Refrigerant recovery system, air conditioner and control method thereof

Abstract

The invention provides a refrigerant recovery system, an air conditioner and a control method of the refrigerant recovery system. The four-way valve comprises a first outlet, a second outlet, a third outlet and a fourth outlet, the first outlet is communicated with an outlet of the compressor through a fourth branch, the second outlet is communicated with an inlet of the heat exchanger through a third branch, and the third outlet is communicated with an inlet of the gas-liquid separator through a sixth branch; an outlet of the gas-liquid separator communicates with an inlet of the compressor through a seventh branch, and an outlet of the heat exchanger and a fourth outlet communicate with the indoor unit. The refrigerant recovery system further comprises a second branch, one end of the second branch is communicated with the sixth branch, the other end of the second branch is communicated with the fourth branch, a second valve body is arranged on the second branch, and a first valve body is arranged on the third branch. According to the air conditioner, the technical problem that in the prior art, after the refrigerant of the air conditioner is recycled, the refrigerant exists in all components of the outdoor unit of the air conditioner can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioners, and in particular relates to a refrigerant recovery system, an air conditioner, and a control method thereof. Background Art

[0002] In actual use, air conditioning systems often encounter various problems that require refrigerant recovery, such as when the indoor and outdoor units need to be replaced, or when system components such as valve bodies are damaged and need to be repaired and replaced. At this time, the usual practice is to manually control the stop valves on the outdoor unit gas pipe and liquid pipe to achieve refrigerant recovery. The operation method is to switch the unit to refrigeration mode and start the machine, first close the liquid pipe stop valve, and then immediately close the gas pipe stop valve after the unit is shut down for protection. There are also some technologies that support automatic recovery, adding valve bodies such as electric ball valves to the gas pipe and liquid pipe stop valves of the outdoor unit. The operation is similar to manual, first close the valve on the liquid pipe, and then close the gas pipe stop valve after protection or after running for a period of time. However, both of these recovery methods have obvious disadvantages. The refrigerant is recovered to the outdoor unit, but these refrigerants are distributed in the outdoor heat exchanger, vapor-liquid separator, liquid storage device (if configured) and outdoor unit pipelines. Such recovery effect can only meet the maintenance and replacement of non-outdoor unit parts. When the outdoor unit valve body and compressor are replaced, the refrigerant filled inside cannot support work such as hot fire welding.

[0003] Therefore, new technologies are urgently needed that can recover the refrigerant to the smallest location range. The vapor-liquid separator has a large volume and is the main storage location. If most of the refrigerant is recovered to the vapor-liquid separator, when most of the components of the outdoor unit are replaced, there will be no trouble in operating with refrigerant.

[0004] Since the refrigerant in the air conditioner in the prior art is recovered, the recovered refrigerant is distributed in most of the pipes inside the outdoor unit, and the main components of the outdoor unit still have refrigerant after the recovery, which leads to technical problems such as inconvenience in repairing the outdoor unit. Therefore, the present invention studies and designs a refrigerant recovery system, an air conditioner, and a control method thereof. Summary of the invention

[0005] Therefore, the present invention provides a refrigerant recovery system, an air conditioner, and a control method thereof, which can solve the technical problem in the prior art that refrigerant exists in all components of the air conditioner outdoor unit after the refrigerant of the air conditioner is recovered.

[0006] In order to solve the above problems, the present invention provides a refrigerant recovery system, comprising: an indoor unit and an outdoor unit,

[0007] The outdoor unit includes a gas-liquid separator, a compressor, a four-way valve, and a heat exchanger connected in sequence;

[0008] The four-way valve includes a first outlet, a second outlet, a third outlet and a fourth outlet, the first outlet is connected to the outlet of the compressor through a fourth branch, the second outlet is connected to the inlet of the heat exchanger through a third branch, the third outlet is connected to the inlet of the gas-liquid separator through a sixth branch, the outlet of the gas-liquid separator is connected to the inlet of the compressor through a seventh branch, and the outlet of the heat exchanger and the fourth outlet are connected to the indoor unit;

[0009] The refrigerant recovery system also includes a second branch, one end of the second branch is connected to the sixth branch, the other end of the second branch is connected to the fourth branch, a second valve body is provided on the second branch, and a first valve body is provided on the third branch.

[0010] In some embodiments, the third branch is connected to the first branch, one end of the first branch is connected to the third branch, the other end of the first branch is connected to the sixth branch, one end of the first branch is located between the first valve body and the heat exchanger, the other end of the first branch is located between the third outlet and the second branch, and a third valve body is provided on the first branch.

[0011] In some embodiments, the refrigerant recovery system also includes an oil-gas separator, which has a first inlet, a second inlet and a fifth outlet, the first inlet is connected to the outlet of the compressor through a fifth branch, the second inlet is connected to the seventh branch through the fourth branch, the fifth outlet is connected to the fourth branch, a sixth valve body is provided on the fourth branch, and the sixth valve body is located between the fourth branch and the gas-liquid separator.

[0012] In some embodiments, a fourth valve body is provided on the sixth branch, and the fourth valve body is located between the second branch and the gas-liquid separator.

[0013] In some embodiments, the outlet of the heat exchanger is connected to the indoor unit through an eighth branch, the fourth outlet is connected to the indoor unit through a ninth branch, and a fifth valve body is provided on both the eighth branch and the ninth branch.

[0014] The present invention also provides an air conditioner, comprising the above-mentioned refrigerant recovery system.

[0015] The present invention also provides a control method for the above air conditioner, which comprises the following steps:

[0016] When the air conditioner needs to start the refrigerant recovery mode;

[0017] Determination step: determine whether the air conditioner is in cooling mode;

[0018] Control step: when the air conditioner is in cooling mode, control the air conditioner to start the refrigerant recovery mode; when the air conditioner is not in cooling mode, control the air conditioner to switch to cooling mode, and then control the air conditioner to start the refrigerant recovery mode.

[0019] In some implementations, controlling the air conditioner to start the refrigerant recovery mode further includes the following steps:

[0020] Judgment steps: determine whether there is a sensor failure in the air conditioner unit;

[0021] Control step: when there is no sensor failure in the air conditioner unit, control the air conditioner to start a normal refrigerant recovery mode; when there is a sensor failure in the air conditioner unit, control the air conditioner to start a sensor failure refrigerant recovery mode.

[0022] In some embodiments, when the third branch is connected to the first branch and a third valve body is provided on the first branch; controlling the air conditioner to start a normal refrigerant recovery mode includes the following steps: controlling the compressor to operate at a maximum frequency, controlling the second valve body to open, controlling the third valve body to open, and controlling the first valve body to close.

[0023] In some embodiments, controlling the compressor to operate at the maximum frequency is implemented according to the following steps: during the frequency increase or operation of the compressor, if the high pressure protection value Pb-the high pressure value Pd of the air conditioner unit ≤ 3°C, the compressor periodically reduces the frequency until the high pressure protection value Pb-the high pressure value Pd of the air conditioner unit is greater than 4°C; if the compressor has dropped to the minimum frequency and maintained for a first preset time, or the air conditioner unit protection occurs in the air conditioner, an instruction to stop refrigerant recovery is issued.

[0024] In some embodiments, when the third branch is connected to the first branch and a third valve body is provided on the first branch; controlling the air conditioner to start the sensor failure refrigerant recovery mode includes the following steps: controlling the air conditioner to shield the sensor failure, forcing the refrigerant recovery mode to run, the compressor to run at the lowest frequency, controlling the second valve body to open, controlling the third valve body to open, and controlling the first valve body to close.

[0025] In some embodiments, controlling the compressor to operate at the minimum frequency is implemented according to the following steps: after the compressor is started, it is first increased to medium frequency operation, and then operates at the minimum frequency. If the compressor operates at the minimum frequency and maintains it for a second preset time, or the air conditioner unit protection occurs in the air conditioner, an instruction to stop refrigerant recovery is issued.

[0026] The present invention provides a refrigerant recovery system, an air conditioner, and a control method thereof, which have the following beneficial effects:

[0027] A second valve body is provided on the second branch and a first valve body is provided on the third branch. When the air-conditioning unit needs to recover the refrigerant, the first valve body is closed and the second valve body is opened to allow the refrigerant discharged from the compressor to be recovered into the gas-liquid separator. Moreover, under the action of the compressor, the refrigerant in various parts of the air conditioner all flows into the gas-liquid separator, and most other positions of the outdoor unit are no longer troubled by being filled with refrigerant and unable to be replaced and repaired. Most of the refrigerant in the air conditioner is recovered, and the discharge of the refrigerant is greatly reduced. At the same time, the recovered refrigerant can be used again, which is environmentally friendly and energy-saving and reduces maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0029] Figure 1 is a structural schematic diagram of a refrigerant recovery system of the present invention;

[0030] Figure 2 is a refrigerant flow diagram of the refrigerant recovery system of the present invention in the refrigeration mode;

[0031] Figure 3 is a refrigerant flow diagram of the refrigerant recovery system of the present invention in the recovery mode;

[0032] Figure 4 is a flow chart of a method for controlling an air conditioner according to another embodiment of the present invention;

[0033] Figure 5 is a flow chart of a control method of an air conditioner in another embodiment of the present invention in the case of a sensor-free fault;

[0034] Figure 6 It is a flow chart of a method for controlling an air conditioner in another embodiment of the present invention in the case of a sensor failure.

[0035] The accompanying drawings are marked as follows:

[0036] 1. Compressor; 2. Heat exchanger; 3. Gas-liquid separator; 4. Oil-gas separator; 5. Four-way valve; 6. First valve body; 7. First branch; 8. Third valve body; 9. Third branch; 10. Fourth branch; 11. Fourth branch; 12. Fifth branch; 13. Throttle; 14. Second valve body; 15. Second branch; 16. Sixth branch; 17. Fourth valve body; 18. Seventh branch; 19. Eighth branch; 20. Ninth branch; 21. Fifth valve body; 22. Sixth valve body. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0039] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0040] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0041] See also Figure 1-6 As shown, according to an embodiment of the present invention, a refrigerant recovery system is provided, comprising: an indoor unit and an outdoor unit, the outdoor unit comprising a gas-liquid separator 3, a compressor 1, a four-way valve 5, and a heat exchanger 2 connected in sequence; the four-way valve 5 comprises a first outlet, a second outlet, a third outlet, and a fourth outlet, the first outlet is connected to the outlet of the compressor 1 through a fourth branch 10, the second outlet is connected to the inlet of the heat exchanger 2 through a third branch 9, the third outlet is connected to the inlet of the gas-liquid separator 3 through a sixth branch 16, the outlet of the gas-liquid separator 3 is connected to the inlet of the compressor 1 through a seventh branch 18, and the outlet of the heat exchanger 2 and the fourth outlet are connected to the indoor unit;

[0042] The refrigerant recovery system further includes a second branch 15, one end of which is connected to the sixth branch 16, and the other end of which is connected to the fourth branch 10. A second valve body 14 is provided on the second branch 15, and a first valve body 6 is provided on the third branch 9. In this technical solution, the second valve body 14 is provided on the second branch 15, and the first valve body 6 is provided on the third branch 9. When the air conditioner unit needs to recover the refrigerant, the first valve body 6 is closed and the second valve body 14 is opened, so that the refrigerant discharged by the compressor 1 is recovered into the gas-liquid separator 3. Moreover, under the action of the compressor 1, the refrigerant in each part of the air conditioner all flows into the gas-liquid separator 3, and most other positions of the outdoor unit are no longer faced with the problem of being filled with refrigerant and unable to be replaced and repaired. Most of the refrigerant in the air conditioner is recovered, which greatly reduces the discharge of refrigerant. At the same time, the recovered refrigerant can be reused, which is environmentally friendly and energy-saving, and reduces maintenance costs.

[0043] In some embodiments, the third branch 9 is connected to the first branch 7, one end of the first branch 7 is connected to the third branch 9, the other end of the first branch 7 is connected to the sixth branch 16, one end of the first branch 7 is located between the first valve body 6 and the heat exchanger 2, the other end of the first branch 7 is located between the third outlet and the second branch 15, and the first branch 7 is provided with a third valve body 8. In this technical solution, through the third valve body 8, if the air conditioner is in the heating and cooling mode before recovery, the third valve body 8 is opened to quickly and effectively recover a large amount of low-temperature refrigerant accumulated in the outdoor heat exchanger 2 to the gas-liquid separator 3, and if the air conditioner is in the cooling mode before recovery, it does not need to be opened.

[0044] In some embodiments, the refrigerant recovery system further includes an oil-gas separator 4, the oil-gas separator 4 having a first inlet, a second inlet and a fifth outlet, the first inlet being connected to the outlet of the compressor 1 through the fifth branch 12, the second inlet being connected to the seventh branch 18 through the fourth branch 11, the fifth outlet being connected to the fourth branch 10, the fourth branch 11 being provided with a sixth valve body 22, the sixth valve body 22 being located between the fourth branch 11 and the gas-liquid separator 3. In this technical solution, the sixth valve body 22 is used to facilitate control of the refrigerator to be fully recovered into the gas-liquid separator 3, effectively reducing the amount of refrigerant stored in the compressor. Compared with the traditional air-conditioning system, the refrigerant recovery system of the present invention adds the sixth valve body 22 and the third valve body 8, which can realize high-precision automatic recovery of refrigerant.

[0045] In some embodiments, a fourth valve body 17 is provided on the sixth branch 16, and the fourth valve body 17 is located between the second branch 15 and the gas-liquid separator 3. In this technical solution, the fourth valve body 17 is used to prevent the gaseous refrigerant in the gas-liquid separator 3 from flowing back into the unit after recovery, thereby improving the refrigerant recovery efficiency.

[0046] In some embodiments, the outlet of the heat exchanger 2 is connected to the indoor unit through an eighth branch 19, the fourth outlet is connected to the indoor unit through a ninth branch 20, and a fifth valve body 21 is provided on both the eighth branch 19 and the ninth branch 20. In this technical solution, further, a low-pressure sensor and a steam inlet pipe temperature-sensing package are provided on the sixth branch 16, and the low-pressure sensor and the steam inlet pipe temperature-sensing package are both located between the second branch 15 and the first branch 7, a steam outlet pipe temperature-sensing package is provided on the seventh branch 18, a high-pressure switch and an exhaust temperature-sensing package are provided on the fifth branch 12, a high-pressure temperature-sensing package is provided on the fourth branch 10, a defrost temperature-sensing package and a heating EEV are provided on the eighth branch 19, and the defrost temperature-sensing package and the heating EEV are sequentially arranged on the eighth branch 19 along the flow direction of the refrigerant in the eighth branch 19, a throttling device 13 is provided on the first branch 7 and the second branch 15, the throttling device 13 on the first branch 7 is located between the third valve body 8 and the heat exchanger 2, and the throttling device 13 on the second branch 15 is located between the second valve body 14 and the first outlet. Since the compressor 1 discharges high-temperature and high-pressure refrigerant, the throttling element 13 can effectively throttle and reduce the pressure of the refrigerant when the refrigerant is recovered, thereby improving the recovery efficiency.

[0047] The refrigerant recovery system of the present invention solves the problems that the existing refrigerant recovery needs manual operation, the recovered refrigerant is distributed in most of the pipelines inside the outdoor unit, the main components of the outdoor unit still have refrigerant after the recovery is completed, the automatic refrigerant recovery control is inaccurate, and the refrigerant cannot be recovered to the maximum extent. After the high-pressure sensor and the low-pressure sensor fail, the existing technology relies on high and low pressure judgment and cannot be recovered. The refrigerant recovery system of the present invention can recover the refrigerant to the maximum extent, and it will not have low recovery efficiency and low recovery volume like the existing technology. Recycling can still be carried out after a failure, which improves the applicable scenarios and brings greater convenience.

[0048] The refrigerant flow direction in the refrigerant recovery system of the present invention is:

[0049] In normal refrigeration mode: the compressor is working, the refrigerant is discharged from the exhaust port of the compressor 1 and flows into the oil-gas separator 4, and then flows into the outdoor heat exchanger 2 through the four-way valve 5 for condensation. At this time, the first valve body 6 is in an open state, and the condensed refrigerant passes through the heating EXV-outdoor unit liquid pipe to flow into the indoor unit liquid pipe and the indoor unit heat exchanger, and then flows out through the indoor unit gas pipe, and then flows into the outdoor unit gas pipe. The refrigerant flows into the four-way valve 5 through the outdoor unit gas pipe and then flows into the gas-liquid separator 3, and flows into the suction pipe of the compressor 1 through the outlet pipe of the gas-liquid separator 3, and then the compressor compresses again, and the cycle repeats.

[0050] Refrigerant recovery mode: After the recovery command is issued, the air conditioner first runs in cooling mode. After the refrigerant compressed by the compressor 1 flows out through the oil-gas separator 4, the first valve body 6 is closed and the second valve body 14 is opened. At this time, part of the refrigerant will flow into the gas-liquid separator 3 through the second valve body 14 that is immediately opened. The refrigerant flow is very small, and it is just a simple bypass. The first valve body 6 is closed to make the refrigerant only enter but not exit, leaving most of the refrigerant between the compressor 1 and the four-way valve 5, and then returning to the compressor 1 through the gas-liquid separator 3. Most of the refrigerant is blocked between the compressor 1 and the high-pressure recovery valve 6, and because the compressor continues to work, it provides "suction", and the refrigerant in the pipeline continues to flow into the gas-liquid separator 3 through the pipeline.

[0051] The present invention also provides an air conditioner, comprising the above-mentioned refrigerant recovery system.

[0052] The present invention also provides a control method for the above air conditioner, comprising the following steps:

[0053] When the air conditioner needs to start the refrigerant recovery mode;

[0054] Determination step: determine whether the air conditioner is in cooling mode;

[0055] Control step: when the air conditioner is in cooling mode, control the air conditioner to start the refrigerant recovery mode; when the air conditioner is not in cooling mode, control the air conditioner to switch to cooling mode, and then control the air conditioner to start the refrigerant recovery mode.

[0056] In some implementations, controlling the air conditioner to start the refrigerant recovery mode further includes the following steps:

[0057] Judgment steps: determine whether there is a sensor failure in the air conditioner unit;

[0058] Control step: when there is no sensor failure in the air conditioner unit, control the air conditioner to start a normal refrigerant recovery mode; when there is a sensor failure in the air conditioner unit, control the air conditioner to start a sensor failure refrigerant recovery mode.

[0059] The air conditioner unit is equipped with high-precision refrigerant recovery hardware and control. There are two ways to start refrigerant recovery. One is manual operation through the buttons on the outdoor unit main control panel. The relevant program is built into the outdoor unit main control panel. The other is to automatically start recovery after receiving the leakage signal from the refrigerant leakage detection sensor.

[0060] After receiving the command to start refrigerant recovery, the unit will first self-check. If the unit sensor is faulty and can participate in the judgment normally, the normal recovery mode will be started first. This mode has a fast recovery speed and accurate recovery. If the unit sensor is faulty, the recovery method in the fault mode will be started to shield the relevant fault signal and perform effective recovery.

[0061] In some embodiments, when the third branch 9 is connected to the first branch 7 and the first branch 7 is provided with a third valve body 8; controlling the air conditioner to start a normal refrigerant recovery mode includes the following steps: controlling the compressor 1 to operate at the maximum frequency, controlling the second valve body 14 to open, controlling the third valve body 8 to open, and controlling the first valve body 6 to close.

[0062] Normal refrigerant recovery control method

[0063] When the unit refrigerant is recovered, it must first be switched to the cooling mode. The recovery efficiency is high in the cooling mode. The four-way valve 5 in the cooling mode is in the power-off state. If the air conditioner is in the heating mode, the four-way valve 5 will automatically reset after the outdoor unit is powered off. A first valve body 6 is added to the connecting pipe between the outdoor heat exchanger 2 and the four-way valve 5. If it is recovered in the heating mode, the first valve body 6 cannot play a closing role. The four-way valve 5 is powered off, and then the compressor 1 starts to increase the frequency, and the target is raised to the highest. The higher the compressor frequency, the faster and better the recovery effect. After the frequency increase is completed, the first valve body 6 is closed to prevent the refrigerant from flowing out. At this time, in order to provide a certain pressure relief and improve the recovery effect, the second valve body 14 needs to be opened to allow part of the refrigerant to flow to the low-pressure side. If the unit is in heating operation before the refrigerant is recovered, the third valve body 8 needs to be opened as well. In order to quickly and effectively recover the large amount of low-temperature refrigerant accumulated in the outdoor heat exchanger 2 to the steam part, if it is cooling before recovery, the third valve body 8 does not need to be opened.

[0064] When the system refrigerant recovery is almost complete, the air conditioner unit has exhaust type and pressure abnormality protection, or it maintains the minimum frequency for a long time, about 3 minutes. At this time, the sixth valve body 22 of the gas-liquid separator 3 needs to be closed first, and the sixth valve body 22 is closed about 1 minute earlier than the seventh branch 17. The purpose is to recover the gas-liquid separator 3 to the greatest extent, reduce the proportion of the recovered refrigerant amount from the gas-liquid separator 3 to the compressor 1 side, and then close the seventh branch 17 to end the refrigerant recovery.

[0065] In some embodiments, controlling the compressor 1 to operate at the maximum frequency is implemented according to the following steps: during the frequency increase or operation of the compressor 1, if the high-pressure protection value Pb-the high-pressure value Pd of the air conditioner unit ≤3°C, the compressor 1 periodically reduces the frequency until the high-pressure protection value Pb-the high-pressure value Pd of the air conditioner unit>4°C; if the compressor 1 has dropped to the minimum frequency and maintained for a first preset time, or the air conditioner unit protection occurs in the air conditioner, an instruction to stop refrigerant recovery is issued.

[0066] The first preset time is 3 minutes. When the air conditioner is controlled to start the normal refrigerant recovery mode, the compressor 1 is controlled to run at the maximum frequency. During the frequency increase or operation of the compressor 1, if the high pressure value of the unit module rises to the vicinity of the protection value, that is, the high pressure protection value Pb-module high pressure value Pd≤3°C, the compressor will reduce the frequency by 3HZ speed at the common value of 10 seconds per cycle, and the common cycle value is 10 seconds, until the high pressure protection value Pb-module high pressure value Pd>4°C. If the compressor 1 has dropped to the minimum frequency and maintained for more than 3 minutes, or the unit protection occurs, a refrigerant recovery stop instruction is issued, and the relevant valves are linked. When the air conditioner starts the normal refrigerant recovery mode, the control of each valve body, the second valve body 14 is immediately opened until the recovery is completed and normal control is restored; before the third valve body 8 receives the recovery instruction, if the air conditioner unit is running in the refrigeration mode, it remains closed. If the unit is running in heating mode before recovery, it will be opened immediately and maintained until the sixth valve body 22 is closed 1 minute before closing. The third valve body 8 is normally closed during normal operation of the unit; the first valve body 6 is closed after the compressor 1 reaches the highest frequency, or the first valve body 6 is closed when the high-pressure frequency reduction is triggered during the frequency increase of the compressor 1. The first valve body 6 is normally open during normal operation; the fourth valve body 17 is closed immediately upon receiving the stop recovery instruction, or the compressor 1 drops to the minimum frequency and maintains for 3 minutes, or the unit has a protective shutdown. The fourth valve body 17 is normally open during normal operation; the sixth valve body 22 is immediately closed 1 minute before receiving the stop recovery instruction, or the compressor 1 drops to the minimum frequency and maintains for 2 minutes, or immediately closed when the unit has a protective shutdown. The sixth valve body 22 is normally open during normal operation; the four-way valve 5 is maintained or switched to the power-off state, that is, switched to the cooling mode.

[0067] In some embodiments, when the third branch 9 is connected to the first branch 7 and the first branch 7 is provided with a third valve body 8; controlling the air conditioner to start the sensor failure refrigerant recovery mode includes the following steps: controlling the air conditioner to shield the sensor failure, forcing the refrigerant recovery mode to run, the compressor 1 to run at the lowest frequency, controlling the second valve body 14 to open, controlling the third valve body 8 to open, and controlling the first valve body 6 to close.

[0068] The control method of refrigerant recovery mode in sensor failure mode is:

[0069] When the unit has an abnormal pressure sensor, it is impossible to control accurate recovery by judging the pressure parameters. At this time, it is necessary to control it by "time". Based on experience, it is determined how long it takes to set the recovery to basically complete the refrigerant recovery. Because pressure cannot be involved in the judgment, if the unit is operated at a high frequency, it may be damaged or malfunction, so the recovery operation frequency must be limited. It cannot be too high to cause the risk of damage to the unit, and it cannot be too low to cause poor recovery effect. Specifically, let compressor 1 run at a medium frequency for a period of time, and then run compressor 1 at a low frequency to take into account the recovery effect and the safety of the air conditioner unit. As the refrigerant decreases, the frequency needs to be reduced to ensure safe operation, and the control of the remaining valve bodies refers to the control in the normal operating mode.

[0070] In some embodiments, controlling the compressor 1 to operate at the minimum frequency is implemented according to the following steps: after the compressor 1 is started, it is first increased to medium frequency operation, and then operates at the minimum frequency. If the compressor 1 operates at the minimum frequency and maintains it for a second preset time, or the air conditioner unit protection occurs in the air conditioner, an instruction to stop refrigerant recovery is issued.

[0071] The second preset time is 15 minutes. When the air conditioner starts the refrigerant recovery mode with a sensor failure, the fault is shielded, forced to run, and compressor 1 is controlled to run at the lowest frequency. After compressor 1 is started, it first rises to the medium frequency and runs for 3 minutes, and then runs at the lowest frequency. The medium frequency is 50%*maximum frequency. If compressor 1 has reached the minimum frequency and maintains it for more than 15 minutes, or unit protection occurs, a command to stop refrigerant recovery is issued, and related valves are linked; when the air conditioner starts the refrigerant recovery mode with a sensor failure, the control of each valve body, the second valve body 14 is immediately opened until the recovery is completed and normal control is restored; before the third valve body 8 receives the recovery command, if the air conditioner unit is running in the refrigeration mode, it remains closed. If the unit is running in heating mode before recovery, it will be opened immediately and maintained until the sixth valve body 22 is closed 1 minute before closing. The third valve body 8 is normally closed during normal operation of the unit; the first valve body 6 is closed after the compressor 1 reaches the highest frequency, or the first valve body 6 is closed when the high-pressure frequency reduction is triggered during the frequency increase of the compressor 1. The first valve body 6 is normally open during normal operation; the fourth valve body 17 is closed immediately upon receiving the stop recovery instruction, or the compressor 1 drops to the minimum frequency and maintains for 3 minutes, or the unit has a protective shutdown. The fourth valve body 17 is normally open during normal operation; the sixth valve body 22 is immediately closed 1 minute before receiving the stop recovery instruction, or the compressor 1 drops to the minimum frequency and maintains for 2 minutes, or immediately closed when the unit has a protective shutdown. The sixth valve body 22 is normally open during normal operation; the four-way valve 5 is maintained or switched to the power-off state, that is, switched to the cooling mode.

[0072] The control method of the air conditioner of the present invention can improve the rationality and accuracy of recovery. Two recovery modes are designed. In addition to the traditional judgment based on parameters, a refrigerant recovery method under fault mode is also designed to improve the applicability of scenarios.

[0073] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A refrigerant recovery system, characterized in that: include: Indoor and outdoor units, The outdoor unit comprises a gas-liquid separator (3), a compressor (1), a four-way valve (5), and a heat exchanger (2) which are connected in sequence; The four-way valve (5) comprises a first outlet, a second outlet, a third outlet and a fourth outlet, the first outlet being connected to the outlet of the compressor (1) via a fourth branch (10), the second outlet being connected to the inlet of the heat exchanger (2) via a third branch (9), the third outlet being connected to the inlet of the gas-liquid separator (3) via a sixth branch (16), the outlet of the gas-liquid separator (3) being connected to the inlet of the compressor (1) via a seventh branch (18), and the outlet of the heat exchanger (2) and the fourth outlet being connected to the indoor unit; The refrigerant recovery system further comprises a second branch (15), one end of the second branch (15) being connected to the sixth branch (16), the other end of the second branch (15) being connected to the fourth branch (10), a second valve body (14) being provided on the second branch (15), and a first valve body (6) being provided on the third branch (9).

2. The refrigerant recovery system according to claim 1, characterized in that: The third branch (9) is connected to the first branch (7), one end of the first branch (7) is connected to the third branch (9), the other end of the first branch (7) is connected to the sixth branch (16), one end of the first branch (7) is located between the first valve body (6) and the heat exchanger (2), the other end of the first branch (7) is located between the third outlet and the second branch (15), and a third valve body (8) is provided on the first branch (7).

3. The refrigerant recovery system according to claim 1, characterized in that: The refrigerant recovery system also includes an oil-gas separator (4), the oil-gas separator (4) having a first inlet, a second inlet and a fifth outlet, the first inlet being connected to the outlet of the compressor (1) via a fifth branch (12), the second inlet being connected to the seventh branch (18) via the fourth branch (11), the fifth outlet being connected to the fourth branch (10), a sixth valve body (22) being provided on the fourth branch (11), the sixth valve body (22) being located between the fourth branch (11) and the gas-liquid separator (3).

4. The refrigerant recovery system according to claim 1, characterized in that: A fourth valve body (17) is provided on the sixth branch (16), and the fourth valve body (17) is located between the second branch (15) and the gas-liquid separator (3).

5. The refrigerant recovery system according to claim 1, characterized in that: The outlet of the heat exchanger (2) is connected to the indoor unit via an eighth branch (19), the fourth outlet is connected to the indoor unit via a ninth branch (20), and a fifth valve body (21) is provided on both the eighth branch (19) and the ninth branch (20).

6. An air conditioner, characterized in that: A refrigerant recovery system comprising the refrigerant recovery system according to any one of claims 1 to 5.

7. The air conditioner control method according to claim 6, characterized in that: The following steps are involved: When the air conditioner needs to start the refrigerant recovery mode; Determination step: determine whether the air conditioner is in cooling mode; Controlling step: when the air conditioner is in cooling mode, controlling the air conditioner to start a refrigerant recovery mode; When the air conditioner is not in cooling mode, the air conditioner is controlled to switch to cooling mode, and then the air conditioner is controlled to start a refrigerant recovery mode.

8. The control method of the air conditioner according to claim 7, characterized in that: Controlling the air conditioner to start the refrigerant recovery mode also includes the following steps: Judgment steps: determine whether there is a sensor failure in the air conditioner unit; Control step: when there is no sensor failure in the air conditioner unit, control the air conditioner to start a normal refrigerant recovery mode; when there is a sensor failure in the air conditioner unit, control the air conditioner to start a sensor failure refrigerant recovery mode.

9. The air conditioner control method according to claim 8, characterized in that: When the third branch (9) is connected to the first branch (7) and the first branch (7) is provided with a third valve body (8); controlling the air conditioner to start a normal refrigerant recovery mode comprises the following steps: controlling the compressor (1) to operate at a maximum frequency, controlling the second valve body (14) to open, controlling the third valve body (8) to open, and controlling the first valve body (6) to close.

10. The air conditioner control method according to claim 9, characterized in that: Controlling the compressor (1) to operate at the maximum frequency is implemented according to the following steps: during the frequency increase or operation of the compressor (1), if the high-pressure protection value Pb-the high-pressure value Pd of the air conditioner unit ≤ 3°C, the compressor (1) periodically reduces the frequency until the high-pressure protection value Pb-the high-pressure value Pd of the air conditioner unit> 4°C; if the compressor (1) has dropped to the minimum frequency and maintained for a first preset time, or the air conditioner unit protection occurs in the air conditioner, a command to stop refrigerant recovery is issued.

11. The air conditioner control method according to claim 8, characterized in that: When the third branch (9) is connected to the first branch (7) and the first branch (7) is provided with a third valve body (8); controlling the air conditioner to start the sensor failure refrigerant recovery mode includes the following steps: controlling the air conditioner to shield the sensor failure, forcing the refrigerant recovery mode to run, the compressor (1) to run at the lowest frequency, controlling the second valve body (14) to open, controlling the third valve body (8) to open, and controlling the first valve body (6) to close.

12. The air conditioner control method according to claim 11, characterized in that: Controlling the compressor (1) to operate at the minimum frequency is implemented according to the following steps: after the compressor (1) is started, it is first increased to medium frequency operation, and then operates at the minimum frequency. If the compressor (1) operates at the minimum frequency and maintains it for a second preset time, or the air conditioner unit protection occurs in the air conditioner, an instruction to stop refrigerant recovery is issued.

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