WO2023279615A1 - In-pipe greasy dirt recovery method for indoor unit - Google Patents

Abstract

The present invention relates to the technical field of air conditioner self-cleaning, and in particular to an in-pipe greasy dirt recovery method for an indoor unit. The present application aims to solve the problem of how to implement in-pipe greasy dirt recovery of the indoor unit. For this purpose, an air conditioner of the present application further comprises a recovery pipe having one end communicated with an outlet of an outdoor heat exchanger and the other end communicated with an air suction port of a compressor, and the recovery pipe is provided with an on-off valve. The method comprises: entering an in-pipe greasy dirt recovery mode of an indoor unit; controlling an air conditioner to run a refrigeration mode; controlling a compressor to be adjusted to a preset first recovery frequency; adjusting the opening degree of a throttling device, so that a coil temperature of an indoor heat exchanger is less than or equal to a preset temperature; after the coil temperature is less than or equal to the preset temperature and lasts for a first preset duration, controlling the air conditioner to be switched to a heating mode; and controlling the on-off valve to open and controlling the throttling device to open to a preset opening degree. According to the method of the present application, in-pipe greasy dirt recovery of the indoor unit can be implemented, and the problem of in-pipe dirty blockage of the indoor heat exchanger is solved.

Description

Indoor unit pipe oil recovery method technical field

The invention relates to the technical field of self-cleaning of air conditioners, in particular to a method for recovering oil stains in pipes of indoor units.

Background technique

For the indoor unit of the air conditioner, the refrigeration oil will participate in the circulation along with the refrigerant during use. During the circulation process, the refrigeration oil will appear carbon and impurities. These oils will flow to the hairpin tube of the indoor heat exchanger along with the refrigerant. Due to the current 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 air conditioning refrigeration effect worse.

Correspondingly, there is a need in the art for a new method for recovering oil in pipes of indoor units 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, in order to solve the problem of how to realize the oil pollution recovery in the pipe of the indoor unit, the application provides a method for recovering oil pollution in the pipe of the indoor unit, which is applied to an air conditioner, and the air conditioner includes A compressor, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchanger are connected through a refrigerant pipeline. The air conditioner also includes a recovery pipeline, and one end of the recovery pipeline exchanges heat with the outdoor The outlet of the device is connected, the other end of the recovery pipeline is connected with the suction port of the compressor, and an on-off valve is arranged on the recovery pipeline, and the on-off valve is a normally closed valve.

The methods include:

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

controlling the air conditioner to operate in a cooling 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 indoor 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 a heating mode;

Controlling the opening of the on-off valve and opening of the throttling device to a preset opening degree;

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

In the preferred technical solution of the method for recovering oil pollution in pipes of indoor units, after the step of "controlling the air conditioner to switch to heating mode", the method further includes:

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

In the preferred technical solution of the method for recovering oil in pipes of the indoor unit, the second recovery frequency is the highest limit frequency corresponding to the outdoor ambient temperature.

In the preferred technical solution of the above-mentioned method for recovering oil in pipes of indoor units, before the step of "adjusting the opening of the throttling device", the method further includes:

Control the outdoor fan to run at the highest speed.

In the preferred technical solution of the above-mentioned method for recovering oil in pipes of indoor units, the preset opening is the maximum opening of the throttling device.

In the preferred technical solution of the above-mentioned method for recovering oil in pipes of indoor units, before the step of "adjusting the opening of the throttling device", the method further includes:

The fan in the control room stops running.

In the preferred technical solution of the method for recovering oil pollution in the pipe of the above-mentioned indoor unit, the method also includes:

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

In the preferred technical solution of the above-mentioned method for recovering oil in pipes of indoor units, after the step of "controlling the opening of the on-off valve and the opening of the throttling device to a preset opening degree", the method further includes:

After the on-off valve is opened and the throttling device is opened to a preset opening for a second preset period of time, the indoor unit tube oil recovery mode is exited.

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

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

Controlling the compressor to return to the frequency before entering the oil pollution recovery mode in the indoor unit pipe;

Control the on-off valve to close.

In the preferred technical solution of the above-mentioned method for recovering oil in pipes of indoor units, the step of "exiting the mode of recovering oil in pipes of indoor units" also includes:

Control the indoor fan to turn on, and control the air deflector of the indoor unit to send air upward;

After the air deflector is controlled to send air upward for a third preset time period, the indoor fan and the air deflector are controlled to return to the operating state before entering the oil pollution recovery mode in the indoor unit pipe.

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 outlet 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 set on the recovery pipeline, and the on-off valve is a normally closed valve. The method includes : Responding to the received instruction of recovering the oil pollution in the pipe of the indoor unit, enter the oil pollution recovery mode in the indoor unit pipe; control the air conditioner to run in the cooling mode; control the compressor to adjust to the preset first recovery frequency; adjust the opening of the throttling device degrees, so that the coil temperature of the indoor 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 heating mode; control the on-off valve to open . The throttling device is opened to a preset opening degree; 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 oil pollution in the pipe of the indoor unit, and solve the problem of dirty blockage in the pipe of the indoor heat exchanger. Specifically, by controlling the air conditioner to run in cooling mode first, and adjusting the opening of the throttling device so that the coil temperature of the indoor 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 the refrigeration oil is higher than that of the oil, so the oil in the refrigeration 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 indoor heat exchanger. The engine oil is circulated back to the compressor along with the refrigerant, so that the oil in the refrigerant is separated and temporarily stored in the coil of the indoor 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 the heating mode, and the on-off valve and the throttling device are opened, so that the rapid flow of high-temperature and high-pressure refrigerant can impact the indoor heat exchanger. Inside the coil of the heater, the oil stain temporarily stored inside the coil is melted by high temperature and returns directly to the interior of the compressor along with the refrigerant through the recovery pipeline to realize the oil recovery of the indoor 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 recovering the oil pollution in the pipe of the indoor 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 cooling mode;

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

Fig. 3 is the flowchart of the oil pollution recovery method in the pipe of the indoor unit of the present application;

Fig. 4 is a logic diagram of a possible implementation process of the method for recovering oil stains in pipes of indoor 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", "third" and "fourth" 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 clearly 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 cooling 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 compressor 1 communicates with the P interface of four-way valve 2 through refrigerant pipeline 6, and the C interface of four-way valve 2 communicates with the inlet of outdoor heat exchanger 3 through 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 indoor heat exchanger 5 through the refrigerant pipeline 6, and the outlet of the indoor heat exchanger 5 passes through the refrigerant pipeline 6 is connected with the E 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 indoor heat exchanger 5 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 indoor heat exchanger 5 . 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 pollution in the pipe of the indoor unit of this embodiment will be described in conjunction with the structure of the above-mentioned air conditioner, 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.

In the following, with reference to Fig. 1 , Fig. 2 and Fig. 3 , the method for recovering the oil pollution in the pipe of the indoor unit of the present application will be introduced. Among them, Fig. 2 is a system diagram of the air conditioner of the present application in heating mode; Fig. 3 is a flow chart of the method for recovering oil in pipes of the indoor 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 indoor unit, the oil pollution recovery method in the indoor unit of the present application includes:

S101. In response to receiving an instruction to recover the oil in the pipe of the indoor unit, enter a mode of recovering the oil in the pipe of the indoor unit.

In a possible implementation, the instruction to recover the oil pollution in the pipe of the indoor unit can be actively issued by the user, 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 in 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 instruction to recover the oil in the pipe of the indoor unit, it switches the operation mode to the oil recovery mode in the indoor unit pipe, and starts to recover the oil in the pipe of the coil of the indoor unit. Wherein, the oil pollution recovery mode in the pipe can be a computer program, which is pre-stored in the air conditioner. When this mode is operated, 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 indoor unit pipe can also be automatically issued when the air conditioner meets certain entry conditions. For example, when the cumulative working time of the air conditioner reaches the preset time, an instruction to recover the oil pollution in the indoor unit pipe is issued, and the preset time length For example, it can be 20h-40h.

S103. Control the air conditioner to run in cooling 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 runs in cooling mode, When powered on, the air conditioner operates in heating mode. In this embodiment, after entering the oil pollution recovery mode in the indoor unit pipe, if the air conditioner is running in the cooling mode, no adjustment is required, and the air conditioner is controlled to continue running; if the air conditioner is running in the non-cooling mode, the air conditioner is controlled to switch to the cooling mode run.

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

Outdoor ambient temperature (℃)	First recovery frequency (Hz)
Tao≤16	50
16<Tao≤22	60
22<Tao≤29	70
29<Tao≤35	80
35＜Tao≤43	85
43<Tao≤52	78
Tao > 52	72

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

In a possible implementation, the temperature sensor detects the coil temperature of the indoor heat exchanger, and dynamically adjusts the opening of the electronic expansion valve so that the coil temperature of the indoor 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, to ensure fluidity, the freezing point of refrigerating machine oil is below -50°C. The preset temperature can be set from -5°C to -25°C, and in this application, the preset temperature can be -10°C. That is to say, the coil temperature of the indoor heat exchanger is less than or equal to the preset temperature as the control purpose, and the coil temperature of the indoor heat exchanger is always less than or equal to The status of the preset temperature.

Referring to Figure 1, when the air conditioner is running in cooling mode, keep the coil temperature of the indoor heat exchanger at a temperature less than or equal to -10°C. At this time, the oil in the indoor heat exchanger will be stripped from the refrigerant circulation and attached to On the inner wall of the coil of the indoor heat exchanger.

Certainly, in other implementation manners, the coil temperature of the indoor 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. After the coil temperature is less than or equal to the preset temperature for a first preset time, control the air conditioner to switch to the heating 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 -10°C and lasts for 10 minutes, the oil in the indoor 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 four-way valve to be powered on and off, for example, the four-way valve is controlled to be powered on, and the air conditioner operates in the heating mode.

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

In a possible implementation manner, when the operation mode is switched to the heating mode, the throttling device and the on-off valve are controlled to open. 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 indoor heat exchanger, and the high-temperature and high-pressure refrigerant quickly impacts the coil of the indoor heat exchanger, and the oil that is temporarily stored in 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. More preferably, the throttling device is controlled to open to the maximum opening degree, so that the high-temperature and high-pressure refrigerant can pass quickly, reduce the pressure drop during the flow of the refrigerant, and improve the oil recovery effect in the pipe.

It can be seen that by controlling the air conditioner to run in cooling mode first, and adjusting the opening of the throttling device so that the coil temperature of the indoor 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 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 temperature of the refrigerant drops, and adheres to the inner wall of the coil of the indoor heat exchanger. 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 indoor 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 the heating mode, and the on-off valve and the throttling device are opened, so that the rapid flow of high-temperature and high-pressure refrigerant can impact the indoor heat exchanger. Inside the coil of the heater, the oil stain temporarily stored inside the coil is melted by high temperature and returns directly to the interior of the liquid receiver through the recovery pipeline along with the refrigerant to realize the oil recovery of the indoor 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 indoor heat exchanger, and realize the flushing of the indoor heat exchanger by the high-temperature and high-pressure refrigerant. Finally, without going through the outdoor heat exchanger again, the oil is directly brought back to the liquid receiver for recovery and filtration, and then compressed and discharged by the compressor again, which reduces the flow stroke of the 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 the heating 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 outdoor fan to run at the highest speed. Specifically, before adjusting the opening degree of the throttling device, by controlling the outdoor fan to run at the highest speed, the heat exchange effect between the refrigerant and the environment in the outdoor heat exchanger can be improved, thereby reducing the temperature and pressure of the refrigerant, and improving the temperature of the refrigerant. The evaporation effect in the indoor heat exchanger causes the indoor coil to cool down to the preset temperature more quickly.

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 stop running. Specifically, before adjusting the opening degree of the throttling device, the indoor fan is first controlled to stop running, so as to reduce the heat exchange effect between the indoor heat exchanger and the air, thereby speeding up the temperature reduction of the indoor coil and reducing the oil pollution. recycling efficiency.

In a possible implementation manner, the method further includes: when entering the oil pollution recovery mode in the pipe of the indoor unit, turning off the indoor anti-freezing protection function and the outdoor ambient temperature frequency limiting function. Since the coil temperature of the indoor 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, so during the cooling operation, turn off the indoor anti-freeze protection function and the outdoor ambient temperature frequency limit 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 indoor unit pipe is not unique. On the premise of ensuring that the cooling mode is operated first to make the coil temperature less than or equal to the preset temperature, and then converted to the heating mode and the on-off valve and throttling device are opened , those skilled in the art can adjust the control method. For example, on the premise that the coil temperature of the indoor heat exchanger can be kept below or equal to 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. For another example, when the in-pipe oil pollution recovery mode is implemented, the speed of the outdoor fan can be determined according to the outdoor ambient temperature, and then the operation of the outdoor fan can be controlled.

In a possible implementation, the method further includes: after the on-off valve is opened and the throttling device is opened to a preset opening for a second preset period of time, exiting the indoor unit pipe oil recovery mode. 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, so when the throttling device and the on-off valve are opened for 5 minutes, it will exit the indoor unit pipe Oil recovery mode.

Specifically, the step of exiting the oil pollution recovery mode in the indoor unit pipe further includes: controlling the air conditioner to return to the operating mode before entering the oil pollution recovery mode in the indoor unit pipe, controlling the compressor to return to the frequency before entering the oil pollution recovery mode in the indoor unit pipe, controlling the indoor The fan is turned on, and the air deflector of the indoor unit is controlled to send air upward, the throttling device is controlled to maintain the maximum opening, and the on-off valve is controlled to be closed. After the oil pollution recovery process in the pipe is completed, the air conditioner needs to return to the operation mode before the oil pollution recovery in the pipe, so as to continue to adjust the indoor temperature. Take the air conditioner running in the cooling mode before entering the oil pollution recovery mode in the indoor unit pipe as an example. After the oil pollution recovery mode in the indoor unit pipe is executed, it needs to switch back to the cooling mode. At this time, control the four-way valve to turn off the power to restore the cooling mode, control the compressor to recover from the second recovery frequency to the frequency before entering the oil pollution recovery mode in the indoor unit pipe, control the indoor fan to turn on and the air deflector of the indoor unit to send air upwards, and control The electronic expansion valve maintains the maximum opening and controls the on-off valve to close, so that the refrigerant flows in the normal cooling mode. Wherein, when the indoor fan is turned on, the air deflector of the indoor unit blows air upwards, so as to prevent the bad user experience caused by the high temperature of the indoor heat exchanger coil due to the high temperature of the indoor heat exchanger coil when the air conditioner just switches to cooling mode. Among them, the throttling device maintains the maximum opening degree. Since the refrigerant circulates between the compressor and the indoor heat exchanger during the operation of the oil pollution recovery mode in the indoor unit pipe, resulting in the lack of refrigerant in the outdoor heat exchanger, the throttling device maintains the maximum opening degree. Make the refrigerant quickly fill the outdoor heat exchanger, so as to realize the normal circulation of the refrigerant as soon as possible.

Correspondingly, after the air deflector is controlled to send air upwards for a third preset period of time, the indoor fan and the air deflector are controlled to return to the operating state before entering the oil pollution recovery mode in the indoor unit pipe. Wherein, the third preset duration can be any value from 20s to 1min. In this application, it is preferably 30s. When the indoor fan is turned on and the air guide plate blows air upwards for 30s, the temperature of the coil of the indoor heat exchanger has dropped to the level comparable to that of the cooling system. At this time, the indoor fan and the air deflector are controlled to return to the operating mode before entering the oil pollution recovery mode in the indoor unit pipe, so as to meet the cooling needs of the user.

Correspondingly, after the throttling device is controlled to maintain the maximum opening for a fourth preset period of time, the throttling device is controlled to return to the opening before entering the oil pollution recovery mode in the indoor unit pipe. Among them, the fourth preset time length can be any value within 1min-5min, preferably 3min in this application, when the electronic expansion valve maintains the maximum opening and runs for 3min, the refrigerant circulation has tended to be stable, at this time the electronic expansion valve is controlled to return to The opening degree before entering the oil pollution recovery mode in the indoor unit pipe, so that the air conditioner can completely restore the cooling parameters before entering the indoor unit pipe oil recovery mode and continue to operate.

Of course, the way to exit the oil pollution recovery mode in the indoor unit pipe is not limited to the above-mentioned one. On the premise that the air conditioner can be restored to the operating state before entering the oil pollution recovery mode in the indoor unit pipe, those skilled in the art can freely choose specific control methods. 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 indoor unit pipe; for another example, after the temperature of the coil tube of the indoor heat exchanger has dropped to a temperature suitable for the cooling mode, the indoor fan can be controlled again. The fan starts running.

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 indoor units of the present application.

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

First, step S201 is executed, the air conditioner enters the oil pollution recovery mode in the indoor unit pipe, that is, the air conditioner is controlled to maintain the cooling mode operation, the compressor is controlled to adjust to the first recovery frequency, the indoor fan is controlled to stop running, and the outdoor fan is controlled to run at the maximum speed.

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

Next, step S205 is executed to judge whether the coil temperature Tp of the indoor heat exchanger Tp≤-10°C and the duration t1≥10min are simultaneously established, and 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 heating mode, control the compressor to adjust to the highest limit frequency corresponding to the outdoor ambient temperature, control the solenoid valve to open, and the electronic expansion valve to open to the maximum opening.

Next, step S209 is executed, and it is judged whether the duration t2≥5min of the electronic expansion valve and the electromagnetic valve being jointly opened is established; if the judgment result is true, then step S211 is executed; otherwise, when the judgment result is not established, then return to continue execution of step S209.

S211, exit the oil pollution recovery mode in the pipe, specifically, control the air conditioner to operate in the cooling mode, control the electronic expansion valve to maintain the maximum opening, control the indoor fan to turn on and the air deflector to blow upward, and control the compressor to return to the oil pollution recovery mode entering the indoor unit pipe Before the frequency, the control solenoid valve is closed.

Next, step S213 is executed to judge whether the time t3≥30s for the indoor fan to be turned on is established; when the judgment result is established, execute step S215, otherwise, return to continue executing step S213;

S215, controlling the indoor fan and the air deflector to restore the operating state before entering the oil pollution recovery mode in the indoor unit pipe.

Next, step S217 is executed to determine whether the duration of the electronic expansion valve maintaining the maximum opening degree t4≥3min is established; if the judgment result is true, execute step S219; otherwise, if the judgment result is not established, return to continue to execute step S217.

S219, controlling the electronic expansion valve to return to the opening degree before entering the oil pollution recovery mode in the indoor unit pipe, so far the air conditioner returns to the cooling mode operation before entering the oil pollution recovery mode in the indoor 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. Without departing from the principle of the present application, 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 application.

Claims (10)

1. A method for recovering oil in pipes of indoor units, applied to air conditioners, 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 exchanger , the air conditioner also includes a recovery pipeline, one end of the recovery pipeline communicates with the outlet of the outdoor heat exchanger, the other end of the recovery pipeline communicates with the suction port of the compressor, the An on-off valve is arranged on the recovery pipeline, and the on-off valve is a normally closed valve.

   The methods include:

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

   controlling the air conditioner to operate in a cooling 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 indoor 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 a heating mode;

   Controlling the opening of the on-off valve and opening of the throttling device to a preset opening degree;

   Wherein, the preset temperature is greater than the freezing temperature of the refrigerating machine oil.
2. The method for recovering oil pollution in pipes of indoor units according to claim 1, characterized in that, after the step of "controlling the air conditioner to switch to heating mode", the method further comprises:

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

   Control the outdoor fan to run at the highest speed.
5. The method for recovering oil in pipes of indoor units according to claim 1, wherein the preset opening is the maximum opening of the throttling device.
6. The method for recovering oil in pipes of indoor units according to claim 1, wherein before the step of "adjusting the opening of the throttling device", the method further comprises:

   The fan in the control room stops running.
7. The method for recovering oil pollution in pipes of indoor units according to claim 1, characterized in that the method further comprises:

   When entering the oil pollution recovery mode in the pipe of the indoor unit, the indoor anti-freezing protection function and the outdoor ambient temperature frequency limiting function are turned off.
8. The method for recovering oil in pipes of indoor units according to claim 6, characterized in that after the step of "controlling the opening of the on-off valve and the opening of the throttling device to a preset opening degree", the method further includes :

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

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

   Controlling the compressor to return to the frequency before entering the oil pollution recovery mode in the indoor unit pipe;

   Control the on-off valve to close.
10. The method for recovering oil pollution in pipes of indoor units according to claim 9, wherein the step of "exiting the oil pollution recovery mode in pipes of indoor units" further comprises:

    Control the indoor fan to turn on, and control the air deflector of the indoor unit to send air upward;

    After the air deflector is controlled to send air upward for a third preset time period, the indoor fan and the air deflector are controlled to return to the operating state before entering the oil pollution recovery mode in the indoor unit pipe.

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