Air conditioning system and control method

Abstract

The invention relates to the technical field of air conditioners, and provides an air conditioning system and a control method.The air conditioning system comprises a compressor, a four-way valve, an indoor heat exchanger, an outdoor heat exchanger, an auxiliary throttling element, a main throttling element and a liquid storage unit, and the auxiliary throttling element is arranged on a refrigerant pipeline between the four-way valve and the indoor heat exchanger; the main throttling element is arranged on a refrigerant pipeline between the indoor heat exchanger and the outdoor heat exchanger; an inlet of the liquid storage unit is connected to a refrigerant pipeline between the main throttling element and the indoor heat exchanger, and an outlet of the liquid storage unit is connected to a refrigerant pipeline between the auxiliary throttling element and the indoor heat exchanger; effective storage of liquid refrigerants left in an indoor heat exchanger and a corresponding pipeline in a heating mode is achieved. And in the refrigeration preparation stage when the system is switched from the heating mode to the refrigeration mode, the liquid refrigerant stored in the liquid storage unit is released to the indoor heat exchanger through the system pressure difference, the starting time of the refrigeration mode is shortened, and the defrosting efficiency is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, and in particular to an air conditioning system and control method. Background Technology

[0002] In cold climates, during heating operation, the outdoor heat exchanger of an air conditioning system, acting as an evaporator, gradually forms a frost layer due to the condensation and freezing of water vapor in the air. This leads to decreased heat exchange efficiency, increased air resistance, and consequently affects the system's heating capacity and operational stability. To maintain normal heating performance, the system needs to switch to defrost mode. During defrost, a four-way valve switches the refrigerant flow, putting the system into a refrigeration cycle. At this point, the indoor unit, which was originally a condenser, becomes an evaporator, while the outdoor unit, which was originally an evaporator, becomes a condenser. The high-temperature, high-pressure refrigerant discharged from the compressor melts the frost layer on the outdoor side.

[0003] However, when the air conditioning system switches from heating mode to defrost mode (cooling mode), the refrigeration cycle is established relatively slowly, resulting in low defrosting efficiency. Summary of the Invention

[0004] This invention provides an air conditioning system and control method to solve the problem of low defrosting efficiency in the prior art. By setting up a liquid storage unit, the system can actively store and release liquid refrigerant, effectively shortening the start-up time of the cooling mode and thus improving defrosting efficiency.

[0005] This invention provides an air conditioning system, comprising: A compressor, a four-way valve, an indoor heat exchanger, and an outdoor heat exchanger are connected to form a refrigerant circulation loop. A secondary throttling device is installed in the refrigerant pipeline between the four-way valve and the indoor heat exchanger; The main throttling device is installed in the refrigerant pipeline between the indoor heat exchanger and the outdoor heat exchanger; A liquid storage unit has its inlet connected to the refrigerant pipeline between the main throttling device and the indoor heat exchanger, and its outlet connected to the refrigerant pipeline between the secondary throttling device and the indoor heat exchanger. The liquid storage unit stores liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device during heating mode, and releases the stored liquid refrigerant to the indoor heat exchanger during the cooling preparation phase. The cooling preparation phase is the stage during which the opening degree of the main throttling device is reduced to its minimum during the switching process from heating mode to cooling mode of the air conditioning system.

[0006] According to an air conditioning system provided by the present invention, the liquid storage unit includes multiple liquid storage tanks connected in parallel. The inlets of the multiple liquid storage tanks are connected to a refrigerant pipeline between the main throttling device and the indoor heat exchanger via a pressure-reducing pipeline. The outlets of the multiple liquid storage tanks are connected to a refrigerant pipeline between the secondary throttling device and the indoor heat exchanger via a pressure-boosting pipeline. A first control valve is provided at the inlet of each liquid storage tank, and a second control valve is provided at the outlet of each liquid storage tank.

[0007] According to an air conditioning system provided by the present invention, at least two of the liquid storage tanks have different capacities.

[0008] According to an air conditioning system provided by the present invention, the liquid storage tank is provided with a pressure relief valve and / or the liquid storage tank is provided with a level gauge.

[0009] According to an air conditioning system provided by the present invention, the secondary throttling device and / or the primary throttling device is an electronic expansion valve, and / or... The first control valve and / or the second control valve are solenoid valves.

[0010] The present invention also provides a control method for an air conditioning system, comprising: If it is determined that there is frost on the outdoor heat exchanger, reduce the compressor frequency and decrease the opening of the auxiliary throttling device and the main throttling device; The liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device is stored in the liquid storage unit; During the process of switching the air conditioning system from heating mode to cooling mode, the opening of the main throttling device is reduced to the minimum opening, and the liquid refrigerant in the liquid storage unit is released into the indoor heat exchanger. The frequency of the compressor is increased to the target frequency, and the opening degree of the auxiliary throttling device and the main throttling device are increased to the corresponding target opening degree.

[0011] According to a control method for an air conditioning system provided by the present invention, the liquid storage unit includes a first liquid storage tank and a second liquid storage tank, wherein the capacity of the first liquid storage tank is greater than the capacity of the second liquid storage tank, and the step of storing liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device into the liquid storage unit includes: The liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device is stored in the first liquid storage tank. When the amount of refrigerant in the first liquid storage tank reaches a first preset capacity or the pressure in the first liquid storage tank reaches a first preset pressure, the liquid refrigerant is stored in the second liquid storage tank.

[0012] According to a control method for an air conditioning system provided by the present invention, the step of releasing the liquid refrigerant in the liquid storage unit to the indoor heat exchanger includes: The liquid refrigerant in the second storage tank is released into the indoor heat exchanger; With the liquid refrigerant in the second storage tank emptied, the liquid refrigerant in the first storage tank is released into the indoor heat exchanger.

[0013] According to a control method for an air conditioning system provided by the present invention, the step of releasing the liquid refrigerant in the liquid storage unit to the indoor heat exchanger includes: Determine the current pressure on the low-pressure side of the air conditioning system; The target refrigerant release amount is determined based on the difference between the current pressure and the preset target pressure; The liquid storage unit is controlled to release the target amount of liquid refrigerant to the indoor heat exchanger.

[0014] According to a control method for an air conditioning system provided by the present invention, the method further includes: In response to the air conditioner shutdown command, the air conditioning system is controlled to operate in cooling mode, and the opening degree of the secondary throttling device is controlled to be at the minimum opening degree and the opening degree of the main throttling device is controlled to be at the maximum opening degree.

[0015] The air conditioning system provided by this invention, by adding a liquid storage unit and connecting its inlet to the refrigerant pipeline between the main throttling device and the indoor heat exchanger, and its outlet to the refrigerant pipeline between the secondary throttling device and the indoor heat exchanger, achieves effective storage of liquid refrigerant remaining in the indoor heat exchanger and corresponding pipelines during heating mode; and during the cooling preparation stage when the system switches from heating mode to cooling mode, by reducing the opening of the main throttling device to the minimum opening, the liquid refrigerant stored in the liquid storage unit is quickly released and returned to the indoor heat exchanger by utilizing the system pressure difference, significantly shortening the start-up time of cooling mode, enabling the system to enter the high-efficiency cooling cycle more quickly, accelerating the defrosting speed of the outdoor heat exchanger, and effectively improving defrosting efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the air conditioning system provided by the present invention.

[0018] Figure 2This is one of the flowcharts illustrating the control method for the air conditioning system provided by the present invention.

[0019] Figure 3 This is the second flowchart illustrating the control method of the air conditioning system provided by the present invention.

[0020] Figure 4 This is the third flowchart illustrating the control method for the air conditioning system provided by the present invention.

[0021] Figure label: 10. Compressor; 20. Four-way valve; 30. Indoor heat exchanger; 40. Outdoor heat exchanger; 50. Secondary throttling device; 60. Main throttling device; 70. Liquid storage unit; 71. First liquid storage tank; 72. Second liquid storage tank; 73. Pressure reducing pipeline; 74. Pressure increasing pipeline; 75. First control valve; 76. Second control valve. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present 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. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0025] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0026] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0027] An embodiment of the first aspect of the present invention provides an air conditioning system, such as Figure 1 As shown, the air conditioning system includes a compressor 10, a four-way valve 20, an indoor heat exchanger 30, an outdoor heat exchanger 40, a secondary throttling device 50, a main throttling device 60, and a liquid storage unit 70.

[0028] The compressor 10, four-way valve 20, indoor heat exchanger 30 and outdoor heat exchanger 40 are connected to form a refrigerant circulation loop. The secondary throttling device 50 is installed in the refrigerant pipeline between the four-way valve 20 and the indoor heat exchanger 30, and the main throttling device 60 is installed in the refrigerant pipeline between the indoor heat exchanger 30 and the outdoor heat exchanger 40.

[0029] The inlet of the liquid storage unit 70 is connected to the refrigerant pipeline between the main throttling device 60 and the indoor heat exchanger 30, and the outlet of the liquid storage unit 70 is connected to the refrigerant pipeline between the secondary throttling device 50 and the indoor heat exchanger 30. The liquid storage unit 70 is used to store liquid refrigerant in the indoor heat exchanger 30 and the refrigerant pipeline between the indoor heat exchanger 30 and the main throttling device 60 in heating mode, and to release the stored liquid refrigerant to the indoor heat exchanger 30 in the cooling preparation stage; wherein, the cooling preparation stage is the stage in which the opening degree of the main throttling device 60 is reduced to the minimum opening degree during the process of the air conditioning system switching from heating mode to cooling mode.

[0030] It is understood that the outlet and inlet of compressor 10 are connected to two ports of four-way valve 20, and the other two ports of four-way valve 20 are connected to indoor heat exchanger 30 and outdoor heat exchanger 40, respectively, thus forming a refrigerant circulation loop together with compressor 10, indoor heat exchanger 30 and outdoor heat exchanger 40. In terms of refrigerant piping arrangement, auxiliary throttling device 50 is installed in the refrigerant piping between four-way valve 20 and indoor heat exchanger 30, i.e., on the gas pipe of indoor heat exchanger 30, to regulate the refrigerant flow rate entering indoor heat exchanger 30; main throttling device 60 is installed in the refrigerant piping between indoor heat exchanger 30 and outdoor heat exchanger 40 to control the throttling process of refrigerant during cooling or heating operation; the inlet of liquid receiver unit 70 is connected to the refrigerant piping between main throttling device 60 and indoor heat exchanger 30, and its outlet... An auxiliary liquid storage path is formed on the refrigerant pipeline connected between the secondary throttling device 50 and the indoor heat exchanger 30, parallel to the main circulation path. When the system is in heating mode, the liquid storage unit 70 can collect and store the liquid refrigerant remaining inside the indoor heat exchanger 30 and in the pipeline flowing from the indoor heat exchanger 30 to the main throttling device 60, preventing liquid refrigerant from entering the compressor 10 and causing liquid slugging. When the air conditioning system switches from heating mode to cooling mode, it enters the cooling preparation stage. At this time, the control system adjusts the opening of the main throttling device 60 to the minimum opening, reducing the pipeline flow capacity, causing the liquid refrigerant stored in the liquid storage unit 70 to be released under the action of pressure difference and re-enter the indoor heat exchanger 30, quickly establishing a suitable refrigerant distribution state for cooling operation, and improving the system stability and operating efficiency during the mode switching process.

[0031] The air conditioning system provided in this embodiment of the invention, by adding a liquid storage unit 70, with its inlet connected to the refrigerant pipeline between the main throttling device 60 and the indoor heat exchanger 30, and its outlet connected to the refrigerant pipeline between the secondary throttling device 50 and the indoor heat exchanger 30, achieves effective storage of liquid refrigerant remaining in the indoor heat exchanger 30 and the corresponding pipelines during heating mode; and during the cooling preparation stage when the system switches from heating mode to cooling mode, by reducing the opening of the main throttling device 60 to its minimum opening, the liquid refrigerant stored in the liquid storage unit 70 is quickly released and returned to the indoor heat exchanger 30 using the system pressure difference, achieving rapid pre-distribution of refrigerant and significantly shortening the start-up time of cooling mode; especially during defrosting, it enables the system to enter the high-efficiency cooling cycle more quickly, accelerates the defrosting speed of the outdoor heat exchanger 40, and effectively improves defrosting efficiency.

[0032] It should be noted that in the existing technology, during the heating operation phase, the indoor heat exchanger 30 works as a condenser, and the refrigerant continuously condenses and gradually accumulates into a liquid state inside it. Especially under low load or low temperature conditions, the refrigerant flow rate is reduced and evaporation is insufficient, resulting in a large amount of liquid refrigerant remaining in the heat exchanger and connecting pipes. When the system switches to defrost mode (i.e., from heating to cooling cycle), the four-way valve 20 reverses the direction of refrigerant flow, and the liquid refrigerant originally accumulated on the indoor side quickly flows back under pressure, which is very easy to be sucked into the compressor 10, causing liquid slugging and seriously threatening the safe operation of the compressor 10. At the same time, since the indoor heat exchanger 30 needs to be used as an evaporator at this time, but a large amount of liquid refrigerant still remains inside it, it cannot immediately and effectively absorb heat and evaporate, resulting in limited evaporation capacity, low heat exchange efficiency, slow establishment of the cooling cycle, and thus prolonging the defrost start-up time and reducing the overall defrost efficiency. This application, by setting up a liquid storage unit 70, enables the active collection and storage of excess liquid refrigerant on the indoor side during heating mode. This not only reduces the risk of liquid slugging the compressor 10 during mode switching, but also, during the refrigeration preparation stage before defrosting, by controlling the opening of the main throttling device 60 to be reduced to a minimum, utilizes the system pressure difference to orderly release the liquid refrigerant stored in the liquid storage unit 70 and prioritize its delivery to the indoor heat exchanger 30. This allows the refrigerant to quickly participate in the evaporation and heat absorption process at the initial stage of the refrigeration cycle, significantly improving the initial heat exchange capacity of the evaporator, effectively shortening the establishment time of the refrigeration mode, thereby accelerating the defrosting response speed and significantly improving defrosting efficiency.

[0033] According to an embodiment of the present invention, the secondary throttling device 50 adopts an electronic expansion valve; of course, the main throttling device 60 can also adopt an electronic expansion valve.

[0034] In one embodiment of the present invention, the liquid storage unit 70 includes a plurality of liquid storage tanks connected in parallel. The inlets of the plurality of liquid storage tanks are connected to the refrigerant pipeline between the main throttling device 60 and the indoor heat exchanger 30 via a pressure-reducing pipeline 73. The outlets of the plurality of liquid storage tanks are connected to the refrigerant pipeline between the secondary throttling device 50 and the indoor heat exchanger 30 via a pressure-boosting pipeline 74. A first control valve 75 is provided at the inlet of the liquid storage tank, and a second control valve 76 is provided at the outlet of the liquid storage tank.

[0035] Understandably, the liquid storage unit 70 includes multiple parallel liquid storage tanks to enhance the flexibility and controllability of refrigerant storage and release; the inlets of the multiple liquid storage tanks are connected to the refrigerant pipeline between the main throttling device 60 and the indoor heat exchanger 30 via a common or branched pressure-reducing pipeline 73. This connection point is located on the high-pressure side of the system (when the system is in heating mode), facilitating the reception of liquid refrigerant from the outlet of the indoor heat exchanger 30 in heating mode; the outlets of the multiple liquid storage tanks are connected to the secondary throttling device 50 and the indoor heat exchanger 30 via a common or branched pressure-boosting pipeline 74. The refrigerant piping between heat exchangers 30 is located on the low-pressure side of the system (when the system is in cooling mode), allowing the liquid refrigerant in the storage tank to flow smoothly back to the indoor heat exchanger 30 under pressure differential during the cooling preparation phase. A first control valve 75 is installed at the inlet of each storage tank to control the flow of liquid refrigerant into the storage tank, thereby managing the liquid storage process. A second control valve 76 is installed at the outlet of each storage tank to control the release of the stored liquid refrigerant to the indoor heat exchanger 30, thereby enabling on-demand step-by-step or coordinated release.

[0036] It should be noted that the liquid storage unit 70 is configured with multiple liquid storage tanks in parallel and each has its own independent control valve. The system can flexibly start and stop different liquid storage tanks according to the operating load, refrigerant accumulation or defrosting requirements, thereby improving the precision of refrigerant regulation and further optimizing the stability and efficiency during mode switching.

[0037] Optionally, at least two of the storage tanks may have different capacities.

[0038] Understandably, at least two of the storage tanks have different capacities, meaning the multiple parallel storage tanks have differentiated volume designs. This allows the storage unit 70 to perform tiered storage and on-demand release based on the amount of liquid refrigerant accumulated in the system under different operating conditions. For example, when the heating load is low and the amount of liquid refrigerant generated is small, only the smaller capacity storage tank can be used for storage, avoiding the refrigerant from being dispersed and stagnant in the large capacity tank, which could lead to insufficient release or slow response. Conversely, when there is a large amount of refrigerant accumulation under high heating load or low temperature conditions, the larger capacity storage tanks can be used simultaneously to ensure sufficient storage space and prevent overflow or backflow abnormalities. Thus, by setting up storage tanks of different capacities and combining them with their respective independent first control valves 75 and second control valves 76 for on / off control, the overall space utilization and structural layout flexibility are optimized.

[0039] Optionally, the first control valve 75 can be a solenoid valve; of course, the second control valve 76 can also be a solenoid valve.

[0040] In this embodiment, both the first control valve 75 and the second control valve 76 are two-position, two-way solenoid valves. It should be noted that the first control valve 75 and the second control valve 76 cannot be opened simultaneously to prevent a short circuit between high and low pressure.

[0041] Optionally, the storage tank is equipped with a pressure relief valve, which automatically opens when the internal pressure of the storage tank rises abnormally, releasing the overpressurized refrigerant to a safe area, thereby preventing the risk of container deformation or rupture due to excessive pressure.

[0042] It should be noted that the pressure relief valve is usually set to open at a pressure slightly higher than the normal operating pressure of the system to ensure that it remains sealed during normal operation and only activates under abnormal conditions. This does not affect the normal functioning of the liquid storage and provides a reliable passive safety protection mechanism for the system.

[0043] Optionally, the storage tank is equipped with a level gauge.

[0044] For example, a level gauge is installed on the side wall of the storage tank or connected to the storage tank via a connecting pipe to monitor the amount or level of liquid refrigerant stored in the tank in real time.

[0045] Understandably, during the refrigerant storage phase, when the amount of refrigerant in the storage tank reaches the preset maximum value, the level gauge will trigger a signal to remind or control the first control valve 75 to close, preventing pressure increases and potential risks caused by excessive storage. At the same time, during the refrigerant release phase, the level gauge monitors the liquid level drop to ensure that the second control valve 76 is closed in time when the refrigerant drops to the preset minimum value, preventing gaseous refrigerant from accidentally entering and affecting the system's circulation efficiency.

[0046] Based on the air conditioning system provided in any of the above embodiments, a second aspect of the present invention proposes a control method for the air conditioning system, such as... Figure 2 As shown, the control method includes the following steps: Step 100: If the outdoor heat exchanger is frosted, reduce the compressor frequency and decrease the opening of the secondary and main throttling devices.

[0047] Understandably, when the air conditioning system is in heating mode, it determines the frosting condition of the outdoor heat exchanger. If there is frosting on the outdoor heat exchanger, the system starts the defrosting preparation program. By reducing the operating frequency of the compressor and simultaneously reducing the opening of the secondary and main throttling devices, the system gradually exits the high-efficiency heating state and enters the low-load operation mode, so as to smoothly transition and reduce the impact of refrigerant flow.

[0048] Step 200: Store the liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device into the liquid storage unit.

[0049] It is understandable that the liquid storage unit is used to collect and store the liquid refrigerant accumulated in the indoor heat exchanger and the refrigerant pipeline between it and the main throttling device, which is still in the heating cycle, in order to avoid the liquid refrigerant residue affecting the safety of subsequent mode switching.

[0050] Step 300: During the process of switching the air conditioning system from heating mode to cooling mode, the opening of the main throttling device is reduced to the minimum opening, and the liquid refrigerant in the liquid storage unit is released to the indoor heat exchanger.

[0051] Understandably, when the air conditioning system switches from heating mode to cooling mode, the opening of the main throttling device is further reduced to the minimum opening, which is the cooling preparation stage. This creates a pressure difference in the system pipeline that is conducive to the release of refrigerant from the liquid storage unit. The indoor heat exchanger becomes a low-pressure evaporator, which causes the liquid refrigerant stored in the liquid storage unit to be released quickly and flow back to the indoor heat exchanger, realizing the pre-distribution of refrigerant and improving the initial heat exchange capacity of the evaporator.

[0052] Step 400: Increase the frequency of the compressor to the target frequency, and increase the opening of the secondary throttling device and the main throttling device to the corresponding target opening.

[0053] Understandably, after the liquid refrigerant stored in the liquid storage unit is released, the system enters a stable cooling and defrosting phase. The compressor frequency is gradually increased to the preset target frequency, and the opening of the secondary and main throttling devices is adjusted to the corresponding target opening. This allows the system to quickly establish an efficient cooling cycle, accelerate the defrosting speed of the outdoor heat exchanger, thereby shortening the defrosting time and improving defrosting efficiency and overall system stability.

[0054] In one embodiment of the present invention, the liquid storage unit includes a first liquid storage tank and a second liquid storage tank, wherein the capacity of the first liquid storage tank is greater than the capacity of the second liquid storage tank, such as... Figure 3 As shown, step 200 may specifically include the following steps: Step 210: Store the liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device into the first liquid storage tank.

[0055] Step 220: When the amount of refrigerant in the first liquid storage tank reaches the first preset capacity or the pressure in the first liquid storage tank reaches the first preset pressure, the liquid refrigerant is stored in the second liquid storage tank.

[0056] It is understood that the liquid storage unit in this embodiment includes two parallel liquid storage tanks, namely a first liquid storage tank and a second liquid storage tank. The capacity of the first liquid storage tank is larger than that of the second liquid storage tank to achieve hierarchical management and optimized utilization of refrigerant storage. Correspondingly, the liquid refrigerant storage process is as follows: liquid refrigerant existing in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device in the heating mode is preferentially guided to the larger capacity first liquid storage tank for storage; when the amount of liquid refrigerant in the first liquid storage tank reaches a first preset capacity, or when its internal pressure rises to a first preset pressure, it indicates that the first liquid storage tank has approached its safe or effective storage limit. At this time, the storage path is switched, and the subsequent liquid refrigerant is transferred to the second liquid storage tank by opening the first control valve at the inlet of the second liquid storage tank.

[0057] It should be noted that the liquid storage unit uses first and second liquid storage tanks of different capacities to achieve tiered storage. This not only improves the adaptability of the liquid storage unit to different operating conditions and avoids overloading of a single tank, but also effectively utilizes the small-capacity tank for fine adjustment, ensuring the safety and stability of the refrigerant recovery process, and providing a good foundation for the rapid start-up of subsequent refrigeration modes and the improvement of defrosting efficiency.

[0058] In one embodiment of the present invention, step 300, releasing the liquid refrigerant in the storage unit to the indoor heat exchanger, may specifically include the following steps: Step 310: Release the liquid refrigerant in the second storage tank into the indoor heat exchanger.

[0059] Step 320: With the liquid refrigerant in the second storage tank emptied, release the liquid refrigerant in the first storage tank into the indoor heat exchanger.

[0060] Understandably, when the air conditioning system switches from heating mode to cooling mode and the main throttling device opening decreases to its minimum, the system first opens the second control valve at the outlet of the second liquid receiver tank. This releases the liquid refrigerant stored in the smaller second liquid receiver tank and delivers it to the indoor heat exchanger. Utilizing its smaller volume, the system achieves a rapid response, allowing the refrigerant to quickly participate in the evaporation and heat absorption process, thus accelerating the establishment of the cooling cycle. Once the system detects that the liquid refrigerant in the second liquid receiver tank is essentially emptied, it then opens the second control valve at the outlet of the first liquid receiver tank, releasing the liquid refrigerant stored in the larger first liquid receiver tank to the indoor heat exchanger to meet the greater refrigerant demand. In this way, the liquid refrigerant is released in stages, effectively ensuring a rapid response at the initial stage of cooling mode startup and improving the smoothness of system mode switching.

[0061] In one embodiment of the present invention, step 300, releasing the liquid refrigerant in the storage unit to the indoor heat exchanger, may specifically include the following steps: Step 330: Determine the current pressure on the low-pressure side of the air conditioning system.

[0062] Step 340: Determine the target refrigerant release amount based on the difference between the current pressure and the preset target pressure.

[0063] Step 350: Control the liquid storage unit to release the target amount of liquid refrigerant to the indoor heat exchanger.

[0064] Understandably, when the air conditioning system switches from heating mode to cooling mode, the opening of the main throttling device is further reduced to its minimum, thereby creating a pressure differential condition in the system pipeline that is conducive to the release of refrigerant from the liquid storage unit. The current pressure on the low-pressure side of the air conditioning system is detected and determined by the low-pressure side pressure sensor, and real-time operating status parameters are obtained. The current pressure is compared with the preset target pressure, and the target amount of refrigerant to be released is determined based on the pressure difference between the two, thereby achieving precise refrigerant supply on demand. Subsequently, the control system opens the second control valve at the outlet of the second liquid storage tank and / or the first liquid storage tank in an orderly manner according to the calculated target refrigerant release amount, controlling the liquid storage unit to release the corresponding amount of liquid refrigerant to the indoor heat exchanger.

[0065] In one embodiment of the present invention, such as Figure 4 As shown, the method further includes the following steps: Step 500: In response to the air conditioner shutdown command, control the air conditioning system to operate in cooling mode, and control the opening degree of the secondary throttling device to be at the minimum opening degree and the opening degree of the main throttling device to be at the maximum opening degree.

[0066] Understandably, in response to the air conditioner shutdown command, the control system first puts the air conditioning system into a pre-drainage operation mode before shutting down. This means that the air conditioning system continues to operate in cooling mode, while the opening of the secondary throttling device is adjusted to the minimum to limit the refrigerant flow capacity, and the opening of the main throttling device is adjusted to the maximum to reduce throttling resistance. Thus, under the action of the system operating pressure difference, the residual liquid refrigerant in the liquid tank is fully driven and migrated into the system's refrigerant circulation loop, achieving active refrigerant recovery.

[0067] In one specific embodiment of the present invention, such as Figure 1 As shown, The air conditioning system includes a compressor 10, a four-way valve 20, an indoor heat exchanger 30, an outdoor heat exchanger 40, a secondary throttling device 50, a main throttling device 60, and a liquid receiver 70.

[0068] The compressor 10, four-way valve 20, indoor heat exchanger 30 and outdoor heat exchanger 40 are connected to form a refrigerant circulation loop. The secondary throttling device 50 is installed in the refrigerant pipeline between the four-way valve 20 and the indoor heat exchanger 30, and the main throttling device 60 is installed in the refrigerant pipeline between the indoor heat exchanger 30 and the outdoor heat exchanger 40.

[0069] The liquid storage unit 70 includes a first liquid storage tank 71 and a second liquid storage tank 72 connected in parallel. The inlet of the first liquid storage tank 71 and the inlet of the second liquid storage tank 72 are connected to one end of a pressure-reducing pipeline 73. The other end of the pressure-reducing pipeline 73 is connected to the refrigerant pipeline between the main throttling device 60 and the indoor heat exchanger 30, that is, the other end of the pressure-reducing pipeline 73 is connected to the upstream side of the inlet of the main throttling device 60 (the outlet of the indoor heat exchanger 30). The outlet of the first liquid storage tank 71 and the outlet of the second liquid storage tank 72 are connected to one end of a pressure-boosting pipeline 74. The other end of the pressure-boosting pipeline 74 is connected to the refrigerant pipeline between the secondary throttling device 50 and the indoor heat exchanger 30, that is, the other end of the pressure-boosting pipeline 74 is connected to the upstream side of the inlet of the indoor heat exchanger 30 (the inlet of the indoor heat exchanger 30).

[0070] The first and second liquid storage tanks are high-pressure resistant containers equipped with level gauges. The capacity of the first liquid storage tank is greater than that of the second liquid storage tank. The first liquid storage tank serves as the main storage tank for refrigerant, while the second liquid storage tank serves as a backup or expansion tank.

[0071] The first control valve installed at the inlet of the first liquid storage tank is denoted as the first control valve A, and the second control valve installed at the outlet of the first liquid storage tank is denoted as the second control valve A; the first control valve installed at the inlet of the second liquid storage tank is denoted as the first control valve B, and the second control valve installed at the outlet of the second liquid storage tank is denoted as the second control valve B.

[0072] The specific control process of the air conditioning system in this embodiment is as follows: S1. When the air conditioning system is in heating mode, it determines the frosting condition of the outdoor heat exchanger. If there is frosting on the outdoor heat exchanger, it enters the defrosting preparation stage.

[0073] The frosting condition of the outdoor heat exchanger is determined by real-time monitoring of the coil temperature and the duration of sustained low temperatures. Specifically, temperature sensors located at key positions on the fins or coils of the outdoor heat exchanger collect coil temperature values. When the detected temperature is lower than a preset frosting temperature threshold (e.g., 0°C or a dynamic threshold corrected for ambient humidity), a timing mechanism is activated. If the coil temperature remains below this threshold for more than a preset duration (e.g., 5 minutes, 10 minutes, etc., depending on climate conditions and unit characteristics), it is determined that frosting has occurred on the outdoor heat exchanger.

[0074] The defrosting preparation stage involves reducing the compressor's operating frequency and simultaneously decreasing the opening of both the secondary and primary throttling devices, gradually transitioning the system from high-efficiency heating to a low-load operating mode. In this embodiment, the compressor is reduced to 50% of its rated heating frequency; the openings of the secondary and primary throttling devices can be reduced to their minimum. It should be noted that in other embodiments, the defrosting preparation stage may also involve shutting down the compressor and reducing the openings of the secondary and primary throttling devices to their minimum or closing them.

[0075] S2. Store the liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device into the liquid storage unit.

[0076] Specifically, the first control valve A is opened, and the liquid refrigerant accumulated in the indoor heat exchanger and liquid pipe is pushed into the first storage tank by utilizing the high pressure of the system at this time (heating cycle, the outdoor heat exchanger is the condenser) and the relatively stable pressure difference after frequency reduction. After the first storage tank is completed, the first control valve B is opened to store the liquid refrigerant accumulated in the indoor heat exchanger and liquid pipe in the second storage tank.

[0077] It should be noted that if the first control valve A and the first control valve B are kept open, and the first and second liquid storage tanks reach the set liquid levels, or the pressure on the low-pressure side of the system does not rise significantly (indicating that the migration has slowed down), then the storage of liquid refrigerant by the liquid storage unit is completed; after that, the first control valve A and the first control valve B are closed.

[0078] S3. During the process of switching the air conditioning system from heating mode to cooling mode, the opening of the main throttling device is reduced to the minimum opening, and the liquid refrigerant in the liquid storage unit is released to the indoor heat exchanger.

[0079] It is understandable that when the air conditioning system switches from heating mode to cooling mode, a pressure difference is created in the system pipeline that is conducive to the release of refrigerant by the liquid storage unit. The indoor heat exchanger becomes a low-pressure evaporator. The liquid storage pressure in the liquid storage tank (which is higher than the evaporation pressure) and the low-pressure suction of the evaporator that will soon be formed push the liquid refrigerant in the liquid storage tank into the indoor heat exchanger.

[0080] It should be noted that in this embodiment, the second control valve B is opened first to release the liquid refrigerant stored in the smaller second storage tank into the indoor heat exchanger. After the second storage tank is emptied, the second control valve A is opened to use the high pressure in the first storage tank to further propel the liquid refrigerant into the indoor heat exchanger, thereby completing the release of the liquid refrigerant from the second storage tank.

[0081] S4. Control the compressor frequency to increase to the target frequency, and control the opening degree of the auxiliary throttling device and the main throttling device to increase to the corresponding target opening degree.

[0082] Understandably, after the liquid refrigerant stored in the liquid storage unit is released, the system enters a stable cooling and defrosting phase, gradually increasing the compressor frequency to the preset target frequency, while adjusting the opening of the secondary and main throttling devices to the corresponding target opening.

[0083] It should be noted that the second control valve A and the second control valve B should be kept open until the first and second liquid receivers are completely emptied, or the high-pressure side pressure of the system begins to rise steadily (indicating that the refrigerant has begun to participate in the refrigerant circulation of the system). Then, the first control valve A and the first control valve B should be closed. Then the system enters the stable cooling and defrosting stage. At this time, the compressor frequency gradually increases to the preset target frequency, and the opening degree of the secondary throttling device and the main throttling device is adjusted to the maximum opening degree.

[0084] Embodiments of the present invention also provide a control device for an air conditioning system, the control device comprising the following modules: The first control module is used to reduce the compressor frequency and decrease the opening of the secondary and main throttling devices when the outdoor heat exchanger is frosted.

[0085] The storage module is used to store the liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device into the liquid storage unit.

[0086] The second control module is used to reduce the opening of the main throttling device to the minimum opening during the process of switching the air conditioning system from heating mode to cooling mode, so as to release the liquid refrigerant in the liquid storage unit to the indoor heat exchanger.

[0087] The third control module is used to control the compressor frequency to increase to the target frequency, and to control the opening degree of the auxiliary throttling device and the main throttling device to increase to the corresponding target opening degree.

[0088] Embodiments of the present invention also propose an electronic device, which may include: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. The processor can call logical instructions in the memory to execute a control method for an air conditioning system. The method includes: when it is determined that there is frost on the outdoor heat exchanger, reducing the compressor frequency and reducing the opening of the secondary throttling device and the main throttling device; storing the liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device in a liquid storage unit; during the process of switching the air conditioning system from heating mode to cooling mode, controlling the opening of the main throttling device to decrease to the minimum opening, and releasing the liquid refrigerant in the liquid storage unit to the indoor heat exchanger; controlling the compressor frequency to increase to a target frequency, and controlling the opening of the secondary throttling device and the main throttling device to increase to the corresponding target opening.

[0089] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0090] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the control method of the air conditioning system provided by the above methods. The method includes: when it is determined that there is frost on the outdoor heat exchanger, reducing the frequency of the compressor and reducing the opening of the secondary throttling device and the main throttling device; storing the liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device in a liquid storage unit; during the process of switching the air conditioning system from heating mode to cooling mode, controlling the opening of the main throttling device to reduce to the minimum opening and releasing the liquid refrigerant in the liquid storage unit to the indoor heat exchanger; controlling the frequency of the compressor to increase to the target frequency, and controlling the opening of the secondary throttling device and the main throttling device to increase to the corresponding target opening.

[0091] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements a control method for an air conditioning system provided by the above methods. The method includes: determining that frost has formed on the outdoor heat exchanger, reducing the compressor frequency and decreasing the opening of the secondary throttling device and the main throttling device; storing liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device in a liquid storage unit; during the process of switching the air conditioning system from heating mode to cooling mode, controlling the opening of the main throttling device to decrease to a minimum opening, and releasing the liquid refrigerant in the liquid storage unit to the indoor heat exchanger; controlling the compressor frequency to increase to a target frequency, and controlling the opening of the secondary throttling device and the main throttling device to increase to corresponding target openings.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An air conditioning system, characterized in that, include: A compressor, a four-way valve, an indoor heat exchanger, and an outdoor heat exchanger are connected to form a refrigerant circulation loop. A secondary throttling device is installed in the refrigerant pipeline between the four-way valve and the indoor heat exchanger; The main throttling device is installed in the refrigerant pipeline between the indoor heat exchanger and the outdoor heat exchanger; A liquid storage unit has its inlet connected to the refrigerant pipeline between the main throttling device and the indoor heat exchanger, and its outlet connected to the refrigerant pipeline between the secondary throttling device and the indoor heat exchanger. The liquid storage unit stores liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device during heating mode, and releases the stored liquid refrigerant to the indoor heat exchanger during the cooling preparation phase. The cooling preparation phase is the stage during which the opening degree of the main throttling device is reduced to its minimum during the switching process from heating mode to cooling mode of the air conditioning system.

2. The air conditioning system according to claim 1, characterized in that, The liquid storage unit includes multiple liquid storage tanks connected in parallel. The inlets of the multiple liquid storage tanks are connected to the refrigerant pipeline between the main throttling device and the indoor heat exchanger via pressure-reducing pipelines. The outlets of the multiple liquid storage tanks are connected to the refrigerant pipeline between the secondary throttling device and the indoor heat exchanger via pressure-boosting pipelines. A first control valve is provided at the inlet of each liquid storage tank, and a second control valve is provided at the outlet of each liquid storage tank.

3. The air conditioning system according to claim 2, characterized in that, At least two of the storage tanks have different capacities.

4. The air conditioning system according to claim 2, characterized in that, The liquid storage tank is equipped with a pressure relief valve and / or a liquid level gauge.

5. The air conditioning system according to claim 2, characterized in that, The secondary throttling device and / or the primary throttling device are electronic expansion valves, and / or, The first control valve and / or the second control valve are solenoid valves.

6. A control method for an air conditioning system according to any one of claims 1 to 5, characterized in that, include: If it is determined that there is frost on the outdoor heat exchanger, reduce the compressor frequency and decrease the opening of the auxiliary throttling device and the main throttling device; The liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device is stored in the liquid storage unit. During the process of switching the air conditioning system from heating mode to cooling mode, the opening of the main throttling device is reduced to the minimum opening, and the liquid refrigerant in the liquid storage unit is released into the indoor heat exchanger. The frequency of the compressor is increased to the target frequency, and the opening degree of the auxiliary throttling device and the main throttling device are increased to the corresponding target opening degree.

7. The control method for an air conditioning system according to claim 6, characterized in that, The liquid storage unit includes a first liquid storage tank and a second liquid storage tank, wherein the capacity of the first liquid storage tank is greater than the capacity of the second liquid storage tank. The step of storing the liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device into the liquid storage unit includes: The liquid refrigerant in the indoor heat exchanger and the refrigerant pipeline between the indoor heat exchanger and the main throttling device is stored in the first liquid storage tank. When the amount of refrigerant in the first liquid storage tank reaches a first preset capacity or the pressure in the first liquid storage tank reaches a first preset pressure, the liquid refrigerant is stored in the second liquid storage tank.

8. The control method for an air conditioning system according to claim 7, characterized in that, The step of releasing the liquid refrigerant in the storage unit to the indoor heat exchanger includes: The liquid refrigerant in the second storage tank is released into the indoor heat exchanger; With the liquid refrigerant in the second storage tank emptied, the liquid refrigerant in the first storage tank is released into the indoor heat exchanger.

9. The control method for an air conditioning system according to any one of claims 6 to 8, characterized in that, The step of releasing the liquid refrigerant in the storage unit to the indoor heat exchanger includes: Determine the current pressure on the low-pressure side of the air conditioning system; The target refrigerant release amount is determined based on the difference between the current pressure and the preset target pressure; The liquid storage unit is controlled to release the target amount of liquid refrigerant to the indoor heat exchanger.

10. The control method for an air conditioning system according to claim 9, characterized in that, The method further includes: In response to the air conditioner shutdown command, the air conditioning system is controlled to operate in cooling mode, and the opening degree of the secondary throttling device is controlled to be at the minimum opening degree and the opening degree of the main throttling device is controlled to be at the maximum opening degree.

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