阅读说明：本技术 一种空调器 (Air conditioner ) 是由 张恒 夏兴祥 孟建军 唐亚洲 高永坤 于 2020-11-30 设计创作，主要内容包括：本发明公开了空调器,包括：室内机和室外机,室外机包括：压缩机；流路节流装置；第一控制阀,其与流路节流装置并联；并列设置的两个室外换热器；两个除霜切换装置,其各自对应一个室外换热器,用于切换室外换热器与流路节流装置或与气液分离器连通；两个液管节流装置；节流装置,其一端连接在一个液管节流装置连接对应室外换热器液侧的位置处,另一端连接另一个液管节流装置连接对应室外换热器的位置处；在室外机中的一个室外换热器需要除霜时,控制装置控制待除霜的室外换热器作为除霜换热器执行,另一个室外换热器作为蒸发器执行。本发明实现对除霜换热器进行轮换除霜,实现室内不间断制热,提升室内热舒适性。(The invention discloses an air conditioner, comprising: indoor set and off-premises station, the off-premises station includes: a compressor; a flow path throttling device; a first control valve connected in parallel with the flow path throttling device; two outdoor heat exchangers arranged in parallel; the two defrosting switching devices respectively correspond to one outdoor heat exchanger and are used for switching the outdoor heat exchanger to be communicated with the flow path throttling device or the gas-liquid separator; two liquid pipe throttling devices; one end of the throttling device is connected with the position where one liquid pipe throttling device is connected with the liquid side of the corresponding outdoor heat exchanger, and the other end of the throttling device is connected with the position where the other liquid pipe throttling device is connected with the corresponding outdoor heat exchanger; when one outdoor heat exchanger in the outdoor unit needs defrosting, the control device controls the outdoor heat exchanger to be defrosted to be executed as a defrosting heat exchanger, and the other outdoor heat exchanger to be executed as an evaporator. The invention realizes the alternate defrosting of the defrosting heat exchangers, realizes the indoor uninterrupted heating and improves the indoor thermal comfort.)

1. An air conditioner, comprising:

an indoor unit;

an outdoor unit, comprising:

a compressor;

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

flow path throttling means for throttling part of the refrigerant from the compressor switched by the flow path switching means;

a first control valve connected in parallel with the flow path throttling device;

two outdoor heat exchangers are arranged in parallel;

the defrosting switching devices are 2 and are respectively connected with one outdoor heat exchanger and used for switching the outdoor heat exchanger to be communicated with the flow path throttling device or the gas-liquid separator;

two liquid pipe throttling devices which are respectively connected with the indoor unit and each outdoor heat exchanger;

one end of the throttling device is connected with the position where one liquid pipe throttling device is connected with the liquid side of the corresponding outdoor heat exchanger, and the other end of the throttling device is connected with the position where the other liquid pipe throttling device is connected with the corresponding outdoor heat exchanger;

the control device controls the flow path switching device, the flow path throttling device, the first control valve, the defrosting switching device, the liquid pipe throttling device and the throttling device when one outdoor heat exchanger in the outdoor unit needs defrosting, so that the outdoor heat exchanger to be defrosted is used as a defrosting heat exchanger to be executed, and the rest outdoor heat exchanger is used as an evaporator to be executed;

when the defrosting heat exchanger defrosts, the control device controls the flow path switching device to be opened; controlling to open the flow path throttling device; controlling the defrosting switching device to communicate the refrigerant flowing out of the flow path throttling device with a main air pipe of the defrosting heat exchanger; controlling a liquid pipe throttling device communicated with the defrosting heat exchanger and a first control valve to be closed; controlling the throttling device to be opened.

2. The air conditioner according to claim 1,

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

controlling to open the throttling device, and controlling and adjusting the opening degree of the throttling device according to the outlet supercooling degree of the defrosting heat exchanger and the target outlet supercooling degree range;

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

3. The air conditioner according to claim 1,

controlling and opening the throttling device, and controlling and adjusting the opening degree of the throttling device according to the outlet supercooling degree of the defrosting heat exchanger and the target outlet supercooling degree range, wherein the method specifically comprises the following steps:

setting a target outlet supercooling degree range of the defrosting heat exchanger;

calculating the supercooling degree of the outlet of the defrosting heat exchanger;

comparing whether the outlet supercooling degree is within the target outlet supercooling degree range, if so, keeping the current opening degree of the throttling device, and if not, adjusting the opening degree of the throttling device;

controlling to open the flow path throttling device, and controlling the opening degree of the flow path throttling 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;

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

4. The air conditioner according to claim 3,

adjusting the opening degree of the throttling device, specifically:

when the outlet supercooling degree is larger than the upper limit value of the target outlet supercooling degree range, increasing the opening degree of the throttling device;

when the outlet supercooling degree is smaller than the lower limit value of the target outlet supercooling degree range, reducing the opening degree of the throttling device;

adjusting the opening degree of the flow path throttling device, specifically:

reducing the opening degree of the flow path throttling device when the defrosting pressure is larger than the upper limit value of the target defrosting pressure range;

and increasing the opening degree of the flow path throttling device when the defrosting pressure is smaller than the lower limit value of the target defrosting pressure range.

5. The air conditioner according to any one of claims 1 to 4, wherein 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, controlling the defrosting heat exchanger to exit the defrosting process and enter a normal heating operation process.

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

the defrosting heat exchanger exits the defrosting process and enters a normal heating operation process, and at least comprises the following steps:

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

and controlling to open a liquid pipe throttling device communicated with the defrosting heat exchanger.

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:

2 indoor heat exchangers are arranged in parallel;

2 parallel first switching valves, each of which is correspondingly connected with one indoor heat exchanger, and the first switching valves are used for branching at least part of refrigerant from the compressor switched by the flow path switching device and correspondingly flowing into the gas side of the corresponding indoor heat exchanger;

2 second switching valves which are connected in parallel and are respectively correspondingly connected with an indoor heat exchanger, wherein one end of each second switching valve is connected to the position where the first switching valve is connected with the air side of the indoor heat exchanger, and the other end of each second switching valve is connected with a gas-liquid separator;

the first switching valve and the second switching valve are respectively controlled by the control device.

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

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

a separation device for separating adjacent wind farms;

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

10. The air conditioner according to claim 9,

when one of the outdoor heat exchangers in the outdoor unit is defrosting, the controller controls the rotating speed corresponding to the other outdoor heat exchanger to be increased.

Technical Field

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

Background

The technology of air source heat pumps is becoming mature and is widely used in the domestic and commercial fields. The air source heat pump comprises indoor units and outdoor units, wherein each indoor unit is provided with a plurality of indoor heat exchangers and corresponding indoor fans, the indoor heat exchangers are arranged in parallel, each outdoor unit 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 connecting pipelines, and when at least two outdoor heat exchangers exist in one outdoor unit, 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 reversing is mainly realized by opening a four-way valve, an outdoor unit is switched into a condenser, the defrosting is realized 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, under the condition of not changing the flow direction of a system refrigerant, the exhaust gas of a compressor is led into one outdoor heat exchanger to be defrosted by using a bypass branch to defrost, and other outdoor heat exchangers still maintain heating operation, so that uninterrupted heating is realized,

The uninterrupted heating defrosting mode has the following defects: 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:

an air conditioner comprising:

an indoor unit;

an outdoor unit, comprising:

a compressor;

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

flow path throttling means for throttling part of the refrigerant from the compressor switched by the flow path switching means;

a first control valve connected in parallel with the flow path throttling device;

two outdoor heat exchangers are arranged in parallel;

the defrosting switching devices are 2 and are respectively connected with one outdoor heat exchanger and used for switching the outdoor heat exchanger to be communicated with the flow path throttling device or the gas-liquid separator;

two liquid pipe throttling devices which are respectively connected with the indoor unit and each outdoor heat exchanger;

one end of the throttling device is connected with the position where one liquid pipe throttling device is connected with the liquid side of the corresponding outdoor heat exchanger, and the other end of the throttling device is connected with the position where the other liquid pipe throttling device is connected with the corresponding outdoor heat exchanger;

the control device controls the flow path switching device, the flow path throttling device, the first control valve, the defrosting switching device, the liquid pipe throttling device and the throttling device when one outdoor heat exchanger in the outdoor unit needs defrosting, so that the outdoor heat exchanger to be defrosted is used as a defrosting heat exchanger to be executed, and the rest outdoor heat exchanger is used as an evaporator to be executed;

when the defrosting heat exchanger defrosts, the control device controls the flow path switching device to be opened; controlling to open the flow path throttling device; controlling the defrosting switching device to communicate the refrigerant flowing out of the flow path throttling device with a main air pipe of the defrosting heat exchanger; controlling a liquid pipe throttling device communicated with the defrosting heat exchanger and a first control valve to be closed; controlling the throttling device to be opened.

Thus, when the air conditioner performs alternate defrosting, the control flow path switching device is opened, the liquid pipe throttling device and the first control valve are controlled to be cut off, the flow path 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 gas pipe of the defrosting heat exchanger, the throttling device is controlled to be opened, the defrosting pressure of the defrosting heat exchanger can be controlled, defrosting is achieved by using latent heat of the refrigerant, the defrosting speed is high, the capacity of the indoor unit is maximized, uninterrupted heating of the air conditioner is achieved, the thermal comfort of a user is met, and the indoor temperature rising speed is high after defrosting.

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

controlling to open the throttling device, and controlling and adjusting the opening degree of the throttling device according to the outlet supercooling degree of the defrosting heat exchanger and the target outlet supercooling degree range;

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

In this application, control is opened throttling arrangement, according to defrosting heat exchanger's export supercooling degree and target export supercooling degree scope, control adjustment throttling arrangement's aperture specifically is:

setting a target outlet supercooling degree range of the defrosting heat exchanger;

calculating the supercooling degree of the outlet of the defrosting heat exchanger;

comparing whether the outlet supercooling degree is within the target outlet supercooling degree range, if so, keeping the current opening degree of the throttling device, and if not, adjusting the opening degree of the throttling device;

the throttling device and the flow path throttling device are the throttling device and the flow path throttling device in the outdoor unit module where the defrosting heat exchanger is located.

In this application, the opening of the flow path throttling device is controlled to be opened, and the opening of the flow path throttling device is controlled 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;

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

In this application, the opening degree of the throttling device is adjusted, specifically:

when the outlet supercooling degree is larger than the upper limit value of the target outlet supercooling degree range, reducing the opening degree of the throttling device;

and when the outlet supercooling degree is smaller than the lower limit value of the target outlet supercooling degree range, increasing the opening degree of the throttling device.

In this application, the opening degree of the flow path throttling device is adjusted, specifically:

increasing the opening degree of the flow path throttling device when the defrosting pressure is greater than the upper limit value of the target defrosting pressure range;

and when the defrosting pressure is smaller than the lower limit value of the target defrosting pressure range, reducing the opening degree of the flow path throttling 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 normal heating operation process, and at least comprises the following steps:

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

and controlling to open a liquid pipe 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:

2 indoor heat exchangers are arranged in parallel;

2 parallel first switching valves, each of which is correspondingly connected with one indoor heat exchanger, and the first switching valves are used for branching at least part of refrigerant from the compressor switched by the flow path switching device and correspondingly flowing into the gas side of the corresponding indoor heat exchanger;

2 second switching valves which are connected in parallel and are respectively correspondingly connected with an indoor heat exchanger, wherein one end of each second switching valve is connected to the position where the first switching valve is connected with the air side of the indoor heat exchanger, and the other end of each second switching valve is connected with a gas-liquid separator;

the first switching valve and the second switching valve are respectively controlled by the control device.

In this application, the outdoor unit further includes:

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

a separation device for separating adjacent wind farms;

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

In the application, when one of the outdoor heat exchangers in the outdoor unit is defrosting, the controller controls to increase the rotating speed corresponding to the other outdoor heat exchanger.

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 defrosting an outdoor heat exchanger in an embodiment of the air conditioner according to the present invention;

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 is the air conditioning outdoor unit described above.

The air conditioner designed by the application is a single-unit air conditioner.

The air conditioner includes an indoor unit and an outdoor unit.

The indoor unit may correspondingly include a plurality of indoor heat exchangers, for example, in some embodiments, the indoor unit includes 2 indoor heat exchangers, which are the indoor heat exchangers 11-1 and 11-2 and an indoor fan (not shown), and 2 indoor fans and a fan for blowing cold or hot air generated by the indoor heat exchangers 11-1 and 11-2 to the indoor space.

The air conditioner also comprises an outdoor unit.

The outdoor unit W1, for example, in some embodiments, is assumed to be W1, which includes a compressor, a flow path switching device, a flow path throttling device, a first control valve, two outdoor heat exchangers arranged in parallel, two defrosting switching devices corresponding to the two outdoor heat exchangers, two liquid pipe throttling devices, two outdoor fans, one throttling device, and a gas-liquid separator.

The outdoor unit W1 includes two outdoor heat exchangers in the outdoor unit W1.

The outdoor unit W1 outdoor unit W1 includes a compressor 1, a flow path switching device 3, a flow path throttling device 19, a first control valve 18, two outdoor heat exchangers 4-1 and 4-2 arranged in parallel, two defrosting switching devices 21 and 20 respectively corresponding to the outdoor heat exchangers 4-1 and 4-2, two liquid pipe throttling devices 6-1 and 6-2, two outdoor fans 5-1 and 5-2, a throttling device 28, and a gas-liquid separator 14.

The flow path switching device 3 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 3 is a four-way valve having four terminals C, D, S and E. The flow path switching device 3 may be a pilot type three-way valve or other low resistance three-way valve.

Referring to fig. 1, for a two-pipe single-unit air conditioner, when the flow switching device 3 is powered off, the default C and D are connected, and the default S and E are connected, so that the indoor heat exchangers 11-1 and 11-2 are used as evaporators, and the outdoor heat exchangers 4-1 and 4-2 are used as condensers, and the air conditioner performs cooling.

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 11-1 and 11-2 are used as condensers, the outdoor heat exchangers 4-1 and 4-2 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.

There is no difference in defrosting the outdoor heat exchanger 4-1 or 4-2 in the outdoor unit W1 or the outdoor heat exchanger 4-1 (or 4-2) in the outdoor unit W1, regardless of whether the two-pipe refrigerant system or the three-pipe heat recovery refrigerant system.

In the application, when the outdoor heat exchanger 4-1 and the outdoor heat exchanger 4-2 in the outdoor unit W1 perform defrosting, defrosting is performed alternately, that is, when the outdoor heat exchanger 4-1 performs defrosting, the outdoor heat exchanger 4-2 performs heating operation, and when the outdoor heat exchanger performs defrosting, the outdoor heat exchanger 4-1 performs heating operation, thereby realizing uninterrupted heating for defrosting.

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.

In the present application, the first control valve 18 is a solenoid valve or a large-diameter two-way valve (e.g., a reversible two-way valve with extremely small resistance) and does not have a throttling function. The first control valve 18 is connected in parallel with the flow path switching device 3, and when the outdoor heat exchanger is used as a condenser, the first control valve 18 can be opened to enable the refrigerant to flow through the first control valve 18, so that the pressure loss of the flow path is reduced, and the performance of the whole machine is improved.

In the present application, the flow path throttling device 19, the liquid pipe throttling device 6-1/6-2, and the throttling device 28 may be fixed-opening throttling elements such as electronic expansion valves, two-way thermostatic expansion valves, or capillary tubes.

The flow path throttling device 19 and the throttling device 28 can be used for adjusting the defrosting pressure when one outdoor heat exchanger is defrosted, and further preventing the defrosting pressure from being too high to cause heat waste.

In the outdoor unit W1, the defrosting switching device 21/20 is a four-way valve having four terminals C, D, S and E, and is connected to C and D and S and E by default when power is off, and is connected to C and S and D and E when power is on and reversed. The two defrost switching devices 21 and 20 may also be pilot type three-way valves or other low resistance three-way valves.

Referring to fig. 1, when the refrigerant discharged from the compressor 1 flows out through the check valve 2 and enters the outdoor side after being switched by the flow switching device 3, the refrigerant first passes through the flow throttling device 19 and/or the first control valve 18 connected in parallel to the flow throttling device 19.

The refrigerant throttled by the flow path throttling device 19 enters the outdoor heat exchanger 4-1 or 4-2 selectively by the state of the defrosting switching device 21/20 corresponding to the outdoor heat exchanger 4-1/4-2, that is, flows into the outdoor heat exchangers 4-1 and 4-2 alternately.

The part of the refrigerant discharged from the compressor 1 switched by the flow path switching device 3 can be throttled to an appropriate pressure by the flow path throttling device 19 and enter the outdoor heat exchanger 4-1 through the defrosting switching device 21 to be subjected to heat exchange defrosting.

The part of the refrigerant discharged from the compressor 1, which is switched by the flow path switching device 3, can be throttled to an appropriate pressure by the flow path throttling device 19 and then enter the outdoor heat exchanger 4-2 through the defrosting switching device 20 to be subjected to heat exchange defrosting.

The control device is used for controlling the flow path switching device 3, the flow path throttling device 19, the first control valve 18, the defrosting switching devices 21 and 20, the liquid pipe throttling devices 6-1 and 6-2 and the throttling device 28 in the outdoor unit W1 to defrost one outdoor heat exchanger in the outdoor unit.

[ 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 the normal heating operation of the outdoor unit W1, the control method and the refrigerant flow direction of the components are the same as those in the normal heating operation mode of the air conditioner.

Referring to fig. 1, in some embodiments, when the air conditioner is in the normal heating operation mode, the flow path throttling device 19 in the outdoor unit W1 may be at any opening degree (preferably, closed), the first control valve 18 may be closed or opened (preferably, opened), the defrost switch devices 21 and 20 are electrically conducted, the liquid pipe throttling devices 6-1 and 6-2 are opened, the outdoor fans 5-1 and 5-2 are opened, and the throttling device 28 may be at any opening degree (preferably, closed).

Wherein D and E and C and S in the defrost switching devices 21 and 20 are communicated.

In some embodiments, the flow switching device 3 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 check valve 2, the D and E of the flow switching device 3, and the first extension pipe 12 to enter the indoor heat exchangers 11-1 and 11-2.

The refrigerant is condensed and released heat after heat exchange in the indoor heat exchangers 11-1 and 11-2 to become liquid refrigerant, then the refrigerant passes through the indoor machine side throttling devices 10-1 and 10-2, the second extension piping 9 and the liquid side stop valve 8, enters the liquid pipe throttling devices 6-1 and 6-2 to be throttled to a low-temperature low-pressure gas-liquid two-state, and the two-phase refrigerant enters the outdoor heat exchangers 4-1 and 4-2 to be evaporated and absorbed heat and then becomes gaseous state.

The refrigerants coming out of the outdoor heat exchangers 4-1 and 4-2 pass through the defrosting switching devices 21 and 20, C and S enter the gas-liquid separator 14, and are finally sucked into the compressor 1 to be compressed, so that the heating cycle is completed.

The outdoor fans 5-1 and 5-2 are always turned 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.

Referring to fig. 1, in some embodiments, when the air conditioner is in the normal cooling operation mode, the flow path throttling device 19 in the outdoor unit W1 is at an arbitrary opening degree (preferably, opened), the first control valve 18 is opened, the defrosting switching devices 21 and 20 are both closed by power failure, the pipe throttling devices 6-1 and 6-2 are both opened, the outdoor fans 5-1 and 5-2 are both opened, and the throttling device 28 is at an arbitrary opening degree (preferably, closed).

Wherein D and C and E and S in the defrost switching devices 21 and 20 are communicated.

The flow path switching device 2 is powered off and closed, 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 check valve 2 and the first control valve 18 (because the flow path throttling device 19 is connected with the first control valve 18 in parallel, so as long as the first control valve 18 is opened, the refrigerant can completely flow through the first control valve 18 and then enter the D and C of the defrosting switching devices 21 and 20 and then enter the outdoor heat exchangers 4-1 and 4-2 no matter whether the flow path throttling device 19 is opened, and the effect of reducing the pressure loss of the flow path is achieved through the first control valve 18.

After heat exchange in the outdoor heat exchangers 4-1 and 4-2, the refrigerant is condensed to release heat and becomes liquid refrigerant, and then the refrigerant enters the indoor side through the liquid pipe throttling devices 6-1 and 6-2.

The refrigerant entering the indoor side is throttled by the settling devices 10-1 and 10-2, enters the indoor heat exchangers 11-1 and 11-2 to be evaporated and absorbed heat and is changed into a gaseous state, and the refrigerant coming out of the indoor heat exchangers 11-1 and 11-2 enters the gas-liquid separator 14 through the first extension pipe 12, the gas side stop valve 13 and the E and S of the flow path switching device 3 and is finally sucked into the compressor 1 to be compressed, so that the refrigeration cycle is completed.

The refrigerant flow in the normal cooling operation mode of the outdoor unit W1 is in the direction indicated by the broken line arrow in fig. 1.

The outdoor fans 5-1 and 5-2 are always turned 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 4-1 or 4-2 needs defrosting, the compressor 1 firstly reduces the frequency or directly stops, and the indoor fans, the outdoor fans 5-1 and 5-2 in the outdoor unit W1 and the outdoor fan in the outdoor unit module W2 stop running.

The air conditioner is operated in a normal cooling operation mode, all the outdoor heat exchangers 4-1 and 4-2 are used as condensers to start defrosting, namely heating of all indoor units is stopped and defrosting is carried out on all the outdoor heat exchangers.

After the defrosting is completed, the air conditioner re-enters 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 of the sound is severe.

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.

When 2 outdoor heat exchangers of the outdoor unit W1 all need defrosting, the 2 outdoor heat exchangers to be defrosted execute the alternate defrosting operation mode.

In some embodiments, referring to fig. 1, the example of the alternate defrosting of the outdoor heat exchangers 4-1 and 4-2 in the outdoor unit W1 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 4-1 and 4-2 meet defrosting conditions, if so, entering S4, and if not, continuing to execute a normal heating operation mode of S2.

The defrosting condition can be judged according to the existing judgment basis, for example, the running time of the compressor 1 and the temperature difference between the ambient temperature and the outdoor unit coil temperature are taken as the criterion.

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

The outdoor heat exchangers 4-1 and 4-2 are alternately defrosted according to the frosting amount of the outdoor heat exchangers 4-1 and 4-2 to be defrosted.

The outdoor heat exchangers 4-1 and 4-2 can be sequentially defrosted according to the sequence of the frost formation amount from large to small.

The judgment of the frosting amount can be performed by detecting an index indicative of the frosting amount by a detecting means (not shown), for example, at least one of the heating capacity of the outdoor heat exchangers 4-1 and 4-2, 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 4-2 and 4-2 according to the variation 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.

If the frosting amount of the outdoor heat exchanger 4-1 is larger than that of the outdoor heat exchanger 4-2, the outdoor heat exchanger 4-1 should be defrosted first to avoid that the normal operation of the outdoor heat exchanger 4-1 is influenced by excessive frosting. The outdoor heat exchanger 4-2 is in a normal heating operation mode at this time.

That is, the outdoor heat exchanger 4-1 is performed as a defrosting heat exchanger, and the outdoor heat exchanger 4-2 is performed as an evaporator.

After the defrosting of the outdoor heat exchanger 4-1 is completed and the normal heating operation mode is entered, the outdoor heat exchanger 4-2 is defrosted.

That is, the switching of the outdoor heat exchanger 4-2 is performed as a defrosting heat exchanger, and the outdoor heat exchanger 4-1 is performed as an evaporator.

After the outdoor heat exchangers 4-1 and 4-2 are alternately defrosted for many times, a reverse defrosting operation mode can be selected to completely defrost the outdoor heat exchangers 4-1 and 4-2. Of course, the reverse defrost mode of operation may be selected under other conditions.

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

S41: the flow path switching device 3 is controlled to be opened (i.e., powered on), the flow path throttling device 19, the first control valve 18, and the defrosting switching device 21/20 are controlled to allow a part of the refrigerant discharged from the compressor 1 to enter the defrosting heat exchanger through the flow path throttling device 19 and the defrosting switching device 21/20, the pipe throttling device communicated with the defrosting heat exchanger is cut off, the throttling device is controlled to be opened, and the remaining outdoor heat exchanger is operated as an evaporator.

The outdoor heat exchanger 4-1 in the outdoor unit module is used as a defrosting heat exchanger to execute, and a defrosting process is started, and the outdoor heat exchanger 4-2 is used as an evaporator to execute, so that a normal heating operation process is kept.

The flow path switching device 3 is kept in the power-on open state, the control flow path throttling device 19 is opened and the first control valve 18 is closed, the defrost switching device 21 is powered off and closed, the defrost switching device 20 is powered on and opened, the outdoor fan 5-1 is turned off, the liquid pipe throttling device 6-1 is turned off, the throttling device 28 is opened, and the remaining devices are kept in the same state as in the normal heating operation mode.

The flow path switching device 3, the flow path adjusting device 19, the first control valve 18, the defrosting switching device 20/21, the outdoor fan 5-1, the pipe throttling device 6-1, and the throttling device 28 are all devices in the outdoor unit W1.

Referring to fig. 1 again, solid arrows indicate the refrigerant flow direction during the defrosting process of the outdoor heat exchanger 4-1.

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 through the check valve 2.

A part of high-temperature and high-pressure refrigerant enters the indoor heat exchangers 11-1 and 11-2 through the flow path switching device 3D and E, the gas side stop valve 13 and the first extension pipe 12, is condensed and releases heat after heat exchange in the indoor heat exchangers 11-1 and 11-2 to form liquid refrigerant, and then enters the liquid pipe throttling device 6-2 through the indoor machine side throttling devices 10-1 and 10-2, the second extension pipe 9 and the liquid side stop valve 8.

The other part of the high-temperature and high-pressure refrigerant is throttled to a proper pressure by the flow path throttling device 19 and then enters the defrosting switching device 21D and C to enter the outdoor heat exchanger 4-1 for heat exchange and defrosting, the refrigerant which is subjected to heat exchange from the outdoor heat exchanger 4-1 is throttled by the throttling device 28 and then is merged with the refrigerant which is discharged from the liquid pipe throttling device 6-2, then enters the outdoor heat exchanger 4-2 for evaporation and heat absorption to become a gas state, and the refrigerant which is discharged from the outdoor heat exchanger 4-2 enters the gas-liquid separator 14 by the defrosting switching device 20C and S.

When one outdoor heat exchanger in the outdoor unit is defrosted, aiming at the defrosting heat exchanger such as the outdoor heat exchanger 4-1, the opening degree of the throttling device 28 is controlled and adjusted according to the outlet supercooling degree of the outdoor heat exchanger 4-1 and the target outlet supercooling degree range, so that the outlet supercooling degree of the outdoor heat exchanger 4-1 tends to be maintained in the target outlet supercooling degree range; according to the defrosting pressure and the target defrosting pressure range, the opening degree of the flow path throttling device 19 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.

When defrosting the outdoor heat exchanger 4-1, the opening degrees of the throttle device 28 and the flow path throttle device 19 are controlled.

Before entering the defrosting process, it is necessary to set the initial opening degrees of the flow path throttling device 19 and the defrosting time throttling device 28.

For example, since both the pre-defrosting flow path throttling device 19 and the throttling device 28 are off, it is necessary to set an initial opening degree (for example, fully open) of the flow path throttling device 19 and an initial opening degree (for example, fully open) of the throttling device 28 during defrosting before defrosting.

S1': the target outlet supercooling degree range of the outdoor heat exchanger 4-1 and the target defrosting pressure range are set.

In the present application, there is a range for the target outlet supercooling degree Te1sco, for example, 0 ℃ C. ltoreq. Te1 sco. ltoreq.10 ℃.

A target outlet supercooling degree range (Te 1sco- λ, Te1sco + λ) is set, for example, 0 ℃ < λ < 3 ℃ based on the target outlet supercooling degree Te1 sco.

In the present application, the target defrosting pressure Pfo is a function Pfo = f (TW1) of the ambient temperature TW1, and the function Pfo = f (TW1) may be a preset function determined when the air conditioner is commissioned.

When the ambient temperature sensor detects the ambient temperature TW1, the target defrosting pressure Pfo can be known from the function f (TW 1).

Based on the target defrost pressure Pfo, a target defrost pressure range (Pfo- δ, Pfo + δ) is set, for example, 0MPW1 < δ < 0.5MPW 1.

S2': and calculating the supercooling Te1sco of the outlet of the outdoor heat exchanger 4-1.

The outlet supercooling degree Te1sc of the outdoor heat exchanger 4-1 is calculated by the defrosting pressure Pf (detected by the pressure sensor 221) and the outlet temperature Te1 (detected by the temperature sensor 231) of the outdoor heat exchanger 4-1.

That is, Te1sc = Tec-Te1, where Tec is the corresponding saturation temperature at the defrost pressure Pf, which can be obtained by prior art queries.

S3': comparing whether the outlet supercooling degree Te1sc is in the target outlet supercooling degree range;

s31': if the outlet supercooling degree Te1sc is within the target outlet supercooling degree range, keeping the opening degree of the throttling device 28 and executing to S4'; if not, the opening degree of the throttle device 28 is adjusted, and the process proceeds to S4'.

The process of specifically adjusting the opening degree of the throttle device 28 is described below.

S32': if the outlet supercooling degree Te1sc is greater than the upper limit value of the target outlet supercooling degree range, the opening degree of the throttle device 28 is increased by one adjustment step number, and execution is carried out to S4'.

That is, the next opening degree EV28(n +1) = EV28(n) - Δ EV28 of the throttle device 28, where Δ EV28 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 degree.

S33': if the outlet supercooling degree Te1sc is smaller than the lower limit value of the target outlet supercooling degree range, the opening degree of the throttling means 28 is decreased by one adjustment step number, and execution is carried out to S4'.

That is, the next opening EV28(n +1) = EV28(n) + Δ EV28 of the throttle device 28, where Δ EV28 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.

S4': whether the defrosting pressure Pf is within the target defrosting pressure range is compared, if so, the opening degree of the flow path throttling device 19 is maintained, and execution proceeds to S42, and if not, the opening degree of the flow path throttling device 19 is adjusted, and execution proceeds to S42.

The process of specifically adjusting the opening degree of the flow path throttling device 19 is described below.

S41': if the defrosting pressure Pf is within the target defrosting pressure range, the opening degree of the flow path throttling device 19 is maintained, and the process 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 flow path throttling device 19 is decreased by one adjustment step number, and execution proceeds to S42.

That is, the next opening degree EV19(n +1) = EV19(n) - Δ EV19 of the flow path throttling device 19, where Δ EV19 is the number of adjustment steps, where the number of adjustment steps can be selected to be 0.1% to 10% pls (i.e., the number of steps) of the total opening degree.

S43': if the defrosting pressure Pf is less than the lower limit value of the target defrosting pressure range, the opening degree of the flow path throttling device 19 is increased by one adjustment step number, and execution proceeds to S42.

That is, the next opening degree EV19(n +1) = EV19(n) + Δ EV19 of the flow path throttling device 19, where Δ EV19 is the number of adjustment steps, where the number of adjustment steps can be selected to be 0.1% to 10% pls (i.e., the number of steps) of the total opening degree.

S42: it is determined whether or not defrosting is completed, and if so, the defrosting process is exited, otherwise, the flow returns to S2', and the opening degrees of the throttle device 28 and the flow path throttle device 19 are adjusted again.

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 4-1 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 4-1 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 adjusting the opening degrees of the throttle device 28 and the flow path throttle device 19 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'.

And after the defrosting of the outdoor heat exchanger 4-1 is finished, the defrosting process is quitted, and then the normal heating operation process is carried out.

The outdoor heat exchanger 4-1 exits the defrosting process and enters a normal heating operation process, which at least comprises the following steps:

(1) controlling the defrosting switching device 21 to be powered on and opened, and enabling the gas side of the defrosting heat exchanger 4-1 to be communicated with the gas-liquid separator 14;

(2) opening an outdoor fan 5-1;

(3) opening the pipe throttling device 6-1;

as for the throttling device 28, it is possible to select an arbitrary opening degree (preferably, close) when the outdoor heat exchanger 4-1 enters the ordinary heating operation process.

As for the flow path throttling means 19, if the outdoor heat exchanger 4-1 exits the defrosting process without defrosting the other outdoor heat exchangers, and thereafter enters the normal heating operation process, the flow path throttling means 19 may be in an arbitrary opening degree.

During defrosting, the indoor side throttling devices 10-1 and 10-2 maintain control before defrosting, the throttling device 6-2 maintains normal heating control, namely, the outlet superheat degree Ts2 of the outdoor heat exchanger 4-2 is controlled, namely, the temperature sensor 233 detects the exhaust temperature Td2, the pressure sensor 222 detects the exhaust pressure Pd2, the outlet superheat degree Ts2 of the outdoor heat exchanger 4-2 is the difference between the exhaust temperature Td2 and the saturation temperature corresponding to the exhaust pressure Pd2, and the outlet superheat degree Ts2 is controlled within 0-2 ℃.

Similarly, when the outdoor heat exchanger 4-1 is out of defrosting and the outdoor heat exchanger 4-2 is defrosting, the throttling device 6-1 is also used for controlling the outlet superheat degree of the outdoor heat exchanger 4-1 within 0-2 ℃.

Thereafter, the outdoor heat exchanger 4-2 serves as a defrosting heat exchanger to enter a defrosting process, and the outdoor heat exchanger 4-1 serves as an evaporator to maintain a normal heating operation process.

The flow path switching device 3 is kept in the open power-on state, the flow path throttling device 19 is kept open and the first control valve 18 is closed, the defrosting switching device 20 is closed by controlling the power-off, the throttling device 28 is opened, the outdoor fan 5-2 and the liquid pipe throttling device 6-2 are closed, and the rest devices are kept in the same state as in the normal heating operation mode.

The defrosting process of the outdoor heat exchanger 4-2 is referred to as the defrosting process of the outdoor heat exchanger 4-1.

When the outdoor heat exchanger 4-2 is defrosted, the outdoor heat exchanger 4-1 performs a normal heating operation process.

[ 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 path switching device and flows into the indoor heat exchanger 11-1/11-2 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 11-1/11-2, and the other end is connected to a gas-liquid separator (for example, the gas-liquid separator 14), specifically, referring to fig. 1, the other end is communicated with the gas-liquid separator 14 through the extension pipe 26 and the gas-side shutoff valve 27.

The two-regulation and the three-regulation are realized by switching the first switching valve a and the second switching valve b.

Referring to fig. 3, the air conditioner has a main cooling operation mode and a 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 11-1 serves as an evaporator (i.e., the indoor heat exchanger 11-1 cools down) and the indoor heat exchanger 11-2 serves as a condenser (i.e., the indoor heat exchanger 11-2 heats up).

Referring to fig. 3, the flow path switching device 3 in the outdoor unit W1 is electrically powered on, the flow path throttling device 19 is at an arbitrary opening degree, the first control valve 18 is opened, the defrosting switching devices 21 and 20 are both electrically powered off and closed, the liquid duct throttling devices 6-1 and 6-2 are both opened, the outdoor fans 5-1 and 5-2 are both opened, the throttling device 28 is at an arbitrary opening degree, the first switching valve a (i.e., the first switching valve 24 a) connected to the indoor heat exchanger 11-1 is controlled to be closed and the second switching valve b (i.e., the second switching valve 24 b) is controlled to be opened, the first switching valve a (i.e., the first switching valve 25 a) connected to the indoor heat exchanger 11-2 is controlled to be opened and the second switching valve b (i.e., the second switching valve 25 b.

Wherein D and C and E and S in the defrost switching devices 21 and 20 are communicated.

The flow path switching device 3 is powered on and is opened, 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, and the refrigerant is divided into two parts after passing through the one-way valve 2.

A part of the high-temperature and high-pressure refrigerant enters the outdoor heat exchangers 4-1 and 4-2 through the first control valve 18 into D and C of the defrost switching devices 21 and 20. After heat exchange in the outdoor heat exchangers 4-1 and 4-2, the refrigerant is condensed and released to become liquid refrigerant, and then the refrigerant flows to the liquid side stop valve 8 and the second extension pipe 9 through the liquid pipe throttling devices 6-1 and 6-2.

The other part of high-temperature and high-pressure refrigerant enters the indoor heat exchanger 11-2 through the gas side stop valve 13, the first extension pipe 12 and the first switching valve 25a through the flow path switching device 3, is subjected to internal heat exchange, is condensed and releases heat to form liquid refrigerant, then the refrigerant passes through the indoor machine side throttling device 10-2, is merged with the refrigerant from the outdoor side through the liquid side stop valve 8 and the second extension pipe 9, enters the indoor machine side throttling device 10-1, is throttled and depressurized to be in a gas-liquid state.

Then, the refrigerant enters the indoor heat exchanger 11-1 to be evaporated and absorbed heat, turns into a gaseous state, enters the gas-liquid separator 14 through the second switching valve 24b, the extension pipe 26, and the gas-side shutoff valve 27, 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 11-1 serves as a condenser (i.e., the indoor heat exchanger 11-1 heats) and the indoor heat exchanger 11-2 serves as an evaporator (i.e., the indoor heat exchanger 11-2 cools).

Referring to fig. 3, the flow path switching device 3 in the outdoor unit module is electrically opened, the flow path throttling device 19 is at an arbitrary opening degree, the first control valve 18 is selectively opened or closed (preferably closed), the defrosting switching devices 21 and 20 are electrically connected, the pipe throttling devices 6-1 and 6-2 are opened, the outdoor fans 5-1 and 5-2 are opened, the throttling device 28 is at an arbitrary opening degree, the first switching valve 24a is controlled to be opened and the second switching valve 24b is controlled to be closed, the first switching valve 25a is controlled to be closed and the second switching valve 25b is controlled to be opened.

Wherein D and E and C and S in the defrost switching devices 21 and 20 are communicated.

The flow path switching device 3 is electrically opened, D and E are communicated, C and S are communicated, the compressor 1 compresses low-temperature and low-pressure refrigerant into a high-temperature and high-pressure state, the refrigerant enters the indoor heat exchanger 11-1 through the check valve 2, D and E of the flow path switching device 3, the gas side stop valve 13, the first extension pipe 12 and the first switching valve 24a to be subjected to internal heat exchange, then is condensed and releases heat to form liquid refrigerant, and then the refrigerant flows out through the indoor machine side throttling device 10-1 and is divided into two parts.

And a part of the refrigerant enters the liquid pipe throttling devices 6-1 and 6-2 through the second extension pipe 9 and the liquid side stop valve 8 to be throttled to a low-temperature low-pressure gas-liquid two state, then enters the outdoor heat exchangers 4-1 and 4-2 to be evaporated and absorbed, and is changed into a gas state, and the refrigerant coming out of the outdoor heat exchangers 4-1 and 4-2 flows out through C and S of the defrosting switching devices 21 and 20.

The other part is throttled and depressurized by the indoor unit-side throttle device 10-2 to enter the indoor heat exchanger 11-2 to be evaporated and absorbed heat, and is changed into a gas state, and then the gas state is merged with the refrigerant flowing out through the defrosting switching devices 21 and 20 as described above through the second switching valve 25b, the extension pipe 26, and the gas-side stop valve 27, and then enters the gas-liquid separator 14, and finally is sucked into the compressor 1 to be compressed, thereby completing the main heating cycle.

In the case of the three-pipe heat recovery function, referring to fig. 3, at least the first switching valve 24a and the first switching valve 25a may be controlled to be closed when the defrosting is performed by the rotation.

That is, (1) the first switching valve 24a and the first switching valve 25a are controlled to be closed, and the second switching valve 24b and the second switching valve 25b are controlled to be closed; (2) the first switching valve 24a and the first switching valve 25a are controlled to be closed, and the second switching valve 24b and the second switching valve 25b are controlled to be closed.

The remaining devices remain the same as in the alternate defrost mode of operation described above.

And controls the first switching valves 24a and 25a to be closed and the second switching valves 24b and 25b to be closed in the normal heating operation mode and the normal cooling operation mode.

[ separation of wind field ]

Since the corresponding outdoor fan 5-2 of the outdoor heat exchanger 4-2 is kept in operation when the outdoor heat exchanger 4-1 is defrosted, in order to avoid the situation that the outdoor heat exchanger 4-1 cannot be defrosted effectively due to the wind field generated by the outdoor fan 5-2 blowing through the outdoor heat exchanger 4-1, a separating device 101 for separating the wind field is provided in the present application (see patent document with application number 262610279447.2 entitled "outdoor unit of air conditioner").

In the present application, the outdoor fans 5-1 and 5-2 are independently controlled by the control device, respectively, and the outdoor heat exchanger 4-1 and the outdoor fan 5-1 form a first wind field, and the outdoor heat exchanger 4-2 and the outdoor fan 5-2 form a second wind field, and the partition device 101 is used to separate the first wind field and the second wind field.

That is, it does not blow wind to the outdoor heat exchanger 4-2 when the outdoor fan 5-1 is operated and the outdoor fan 5-2 is not operated, and it does not blow wind to the outdoor heat exchanger 4-1 when the outdoor fan 5-2 is operated and the outdoor fan 5-1 is not operated.

Thus, when the outdoor heat exchanger 4-1 performs defrosting, since the partition 101 separates the first wind field and the second wind field, the first wind field is not affected even if the outdoor fan 5-2 is still operated.

Therefore, the situation that the air blows over the surface of the outdoor heat exchanger 4-1 when defrosting is carried out is effectively avoided, the situation that the defrosting cannot be effectively carried out due to overlarge condensation load when the outdoor temperature is low is further prevented, and uninterrupted heating of a full-temperature area can be realized.

In addition, when the outdoor fan 5-1 stops running (namely the outdoor heat exchanger 4-1 is defrosting), the rotating speed of the outdoor fan 5-2 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 4-1 exits the defrosting process and enters a normal heating operation process, the outdoor fan 5-1 is correspondingly turned on and the outdoor fan 5-2 of the outdoor heat exchanger 4-2 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.