Refrigerant recovery system for testing a refrigeration device and control method thereof

Abstract

The application provides a refrigerant recovery system for refrigeration equipment test and a control method thereof, which comprises a compressor A, a three-way valve, a condenser, an oil separator A, a first pipeline, a second pipeline and a third pipeline, the three-way valve comprises a C port, a D port and an E port, one end of the first pipeline is communicated with the C port, and the other end can be communicated with a discharge end of the compressor A, one end of the second pipeline is communicated with the D port, and the other end is communicated with the oil separator A, one end of the third pipeline is communicated with the E port, and the other end can be communicated with the condenser, when the compressor A is started, the C port can be connected with the D port, and the E port is closed; when the compressor A is closed, the E port can be connected with the D port, and the C port is closed. According to the application, the problem that the flow direction of refrigerant in the oil separator is inconsistent when the refrigeration equipment is normally operated and when the recovery system is operated can be solved, and the problem that the efficiency of the oil separator is not high when the recovery system of the prior art is operated can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of refrigeration technology, in particular to a refrigerant recovery system for refrigeration equipment testing and a control method thereof. BACKGROUND

[0002] The emission of freon gas can destroy the atmosphere, cause the greenhouse effect and lead to a series of environmental problems such as global warming. Refrigeration equipment using freon refrigerant is applied in various industries, from source production detection to user use, after-sales maintenance and scrap processing, etc. Freon refrigerant leakage may exist in each process link, and even there may be human private discharge. With the increasingly strict supervision of freon refrigerant, it is necessary to strictly monitor, recycle and regenerate the freon refrigerant in each process link, especially in the testing and maintenance process, the refrigerant in the refrigeration equipment often needs to be moved to ensure that the refrigerant does not leak into the atmosphere environment when the connecting pipe is disconnected.

[0003] After-sales maintenance is difficult to supervise, and it is rare to use refrigerant recovery equipment for after-sales maintenance, especially for after-sales maintenance of household air conditioners. There are a lot of refrigerant leakage and collection of snow species fees. On the other hand, the compressors of some special air conditioners, especially the indoor units of computer room air conditioners, are placed in the low-pressure indoor unit. The pressure test leakage refrigerant in the production test process is different from the rated filling refrigerant of the unit. It is difficult to accurately control the refrigerant filling amount in the unit at the time of delivery during the frequent connection test process. Basically, only the refrigerant can be refilled after vacuumizing, which is very wasteful of refrigerant and causes high production cost; vacuumizing, pressure testing and refilling refrigerant are also very wasteful of production time and cause low production efficiency.

[0004] It is necessary to develop a refrigerant recovery adjustment device for accurately transferring the original refrigerant in the refrigeration equipment during production, detection and after-sales maintenance to ensure that it is not wasted or leaked. Related application patent CN202110944696.3 optimizes the design and research in this regard, but the recovery system involved in the patent runs, the low-pressure refrigerant suction of the recovery compressor passes through the first oil separator, and the refrigerant flow direction is opposite to that of the conventional oil separator. It cannot achieve high-efficiency oil separation effect, and the lubricating oil remaining in the refrigeration equipment in the outdoor unit is more likely to enter the recovery compressor, causing lubricating oil mixing and affecting the lubricating oil amount of the recovery compressor.

[0005] Because the refrigeration equipment in the prior art has the technical problem that the refrigerant flow direction in the oil separator is inconsistent between normal operation and recovery system operation, which cannot achieve oil separation function or has low oil separation effect, the present application researches and designs a refrigerant recovery system for refrigeration equipment testing and a control method thereof. SUMMARY

[0006] Therefore, the technical problem to be solved by the present application is to overcome the defect that the flow direction of refrigerant in the oil separator is inconsistent between normal operation and recovery system operation in the prior art, so as to provide a refrigerant recovery system for refrigeration equipment test and a control method thereof.

[0007] To solve the above problems, the present application provides a refrigerant recovery system for refrigeration equipment test, comprising:

[0008] The compressor A, the three-way valve, the condenser, the oil separator A, the first pipeline, the second pipeline and the third pipeline, the three-way valve comprises a C port, a D port and an E port, one end of the first pipeline is in communication with the C port, and the other end can be in communication with the exhaust end of the compressor A, one end of the second pipeline is in communication with the D port, and the other end is in communication with the oil separator A, one end of the third pipeline is in communication with the E port, and the other end can be in communication with the condenser, when the compressor A is started, a refrigeration equipment test mode is run, at this time the C port can be connected with the D port, and the E port is closed, so as to realize oil-gas separation by entering the oil separator A through the second pipeline via the D port; when the compressor A is closed, a recovery system recovery mode is run, at this time the E port can be connected with the D port, and the C port is closed, so as to realize oil-gas separation by entering the oil separator A through the second pipeline via the E port.

[0009] In some embodiments, when the compressor A is started, the mixture of refrigerant and lubricating oil discharged from the exhaust end of the compressor A enters the oil separator A through the first pipeline, the C port, the D port and the second pipeline for oil-gas separation; when the compressor A is closed, the mixture of refrigerant and lubricating oil in the condenser enters the oil separator A through the third pipeline, the E port, the D port and the second pipeline for oil-gas separation.

[0010] In some embodiments, it further comprises a fourth pipeline and a one-way valve D, one end of the fourth pipeline is connected to the upper part of the inside of the oil separator A, and the other end is in communication with the third pipeline, the one-way valve D is arranged on the fourth pipeline to allow fluid to flow only from the oil separator A to the third pipeline.

[0011] In some embodiments, it further comprises an evaporator, an expansion valve, a fifth pipeline, a sixth pipeline and a seventh pipeline, one end of the fifth pipeline can be in communication with the condenser, and the other end can be in communication with the expansion valve, one end of the sixth pipeline is in communication with the expansion valve, and the other end is in communication with the evaporator, one end of the seventh pipeline is in communication with the inner bottom part of the oil separator A, and the other end is in communication with the fifth pipeline.

[0012] In some embodiments, the seventh pipeline is provided with a first throttling device and a one-way valve A, which can only allow fluid to flow from the oil separator A to the fifth pipeline.

[0013] In some embodiments, further comprising a compressor B, an oil separator B, a second throttling device, an eighth pipeline, a ninth pipeline and a tenth pipeline, one end of the eighth pipeline is in communication with the fourth pipeline, and the other end is in communication with the air inlet end of the compressor B, one end of the ninth pipeline is in communication with the air outlet end of the compressor B, and the other end is in communication with the inside of the oil separator B, one end of the tenth pipeline is in communication with the inner bottom of the oil separator B, and the other end is in communication with the eighth pipeline, and the second throttling device is arranged on the tenth pipeline.

[0014] In some embodiments, further comprising an eleventh pipeline and a one-way valve B, one end of the eleventh pipeline is in communication with the air outlet of the oil separator B, and the other end is in communication with the fifth pipeline, and the one-way valve B is arranged on the eleventh pipeline to only allow fluid to flow from the oil separator B to the fifth pipeline.

[0015] In some embodiments, the fourth pipeline and the eighth pipeline meet at a first meeting position, and the tenth pipeline is also connected at the first meeting position;

[0016] The seventh pipeline and the fifth pipeline meet at a second meeting position, and the eleventh pipeline is also connected at the second meeting position;

[0017] A one-way valve C is arranged on the fifth pipeline between the condenser and the second meeting position, which can only allow fluid to flow from the condenser to the second meeting position.

[0018] In some embodiments, the first pipeline is further provided with a gas valve, an interface A and an interface C, the fifth pipeline is provided with a liquid valve, an interface B and an interface D between the second meeting position and the expansion valve, the third pipeline is provided with an interface E, and the fifth pipeline is provided with an interface F between the second meeting position and the condenser, and a fluorine injection nozzle is arranged between the evaporator and the compressor A.

[0019] In some embodiments, the three-way valve is a differential pressure three-way valve, which comprises a valve body, a piston and an elastic member, and an inner cavity is arranged in the valve body; the D port, the C port and the E port are respectively in communication with the inner cavity, the D port is arranged on one side of the valve body, and the C port and the E port are respectively arranged on the other side of the valve body.

[0020] The piston and the elastic member are arranged in the inner cavity; one end of the elastic member is connected to the end of the valve body away from the C port, and the other end is connected to the piston;

[0021] The piston has a first position in which the C port and the D port are connected and the E port is completely sealed, and a second position in which the E port and the D port are connected and the C port is not completely sealed.

[0022] In some embodiments, one end of the inner cavity is provided with a first end cover, and the other end is provided with a second end cover; one end of the elastic member is connected to the second end cover; one end of the piston away from the elastic member is connected to a first positioning column, and the other end of the piston connected to the elastic member is connected to a second positioning column, and the length of the first positioning column is greater than the minimum distance between the C port and the first end cover, and the length of the second positioning column is less than the minimum distance between the E port and the second end cover.

[0023] The application also provides a control method of the refrigerant recovery system for testing refrigeration equipment, wherein when the refrigerant recovery system for testing refrigeration equipment simultaneously comprises a compressor A and a compressor B, the control method comprises:

[0024] a judging step of judging whether the required operation mode of the refrigerant recovery system is a refrigeration equipment testing mode or a recovery system recovery mode;

[0025] a control step of controlling the compressor A to be opened and the compressor B to be closed when the required operation mode of the refrigerant recovery system needs to be operated in the refrigeration equipment testing mode, and controlling the compressor A to be closed and the compressor B to be opened when the required operation mode of the refrigerant recovery system needs to be operated in the recovery system recovery mode.

[0026] The refrigerant recovery system for testing refrigeration equipment and the control method thereof provided by the application have the following advantages

[0027] Advantages:

[0028] The application sets the three-way valve, the oil separator A, the compressor A and the condenser, so that the three ports of the three-way valve are communicated to the compressor A, the oil separator A and the condenser respectively, the pressure of the C port of the three-way valve is high in the refrigeration equipment test mode, the C port and the D port are automatically switched to be communicated, the E port is closed, at this time, the mixture of the refrigerant and the oil discharged by the compressor A enters the oil separator A through the second pipeline to carry out the oil-gas separation, and in the recovery system recovery mode, the pressure of the C port is small by closing the compressor A, the E port and the D port are automatically switched to be communicated by the three-way valve, so that the mixture of the refrigerant and the oil in the condenser part enters the separator A through the third pipeline, the E port, the D port and the second pipeline to carry out the oil-gas separation, so that the different test modes and the recovery modes are effectively separated by the second pipeline to enter the oil separator A to carry out the oil-gas separation, the refrigerant flow directions in the oil separator are consistent when the refrigeration equipment is normally operated and when the recovery system is operated, and the oil-gas separation can be effectively carried out, the problem that the refrigerant flow directions in the oil separator are inconsistent when the refrigeration equipment is normally operated and when the recovery system is operated is solved, and the problem that the efficiency of the oil separator is not high when the recovery system of the prior art is operated is solved, the refrigerant recovery problem after the online test is ended, the refrigeration equipment and the recovery system are mixed with the refrigeration oil, and the like can be solved by the operation control of the recovery compressor B through the opening and closing combination of different valves when the above-mentioned recovery system is connected with the refrigeration equipment. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is the structure diagram of the refrigeration equipment test refrigerant recovery system of the application;

[0030] Figure 2 is the structure diagram of the ED conduction mode of the differential pressure three-way valve of the application;

[0031] Figure 3 is the structure diagram of the CD conduction mode of the differential pressure three-way valve of the application.

[0032] The signs are represented as:

[0033] 1. Compressor A; 2. Three-way valve; C, C port; D, D port; E, E port; 21. Valve body; 22. Piston; 23. Elastic member; 24. First end cover; 25. Second end cover; 26. First positioning post; 27. Second positioning post; 3. Condenser; 4. Evaporator; 5. Expansion valve; 6. Oil separator A; 71. Check valve A; 72. Check valve B; 73. Check valve C; 74. Check valve D; 81. First throttling device; 82. Second throttling device; 9. Compressor B; 10. Oil separator B; 11. First connection position; 12. Second Two-phase connection position; 13, gas valve; 141, interface A; 142, interface B; 143, interface C; 144, interface D; 145, interface E; 146, interface F; 15, liquid valve; 16, fluorine injection nozzle; 171, gas fluorine pipe; 172, liquid fluorine pipe; 101, first pipeline; 102, second pipeline; 103, third pipeline; 104, fourth pipeline; 105, fifth pipeline; 106, sixth pipeline; 107, seventh pipeline; 108, eighth pipeline; 109, ninth pipeline; 110, tenth pipeline; 111, eleventh pipeline. DETAILED DESCRIPTION

[0034] like Figures 1-3 As shown, the present invention provides a refrigerant recovery system for refrigeration equipment testing, which includes:

[0035] Compressor A1, three-way valve 2, condenser 3, oil separator A6, first pipeline 101, second pipeline 102 and third pipeline 103, the three-way valve 2 includes C port C, D port D and E port E, one end of the first pipeline 101 is connected to the C port C, and the other end can be connected to the exhaust end of the compressor A1 (such as Figure 1 As shown, the first pipeline 101 is preferably connected to the exhaust end of the compressor A1 through the gas fluorine pipe 171), one end of the second pipeline 102 is connected to the D port D, and the other end is connected to the oil separator A6, one end of the third pipeline 103 is connected to the E port E, and the other end can be connected to the condenser 3. When the compressor A1 is started, the refrigeration equipment test mode is operated. At this time, the C port C can be connected to the D port D, and the E port E is closed, so that the oil enters the oil separator A6 through the second pipeline 102 through the D port D to achieve oil and gas separation; when the compressor A1 is shut down, the recovery system recovery mode is operated. At this time, the E port E can be connected to the D port D, and the C port C is closed, so that the oil enters the oil separator A6 through the second pipeline 102 through the E port E to achieve oil and gas separation.

[0036] The application sets the three-way valve, the oil separator A, the compressor A and the condenser, so that the three ports of the three-way valve are communicated to the compressor A, the oil separator A and the condenser respectively, the pressure of the C port of the three-way valve is high in the refrigeration equipment test mode, the C port and the D port are automatically communicated and the E port is closed, so that the mixture of the refrigerant and the oil discharged by the compressor A enters the oil separator A through the second pipeline to carry out oil-gas separation, and the pressure of the C port is small in the recovery system recovery mode by stopping the compressor A, the E port and the D port are automatically communicated by the three-way valve, so that the mixture of the refrigerant and the oil in the condenser part enters the separator A through the third pipeline, the E port, the D port and the second pipeline to carry out oil-gas separation, so that the different test modes and the recovery modes can enter the oil separator A through the second pipeline to carry out oil-gas separation, the refrigerant flow directions in the oil separator are consistent in the normal operation of the refrigeration equipment and the operation of the recovery system, and the oil-gas separation can be effectively carried out, the problem that the refrigerant flow directions in the oil separator are inconsistent in the normal operation of the refrigeration equipment and the operation of the recovery system is solved, and the problem that the oil separator efficiency is not high in the operation of the recovery system in the prior art is solved; when the above recovery system is connected with the refrigeration equipment, the refrigerant recovery problem after the online test is ended, the frozen oil mixing problem of the refrigeration equipment and the recovery system and the like can be solved by the operation control of the recovery compressor B through different valve opening and closing combinations.

[0037] The application solves the above technical problems by adopting a special recovery system, connecting the oil return pipeline at the inlet and outlet of the refrigerant recovery system to recover the frozen oil separated from the refrigeration equipment in advance, connecting the oil return branch at the high and low pressure ports of the recovery compressor of the refrigerant recovery system to realize the frozen oil recovery of the recovery system itself, combining the differential pressure three-way valve and the check valve to keep the refrigerant flow directions in the oil separator consistent in the operation of the refrigeration equipment and the operation of the recovery system, solve the problem that the oil separator efficiency is not high in the operation of the recovery system in the prior art, and the refrigerant recovery problem after the online test is ended, the frozen oil mixing problem of the refrigeration equipment and the recovery system and the like can be solved by the operation control of the recovery compressor B through different valve opening and closing combinations when the above recovery system is connected with the refrigeration equipment.

[0038] The application guarantees that the refrigerant flow directions in the oil separator are consistent in the operation of the refrigeration equipment and the operation of the recovery system by the combination design of the check valve D and the differential pressure three-way valve, so that the oil separator can realize high-efficiency separation of the lubricating oil in the two cases (1. compression refrigeration, that is, the normal test mode; 2. the compressor stops, that is, the test is ended, the recovery mode is operated).

[0039] The application solves the following technical problems:

[0040] 1. The flow direction of refrigerant in the oil separator is inconsistent between normal operation and recovery system operation. (Because the outlet pipe cannot ensure centrifugal rotation of refrigerant inside the oil separator when entering the oil separator in reverse, there is no centrifugal motion to achieve centrifugal separation.)

[0041] 2. Control switching problem before the recovery system starts at the end of the test, and control method problem of the recovery system, etc.

[0042] In some embodiments, when the compressor A1 is started, the mixture of refrigerant and lubricating oil discharged from the discharge end of the compressor A1 enters the oil separator A6 through the first pipeline 101, the C port C, the D port D, and the second pipeline 102 for oil-gas separation; when the compressor A1 is turned off, the mixture of refrigerant and lubricating oil in the condenser 3 enters the oil separator A6 through the third pipeline 103, the E port E, the D port D, and the second pipeline 102 for oil-gas separation. This is a further preferred structure of the present application, that is, when the compressor A is started, the refrigerant and oil enter the oil separator A through the C port and the D port for oil-gas separation, and the separated gas enters the condenser through the third pipeline; when the compressor A is turned off, the flow direction of the refrigerant in the third pipeline is reversed, and the refrigerant enters the oil separator A through the third pipeline, the E port, and the D port for oil-gas separation, but the flow direction into the oil separator A is the same, both entering the oil separator A through the second pipeline, thus effectively ensuring that the flow direction of the fluid flowing into the oil separator A is consistent in the two different modes, effectively ensuring the normal and efficient oil-gas separation of the oil separator A.

[0043] In some embodiments, a fourth pipeline 104 and a one-way valve D74 are further included, one end of the fourth pipeline 104 is connected to the upper part inside the oil separator A6, the other end is in communication with the third pipeline 103, and the one-way valve D74 is arranged on the fourth pipeline 104 to allow fluid to flow only from the oil separator A6 to the third pipeline 103. The present application can effectively guide the gas exhaust separated by the oil separator A when the compressor A is started to the third pipeline through the fourth pipeline and the one-way valve D, and the one-way valve D is arranged to prevent the refrigerant and oil returned by the condenser through the third pipeline from returning to the compressor B through the fourth pipeline when the compressor A is turned off. (Prevent the fourth pipeline 104 from bypassing the oil separator A, at this time the oil separator A and the fourth pipeline 104 form a parallel connection, so only a small amount of fluid passes through the oil separator A), preventing the oil separator A from failing to normally oil-gas separate due to the small flow rate.

[0044] The oil return pipeline (including the second pipeline 102, the fourth pipeline 104 and the seventh pipeline 107) comprises three pipeline ports, which are respectively an air inlet of the oil separator A6 (i.e. the interface D of the three-way valve 2 connected with the second pipeline 102), an air outlet of the oil separator A6 (i.e. the eighth pipeline 108 connected with the fourth pipeline 104 (i.e. the first connection position 11)) and an oil return port of the oil return pipeline (i.e. the interface of the seventh pipeline 107 and the fifth pipeline 105 (i.e. the second connection position 12)), and the oil return port is connected with the oil outlet of the oil separator A6 through a capillary tube A (the first throttling device 81) and a one-way valve A71, and the arrangement direction of the one-way valve A71 is from the oil outlet of the oil separator to the oil return port. The air inlet of the oil separator A6 is connected with the D port of the differential pressure three-way valve; the air outlet of the oil separator A6 is connected between the interface E145 and the differential pressure three-way valve through the one-way valve D74, and the arrangement direction of the one-way valve D74 is from the air outlet of the oil separator A6 to the interface E145; and the oil return port of the oil return pipeline is connected between the interface D144 and the one-way valve C73.

[0045] In some embodiments, the evaporator 4, the expansion valve 5, the fifth pipeline 105, the sixth pipeline 106 and the seventh pipeline 107 are further included, one end of the fifth pipeline 105 is in communication with the condenser 3 and the other end is in communication with the expansion valve 5 (as shown in the figure, the fifth pipeline 105 is in communication with the expansion valve 5 through the liquid fluorine tube 172), one end of the sixth pipeline 106 is in communication with the expansion valve 5 and the other end is in communication with the evaporator 4, and one end of the seventh pipeline 107 is in communication with the inner bottom of the oil separator A6 and the other end is in communication with the fifth pipeline 105. Figure 1 The present application can effectively form a refrigeration cycle loop of the evaporator and the expansion valve with the condenser and the compressor A through the fifth and sixth pipelines, and the seventh pipeline is used for guiding the oil separated from the bottom of the oil separator A to the fifth pipeline and returning to the compressor A, so that the oil recovery is realized.

[0046] In some embodiments, the first throttling device 81 and the one-way valve A71 are arranged on the seventh pipeline 107, and the one-way valve A71 can only allow the fluid to flow from the oil separator A6 to the fifth pipeline 105. The first throttling device arranged on the seventh pipeline can throttle and reduce the pressure of the high-pressure oil, so as to ensure that the lubricating oil continuously passes and prevent a large amount of refrigerant gas from passing, and the one-way valve A can avoid the situation that the refrigerant and the oil of the fifth pipeline and the like return to the oil separator A.

[0047] In some embodiments, the compressor B9, the oil separator B10, the second throttling device 82, the eighth pipeline 108, the ninth pipeline 109 and the tenth pipeline 110 are further included, one end of the eighth pipeline 108 is communicated with the fourth pipeline 104, the other end is communicated with the gas inlet end of the compressor B9, one end of the ninth pipeline 109 is communicated with the gas outlet end of the compressor B9, the other end is communicated to the upper part of the inside of the oil separator B10, one end of the tenth pipeline 110 is communicated with the inner bottom of the oil separator B10, the other end is communicated to the eighth pipeline 108, and the second throttling device 82 is arranged on the tenth pipeline 110. The compressor B provided by the application can provide power for the recovery mode, the oil and gas mixture at the gas outlet end of the compressor B is separated by the oil separator B, the separated oil in the oil separator B is guided to the inlet end of the compressor B through the tenth pipeline, so that the internal components of the compressor B are continuously lubricated and cooled.

[0048] The compression pipeline comprises the compressor B, the oil separator B and the one-way valve B connected in sequence, the inlet of the compression pipeline, i.e. the suction port of the compressor B, is connected to the pipeline between the gas outlet of the oil separator A and the inlet of the one-way valve D, the oil outlet of the oil separator B is connected to the pipeline between the compressor B and the gas outlet of the oil separator A through the capillary B, and the outlet of the compression pipeline, i.e. the outlet of the one-way valve B, is connected to the pipeline between the interface D and the one-way valve C.

[0049] As shown in Figure 1 The indoor unit at least comprises the compressor A, the evaporator, the expansion valve, the gas valve and the liquid valve, the gas valve is connected with the interface A (the gas outlet), and the liquid valve is connected with the interface B (the liquid inlet). The gas valve and the liquid valve are usually provided with the fluorine injection nozzle, and the gas valve and the liquid valve can be manually opened or closed. When the gas valve and / or the liquid valve are closed, the fluorine injection nozzle on the gas valve or the liquid valve can only be communicated with the outdoor unit or the indoor unit. The application defaults that when the gas valve or the liquid valve is closed, the fluorine injection nozzle on the gas valve or the liquid valve is communicated with the outdoor unit, and is not communicated with the indoor unit. The outdoor unit at least comprises the condenser, the gas inlet and the liquid outlet.

[0050] In some embodiments, a eleventh pipeline 111 and a one-way valve B72 are further included, one end of the eleventh pipeline 111 is communicated with the gas outlet of the oil separator B10, the other end is communicated to the fifth pipeline 105, the one-way valve B72 is arranged on the eleventh pipeline 111 to allow fluid to flow only from the oil separator B10 to the fifth pipeline 105. The present application can also guide the refrigerant gas separated by the oil separator B to the fifth pipeline through the arrangement of the eleventh pipeline and the one-way valve B, so as to return to the compressor A, and the one-way valve B is used to prevent the backflow of refrigerant and oil from the fifth pipeline and the like into the oil separator B.

[0051] In some embodiments, the fourth pipeline 104 and the eighth pipeline 108 meet at a first meeting position 11, and the tenth pipeline 110 is also connected to the first meeting position 11.

[0052] The seventh pipeline 107 and the fifth pipeline 105 meet at a second meeting position 12, and the eleventh pipeline 111 is also connected to the second meeting position 12.

[0053] A one-way valve C73 is arranged on the fifth pipeline 105 between the condenser 3 and the second meeting position 12, and the one-way valve C73 can only allow fluid to flow from the condenser 3 to the second meeting position 12.

[0054] This is a further preferred structure of the present application, that is, the fourth pipeline, the eighth pipeline and the tenth pipeline are commonly connected to the first meeting position, and the fifth pipeline, the seventh pipeline and the eleventh pipeline commonly meet at the second meeting position, so as to realize compact structure and ensure normal operation of oil and refrigerant recovery.

[0055] Further preferably, the first throttling device is a capillary tube A, and the second throttling device is a capillary tube B.

[0056] In some embodiments, a gas valve 13, an interface A 141 and an interface C 143 are further arranged on the first pipeline 101, a liquid valve 15, an interface B 142 and an interface D 144 are arranged on the fifth pipeline 105 between the second meeting position 12 and the expansion valve 5, an interface E 145 is arranged on the third pipeline 103, an interface F 146 is arranged on the fifth pipeline 105 between the second meeting position 12 and the condenser 3, and a fluorine injection nozzle 16 is arranged between the evaporator 4 and the compressor A1. The present application can also effectively connect the indoor unit, the recovery system and the outdoor unit as an integrated structure through the arrangement of multiple valves and interfaces, and control the corresponding valves and interfaces to be opened or closed according to needs, so as to ensure normal and reliable operation of the refrigeration equipment in test mode and recovery mode.

[0057] As shown in Figure 1 The recovery system has four interfaces C / D / E / F, the interface C is connected with the interface A of the indoor unit through the gas fluorine pipe, the interface D is connected with the interface B of the indoor unit through the liquid fluorine pipe, the interfaces E / F are connected with the inlet and outlet of the outdoor unit respectively; the gas valve is arranged on the exhaust pipe of the indoor unit, and the liquid valve is arranged on the liquid return pipe of the indoor unit. The differential pressure type three-way valve is arranged on the suction pipe between the interface C and the interface E, the interface C is connected with the C port, the interface E is connected with the E port, and the D port of the differential pressure type three-way valve is connected with the gas inlet of the oil separator A; the one-way valve C is arranged on the exhaust pipe between the interface D and the interface F, and the arrangement direction is from the interface F to the interface D.

[0058] In some embodiments, the three-way valve 2 is a differential pressure type three-way valve, which comprises a valve body 21, a piston 22 and an elastic member 23, and the valve body 21 is internally provided with an inner cavity; the D port D, the C port C and the E port E are respectively communicated with the inner cavity, the D port D is arranged on one side of the valve body 21, and the C port C and the E port E are respectively arranged on the other side of the valve body 21.

[0059] The piston 22 and the elastic member 23 are both arranged in the inner cavity; one end of the elastic member 23 is connected with the end of the valve body 21 away from the C port C, and the other end is connected with the piston 22.

[0060] The piston 22 has a first position capable of connecting the C port C with the D port D and completely sealing the E port E, and a second position capable of connecting the E port E with the D port D and not completely sealing the C port C.

[0061] This is the preferred structure of the three-way valve of the present application, which does not need external power source, can utilize the pressure change of the pipeline itself and the elastic member force as the driving source to complete the switching action of the three-way valve. According to the pressure change, the automatic action is realized without external control, the piston is driven to move to the first position by the high pressure and the gap between the piston and the C port, so that the C port is communicated with the D port, the external power source is not needed, the pressure difference between the elastic member and the high pressure pipe C port is used to drive the piston in the three-way valve to move, so that the switching of the three-way valve is realized, and the electromagnetic coil and the pressure taking capillary tube are not needed, so that the structure design and control are simplified.

[0062] As shown in Figure 2 and Figure 3 The present application realizes the automatic switching through the pressure of the C port: when the pressure of the C port rises, the high pressure working medium enters the left piston chamber to drive the piston to move right, the piston stops moving to block the E port, and the C port and the D port are communicated; when the pressure of the C port drops, the elastic member (compression spring) on the right side drives the piston to move left, the pressure continues to drop until the pressure is balanced, the piston stops moving to block the C port, and the E port and the D port are communicated.

[0063] In some embodiments, one end of the inner cavity is provided with a first end cover 24, the other end is provided with a second end cover 25, one end of the elastic member 23 is connected to the second end cover 25; the end of the piston 22 away from the elastic member 23 is connected to be provided with a first positioning column 26, the other end of the piston 22 connected to the elastic member 23 is connected to be provided with a second positioning column 27, and the length of the first positioning column 26 is greater than the minimum distance between the C port C and the first end cover 24, and the length of the second positioning column 27 is less than the minimum distance between the E port E and the second end cover 25. The length of the first positioning column 26 is greater than the minimum distance between the C port C and the first end cover 24, so that the pressure can be introduced from the C port, and when the compressor A is started, the pressure of the C port increases, thereby pushing the piston to move to open the C port and close the E port; and the length of the second positioning column is less than the minimum distance between the E and the second end cover, so that only in the case of reducing or canceling the pressure of the C port, the elastic force of the elastic member can push the piston to move, thereby opening the E port; without manual control or setting control program for control, only by the size of the pressure at the C port can control the movement of the piston, thereby controlling whether to execute the test mode or the recovery mode.

[0064] The application also provides a control method of the refrigerant recovery system for refrigeration equipment testing, characterized in that when the refrigerant recovery system for refrigeration equipment testing simultaneously comprises a compressor A1 and a compressor B9, the control method comprises:

[0065] a judging step of judging whether the operation mode required by the refrigerant recovery system is a refrigeration equipment testing mode or a recovery system recovery mode;

[0066] a control step of controlling the compressor A1 to be opened and the compressor B9 to be closed when the operation mode required by the refrigerant recovery system needs to be operated in the refrigeration equipment testing mode, and controlling the compressor A1 to be closed and the compressor B9 to be opened when the operation mode required by the refrigerant recovery system needs to be operated in the recovery system recovery mode.

[0067] The working principle of the recovery system is described as follows:

[0068] 1) refrigeration equipment testing mode

[0069] In the conventional production test of refrigeration equipment, the indoor unit and the outdoor unit are in a separated state, and the outdoor unit is not configured with a complex electric control system because it is very simple, but the indoor unit is configured with an electric control system, so the indoor unit is mainly tested on line and the refrigeration system is tested for leakage on the production line. Usually, a small amount of refrigerant is filled in the indoor unit for leakage test, the outdoor unit is configured with a test tool with sufficient refrigerant, and the indoor and outdoor units are connected, and the test tool of the outdoor unit is run with the refrigerant therein, after the test is completed, the liquid valve is closed and the refrigerant is completely pressed into the test tool of the outdoor unit by the compressor, including the small amount of refrigerant originally used for leakage test. Since the same test tool of the outdoor unit is used, after testing a plurality of indoor units, a large amount of refrigerant originally used for leakage test of the indoor unit will be accumulated in the test tool of the outdoor unit, resulting in more and more refrigerant in the test tool and more compressor refrigeration oil will be accumulated, which can only be discharged regularly or adjusted to other pressure containers for storage, affecting the test accuracy, causing waste of production cost, prolonging the production time and reducing the production efficiency.

[0070] The production test process involved in the present application is different from the conventional test process described above, and is briefly described as follows:

[0071] The interface E of the recovery system is connected with the gas inlet of the outdoor unit, and the interface F is connected with the liquid outlet of the outdoor unit, after the connection is completed, the recovery system and the outdoor unit will be used as a test tool for on-line test on the production line, only by connecting the interface A and the interface C through the gas fluorine pipe, and connecting the interface B and the interface D through the liquid fluorine pipe, and requiring that the indoor unit is filled with the rated filling amount or the test filling amount instead of the small amount of refrigerant originally used for leakage test. The valves on the interfaces A / BC / D / E / F are all opened, the one-way valves A / B / C / D are automatically turned on or closed according to the pressure difference between the two ends; the vacuum pump is connected with the recovery system and the outdoor unit through the fluorine injection nozzle on the gas valve and / or the liquid valve to perform vacuumizing operation, after the vacuumizing is qualified, the valve of the vacuum gauge is closed, the vacuum pump is closed, then the gas valve and the liquid valve are opened, and the vacuum gauge is removed later.

[0072] Start the refrigeration equipment running test, the high-temperature and high-pressure refrigerant gas discharged from the compressor A pushes the differential pressure three-way valve in the original balanced state to realize channel switching, at this time CD is connected and ED is cut off, and the refrigerant flow circulation is:

[0073] Compressor A1→gas valve 13→interface A141→interface C143→three-way valve CD→oil separator A6→one-way valve D74→interface E145→condenser 3→interface F146→one-way valve C73→interface D144→interface B142→liquid valve 15→expansion valve 5→evaporator 4→compressor A1.

[0074] The separated lubricating oil in the oil separator A is mixed with the liquid refrigerant from the condenser through the capillary tube A and the one-way valve A, and then returns to the indoor unit, so that the content of lubricating oil in the outdoor unit is greatly reduced, the mixed amount of lubricating oil is reduced in the recovery mode, and the total amount of lubricating oil in the indoor unit meets the safe use requirement.

[0075] 2) Recovery system recovery mode

[0076] After the above test mode is tested and qualified, the recovery mode is prepared to run, and there is a transition control between the test mode and the recovery mode:

[0077] a) The outdoor fan is stopped for t seconds, and the high-temperature and high-pressure refrigerant gas discharged by the compressor will flush the liquid refrigerant in the condenser to return to the indoor unit as soon as possible, and then the compressor and the indoor fan are stopped, and the outdoor fan is started to cool the residual refrigerant in the condenser;

[0078] b) The gas valve is closed, and then m seconds are waited to make the indoor unit and the outdoor unit achieve pressure balance as soon as possible, so that the CD stop / ED communication of the pressure differential three-way valve is realized;

[0079] After the above steps a) and b) are completed, the transition control between the test mode and the recovery mode is realized, and then the recovery mode can be started:

[0080] The compressor B is started, the outdoor fan and the indoor fan are started, and the opening degree of the expansion valve of the indoor unit is adjusted to the maximum. The residual refrigerant on the outdoor unit is compressed back to the indoor unit by the compressor B, and the speed of the indoor fan is adjusted according to the pressure of the indoor unit, so that the high-temperature and high-pressure refrigerant gas discharged by the compressor B is condensed and liquefied in the evaporator as soon as possible; the high-speed operation of the outdoor fan of the outdoor unit makes the residual refrigerant liquid in the condenser vaporize as soon as possible to be sucked by the compressor B; the oil separator A can separate and store the lubricating oil of the original refrigeration equipment and realize gas-liquid separation at the same time, so as to prevent the liquid refrigerant that is not completely evaporated from directly returning to the compressor B; the oil separator B can separate the refrigerant and the lubricating oil at the outlet of the compressor B, so as to ensure the normal circulation of the lubricating oil of the compressor B. In summary, the two oil separators can maximize the isolation of the lubricating oil between the two compressors, avoid excessive mixing of the lubricating oil between the two compressors, and ensure that both compressors have sufficient lubricating oil. The refrigerant flow direction in the recovery mode of the recovery system is:

[0081] One-way valve C 73→interface F 146→condenser 3→interface E 145→three-way valve ED→oil separator A 6→compressor B 9→oil separator B 10→one-way valve B 72→interface D 144→interface B 142→liquid valve 15→expansion valve 5→evaporator 4.

[0082] When the suction pressure and / or temperature of the compressor B9 is detected at the critical point Low, indicating that the recovery of refrigerant meets the requirements, the operation of the recovery mode can be stopped: the compressor B9 and the outdoor fan are stopped after the liquid valve is closed, and the indoor fan is stopped after waiting for n seconds.

[0083] After the recovery mode is completed, most of the refrigerant in the recovery system, the outdoor unit, the gas fluorine pipe and the liquid fluorine pipe has been recovered and returned to the indoor unit, and only a small amount of refrigerant gas remains in the pipeline between the liquid valve and the outlet of the one-way valve A / B / C, which is usually within the allowable error of the indoor unit filling amount.

[0084] When the valves A and B are arranged on the interfaces A141 and B142 respectively, closing the valves A and B, and then disconnecting the interfaces A141 and B142, the vacuum degree of the recovery system and the outdoor unit can be maintained. After the next indoor unit is connected, the pipe section between the interface A141 and the gas valve 13, and the pipe section between the interface B142 and the liquid valve 15 need to be vacuumized, the required vacuumization time is greatly shortened, and the loss of lubricating oil caused by frequent vacuumization of the recovery system and the outdoor unit can be avoided. It should be noted that the interfaces A / B / C / D / E / F and the like involved in the present application can use manually or automatically controlled valves.

[0085] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A refrigerant recovery system for testing a refrigeration appliance, characterized by: Compressor A (1), three-way valve (2), condenser (3), oil separator A (6), first pipeline (101), second pipeline (102) and third pipeline (103), the three-way valve (2) includes C port (C), D port (D) and E port (E), one end of the first pipeline (101) is communicated with the C port (C), the other end can be communicated with the exhaust end of the compressor A (1), one end of the second pipeline (102) is communicated with the D port (D), the other end is communicated with the oil separator A (6), one end of the third pipeline (103) is communicated with the E port (E), the other end can be communicated with the condenser (3), when the compressor A (1) starts, run the refrigeration equipment test mode, at this time the C port (C) can be connected with the D port (D), the E port (E) is closed, to realize oil gas separation by entering the oil separator A (6) through the second pipeline (102) through the D port (D); when the compressor A (1) is closed, run the recovery system recovery mode, at this time the E port (E) can be connected with the D port (D), the C port (C) is closed, to realize oil gas separation by entering the oil separator A (6) through the second pipeline (102) through the E port (E).

2. The refrigerant recovery system for refrigeration equipment test according to claim 1, wherein: when the compressor A (1) starts, the mixture of refrigerant and lubricating oil discharged from the exhaust end of the compressor A (1) enters the oil separator A (6) through the first pipeline (101), the C port (C), the D port (D) and the second pipeline (102) for oil gas separation; when the compressor A (1) is closed, the mixture of refrigerant and lubricating oil in the condenser (3) enters the oil separator A (6) through the third pipeline (103), the E port (E), the D port (D) and the second pipeline (102) for oil gas separation.

3. The refrigerant recovery system for refrigeration equipment test according to claim 1 or 2, wherein: further comprising a fourth pipeline (104) and a one-way valve D (74), one end of the fourth pipeline (104) is connected to the upper part of the inside of the oil separator A (6), the other end is communicated with the third pipeline (103), the one-way valve D (74) is arranged on the fourth pipeline (104) to allow fluid to flow from the oil separator A (6) to the third pipeline (103) only.

4. The refrigerant recovery system for refrigeration equipment test according to claim 3, wherein: ​ ​ ​ Further comprising an evaporator (4), an expansion valve (5), a fifth pipe (105), a sixth pipe (106) and a seventh pipe (107), one end of the fifth pipe (105) being able to communicate with the condenser (3) and the other end being able to communicate with the expansion valve (5), one end of the sixth pipe (106) communicating with the expansion valve (5) and the other end communicating with the evaporator (4), one end of the seventh pipe (107) communicating with the inner bottom of the oil separator A (6) and the other end communicating with the fifth pipe (105).

5. The refrigerant recovery system for testing a refrigerating appliance according to claim 4, wherein: A first throttling device (81) and a one-way valve A (71) are provided on the seventh pipe (107), and the one-way valve A (71) is able to allow fluid to flow only from the oil separator A (6) to the fifth pipe (105).

6. The refrigerant recovery system for testing a refrigerating appliance according to claim 4, wherein: Further comprising a compressor B (9), an oil separator B (10), a second throttling device (82), an eighth pipe (108), a ninth pipe (109) and a tenth pipe (110), one end of the eighth pipe (108) communicating with the fourth pipe (104) and the other end communicating with the gas inlet end of the compressor B (9), one end of the ninth pipe (109) communicating with the gas outlet end of the compressor B (9) and the other end communicating with the inside upper portion of the oil separator B (10), one end of the tenth pipe (110) communicating with the inner bottom of the oil separator B (10) and the other end communicating with the eighth pipe (108), and the second throttling device (82) being provided on the tenth pipe (110).

7. The refrigerant recovery system for testing a refrigerating appliance according to claim 6, wherein: Further comprising an eleventh pipe (111) and a one-way valve B (72), one end of the eleventh pipe (111) communicating with the gas outlet of the oil separator B (10) and the other end communicating with the fifth pipe (105), and the one-way valve B (72) being provided on the eleventh pipe (111) to allow fluid to flow only from the oil separator B (10) to the fifth pipe (105).

8. The refrigerant recovery system for testing a refrigerating appliance according to claim 7, wherein: The fourth pipe (104) and the eighth pipe (108) meet at a first meeting position (11), and the tenth pipe (110) also connects to the first meeting position (11); The seventh pipe (107) and the fifth pipe (105) meet at a second meeting position (12), and the eleventh pipe (111) also connects to the second meeting position (12); A one-way valve C (73) is provided on the fifth pipe (105) between the condenser (3) and the second meeting position (12), and the one-way valve C (73) is able to allow fluid to flow only from the condenser (3) to the second meeting position (12).

9. The refrigerant recovery system for testing refrigeration equipment according to claim 8, characterized in that: The first pipeline (101) is further provided with a gas valve (13), an interface A (141) and an interface C (143), the fifth pipeline (105) is provided with a liquid valve (15), an interface B (142) and an interface D (144) between the second connection position (12) and the expansion valve (5), the third pipeline (103) is provided with an interface E (145), and the fifth pipeline (105) is provided with an interface F (146) between the second connection position (12) and the condenser (3); and a fluorine injection nozzle (16) is arranged between the evaporator (4) and the compressor A (1).

10. The refrigerant recovery system for testing refrigeration equipment according to any one of claims 1-9, characterized in that: The three-way valve (2) is a differential pressure type three-way valve, comprising a valve body (21), a piston (22) and an elastic member (23), and the valve body (21) is internally provided with an inner cavity; the D port (D), the C port (C) and the E port (E) are respectively connected with the inner cavity, and the D port (D) is arranged on one side of the valve body (21), and the C port (C) and the E port (E) are respectively arranged on the other side of the valve body (21); The piston (22) and the elastic member (23) are both arranged in the inner cavity; one end of the elastic member (23) is connected with the valve body (21) away from the C port (C), and the other end is connected with the piston (22); The piston (22) has a first position capable of connecting the C port (C) with the D port (D) and completely sealing the E port (E), and a second position capable of connecting the E port (E) with the D port (D) and not completely sealing the C port (C).

11. The refrigerant recovery system for testing a refrigeration appliance of claim 10, wherein: One end of the inner cavity is provided with a first end cover (24), and the other end is provided with a second end cover (25), one end of the elastic member (23) is connected with the second end cover (25); one end of the piston (22) away from the elastic member (23) is connected with a first positioning column (26), and the other end of the piston (22) connected with the elastic member (23) is connected with a second positioning column (27), and the length of the first positioning column (26) is greater than the minimum distance between the C port (C) and the first end cover (24), and the length of the second positioning column (27) is less than the minimum distance between the E port (E) and the second end cover (25).

12. A control method of a refrigerant recovery system for testing a refrigerating apparatus according to any one of claims 1 to 11, characterized by: When the refrigerant recovery system for testing refrigeration equipment simultaneously comprises the compressor A (1) and the compressor B (9), the control method comprises: A judging step of judging whether the operation mode required by the refrigerant recovery system is a refrigeration equipment testing mode or a refrigerant recovery system recovery mode; The control step controls the compressor A (1) to be opened and the compressor B (9) to be closed when the operation mode required by the refrigerant recovery system needs to be operated in the refrigeration equipment test mode; and controls the compressor A (1) to be closed and the compressor B (9) to be opened when the operation mode required by the refrigerant recovery system needs to be operated in the refrigerant recovery system recovery mode.

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