Air conditioning system

Abstract

The invention provides an air conditioning system, and relates to the technical field of air conditioners. The air conditioning system comprises a compressor, an oil separator and an economizer, the compressor is provided with an exhaust port, an air suction port and an air supply port which are arranged at intervals, the exhaust port communicates with an inlet of the oil separator, and a first flow channel of the economizer communicates with the air supply port; the air conditioning system further comprises an oil return loop, the oil return loop comprises a main pipeline, a first branch and a second branch, an inlet of the main pipeline is communicated with an oil return opening of the oil separator, the first branch is communicated between an outlet of the main pipeline and the air suction opening, the second branch is communicated between an outlet of the main pipeline and the air supply opening, and the first branch and the second branch are arranged in parallel. The first flow channel and the second branch are arranged in parallel; and a first control valve is arranged on the first branch, and the first control valve is configured to respond to the working state of the economizer to adjust opening and closing, so that when no refrigerant exists at the air supply port or the pressure of the refrigerant is too high, the compressor can normally return oil.

Description

Technical Field

[0001] The present application relates to the technical field of air conditioning, and in particular to an air conditioning system. Background Art

[0002] The oil discharge rate of the variable frequency compressor is relatively high when running at high frequency. In order to prevent the compressor from lacking oil and wearing, and also to prevent a large amount of refrigerant oil from entering the heat exchanger and affecting the heat exchange effect, an oil separator is generally installed on the compressor exhaust pipe to separate the refrigerant oil in the exhaust and return it to the compressor.

[0003] In conventional air conditioning systems, refrigerant oil flows from the oil separator outlet through a capillary throttle before returning to the compressor's intake or supply port. When refrigerant oil returns to the compressor from the intake port, since the compressor also draws refrigerant through the intake port, this affects the compressor's intake capacity, reducing the unit's cooling capacity. However, when refrigerant oil returns to the compressor's compression chamber from the supply port, this does not affect the compressor's intake capacity. Therefore, the pressure at the supply port is higher than the intake port pressure, requiring less compressor power, thus ensuring compressor energy efficiency. In air conditioning systems, the corresponding compressor supply port is typically equipped with a supply pipe. Some refrigerant in the economizer absorbs heat from another portion of the refrigerant and evaporates into gas, causing the remaining portion of the refrigerant to be supercooled. This evaporated gas in the economizer can be transported back to the compressor through the supply pipe. However, when the supply pipe pressure is too high, oil return from the supply port can increase the pressure in the compressor's compression chamber, causing the compressor to overload. When the economizer is not operating, oil return from the supply port poses the risk of oil shock to the compressor. Summary of the Invention

[0004] Based on this, it is necessary to provide an air conditioning system that can ensure normal oil return of the compressor under conditions where the pressure of the air supply pipeline is high or the economizer is not working.

[0005] An air-conditioning system includes a compressor, an oil separator and an economizer, the compressor having an exhaust port, an intake port and an air supply port arranged at intervals, the exhaust port being connected to the inlet of the oil separator, and the first flow channel of the economizer being connected to the air supply port; the air-conditioning system also includes an oil return circuit, the oil return circuit including a main line, a first branch line and a second branch line, the inlet of the main line being connected to the oil return port of the oil separator, the first branch line being connected between the outlet of the main line and the intake port, the second branch line being connected between the outlet of the main line and the air supply port, the first branch line and the second branch line being arranged in parallel, and the first flow channel and the second branch line being arranged in parallel; a first throttling device is provided between the inlet and outlet of the main line, a first control valve is provided on the first branch line, and the first control valve is configured to adjust opening and closing in response to the working state of the economizer.

[0006] It is understood that the high-temperature refrigerant gas in the compressor enters the oil separator, where oil droplets in the refrigerant gas are separated from the refrigerant gas. The oil droplets converge and are discharged from the oil return port into the oil return circuit. The refrigerant oil flows from the main line to the first branch and the second branch. The opening and closing of the first control valve is controlled according to the operating status of the economizer to appropriately select the refrigerant oil to return to the compressor from the intake port or the supply port. This ensures that when the economizer is not operating or the refrigerant gas pressure at the compressor supply port is too high, the refrigerant oil entering the compressor through the supply port and causing damage to the compressor is reduced or prevented. When the refrigerant gas pressure output by the economizer is not too high, the first control valve closes, allowing the refrigerant oil to flow from the second branch to the supply port, thereby ensuring energy efficiency for cooling or heating and reducing power consumption of the compressor.

[0007] In one embodiment, the air-conditioning system further includes an air supply pipeline, the first flow channel is connected to the air supply port through the air supply pipeline, and the second branch is connected to the air supply port through the air supply pipeline; the air-conditioning system further includes a main circuit, the economizer includes a second flow channel, the economizer is connected to the main circuit through the second flow channel, the first flow channel and the second flow channel are arranged in parallel, and the first flow channel can be connected to the main circuit through a first expansion valve; the first control valve is configured to adjust the opening and closing in response to the opening and closing signal of the first expansion valve and the pressure signal or temperature signal of the air supply pipeline.

[0008] It can be understood that the air supply pipeline can transport the gas output by the economizer to the air supply port. The pressure signal or temperature signal on the air supply pipeline can be used to intuitively obtain the pressure level of the air supply pipeline. Combined with the opening and closing of the first expansion valve, the opening and closing of the first control valve can be adjusted, making the adjustment of the first control valve more reliable.

[0009] In one embodiment, when the first expansion valve is closed, the first control valve is configured to open in response to a closing signal of the economizer; when the first expansion valve is opened, the air supply pipeline is provided with a limited pressure P of the refrigerant, and the actual pressure of the air supply pipeline is P1; when P1≤P, the first control valve is configured to close in response to the signal of the actual pressure; if P1>P, the first control valve is configured to open in response to the signal of the actual pressure; or, when the first expansion valve is opened, the air supply pipeline is provided with a limited temperature T of the refrigerant, and the actual temperature of the air supply pipeline is T1; when T1≤T, the first control valve is configured to close in response to the signal of the actual temperature; if T1>T, the first control valve is configured to open in response to the signal of the actual temperature.

[0010] It is understandable that when the first expansion valve is opened, the gas pressure value output by the economizer can be obtained through the actual pressure or actual temperature signal, and the actual pressure can be compared with the limited pressure or the actual temperature can be compared with the limited temperature to timely adjust the opening and closing of the first control valve, so that the adjustment is more reference-based.

[0011] In one embodiment, the oil return circuit also includes a second oil return pipeline and an oil return main pipeline. The inlet of the main pipeline is connected to the oil return port of the oil separator through the oil return main pipeline. The second oil return pipeline is connected to the oil return main pipeline. The second oil return pipeline and the main pipeline are arranged in parallel. The second oil return pipeline is connected to the intake port. A second control valve is connected to the second oil return pipeline, and the second control valve is configured to adjust opening and closing in response to frequency changes of the compressor.

[0012] It is understood that the oil return main pipe can input the refrigerant oil into the main line and the second oil return line respectively. By adding a second oil return line, the flow rate of refrigerant oil returning to the compressor per unit time is increased, so that when the compressor discharges oil at a high frequency, the large amount of refrigerant oil in the oil separator can be discharged in time.

[0013] In one embodiment, the frequency of the compressor is F; the high-frequency range of the compressor is set to be above F1, the low-frequency range of the compressor is set to be below F1, and the adjustment difference is △n, △n≥0; when F≥F1+△n, the second control valve is configured to open in response to the compressor being in a high-frequency state; when F≤F1-△n, the second control valve is configured to close in response to the compressor being in a low-frequency state.

[0014] It is understandable that the frequency of the compressor is related to the oil discharge rate of the compressor. The oil discharge rate of the compressor can be obtained according to the frequency of the compressor, and the opening and closing of the second control valve can be adjusted in time, so that the adjustment is reference and accurate.

[0015] In one embodiment, a second throttle member is provided on the second oil return pipeline, and the second throttle member is located between the outlet of the second control valve and the air intake port.

[0016] It can be understood that the second throttling member is provided to facilitate the refrigeration oil to flow back to the compressor from the second oil return pipeline in a continuous and stable manner.

[0017] In one embodiment, the first throttling member is configured as a first capillary tube, and the second throttling member is configured as a second capillary tube; the length of the second capillary tube is h, the length of the first capillary tube is L, h = (1 to 3) L; and / or, the inner diameter of the second capillary tube is d, the inner diameter of the first capillary tube is D, d = (0.3 to 1) D.

[0018] As can be understood, using a capillary tube as a throttling element is cost-effective. By defining the length and inner diameter relationship between the first and second capillary tubes, more refrigerant oil can flow into the main line. When the economizer is operating normally, more refrigerant oil can flow from the air supply port into the compressor, thereby improving the energy efficiency of the air conditioning system.

[0019] In one embodiment, the main circuit further includes a gas-liquid separator, the outlet of the gas-liquid separator is connected to the air intake port; the outlet of the first branch and / or the outlet of the second oil return pipeline are connected to the gas-liquid separator.

[0020] It is understandable that the refrigeration oil flows back to the compressor after passing through the gas-liquid separator, which is beneficial to buffering the return of the refrigeration oil.

[0021] In one embodiment, a one-way valve is provided on the second branch or the air supply pipeline; or a third throttling element is provided on the second branch.

[0022] It is understandable that the setting of the one-way valve prevents the refrigerant in the air supply pipeline from flowing into the oil return pipeline. The setting of the third throttling element can further limit the flow of the refrigeration oil.

[0023] In one embodiment, a fourth throttling element is provided on the first branch path, and the fourth throttling element is connected between the first control valve and the air intake.

[0024] It can be understood that the provision of the fourth throttling element is beneficial for further limiting the flow of the refrigeration oil on the basis of the first throttling element, thereby improving the oil return stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic diagram of a first embodiment of an air-conditioning system provided in this application;

[0027] Figure 2 A schematic diagram of a second embodiment of an air-conditioning system provided in this application;

[0028] Figure 3 A schematic diagram of a third embodiment of an air-conditioning system provided in this application;

[0029] Figure 4 A schematic diagram of a fourth embodiment of an air-conditioning system provided in this application;

[0030] Figure 5 This is a schematic diagram of the fifth embodiment of the air-conditioning system provided in this application.

[0031] Figure numerals: 100, air conditioning system; 10, main circuit; 11, compressor; 111, exhaust port; 112, intake port; 113, air supply port; 12, oil separator; 13, first heat exchanger; 14, second heat exchanger; 15, economizer; 151, first flow channel; 152, second flow channel; 161, first expansion valve; 162, second expansion valve; 17, gas-liquid separator; 18, four-way valve; 20, oil return circuit; 21, first oil return pipeline; 211, main pipeline; 212, first branch; 213, second branch; 22, second oil return pipeline; 23, oil return main pipeline; 31, first throttling device; 32, second throttling device; 33, third throttling device; 34, fourth throttling device; 41, first control valve; 42, second control valve; 43, one-way valve; 50, air supply pipeline. DETAILED DESCRIPTION

[0032] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0033] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of this application are for illustrative purposes only and do not represent the only implementation method.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0035] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it can mean that the first feature is directly in contact with the second feature, or the first feature and the second feature are indirectly in contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it can mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature. When a first feature is "below," "below," or "below" a second feature, it can mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is lower in level than the second feature.

[0036] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more of the relevant listed items.

[0037] See also Figures 1 to 5 The present application provides an air conditioning system 100, which includes a compressor 11, an oil separator 12 and an economizer 15; the compressor 11 has an exhaust port 111, an air intake port 112 and an air supply port 113 arranged at intervals; the exhaust port 111 is connected to the inlet of the oil separator 12, and the first flow channel of the economizer 15 is connected to the air supply port 113; the air conditioning system 100 also includes an oil return circuit 20, the oil return circuit 20 includes a main line 211, a first branch line 212 and a second branch line 213, the inlet of the main line 211 is connected to the oil separator 12, and the first branch line 212 and the second branch line 213 are connected. The return oil port of the economizer 12 is connected, the first branch 212 is connected between the outlet of the main line 211 and the air intake port 112, the second branch 213 is connected between the outlet of the main line 211 and the air supply port 113, the first branch 212 and the second branch 213 are arranged in parallel, and the first flow channel and the second branch 213 are arranged in parallel; a first throttling member 31 is provided between the inlet and outlet of the main line 211, and a first control valve 41 is provided on the first branch 212. The first control valve 41 is configured to adjust the opening and closing in response to the working state of the economizer 15.

[0038] In this way, the compressor 11 can output high-temperature and high-pressure refrigerant gas, which carries oil droplets of refrigeration oil. The oil separator 12 can separate the oil droplets in the refrigerant gas. Then, the refrigerant gas continues to circulate for cooling or heating. The separated refrigeration oil gathers at the return oil port and enters the return oil circuit 20.

[0039] In the oil return circuit 20, the refrigerant oil first passes through the main line 211. The first throttling member 31 on the main line 211 can limit the flow of the refrigerant oil, promote the continuous and stable return of the refrigerant oil, and avoid the refrigerant oil returning quickly and causing the refrigerant gas to leak from the oil return port into the oil return circuit 20.

[0040] Furthermore, the economizer 15 primarily serves to supercool the refrigerant, with some of the refrigerant evaporating into gas within the economizer 15 and then flowing back to the compressor 11 through the air inlet 113. When the economizer 15 is not operating, there is no stable flow of refrigerant gas into the air inlet 113, meaning that the refrigerant gas hardly flows. At this time, oil return from the air inlet 113 can easily cause oil slugging in the compressor 11. Furthermore, without refrigerant gas flowing, the refrigeration oil cannot flow smoothly and evenly back to the compressor 11 from the air inlet 113. When the economizer 15 is operating and the refrigerant gas output is under excessive pressure, oil return from the air inlet 113 can easily cause an overload in the compressor 11. Therefore, for the two operating conditions of the above-mentioned economizer 15, the first control valve 41 can be adjusted to open. Since the pressure at the exhaust port 111 of the compressor 11 is the highest, the pressure at the air supply port 113 is second, and the pressure at the air intake port 112 is the lowest, the pressure difference between the exhaust port 111 and the air intake port 112 is greater than the pressure difference between the exhaust port 111 and the air supply port 113. After the first control valve 41 is opened, the refrigerant oil flows into the first branch 212 under the action of the pressure difference, and flows back to the compressor 11 from the air supply port 112, thereby preventing the refrigerant oil from flowing into the air supply port 113 and causing the compressor 11 to overload or oil shock.

[0041] In addition, when the economizer 15 is operating and the output refrigerant gas pressure is not too high, the first control valve 41 can be closed, allowing all the refrigerant oil to flow to the second branch 213, eliminating the impact of return oil on the effective intake volume of the compressor 11, ensuring that the refrigerant output flow rate remains unchanged, thereby maintaining the overall energy efficiency of the air-conditioning system 100.

[0042] Furthermore, the air conditioning system 100 includes a main circuit 10, which includes a compressor 11, an oil separator 12, a first heat exchanger 13, an economizer 15 and a second heat exchanger 14 connected in sequence. For ease of explanation, the main circuit 10 is first described in detail.

[0043] like Figures 1 to 5 As shown, in a specific embodiment, the main circuit 10 further includes a gas-liquid separator 17 and a four-way valve 18. One of the flow ports of the four-way valve 18 is connected to the outlet of the oil separator 12, and the remaining three flow ports are connected to the first heat exchanger 13, the second heat exchanger 14, and the gas-liquid separator 17 in a one-to-one correspondence. The inlet of the gas-liquid separator 17 is connected to the flow port of the four-way valve 18, and the outlet of the gas-liquid separator 17 is connected to the intake port 112 of the compressor 11.

[0044] In a specific embodiment, the air-conditioning system 100 further includes an air supply pipeline 50, and the first flow channel 151 is connected to the air supply port 113 through the air supply pipeline 50 to input the evaporated gas in the economizer 15 to the air supply port 113; the second branch 213 is connected to the air supply port 113 through the air supply pipeline 50 to facilitate oil return from the air supply port 113; the economizer 15 includes a second flow channel 152, and the economizer 15 is connected to the main circuit 10 through the second flow channel 152. The first flow channel 151 and the second flow channel 152 are arranged in parallel, and the first flow channel 151 can be connected to the main circuit 10 through the first expansion valve 161.

[0045] Specifically, the air-conditioning system 100 also includes a second expansion valve 162, the first flow channel 151 is connected between the first expansion valve 161 and the air supply pipeline 50, the inlet of the second flow channel 152 is selectively connected to one of the first heat exchanger 13 and the second heat exchanger 14, the outlet of the second flow channel 152 is connected to the inlet of the second expansion valve 162, the inlet of the first expansion valve 161 is connected between the inlet of the second expansion valve 162 and the outlet of the second expansion valve 152, and the outlet of the second expansion valve 162 is selectively connected to one of the first heat exchanger 13 and the second heat exchanger 14; the first flow channel 151 exchanges heat with the second flow channel 152.

[0046] As shown in Figure 1 Figure 5 As shown, the main circuit 10 has two working conditions: cooling mode and heating mode. The white arrows in the figure represent the refrigerant flow direction in the heating mode, and the black arrows in the figure represent the refrigerant flow direction in the cooling mode.

[0047] In the refrigeration mode, the compressor 11 outputs high-temperature and high-pressure refrigerant gas. After the refrigerant oil is separated from the refrigerant gas by the oil separator 12, the refrigerant gas enters the four-way valve 18. The four-way valve 18 outputs the refrigerant gas to the first heat exchanger 13. After heat exchange in the first heat exchanger 13, the refrigerant enters the economizer 15 for supercooling. The refrigerant flows into the second flow channel 152. Part of the refrigerant enters the first flow channel 151 after throttling by the first expansion valve 161, absorbs the heat of the refrigerant in the second flow channel 152 and evaporates into gas. This part of the gaseous refrigerant returns to the compressor 11 from the air supply line 50. , which reduces the temperature of the refrigerant in the second flow channel 152. Then, the cooled refrigerant in the second flow channel 152 is throttled and depressurized by the second expansion valve 162 to form a low-temperature, low-pressure refrigerant liquid. The low-temperature, low-pressure refrigerant flows into the second heat exchanger 14 for heat exchange, and absorbs heat from the air through the second heat exchanger 14 to cool the air. The refrigerant after absorbing heat evaporates into gas, passes through the four-way valve 18, and flows into the gas-liquid separator 17 to separate the liquid droplets. The separated refrigerant gas returns to the compressor 11 from the air intake 112 to continue the refrigeration cycle.

[0048] In the heating mode, the compressor 11 outputs high-temperature and high-pressure refrigerant gas. After the refrigerant oil is separated from the refrigerant gas by the oil separator 12, it enters the four-way valve 18. The four-way valve 18 outputs the refrigerant gas to the second heat exchanger 14. The high-temperature and high-pressure refrigerant gas releases heat through the second heat exchanger 14, thereby causing the surrounding air to heat up. After the refrigerant releases heat and cools down, it enters the economizer 15 for supercooling. The refrigerant flows into the second flow channel 152, and part of the refrigerant enters the first flow channel 151 after being throttled by the first expansion valve 161, absorbs the heat of the refrigerant in the second flow channel 152 and evaporates. Into gas, this part of the gaseous refrigerant returns to the compressor 11 from the air supply pipe 50, so that the temperature of the refrigerant in the second flow channel 152 is reduced. Then, the cooled refrigerant is throttled and reduced in pressure by the second expansion valve 162 to form a low-temperature and low-pressure refrigerant liquid. The low-temperature and low-pressure refrigerant exchanges heat in the first heat exchanger 13 and absorbs heat through the first heat exchanger 13. The refrigerant after absorbing heat evaporates into gas and flows into the gas-liquid separator 17 through the four-way valve 18 to filter out droplets. The filtered refrigerant gas returns to the compressor 11 from the air intake port 112 to continue the heating cycle.

[0049] The working state of the economizer 15 can be determined based on the on / off state of the first expansion valve 161. When the first expansion valve 161 is open, the economizer 15 is in the working state. When the first expansion valve 161 is closed, the economizer 15 is in the closed state.

[0050] In a specific embodiment, the first control valve 41 is configured to adjust its opening and closing in response to the opening and closing signals of the first expansion valve 161 and the pressure or temperature signal of the supply gas pipeline 50. Based on the pressure or temperature signal of the supply gas pipeline 50, the pressure value of the refrigerant gas output by the economizer 15 to the supply gas pipeline 50 can be determined. This converts the operating status of the economizer 15 into a tangible numerical value, facilitating logical analysis and automated regulation within the air conditioning system 100. In a specific embodiment, the first expansion valve 161 or the second expansion valve 162 can be configured as an electronic expansion valve, or a combination of a thermal expansion valve and a solenoid valve can be used instead.

[0051] In a specific embodiment, the pressure signal of the supply air pipeline 50 can be obtained by a pressure sensor, or a temperature signal can be obtained by a temperature sensor, and the pressure of the refrigerant in the supply air pipeline 50 can be converted based on the value of the temperature signal. (The temperature sensor and the pressure sensor are collectively referred to as sensors below.) Furthermore, a sensor can be installed on the supply air pipeline 50; or a sensor can be installed on the pipeline between the suction port of the compressor 11 and the outlet of the gas-liquid separator 17, and the supply air pressure can be calculated based on the suction pressure. Alternatively, during cooling, a sensor can be installed at the inlet of the second heat exchanger 14, and the pressure of the supply air pipeline 50 can be converted. During heating, a sensor can be installed at the inlet of the first heat exchanger 13, and the pressure of the supply air pipeline 50 can be converted. Alternatively, a sensor can be installed at the inlet of the economizer 15, and the evaporation pressure or evaporation temperature of the economizer 15 can be obtained, and the pressure of the supply air pipeline 50 can be converted. The various conversion methods involved are well known in the art and are not described in detail here.

[0052] Specifically, the air conditioning system 100 further includes a controller, which is connected to the first control valve 41 . The controller adjusts the opening and closing of the first control valve 41 according to the on / off state of the first expansion valve 161 .

[0053] In a specific embodiment, when the first expansion valve 161 is closed, the economizer 15 is not working, and the first control valve 41 is configured to open in response to the closing signal of the economizer 15 to disconnect the second branch 213, promote the flow of refrigerant oil to the first branch 212, and return to the compressor 11 from the suction port 112, thereby avoiding oil shock in the compressor 11.

[0054] In a specific embodiment, when the first expansion valve 161 is open, the economizer 15 is in operation, the supply air line 50 is set to a limited refrigerant pressure P, and the actual pressure in the supply air line 50 is P1. When P1 ≤ P, the first control valve 41 is configured to close in response to a signal indicating the actual pressure; if P1 > P, the first control valve 41 is configured to open in response to the signal indicating the actual pressure. In this manner, the actual pressure is compared with the limited pressure to accurately adjust the operating state of the first control valve 41. Specifically, when P1 ≤ P, indicating that the refrigerant gas pressure output by the economizer 15 does not exceed the limited pressure, the first control valve 41 closes, disconnecting the first branch 212 and promoting the flow of refrigerant oil to the second branch 213 and back to the compressor 11 from the supply air port 113, thereby reducing the power consumption of the compressor 11. When P1>P, it indicates that the refrigerant gas pressure output by the economizer 15 is greater than the limit pressure. At this time, the first control valve 41 opens to disconnect the second branch 213, promotes the flow of refrigeration oil to the first branch 212, and returns to the compressor 11 from the suction port 112 to avoid overload of the compressor 11.

[0055] In another specific embodiment, when first expansion valve 161 is open, economizer 15 is in operation, a refrigerant temperature limit T is set in supply air line 50, and the actual temperature of supply air line 50 is T1. When T1 ≤ T, first control valve 41 is configured to close in response to a signal indicating the actual temperature; if T1 > T, first control valve 41 is configured to open in response to the signal indicating the actual temperature. In this manner, the actual temperature is compared with the limit pressure to accurately adjust the operating state of first control valve 41. The specific effect is similar to the aforementioned embodiment in which the first control valve 41 is adjusted based on the comparison between the actual pressure and the limit pressure, and will not be further described here.

[0056] In a preferred embodiment, the main line 211, the first branch line 212 and the second branch line 213 together form the first oil return line 21; Figures 1 to 5 As shown, the oil return circuit 20 also includes a second oil return pipeline 22 and an oil return main pipeline 23. The inlet of the main pipeline 211 is connected to the oil return port of the oil separator 12 through the oil return main pipeline 23. The second oil return pipeline 22 is connected to the oil return main pipeline 23. The second oil return pipeline 22 and the main pipeline 211 are arranged in parallel. The second oil return pipeline 22 is connected to the intake port 112; the second control valve 42 is connected to the second oil return pipeline 22, and the second control valve 42 is configured to adjust the opening and closing in response to the frequency change of the compressor 11.

[0057] In this way, when the frequency of the compressor 11 is high, the oil discharge rate of the compressor 11 is also high, and the flow rate of the refrigerant oil increases. The provision of the second return oil pipeline 22 can increase the flow rate of the refrigerant oil return, and prevent the refrigerant oil from accumulating too much in the oil separator 12, causing a lack of oil in the compressor 11. The refrigerant oil first enters the return oil main pipe 23 from the return oil port, and is then diverted by the return oil main pipe 23 into the first return oil pipeline 21 and the second return oil pipeline 22. The oil is returned together through the two return oil pipelines, thereby speeding up the oil return efficiency. When the frequency of the compressor 11 is low, the second return oil pipeline 22 can also be disconnected by closing the second control valve 42, so that the refrigerant oil can be continuously and stably returned from the first return oil pipeline 21, and the refrigerant gas can be prevented from leaking from the return oil port due to excessive oil return.

[0058] Furthermore, the controller is also connected to the compressor 11 and the second control valve 42. After receiving the frequency signal of the compressor 11, the controller can adjust the opening and closing of the second control valve 42 accordingly. For example, the second control valve 42 can be a solenoid valve.

[0059] In a further embodiment, the frequency of the compressor 11 is F; the high frequency range of the compressor 11 is set to be above F1, the low frequency range of the compressor 11 is set to be below F1, and the adjustment difference is △n, △n≥0.

[0060] When F≥F1+△n, it indicates that the frequency of the compressor 11 is high, the corresponding oil discharge rate of the compressor 11 is also high, and the flow rate of the refrigerant oil is large. The second control valve 42 is configured to open in response to the compressor 11 being in a high-frequency state, that is, the controller adjusts the second control valve 42 to open, and the first return oil pipeline 21 and the second return oil pipeline 22 jointly transport the refrigerant oil back to the compressor 11, thereby improving the oil return efficiency of the refrigerant oil.

[0061] When F≤F1-△n, it indicates that the frequency of the compressor 11 is low, and the corresponding oil discharge rate of the compressor 11 is also low, and the flow rate of the refrigerant oil is small. The second control valve 42 is configured to close in response to the compressor 11 being in a low-frequency state, that is, the controller adjusts the second control valve 42 to close, and only the refrigerant oil needs to be transported through the first return oil pipeline 21. When the refrigerant gas pressure output by the economizer 15 is lower than the rated pressure, all the refrigerant oil can be returned to the compressor 11 from the air supply port 113 to ensure the output flow rate of the refrigerant.

[0062] The adjustment difference Δn is set to perform adjustment more accurately during actual operation to avoid the second control valve 42 from becoming unstable in its open and closed state when F=F1.

[0063] like Figures 1 to 5 As shown, in a further embodiment, a second throttle member 32 is provided on the second oil return line 22, and the second throttle member 32 is located between the second control valve 42 and the air intake port 112 to limit the flow of the refrigerant oil on the second oil return line 22 so that the refrigerant oil can continue to flow in the second oil return line 22.

[0064] In a specific embodiment, the first throttling member 31 is configured as a first capillary tube, and the second throttling member 32 is configured as a second capillary tube. The diameters of the first capillary tube and the second capillary tube are relatively small to limit the flow of the refrigeration oil.

[0065] Furthermore, the length of the second capillary tube is h, and the length of the first capillary tube is L, where h = (1 to 3) L. This arrangement allows the length of the second capillary tube to be greater than that of the first capillary tube, and the throttling effect of the second capillary tube is greater, and the restriction effect on the flow of the refrigerant oil is stronger, so that more refrigerant oil flows to the first return oil pipeline 21. When the refrigerant gas pressure output by the economizer 15 is less than the rated pressure, the flow rate of the refrigerant oil returning to the air supply port 113 is increased, thereby reducing interference with the refrigerant temperature. Of course, the length of the second capillary tube cannot be too long to ensure that the refrigerant oil can continue to circulate. For example, h = L, 2L or 3L.

[0066] More specifically, the inner diameter of the second capillary tube is d, and the inner diameter of the first capillary tube is D, where d = (0.3 to 1) D. This arrangement allows the inner diameter of the second capillary tube to be smaller than that of the first capillary tube, resulting in a greater throttling effect of the second capillary tube and a stronger restriction on the flow of the refrigerant oil, so that more refrigerant oil flows to the first return oil line 21. When the refrigerant gas pressure output by the economizer 15 is lower than the rated pressure, the flow rate of the refrigerant oil returning to the air supply port 113 is increased, thereby reducing interference with the refrigerant temperature. Of course, the inner diameter of the second capillary tube cannot be too small to ensure that the refrigerant oil can continue to circulate. For example, d = 0.3D, 0.5D or 1D.

[0067] like Figure 3 and Figure 4 As shown, in some embodiments, the outlet of the first branch 212 and / or the outlet of the second oil return line 22 is connected to the gas-liquid separator 17. After passing through the gas-liquid separator 17, the refrigerant oil flows back to the compressor 11 from the air intake 112, which can buffer the flow of the refrigerant oil.

[0068] like Figures 1 to 4 As shown, in a specific embodiment, a one-way valve 43 is provided on the second branch 213 or the air supply line 50 to prevent the refrigerant gas in the air supply line 50 from flowing into the gas-liquid separator 17 through the oil return circuit 20. Furthermore, when the one-way valve 43 is provided on the air supply line 50, the one-way valve 43 is positioned closer to the air supply port 113, which helps to isolate vibrations at the air supply port 113 and promote stable flow of the refrigerant oil.

[0069] like Figure 5 As shown, in more embodiments, a third throttle member 33 is provided on the second branch 213. The third throttle member 33 can limit the refrigerant in the air supply pipeline 50 from flowing into the gas-liquid separator 17 through the oil return circuit 20. In the first oil return pipeline 21, the refrigerant oil passes through the first throttle member 31 and the third throttle member 33 in sequence. Since the space in the pipeline between the first throttle member 31 and the second throttle member 32 is larger than the space in the first throttle member 31 and the third throttle member 33, respectively, the refrigerant oil flows from the first throttle member 31 into the pipeline between the first throttle member 31 and the third throttle member 33. This part of the pipeline space can serve as a temporary storage space. When the refrigerant oil in this part of the pipeline space is full, the refrigerant oil overflows from the third throttle member 33 and continues to flow to the air supply port 113.

[0070] like Figure 2 As shown, in more embodiments, a fourth throttling member 34 is provided on the first branch 212, and the fourth throttling member 34 is connected between the first control valve 41 and the air intake 112 to limit the flow of the refrigerant oil in the first branch 212 and promote continuous and stable return of the refrigerant oil. The effect of the fourth throttling member 34 is similar to that of the third throttling member 33 and will not be repeated here.

[0071] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of patent protection for the present application shall be determined by the appended claims.

Claims

1. An air conditioning system, characterized in that: include: A compressor (11), an oil separator (12) and an economizer (15), wherein the compressor (11) has an exhaust port (111), an air intake port (112) and an air supply port (113) arranged at intervals, the exhaust port (111) is communicated with the inlet of the oil separator (12), and the first flow channel (151) of the economizer (15) is communicated with the air supply port (113); The air conditioning system further comprises an oil return circuit (20), the oil return circuit (20) comprising a main line (211), a first branch line (212) and a second branch line (213), the inlet of the main line (211) being in communication with the oil return port of the oil separator (12), the first branch line (212) being in communication between the outlet of the main line (211) and the air intake port (112), the second branch line (213) being in communication between the outlet of the main line (211) and the air supply port (113), the first branch line (212) and the second branch line (213) being arranged in parallel, and the first flow channel (151) and the second branch line (213) being arranged in parallel; A first throttling member (31) is provided between the inlet and outlet of the main line (211), and a first control valve (41) is provided on the first branch line (212). The first control valve (41) is configured to adjust opening and closing in response to the working state of the economizer (15).

2. The air conditioning system according to claim 1, characterized in that The air conditioning system further comprises an air supply pipeline (50), the first flow channel (151) being in communication with the air supply port (113) via the air supply pipeline (50), and the second branch channel (213) being in communication with the air supply port (113) via the air supply pipeline (50); The air conditioning system further comprises a main circuit (10), the economizer (15) comprises a second flow channel (152), the economizer (15) is connected to the main circuit (10) via the second flow channel (152), the first flow channel (151) and the second flow channel (152) are arranged in parallel, and the first flow channel (151) can be connected to the main circuit (10) via a first expansion valve (161); The first control valve (41) is configured to adjust opening and closing in response to an opening and closing signal of the first expansion valve (161) and a pressure signal or a temperature signal of the air supply pipeline (50).

3. The air conditioning system according to claim 2, characterized in that When the first expansion valve (161) is closed, the first control valve (41) is configured to open in response to a closing signal of the economizer (15); When the first expansion valve (161) is opened, the air supply pipeline (50) is provided with a limited refrigerant pressure P, and the actual pressure of the air supply pipeline (50) is P1; when P1≤P, the first control valve (41) is configured to close in response to a signal of the actual pressure; if P1>P, the first control valve (41) is configured to open in response to a signal of the actual pressure; or, When the first expansion valve (161) is opened, the air supply pipeline (50) is provided with a limited temperature T of the refrigerant, and the actual temperature of the air supply pipeline (50) is T1; when T1≤T, the first control valve (41) is configured to close in response to a signal of the actual temperature; if T1>T, the first control valve (41) is configured to open in response to a signal of the actual temperature.

4. The air conditioning system according to claim 2, characterized in that The oil return circuit (20) further comprises a second oil return pipeline (22) and an oil return main pipeline (23); the inlet of the main pipeline (211) is connected to the oil return port of the oil separator (12) through the oil return main pipeline (23); the second oil return pipeline (22) is connected to the oil return main pipeline (23); the second oil return pipeline (22) and the main pipeline (211) are arranged in parallel; the second oil return pipeline (22) is connected to the air intake port (112); A second control valve (42) is connected to the second oil return line (22), and the second control valve (42) is configured to adjust opening and closing in response to frequency changes of the compressor (11).

5. The air conditioning system according to claim 4, characterized in that The frequency of the compressor (11) is F; the high frequency range of the compressor (11) is set to be above F1, and the low frequency range of the compressor (11) is set to be below F1, and the adjustment difference is △n, △n≥0; When F≥F1+Δn, the second control valve (42) is configured to open in response to the compressor (11) being in a high frequency state; When F≤F1-Δn, the second control valve (42) is configured to close in response to the compressor (11) being in a low-frequency state.

6. The air conditioning system according to claim 4, characterized in that A second throttle element (32) is provided on the second oil return pipeline (22), and the second throttle element (32) is located between the second control valve (42) and the air intake port (112).

7. The air conditioning system according to claim 6, characterized in that The first throttling member (31) is configured as a first capillary tube, and the second throttling member (32) is configured as a second capillary tube; The length of the second capillary is h, the length of the first capillary is L, h=(1-3)L; and / or the inner diameter of the second capillary is d, the inner diameter of the first capillary is D, d=(0.3-1)D.

8. The air conditioning system according to claim 4, characterized in that The main circuit (10) further includes a gas-liquid separator (17), the outlet of the gas-liquid separator (17) being in communication with the air intake (112); The outlet of the first branch (212) and / or the outlet of the second oil return pipeline (22) are connected to the gas-liquid separator (17).

9. The air conditioning system according to claim 2, characterized in that A one-way valve (43) is provided on the second branch (213) or the air supply pipeline (50); or a third throttling element (33) is provided on the second branch (213).

10. The air conditioning system according to claim 1, wherein: A fourth throttling element (34) is provided on the first branch (212), and the fourth throttling element (34) is connected between the first control valve (41) and the air intake (112).

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