WO2023279608A1

WO2023279608A1 - Control method for oil recovery in pipe of outdoor unit

Info

Publication number: WO2023279608A1
Application number: PCT/CN2021/129797
Authority: WO
Inventors: 罗荣邦
Original assignee: 青岛海尔空调器有限总公司; 青岛海尔空调电子有限公司; 海尔智家股份有限公司
Priority date: 2021-07-09
Filing date: 2021-11-10
Publication date: 2023-01-12
Also published as: CN113483475A; CN113483475B

Abstract

The present invention relates to the technical field of air conditioner self-cleaning, and relates in particular to a control method for oil recovery in a pipe of an outdoor unit. The present application aims to solve the problem of how to implement oil recovery in a pipe of an outdoor unit. For said purpose, the air conditioner of the present application comprises a recovery pipe, one end of the recovery pipe communicating with an inlet of an outdoor heat exchanger, the other end communicating with an air suction port of a compressor, and an on-off valve being provided on the recovery pipe. The method comprises: in response to a received instruction for recovering oil in a pipe, entering an outdoor unit in-pipe oil recovery mode; controlling an air conditioner to operate in a heating mode; controlling a compressor to adjust to a preset first recovery frequency; adjusting the degree of opening of a throttling device, so that the coil temperature of the outdoor heat exchanger is below or equal to a preset temperature; when the coil temperature is below or equal to the preset temperature and continues for a first preset duration, controlling the air conditioner to switch to a cooling mode; and controlling the on-off valve to open, and turning off the throttling device to the smallest degree of opening. In the present application, oil recovery in a pipe of an outdoor unit can be achieved.

Description

Control method of oil pollution recovery in pipe of outdoor unit

technical field

The invention relates to the technical field of self-cleaning of air conditioners, in particular to a method for controlling the recovery and control of oil pollution in pipes of outdoor machines.

Background technique

For the outdoor unit of the air conditioner, the refrigerating machine oil will participate in the cycle along with the refrigerant during use. During the cycle, the refrigerating machine oil will have carbon and impurities, and these oils will flow to the hairpin tube of the outdoor heat exchanger along with the refrigerant. The hairpin tube is an internally threaded copper tube, which affects the flow of refrigeration oil. Coupled with the centrifugal force of the refrigerant flow, the oil and oil cannot return to the inside of the compressor in time, and stay on the inner wall of the threaded copper tube, hindering the connection between the refrigerant and the coil. The heat transfer between them reduces the heat transfer temperature difference and makes the heating effect of the air conditioner worse.

Correspondingly, there is a need in the art for a new control method for oil pollution recovery in pipes of outdoor machines to solve the above problems.

Contents of the invention

In order to solve at least one of the above-mentioned problems in the prior art, that is, to solve the problem of how to realize the oil pollution recovery in the pipe of the outdoor unit, the application provides a control method for oil pollution recovery in the pipe of the outdoor machine, which is applied to an air conditioner, and the air conditioner It includes a compressor connected through a refrigerant pipeline, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchanger. The air conditioner also includes a recovery pipeline, and one end of the recovery pipeline is connected to the outdoor heat exchanger. The inlet of the heater is connected, and the other end of the recovery pipeline is connected with the suction port of the compressor. An on-off valve is arranged on the recovery pipeline, and the on-off valve is a normally closed valve.

The control methods include:

Responding to the received instruction to recover the oil pollution in the pipe of the outdoor unit, enter the oil pollution recovery mode in the pipe of the outdoor machine;

controlling the air conditioner to operate in a heating mode;

controlling the compressor to adjust to a preset first recovery frequency;

adjusting the opening of the throttling device so that the coil temperature of the outdoor heat exchanger is less than or equal to a preset temperature;

When the coil temperature is less than or equal to the preset temperature and lasts for a first preset time, control the air conditioner to switch to cooling mode;

Controlling the on-off valve to open and the throttling device to close to a minimum opening;

Wherein, the preset temperature is greater than the freezing temperature of the refrigerating machine oil.

In the preferred technical solution of the control method for oil pollution recovery in pipes of the outdoor unit, after the step of "controlling the air conditioner to switch to cooling mode", the control method further includes:

Controlling the compressor to adjust to a preset second recovery frequency.

In the preferred technical solution of the above-mentioned control method for oil pollution recovery in pipes of outdoor units, the second recovery frequency is the highest limit frequency corresponding to the outdoor ambient temperature.

In the preferred technical solution of the control method for oil pollution recovery in the pipe of the outdoor unit, before the step of "adjusting the opening degree of the throttling device", the control method further includes:

Control the outdoor fan to run at the lowest speed.

Control the indoor fan to run at the set speed.

The fan in the control room stops running.

In the preferred technical solution of the control method for oil pollution recovery in pipes of the above-mentioned outdoor unit, the control method further includes:

When entering the oil pollution recovery mode in the pipe of the outdoor unit, the outdoor anti-freezing protection function and the outdoor ambient temperature frequency limiting function are turned off.

In the preferred technical solution of the control method for oil pollution recovery in pipes of the outdoor unit, after the step of "controlling the on-off valve to open and the throttle device to close to the minimum opening degree", the control method further includes:

After the on-off valve is opened and the throttling device is closed to the minimum opening for a second preset period of time, the oil pollution recovery mode in the pipe of the outdoor unit is exited.

In the preferred technical solution of the above-mentioned control method for oil pollution recovery in the pipe of the outdoor unit, the step of "exiting the oil pollution recovery mode in the pipe of the outdoor machine" further includes:

Controlling the air conditioner to return to the operating mode before entering the oil pollution recovery mode in the outdoor unit pipe;

controlling the compressor to return to the frequency before entering the oil pollution recovery mode in the pipe of the outdoor unit;

controlling the throttling device to return to the opening before entering the oil pollution recovery mode in the pipe of the outdoor unit;

Control the on-off valve to close.

In the preferred technical solution of the control method for oil pollution recovery in the pipe of the outdoor unit, the step of "exiting the oil pollution recovery mode in the pipe of the outdoor machine" further includes:

Controlling the indoor fan to keep off;

When the coil temperature of the indoor heat exchanger reaches the anti-cold wind temperature, the indoor fan is controlled to start running.

It should be noted that, in the preferred technical solution of this application, the air conditioner includes a compressor connected through a refrigerant pipeline, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchanger, and the air conditioner also includes a recovery pipe One end of the recovery pipeline is connected to the inlet of the outdoor heat exchanger, and the other end of the recovery pipeline is connected to the suction port of the compressor. An on-off valve is installed on the recovery pipeline, and the on-off valve is a normally closed valve. The method includes : Responding to the received instruction to recover the oil pollution in the pipe of the outdoor unit, enter the oil pollution recovery mode in the pipe of the outdoor unit; control the air conditioner to run in the heating mode; control the compressor to adjust to the preset first recovery frequency; adjust the throttling device Opening degree, so that the coil temperature of the outdoor heat exchanger is less than or equal to the preset temperature; when the coil temperature is less than or equal to the preset temperature and lasts for the first preset time, control the air conditioner to switch to cooling mode; control the on-off valve to open , The throttling device is closed to the minimum opening; wherein, the preset temperature is greater than the freezing temperature of the refrigerating machine oil.

Through the above-mentioned control method, the method of the present application can realize the recovery of the oil in the pipe of the outdoor unit, and solve the problem of dirty blockage in the pipe of the outdoor heat exchanger. Specifically, by controlling the air conditioner to run in the heating mode first, and adjusting the opening of the throttling device so that the coil temperature of the outdoor heat exchanger is less than or equal to the preset temperature, due to the high viscosity of the refrigerator oil and oil, the freezing point is higher than that of the refrigerant. The freezing point of refrigerating machine oil is higher than that of oil, so the oil in refrigerating machine oil first solidifies and peels off from the refrigerant cycle when the refrigerant temperature drops, and adheres to the inner wall of the coil of the outdoor heat exchanger, while the normal Refrigerator oil is circulated back to the compressor along with the refrigerant, so that the oil in the refrigerant is separated and temporarily stored inside the coil of the outdoor heat exchanger. When the coil temperature is less than or equal to the preset temperature and lasts for the first preset time, the heat exchanger of the air conditioner is controlled to switch to cooling mode, and the on-off valve is opened, and the throttling device is closed to the minimum opening degree, so that the rapid cooling of the high-temperature and high-pressure refrigerant can be used. The flow impacts the inside of the coil of the outdoor heat exchanger, and the oil temporarily stored inside the coil is melted by high temperature and returns directly to the inside of the compressor along with the refrigerant through the recovery pipeline to realize the oil recovery of the outdoor heat exchanger. In addition, by setting up the recovery pipeline, it is possible to directly bring the oil back to the compressor for recovery during the oil recovery process, reduce the flow stroke of the high-temperature refrigerant, reduce the pressure drop of the refrigerant, improve the oil recovery effect, save the oil recovery time, and ensure user experience.

Description of drawings

The method for controlling the recovery of oil pollution in the pipe of the outdoor unit of the present application will be described below with reference to the accompanying drawings. In the attached picture:

Fig. 1 is the system diagram of the air conditioner of the present application in heating mode;

Fig. 2 is the system diagram of the air conditioner of the present application in cooling mode;

Fig. 3 is the flow chart of the oil pollution recovery control method in the pipe of the outdoor unit of the present application;

Fig. 4 is a logic diagram of a possible implementation process of the method for controlling oil pollution recovery in pipes of outdoor units of the present application.

List of reference signs

1. Compressor; 2. Four-way valve; 3. Outdoor heat exchanger; 4. Throttle device; 5. Indoor heat exchanger; 6. Refrigerant pipeline; 7. Recovery pipeline; 8. On-off valve; 9 , Liquid reservoir, 10, temperature sensor.

detailed description

Preferred embodiments of the present application 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 principles of the present application, and are not intended to limit the protection scope of the present application. For example, although the detailed steps of the method of the present application are described in detail below, those skilled in the art can combine, split and change the order of the above steps without departing from the basic principles of the present application. The scheme does not change the basic idea of the application, and therefore also falls within the scope of protection of the application.

It should be noted that, in the description of the present application, the terms "first", "second", and "third" are used for description purposes only, and should not be understood as indicating or implying relative importance.

It should also be noted that, in the description of this application, unless otherwise specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those skilled in the art can understand the specific meanings of the above terms in this application according to specific situations.

Referring first to FIG. 1 , the structure of the air conditioner of the present application will be described. Wherein, FIG. 1 is a system diagram of the air conditioner of the present application in a heating mode.

As shown in FIG. 1 , in a possible implementation, the air conditioner includes a compressor 1 , a four-way valve 2 , an outdoor heat exchanger 3 , a throttling device 4 , an indoor heat exchanger 5 and a liquid accumulator 9 . The exhaust port of the compressor 1 is connected with the P port of the four-way valve 2 through the refrigerant pipeline 6, and the E port of the four-way valve 2 is connected with the inlet of the indoor heat exchanger 5 through the refrigerant pipeline 6. The outlet communicates with one port of the throttling device 4 through the refrigerant pipeline 6, and the other port of the throttling device 4 communicates with the inlet of the outdoor heat exchanger 3 through the refrigerant pipeline 6, and the outlet of the outdoor heat exchanger 3 passes through the refrigerant pipeline 6 is connected with the C port of the four-way valve 2, the S port of the four-way valve 2 is connected with the inlet of the accumulator 9 through the refrigerant pipeline 6, and the outlet of the accumulator 9 is connected with the suction port of the compressor 1 through the pipeline . The throttling device 4 is preferably an electronic expansion valve, and a filter is provided in the liquid storage 9, and the liquid storage 9 can store refrigerant, separate gas and liquid of refrigerant, filter oil, eliminate noise, and buffer refrigerant.

The air conditioner also includes a recovery pipeline 7 and an on-off valve 8. The recovery pipeline 7 adopts a copper tube with a smooth inner wall. On the pipeline 6 , the second end of the copper tube is arranged on the refrigerant pipeline 6 between the S interface of the four-way valve 2 and the inlet of the liquid storage tank 9 . The on-off valve 8 is preferably a solenoid valve. The solenoid valve is a normally closed valve and is arranged on the recovery pipeline 7. The solenoid valve communicates with the controller of the air conditioner to receive the opening and closing signals issued by the controller. Of course, the on-off valve 8 can also be an electronically controlled valve such as an electronic expansion valve.

In order to realize the following method, the coil of the outdoor heat exchanger 3 of the present application is further provided with a temperature sensor 10 , and the temperature sensor 10 is used to detect the temperature of the coil of the outdoor heat exchanger 3 . The principle of detecting the coil temperature of the heat exchanger by the temperature sensor 10 is common knowledge in the art, and will not be repeated here.

The method for recovering oil in pipes of outdoor units in this embodiment will be described below in conjunction with the structure of the air conditioner above, but those skilled in the art can understand that the specific structural composition of the air conditioner is not static and can be adjusted by those skilled in the art , for example, components can be added or deleted on the basis of the above-mentioned structure of the air conditioner.

The method for recovering the oil in the pipe of the outdoor unit of the present application will be introduced below with reference to FIG. 1 , FIG. 2 and FIG. 3 . Wherein, FIG. 2 is a system diagram of the air conditioner of the present application in cooling mode; FIG. 3 is a flow chart of the method for recovering oil in pipes of the outdoor unit of the present application.

As shown in Figure 3, in order to solve the problem of how to realize the oil pollution recovery in the pipe of the outdoor machine, the oil pollution recovery method in the pipe of the outdoor machine of the present application includes:

S101. In response to receiving an instruction to recover the oil in the pipe of the outdoor unit, enter the oil pollution recovery mode in the pipe of the outdoor unit.

In a possible implementation, the user can initiate an instruction to recover the oil pollution in the pipe of the outdoor unit, such as sending an instruction to the air conditioner through a button on the remote control, or sending an instruction through a terminal connected to the air conditioner through communication, wherein the terminal It can be the APP installed on the smart device, and the APP can send instructions to the air conditioner directly or through the cloud. Among them, smart devices include but are not limited to mobile phones, tablet computers, smart speakers, smart watches, etc., and the ways of communication and connection between smart devices and air conditioners or the cloud include but not limited to wifi, bluetooth, infrared, 3G/4G/5G, etc. After the air conditioner receives the command to recover the oil in the pipe of the outdoor unit, it switches the operation mode to the oil recovery mode in the pipe of the outdoor unit, and starts to recover the oil in the pipe of the outdoor unit. Wherein, the oil pollution recovery mode in the pipe of the outdoor unit can be a computer program, which is pre-stored in the air conditioner. When operating this mode, the air conditioner controls the operation of each component of the air conditioner according to the steps set by the program.

Of course, the oil pollution recovery command in the pipe of the outdoor unit can also be automatically issued when the air conditioner meets certain entry conditions. For example, it can be 20h-40h.

S103. Control the air conditioner to run in the heating mode.

In a possible implementation, the switching between the operating modes of the air conditioner is controlled by controlling the power on and off of the four-way valve. For example, when the four-way valve is powered off, the air conditioner operates in the heating mode, When powered on, the air conditioner operates in cooling mode. In this embodiment, after entering the oil pollution recovery mode in the outdoor unit pipe, if the air conditioner is running in the heating mode, no adjustment is required, and the air conditioner is controlled to continue running; if the air conditioner is running in the non-heating mode, the air conditioner is controlled to switch to Heating mode operation.

S105. Control the compressor to adjust to the preset first recovery frequency.

In a possible implementation manner, the first recovery frequency is a frequency determined in advance through experiments, for example, it may be determined based on the correspondence between the outdoor ambient temperature and the first recovery frequency in Table 1 below. When the compressor operates at the first recovery frequency, it facilitates the implementation of the subsequent control process.

Table 1 Comparison table between outdoor ambient temperature and first recycling frequency

室外环境温度(℃)Outdoor ambient temperature (℃)	第一回收频率(Hz)First recovery frequency (Hz)
Tao≤-20Tao≤-20	外环温限频最高频-5Maximum frequency of outer ring temperature limit frequency -5
-20<Tao≤-10-20<Tao≤-10	外环温限频最高频-5Maximum frequency of outer ring temperature limit frequency -5
-10<Tao≤-5-10<Tao≤-5	外环温限频最高频-5Maximum frequency of outer ring temperature limit frequency -5
-5<Tao≤0-5<Tao≤0	外环温限频最高频Maximum frequency of outer ring temperature limit frequency
0<Tao≤50<Tao≤5	外环温限频最高频Maximum frequency of outer ring temperature limit frequency
5<Tao≤105<Tao≤10	外环温限频最高频+5The highest frequency of the outer ring temperature limit frequency +5
10<Tao≤1610<Tao≤16	外环温限频最高频+5The highest frequency of the outer ring temperature limit frequency +5
Tao>16Tao>16	外环温限频最高频+5The highest frequency of the outer ring temperature limit frequency +5

It should be noted that although this application does not list specific values to illustrate the first recovery frequency, this does not mean that the method of this application cannot be implemented. Under different types of air conditioners and different environmental conditions, the first recovery frequency may There are differences, so those skilled in the art can set the first recovery frequency based on specific application scenarios, as long as the setting of the frequency can facilitate the implementation of the subsequent control process.

S107. Control the opening degree of the throttling device, so that the coil temperature of the outdoor heat exchanger is less than or equal to the preset temperature.

In a possible implementation, the temperature sensor detects the coil temperature of the outdoor heat exchanger, and dynamically adjusts the opening of the electronic expansion valve, so that the coil temperature of the outdoor heat exchanger is less than or equal to a preset temperature. Preferably, the preset temperature is higher than the freezing temperature of the refrigerator oil, so, since the freezing points of the refrigerator oil and the refrigerant are far lower than the freezing point of the oil, the preset temperature is set to be higher than the freezing temperature of the refrigerator oil, and the coil temperature can be lower than When the temperature is equal to the preset temperature, the oil will be solidified and precipitated first, while the refrigeration oil and refrigerant will circulate normally. Different types of refrigerating machine oil have different freezing points, so the specific value of the preset temperature is determined based on the type of refrigerating machine oil used. For example, in order to ensure fluidity, the freezing point of refrigerating machine oil is below -50 degrees. The preset temperature can be set from -10°C to -25°C, and in this application, the preset temperature can be -15°C. That is to say, the coil temperature of the outdoor heat exchanger is less than or equal to the preset temperature as the control purpose, and the coil temperature of the outdoor heat exchanger is always less than or equal to Preset temperature status.

Referring to Figure 1, when the air conditioner is running in the heating mode, the coil temperature of the outdoor heat exchanger is kept at a state of less than or equal to -15°C. At this time, the oil in the refrigerating machine oil flowing through the outdoor heat exchanger is circulated from the refrigerant. It is peeled off and attached to the inner wall of the coil of the outdoor heat exchanger.

Certainly, in other implementation manners, the coil temperature of the outdoor heat exchanger can also be lower than or equal to the preset temperature by adjusting the opening degree of the electronic expansion valve to a fixed opening degree.

S109. When the coil temperature is less than or equal to the preset temperature for a first preset time period, control the air conditioner to switch to the cooling mode.

In a possible implementation manner, the first preset duration may be any value in 5-15 minutes. Preferably, the first preset time length in this embodiment is 10 minutes. When the coil temperature is less than or equal to -15°C and lasts for 10 minutes, the oil in the outdoor heat exchanger has been stripped, and the stripped oil can be recovered at this time operate. At this time, the switch between the operation modes of the air conditioner is controlled by controlling the power on and off of the four-way valve, for example, the power off of the four-way valve is controlled, and the air conditioner operates in the cooling mode.

S111. Control the on-off valve to open, and the throttling device to close to a minimum opening.

In a possible implementation manner, after the operation mode is switched to the refrigeration mode, the on-off valve is controlled to be opened, and the throttling device is closed to a minimum opening. Control the throttling device to close to the minimum opening degree, that is, the state where the opening degree is 0, the throttling device realizes complete throttling, and the refrigerant cannot flow through. At this time, as shown by the arrow in Figure 2, the high-temperature and high-pressure refrigerant discharged from the compressor flows through the outdoor heat exchanger, and the high-temperature and high-pressure refrigerant quickly impacts the coil of the outdoor heat exchanger, and the oil that is temporarily stored inside the coil is melted. The high-temperature refrigerant directly flows back to the accumulator through the recovery pipeline, and is intercepted and filtered by the filter inside the accumulator to achieve the purpose of oil recovery.

It can be seen that by controlling the air conditioner to run in the heating mode first, and adjusting the opening of the throttling device so that the coil temperature of the outdoor heat exchanger is less than or equal to the preset temperature, due to the high viscosity of the refrigeration oil and oil, the freezing point is higher than The refrigerant is high, and the freezing point of the refrigerator oil is higher than that of the oil. Therefore, the oil in the refrigerator oil is first solidified and peeled off from the refrigerant cycle during the temperature drop of the refrigerant, and adheres to the inner wall of the coil of the outdoor heat exchanger. The high-quality refrigeration oil is circulated back to the compressor along with the refrigerant, so that the oil in the refrigerant is separated and temporarily stored inside the coil of the outdoor heat exchanger. When the coil temperature is less than or equal to the preset temperature and lasts for the first preset time, control the heat exchanger of the air conditioner to switch to cooling mode, open the on-off valve, and close the throttling device, so that the rapid flow of high-temperature and high-pressure refrigerant can be used to impact the outdoor exchange. Inside the coil of the heater, the oil stain temporarily stored inside the coil is melted by high temperature and returns directly to the liquid receiver along with the refrigerant through the recovery pipeline to realize the oil recovery of the outdoor heat exchanger.

In addition, by setting the recovery pipeline in the air conditioner, the application can use the recovery pipeline to realize the recovery of oil pollution in the process of recovering the oil pollution in the pipe of the outdoor heat exchanger, so as to realize the flushing of the outdoor heat exchanger by the high-temperature and high-pressure refrigerant. Afterwards, it does not need to go through the indoor heat exchanger again, but directly brings the oil back to the liquid receiver for recovery and filtration, and then it is compressed and discharged by the compressor again, which reduces the flow stroke of high-temperature refrigerant, reduces the pressure drop along the way, and improves the internal pressure of the pipe. Oil recovery effect.

In a possible implementation manner, after the step of "controlling the air conditioner to switch to cooling mode", the method further includes: controlling the compressor to adjust to a preset second recovery frequency. Wherein, the second recovery frequency is preferably the highest limit frequency corresponding to the outdoor ambient temperature. Usually, the operating frequency of the compressor is affected by the outdoor ambient temperature and cannot be increased indefinitely, otherwise the phenomenon of high temperature protection shutdown of the compressor will easily occur, which will have a negative impact on the life of the compressor. Therefore, the compressors are all equipped with a protection mechanism. Under different outdoor ambient temperatures, the highest limit frequency is correspondingly set. The second recovery frequency of this application is the highest limit frequency of the compressor at the current outdoor ambient temperature. Under the frequency limit, the compressor can increase the temperature and pressure of the refrigerant in the shortest time, thereby improving the oil recovery effect. Wherein, the manner of obtaining the outdoor ambient temperature is a conventional means in the field, and will not be repeated here.

In a possible implementation manner, before the step of "adjusting the opening degree of the throttling device", the method further includes: controlling the indoor fan to run at a set speed. Specifically, before adjusting the opening degree of the throttling device, by controlling the indoor fan to run at a set speed, the heat exchange effect between the refrigerant in the indoor heat exchanger and the environment can be improved, thereby reducing the temperature and pressure of the refrigerant and increasing the temperature of the refrigerant. The evaporative effect in the outdoor heat exchanger causes the outdoor coil to cool down to the preset temperature more quickly. Among them, the set speed can be 600r/min-800r/min, and the speed should not be too high, because the indoor unit is in a heating state, if the speed is too high, it will easily cause a sudden change in the indoor environment temperature, which will bring a bad experience to the user.

In a possible implementation manner, before the step of "adjusting the opening degree of the throttling device", the method further includes: controlling the outdoor fan to run at a minimum speed. Specifically, before adjusting the opening degree of the throttling device, the outdoor fan is firstly controlled to run at the lowest speed, so as to reduce the heat exchange effect between the outdoor heat exchanger and the air, thereby speeding up the temperature reduction speed of the outdoor coil, Improve oil recovery efficiency.

In a possible implementation manner, the method further includes: after controlling the air conditioner to switch to cooling mode, controlling the indoor fan to run for a third preset time period and then stop running. Specifically, the third preset duration may be any value in 10s-1min, and in this application may be 30s. When running in the cooling mode, there is no refrigerant flowing through the indoor heat exchanger, so the temperature of the air outlet from the indoor unit gradually decreases, which will bring a bad experience to the user. At this time, the fan in the control room stops running after running for 30 seconds, which can prevent the temperature of the outlet air from being too low and affect the user experience.

In a possible implementation manner, the method further includes: when entering the oil pollution recovery mode in the pipe of the outdoor unit, turning off the outdoor anti-freezing protection function and the outdoor ambient temperature frequency limiting function. Since the coil temperature of the outdoor heat exchanger needs to be lowered to a lower value, in order to reach this condition as soon as possible, the compressor needs to run at high frequency. function to ensure the smooth execution of this method. But other protection functions are turned on as usual, such as compressor exhaust protection and current overload protection, and other functions remain turned on to prevent adverse effects on the life of the air conditioner.

Of course, the specific control process of the oil pollution recovery mode in the outdoor unit pipe is not the only one. To ensure that the heating mode is operated first to make the coil temperature less than or equal to the preset temperature, and then switch to the cooling mode, open the on-off valve, and close the throttling device. Those skilled in the art can adjust the control method. For example, on the premise that the coil temperature of the outdoor heat exchanger can be kept at or below the preset temperature, the operation frequency of the compressor, the opening degree of the electronic expansion valve, the speed of the indoor fan and the outdoor fan can be controlled in the above control mode. One or more of the rotational speeds are omitted.

In a possible implementation manner, the method further includes: after the on-off valve is opened and the throttling device is closed to the minimum opening for a second preset period of time, exiting the oil pollution recovery mode in the pipe of the outdoor unit. Wherein, the second preset time length can be any value in 3min-10min, preferably 5min in this application. When the throttling device and the on-off valve are opened for 5 minutes, the high-temperature and high-pressure refrigerant has circulated many times, which is enough to produce a better oil recovery effect in the pipe. Therefore, when the throttling device and the on-off valve are opened for 5 minutes, it will exit the pipe of the outdoor unit Oil recovery mode.

Specifically, the step of exiting the oil pollution recovery mode in the outdoor unit pipe further includes: controlling the air conditioner to return to the operating mode before entering the oil pollution recovery mode in the outdoor machine pipe, controlling the compressor to return to the frequency before entering the oil pollution recovery mode in the outdoor machine pipe, controlling the indoor Keep the fan off, control the throttling device to return to the opening before entering the oil pollution recovery mode in the outdoor unit pipe, and control the on-off valve to close. After the oil pollution recovery process in the pipe is completed, the air conditioner needs to return to the operating mode before the oil pollution recovery in the pipe to continue to adjust the indoor temperature. Take the air conditioner running in the heating mode before entering the oil pollution recovery mode in the outdoor unit pipe as an example. After the oil pollution recovery mode in the outdoor unit pipe is executed, it needs to switch back to the heating mode. At this time, control the four-way valve to restore the heating mode, control the compressor to return from the second recovery frequency to the frequency before entering the oil pollution recovery mode in the outdoor unit pipe, control the indoor fan to keep off, and control the electronic expansion valve to return to the outdoor unit pipe. The opening before the oil recovery mode controls the closing of the on-off valve so that the refrigerant flows in the normal heating mode. Wherein, the indoor fan is kept turned off, so as to prevent the user from having a bad user experience due to the temperature of the indoor heat exchanger coil being too low when the air conditioner just switches to the heating mode.

Correspondingly, after the indoor fan is controlled to be turned off, the coil temperature of the indoor heat exchanger is obtained. When the coil temperature of the indoor heat exchanger reaches the anti-cold wind temperature, the indoor fan is controlled to start running. Among them, when the coil temperature of the indoor heat exchanger reaches the anti-cold air temperature, the indoor fan can no longer blow cold air outside, so the indoor fan can be controlled to start and run to meet the heating demand of the user. So far, the air conditioner has completely recovered the heating parameters before entering the outdoor unit pipe for oil recovery and continues to operate.

Of course, the way of exiting the oil pollution recovery mode in the outdoor unit pipe is not limited to the above one, and those skilled in the art can freely choose specific control methods on the premise that the air conditioner can be restored to the operating state before entering the oil pollution recovery mode in the outdoor unit pipe way, this choice does not depart from the principles of the present application. For example, the outdoor fan can be controlled to return to the operating state before entering the oil pollution recovery mode in the outdoor unit pipe; for another example, the indoor fan can be controlled to start running at the same time the air deflector is controlled to blow upward, and then the air deflector can be controlled to blow upward after a certain period of time. down air.

A possible implementation process of the present application will be described below with reference to FIG. 4 . Wherein, FIG. 4 is a logic diagram of a possible implementation process of the method for recovering oil pollution in pipes of outdoor units of the present application.

As shown in Figure 4, in a possible implementation process, when the air conditioner is running in the heating mode, the user sends an instruction to the air conditioner to recover the oil in the pipe of the outdoor unit through the remote control button:

First execute step S201, the air conditioner enters the oil pollution recovery mode in the outdoor unit pipe, that is, control the air conditioner to maintain the heating mode operation, control the compressor to adjust to the first recovery frequency, control the indoor fan to run at the set speed of 700r/min, and control the outdoor fan Run at lowest RPM.

Next, step S203 is executed to adjust the opening degree of the throttling device and obtain the coil temperature Tc of the outdoor heat exchanger.

Next, step S205 is executed to determine whether the coil temperature Tc≤-15°C of the outdoor heat exchanger and the duration t1≥10min are simultaneously established. If both conditions are established, execute step S207. Otherwise, when the two conditions are not simultaneously established, return Execute step S203.

S207, control the air conditioner to operate in the cooling mode, control the compressor to adjust to the highest frequency limit corresponding to the outdoor ambient temperature, control the indoor fan to run for 30 seconds and then turn off, control the solenoid valve to open, and the electronic expansion valve to close to the minimum opening.

Next, step S209 is executed to judge whether the duration t2≥5min of the state where the solenoid valve is open and the electronic expansion valve is closed to the minimum opening is established; if the judgment result is true, then step S211 is executed; otherwise, when the judgment result is not true, return Continue to execute step S209.

S211, exit the oil pollution recovery mode in the pipe, specifically, control the air conditioner to operate in the heating mode, control the electronic expansion valve to return to the opening degree before the oil pollution recovery mode in the outdoor machine pipe, control the indoor fan to remain closed, and control the compressor to return to the outdoor unit The frequency before the oil pollution recovery mode in the pipe, and the control solenoid valve is closed.

Next, step S213 is executed to judge whether the coil temperature Tp of the indoor heat exchanger is greater than or equal to 40°C; if the judgment result is true, execute step S215; otherwise, return to step S213;

S215, controlling the indoor fan to start running. At this point, the air conditioner returns to the heating mode operation before entering the oil pollution recovery mode in the outdoor unit pipe.

Those skilled in the art can understand that the above air conditioner also includes some other known structures, such as a processor, a controller, a memory, etc., wherein the memory includes but not limited to random access memory, flash memory, read-only memory, programmable read-only memory, Volatile memory, non-volatile memory, serial memory, parallel memory or registers, etc., processors include but not limited to CPLD/FPGA, DSP, ARM processors, MIPS processors, etc. These well-known structures are not shown in the figures in order to unnecessarily obscure the embodiments of the present disclosure.

In the above embodiment, although the various steps are described according to the above sequence, those skilled in the art can understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in this order, and they can be performed at the same time ( Parallel) execution or execution in reversed order, these simple changes are all within the protection scope of the present application.

So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Under the premise of not departing from the principle of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present application.

Claims

A method for recovering oil pollution in pipes of an outdoor unit, applied to an air conditioner, characterized in that the air conditioner includes a compressor connected through a refrigerant pipeline, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchange The air conditioner also includes a recovery pipeline, one end of the recovery pipeline communicates with the inlet of the outdoor heat exchanger, and the other end of the recovery pipeline communicates with the suction port of the compressor, so An on-off valve is arranged on the recovery pipeline, and the on-off valve is a normally closed valve.

The control methods include:

Responding to the received instruction to recover the oil pollution in the pipe of the outdoor unit, enter the oil pollution recovery mode in the pipe of the outdoor machine;

controlling the air conditioner to operate in a heating mode;

controlling the compressor to adjust to a preset first recovery frequency;

adjusting the opening of the throttling device so that the coil temperature of the outdoor heat exchanger is less than or equal to a preset temperature;

When the coil temperature is less than or equal to the preset temperature and lasts for a first preset time, control the air conditioner to switch to cooling mode;

Controlling the on-off valve to open and the throttling device to close to a minimum opening;

Wherein, the preset temperature is greater than the freezing temperature of the refrigerating machine oil.
The method for controlling oil pollution recovery in pipes of outdoor units according to claim 1, wherein after the step of "controlling the air conditioner to switch to cooling mode", the control method further includes:

Controlling the compressor to adjust to a preset second recovery frequency.
The method for controlling the recovery of oil in pipes of outdoor units according to claim 2, wherein the second recovery frequency is the highest limit frequency corresponding to the outdoor ambient temperature.
The control method for oil pollution recovery in pipes of outdoor units according to claim 1, characterized in that before the step of "adjusting the opening degree of the throttling device", the control method further includes:

Control the outdoor fan to run at the lowest speed.
The control method for oil pollution recovery in pipes of outdoor units according to claim 1, characterized in that before the step of "adjusting the opening degree of the throttling device", the control method further includes:

Control the indoor fan to run at the set speed.
The method for controlling oil pollution recovery in pipes of outdoor units according to claim 1, wherein after the step of "controlling the air conditioner to switch to cooling mode", the control method further includes:

The fan in the control room stops running.
The control method for oil pollution recovery in pipes of outdoor units according to claim 1, wherein the control method further comprises:

When entering the oil pollution recovery mode in the pipe of the outdoor unit, the outdoor anti-freezing protection function and the outdoor ambient temperature frequency limiting function are turned off.
According to claim 6, the control method for oil pollution recovery in pipes of outdoor units is characterized in that, after the step of "controlling the opening of the on-off valve and the closing of the throttling device to the minimum opening degree", the control method further include:

After the on-off valve is opened and the throttling device is closed to the minimum opening for a second preset period of time, the oil pollution recovery mode in the pipe of the outdoor unit is exited.
The method for controlling oil pollution recovery in pipes of outdoor units according to claim 8, wherein the step of "exiting the oil pollution recovery mode in pipes of outdoor units" further comprises:

Controlling the air conditioner to return to the operating mode before entering the oil pollution recovery mode in the outdoor unit pipe;

controlling the compressor to return to the frequency before entering the oil pollution recovery mode in the pipe of the outdoor unit;

controlling the throttling device to return to the opening before entering the oil pollution recovery mode in the pipe of the outdoor unit;

Control the on-off valve to close.
According to claim 9, the control method for oil pollution recovery in the pipe of the outdoor unit is characterized in that the step of "exiting the oil pollution recovery mode in the pipe of the outdoor machine" also includes:

Controlling the indoor fan to keep off;

When the coil temperature of the indoor heat exchanger reaches the anti-cold wind temperature, the indoor fan is controlled to start running.