阅读说明：本技术 回油系统及具有其的空调系统 (Oil return system and air conditioning system with same ) 是由 冯维庆 毛守博 李旭 夏鹏 于永全 于 2020-07-02 设计创作，主要内容包括：本发明涉及一种回油系统及具有其的空调系统。该回油系统配置成可用于蒸汽压缩式制冷系统,并且包括：气液分离器,其连接到蒸汽压缩式制冷系统的压缩机的回气管并且设有气液分离器回油口；以及引射器,其设有可连接到蒸汽压缩式制冷系统的高压侧的引射端,可通过气液分离器回油管连接到气液分离器回油口的被引射端,和可连接到压缩机的回气管的出口端；引射器配置成通过引射端可将由来自高压侧的制冷剂或润滑油形成的射流引入引射器中,使得气液分离器内的润滑油借助于射流可被吸出并与射流混合后经由引射器的出口端流向压缩机的回气管。通过上述配置,本发明回油系统利用高压动力即使低温情况下也能高效回油,因此能够兼顾回油效率和压力损失。(The invention relates to an oil return system and an air conditioning system with the same. The oil return system is configured to be usable in a vapor compression refrigeration system and includes: a gas-liquid separator connected to a gas return pipe of a compressor of the vapor compression refrigeration system and provided with a gas-liquid separator oil return port; the ejector is provided with an ejection end which can be connected to the high-pressure side of the steam compression type refrigerating system, an ejected end which can be connected to an oil return port of the gas-liquid separator through an oil return pipe of the gas-liquid separator, and an outlet end which can be connected to an air return pipe of the compressor; the ejector is configured to introduce a jet flow formed by the refrigerant or the lubricating oil from the high-pressure side into the ejector through the ejector end so that the lubricating oil in the gas-liquid separator can be sucked out by means of the jet flow and mixed with the jet flow to a return pipe of the compressor through an outlet end of the ejector. Through the configuration, the oil return system can efficiently return oil even under the condition of low temperature by utilizing high-pressure power, so that the oil return efficiency and the pressure loss can be considered at the same time.)

1. An oil return system configured to be usable with a vapor compression refrigeration system, comprising:

the gas-liquid separator is connected to a gas return pipe of a compressor of the vapor compression refrigeration system and is provided with a gas-liquid separator oil return port; and

the ejector is provided with an ejection end which can be connected to the high-pressure side of the vapor compression refrigeration system, an ejected end which can be connected to an oil return port of the gas-liquid separator through an oil return pipe of the gas-liquid separator, and an outlet end which can be connected to an air return pipe of the compressor; the ejector is configured to introduce a jet of refrigerant or lubricant from the high pressure side into the ejector through the ejector end such that lubricant in the gas-liquid separator is drawn out by the jet and mixed with the jet to flow to a return pipe of the compressor via an outlet end of the ejector.

2. The oil return system of claim 1, further comprising an oil separator connected to the compressor discharge line and provided with an oil separator oil return, the eductor end of the eductor being connected to the oil separator oil return through an oil separator oil return line; the ejector is configured to introduce the jet formed by the lubricating oil from the oil separator into the ejector through the ejector end so that the lubricating oil in the gas-liquid separator can be sucked out by means of the jet and flows to a gas return pipe of the compressor through an outlet end of the ejector after being mixed with the jet.

3. The oil return system according to claim 1 or 2, wherein a first solenoid valve is provided on a pipe connecting the injection end and the high pressure side or on the oil separator oil return pipe, the first solenoid valve being configured to be switchable between an open state and a closed state.

4. The oil return system of claim 3, wherein a first filter and a first capillary tube are further disposed on a pipeline connecting the injection end and the high-pressure side or on the oil separator oil return pipe, the first filter, the first solenoid valve and the first capillary tube are positioned so that the refrigerant from the high-pressure side or the lubricating oil from the oil separator flows through the first filter, the first solenoid valve and the first capillary tube in sequence, and the first capillary tube is configured to throttle the refrigerant from the high-pressure side or the lubricating oil from the oil separator to form the jet flow.

5. The oil return system according to claim 1 or 2, wherein a second solenoid valve is provided on an oil return branch pipe connecting the outlet end of the ejector and the return pipe of the compressor, the second solenoid valve being configured to be switchable between an open state and a closed state.

6. The oil return system of claim 5 wherein, with the eductor end of the eductor connected to the oil separator oil return,

when the first electromagnetic valve and the second electromagnetic valve are both in an open state, lubricating oil from the oil separator and lubricating oil from the gas-liquid separator flow to an air return pipe of the compressor after being mixed by the ejector;

when the first solenoid valve is in a closed state and the second solenoid valve is in an open state, the oil separator is configured to stop oil return, and the gas-liquid separator is configured to return oil by means of gravity and a pressure difference;

when the first electromagnetic valve is in an open state and the second electromagnetic valve is in a closed state, lubricating oil from the oil separator can flow into the gas-liquid separator through the injected end of the injector to heat the lubricating oil in the gas-liquid separator; and is

The oil separator and the gas-liquid separator are configured to stop oil return when both the first solenoid valve and the second solenoid valve are in a closed state.

7. The oil return system of claim 1, wherein the gas-liquid separator oil return pipe is further connected to an auxiliary branch pipe, and a shutoff valve is provided on the auxiliary branch pipe, and the vapor compression refrigeration system can be replenished with refrigerant or lubricating oil through the auxiliary branch pipe when the shutoff valve is in an open state.

8. The oil return system of claim 7 wherein a second capillary tube is further provided in the auxiliary branch to prevent foreign objects from entering the vapor compression refrigeration system.

9. The oil return system of claim 1 wherein a jet nozzle is provided in the eductor to form the jet.

10. An air conditioning system, characterized in that it comprises an oil return system according to any one of claims 1-9.

Technical Field

The invention relates to a refrigeration system, in particular to an oil return system and an air conditioning system with the same.

Background

A vapor compression type refrigeration system generally includes four basic components of a compressor, a condenser, a throttle mechanism, and an evaporator, which form a circuit allowing a refrigerant to circulate therein, and compresses a low-temperature and low-pressure gas refrigerant into a high-temperature and high-pressure gas refrigerant using the compressor. Compressors, such as scroll compressors, centrifugal compressors, screw compressors, and the like, often require lubricating oil to provide lubrication and seal protection to the moving parts thereof during operation. Therefore, when the compressed high-temperature and high-pressure gas refrigerant is discharged from the compressor very quickly, the lubricant oil in the compressor is easily formed into oil vapor and oil droplet particles and discharged together with the gas refrigerant. When the lubricating oil enters the condenser and the evaporator together with the refrigerant, a layer of oil film is formed on the heat transfer wall surface, so that the thermal resistance is increased, the heat transfer effect of the condenser and the evaporator is reduced, and the refrigeration effect is reduced. Therefore, existing refrigeration systems, including but not limited to central air conditioning systems or multi-split systems, typically include an oil separator between the compressor and the condenser to separate the lubricant oil mixed in the refrigerant vapor. An oil separator is typically disposed on the discharge line connected to the discharge end of the compressor to separate the lubricant oil from the refrigerant before the lubricant oil-laden gaseous refrigerant enters the other major components of the refrigeration system. Vapor compression refrigeration systems are also typically provided with a gas-liquid separator to separate the refrigerant from the evaporator into a gaseous refrigerant and a liquid refrigerant before being drawn into the compressor and to allow only the gaseous refrigerant to return to the compressor, thereby avoiding liquid refrigerant from entering the compressor to break lubrication or otherwise damage the compressor. A certain amount of lubricating oil is also generally present in the gas-liquid separator. The oil separator and the gas-liquid separator return the lubricating oil to the return pipe of the compressor through respective return oil pipelines, so that the lubricating oil leaving the compressor can be returned to the compressor in time, otherwise the compressor can be damaged due to the lack of the lubricating oil.

The existing gas-liquid separator has two different oil return modes. Fig. 1 shows one of the oil return methods. As shown in fig. 1, a conventional gas-liquid separator 31 has an inlet pipe 311 and an outlet pipe 312, and most of the inlet pipe 311 and the outlet pipe 312 are located in the gas-liquid separator 31. The inlet pipe 311 is for receiving a low-temperature and low-pressure gas refrigerant (possibly mixed with a liquid refrigerant and a lubricating oil) from the evaporator. The outlet pipe 312 forms a substantially U-shaped row in the gas-liquid separator 31 and may be connected to the suction side of the compressor. Since the outlet of the intake pipe 311 in the gas-liquid separator 31 is open, the refrigerant can flow throughout the gas-liquid separator 31. Due to the action of gravity, the liquid refrigerant and possibly entrained lubricating oil will separate from the gas refrigerant and sink to the bottom of the gas-liquid separator 31, while the gas refrigerant flows in the upper part inside the gas-liquid separator 31. The suction port of the outlet pipe 312 in the gas-liquid separator 31 is positioned at the upper portion of the gas-liquid separator 31 and is offset from the outlet of the inlet pipe 311. With this arrangement, the compressor draws in gaseous refrigerant from the outlet pipe 312. In order to return the lubricating oil settled at the lowermost portion of the gas-liquid separator 31 to the compressor, an oil suction hole 313 is formed at the lowermost portion of the U-shaped outlet pipe 312. In order to prevent foreign substances from entering the outlet pipe 312, a screen 314 is disposed on the oil suction hole 313. The lubricating oil in the gas-liquid separator 31 is sucked into the outlet pipe 312 through the oil suction hole 313 and returned to the compressor with the gas refrigerant. By designing a proper oil suction aperture, the lubricating oil in the gas-liquid separator 31 can be completely sucked away, so that the oil return speed and the efficiency are high. However, since the outlet pipe 312 is long, both the pressure loss and the oil return resistance are large. In another gas-liquid separator, an oil suction port is not arranged on an air outlet pipe, but an oil return port is directly arranged at the bottom of the gas-liquid separator, and an independent oil return pipe for connecting the oil return port and an air return pipe of the compressor is arranged. The lubricating oil at the bottom of the gas-liquid separator returns to the return pipe of the compressor by means of gravity and a relatively small pressure difference. The oil return mode has low efficiency because the pressure difference between the oil return pipe at the bottom of the gas-liquid separator and the air return pipe of the compressor is too small. In addition, in a low-temperature environment, the fluidity of the lubricating oil is deteriorated, and oil cannot be returned in time, which eventually damages the compressor.

Accordingly, there is a need in the art for a new solution to the above problems.

Disclosure of Invention

In order to solve the above-mentioned problems in the prior art, that is, to solve the technical problem that the oil return efficiency and the pressure loss of the existing vapor compression refrigeration system cannot be taken into consideration, the present invention provides an oil return system configured to be usable for a vapor compression refrigeration system, and including: the gas-liquid separator is connected to a gas return pipe of a compressor of the vapor compression refrigeration system and is provided with a gas-liquid separator oil return port; the ejector is provided with an ejection end which can be connected to the high-pressure side of the vapor compression refrigeration system, an ejected end which can be connected to an oil return port of the gas-liquid separator through an oil return pipe of the gas-liquid separator, and an outlet end which can be connected to an air return pipe of the compressor; the ejector is configured to introduce a jet of refrigerant or lubricant from the high pressure side into the ejector through the ejector end such that lubricant in the gas-liquid separator is drawn out by the jet and mixed with the jet to flow to a return pipe of the compressor via an outlet end of the ejector.

In a preferred technical scheme of the oil return system, the oil return system further comprises an oil separator, the oil separator is connected to an exhaust pipe of the compressor and is provided with an oil return port of the oil separator, and an injection end of the injector is connected to the oil return port of the oil separator through an oil return pipe of the oil separator; the ejector is configured to introduce the jet formed by the lubricating oil from the oil separator into the ejector through the ejector end so that the lubricating oil in the gas-liquid separator can be sucked out by means of the jet and flows to a gas return pipe of the compressor through an outlet end of the ejector after being mixed with the jet.

In a preferred embodiment of the oil return system, a first electromagnetic valve is disposed on a pipeline connecting the injection end and the high-pressure side or an oil return pipe of the oil separator, and the first electromagnetic valve is configured to be switchable between an open state and a closed state.

In a preferred embodiment of the above oil return system, a first filter and a first capillary are further disposed on a pipeline connecting the injection end and the high-pressure side or on an oil return pipe of the oil separator, the first filter, the first solenoid valve and the first capillary are positioned such that the refrigerant from the high-pressure side or the lubricating oil from the oil separator flows through the first filter, the first solenoid valve and the first capillary in sequence, and the first capillary is configured to throttle the refrigerant from the high-pressure side or the lubricating oil from the oil separator to form the jet flow.

In a preferred technical solution of the above oil return system, a second electromagnetic valve is provided on an oil return branch pipe connecting the outlet end of the ejector and the air return pipe of the compressor, and the second electromagnetic valve is configured to be switchable between an open state and a closed state.

In the preferable technical scheme of the oil return system, under the condition that the injection end of the injector is connected to the oil return port of the oil separator,

when the first electromagnetic valve and the second electromagnetic valve are both in an open state, lubricating oil from the oil separator and lubricating oil from the gas-liquid separator flow to an air return pipe of the compressor after being mixed by the ejector;

when the first solenoid valve is in a closed state and the second solenoid valve is in an open state, the oil separator is configured to stop oil return, and the gas-liquid separator is configured to return oil by means of gravity and a pressure difference;

when the first electromagnetic valve is in an open state and the second electromagnetic valve is in a closed state, lubricating oil from the oil separator can flow into the gas-liquid separator through the injected end of the injector to heat the lubricating oil in the gas-liquid separator; and is

The oil separator and the gas-liquid separator are configured to stop oil return when both the first solenoid valve and the second solenoid valve are in a closed state.

In a preferred embodiment of the above oil return system, the oil return pipe of the gas-liquid separator is further connected to an auxiliary branch pipe, the auxiliary branch pipe is provided with a stop valve, and when the stop valve is in an open state, the vapor compression refrigeration system can supplement refrigerant or lubricating oil through the auxiliary branch pipe or discharge refrigerant or lubricating oil.

In a preferred embodiment of the above oil return system, a second capillary tube is further provided on the auxiliary branch tube to prevent foreign matters from entering the vapor compression refrigeration system.

In a preferred technical scheme of the oil return system, a jet nozzle capable of forming jet flow is arranged in the ejector.

As will be appreciated by those skilled in the art, the oil return system of the present invention incorporates an eductor in order to improve the oil return efficiency of a vapor compression refrigeration system while ensuring that no significant pressure loss is generated. The ejector has an ejection end, an ejected end, and an outlet end. The injection end is connected to the high-pressure side of the vapor compression refrigeration system. By connecting the ejector end to the high pressure side, a jet can be formed with refrigerant or lubricating oil from the high pressure side, which jet creates a negative pressure in the ejector. The jet may be formed by a configured restriction (e.g., a capillary tube) or by a jet nozzle disposed within the eductor. The end of the ejector, which is ejected, is connected with the oil return port of the gas-liquid separator, and the outlet end of the ejector is connected with the air return pipe of the compressor. Because the gas-liquid separator is positioned at the low-pressure side of the steam compression type refrigerating system, lubricating oil in the gas-liquid separator can be sucked out by means of negative pressure caused by jet flow, is mixed with the jet flow and then flows to a gas return pipe of the compressor through the outlet end of the ejector. Through the configuration, the oil return system can efficiently return oil even under the condition of low temperature by utilizing high-pressure power, so that the oil return efficiency and the pressure loss can be considered, namely, the oil return efficiency is high, and the pressure loss is low. In addition, the injection oil return is utilized, the risk that the compressor sucks liquid refrigerant and/or lubricating oil can be avoided, and the refrigerant and the lubricating oil are changed into gaseous molecules after injection, so that the refrigerant can be gasified at the mixing port of the injector even if the refrigerant sucks the liquid refrigerant.

Preferably, the oil return system of the present invention further comprises an oil separator. The oil separator is connected to the discharge pipe of the compressor and is provided with an oil separator return. It can thus be seen that the oil separator is positioned on the high pressure side of the vapor compression refrigeration system. Therefore, the injection end of the injector can be connected to an oil return port of the oil separator through an oil return pipe of the oil separator. High pressure lubricating oil from an oil separator may be used to form the jet. The jet flow enters the ejector through the ejection end of the ejector and generates negative pressure in the ejector, so that the lubricating oil in the gas-liquid separator is sucked out under the action of the negative pressure, is mixed with the jet flow and then flows to the return air pipe of the compressor through the outlet end of the ejector. The configuration utilizes the high-pressure injection effect of the oil separator and the low-pressure state of the gas-liquid separator, and can realize the common oil return of the oil separator and the gas-liquid separator.

Preferably, a first electromagnetic valve is arranged on a pipeline connecting the ejector end and the high-pressure side or an oil return pipe of the oil separator, and a second electromagnetic valve is arranged on an oil return branch pipe connecting the outlet end of the ejector and an air return pipe of the compressor. Through different combination control of the first electromagnetic valve and the second electromagnetic valve, different requirements of the vapor compression refrigeration system on oil return in different operation modes can be met.

Preferably, the jet flow can be formed by the throttling action of a first capillary tube arranged on a pipeline connecting the ejection end and the high-pressure side or an oil return pipe of the oil separator, can also be formed by a jet flow nozzle in the ejector, or can be formed by the matching of the first capillary tube and the ejection nozzle.

The invention also provides an air conditioning system which comprises any one of the oil return systems. Through this oil return system, not only can guarantee to return the compressor of air conditioning system with the lubricating oil that will leave the compressor in time high-efficiently, prevent that the compressor from receiving the harm, but also can reduce air conditioning system's pressure loss effectively.

Drawings

Preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a prior art gas-liquid separator;

FIG. 2 is a schematic view of a first embodiment of the oil return system of the present invention;

FIG. 3 is a schematic cross-sectional view of an embodiment of an eductor in an oil return system of the present invention;

FIG. 4 is a schematic view of a second embodiment of the oil return system of the present invention;

fig. 5 is a flowchart of an embodiment of a control method of the oil return system of the present invention.

Detailed Description

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.

In order to solve the technical problem that the oil return efficiency and the pressure loss of a vapor compression refrigeration system cannot be considered at the same time, the invention provides an oil return system 1. The oil return system 1 is configured to be usable in a vapor compression refrigeration system (not shown in the drawings), and includes: a gas-liquid separator 12, the gas-liquid separator 12 being connected to a return pipe 21 of a compressor 11 of the vapor compression refrigeration system and provided with a gas-liquid separator oil return port 123; the ejector 14 is provided with an ejector end 142 which can be connected to the high-pressure side of the steam compression refrigeration system, an ejected end 143 which can be connected to the oil return port 123 of the gas-liquid separator through the gas-liquid separator oil return pipe 24, and an outlet end 144 which can be connected to the air return pipe 21 of the compressor 11; the eductor 14 is configured to introduce a jet (not shown) of refrigerant or lubricant from the high pressure side into the eductor 14 through the eductor end 142 such that lubricant within the gas-liquid separator 12 is drawn by the jet and mixed with the jet to flow through the outlet end 144 of the eductor 14 to the return air line 21 of the compressor 11.

Reference herein to a "vapor compression refrigeration system" includes, but is not limited to, a multiple refrigerant line system, or a central air conditioning system, or other refrigeration system having a compressor that compresses a vapor refrigerant. These vapor compression refrigeration systems not only have a refrigeration function, but also provide a heating function, a defrosting function, and the like.

By "high pressure side" as referred to herein is meant the portion of the vapor compression refrigeration system that extends from the discharge end of the compressor up to the condenser in which the refrigerant is typically in a high temperature, high pressure, gaseous or liquid state. Conversely, the portion of the circuit of the vapor compression refrigeration system that extends from the evaporator to the suction side of the compressor may be referred to as the "low pressure side". The gas-liquid separator is arranged between the suction end of the compressor and the evaporator. Therefore, when the vapor compression refrigeration system is operated, the gas-liquid separator is generally in a low-temperature and low-pressure state.

In one or more embodiments, the connection of the eductor end 142 of the eductor 14 to the high pressure side of the vapor compression refrigeration system includes: the bleed end 142 is connected by a line (not shown) directly to the discharge line 22 of the compressor or directly to a high pressure line upstream or downstream of the condenser to form a jet with a small portion of high pressure refrigerant separated from the high pressure side. In this case, the gas-liquid separator 12 is provided with a separate ejector 14. Alternatively, the ejector end 142 is connected to the oil separator oil return port 133 of the oil separator 13 through the oil separator oil return pipe 23 of the oil separator 13 to form a jet flow with high-pressure lubricating oil from the oil separator, so that the oil separator 13 and the gas-liquid separator 12 can be returned together by the ejector 14.

In one or more embodiments, a first solenoid valve 231 may be disposed on the above-described piping or oil separator return pipe 23 to control the oil return of the gas-liquid separator 12 and the oil separator 13 by controlling the first solenoid valve 23. In one or more embodiments, a first capillary tube 233 may also be provided on the above-described piping or oil separator return tube 23. The first capillary tube 233 is configured to throttle high pressure refrigerant from the line or high pressure lube oil from the oil separator return 23 into a desired jet.

Fig. 2 is a schematic view of a first embodiment of the oil return system of the present invention. As shown in fig. 2, the oil return system 1 includes a gas-liquid separator 12, an oil separator 13, and an ejector 14.

As shown in fig. 2, the gas-liquid separator 12 has an intake pipe 121, an outlet pipe 122, and a gas-liquid separator oil return port 123. The intake pipe 121 may be connected to an evaporator (not shown in the drawings), and extends from the top of the gas-liquid separator 12 to the upper portion inside the gas-liquid separator 12. The outlet of the intake pipe 121 is open in the gas-liquid separator 12. Therefore, the low-temperature and low-pressure refrigerant from the evaporator enters the gas-liquid separator 12 in the flow direction B and flows in the gas-liquid separator. Due to the action of gravity, the liquid refrigerant and the entrained lubricating oil will separate from the gas refrigerant in the gas-liquid separator 12, the liquid refrigerant and the lubricating oil sinking down into the lower part of the gas-liquid separator 12, while the gas refrigerant is located in the upper part of the gas-liquid separator 12. Outlet pipe 122 is connected to gas return pipe 21, and the inlet of outlet pipe 122 in gas-liquid separator 12 is positioned at the upper portion in gas-liquid separator 12. One end of the muffler 21 is connected to the suction end 111 of the compressor 11. Therefore, the compressor 11 directly sucks the gas refrigerant from the gas-liquid separator 12 through the return pipe 21. As shown in fig. 2, a gas-liquid separator oil return port 123 is provided at an intermediate position of the bottom of the gas-liquid separator 12. The lubricating oil is generally located at the lowermost portion of the gas-liquid separator 12 because it is heavier than the refrigerant. The provision of the gas-liquid separator oil return port 123 at the bottom of the gas-liquid separator 12 thus facilitates oil return, particularly in the case of oil return by gravity. Alternatively, the gas-liquid separator oil return port 123 may be disposed at other positions of the gas-liquid separator 12 below the lubricant oil level or the bottom thereof, as necessary. The gas-liquid separator return port 123 is connected to the drawn end 143 of the eductor 14 by a gas-liquid separator return pipe 24.

In one or more embodiments, gas-liquid separator return line 24 may also be connected to an auxiliary branch line 26 (see FIG. 4). The auxiliary branch 26 is connectable to an external device (not shown) via a shut-off valve 261. The external device may be, for example, a refrigerant storage tank, a lubricant storage tank, or an empty tank. When the shutoff valve 261 is opened, the refrigerant or the lubricating oil can be supplied to the refrigeration system through the auxiliary branch pipe 26 and can be discharged from the refrigeration system. Optionally, a second capillary tube 262 may be further provided on the auxiliary branch 26 to prevent foreign materials from entering the refrigeration system. Optionally, a second filter 241 may be provided on the gas-liquid separator return pipe 24.

As shown in fig. 2, the oil separator 13 has an inlet end 131, an outlet end 132, and an oil separator oil return opening 133. The inlet 131 is connected to the discharge line 22 of the compressor 11 to receive high pressure gaseous refrigerant from the compressor. The discharge pipe 22 is connected to the discharge end 112 of the compressor 11. The inlet end 131 is typically disposed at an upper portion or top of the oil separator 13. The high pressure gaseous refrigerant separates from the lubricating oil carried by the refrigerant in the oil separator 13 and then exits the oil separator 13 in the flow direction a from the gas outlet end 132 at the top of the oil separator 13. The lubricating oil separated from the high-pressure gas refrigerant sinks to the bottom of the oil separator 13 by gravity. An oil separator return port 133 is positioned at the bottom of the oil separator 13 and is connected to an eductor end 142 of the eductor 14 by an oil separator return pipe 23.

In one or more embodiments, as shown in fig. 2, a first solenoid valve 231 is disposed on the oil separator return pipe 23. The first solenoid valve 231 is configured to be switchable between an open and a closed state. When the vapor compression refrigeration system is operated for a long time (for example, for more than 8 hours), the first solenoid valve 231 may be in a normally open state. When the vapor compression refrigeration system is operated, the first solenoid valve 231 may also be controlled to be intermittently opened and closed, if necessary, for example, after the first predetermined period of time in the open state, the first solenoid valve 231 may be switched to the closed state for a second predetermined period of time, and then the first solenoid valve 231 may be opened again, and the above-described control steps may be repeatedly performed. In the intermittent opening and closing mode, the opening time of the first solenoid valve 231 is generally longer than the closing time. When the vapor compression refrigeration system stops operating, the first solenoid valve 231 is normally in a closed state.

In one or more embodiments, as shown in fig. 2, a first capillary tube 233 is also provided on the oil separator return tube 23. The first capillary tube 233 can throttle the high-pressure lubrication oil from the oil separator 13 into a jet flow by an appropriate configuration. The jet then enters the eductor 14 through the eductor end 142 of the eductor 14 and creates a negative pressure therein. Under the action of the negative pressure, the lubricating oil in the gas-liquid separator 12 is sucked into the ejector 14 through the ejection end 143, mixed with the jet flow, and then exits from the outlet end 144 of the ejector 14 to flow along the oil return branch pipe 25 to the return pipe 21 of the compressor 11. Alternatively, the first capillary 233 is eliminated, and an ejector nozzle 146 (see fig. 3) is provided in the ejector 14. A jet is formed through the injection nozzle 146. Alternatively, the first capillary 233 cooperates with the injection nozzle 146 to form a jet. Optionally, a first filter 232 may also be disposed on the oil separator return pipe 23, the first filter 232 being positioned between the oil separator return opening 133 and the first solenoid valve 231.

As shown in fig. 2, the eductor end 142 of the eductor 14 communicates with the oil separator return pipe 23, the eductor end 143 thereof communicates with the gas-liquid separator return pipe 24, and the outlet end 144 thereof communicates with the return manifold 25. In one or more embodiments, as shown in FIG. 2, the return air line 21 of the compressor 11 is relatively short, while the return manifold 25 is relatively long.

Fig. 3 is a schematic cross-sectional view of an embodiment of an eductor in an oil return system of the present invention. As shown in fig. 3, the eductor 14 defines an eductor chamber 145 within its body 141. The injection cavity 145 is in communication with the injection end 142, the injected end 143, and the outlet end 144, respectively. As shown in fig. 3, the eductor chamber 145 has a tapered section of length L that tapers in inner diameter in a direction toward the outlet end 144. In order to provide a stable forward propulsion of the jet in the eductor 14, the length L of the tapered section may be set in the range of 2-5 times the internal diameter D of the tube at the outlet end 144 so that a negative pressure is created around the jet just as it enters the eductor chamber 145. By this negative pressure, the lubricating oil in the gas-liquid separator can be actively sucked into the ejector 14 through the ejection end 143. In one or more embodiments, as shown in fig. 3, an injection nozzle 146 is disposed within the injection chamber 145, and the injection nozzle 146 is in direct communication with the injection end 142. Thus, the jet nozzle 146 can cooperate with the first capillary 233 to create a suitable jet within the jet chamber 145. Alternatively, the eductor 14 may eliminate the eductor nozzle 146 and the oil return system of the present invention may rely solely on the first capillary tube 233 to create the jet.

Fig. 4 is a schematic view of a second embodiment of the oil return system of the present invention. As shown in fig. 4, a second solenoid valve 251 is provided in the oil return branch pipe 25. The second solenoid valve 251 is configured to be switchable between an open and a closed state. As shown in FIG. 4, in one or more embodiments, the return air pipe 21 is configured to be substantially U-shaped and substantially longer than the return branch pipe 25. The return branch pipe 25 may extend horizontally to the U-shaped bottom of the return pipe 21 and be connected to the return pipe 21. In one or more embodiments, as shown in FIG. 4, a gas-liquid separator return line 24 is connected to an auxiliary branch line 26. The auxiliary branch 26 is connectable to an external device (not shown) via a shut-off valve 261. The external device may be, for example, a refrigerant storage tank, a lubricant storage tank, or an empty tank. When the shutoff valve 261 is opened, the refrigerant or the lubricating oil can be supplied to the refrigeration system through the auxiliary branch pipe 26 and can be discharged from the refrigeration system. A second capillary tube 262 is also provided on the auxiliary branch 26 to prevent foreign materials from entering the refrigeration system. The gas-liquid separator return pipe 24 is provided with a second filter 241.

For the oil return system shown in fig. 4, different requirements of the vapor compression refrigeration system on oil return in different operation modes can be met by controlling different switch combinations of the first electromagnetic valve 231 and the second electromagnetic valve 251.

Watch 1

As shown in the first table, four different oil return modes can be realized by the combined control of the switches of the first solenoid valve 231 and the second solenoid valve 251. When both the first electromagnetic valve 231 and the second electromagnetic valve 251 are opened, the lubricating oil in the gas-liquid separator 12 is drawn into the ejector 14 by forming a jet flow of the high-pressure lubricating oil from the oil separator 13 with the aid of the jet flow. The lubricating oil from the oil separator 13 and the lubricating oil from the gas-liquid separator 12 are mixed in the ejector 14, and then flow together along the oil return branch pipe 25 to the gas return pipe 21, and then return to the compressor 11 through the suction end 111 of the compressor 11. When the first solenoid valve 231 is closed and the second solenoid valve 251 is opened, the oil separator 13 stops oil return, so that no jet is formed in the ejector 14. The lubricating oil in the gas-liquid separator 12 flows into the ejector 14 by gravity and pressure difference, and then flows to the gas return pipe 21 through the oil return branch pipe 25. When the first electromagnetic valve 231 is opened and the second electromagnetic valve 251 is closed, the high-pressure lubricating oil from the oil separator 13 can enter the gas-liquid separator 12 after passing through the injection end 142 and the injected end 143 of the injector 14 in sequence, and the lubricating oil in the gas-liquid separator 12 can be heated. When both the first solenoid valve 231 and the second solenoid valve 251 are closed, the oil separator 13 and the gas-liquid separator 12 stop oil return.

Watch two

Table two above lists that different switch combination controls of the first solenoid valve 231 and the second solenoid valve 251 can correspond to different operation conditions of the vapor compression refrigeration system. As shown in table two, when the first solenoid valve 231 and the second solenoid valve 251 are both opened, the oil separator 13 and the gas-liquid separator 12 return oil together, and thus, the present invention is applicable to the basic operation conditions of the vapor compression refrigeration system, i.e., the ordinary operation conditions, such as the refrigeration condition and the heating condition. When the vapor compression refrigeration system is operated at an ultra-low temperature, since the fluidity of the lubricating oil in the gas-liquid separator 12 becomes poor, it is necessary to perform the intermittent heating. For this demand, the first solenoid valve 231 is opened, and the second solenoid valve 251 is intermittently closed. This allows the high-pressure lubricating oil in the oil separator 13 to be introduced into the gas-liquid separator 12 and heats the lubricating oil therein. For example, the first solenoid valve 231 is opened and the second solenoid valve 251 is closed for, for example, 10 minutes or other suitable period of time. After 10 minutes, the second solenoid valve 251 is then opened, and the first solenoid valve 231 remains open for, for example, 1 hour or other suitable period of time. After 1 hour, the step of closing the second solenoid valve 251 is repeated, if necessary. When the vapor compression refrigeration system is operating in the defrosting mode or the oil return mode, the oil separator 13 needs to stop oil return, and therefore, the first solenoid valve 231 is closed and the second solenoid valve 251 is opened, so that the gas-liquid separator 12 can still return oil by means of gravity and a pressure difference. When the vapor compression refrigeration system is stopped, both the first solenoid valve 231 and the second solenoid valve 251 are in the closed state.

Watch III

As shown in the third table, by controlling the opening and closing of the first solenoid valve 231 and the second solenoid valve 251, it is also possible to control the manner of discharging the lubricating oil from the vapor compression refrigeration system and adding the lubricating oil to the refrigeration system. For example, when it is necessary to discharge the lubricating oil from the gas-liquid separator 12, the refrigeration system is stopped and left for, for example, 24 hours or other suitable time while both the first electromagnetic valve 231 and the second electromagnetic valve 251 are in the closed state. In this case, the lubricating oil of the gas-liquid separator 12 may be slowly discharged and then may be discharged to an external storage device via the auxiliary branch 26. In order to discharge the lubricating oil in the oil separator 13, the refrigeration system may be operated at a low frequency, with the first solenoid valve 231 open and the second solenoid valve 251 closed, so that the lubricating oil in the oil separator 13 may be slowly drained and may then be discharged to an external storage device via the auxiliary branch 26. When the refrigeration system needs to be lubricated, both the first solenoid valve 231 and the second solenoid valve 251 may be closed and the refrigeration system is in operation. In this case, a small amount of high-pressure refrigerant may be mixed into the lubricant tank, and then the lubricant may be added by inverting the tank.

For the oil return system shown in fig. 4, the control can be performed based on different working conditions of the vapor compression refrigeration system. The control method determines an operation mode in which the vapor compression refrigeration system is located, and controls opening or closing of the first solenoid valve 231 and the second solenoid valve 251 based on the operation mode. The operating modes include, but are not limited to, a shutdown mode, a cooling mode, a heating mode, a defrost mode, and an oil return mode. In the heating mode, the control method further determines whether the ambient temperature is lower than a predetermined temperature value. When the ambient temperature is lower than the predetermined temperature value, the first electromagnetic valve 231 is opened, and the second electromagnetic valve 251 is intermittently closed to intermittently heat the gas-liquid separator 12.

Fig. 5 is a flowchart of an embodiment of a control method of the oil return system of the present invention. As shown in fig. 5, in step S1, it is determined whether or not the vapor compression refrigeration system is in a shutdown state. When the refrigeration system is in a shutdown state, the control method proceeds to step S2 to close both the first solenoid valve 231 and the second solenoid valve 251. When the refrigeration system is in operation, control determines whether the refrigeration system is defrosting or scavenging in step S3. If so, the control method proceeds to step S4, where the first solenoid valve 231 is closed and the second solenoid valve 251 is opened. If the refrigeration system is not performing defrost or oil return, control may proceed to step S5 to determine if the refrigeration system is operating in a heating mode. If so, control proceeds to step S6 to determine whether the ambient temperature Ta0 is less than a predetermined temperature value, such as 10℃ or other suitable temperature value. If the ambient temperature Ta0 is less than the predetermined temperature value, control proceeds to step S7, where the first solenoid valve 231 is opened and the second solenoid valve 251 is closed interstitially to heat the lube oil in the gas-liquid separator 12 with the lube oil in the oil separator 13. For example, the first solenoid valve 231 is kept open all the time, the second solenoid valve 251 is closed for 10 minutes, and then the second solenoid valve 251 is opened for 1 hour; the step of closing the second solenoid valve 251 is then repeated. When the ambient temperature Ta0 is not less than the predetermined temperature value, control may proceed to step S9 with both the first solenoid valve 231 and the second solenoid valve 251 open. If the refrigeration system is not operating in the heating mode, control proceeds to step S8 to determine if the refrigeration system is operating in the cooling mode. If so, the control method proceeds to step S9 where both the first solenoid valve 231 and the second solenoid valve 251 are opened. If the refrigeration system is not operating in the cooling mode, the control process ends.

The present invention also relates to an air conditioning system having any one of the oil return systems 1 described above, including but not limited to a multiple unit system or other suitable air conditioning system. Through the oil return system 1, the air conditioning system has high oil return efficiency of lubricating oil and low pressure loss. The air conditioning system can control the oil return system based on the control method.

So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.