Dual-compressor air conditioning system and control method thereof

Abstract

Embodiments of the present application provide a dual-compressor air conditioning system and a control method thereof. The dual-compressor air conditioning system comprises a first branch, a second branch and a switching unit. The first branch is sequentially provided with a first control check valve, a first compressor and a second control check valve. The second branch is sequentially provided with a third control check valve, a second compressor and a fourth control check valve. The switching unit is arranged between the first branch and the second branch. The switching unit comprises a first switching branch, a second switching branch and a switching valve. The control method is applied to the dual-compressor air conditioning system. The present application can switch the connection mode of the dual compressor, improve the load adaptability and working efficiency.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and more specifically, to a dual-compressor air conditioning system and its control method. Background Technology

[0002] Currently, automotive refrigeration systems primarily use a single, large-displacement compressor. When operating conditions change, the system mainly adapts by adjusting the compressor's speed and allocating cooling capacity to the battery or passenger compartment through control strategies. However, this configuration of refrigeration systems is gradually revealing its drawbacks, including the following defects: (1) There is an optimal efficiency point for the compressor in any refrigeration system, and there is a common law that when the actual operating pressure ratio deviates from the design value, the internal leakage will increase sharply and the volumetric efficiency will decrease significantly as the pressure ratio increases.

[0003] (2) The automotive refrigeration system is often under partial load conditions, and there is often a phenomenon of "overpowering the engine". This usually needs to be solved by adjusting the compressor speed. The isentropic efficiency of the compressor is also related to the speed. There is an optimal operating point. When the speed changes, its efficiency will also change.

[0004] (3) The "cooling rush" problem exists in multiple temperature zones. Under extreme conditions, such as when the vehicle is charged with a high current (e.g., 4C-5C or even higher rates), the battery generates extremely high heat (up to 10-15kW). At this time, the thermal management system needs to do its best to cool the battery. In this case, the car's cooling system will prioritize cooling the battery, and the cooling effect of the cabin will be greatly reduced, resulting in poor cabin comfort when charging in the summer. If the cabin is prioritized, it will lead to charging current limiting and a decrease in charging speed.

[0005] (4) A single compressor system in a vehicle typically needs to cover multiple temperature zones, which are mutually constrained. For example, the evaporation temperatures required by a multi-evaporator system are inconsistent (e.g., the evaporation temperature required by the battery and the vehicle refrigerator is -10℃, while the evaporation temperature required by the cabin is 1℃). Since multiple evaporators share the low-pressure suction port of the compressor, the evaporation pressure and temperature of each evaporator are similar, making it impossible to obtain different evaporation pressures. Furthermore, a single compressor also has the problem of difficulty in oil return under extremely low load.

[0006] (5) No safety redundancy backup. If a single compressor fails (such as compressor jamming or protection failure), the car's refrigeration system will completely collapse and will be unable to cool. Summary of the Invention

[0007] The present invention aims to provide a dual-compressor air conditioning system and its control method, which can switch the connection mode of the dual compressors to improve load adaptability and working efficiency.

[0008] The embodiments of the present invention can be implemented as follows: An embodiment of the present invention provides a dual-compressor air conditioning system, comprising: The first branch is provided with a first control check valve, a first compressor and a second control check valve in sequence. The second branch is provided with a third control check valve, a second compressor and a fourth control check valve in sequence. A switching unit is disposed between the first branch and the second branch, and the switching unit includes a first switching branch, a second switching branch, and a switching valve; The first switching branch and the second switching branch are intersected and connected in the middle. One end of the first switching branch is connected to the first branch at the position between the first control check valve and the first compressor. The other end of the first switching branch is connected to the second branch at the position between the fourth control check valve and the second compressor. One end of the second switching branch is connected to the first branch at the position between the second control check valve and the first compressor. The other end of the second switching branch is connected to the second branch at the position between the third control check valve and the second compressor. The switching valve is located at the intersection of the first switching branch and the second switching branch, and the switching valve is configured to control both the first switching branch and the second switching branch to be in a closed state, or to control one of the first switching branch and the second switching branch to be in a connected state.

[0009] Optionally, the dual-compressor air conditioning system further includes a distribution branch, one end of which is connected upstream of the first control check valve on the first branch, and the other end of which is connected upstream of the third control check valve on the second branch. A distribution valve is provided on the distribution branch to control the on / off state of the distribution branch.

[0010] Optionally, the dual-compressor air conditioning system further includes an oil supply branch pipe, the two ends of which are respectively connected to the bottom of the oil storage of the first compressor and the bottom of the oil storage of the second compressor, and an oil equalization valve is provided on the oil supply branch pipe for controlling the opening and closing of the oil supply branch pipe.

[0011] Optionally, the switching valve is a plug valve.

[0012] Optionally, the switching valve is provided with a gas replenishment port, which is used to replenish and introduce refrigerant vapor.

[0013] Optionally, the downstream of the second control check valve of the first branch and the downstream of the fourth control check valve of the second branch are connected to the same exhaust port.

[0014] Embodiments of the present invention also provide a control method for a dual-compressor air conditioning system, applied to the aforementioned dual-compressor air conditioning system, comprising: Close the first control check valve, open the second control check valve, open the third control check valve, close the fourth control check valve, open the switching valve and switch it to a state that connects the first switching branch, so that the second compressor and the first compressor sequentially form a two-stage compression path.

[0015] Optionally, the control method further includes: opening the first control check valve, closing the second control check valve, closing the third control check valve, opening the fourth control check valve, opening the switching valve and switching it to a state that connects the second switching branch, so that the first compressor and the second compressor sequentially form a two-stage compression path.

[0016] Optionally, the control method further includes: closing the first control check valve, the second control check valve, the third control check valve, and the fourth control check valve, and closing the switching valve, so that the first branch and the second branch form two independent compression paths, and the first compressor and the second compressor respectively adapt to the evaporator connected upstream of the first branch and the second branch.

[0017] Optionally, the control method further includes: opening a distribution valve to connect the distribution branch, wherein the distribution branch adjusts the refrigerant flow rate distributed to the first compressor and the second compressor according to the refrigerant pressure difference at its two ends.

[0018] The beneficial effects of the dual-compressor air conditioning system and its control method provided in this invention include: The dual-compressor air conditioning system includes a first branch, a second branch, and a switching unit. The first branch is sequentially equipped with a first control check valve, a first compressor, and a second control check valve. The second branch is sequentially equipped with a third control check valve, a second compressor, and a fourth control check valve. The switching unit is located between the first and second branches and includes a first switching branch, a second switching branch, and a switching valve. The first and second switching branches intersect and connect in the middle. One end of the first switching branch connects to a position on the first branch between the first control check valve and the first compressor, and the other end connects to a position on the second branch between the fourth control check valve and the second compressor. One end of the second switching branch connects to a position on the first branch between the second control check valve and the first compressor, and the other end connects to a position on the second branch between the third control check valve and the second compressor. The switching valve is located at the intersection of the first and second switching branches and is configured to control both the first and second switching branches to be in a closed state, or one of the first and second switching branches to be in a connected state.

[0019] This dual-compressor air conditioning system can change the connection mode of the first and second compressors by selectively switching the control check valves on the first and second branches and controlling the on / off state of the switching valve in the switching unit. This allows the first and second compressors to operate independently or form a two-stage compression path. In this way, only one compressor can be activated under low load, while both compressors can be activated under high load. Furthermore, when the two compressors operate independently, they can match the different evaporator requirements for multiple evaporation pressures and temperatures. This improves the load adaptability of the air conditioning system and avoids a single compressor operating in a low-efficiency range for extended periods, thus improving compressor efficiency.

[0020] The control method for the dual-compressor air conditioning system is applied to the aforementioned dual-compressor air conditioning system, and it has all the functions of a dual-compressor air conditioning system. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the frame structure of the dual-compressor air conditioning system provided in this embodiment; Figure 2A schematic diagram of the refrigerant flow direction in the first control mode of the dual-compressor air conditioning system provided in this embodiment; Figure 3 A schematic diagram of the refrigerant flow direction in the second control mode of the dual-compressor air conditioning system provided in this embodiment; Figure 4 A schematic diagram of the refrigerant flow direction in the third control mode of the dual-compressor air conditioning system provided in this embodiment; Figure 5 This is a schematic diagram of the refrigerant flow direction in the fourth control mode of the dual-compressor air conditioning system provided in this embodiment.

[0023] Icons: 100 - First branch; 110 - First control check valve; 120 - First compressor; 130 - Second control check valve; 200 - Second branch; 210 - Third control check valve; 220 - Second compressor; 230 - Fourth control check valve; 300 - Switching unit; 310 - First switching branch; 320 - Second switching branch; 330 - Switching valve; 331 - Air supply port; 400 - Distribution branch; 410 - Distribution valve; 500 - Oil supply branch pipe; 510 - Oil equalization valve; 600 - Exhaust port. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0028] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0029] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0030] The following is combined Figures 1 to 5 The dual-compressor air conditioning system and its control method provided in this embodiment are described in detail.

[0031] Please refer to Figure 1 An embodiment of the present invention provides a dual-compressor air conditioning system, which includes a first branch 100, a second branch 200, and a switching unit 300.

[0032] A first control check valve 110, a first compressor 120, and a second control check valve 130 are sequentially arranged on the first branch 100. A third control check valve 210, a second compressor 220, and a fourth control check valve 230 are sequentially arranged on the second branch 200. A switching unit 300 is disposed between the first branch 100 and the second branch 200, and the switching unit 300 includes a first switching branch 310, a second switching branch 320, and a switching valve 330.

[0033] The first switching branch 310 and the second switching branch 320 are intersected and connected in the middle. One end of the first switching branch 310 is connected to the first branch 100 at a position between the first control check valve 110 and the first compressor 120, and the other end of the first switching branch 310 is connected to the second branch 200 at a position between the fourth control check valve 230 and the second compressor 220. One end of the second switching branch 320 is connected to the first branch 100 at a position between the second control check valve 130 and the first compressor 120, and the other end of the second switching branch 320 is connected to the second branch 200 at a position between the third control check valve 210 and the second compressor 220. The switching valve 330 is located at the intersection of the first switching branch 310 and the second switching branch 320, and the switching valve 330 is configured to control both the first switching branch 310 and the second switching branch 320 to be in a closed state, or to control one of the first switching branch 310 and the second switching branch 320 to be in a connected state.

[0034] Specifically, the first control check valve 110 is used to control the opening and closing of the one-way flow path of refrigerant from the suction port of the first branch 100 to the inlet of the first compressor 120; the second control check valve 130 is used to control the opening and closing of the one-way flow path of refrigerant from the outlet of the first compressor 120 to the discharge port 600 of the first branch 100; the third control check valve 210 is used to control the opening and closing of the one-way flow path of refrigerant from the suction port of the second branch 200 to the inlet of the second compressor 220; and the fourth control check valve 230 is used to control the opening and closing of the one-way flow path of refrigerant from the outlet of the second compressor 220 to the discharge port 600 of the second branch 200.

[0035] When the switching valve 330 is closed, both the first switching branch 310 and the second switching branch 320 are in the off state, allowing the first compressor 120 and the second compressor 220 to operate independently on the first branch 100 and the second branch 200, respectively. When the switching valve 330 is open, the first switching branch 310 may be in the connected state and the second switching branch 320 may be in the off state, allowing the inlet of the first compressor 120 to be connected to the outlet of the second compressor 220, thus enabling the second compressor 220 and the first compressor 120 to form a two-stage compression path in sequence; alternatively, the second switching branch 320 may be in the connected state and the first switching branch 310 may be in the off state, allowing the inlet of the second compressor 220 to be connected to the outlet of the first compressor 120, thus enabling the first compressor 120 and the second compressor 220 to form a two-stage compression path in sequence.

[0036] With this configuration, the dual-compressor air conditioning system can selectively switch the control check valves on the first branch 100 and the second branch 200, as well as the on / off state of the switching valve 330 in the control switching unit 300, to change the connection mode of the first compressor 120 and the second compressor 220. This allows the first compressor 120 and the second compressor 220 to operate independently or form a two-stage compression path. In this way, only one compressor can be activated under low load, while both compressors can be activated under high load. Furthermore, when the two compressors operate independently, they can match the different evaporator requirements for multiple evaporation pressures and temperatures. This improves the load adaptability of the air conditioning system and avoids a single compressor operating in a low-efficiency range for extended periods, thus improving compressor efficiency.

[0037] It should be noted that the first compressor 120 and the second compressor 220 can be two compressors of the same displacement, or a combination of one large and one small displacement compressor, depending on the usage scenario. If the two compressors are of the same displacement, they can serve as backups for each other, preventing a complete collapse of the air conditioning system due to compressor failure. They can operate alternately during operation, avoiding prolonged operation of a single compressor and extending its lifespan. If the two compressors are a combination of one large and one small displacement compressor, the large displacement compressor can cover most operating conditions, improving efficiency. When the large compressor's load is insufficient, the small compressor can be activated as an auxiliary. The first compressor 120 and the second compressor 220 can be integrated into a single compressor housing.

[0038] In this embodiment, the dual-compressor air conditioning system further includes a distribution branch 400. One end of the distribution branch 400 is connected to the upstream position of the first control check valve 110 on the first branch 100, and the other end of the distribution branch 400 is connected to the upstream position of the third control check valve 210 on the second branch 200. A distribution valve 410 is provided on the distribution branch 400, which is used to control the on / off state of the distribution branch 400.

[0039] Specifically, the two ends of the distribution branch pipe are connected to the suction ports of the first branch 100 and the second branch 200, respectively, and the distribution valve 410 can control the opening and closing of the distribution branch 400. When the distribution valve 410 is open, and there is a refrigerant pressure difference between the suction ports of the first branch 100 and the second branch 200, the distribution branch pipe can adjust the refrigerant flow rate distributed to the first compressor 120 and the second compressor 220.

[0040] It should be noted that the refrigerant in the distribution branch 400 can only flow in one direction at a time. The flow direction is determined by the pressure difference between the suction port of the first branch 100 and the suction port of the second branch 200. The flow direction is always from the high-pressure end to the low-pressure end.

[0041] Furthermore, the distribution valve 410 is a regulating valve, which can adjust the distribution ratio of refrigerant on the first branch 100 and the second branch 200 by adjusting the opening size.

[0042] In this embodiment, the dual-compressor air conditioning system further includes an oil supply branch pipe 500, the two ends of which are connected to the bottom of the oil storage of the first compressor 120 and the bottom of the oil storage of the second compressor 220, respectively. An oil equalization valve 510 is provided on the oil supply branch pipe 500, which is used to control the opening and closing of the oil supply branch pipe 500.

[0043] Specifically, when either the first compressor 120 or the second compressor 220 is running, the oil equalization valve 510 is closed to ensure normal operation of the compressor. When both the first compressor 120 and the second compressor 220 are stopped, the oil equalization valve 510 opens; after opening, the internal pressure of the air conditioning system is balanced, and the bottoms of the oil reservoirs of the two compressors are connected, forming a communicating vessel with the same oil level, thereby avoiding uneven distribution of lubricating oil inside the two compressors.

[0044] In this embodiment, the switching valve 330 is a plug valve. Specifically, the switching valve 330 is a three-position four-way plug valve.

[0045] In this embodiment, the switching valve 330 is provided with a gas replenishment port 331, which is used to replenish and introduce refrigerant vapor.

[0046] Specifically, when the first compressor 120 and the second compressor 220 form a two-stage compression path, the switching valve 330 can introduce refrigerant vapor at intermediate pressure through the gas injection port 331, allowing it to flow to the next stage compressor, thus achieving the gas injection enthalpy enhancement function. When the air conditioning system does not require gas injection enthalpy enhancement, the gas injection port 331 can be sealed with a plug.

[0047] In this embodiment, the downstream of the second control check valve 130 of the first branch 100 and the downstream of the fourth control check valve 230 of the second branch 200 are connected to the same exhaust port 600. That is, the first branch 100 and the second branch 200 are each provided with their own intake ports at the intake end, and share a common exhaust port 600 at the exhaust end.

[0048] Embodiments of the present invention also provide a control method for a dual-compressor air conditioning system, applied to the aforementioned dual-compressor air conditioning system. This control method includes at least four control modes, which are described in detail below. Please refer to... Figures 2 to 4 The arrows indicate the direction of refrigerant flow when the system is operating.

[0049] Please refer to Figure 2 The first control mode is as follows: the first control check valve 110, the second control check valve 130, the third control check valve 210 and the fourth control check valve 230 are closed, and the switching valve 330 is closed, so that the first branch 100 and the second branch 200 form two independent compression paths. The first compressor 120 and the second compressor 220 are adapted to operate according to the evaporators connected upstream of the first branch 100 and the second branch 200, respectively.

[0050] Specifically, in the first control mode, the first compressor 120 and the second compressor 220 are connected in parallel. If a distribution branch 400 is provided, the distribution valve 410 is closed. The outlets of the first compressor 120 and the second compressor 220 flow to the same high-pressure exhaust port 600. The first compressor 120 and the second compressor 220 independently share the refrigerant flow at the suction port of their respective branches. That is, in the first control mode, the suction ports of the first branch 100 and the second branch 200 can be connected to different evaporators. The first compressor 120 and the second compressor 220 can achieve different evaporation pressures and temperatures to meet the needs of different evaporation pressure and temperature scenarios, such as an evaporation pressure of 200 kPaA for a vehicle refrigerator and a passenger compartment evaporation pressure requirement of 400 kPaA (with R134a refrigerant). This solves the problem that a single compressor cannot handle different evaporation pressures simultaneously.

[0051] Compared to existing new energy vehicles that use traditional single-compressor air conditioning systems, where the cabin and battery often compete for refrigerant during fast charging in summer, the dual-compressor air conditioning system of this invention allows the first branch 100 and the second branch 200 to each be equipped with an expansion valve in the first control mode, and the evaporation pressure and temperature of the two can be controlled independently.

[0052] Please refer to Figure 3 The second control mode is as follows: the distribution valve 410 is opened to connect the distribution branch 400. The distribution branch 400 adjusts the refrigerant flow rate distributed to the first compressor 120 and the second compressor 220 according to the refrigerant pressure difference at both ends.

[0053] Specifically, the second control mode is for a dual-compressor air conditioning system equipped with a distribution branch 400 and a distribution valve 410. In the second control mode, the first compressor 120 and the second compressor 220 are connected in parallel, the distribution valve 410 is open, and the first compressor 120 and the second compressor 220 can adjust the load sharing through the distribution valve 410 to avoid one compressor being overloaded while the other compressor is idle or underloaded.

[0054] It should be noted that the refrigerant in the distribution branch pipe can only flow in one direction at a time. The specific flow direction is determined by the pressure difference between the suction port of the first branch 100 and the suction port of the second branch 200. The flow direction is always from the high-pressure end to the low-pressure end.

[0055] When the first compressor 120 and the second compressor 220 are connected in parallel, the two compressors can operate alternately, avoiding the long-term operation of a single compressor and extending the service life of the compressor; it can also improve safety redundancy, so that if one compressor fails, the other compressor can still retain some cooling capacity, preventing the entire air conditioning system from collapsing.

[0056] Please refer to Figure 4 The third control mode is as follows: close the first control check valve 110, open the second control check valve 130, open the third control check valve 210, close the fourth control check valve 230, open the switching valve 330 and switch it to the state that connects the first switching branch 310, so that the second compressor 220 and the first compressor 120 form a two-stage compression path in sequence.

[0057] Specifically, in the third control mode, the first control check valve 110 is closed, cutting off the one-way flow path of refrigerant from the suction port of the first branch 100 to the inlet of the first compressor 120; the second control check valve 130 is opened, connecting the one-way flow path of refrigerant from the outlet of the first compressor 120 to the discharge port 600 of the first branch 100; the third control check valve 210 is opened, connecting the one-way flow path of refrigerant from the suction port of the second branch 200 to the inlet of the second compressor 220; the fourth control check valve 230 is closed, cutting off the one-way flow path of refrigerant from the outlet of the second compressor 220 to the discharge port 600 of the second branch 200; the switching valve 330 is opened and switched to a state where the first switching branch 310 is connected, while the second switching branch 320 is closed, so that the second compressor 220 and the first compressor 120 are in series and form a two-stage compression path. At this time, the second compressor is the low-pressure stage, and the first compressor 120 is the high-pressure stage, and the two work together to meet the high load demand. Specifically, the switching valve 330 can be rotated to such a position. Figure 4 The position at 45°.

[0058] Please refer to Figure 5 The fourth control mode is as follows: the first control check valve 110 is opened, the second control check valve 130 is closed, the third control check valve 210 is closed, the fourth control check valve 230 is opened, and the switching valve 330 is opened and switched to the state that connects the second switching branch 320, so that the first compressor 120 and the second compressor 220 form a two-stage compression path in sequence.

[0059] Specifically, in the fourth control mode, the first control check valve 110 is opened, connecting the refrigerant flow path from the suction port of the first branch 100 to the inlet of the first compressor 120; the second control check valve 130 is closed, shutting off the refrigerant flow path from the outlet of the first compressor 120 to the discharge port 600 of the first branch 100; the third control check valve 210 is closed, shutting off the refrigerant flow path from the suction port of the second branch 200 to the inlet of the second compressor 220; the fourth control check valve 230 is opened, connecting the refrigerant flow path from the outlet of the second compressor 220 to the discharge port 600 of the second branch 200; the switching valve 330 is opened and switched to a state that connects the second switching branch 320, while the first switching branch 310 is closed, so that the first compressor 120 and the second compressor 220 are in series and form a two-stage compression path. At this time, the first compressor is the low-pressure stage, and the second compressor 220 is the high-pressure stage, and the two work together to meet the high load demand. Specifically, the switching valve 330 can be rotated to such a position. Figure 5 The position at 135°.

[0060] It should be noted that in the third and fourth control modes, the distribution valve 410 can be opened or closed, depending on the actual needs. When the distribution valve 410 is open, refrigerant from the suction port of another branch can be introduced through the distribution branch 400 to supplement the system and meet the high-load operation requirements of the air conditioning system.

[0061] The third and fourth control modes broaden the operating range of the air conditioning system. Specifically, when the ambient temperature is too high, the air conditioning system needs to increase the condensing pressure to raise the condensing temperature and widen the heat transfer temperature difference with the ambient temperature. If a single compressor is used in this situation, the pressure ratio (the ratio of the exhaust port pressure to the intake port pressure) is large, resulting in reduced volumetric efficiency of the compressor. In the third or fourth control mode of this invention, the two compressors are connected in series, effectively dividing a high-pressure-ratio compressor into two low-pressure-ratio compressors, thus improving efficiency. Similarly, when the ambient temperature is too low, a single compressor will also have a large pressure ratio. By connecting two compressors in series, a two-stage compression is achieved, reducing the pressure ratio of a single compressor, improving efficiency, reducing reliance on the PTC heater, and improving the vehicle's winter range. This improves the fault tolerance of the air conditioning system (meeting the redundancy requirements of autonomous driving or high-reliability vehicles) and provides ultimate parking comfort.

[0062] The beneficial effects of the dual-compressor air conditioning system and its control method provided in this invention include: (1) This invention can solve the problem of "overpowering a small vehicle". The most obvious difference between a single large-displacement compressor and a system with two small-displacement compressors is that the refrigeration system of a single large-displacement compressor is in a non-full-load state most of the time. Simply put, a single large-displacement compressor is like "overpowering a small vehicle", while the dual-compressor air conditioning system of this invention can start only one compressor under low load and start both compressors under high load.

[0063] (2) The present invention can solve the problem that a single compressor cannot meet the requirements of multiple evaporators for multiple evaporation pressures and temperatures. The dual-compressor air conditioning system of the present invention can use two compressors to match different evaporation pressures and temperatures, which can avoid the single compressor from operating in a low-efficiency range for a long time in order to accommodate the low-temperature requirements, thereby significantly reducing energy consumption and improving the vehicle's range.

[0064] (3) The present invention can solve the problem of single compressor deviating from economic speed and economic operating conditions, resulting in reduced efficiency. The dual compressor air conditioning system of the present invention can flexibly allocate load and improve system efficiency.

[0065] (4) The dual-compressor air conditioning system of the present invention has safety redundancy. If a single compressor fails (such as a compressor jamming), the system will completely collapse and will be unable to cool. The present invention uses dual compressors, so if one compressor fails, the other compressor can take over in an emergency. Although it may not be able to support extreme conditions such as overcharging and full seating, it can at least ensure that the battery does not overheat, prevent thermal runaway and basic cooling of the driver's seat, and ensure that the vehicle can be safely driven to a repair shop, avoiding vehicle breakdown due to thermal management failure.

[0066] (5) The present invention can solve the problem of mutual migration and accumulation of lubricating oil in a dual compressor system. The two compressors operate alternately, and the oil equalization valve 510 is set to open when the machine stops, so that the oil level of the two compressors is the same, avoiding one compressor from being short of oil and the other from being too high in oil.

[0067] (6) Compared with the intermittent start and stop of a single large-displacement compressor, the dual-compressor air conditioning system of the present invention can achieve near-imperceptible thermal management by alternating between the two compressors.

[0068] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-compressor air conditioning system, characterized in that, include: The first branch (100) is provided with a first control check valve (110), a first compressor (120) and a second control check valve (130) in sequence. The second branch (200) is provided with a third control check valve (210), a second compressor (220) and a fourth control check valve (230) in sequence. A switching unit (300) is disposed between the first branch (100) and the second branch (200). The switching unit (300) includes a first switching branch (310), a second switching branch (320), and a switching valve (330). The first switching branch (310) and the second switching branch (320) are intersected and connected in the middle. One end of the first switching branch (310) is connected to the first branch (100) at the position between the first control check valve (110) and the first compressor (120). The other end of the first switching branch (310) is connected to the second branch (200) at the position between the fourth control check valve (230) and the second compressor (220). One end of the second switching branch (320) is connected to the first branch (100) at the position between the second control check valve (130) and the first compressor (120). The other end of the second switching branch (320) is connected to the second branch (200) at the position between the third control check valve (210) and the second compressor (220). The switching valve (330) is located at the intersection of the first switching branch (310) and the second switching branch (320), and the switching valve (330) is configured to control both the first switching branch (310) and the second switching branch (320) to be in a closed state, or to control one of the first switching branch (310) and the second switching branch (320) to be in a connected state.

2. The dual-compressor air conditioning system according to claim 1, characterized in that, The dual-compressor air conditioning system further includes a distribution branch (400), one end of which is connected to the upstream position of the first control check valve (110) on the first branch (100), and the other end of which is connected to the upstream position of the third control check valve (210) on the second branch (200). A distribution valve (410) is provided on the distribution branch (400) for controlling the on / off state of the distribution branch (400).

3. The dual-compressor air conditioning system according to claim 1, characterized in that, The dual-compressor air conditioning system also includes an oil supply branch pipe (500), the two ends of which are connected to the bottom of the oil storage of the first compressor (120) and the bottom of the oil storage of the second compressor (220), respectively. An oil equalization valve (510) is provided on the oil supply branch pipe (500), which is used to control the opening and closing of the oil supply branch pipe (500).

4. The dual-compressor air conditioning system according to claim 1, characterized in that, The switching valve (330) is a plug valve.

5. The dual-compressor air conditioning system according to claim 1, characterized in that, The switching valve (330) is provided with a gas replenishment port (331), which is used to replenish and introduce refrigerant vapor.

6. The dual-compressor air conditioning system according to claim 1, characterized in that, The downstream of the second control check valve (130) of the first branch (100) and the downstream of the fourth control check valve (230) of the second branch (200) are connected to the same exhaust port (600).

7. A control method for a dual-compressor air conditioning system, characterized in that, Applied to the dual-compressor air conditioning system as described in any one of claims 1 to 6, comprising: Close the first control check valve (110), open the second control check valve (130), open the third control check valve (210), close the fourth control check valve (230), open the switching valve (330) and switch it to the state that connects the first switching branch (310), so that the second compressor (220) and the first compressor (120) form a two-stage compression path in sequence.

8. The control method for a dual-compressor air conditioning system according to claim 7, characterized in that, The control method further includes: Open the first control check valve (110), close the second control check valve (130), close the third control check valve (210), open the fourth control check valve (230), open the switching valve (330) and switch it to the state that connects the second switching branch (320), so that the first compressor (120) and the second compressor (220) form a two-stage compression path in sequence.

9. The control method for a dual-compressor air conditioning system according to claim 7, characterized in that, The control method further includes: The first control check valve (110), the second control check valve (130), the third control check valve (210), and the fourth control check valve (230) are closed, and the switching valve (330) is closed, so that the first branch (100) and the second branch (200) form two independent compression paths. The first compressor (120) and the second compressor (220) are adapted to operate according to the evaporators connected upstream of the first branch (100) and the second branch (200), respectively.

10. The control method for a dual-compressor air conditioning system according to claim 9, characterized in that, The control method further includes: Open the distribution valve (410) to connect the distribution branch (400), and the distribution branch (400) adjusts the refrigerant flow rate distributed to the first compressor (120) and the second compressor (220) according to the refrigerant pressure difference at its two ends.

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