, determining sampling time T according to the discharge superheat deviation E (n) of the compressor;
and calculating a time-varying differential value DE (n) = (E (n) -E (n-1))/T of the exhaust superheat deviation E (n) at the current sampling time, wherein E (n-1) is E (n) of the last sampling;
and adjusting the opening degree of the electronic expansion valve according to the control of E (n) and DE (n) at the current sampling time.
2. The air conditioner according to claim 1, wherein the controller calculates a discharge superheat deviation e (n) of the compressor, specifically:
setting an upper limit value SPH and a lower limit value SPL of a target exhaust superheat degree of the compressor, and dividing the target exhaust superheat degree into three sections by using the upper limit value SPH and the lower limit value SPL: a first interval (- ∞, SPL), a second interval [ SPL, SPH ], and a third interval (SPH, + ∞);
and calculating the exhaust superheat deviation E (n) according to the section where the actual exhaust superheat of the compressor is located and the target exhaust superheat in the section.
3. The air conditioner according to claim 2, wherein the controller determines a sampling time T according to a discharge superheat deviation e (n) of the compressor, specifically:
when the actual exhaust superheat degree is in the first interval, determining sampling time T as a first time period;
when the actual exhaust superheat degree is in the second interval, determining sampling time T as a second time period;
when the actual exhaust superheat degree is in the third interval, determining sampling time T as a third time period;
wherein the second time period is greater than the first time period and the third time period, respectively.
4. The air conditioner according to claim 2 or 3,
when the actual exhaust superheat is in the second interval, the controller sets the exhaust superheat deviation e (n) to zero.
5. The air conditioner according to any one of claims 1 to 3,
the controller increases the opening of the electronic expansion valve as E (n) becomes larger when the exhaust superheat deviation E (n) is larger than 0 and decreases the opening of the electronic expansion valve as E (n) becomes smaller when the exhaust superheat deviation E (n) is smaller than 0 at the current sampling time;
the controller increases the electronic expansion valve opening as DE (n) becomes larger at the time of the time-varying differential value DE (n) > 0 at the current sampling time, and decreases the electronic expansion valve opening as DE (n) becomes smaller at the time of the exhaust superheat deviation DE (n) < 0.
6. The air conditioner according to claim 5,
when E (n) is greater than 0, the controller increases the opening degree of the electronic expansion valve by a small number of steps when E (n) is greater and the variation amount is smaller, and increases the opening degree of the electronic expansion valve by a large number of steps when E (n) is greater and the variation amount is larger;
when E (n) < 0, the number of steps for decreasing the opening degree adjustment of the electronic expansion valve is small when E (n) is small and the amount of change is small, and the number of steps for decreasing the opening degree adjustment of the electronic expansion valve is large when E (n) is small and the amount of change is large;
when DE (n) is greater than 0, the controller increases the opening degree of the electronic expansion valve by a small number of steps when DE (n) is greater and the variation amount is smaller, and increases the opening degree of the electronic expansion valve by a large number of steps when DE (n) is greater and the variation amount is larger;
when de (n) < 0, the number of steps by which the electronic expansion valve opening degree adjustment is reduced is small when de (n) is small and the amount of change is small, and the number of steps by which the electronic expansion valve opening degree adjustment is small is large when de (n) is small and the amount of change is large.
7. The air conditioner according to claim 6, wherein the controller controls the electronic expansion valve to have a lower limit value of the opening degree according to an actual operation frequency of the compressor.
8. The air conditioner according to any one of claims 1 to 3,
the controller resets the discharge superheat deviation e (n) when the compressor is stopped.
9. The air conditioner according to any one of claims 1 to 3,
the condition that the controller controls to open the electronic expansion valve at least comprises the following conditions:
(a) the compressor operates for a number of times;
(b) the actual running frequency f of the compressor is more than or equal to a preset frequency value;
(c) the suction pressure PSL of the compressor is less than a preset pressure value.
10. The air conditioner according to any one of claims 1 to 3, 9,
the conditions under which the controller controls the electronic expansion valve to be closed include at least one of:
(a') the compressor is shut down;
(b') the actual operating frequency f of said compressor < a preset frequency value;
(c') the suction pressure PSL of the compressor is more than or equal to a preset pressure value;
(d') the air conditioner is in a defrosting mode.
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| CN202011090755.7A CN112229086A (en) | 2020-10-13 | 2020-10-13 | Air conditioner |
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