CN112444000A

CN112444000A - Air conditioner

Info

Publication number: CN112444000A
Application number: CN202011371782.1A
Authority: CN
Inventors: 高永坤; 张恒; 夏兴祥; 赵玉垒
Original assignee: Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Current assignee: Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Priority date: 2020-11-30
Filing date: 2020-11-30
Publication date: 2021-03-05

Abstract

The invention discloses an air conditioner, comprising: at least one indoor unit; at least one outdoor unit module, each outdoor unit module includes: a compressor; a flow path switching device for switching a flow path of the refrigerant discharged from the compressor; a defrost throttling device for throttling a portion of the refrigerant from the compressor; the air side valve is connected with the defrosting throttling device in parallel; a plurality of outdoor heat exchangers arranged in parallel; the defrosting switching devices correspond to the outdoor heat exchangers respectively and are used for switching the outdoor heat exchangers to be communicated with the defrosting throttling devices or communicated with the gas-liquid separator; a plurality of second liquid pipe throttling devices which are respectively connected with the outdoor heat exchanger and the gas-liquid separator; the control device alternately defrosts the outdoor heat exchangers to be defrosted. The invention realizes that the air conditioner continuously heats and simultaneously controls the pressure and defrosts the defrosting heat exchanger, improves the defrosting efficiency, ensures the capacity of the indoor unit to be maximized, and improves the indoor thermal comfort.

Description

Air conditioner

Technical Field

The invention relates to the technical field of air conditioners, in particular to an air conditioner.

Background

The technology of the air source heat pump multi-split air conditioner is mature day by day, and the air source heat pump multi-split air conditioner is widely applied to the fields of household and business. The air source heat pump multi-split air conditioner comprises at least one indoor unit and at least one outdoor unit module, wherein when the number of the indoor units is two or more, the indoor units are arranged in parallel, each indoor unit is provided with an indoor heat exchanger and a corresponding indoor fan, when the number of the outdoor unit modules is two or more, the outdoor unit modules are arranged in parallel, each outdoor unit module is provided with a variable frequency compressor, a four-way valve, a throttling element, at least one outdoor heat exchanger and an outdoor fan, which are communicated through a connecting pipeline, and when the number of the outdoor heat exchangers is at least two, the outdoor heat exchangers are arranged in parallel.

The air source heat pump has a big problem in heating operation: when outdoor temperature and humidity reach certain conditions, outdoor heat exchanger air side can frost, and along with the increase of the volume of frosting, the evaporimeter surface can be blockked up gradually, leads to outdoor heat exchanger surface heat transfer coefficient to reduce, and the gas flow resistance increases, seriously influences the machine effect of heating, consequently, the unit needs regularly to defrost.

At present, a reverse defrosting mode is mostly adopted, the outdoor unit is switched into a condenser through the electrification reversing of a four-way valve, the defrosting is carried out by utilizing the sensible heat and the latent heat of condensation of a high-temperature and high-pressure refrigerant, the defrosting speed is high, and the reliability is good. However, the heating operation is stopped during defrosting, and meanwhile, heat is absorbed from the indoor space due to the fact that the indoor heat exchanger is switched to the evaporator, the indoor temperature is obviously reduced, and indoor thermal comfort is seriously affected.

In order to solve the problems, hot gas bypass defrosting is arranged, namely, the exhaust gas of a compressor is led into an outdoor heat exchanger to be defrosted by using a bypass branch to defrost under the condition that the flow direction of a system refrigerant is not changed.

This defrosting mode has the following disadvantages: 1. the heat converted by the power consumption of the compressor is utilized for defrosting, which belongs to low-pressure defrosting, and the heat is less and the defrosting time is long; 2. when the hot gas bypass defrosting is carried out, low-pressure sensible heat is utilized for defrosting, the temperature is lower, the heat exchange temperature difference with a frost layer is small, and the defrosting reliability is poor; 3. although the flow direction of the refrigerant is not changed during defrosting, the flow rate of the refrigerant of the indoor unit is very small, the system does not supply heat to the indoor unit, the indoor temperature is reduced during defrosting, and the user comfort is poor.

Disclosure of Invention

The embodiment of the invention provides an air conditioner, which can realize continuous heating of the air conditioner and pressure-controlled defrosting of a defrosting heat exchanger at the same time, improve defrosting efficiency, ensure the maximization of indoor unit capacity and improve indoor thermal comfort.

In order to realize the purpose of the invention, the invention is realized by adopting the following technical scheme:

the application relates to an air conditioner, its characterized in that includes:

at least one indoor unit;

at least one outdoor unit module, each outdoor unit module includes:

a compressor;

a flow path switching device for switching a flow path of the refrigerant discharged from the compressor;

a defrost throttle for throttling a portion of refrigerant from the compressor;

an air side valve connected in parallel with the defrost throttling device;

a plurality of outdoor heat exchangers arranged in parallel;

the defrosting switching devices correspond to the outdoor heat exchangers respectively and are used for switching the outdoor heat exchangers to be communicated with the defrosting throttling devices or communicated with the gas-liquid separator;

a plurality of first liquid pipe throttling devices which are respectively connected with the indoor unit and the outdoor heat exchangers;

a plurality of second liquid pipe throttling devices which are respectively connected with the outdoor heat exchanger and the gas-liquid separator;

the control device controls each flow path switching device, each defrosting throttling device, each air side valve, each defrosting switching device, each first liquid pipe throttling device and each second liquid pipe throttling device when a plurality of outdoor heat exchangers need to be defrosted, and performs alternate defrosting on each outdoor heat exchanger to be defrosted, so that the outdoor heat exchanger to be defrosted is executed as a defrosting heat exchanger, and the rest outdoor heat exchangers are executed as evaporators;

when the defrosting is performed by turns, the control device controls the flow path switching device to be powered on; controlling to open the defrosting throttling device; controlling the defrosting switching device to enable the refrigerant flowing out of the defrosting throttling device to be communicated with a main air pipe of the defrosting heat exchanger; controlling to close a first liquid pipe throttling device and a gas side valve which are communicated with the defrosting heat exchanger; and controlling to open a second liquid pipe throttling device communicated with the defrosting heat exchanger.

Thus, when the air conditioner performs alternate defrosting, the control flow path switching device is opened, the first liquid pipe throttling device and the air side valve are controlled to be cut off, the defrosting throttling device is controlled to be opened, the defrosting switching device is controlled to enable the refrigerant flowing out of the flow throttling device to be communicated with the main air pipe of the defrosting heat exchanger, the second liquid pipe throttling device is controlled to be opened, the defrosting pressure of the defrosting heat exchanger can be controlled, defrosting is achieved by utilizing latent heat of the refrigerant, the defrosting speed is high, the indoor unit keeps certain heating capacity, the air conditioner can continuously heat, and the indoor temperature can quickly rise after defrosting.

In the present application, in defrosting the defrosting heat exchanger, the control device is configured to:

controlling and opening the second liquid pipe throttling device, and controlling and adjusting the opening degree of the second liquid pipe throttling device according to the exhaust superheat degree of the compressor and the target superheat degree range;

and controlling to open the defrosting throttle device, and controlling and adjusting the opening of the defrosting throttle device according to the defrosting pressure and the target defrosting pressure range.

In this application, the second liquid pipe throttling device is controlled to be opened, and the opening degree of the second liquid pipe throttling device is controlled and adjusted according to the exhaust superheat degree of the compressor and the target superheat degree range, specifically:

setting a target exhaust superheat range of the compressor;

calculating the discharge superheat degree of the compressor;

and comparing whether the exhaust superheat degree is within the target exhaust superheat degree range, if so, keeping the current opening degree of the second liquid pipe throttling device, and if not, adjusting the opening degree of the second liquid pipe throttling device.

In this application, control is opened defrost throttling arrangement, according to defrosting pressure and target defrosting pressure scope, control defrost throttling arrangement's aperture specifically is:

setting a target defrosting pressure range;

calculating the defrosting pressure of the heat exchanger to be defrosted;

and comparing whether the defrosting pressure is in the target defrosting pressure range, if so, keeping the opening degree of the defrosting throttle device, and if not, adjusting the opening degree of the defrosting throttle device.

In this application, adjust the aperture of second liquid pipe throttling arrangement specifically is:

when the exhaust superheat degree is larger than the upper limit value of the target exhaust superheat degree range, increasing the opening degree of the second liquid pipe throttling device;

and when the exhaust superheat degree is smaller than the lower limit value of the target exhaust superheat degree range, reducing the opening degree of the second liquid pipe throttling device.

In this application, adjust defroster's aperture specifically is:

when the defrosting pressure is larger than the upper limit value of the target defrosting pressure range, reducing the opening degree of the defrosting throttle device;

and when the defrosting pressure is smaller than the lower limit value of the target defrosting pressure range, increasing the opening degree of the defrosting throttle device.

In this application, the control device is configured to:

when defrosting the defrosting heat exchanger, if the first preset defrosting time is reached, or

And if the outlet temperature of the defrosting heat exchanger is greater than or equal to a first temperature preset value and is maintained for a certain time period, the defrosting heat exchanger exits the defrosting process and enters a normal heating operation process.

In the present application, the control device is configured to:

the defrosting heat exchanger exits the defrosting process and enters a common heating operation process, and the defrosting heat exchanger specifically comprises the following steps:

controlling to close the defrosting throttling device;

controlling to open the air side valve;

controlling the defrosting switching device to enable the gas side of the defrosting heat exchanger to be communicated with the gas-liquid separator;

controlling to close a second liquid pipe throttling device communicated with the defrosting heat exchanger;

controlling opening of a first tube throttling device communicated with the defrosting heat exchanger.

In this application, the target defrost pressure range is related to the ambient temperature.

In this application, the air conditioner further includes:

a plurality of first switching valves connected in parallel, each corresponding to one indoor unit, for branching at least part of the refrigerant from the compressor switched by the flow path switching device, and corresponding to a gas side of an indoor heat exchanger flowing into the indoor unit;

a plurality of second switching valves connected in parallel, each of which corresponds to one indoor unit, one end of each of the second switching valves being connected to a position where the first switching valve is connected to the gas side of the indoor heat exchanger, and the other end of each of the second switching valves being connected to the gas-liquid separator;

the control device also controls each first switching valve and each second switching valve to enable the air conditioner to have a heat recovery function.

In this application, the outdoor unit module further includes:

the outdoor fans respectively correspond to the outdoor heat exchangers and are connected with the control device, and each outdoor fan and the corresponding outdoor heat exchanger form a wind field;

a separation device for separating adjacent wind farms;

and when the defrosting is performed by turns, the control device controls to close the outdoor fan corresponding to the defrosting heat exchanger.

In the application, when the outdoor heat exchangers exist in each outdoor unit module and are defrosting, the rotating speed of outdoor fans corresponding to the other outdoor heat exchangers which are not defrosting in the outdoor unit module is increased.

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 system structure diagram of an embodiment of an air conditioner according to the present invention;

FIG. 2 is a flow chart of an embodiment of the air conditioner of the present invention during a defrost heat exchanger defrosting when in a rotating defrost mode of operation;

fig. 3 is a system configuration diagram of another embodiment of an air conditioner according to the present invention.

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 an air conditioner refers to a portion including a compressor of a refrigeration cycle and includes an outdoor heat exchanger, the indoor unit of an air conditioner includes an indoor heat exchanger, and an expansion valve may be provided in the indoor unit or the outdoor unit of an air conditioner.

The indoor heat exchanger and the outdoor heat exchanger serve as a condenser or an evaporator. When the indoor heat exchanger is used as a condenser, the air conditioner is used as a heater in a heating mode, and when the indoor heat exchanger is used as an evaporator, the air conditioner is used as a cooler in a cooling mode.

[ air-conditioner ]

In the present application, the outdoor unit module is similar to the air conditioning outdoor unit as described above.

The air conditioner of this application design is many online air conditioners.

The air conditioner includes at least one indoor unit, which are arranged in parallel.

Each indoor unit includes indoor heat exchangers 5-1 and 5-2 (i.e., the indoor heat exchangers as described above) and indoor fans 6-1 and 6-2, respectively, the indoor fans 6-2 and 6-2 serving to blow cold or hot air generated by the indoor heat exchangers 5-1 and 5-2 toward an indoor space, respectively.

Of course, the number of indoor units is not limited to the number described above, and the number of indoor heat exchangers and indoor fans in each indoor unit is not limited to the number described above.

The air conditioner comprises at least one outdoor unit module, and all the outdoor unit modules are arranged in parallel.

For example, there are two outdoor unit modules, denoted as outdoor unit modules a and a ', each outdoor unit module a/a' includes a compressor, a flow path switching device, a defrosting throttle device, an air side valve, a plurality of outdoor heat exchangers arranged in parallel, a plurality of defrosting switching devices corresponding to the respective outdoor heat exchangers, a plurality of first liquid pipe throttle devices, a plurality of outdoor fans, a plurality of second liquid pipe throttle devices, and a gas-liquid separator.

The outdoor unit modules A and A' have the same structure, and the number of the outdoor heat exchangers in each outdoor unit module is at least two.

Referring to fig. 1, there is shown a system configuration diagram of an air conditioner including an outdoor unit module including a compressor 1, a flow path switching device 2, a defrosting throttle device 17, a gas side valve 13, outdoor heat exchangers 11-1 and 11-2 arranged in parallel, two

defrosting switching devices

15 and 16 corresponding to the outdoor heat exchangers 11-1 and 11-2, two first liquid pipe throttle devices 10-1 and 10-2, two outdoor fans 12-1 and 12-2, two second liquid pipe throttle devices 18-1 and 18-2, and a gas-liquid separator 14.

The flow path switching device 2 switches a flow path of the refrigerant discharged from the compressor 1 to the indoor unit or the outdoor heat exchanger. In the present application, the flow path switching device 2 is a four-way valve having four terminals C, D, S and E.

Referring to fig. 1, for the two-pipe multi-split air conditioner, when the flow switching device 2 is powered off, the default is that C is connected with D, S is connected with E, so that the indoor heat exchangers 5-1 and 5-2 are used as evaporators, and the outdoor heat exchangers 11-1 and 11-2 are used as condensers, so that the air conditioner can refrigerate.

When the four-way valve is electrified and reversed, C is connected with S, D is connected with E, so that the indoor heat exchangers 5-1 and 5-2 are used as condensers, the outdoor heat exchangers 11-1 and 11-2 are used as evaporators, and the air conditioner heats.

Referring to fig. 3, for the three-pipe heat recovery multi-split air conditioner, there are divided into a main cooling mode (i.e., the indoor unit has both cooling and heating states, and the cooling load is greater than the heating load, when the outdoor heat exchanger is used as a condenser) and a main heating mode (i.e., the indoor unit has both cooling and heating states, and the heating load is greater than the cooling load, when the outdoor heat exchanger is used as an evaporator).

The operation of the three-pipe heat recovery multi-split air conditioner will be described in detail as follows.

In both the two-pipe heating multi-split air conditioner and the three-pipe heating recovery multi-split air conditioner, there is no difference in the control of each device in the outdoor unit module when defrosting the outdoor heat exchanger 11-1/11-2.

Referring to fig. 1, the number of the outdoor heat exchangers is the same as that of the outdoor fans and corresponds to one another.

The outdoor unit module has an outdoor heat exchanger 11-1/11-2, an outdoor fan 12-1/12-2, a first tube throttling device 10-1/10-2 connecting a tube of the indoor heat exchanger 5-1/5-2 and a tube of the outdoor heat exchanger 11-1/11-2), a defrost throttling device 17, a gas side valve 13, a defrost switching device 15/16, a second tube throttling device 18-1/18-2 connecting a tube of the outdoor heat exchanger 11-1/11-2 and the gas-liquid separator 14.

In the present application, the defrost orifice 17, the first pipe orifice 10-1/10-2, and the second pipe orifice 18-1/18-2 may each be an electronic expansion valve, a two-way thermostatic expansion valve, or the like.

And the defrost switch 15/16 is a four-way valve with four terminals C, D, S and E, C and D connected and S and E connected at default power off, C and S connected and D and E connected at power on commutation.

Referring to fig. 1, when the refrigerant flow path switched by the flow path switching device 2 enters the outdoor side, it first passes through the defroster throttle device 17 and the gas side valve 13 connected in parallel to the defroster throttle device 17.

The refrigerant throttled by the defrosting throttle device 17 is selectively introduced into the outdoor heat exchanger 11-1 or 11-2, i.e., is alternately introduced into the outdoor heat exchangers 11-1 and 11-2, by the state of the defrosting switching device 15/16 corresponding to the outdoor heat exchanger 11-1/11-2.

Referring to fig. 1, second liquid pipe throttles 18-1 and 18-2 are provided on a pipe between a liquid pipe side of an outdoor heat exchanger 11-1/11-2 and a gas-liquid separator 14 in addition to first liquid pipe throttles 10-1 and 10-2 provided on a multi-split air conditioner.

Part of the refrigerant discharged from the compressor 1 can be throttled to a suitable pressure by the defrosting throttle device 17 and enter the outdoor heat exchanger 11-1 through the defrosting switching device 15 to be heat-exchanged and defrosted.

Part of the refrigerant discharged from the compressor 1 can be throttled to an appropriate pressure by the defrosting throttle device 17 and enter the outdoor heat exchanger 11-2 through the defrosting switching device 16 to be subjected to heat exchange defrosting.

The control means is for controlling the flow path switching means 2, the defrosting throttle means 17, the gas side valve 13, the defrosting switching means 15 and 16, the first liquid pipe throttle means 10-1 and 10-2, and the second liquid pipe throttle means 18-1 and 18-2 in the outdoor unit module to make the outdoor heat exchangers 11-1 and 11-2 perform defrosting rotation, that is, when the outdoor heat exchanger 11-1 performs defrosting. The outdoor heat exchanger 11-2 serves as an evaporator, and the outdoor heat exchanger 11-1 serves as an evaporator when the outdoor heat exchanger 11-2 is defrosted.

[ operation mode of air conditioner ]

Referring to fig. 1, the air conditioner has a normal heating operation mode, a normal cooling operation mode, a reverse defrosting operation mode, and a shift defrosting operation mode.

Heating mode of operation in general

The heating operation mode is not different from the common heating operation mode of the air conditioner.

In some embodiments, when the air conditioner is in the normal heating operation mode, referring to fig. 1, the defrost throttle 17 and the air side valve 13 in the outdoor unit module are both closed, the

defrost switch

15 and 16 are both powered on, the first pipe throttles 10-1 and 10-2 are both open, the outdoor fans 12-1 and 12-2 are both open, and the second pipe throttles 18-1 and 18-2 are both closed.

Wherein the

defrost switch

15 and 16 are powered up with D and E in communication and C and S in communication.

In some embodiments, the flow switching device 2 is electrically switched to connect D and E and C and S, the compressor 1 compresses the low-temperature and low-pressure refrigerant into a high-temperature and high-pressure state, and the refrigerant discharged from the compressor 1 passes through the gas side stop valve 3 and the first extension pipe 4 and enters the indoor heat exchangers 5-1 and 5-2 through D and E.

After heat exchange in the indoor heat exchangers 5-1 and 5-2, the refrigerant is condensed and released to form liquid refrigerant, and then the refrigerant passes through the indoor machine side throttling devices 7-1 and 7-2, the second extension pipe 8 and the liquid side stop valve 9 and enters the first liquid pipe throttling devices 10-1 and 10-2 to be throttled to a low-temperature low-pressure gas-liquid state.

Then the refrigerant enters the outdoor heat exchangers 11-1 and 11-2 to be evaporated and absorbed and becomes gaseous, and the refrigerant coming out of the outdoor heat exchangers 11-1 and 11-2 enters the gas-liquid separator 14 through C and S of the

defrosting switching devices

15 and 16, and finally is sucked into the compressor 1 to be compressed, thereby completing the heating cycle.

The outdoor fans 12-1 and 12-2 are always on throughout the normal heating operation mode.

Normal cooling mode of operation

The normal cooling operation mode is the same as the normal cooling operation mode of the air conditioner.

In some embodiments, when the air conditioner is in the normal cooling operation mode, referring to fig. 1, the defrost throttle 17 and the air side valve 13 in the outdoor unit module are both opened, the

defrost switch

15 and 16 are both de-energized, the first liquid pipe throttles 10-1 and 10-2 are both opened, the outdoor fans 12-1 and 12-2 are both opened, and the second liquid pipe throttles 18-1 and 18-2 are both closed.

Wherein D and C are communicated and E and S are communicated when the

defrosting switching devices

15 and 16 are powered off.

The four-way valve is powered off, the default conditions are that D and C are communicated and E and S are communicated, the compressor 1 compresses the low-temperature and low-pressure refrigerant into a high-temperature and high-pressure state, the refrigerant passes through the air-side valve 13 (as the defrosting throttle device 17 and the air-side valve 13 are connected in parallel, the refrigerant can completely flow through the air-side valve 13 as long as the air-side valve 13 is opened, and the refrigerant can completely flow through D and C of the

defrosting switching devices

15 and 16 and enters the outdoor heat exchangers 11-1 and 11-2 regardless of whether the defrosting throttle device 17 is opened or not.

The refrigerant is condensed and released heat after heat exchange of the outdoor heat exchangers 11-1 and 11-2 to become liquid refrigerant, then the refrigerant passes through the first liquid pipe throttling devices 10-1 and 10-2, the liquid side stop valve 9 and the second extension pipe 8, enters the indoor heat exchangers 5-1 and 5-2 to be evaporated and absorbed, and is changed into gas state, the refrigerant coming out of the indoor heat exchangers 5-1 and 5-2 passes through the first extension pipe 4, the gas side stop valve 3 and E and S of the flow path switching device 2 to enter the gas-liquid separator 14, and finally is sucked into the compressor 1 to be compressed, and the refrigeration cycle is completed.

The outdoor fans 12-1 and 12-2 are always on throughout the normal cooling operation mode.

Reverse defrost mode of operation

When the control device of the air conditioner detects and judges that the outdoor heat exchanger 11-1 and/or 11-2 needs defrosting, the compressor 1 firstly reduces the frequency or directly stops, and the indoor fans 6-1 and 6-2 and the outdoor fans 12-1 and 12-2 stop running.

Then, the flow path switching device 2 is turned off, the compressor 1 is started, the outdoor heat exchangers 11-1 and 11-2 are operated as condensers, and defrosting is started, that is, heating of all indoor units is stopped and defrosting of all the outdoor heat exchangers 11-1 and 11-2 is performed.

After defrosting is completed, the compressor 1 is stopped; then, the flow path switching device 2 is electrically reversed, the compressor 1 is restarted, the outdoor fans 12-1 and 12-2 are restarted, the indoor fans 6-1 and 6-2 are operated according to the cold air preventing program, and the air conditioner is restarted to the normal heating operation mode.

The reverse defrosting operation mode has the advantages of clean defrosting, but also has a plurality of defects (1) that the heating operation is stopped during defrosting, the indoor temperature is obviously reduced, and the use comfort of users is influenced; (2) during defrosting, the flow direction of the refrigerant needs to be changed, and particularly during heating operation after defrosting, because a large amount of refrigerant is stored in the gas-liquid separator 14 during defrosting, the high-low pressure difference is slowly established after defrosting, the heating capacity is low, and the heating cycle capacity is seriously influenced.

Alternate defrost mode of operation

The alternate defrosting operation mode is operated under the conditions that the outdoor heat exchanger needs to be defrosted and the indoor unit still needs to have certain heating capacity, so that the air conditioner can keep heating continuously while the outdoor heat exchanger to be defrosted (namely, the defrosting heat exchanger) is defrosted, the fluctuation of indoor temperature is reduced, and the heating comfort of a user is enhanced.

And in the defrosting process, the defrosting pressure of the defrosting heat exchanger is controlled, the latent heat of the refrigerant is utilized for defrosting, compared with hot gas bypass defrosting, sensible heat defrosting is utilized, the defrosting efficiency is high, the defrosting time is short, the heat acquired by the indoor unit is large, and the user comfort level is high.

In the air conditioner with a single outdoor unit module, when a plurality of outdoor heat exchangers in the single outdoor unit module are defrosted, a plurality of outdoor heat exchangers to be defrosted execute a rotation defrosting operation mode.

In an air conditioner having a plurality of outdoor unit modules, a plurality of outdoor heat exchangers perform sequential rotation defrosting (i.e., only one outdoor heat exchanger performs defrosting at a time), a defrosting process is performed according to defrosting conditions, and defrosting is started, for example, in a preset order, and a control device performs control of the defrosting heat exchanger (i.e., the outdoor heat exchanger that is performing defrosting) and the remaining outdoor heat exchangers in the defrosting process.

In the air conditioner with a plurality of outdoor unit modules, when a plurality of outdoor heat exchangers in the outdoor unit modules are combined and rotated for defrosting (namely, one outdoor heat exchanger in each outdoor unit module is selected to form a plurality of outdoor heat exchange combinations for defrosting at the same time, but two outdoor heat exchangers belonging to the same outdoor unit module are not defrosted at the same time), a defrosting process is started according to defrosting conditions, defrosting is started according to a preset combination sequence for example, and in the defrosting process, a control device executes control over the defrosting heat exchanger and the rest of the outdoor heat exchangers.

The defrosting condition can be judged according to the existing judgment basis, for example, the running time of the compressor and the temperature difference between the ambient temperature and the outdoor unit coil temperature are taken as the criterion.

In the above-described various defrosting processes, if there is a defrosting heat exchanger in the outdoor unit module, the control of the devices related to the defrosting heat exchanger in the outdoor unit module where the defrosting heat exchanger is located is the same, and the remaining devices in the outdoor unit module are maintained in the same state as in the normal heating operation mode. In some embodiments, referring to fig. 1, only the alternate defrosting of the outdoor heat exchangers 11-1 and 11-2 in a single outdoor unit module will be described.

S1: the process begins.

S2: the air conditioner performs a general heating operation mode.

S3: and judging whether the outdoor heat exchangers 11-1 and 11-2 meet defrosting conditions, if so, entering S4, and if not, continuing to execute a normal heating operation mode of S2.

S4: and sequentially executing a rotation defrosting operation mode aiming at the plurality of defrosting heat exchangers.

The outdoor heat exchangers 11-1 and 11-2 may be alternately defrosted according to the amount of frosting of the outdoor heat exchangers 11-1 and 11-2 to be defrosted (i.e., defrosting heat exchangers).

The outdoor heat exchangers 11-1 and 11-2 can be sequentially defrosted according to the sequence of the frost formation amount from large to small.

The determination of the frosting amount may be performed by detecting an index indicative of the frosting amount by a detecting means (not shown), such as at least one of the heating capacity of the outdoor heat exchangers 11-1 and 11-2, the evaporation temperature of the refrigerant, the indoor unit blow-out temperature, the liquid pipe temperature of the outdoor heat exchanger, and the like, and predicting the frosting amount of the outdoor heat exchangers 11-2 and 11-2 according to the change of the detection value.

For example, the frost formation amount is determined by the liquid pipe temperature of the outdoor heat exchanger, and the frost formation amount increases as the liquid pipe temperature of the outdoor heat exchanger decreases.

Assuming that the frosting amount of the outdoor heat exchanger 11-1 is greater than that of the outdoor heat exchanger 11-2, the outdoor heat exchanger 11-1 should be defrosted first to avoid that the normal operation of the outdoor heat exchanger 11-1 is affected by excessive frosting. The outdoor heat exchanger 11-2 is in a normal heating operation mode at this time.

That is, the outdoor heat exchanger 11-1 is performed as a defrosting heat exchanger, and the outdoor heat exchanger 11-2 is performed as an evaporator.

After the defrosting of the outdoor heat exchanger 11-1 is completed and the normal heating operation mode is entered, the outdoor heat exchanger 11-2 is defrosted.

That is, the switching of the outdoor heat exchanger 11-2 is performed as a defrosting heat exchanger, and the outdoor heat exchanger 11-1 is performed as an evaporator.

The process of defrosting the defrosting heat exchanger is described as follows.

S41: the flow path switching device 2 is controlled to be powered on, the defrosting throttle device 17, the gas side valve 13, the defrosting switching device 15 and the defrosting switching device 16 are controlled to make part of the refrigerant discharged from the compressor 1 enter the defrosting heat exchanger through the defrosting throttle device 17 and the defrosting switching device 15/16, the first liquid pipe throttle device communicated with the defrosting heat exchanger is cut off, the second liquid pipe throttle device communicated with the defrosting heat exchanger is controlled to be opened, and the rest outdoor heat exchanger is operated as an evaporator.

The outdoor heat exchanger 11-1 in the outdoor unit module is used as a defrosting heat exchanger to perform a defrosting process, and the outdoor heat exchanger 11-2 is used as an evaporator to perform a normal heating operation process.

The flow path switching device 2 is kept powered on, the defrosting throttle device 17 is controlled to be opened and the air side valve 13 is closed, the defrosting switching device 15 is powered off, the defrosting switching device 16 is powered on, the outdoor fan 12-1 is closed, the first liquid pipe throttle device 10-1 is closed, the second liquid pipe throttle device 18-1 is opened, and the rest of the devices are kept in the same state as in the normal heating operation mode.

Referring to fig. 1 again, the dotted arrows indicate the refrigerant flow direction during the defrosting process of the outdoor heat exchanger 11-1.

When entering the alternate defrosting operation mode, the compressor 1 compresses a low-temperature and low-pressure refrigerant into a high-temperature and high-pressure state, and discharges the high-temperature and high-pressure refrigerant.

A part of high-temperature and high-pressure refrigerant enters the indoor heat exchangers 5-1 and 5-2 through the flow path switching device 2D and E, the gas side stop valve 3 and the first extension pipe 4, is condensed and releases heat after heat exchange inside the indoor heat exchangers 5-1 and 5-2 to form liquid refrigerant, and then enters the first liquid pipe throttling device 10-2 to be throttled to a low-temperature low-pressure gas-liquid state through the indoor machine side throttling devices 7-1 and 7-2, the second extension pipe 8 and the liquid side stop valve 9.

Then the refrigerant enters the outdoor heat exchanger 11-2 to be evaporated and absorbed and turns into a gas state, and the refrigerant coming out of the outdoor heat exchanger 11-2 enters the gas-liquid separator 14 through C and S of the defrosting switching device 16 and is finally sucked into the compressor 1 to be compressed.

And the other part of the high-temperature and high-pressure refrigerant is throttled to a proper pressure by the defrosting throttling device 17 and then enters the defrosting switching device 15D and C to enter the outdoor heat exchanger 11-1 for heat exchange and defrosting.

The refrigerant after heat exchange in the outdoor heat exchanger 11-1 is throttled by the second pipe throttling device 18-1, enters the gas-liquid separator 14, and is finally sucked into the compressor 1 to be compressed.

In the application, the opening degree of the second liquid pipe throttling device 18-1 is controlled and adjusted according to the exhaust superheat degree of the compressor 1 and a target exhaust superheat degree range, so that the exhaust superheat degree of the compressor 1 tends to be maintained within the target exhaust superheat degree range, wherein the exhaust superheat degree indirectly controls the outlet temperature of the heat exchanger (detected by a temperature sensor 105 a); according to the defrosting pressure and the target defrosting pressure range, the opening degree of the defrosting throttle device 17 is controlled and adjusted, so that the defrosting pressure of the compressor 1 tends to be maintained in the target defrosting pressure range, the outlet temperature and the defrosting pressure of the heat exchanger are ensured, the defrosting time is shortened, the defrosting speed and efficiency are improved, the capacity of an indoor unit can be maximized when the air conditioner continuously heats and defrosts, and the indoor thermal comfort of a user is improved.

In defrosting the outdoor heat exchanger 11-1, how to control the opening degree of the second liquid pipe throttling device 18-1 and the opening degree of the defrosting throttling device 17 is described in detail with reference to fig. 2.

Before entering the defrosting process, it is necessary to set the initial opening degrees of the second liquid pipe throttle 18-1 and the defrosting throttle 17 at the time of defrosting.

For example, if the pre-defrost throttle 17 is off, it is necessary to set the initial opening degree (for example, fully open) of the pre-defrost throttle 17, and if the pre-defrost throttle 17 is on, the initial opening degree may be set to the opening degree before defrost, fully open, or the like.

S1': a target discharge superheat range of the compressor 1 and a target defrost pressure range are set.

In the present application, there is a range of target exhaust superheat Tdsho, for example, 10 ℃. ltoreq. Tdsho. ltoreq.40 ℃.

A target exhaust superheat range (Tdsho-lambda, Tdsho + lambda) is set, for example, 2 DEG & lt lambda & lt 5 ℃, in accordance with the target exhaust superheat Tdsho.

In the present application, the target defrosting pressure Pfo is a function Pfo = f (Ta) of the ambient temperature Ta, and the function Pfo = f (Ta) may be a preset function determined when the air conditioner is commissioned.

When the ambient temperature sensor detects the ambient temperature Ta, the target defrosting pressure Pfo can be obtained from the function f (Ta).

A target defrosting pressure range (Pfo-delta, Pfo + delta) is set based on the target defrosting pressure Pfo, for example, 0MPa < delta < 0.5 MPa.

S2': the discharge superheat Tdsh of the compressor 1 is calculated.

The discharge superheat Tdsh of the compressor 1 is calculated from the discharge pressure Pd (detected by the pressure sensor 101) and the discharge temperature Td.

The exhaust superheat Tdsh is equal to the difference between the exhaust temperature Td and a saturation temperature Tec corresponding to the exhaust pressure Pd, which saturation temperature Tec is found from the exhaust pressure query.

S3': comparing whether the exhaust superheat degree Tdsh is within a target exhaust superheat degree range;

s31': if the exhaust superheat degree Tdsh is within the target exhaust superheat degree range, keeping the opening degree of the second liquid pipe throttling device 18-1, and executing to S4'; if not, the opening degree of the second pipe orifice 18-1 is adjusted, and the process proceeds to S4'.

The procedure for specifically adjusting the opening degree of the second pipe orifice 18-1 is described below.

S32': if the exhaust superheat Tdsh is larger than the upper limit value of the target exhaust superheat range, the opening degree of the second pipe throttle device 18-1 is increased by one adjustment step number, and execution is performed to S4'.

That is, the next opening degree EV18-1(n +1) = EV18-1(n) + Δ EV18-1 of the second liquid pipe orifice 18-1, where Δ EV18-1 is the number of adjustment steps, where the number of adjustment steps may be selected to be 0.1% -10% pls (i.e., the number of steps) of the total opening degree.

S33': if the exhaust superheat Tdsh is less than the lower limit value of the target exhaust superheat range, the opening degree of the second pipe throttle 18-1 is decreased by one adjustment step number, and execution is carried out to S4'.

That is, the next opening degree EV18-1(n +1) = EV18-1(n) - Δ EV18-1 of the second liquid pipe orifice 18-1, where Δ EV18-1 is the number of adjustment steps, where the number of adjustment steps may be selected to be 0.1% -10% pls (i.e., the number of steps) of the total opening degree.

S4': whether the defrosting pressure Pf is within the target defrosting pressure range is compared, if so, the opening degree of the defrosting throttle device 17 is maintained and execution is performed to S42, and if not, the opening degree of the defrosting throttle device 17 is adjusted and execution is performed to S42.

The defrosting pressure Pf of the outdoor heat exchanger 11-1 is detected by the pressure sensor 103a in fig. 1.

The process of specifically adjusting the opening degree of the defroster throttle valve 17 is described as follows.

S41': if the defrosting pressure Pf is within the target defrosting pressure range, the opening degree of the defrosting throttle device 17 is maintained, and execution proceeds to S42.

S42': if the defrosting pressure Pf is greater than the upper limit value of the target defrosting pressure range, the opening degree of the defrosting throttle device 17 is decreased by one adjustment step number, and execution goes to S42.

That is, the next opening EV17(n +1) = EV17(n) - Δ EV17 of the defroster 17, where Δ EV17 is the number of adjustment steps, where the number of adjustment steps can be selected to be 0.1% -10% pls (i.e., the number of steps) of the total opening.

S43': if the defrosting pressure Pf is less than the lower limit value of the target defrosting pressure range, the opening degree of the defrosting throttle device 17 is increased by one adjustment step number, and execution goes to S42.

That is, the next opening EV17(n +1) = EV17(n) + Δ EV17 of the defroster 17, where Δ EV17 is the number of adjustment steps, which may be selected to be 0.1% to 10% pls (i.e., the number of steps) of the total opening.

S42: and judging whether the defrosting is finished or not, if so, exiting the defrosting process, otherwise, returning to S2', and readjusting the opening degrees of the second liquid pipe throttling device 18-1 and the defrosting throttling device 17.

As the defrosting end condition, it may be determined whether the defrosting time period T1 reaches a first preset time T1, or whether the outlet temperature Te1 of the outdoor heat exchanger 11-1 is greater than or equal to a first preset temperature Tef (e.g., 2 ℃ < Tef < 20 ℃) and is maintained for a certain time period T; and if one of the two conditions is met, indicating that the defrosting is finished, otherwise, continuing to judge.

Of course, the defrosting end condition is not limited to this, and for example, it may be determined by using whether or not the air pipe temperature Tg of the outdoor heat exchanger 11-1 is equal to or higher than the set temperature Tn and whether or not the suction pressure Ps of the compressor 1 is equal to or higher than the set pressure Po; alternatively, the number of times of adjustment of the opening degrees of the second liquid pipe throttling means 18-1 and the defrosting throttling means 17, and the like may be used.

Although S3 'is performed before S4' as described above, the order of S3 'and S4' is not limited, i.e., S4 'may also be performed before S3'.

After the defrosting of the outdoor heat exchanger 11-1 is finished, the defrosting process is exited, and then the normal heating operation process is entered.

The outdoor heat exchanger 11-1 exits the defrosting process and enters a normal heating operation process, which specifically comprises the following steps:

(1) controlling the defrosting throttle device 17 to be closed;

(2) controlling to open the gas side valve 13;

(3) controlling the defrosting switching device 15 to be electrified to enable the gas side of the defrosting heat exchanger 11-1 to be communicated with the gas-liquid separator 14;

(4) turning on the outdoor fan 12-1;

(5) opening the first pipe restriction 10-1;

(6) the second fluid line restriction 18-1 is closed.

In the defrosting process, the indoor side throttling devices 7-1 and 7-2 maintain control before defrosting, the second liquid pipe throttling device 10-2 maintains normal heating control, namely, the outlet superheat degree Ts2 of the outdoor heat exchanger 11-2 is controlled, namely, the temperature sensor 104b detects the outlet temperature T, the pressure sensor 103b detects the outlet pressure P, the outlet superheat degree Ts2 of the outdoor heat exchanger 11-2 is the difference between the outlet temperature T and the saturation temperature corresponding to the outlet pressure P, and the outlet superheat degree Ts2 is controlled within 0-2 ℃.

Similarly, when the outdoor heat exchanger 11-1 is out of defrost and the outdoor heat exchanger 11-2 is in defrost, the second liquid pipe throttling device 10-2 is also used for controlling the outlet superheat degree of the outdoor heat exchanger 11-1 within 0-2 ℃.

Thereafter, the outdoor heat exchanger 11-2 serves as a defrosting heat exchanger to enter a defrosting process, and the outdoor heat exchanger 11-1 serves as an evaporator to maintain a general heating operation process.

The flow path switching device 2 is kept powered on, the defrosting throttle device 17 is kept open and the gas side valve 13 is closed, the power-off defrosting switching device 16 is controlled to be turned off, the second liquid pipe throttle device 18-2 is opened, the outdoor fan 12-2 and the first liquid pipe throttle device 10-2 are closed, and the rest of the devices are kept in the same state as in the normal heating operation mode.

The defrosting process of the outdoor heat exchanger 11-2 is referred to as the defrosting process of the outdoor heat exchanger 11-1.

When the outdoor heat exchanger 11-2 is defrosted, the outdoor heat exchanger 11-1 performs a general heating operation process.

In the air conditioner with the single outdoor unit module, after the outdoor heat exchangers 11-1 and 11-2 are alternately defrosted for multiple times, a reverse defrosting operation mode is performed to completely defrost the outdoor heat exchangers 11-1 and 11-2. Of course, the reverse defrost mode of operation may be selected under other conditions.

[ three-pipe heating recovery function ]

The air conditioner of the present application may also be compatible with a three-pipe heat recovery function, see fig. 3, which shows a system structure diagram of the air conditioner with both two-pipe and three-pipe.

Referring to fig. 1 and 3, the air conditioner further includes a plurality of first switching valves a connected in parallel and a plurality of second switching valves b connected in parallel, the first switching valves a, the second switching valves b and one indoor heat exchanger corresponding to each other.

The first switching valve a is used to branch at least part of the refrigerant from the compressor 1 switched by the flow switching device 2 and flows into the indoor heat exchanger correspondingly.

One end of the second switching valve b is connected to a position where the first switching valve a is connected to the gas side of the indoor heat exchanger, and the other end is connected to the gas-liquid separator 14, and specifically, the other end communicates with the gas-liquid separator 14 through an extension pipe 20 and a gas-side shutoff valve 19.

Referring to fig. 3, the air conditioner has a main cooling operation mode, a main heating operation mode, and a heating defrost mode in the main heating operation mode, in addition to the above-described operation modes.

The main cooling operation mode, that is, the indoor unit is in both cooling and heating states, and the cooling load is greater than the heating load, and the outdoor heat exchanger serves as a condenser.

In the main cooling operation mode, it is assumed that the indoor heat exchanger 5-1 is used as an evaporator (i.e., the indoor heat exchanger 5-1 cools down) and the indoor heat exchanger 5-2 is used as a condenser (i.e., the indoor heat exchanger 5-2 heats up).

Referring to fig. 3, the flow path switching device 2 in the outdoor unit module is powered on, the defrost throttle device 17 and the air side valve 13 are both opened, the

defrost switching devices

15 and 16 are both powered off, the first pipe throttle devices 10-1 and 10-2 are both opened, the outdoor fans 12-1 and 12-2 are both opened, the second pipe throttle devices 18-1 and 18-2 are both closed, the first switching valve a (i.e., the first switching valve 21 a) connected to the indoor heat exchanger 5-1 is controlled to be closed and the second switching valve b (i.e., the second switching valve 21 b) is controlled to be opened, the first switching valve a (i.e., the first switching valve 22 a) connected to the indoor heat exchanger 5-2 is controlled to be opened and the second switching valve b (i.e., the second switching valve 22 b) is controlled to be closed.

Wherein D and C are communicated and E and S are communicated when the

defrost switching devices

15 and 16 are de-energized.

The flow path switching device 2 is electrified and reversed, D is communicated with E, C is communicated with S, and the compressor 1 compresses a low-temperature and low-pressure refrigerant into a high-temperature and high-pressure state and is divided into two parts.

A portion enters the outdoor heat exchangers 11-1 and 11-2 through the air side valve 13 to D and C of the

defrost switching devices

15 and 16. After heat exchange in the outdoor heat exchangers 11-1 and 11-2, the refrigerant is condensed to release heat and becomes liquid refrigerant, and then the refrigerant passes through the first pipe throttling devices 10-1 and 10-2, the liquid side stop valve 9 and the second extension pipe 8 and reaches the side of the indoor heat exchanger 5-1.

The other part of the refrigerant passes through the flow path switching device 2D and E, and part of the refrigerant discharged by the compressor 1 enters the indoor heat exchanger 5-2 through the gas side stop valve 3, the first extension pipe 4 and the first switching valve 22a to be subjected to internal heat exchange, condensed and released heat to form liquid refrigerant, and then the refrigerant passes through the indoor machine side throttling device 7-2, joins with the refrigerant from the outdoor side, enters the indoor machine side throttling device 7-1 to be throttled and depressurized to a gas-liquid state.

Then, the refrigerant enters the indoor heat exchanger 5-1 to be evaporated and absorbed heat, turns into a gaseous state, enters the gas-liquid separator 14 through the second switching valve 21b, the extension pipe 20, and the gas-side shutoff valve 19, and is finally sucked into the compressor 1 to be compressed, thereby completing the main refrigeration cycle.

The main heating mode, i.e., the indoor unit has two states of cooling and heating, and the heating load is greater than the cooling load, when the outdoor heat exchanger is used as an evaporator.

In the main heating mode, it is assumed that the indoor heat exchanger 5-1 serves as a condenser (i.e., the indoor heat exchanger 5-1 heats) and the indoor heat exchanger 5-2 serves as an evaporator (i.e., the indoor heat exchanger 5-2 cools).

Referring to fig. 3, the flow path switching device 2 in the outdoor unit module is powered on, the defrost throttle device 17 and the air side valve 13 are all closed, the

defrost switching devices

15 and 16 are all powered on, the first pipe throttles 10-1 and 10-2 are all open, the outdoor fans 12-1 and 12-2 are all open, the second pipe throttles 18-1 and 18-2 are all closed, the first switching valve 21a is controlled to be open and the second switching valve 21b is controlled to be closed, the first switching valve 22a is controlled to be closed and the second switching valve 22b is controlled to be open.

Wherein D and E are in communication and C and S are in communication when the

defrost switch

15 and 16 are powered up.

The flow path switching device 2 is electrified and reversed, D is communicated with E, C is communicated with S, the compressor 1 compresses a low-temperature and low-pressure refrigerant into a high-temperature and high-pressure state, the refrigerant enters the indoor heat exchanger 5-1 through the gas side stop valve 3, the first extension pipe 4 and the first switching valve 21a to be subjected to internal heat exchange, then is condensed and releases heat to form a liquid refrigerant, and then the refrigerant flows out through the indoor machine side throttling device 7-1 and is divided into two parts.

And a part of the refrigerant enters the first liquid pipe throttling devices 10-1 and 10-2 through the second extension pipe 8 and the liquid side stop valve 9 to be throttled to a low-temperature low-pressure gas-liquid two state, then enters the outdoor heat exchangers 11-1 and 11-2 to be evaporated and absorbed, and is changed into a gas state, and the refrigerant coming out of the outdoor heat exchangers 11-1 and 11-2 flows out through C and S of the

defrosting switching devices

15 and 16.

The other part is throttled and depressurized by the indoor-side throttling device 7-2, enters the indoor heat exchanger 5-2, is evaporated and absorbs heat, is changed into a gas state, passes through the second switching valve 22b, the extension pipe 20 and the gas-side stop valve 19, is merged with the refrigerant flowing out of the

defrosting switching devices

15 and 16 and passing through the C and S, enters the gas-liquid separator 14, is finally sucked into the compressor 1 for compression, and completes the main heating cycle.

The heating and defrosting operation mode in the main heating operation mode is that the indoor unit is in two states of cooling and heating, the heating load is greater than the cooling load, and the outdoor heat exchangers 11 to 1/11-2 perform sequential alternate defrosting.

In the heating and defrosting operation mode in the main heating operation mode, the process in which the outdoor heat exchanger performs the alternate defrosting is maintained in the same state as the two-pipe air conditioner in the alternate defrosting as described above, except for the control of the plurality of first switching valves a, the plurality of second switching valves b, and the indoor-side throttling devices 7-1 and 7-2.

In the heating defrost operation mode in the main heating mode, it is assumed that the indoor heat exchanger 5-1 is used as a condenser (i.e., the indoor heat exchanger 5-1 heats) and the indoor heat exchanger 5-2 is used as an evaporator (i.e., the indoor heat exchanger 5-2 cools), and the outdoor heat exchanger 11-1 is a defrost heat exchanger.

Referring to fig. 3, the flow path switching device 2 in the outdoor unit module is powered on, the defrost throttling device 17 is opened, the gas side valve 13 is closed, the defrost switching device 15 is powered off and the defrost switching device 16 is powered on, the pipe throttling device 10-1 is closed and the pipe throttling device 10-2 is opened, the outdoor fan 12-1 is closed and the outdoor fan 12-2 is opened, the second pipe throttling device 18-1 is opened and the second pipe throttling device 18-2 is closed, the first switching valve 21a is controlled to be opened and the second switching valve 21b is controlled to be closed, the first switching valve 22a is controlled to be closed and the second switching valve 22b is controlled to be opened.

Wherein the defrost switch 15 is de-energized, wherein D and C are in communication and E and S are in communication. When the defrost switch 16 is powered up, D and E are in communication and C and S are in communication.

The flow path switching device 2 is powered on, D is communicated with E, C is communicated with S, and the compressor 1 compresses the low-temperature and low-pressure refrigerant into a high-temperature and high-pressure state and then divides the refrigerant into two paths.

One path is throttled to a proper pressure by the defrosting throttle device 17 and then enters the defrosting switching device 15D and C to enter the outdoor heat exchanger 11-1 for heat exchange and defrosting.

The refrigerant heat-exchanged from the outdoor heat exchanger 11-1 flows out through the second liquid-tube throttling device 18-1.

The other path enters the indoor heat exchanger 5-1 through the flow path switching devices 2D and E, the gas side stop valve 3, the first extension pipe 4 and the first switching valve 21a for heat exchange, is condensed and releases heat to form liquid refrigerant, and then the refrigerant flows out through the indoor machine side throttling device 7-1 and is divided into two parts.

One part of the refrigerant enters the liquid pipe throttling device 10-2 through the second extension pipe 8 and the liquid side stop valve 9 to be throttled to a low-temperature low-pressure gas-liquid two state, and then enters the outdoor heat exchanger 11-2 to be evaporated and absorbed to be changed into a gas state, and the refrigerant coming out of the outdoor heat exchanger 11-2 flows out with the C and the S passing through the defrosting switching device 16.

The other part of the refrigerant is throttled and decompressed by the indoor unit side throttling device 7-2, enters the indoor heat exchanger 5-2, is evaporated and absorbs heat, is changed into a gas state, passes through the second switching valve 22b, the extension pipe 20 and the gas side stop valve 19, is merged with the refrigerant flowing out through the defrosting switching device 16C and S and the refrigerant flowing out through the second liquid pipe throttling device 18-1, enters the gas-liquid separator 14, is finally sucked into the compressor 1 for compression, and completes the heating defrosting mode under the main heating cycle.

Referring to fig. 3, when the triple-pipe heating recovery function is involved, the control of each device in the outdoor unit module is the same as the control of each device in the outdoor unit module in the two-pipe air conditioner when the alternate defrosting is performed.

[ separation of wind field ]

Since the corresponding outdoor fan 12-2 of the outdoor heat exchanger 11-2 is kept in operation when the outdoor heat exchanger 11-1 is defrosted, in order to avoid the situation that the outdoor heat exchanger 11-1 cannot be defrosted effectively due to the wind field generated by the outdoor fan 12-2 blowing through the outdoor heat exchanger 11-1, a separating device 102 for separating the wind field is provided in the present application (see patent document No. 202010279447.2 entitled "outdoor unit of air conditioner").

In the present application, the outdoor fans 12-1 and 12-2 are independently controlled by the control device, respectively, and the outdoor heat exchanger 11-1 and the outdoor fan 12-1 form a first wind field, and the outdoor heat exchanger 11-2 and the outdoor fan 12-1 form a second wind field, and the partition device 102 serves to separate the first wind field and the second wind field.

That is, it does not blow wind to the outdoor heat exchanger 11-2 when the outdoor fan 12-1 is operated and the outdoor fan 12-2 is not operated, and it does not blow wind to the outdoor heat exchanger 11-1 when the outdoor fan 12-2 is operated and the outdoor fan 12-1 is not operated.

Thus, when the outdoor heat exchanger 11-1 performs defrosting, since the partition device 102 separates the first wind field and the second wind field, the first wind field is not affected even if the outdoor fan 12-2 is still operated.

Therefore, the situation that when the outdoor heat exchanger 11-1 is defrosted, the surface of the outdoor heat exchanger is blown by wind is effectively avoided, the situation that the outdoor temperature is low, the defrosting cannot be effectively carried out due to overlarge condensation load is further prevented, and uninterrupted heating of a full-temperature area can be realized.

In addition, when the outdoor fan 12-1 stops running (i.e. the outdoor heat exchanger 11-1 is defrosting), the rotating speed of the outdoor fan 12-2 can be properly increased, the heating effect is further enhanced, the indoor temperature fluctuation is reduced, and the heating capacity of the air conditioner and the heating comfort of users are greatly improved.

And when the outdoor heat exchanger 11-1 exits the defrosting process and enters the normal heating operation process, the outdoor fan 12-1 is turned on correspondingly and the outdoor fan 12-2 of the outdoor heat exchanger 11-2 is turned off.

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

1. An air conditioner, comprising:

at least one indoor unit;

at least one outdoor unit module, each outdoor unit module includes:

a compressor;

a defrost throttle for throttling a portion of refrigerant from the compressor;

an air side valve connected in parallel with the defrost throttling device;

a plurality of outdoor heat exchangers arranged in parallel;

2. The air conditioner according to claim 1,

in defrosting the defrosting heat exchanger, the control device is configured to:

3. The air conditioner according to claim 2,

controlling and opening the second liquid pipe throttling device, and controlling and adjusting the opening degree of the second liquid pipe throttling device according to the exhaust superheat degree and the target superheat degree range of the compressor, specifically:

setting a target exhaust superheat range of the compressor;

calculating the discharge superheat degree of the compressor;

comparing whether the exhaust superheat degree is within the target exhaust superheat degree range, if so, keeping the current opening degree of the second liquid pipe throttling device, and if not, adjusting the opening degree of the second liquid pipe throttling device;

controlling to open the defrosting throttle device, and controlling the opening of the defrosting throttle device according to the defrosting pressure and the target defrosting pressure range, specifically:

setting a target defrosting pressure range;

calculating the defrosting pressure of the heat exchanger to be defrosted;

4. The air conditioner according to claim 3,

adjusting the opening degree of the second liquid pipe throttling device, specifically:

when the exhaust superheat degree is smaller than the lower limit value of the target exhaust superheat degree range, reducing the opening degree of the second liquid pipe throttling device;

adjusting the opening degree of the defrosting throttle device, specifically:

5. The air conditioner according to any one of claims 1 to 4, wherein the control device is configured to:

6. The air conditioner according to claim 5, wherein the control device is configured to:

controlling to close the defrosting throttling device;

controlling to open the air side valve;

7. The air conditioner according to any one of claims 1 to 4,

the target defrost pressure range is related to an ambient temperature.

8. The air conditioner according to claim 1, further comprising:

9. The air conditioner of any one of claims 1 to 4 and 8, wherein the outdoor unit module further comprises:

a separation device for separating adjacent wind farms;

10. The air conditioner according to claim 9,

when the outdoor heat exchangers in each outdoor unit module are defrosting, the rotating speed of outdoor fans corresponding to the other outdoor heat exchangers which are not defrosting in the outdoor unit module is increased.