WO2023284199A1 - 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, the air conditioner of the present application further comprises a recovery pipe, a first on-off valve, and a second on-off valve. The method comprises: controlling an air conditioner to operate for refrigeration, and 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; when the coil temperature is less than or equal to the preset temperature and lasts for a first preset duration, controlling the air conditioner to operate for heating; controlling the first on-off valve to close; and when the ratio of an air discharge pressure to an air suction pressure of the compressor is greater than or equal to a preset threshold and lasts for a second preset duration, opening the first on-off valve and the second on-off valve. By means of 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 sequentially connected through the refrigerant pipeline. The air conditioner also includes a recovery pipeline, a first on-off valve and a second on-off valve, The first on-off valve is arranged on the refrigerant pipeline between the throttling device and the indoor heat exchanger, and one end of the recovery pipeline is arranged on the throttling device and the first on-off valve. On the refrigerant pipeline between them, the other end of the recovery pipeline communicates with the suction port of the compressor, the second on-off valve is arranged on the recovery pipeline,

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 cooling operation of the air conditioner;

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 heating operation;

controlling the closing of the first on-off valve;

obtaining the discharge pressure and the suction pressure of the compressor every first interval;

When the ratio of the exhaust pressure to the suction pressure is greater than or equal to a preset threshold and lasts for a second preset duration, the first on-off valve and the second on-off valve are controlled to open.

In the preferred technical solution of the method for recovering oil in pipes of the indoor unit, the air conditioner further includes a third on-off valve, and the third on-off valve is arranged between the indoor heat exchanger and the four-way valve On the pipeline, the step of "controlling the air conditioner to switch to heating operation when the coil temperature is less than or equal to the preset temperature and lasts for a first preset time" further includes:

When the coil temperature is less than or equal to the preset temperature and lasts for the first preset time, controlling the third on-off valve to close;

controlling the first on-off valve to close after the third on-off valve is closed for a first preset delay time;

Controlling the compressor and the outdoor fan to stop;

After the compressor and the outdoor fan stop for a second preset delay time, the air conditioner is controlled to switch to heating operation.

In the preferred technical solution of the method for recovering oil in pipes of the indoor unit, before the step of "controlling the closing of the first on-off valve", the method further includes:

controlling the first on-off valve, the second on-off valve and the third on-off valve to open when the air conditioner is controlled to switch to heating operation;

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

The step of "controlling the closing of the first on-off valve" further includes:

After the compressor runs at the second recovery frequency for a third preset time period, the first on-off valve is controlled to be closed.

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 the indoor unit, the step of "adjusting the opening of the throttling device" further includes:

The opening degree of the throttling device is adjusted according to the preset exhaust gas 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 indoor fan to stop running, and control the outdoor fan to run at the highest speed.

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 method for recovering oil in pipes of indoor units, after the step of "controlling the opening of the first on-off valve and the second on-off valve", the method further includes:

After controlling the opening of the first on-off valve and the second on-off valve for a fourth preset period of time, exit the indoor unit pipe oil recovery mode.

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 outdoor fan to start and run;

The second on-off valve is controlled to be closed.

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 fifth 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.

It should be noted that, in the preferred technical solution of this application, the air conditioner includes a compressor, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchanger that are sequentially connected through a refrigerant pipeline. pipeline, the first on-off valve and the second on-off valve, the first on-off valve is set on the refrigerant pipeline between the throttling device and the indoor heat exchanger, and one end of the recovery pipeline is set on the throttling device and the first On the refrigerant pipeline between the on-off valves, the other end of the recovery pipeline communicates with the suction port of the compressor, and the second on-off valve is arranged on the recovery pipeline. Recycling command, enter the indoor unit pipe oil recovery mode; control the cooling operation of the air conditioner; control the compressor to adjust to the preset first recovery frequency; adjust the opening of the throttling device so that the coil temperature of the indoor heat exchanger is less than 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 operation; control the first on-off valve to close; obtain the compressor’s temperature at every first interval Exhaust pressure and suction pressure; when the ratio of exhaust pressure to suction pressure is greater than or equal to a preset threshold and lasts for a second preset duration, the first on-off valve and the second on-off valve are controlled to open.

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 perform cooling operation 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 oil, the freezing point is higher than that of the refrigerant, so in the refrigerant During the process of temperature drop, the oil stain first solidifies and precipitates from the refrigerant circulation, and adheres to the inner wall of the coil of the indoor heat exchanger, so that the oil stain 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, control the heat exchanger of the air conditioner to switch to the heating operation, and control the first on-off valve to close, so that the temperature and pressure of the refrigerant discharged by the compressor increase and gradually Accumulates in the coils of the indoor heat exchanger. When the ratio between the exhaust pressure and the suction pressure is greater than or equal to the preset threshold and lasts for the second preset time, the first on-off valve and the second on-off valve are opened, and the rapid flow of high-temperature and high-pressure refrigerant can be used to 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. First on-off valve ; 9, the second on-off valve; 10, the third on-off valve; 11, the reservoir.

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 this application, the terms "first", "second", "third", "fourth", "fifth", and "sixth" are only used for descriptive purposes, and cannot Read 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 11 . 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 in communication with the E port of the four-way valve 2, the S port of the four-way valve 2 is in communication with the inlet of the accumulator 11 through the refrigerant pipeline 6, and the outlet of the accumulator 11 is in communication 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 reservoir 11. The liquid reservoir 11 can store refrigerant, separate gas and liquid of refrigerant, filter oil, eliminate noise, and buffer refrigerant.

The air conditioner also includes a first on-off valve 8, a second on-off valve 9 and a recovery pipeline 7, the first on-off valve 8 and the second on-off valve 9 are preferably electromagnetic valves, and the first on-off valve 8 is Normally open valve, which is arranged on the refrigerant pipeline 6 between the throttling device 4 and the indoor heat exchanger 5, the second on-off valve 9 is a normally closed valve, which is arranged on the recovery pipeline 7, and the recovery pipeline 7 A copper tube with a smooth inner wall is used. The first end of the copper tube is set on the refrigerant pipeline 6 between the throttling device 4 and the first on-off valve 8, and the second end of the copper tube is set on the S of the four-way valve 2. On the refrigerant pipeline 6 between the interface and the inlet of the accumulator 11. Both the first on-off valve 8 and the second on-off valve 9 are communicatively connected with the controller of the air conditioner, so as to receive opening and closing signals issued by the controller. Of course, one or more of the above-mentioned on-off valves can also be replaced by electronically controlled valves such as electronic expansion valves.

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 cooling operation of the air conditioner.

In a possible implementation, the switch between cooling and heating 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 When powered on, the air conditioner runs 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 cooling mode, no adjustment is required, and the air conditioner is controlled to continue running; if the air conditioner is running in non-cooling mode, the air conditioner is controlled to switch to cooling 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 of Outdoor Ambient Temperature, First Recovery Frequency and Preset Exhaust Temperature

Outdoor ambient temperature (℃)	First recovery frequency (Hz)	Preset exhaust temperature (°C)
Tao≤16	50	Target Exhaust +20
16<Tao≤22	60	Target Exhaust +15
22<Tao≤29	70	Target Exhaust +10
29<Tao≤35	80	Target Exhaust +5
35＜Tao≤43	85	Target Exhaust +5
43<Tao≤52	78	target exhaust
Tao > 52	72	target exhaust

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 of the coil of the indoor heat exchanger can be detected by a temperature sensor installed on the coil of the indoor heat exchanger, and the opening of the electronic expansion valve can be adjusted to make the temperature of the indoor heat exchanger The coil temperature is less than or equal to the preset temperature. Since the freezing point of the refrigerant is much lower than the freezing point of the oil stain, the oil stain can be solidified and precipitated first when the coil temperature is less than or equal to the preset temperature. The preset temperature in this application can be set at -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 in a state of being less than or equal to the preset temperature by adjusting the opening degree of the electronic expansion valve.

In a possible implementation manner, the opening degree of the throttling device can be adjusted according to the preset exhaust gas temperature. Wherein, the preset exhaust temperature may be determined based on the correspondence between the outdoor ambient temperature and the preset exhaust temperature in Table 1 above. The target exhaust gas in the table is the target exhaust temperature of the compressor corresponding to the outdoor ambient temperature, and the determination of the target exhaust temperature is a conventional method in the art, and will not be repeated here. The applicant has found through experiments that when the expansion valve is adjusted according to the preset discharge temperature, the temperature of the indoor coil can be quickly dropped below the preset temperature.

Referring to Figure 1, when the air conditioner is in cooling operation, 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 the indoor air conditioner. on the inner wall of the heat exchanger coil.

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 period, control the air conditioner to switch to heating operation.

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 power on and off of the four-way valve, for example, the four-way valve is controlled to be powered on, and the air conditioner operates in heating.

S111. Control the first on-off valve to close.

In a possible implementation, the first on-off valve is controlled to close, and the refrigerant pipeline between the throttling device and the indoor heat exchanger is throttled. When the operation mode is switched to the heating mode, the first on-off valve is controlled to The valve is closed, at this time, as shown in Figure 2, the refrigerant in the outdoor heat exchanger and the refrigerant pipeline is discharged by the compressor and accumulated in the indoor heat exchanger.

S113. Obtain the discharge pressure and suction pressure of the compressor every first interval.

In a possible implementation manner, the discharge pressure of the compressor can be obtained by setting a pressure sensor at the discharge port of the compressor, and the suction pressure can be obtained by setting a pressure sensor at the suction port of the compressor. The first interval time can be any value from 1s to 10s, and the selection of this value is related to the change speed of the exhaust pressure and the suction pressure and the control precision to be achieved in this application. If the first recovery frequency is relatively large, the change speed of exhaust pressure and suction pressure is fast, or the application needs to achieve high control accuracy, the first interval time can be selected as 1s, 2s or shorter time, otherwise if The first recovery frequency is relatively small, the change speed of the exhaust pressure and the suction pressure is slow, or the control method of this application does not need to achieve high precision, then the first interval time can be selected as 9s, 10s or longer.

In the present application, preferably, the first interval time is selected as 5s, that is, after the first on-off valve is controlled to be closed, the discharge pressure and the suction pressure of the compressor are acquired every 5s.

In other non-preferred implementations, the method of obtaining the exhaust pressure and the suction pressure is not the only one, and those skilled in the art can adjust them. This adjustment does not deviate from the principle of the application. A pressure sensor is installed on the coil of the heat exchanger to obtain the exhaust pressure, and a pressure sensor is installed on the coil of the outdoor heat exchanger to obtain the suction pressure.

S115. When the ratio of the exhaust pressure to the suction pressure is greater than or equal to a preset threshold and lasts for a second preset duration, control the first on-off valve and the second on-off valve to open.

After the above parameters are obtained, the ratio between the exhaust pressure and the suction pressure is calculated, and the ratio is compared with the preset threshold and the duration of the ratio being less than the preset threshold. In this application, the preset threshold can be any value in 6-10, and in this application it is 8, and the second preset duration can be any value in 3-10s, and in this application it is 5s. When the ratio between the discharge pressure and the suction pressure is greater than or equal to the preset threshold and lasts for a second preset time, the refrigerant has accumulated in the indoor heat exchanger and the pressure of the discharge port of the compressor rises to a higher level at this time value, meet the oil pollution recovery conditions, and can carry out oil pollution recovery operations. When the above conditions are met, the first on-off valve and the second 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 quickly impacts the coil of the indoor heat exchanger, and the oil stain temporarily stored inside the coil is melted, and the high-temperature refrigerant directly flows back to the liquid storage through the recovery pipeline The filter is intercepted and filtered by the filter inside the reservoir to achieve the purpose of oil recovery.

It can be seen that by controlling the air conditioner to perform cooling operation 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 oil, the freezing point is higher than that of the refrigerant, so When the temperature of the refrigerant drops, the oil is first solidified and precipitated from the refrigerant circulation, and adheres to the inner wall of the coil of the indoor heat exchanger, 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, control the heat exchanger of the air conditioner to switch to the heating operation, and control the first on-off valve to close, so that the temperature and pressure of the refrigerant discharged by the compressor increase and gradually Accumulates in the coils of the indoor heat exchanger. When the ratio between the exhaust pressure and the suction pressure is greater than or equal to the preset threshold and lasts for the second preset time, the first on-off valve and the second on-off valve are opened, and the rapid flow of high-temperature and high-pressure refrigerant can be used to 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.

1, in a possible implementation, the air conditioner also includes a third on-off valve 10, the third on-off valve 10 is preferably a solenoid valve, the third on-off valve 10 is a normally open valve, which is set at On the refrigerant pipeline 6 between the indoor heat exchanger 5 and the four-way valve 2 , the third on-off valve 10 is communicatively connected with the controller of the air conditioner to receive opening and closing signals issued by the controller. Obviously, the third on-off valve 10 can also be replaced by an electronically controlled valve such as an electronic expansion valve.

On the basis of setting the third on-off valve, step S109 further includes: when the coil temperature is less than or equal to the preset temperature and lasts for the first preset time, controlling the third on-off valve to close; And after the first preset delay time, close the first on-off valve; control the compressor and the outdoor fan to stop; after the compressor and the outdoor fan stop and last the second preset delay time, control the air conditioner to switch to heating operation .

Specifically, the first preset delay time can be any value from 10s to 1min, and in this application it is 30s, and the second preset delay time can be any value from 1min to 5min, and 3min is selected in this application. When the coil temperature is less than or equal to the preset temperature and lasts for the first preset time, the third on-off valve is controlled to close, so as to throttle the refrigerant pipeline between the indoor heat exchanger and the four-way valve. At this time, the refrigerant discharged from the compressor is accumulated in the indoor heat exchanger after passing through the outdoor heat exchanger and throttling device. After the third on-off valve is closed for 30 seconds, close the first on-off valve to throttle the refrigerant pipeline between the indoor heat exchanger and the throttling device, so that the refrigerant discharged from the compressor is basically accumulated in the indoor heat exchange In the device, that is, between the first on-off valve and the third on-off valve. At this time, control the compressor and outdoor fan to stop, and maintain this state for 3 minutes. Since the temperature of the refrigerant at this time is low, the coil of the indoor heat exchanger can be fully cooled, and the oil and refrigerant can be completely separated. After 3 minutes, the air conditioner will switch to heating operation, which can improve the oil recovery effect.

In a possible implementation manner, before step S111, the method further includes: controlling the first on-off valve, the second on-off valve and the third on-off valve to open when controlling the air conditioner to switch to heating operation; The compressor is adjusted to the preset second recovery frequency; the step of "controlling the closing of the first on-off valve" further includes: after the compressor runs at the second recovery frequency for a third preset period of time, controlling the first on-off valve to close.

Specifically, when the air conditioner switches to the heating operation, the first on-off valve, the second on-off valve and the third on-off valve are controlled to open. Circulation between the heater and the recovery line. 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. Wherein, the manner of obtaining the outdoor ambient temperature is a conventional means in the field, and will not be repeated here. The third preset duration can be any value from 10s to 1min. In this application, it is 30s. When the compressor runs at the second recovery frequency for the third preset duration, the refrigerant will flow through the compressor, indoor heat exchanger and recovery pipeline The cycle is realized in the middle, and the oil pollution recovery has been prepared. At this time, the first on-off valve is controlled to be closed.

In a possible implementation, before the step of "adjusting the opening degree of the throttling device", the method further includes: controlling the indoor fan to stop running, and controlling the outdoor fan to run at the highest speed. 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. Before adjusting the opening 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 heat transfer of the refrigerant indoors The evaporative effect in the appliance allows the indoor coil to cool down to the preset temperature more quickly.

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. After ensuring the first cooling operation to make the coil temperature less than or equal to the preset temperature, then switching to heating operation and closing the first on-off valve to throttle, and through exhaust On the premise that the ratio of air pressure to suction pressure controls the opening of the first on-off valve and the second on-off valve, 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 at or below the preset temperature, the operating frequency of the compressor, the opening degree of the electronic expansion valve, and the opening of the third on-off valve can be controlled in the above control mode. One or more of the off, the speed of the indoor fan and the speed of the outdoor fan are omitted.

In a possible implementation manner, the method further includes: after the first on-off valve and the second on-off valve are opened for a fourth preset period of time, exiting the oil pollution recovery mode in the pipe of the indoor unit. Wherein, the fourth preset duration can be any value in 30s-120s, and in this application, it is preferably 60s. When the first on-off valve and the second on-off valve are open for 60s, the high-temperature and high-pressure refrigerant has circulated several times, which is enough to produce a better oil recovery effect in the pipe, so the first on-off valve and the second on-off valve When it is turned on for 60s, exit the oil pollution recovery mode in the indoor unit pipe.

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 outdoor The fan is turned on, the indoor fan is controlled to be turned on and the air deflector of the indoor unit is controlled to send air upward, the throttling device is controlled to be adjusted to the maximum opening, and the second 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 cooling operation of the air conditioner before entering the indoor unit duct oil recovery mode as an example. After the indoor unit duct oil recovery mode 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 is opened to the maximum opening degree, and the second on-off valve is controlled to be closed, so that the refrigerant flows in the normal cooling mode flow direction. 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 is opened to the maximum opening. 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 is opened to the maximum opening. temperature, so that the refrigerant quickly fills 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 the fifth 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 fifth preset duration can be any value from 20s to 60s. In this application, it is preferably 30s. When the indoor fan is turned on and the air deflector is blowing 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 sixth preset time period, 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 sixth preset duration can be any value within 1min-5min, and it is preferably 3min in this application. When the electronic expansion valve maintains the maximum opening and operates 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 indoor fan may be controlled to start running after it is acquired that the coil temperature of the indoor heat exchanger has dropped to a temperature suitable for the cooling mode.

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 in cooling operation, 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 determine the preset exhaust temperature according to the current outdoor ambient temperature, adjust the opening degree of the throttling device according to the preset exhaust temperature, 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 third on-off valve to close, and close the first on-off valve 30 seconds after the third on-off valve is closed, and simultaneously turn off the compressor and the outdoor fan.

Next, step S209 is executed to judge whether the compressor and outdoor fan shutdown duration t2≥3min is established, and if established, execute step S211; otherwise, when not established, return to execute step S209.

S211, control the heating operation of the air conditioner, control the compressor to start and adjust to the maximum frequency limit corresponding to the outdoor ambient temperature, and control the first on-off valve, the second on-off valve and the third on-off valve to open simultaneously.

Next, step S213 is executed to determine whether the duration t3≥30s of the compressor running at the maximum frequency is established; if the judgment result is true, then step S215 is executed; otherwise, when the judgment result is not established, then return to continue to execute step S213.

S215, close the first on-off valve, and detect the discharge pressure Pd and the suction pressure Ps every 5s, and calculate the ratio between them.

Next, execute S217 to determine whether the ratio Pd/Ps≥8 of the exhaust pressure Pd to the intake pressure Ps and the duration t4≥5s are established. If yes, execute step S219; otherwise, if not, return to execute step S217.

S219, open the first on-off valve.

Next, step S221 is executed to determine whether the opening duration of the first on-off valve t5≥60s is established, and if established, execute step S223; otherwise, if not established, execute step S221.

S223, exit the oil pollution recovery mode in the indoor unit pipe, specifically, control the cooling operation of the air conditioner, control the electronic expansion valve to open to the maximum opening, control the indoor fan to turn on and the air guide plate to blow upward, control the outdoor fan to turn on, and control the compressor to return to The frequency before entering the oil recovery mode in the indoor unit pipe controls the closing of the second on-off valve.

Further, when the indoor fan is turned on for 30 seconds, the indoor fan and the wind deflector are controlled to return to the operating state before entering the oil pollution recovery mode in the indoor unit pipe. When the throttling device is opened to the maximum opening for 3 minutes, control the electronic expansion valve to return to the opening before entering the oil pollution recovery mode in the indoor unit pipe, and then the air conditioner returns to the cooling mode before entering the oil pollution recovery mode in the indoor unit pipe run.

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, which is applied to air conditioners, characterized in that the air conditioner includes a compressor, a four-way valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchange unit sequentially connected through a refrigerant pipeline. The air conditioner also includes a recovery pipeline, a first on-off valve and a second on-off valve, the first on-off valve is arranged in the refrigerant pipe between the throttling device and the indoor heat exchanger On the road, one end of the recovery pipeline is set on the refrigerant pipeline between the throttling device and the first on-off valve, and the other end of the recovery pipeline communicates with the suction port of the compressor, The second on-off valve is arranged on the recovery pipeline,

   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 cooling operation of the air conditioner;

   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 heating operation;

   controlling the closing of the first on-off valve;

   obtaining the discharge pressure and the suction pressure of the compressor every first interval;

   When the ratio of the exhaust pressure to the suction pressure is greater than or equal to a preset threshold and lasts for a second preset duration, the first on-off valve and the second on-off valve are controlled to open.
2. The method for recovering oil in pipes of indoor units according to claim 1, wherein the air conditioner further includes a third on-off valve, and the third on-off valve is arranged between the indoor heat exchanger and the four On the refrigerant pipeline between the through valves, the step of "controlling the air conditioner to switch to heating operation when the coil temperature is less than or equal to the preset temperature for a first preset time" further includes:

   When the coil temperature is less than or equal to the preset temperature and lasts for the first preset time, controlling the third on-off valve to close;

   After the third on-off valve is closed and lasts for a first preset delay time, the first on-off valve is controlled to be closed;

   Controlling the compressor and the outdoor fan to stop;

   After the compressor and the outdoor fan stop for a second preset delay time, the air conditioner is controlled to switch to heating operation.
3. The method for recovering oil in pipes of indoor units according to claim 2, wherein before the step of "controlling the closing of the first on-off valve", the method further comprises:

   controlling the first on-off valve, the second on-off valve and the third on-off valve to open when the air conditioner is controlled to switch to heating operation;

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

   The step of "controlling the closing of the first on-off valve" further includes:

   After the compressor runs at the second recovery frequency for a third preset time period, the first on-off valve is controlled to be closed.
4. The method for recovering oil in pipes of indoor units according to claim 3, wherein the second recovery frequency is the highest limit frequency corresponding to the outdoor ambient temperature.
5. The method for recovering oil in pipes of indoor units according to claim 1, wherein the step of "adjusting the opening of the throttling device" further comprises:

   The opening degree of the throttling device is adjusted according to the preset exhaust gas temperature.
6. 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 indoor fan to stop running, and control the outdoor fan to run at the highest speed.
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 3, characterized in that, after the step of "controlling the opening of the first on-off valve and the second on-off valve", the method further comprises:

   After controlling the opening of the first on-off valve and the second on-off valve for a fourth preset period of time, exit the indoor unit pipe oil recovery mode.
9. The method for recovering oil pollution in pipes of indoor units according to claim 8, wherein the step of "exiting the oil pollution recovery mode 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 outdoor fan to start and run;

   The second on-off valve is controlled to be closed.
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 fifth 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.

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