WO2023116854A1 - Control method for three-pipe type multi-split air conditioning assembly - Google Patents

Abstract

The invention belongs to the technical field of air conditioners, and specifically provides a control method for a three-pipe type multi-split air conditioning assembly. The invention aims to solve the problem of poor operation efficiency caused by the poor control logic of existing three-pipeline multi-split air conditioning assemblies. In order to achieve this purpose, the control method for a three-pipe type multi-split air conditioning assembly comprises: acquiring an outdoor ambient temperature, a refrigeration ratio of a three-pipe type multi-split air conditioning assembly and the current operation mode of an outdoor unit of the three-pipe type multi-split air conditioning assembly; on the basis of the outdoor ambient temperature, the refrigeration ratio, and the current operation mode of the outdoor unit, selectively switching the operation mode of the outdoor unit. The operation mode of the outdoor unit can be adjusted in a timely manner in accordance with different use requirements. Thus, the operation mode of the outdoor unit is always able to be adapted to the actual heat exchange requirements, effectively improving the heat exchange efficiency of the three-pipe type multi-split air conditioning assembly.

Description

Control method for three-pipe multi-connected air-conditioning unit

This application claims the priority of the Chinese patent application CN202111601974.1 filed on December 24, 2021, the invention title is "Control method for three-pipe multi-connected air-conditioning unit", the entire content of the above-mentioned Chinese patent application is incorporated by reference included in this application.

technical field

The invention belongs to the technical field of air conditioning, and specifically provides a control method for a three-pipe multi-connected air conditioning unit.

Background technique

Most of the existing multi-connected air-conditioning units are two-pipe multi-connected air-conditioning units, and all the indoor units can only operate in the same mode. If there is an indoor unit running in the cooling mode, the outdoor unit needs to be started in accordance with the cooling mode. In this case In this case, the outdoor unit can only keep the cooling mode all the time, and the other indoor units can only operate in the cooling mode, which cannot meet the cooling and heating needs at the same time; The operating mode of the indoor unit can be switched to the heating mode, and the other indoor units can also operate in the heating mode accordingly.

In order to make the same multi-connected air-conditioning unit meet the cooling and heating demands of different indoor units at the same time, a three-pipe multi-connected air-conditioning unit came into being. The three-pipe multi-connected air-conditioning unit can simultaneously meet the different heat transfer requirements of different indoor units. In order to meet the heat exchange needs of different users to the greatest extent. However, the operating mode of the outdoor unit of the existing three-pipe multi-connected air conditioner unit is usually determined by the operating mode of the first opened indoor unit, that is, the first opened indoor unit needs to operate in cooling mode, and the outdoor unit Correspondingly, it operates in the main mode of cooling; or, the operating mode of the outdoor unit is determined according to the magnitude relationship between the number of indoor units operating in the cooling mode and the number of indoor units operating in the heating mode. However, these simple control logics are difficult to adapt to complex and changeable internal unit operating conditions, which leads to the problem of poor operating efficiency of the existing three-pipeline multi-connected air-conditioning units.

Correspondingly, there is a need in the art for a new control method for a three-pipe multi-connected air-conditioning unit to solve the above problems.

Contents of the invention

The present invention aims to solve the above-mentioned technical problems, that is, to solve the problem that the existing three-pipeline multi-connected air-conditioning units have poor control logic and thus lead to poor operating efficiency.

The present invention provides a control method for a three-pipe multi-connected air conditioner unit, the control method comprising:

Obtaining the outdoor ambient temperature, the cooling ratio of the three-pipe multi-connected air conditioner unit and the current operating mode of the outdoor unit;

The operation mode of the outdoor unit is selectively switched according to the outdoor ambient temperature, the cooling ratio and the current operation mode.

In the preferred technical solution of the above control method, the step of "selectively switching the operation mode of the outdoor unit according to the outdoor ambient temperature, the cooling ratio and the current operation mode" includes:

When the outdoor unit is operating in the cooling main mode, selectively switch the operation mode of the outdoor unit to cooling according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio. Hot subject mode.

In the preferred technical solution of the above control method, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit to the heating main mode" steps include:

If the outdoor ambient temperature is less than or equal to the first preset temperature and greater than or equal to the second preset temperature, and the cooling ratio is less than or equal to the first preset ratio, switch the operation mode of the outdoor unit to Heating main mode.

In the preferred technical solution of the above control method, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit to the heating main mode" steps also include:

If the outdoor ambient temperature is less than the second preset temperature and greater than or equal to a third preset temperature, and the cooling ratio is less than or equal to the second preset ratio, switch the operation mode of the outdoor unit to Heating main mode;

Wherein, the second preset ratio is greater than the first preset ratio.

In the preferred technical solution of the above control method, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit to the heating main mode" steps also include:

If the outdoor ambient temperature is less than the third preset temperature and the cooling ratio is less than or equal to the third preset ratio, switch the operation mode of the outdoor unit to the heating main mode;

Wherein, the third preset ratio is greater than the second preset ratio.

In the preferred technical solution of the above control method, the step of "selectively switching the operation mode of the outdoor unit according to the outdoor ambient temperature, the cooling ratio and the current operation mode" further includes:

When the outdoor unit is operating in the heating main mode, according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operating mode of the outdoor unit to Cooling main mode.

In the preferred technical solution of the above control method, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit to the cooling main mode ” steps include:

If the outdoor ambient temperature is greater than or equal to the second preset temperature, and the cooling ratio is greater than a fourth preset ratio, the operation mode of the outdoor unit is switched to a cooling main mode.

In the preferred technical solution of the above control method, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit to the cooling main mode " steps also include:

If the outdoor ambient temperature is less than the second preset temperature and greater than or equal to the third preset temperature, and the cooling ratio is greater than a fifth preset ratio, switch the operation mode of the outdoor unit to Cooling main mode;

Wherein, the fifth preset ratio is greater than the fourth preset ratio.

In the preferred technical solution of the above control method, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit to the cooling main mode " steps also include:

If the outdoor ambient temperature is less than the third preset temperature and greater than or equal to the fourth preset temperature, and the cooling ratio is greater than the sixth preset ratio, switch the operation mode of the outdoor unit to cooling main model;

Wherein, the sixth preset ratio is greater than the fifth preset ratio.

In the preferred technical solution of the above control method, the control method also includes:

When the number of indoor units operating in cooling mode is equal to the number of indoor units operating in heating mode, if the sum of the number of indoor units operating in cooling mode is also equal to the sum of the number of indoor units operating in heating mode, The heat exchanger of the outdoor unit is then turned off, so that the outdoor unit operates in a heat recovery mode.

In the case of adopting the above technical solution, the control method for the three-pipe multi-connected air-conditioning unit of the present invention includes: obtaining the outdoor ambient temperature, the cooling ratio of the three-pipe multi-connected air-conditioning unit and the current temperature of the outdoor unit Operation mode: selectively switch the operation mode of the outdoor unit according to the outdoor ambient temperature, the cooling ratio and the current operation mode. The present invention can selectively switch the operation mode of the outdoor unit according to the outdoor ambient temperature, the cooling ratio and the current operation mode, so that the operation mode of the outdoor unit can be adjusted in time according to different usage requirements, Therefore, the operation mode of the outdoor unit can always be adapted to the actual heat exchange demand, thereby effectively improving the heat exchange efficiency of the three-pipe multi-connected air conditioner unit.

Description of drawings

Describe preferred embodiment of the present invention below in conjunction with accompanying drawing, in the accompanying drawing:

Fig. 1 is a system diagram when the outdoor unit of the three-pipe multi-connected air-conditioning unit of the present invention operates in the cooling main mode;

Fig. 2 is a system diagram when the outdoor unit of the three-pipe multi-connected air conditioner unit of the present invention operates in the heating main mode;

Fig. 3 is a system diagram of the outdoor unit operating in the heat recovery mode of the three-pipe multi-connected air conditioner unit of the present invention;

Fig. 4 is the flow chart of main steps of the control method of the present invention;

Fig. 5 is a flowchart of specific steps of the first preferred embodiment of the present invention;

Fig. 6 is a flow chart of specific steps of the second preferred embodiment of the present invention.

Detailed ways

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present invention, and are not intended to limit the protection scope of the present invention. Those skilled in the art can make adjustments as needed so as to adapt to specific applications.

It should be noted that, in the description of this preferred embodiment, terms such as “inner” and “outer” indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for convenience of description. It is not intended to indicate or imply that the device or element must have a particular orientation, be constructed in a particular orientation, or operate in a particular orientation, and thus should not be construed as limiting the invention. In addition, in the description of the present invention, unless otherwise clearly stipulated and limited, the term "connected" should be understood in a broad sense, for example, it may be directly connected, indirectly connected through an intermediary, or internally connected between two elements. .

In addition, the terms "first", "second", "third", "fourth", "fifth", and "sixth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meanings of the above terms in the present invention according to specific situations. Although the various steps of the control method of the present invention are described in a specific order in this application, these orders are not limiting, and those skilled in the art can perform them in different orders without departing from the basic principle of the present invention the steps.

First refer to Figures 1 to 3, wherein, Figure 1 is a system diagram of the outdoor unit of the three-pipe multi-connected air conditioner unit of the present invention when the outdoor unit is operating in the cooling main mode; Figure 2 is the outdoor unit of the three-pipe multi-connected air conditioner unit of the present invention System diagram when the heating main mode is running; Fig. 3 is a system diagram when the outdoor unit of the three-pipe multi-connected air conditioner unit of the present invention is running in the heat recovery mode. Specifically, as shown in Figures 1 to 3, the arrows in the figures show the flow direction of the refrigerant. The three-pipe multi-connected air conditioner unit of the present invention includes an external unit 1 and an external unit 2 arranged in parallel and an internal unit arranged in parallel. 1. Inner unit 2, inner unit 3, and inner unit 4. Of course, the present invention does not impose any restrictions on the number of specific installations of the outer unit and the inner unit, and technicians can set them by themselves according to actual use requirements. Each external unit includes two heat exchangers, that is, an upper heat exchanger and a lower heat exchanger, and an electronic expansion valve LEVA1 is installed on the refrigerant branch line with the upper heat An electronic expansion valve LEVA2 is correspondingly arranged on the branch to control the on-off state of the corresponding refrigerant branch and the flow rate of the refrigerant. In addition, three four-way valves are correspondingly arranged in each external unit, and the circulation of the refrigerant in the corresponding external unit can be controlled by controlling the connection state of the three four-way valves. In addition, each indoor unit includes an indoor heat exchanger. Of course, this is not limiting. There may also be an indoor unit including multiple indoor heat exchangers; There is a valve box (that is, the structure shown in the box below the indoor unit), and each valve box includes two refrigerant branch circuits arranged in parallel, and these two refrigerant branch circuits are respectively connected to the high-pressure air pipe of the external unit and the The low-pressure gas pipes are connected, wherein the refrigerant branch connected to the high-pressure gas pipe is provided with a solenoid valve EEVli, and the refrigerant branch connected to the low-pressure gas pipe is provided with a solenoid valve EEVlo. One end of the internal unit is connected to the two refrigerant branches. The other end is connected to the liquid pipe, and the circulation of the refrigerant in the corresponding internal unit can be controlled by opening the electromagnetic valve EEVlo and the electromagnetic valve EEVli, thereby controlling the heat exchange state of the corresponding internal unit. It should be noted that the present invention does not impose any restrictions on the specific structure of the three-pipe multi-connected air-conditioning unit, and technicians can set it according to actual use requirements; this specific structure of the three-pipe multi-connected air-conditioning unit The change does not deviate from the basic principle of the present invention, and belongs to the protection scope of the present invention.

Further, the three-pipe multi-connected air conditioner unit of the present invention also includes an outdoor ambient temperature sensor and a controller, the outdoor ambient temperature sensor can detect the outdoor ambient temperature, and the controller can obtain the outdoor ambient temperature The detection data of the sensor, and the controller can also control the operation status of the three-pipe multi-connected air conditioner unit, for example, control the operation mode of the outdoor unit, control the operation mode of the indoor unit, and so on. Those skilled in the art can understand that the present invention does not impose any restrictions on the specific structure and model of the controller, and the controller can be the original controller of the three-pipe multi-connected air-conditioning unit, or it can be It is a controller set separately for implementing the control method of the present invention, and technicians can set the structure and model of the controller according to actual use requirements.

Referring next to Fig. 4, this figure is a flow chart of the main steps of the control method of the present invention. As shown in Figure 4, based on the three-pipe multi-connected air-conditioning unit described in the above embodiment, the control method of the present invention mainly includes the following steps:

S1: Obtain the outdoor ambient temperature, the cooling ratio of the three-pipe multi-connected air conditioner unit and the current operating mode of the outdoor unit;

S2: Selectively switch the operation mode of the outdoor unit according to the outdoor ambient temperature, cooling ratio and current operation mode.

In step S1, the controller can obtain the outdoor ambient temperature through the outdoor ambient temperature sensor. Of course, this acquisition method is not limiting, and technicians can also use other methods to obtain the outdoor ambient temperature, for example , obtained via the Internet. In addition, in this preferred embodiment, the refrigeration ratio of the three-pipe multi-connected air conditioner unit can be calculated by the following formula:

Cooling ratio = Σ cooling Thermo ON rated capacity / (Σ cooling Thermo ON rated capacity + Σ heating Thermo ON rated capacity + Σ heating Thermo OFF rated capacity × G)

It should be noted that the present invention does not set any limitation on the specific value of the correction coefficient G in the above formula, and technicians can set it according to different models and usage conditions, which is not restrictive. Of course, the above calculation method is not limiting, and technicians can also set the calculation method of the cooling ratio according to actual usage requirements.

Next, in step S2, the controller can selectively switch the operation mode of the outdoor unit according to the outdoor ambient temperature, the cooling ratio and the current operation mode. It should be noted that the present invention does not impose any restrictions on the specific judgment conditions, and technicians can set them according to actual use requirements, as long as the basic parameters used in the judgment process include the outdoor ambient temperature, the three-pipe multi-connected air conditioner The cooling ratio of the unit and the current operating mode of the outdoor unit should belong to the protection scope of the present invention.

Referring next to Fig. 5, this figure is a flow chart of specific steps of the first preferred embodiment of the present invention. As shown in Figure 5, based on the three-pipe multi-connected air-conditioning unit described in the above-mentioned preferred embodiment, the first preferred embodiment of the control method of the present invention specifically includes the following steps:

S101: Obtain the outdoor ambient temperature, the cooling ratio of the three-pipe multi-connected air conditioner unit and the current operating mode of the outdoor unit;

S102: When the outdoor unit is operating in the cooling main mode, selectively switch the operation mode of the outdoor unit to the heating main mode according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio;

S103: If the outdoor ambient temperature is less than or equal to the first preset temperature and greater than or equal to the second preset temperature, and the cooling ratio is less than or equal to the first preset ratio, switch the operation mode of the outdoor unit to the heating main mode ;

S104: If the outdoor ambient temperature is less than the second preset temperature and greater than or equal to the third preset temperature, and the cooling ratio is less than or equal to the second preset ratio, switch the operation mode of the outdoor unit to the heating main mode;

S105: If the outdoor ambient temperature is less than the third preset temperature and the cooling ratio is less than or equal to the third preset ratio, switch the operation mode of the outdoor unit to the heating main mode.

It should be noted that the present invention does not impose any restrictions on the specific values of the first preset temperature, the second preset temperature, and the third preset temperature, and technicians can set them by themselves according to actual use requirements. As long as the three satisfy the relationship that the first preset temperature is greater than the second preset temperature and is greater than the third preset temperature.

In addition, it should be noted that the present invention does not impose any restrictions on the specific values of the first preset ratio, the second preset ratio, and the third preset ratio, and technicians can adjust the values according to actual use requirements. setting, as long as the three satisfy the relationship that the first preset ratio is smaller than the second preset ratio and smaller than the third preset ratio.

In addition, when the outdoor unit is operating in the cooling main mode, if the judgment result of the controller does not satisfy the above three conditions, the outdoor unit can continue to maintain the cooling main mode without switching.

As a specific example, refer to Figures 1 and 2, the flow of the refrigerant is shown in the figure. In Figure 1, the indoor unit 1 and the indoor unit 4 operate in the cooling mode, and the indoor units 2 and 3 operate in the heating mode. The cooling ratio of the three-pipe multi-connected air conditioner unit is 75%. At this time, the outdoor The operating mode of the unit is the cooling main mode; the indoor unit 1 and the indoor unit 4 in Figure 2 operate in the heating mode, and the indoor units 2 and 3 operate in the cooling mode. The cooling ratio is 25%. According to the judgment method provided by the present invention, the operation mode of the outdoor unit should be switched from the cooling main mode to the heating main mode at this time. In this case, the actions of each valve and the mode of each indoor unit are as follows :

External machine mode	Cooling Master Mode	Heating main mode
4WV1	OFF	ON
4WV2	OFF	ON
4WV3	ON	ON
upper heat exchanger	Refrigeration	Heating
lower heat exchanger	Refrigeration	Heating
LEVA1	fully open	superheat control
LEVA2	fully open	superheat control
Internal machine, valve box mode	Inner unit, valve box	Inner unit, valve box
Indoor unit 13HP	Refrigeration	Heating
Indoor unit 21HP	Heating	Refrigeration
Indoor unit 31HP	Heating	Refrigeration
Indoor unit 43HP	Refrigeration	Heating

Referring next to Fig. 6, this figure is a flow chart of specific steps of the second preferred embodiment of the present invention. As shown in Figure 6, based on the three-pipe multi-connected air-conditioning unit described in the above-mentioned preferred embodiment, the second preferred embodiment of the control method of the present invention specifically includes the following steps:

S201: Obtain the outdoor ambient temperature, the cooling ratio of the three-pipe multi-connected air conditioner unit and the current operating mode of the outdoor unit;

S202: When the outdoor unit is operating in the heating main mode, selectively switch the operation mode of the outdoor unit to the cooling main mode according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio;

S203: If the outdoor ambient temperature is greater than or equal to the second preset temperature, and the cooling ratio is greater than the fourth preset ratio, switch the operation mode of the outdoor unit to the cooling main mode;

S204: If the outdoor ambient temperature is less than the second preset temperature and greater than or equal to the third preset temperature, and the cooling ratio is greater than the fifth preset ratio, switch the operation mode of the outdoor unit to the cooling main mode;

S205: If the outdoor ambient temperature is less than the third preset temperature and greater than or equal to the fourth preset temperature, and the cooling ratio is greater than the sixth preset ratio, switch the operation mode of the outdoor unit to the cooling main mode.

It should be noted that the present invention does not impose any restrictions on the specific value of the fourth preset temperature, and technicians can set it by themselves according to actual use requirements, as long as the fourth preset temperature is lower than the third preset temperature That's it. In addition, the present invention does not impose any restrictions on the specific values of the fourth preset ratio, the fifth preset ratio, and the sixth preset ratio, and technicians can set them by themselves according to actual use requirements, as long as the three It only needs to satisfy the relationship that the fourth preset ratio is smaller than the fifth preset ratio and smaller than the sixth preset ratio.

In addition, when the outdoor unit is operating in the heating main mode, if the judgment result of the controller does not meet the above three conditions, the outdoor unit can continue to maintain the heating main mode without switching.

As a specific example, if the operating mode of the outdoor unit is to be switched from the main mode of heating shown in Figure 2 to the main mode of cooling, the actions of each valve and the mode of each indoor unit are as follows:

External machine mode	Heating body	Refrigeration body
4WV1	ON	OFF
4WV2	ON	OFF
4WV3	ON	ON
upper heat exchanger	Heating	Refrigeration
lower heat exchanger	Heating	Refrigeration
LEVA1	superheat control	fully open
LEVA2	superheat control	fully open

Internal machine, valve box mode	Inner unit, valve box	Inner unit, valve box
Indoor unit 13HP	Heating	Refrigeration
Indoor unit 21HP	Refrigeration	Heating
Indoor unit 31HP	Refrigeration	Heating
Indoor unit 43HP	Heating	Refrigeration

In addition, the control method of the present invention further includes: when the number of indoor units operating in the cooling mode is equal to the number of indoor units operating in the heating mode, if the sum of the number of indoor units operating in the cooling mode is equal to the number of indoor units operating in the heating mode If the sum of the horsepower of the indoor units is also equal, the heat exchanger of the outdoor unit is turned off, and the outdoor unit is operated in a heat recovery mode.

As a specific example, as shown in Figure 3, the indoor unit 1 and the indoor unit 2 in Figure 3 are operating in the cooling mode, and the indoor units 3 and 4 are operating in the heating mode, that is, the indoor units operating in the cooling mode The number of indoor units running in the heating mode is equal to the number of indoor units running in the cooling mode, and the sum of the number of indoor units running in the cooling mode is also equal to the sum of the number of indoor units running in the heating mode. At this time, the operating mode of the outdoor unit is heat recovery In this mode, the heat exchangers of the two outdoor units are turned off, so that the refrigerant only passes through the four indoor heat exchangers for heat exchange, and the refrigerant flows as shown in Figure 3. In this mode, the actions of each valve and each interior The machine mode is as follows:

Based on the setting of the heat recovery mode, the three-pipe multi-connected air conditioner unit of the present invention can completely close all outdoor heat exchangers, so that the refrigerant absorbs heat in the room that needs to be cooled, and then releases the heat to the room that needs to be heated. In this way, heat recovery can be effectively realized, and waste of heat load can be effectively avoided.

In addition, it should be noted that although this preferred embodiment closes all outdoor heat exchangers to achieve complete recovery of heat, this control method is obviously not restrictive, and technicians can also close only part of the outdoor heat exchangers according to actual needs. Heat exchanger, so as to realize partial recovery of heat, this control method should also belong to the protection scope of the present invention.

So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings, but those skilled in the art will easily understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims (10)

1. A control method for a three-pipe multi-connected air conditioner unit, characterized in that the control method includes:

   Obtaining the outdoor ambient temperature, the cooling ratio of the three-pipe multi-connected air conditioner unit and the current operating mode of the outdoor unit;

   The operation mode of the outdoor unit is selectively switched according to the outdoor ambient temperature, the cooling ratio and the current operation mode.
2. The control method according to claim 1, wherein the step of "selectively switching the operation mode of the outdoor unit according to the outdoor ambient temperature, the cooling ratio and the current operation mode" comprises:

   When the outdoor unit is operating in the cooling main mode, selectively switch the operation mode of the outdoor unit to cooling according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio. Hot subject mode.
3. The control method according to claim 2, characterized in that, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit The steps for heating the main mode" include:

   If the outdoor ambient temperature is less than or equal to the first preset temperature and greater than or equal to the second preset temperature, and the cooling ratio is less than or equal to the first preset ratio, switch the operation mode of the outdoor unit to Heating main mode.
4. The control method according to claim 3, characterized in that, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit The steps of "Main heating mode" also include:

   If the outdoor ambient temperature is less than the second preset temperature and greater than or equal to a third preset temperature, and the cooling ratio is less than or equal to the second preset ratio, switch the operation mode of the outdoor unit to Heating main mode;

   Wherein, the second preset ratio is greater than the first preset ratio.
5. The control method according to claim 4, characterized in that, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit The steps of "Main heating mode" also include:

   If the outdoor ambient temperature is less than the third preset temperature and the cooling ratio is less than or equal to the third preset ratio, switch the operation mode of the outdoor unit to the heating main mode;

   Wherein, the third preset ratio is greater than the second preset ratio.
6. The control method according to claim 5, wherein the step of "selectively switching the operation mode of the outdoor unit according to the outdoor ambient temperature, the cooling ratio and the current operation mode" further includes :

   When the outdoor unit is operating in the heating main mode, according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operating mode of the outdoor unit to Cooling main mode.
7. The control method according to claim 6, characterized in that, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit For Cooling Master Mode" steps include:

   If the outdoor ambient temperature is greater than or equal to the second preset temperature, and the cooling ratio is greater than a fourth preset ratio, the operation mode of the outdoor unit is switched to a cooling main mode.
8. The control method according to claim 7, characterized in that, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit For Cooling Main Mode" steps also include:

   If the outdoor ambient temperature is less than the second preset temperature and greater than or equal to the third preset temperature, and the cooling ratio is greater than a fifth preset ratio, switch the operation mode of the outdoor unit to Cooling main mode;

   Wherein, the fifth preset ratio is greater than the fourth preset ratio.
9. The control method according to claim 8, characterized in that, "according to the numerical range of the outdoor ambient temperature and the numerical range of the cooling ratio, selectively switch the operation mode of the outdoor unit For Cooling Main Mode" steps also include:

   If the outdoor ambient temperature is less than the third preset temperature and greater than or equal to the fourth preset temperature, and the cooling ratio is greater than the sixth preset ratio, switch the operation mode of the outdoor unit to cooling main model;

   Wherein, the sixth preset ratio is greater than the fifth preset ratio.
10. The control method according to any one of claims 1 to 9, wherein the control method further comprises:

    When the number of indoor units operating in cooling mode is equal to the number of indoor units operating in heating mode, if the sum of the number of indoor units operating in cooling mode is also equal to the sum of the number of indoor units operating in heating mode, The heat exchanger of the outdoor unit is then turned off, so that the outdoor unit operates in a heat recovery mode.

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