Active flow path switching valve, air conditioning system and control method

Abstract

The invention discloses an active flow path switching valve, an air conditioning system and a control method. The active flow path switching valve comprises a main valve assembly and a pilot valve assembly. The main valve assembly comprises a valve body, a piston dividing a driving cavity into two cavities, a sliding block in a switching cavity, a connecting rod and a reset mechanism. The pilot valve assembly is controlled by the electromagnetic driving mechanism; pressure distribution of the cavities on the two sides of the piston is changed by switching the gas circuit through the pilot valve, pressure difference is formed to drive the piston to overcome reset force to move, and then the sliding block is driven to change a flow path in the switching cavity. Compared with the prior art, active switching of flow paths is achieved, and it is ensured that the heat exchanger is always in an efficient and reliable flow direction state.

Description

Technical Field

[0001] This invention relates to the field of heating, ventilation and air conditioning equipment and fluid control components, and in particular to an active flow path switching valve, an air conditioning system and a control method. Background Technology

[0002] With the advancement of technology and the improvement of living standards, users have increasingly higher requirements for their living environment, and the application of air conditioning equipment is becoming more and more widespread. In particular, air conditioning systems using water systems are favored because of their advantages such as stable operation and precise temperature control.

[0003] On the water-fluorine heat exchange side, shell-and-tube heat exchangers or plate heat exchangers are currently the most commonly used. Taking shell-and-tube heat exchangers as an example, their heat exchange efficiency is significantly affected by the co-current and counter-current flow patterns. Typically, counter-current heat exchange efficiency is about 15% higher than co-current flow. However, conventional systems often cannot maintain counter-current heat exchange in both cooling and heating modes due to structural or control limitations. Forcing both modes to be maintained would lead to problems such as increased heat exchanger size and increased refrigerant charge. In addition, the oil return capacity of the heat exchanger is also affected by the flow direction. The oil return performance is usually better when the flow is from top to bottom than when it is from bottom to top. Frequent changes in flow direction are not conducive to the long-term reliable operation of the system.

[0004] Currently, to address the issues of bidirectional heat exchange efficiency and oil return, it is typically necessary to add complex valve assemblies to the system or sacrifice some energy efficiency. Existing technologies lack a low-cost, highly reliable solution for actively switching the refrigerant side flow direction and adapting to special operating conditions such as defrosting.

[0005] Therefore, how to provide a device that can actively switch flow paths to ensure that the heat exchanger is always in a state of high efficiency and reliable flow has become an urgent technical problem to be solved. Summary of the Invention

[0006] In view of the problem in the prior art that it is difficult to ensure that the heat exchanger is always in a state of high efficiency and reliable flow direction when the flow path is switched, the present invention proposes an active flow path switching valve, an air conditioning system and a control method.

[0007] The technical solution of this invention is to propose an active flow path switching valve, comprising:

[0008] A main valve assembly, the main valve assembly including a valve body having a drive chamber and a switching chamber, a piston dividing the drive chamber into a first chamber and a second chamber, a slider movably disposed in the switching chamber, a connecting rod connecting the piston and the slider, and a reset mechanism for applying a reset force to the piston;

[0009] A pilot valve assembly having an electromagnetic drive mechanism, a first inlet, a second inlet, a first outlet, and a second outlet, wherein the first outlet is connected to a first chamber, and the second outlet is connected to a second chamber;

[0010] The electromagnetic drive mechanism can switch the connection states of the first inlet and the second inlet with the first outlet and the second outlet, respectively, to change the pressure distribution in the first chamber and the second chamber, thereby forming a pressure difference on both sides of the piston and driving the piston to move against the reset force of the reset mechanism, and driving the slider to move in the switching chamber to change the flow path.

[0011] Furthermore, the valve body includes two parallel valve body pipes, and the drive chamber and the switching chamber are respectively located within the two valve body pipes;

[0012] The piston includes two sub-pistons located in the two valve body pipes respectively. The first outlet and the second outlet of the pilot valve assembly simultaneously deliver pressure to the drive chambers in the two valve body pipes through a diversion pipe to drive the two sub-pistons to move synchronously.

[0013] Furthermore, the first inlet of the pilot valve assembly is connected to the high-pressure exhaust end of the air conditioning system, and the second inlet is connected to the low-pressure intake end of the air conditioning system.

[0014] The pilot valve assembly uses the pressure difference between the high-pressure exhaust end and the low-pressure intake end as a driving source.

[0015] Furthermore, the pilot valve assembly is connected to the drive chambers in the two valve body pipes via multiple capillary tubes and a gas distribution valve. The capillary tubes are used to divert the gas pressure from the pilot valve assembly to the two valve body pipes.

[0016] Furthermore, the reset mechanism includes a helical spring disposed in the drive cavity, one end of the helical spring abutting against the inner wall of the valve body, and the other end abutting against the piston;

[0017] When the electromagnetic drive mechanism is not driven, the piston remains in a preset initial position under the action of the helical spring.

[0018] Furthermore, the slider is provided with a through hole penetrating the slider body;

[0019] The slider is configured to control the amount of fluid leakage during the switching process within a preset range by setting the shape or diameter of the through hole.

[0020] Furthermore, the piston and the connecting rod are rigidly connected by threaded fasteners;

[0021] The surface of the slider is made of Teflon material or coated with Teflon coating, and is sealed with lubricating oil.

[0022] Furthermore, the valve body has a cross-shaped structure, and the valve body is a component fixed by welding or an integrally formed structure, with sealing end caps at both ends of the valve body.

[0023] Furthermore, the pilot valve assembly is used to operate in response to a control signal;

[0024] When a signal is received indicating that the air conditioning system has entered defrost mode and the four-way valve in the air conditioning system has reversed, the pilot valve assembly remains in its current state and does not move, so that the slider remains in its original flow path position.

[0025] Upon receiving a shutdown command from the air conditioning system, the pilot valve assembly is de-energized after a preset delay, so that the pressure difference between the high-pressure and low-pressure ends of the air conditioning system is balanced before the piston is reset by the reset mechanism.

[0026] The present invention also proposes an air conditioning system, including a compressor, a four-way valve, a heat exchanger, a controller, and the above-mentioned active flow path switching valve;

[0027] The controller is used to control the operation of the four-way valve and the active flow path switching valve;

[0028] When the air conditioning system enters defrosting mode, the controller controls the four-way valve to switch direction and simultaneously controls the active flow path switching valve to maintain the original flow path position, so as to keep the refrigerant and the heat exchange medium in the heat exchanger in a co-current heat exchange state.

[0029] The present invention also proposes a control method for the above-mentioned air conditioning system, comprising: when a defrosting command is received, controlling the four-way valve to switch to the defrosting cycle; during the switching of the four-way valve and during the defrosting process, controlling the pilot valve assembly of the active flow path switching valve to remain in a non-operating state, thereby using the pilot valve assembly to lock the flow path state of the active flow path switching valve so that it does not switch with changes in system pressure.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] This invention utilizes a main valve assembly and a pilot valve assembly. The pilot valve assembly's active electromagnetic drive alters the pressure distribution within the main valve assembly's drive chamber, thereby driving a piston to move a slider and switch flow paths. This invention leverages the inherent high and low pressure difference within the air conditioning system as the driving force, eliminating the need for a high-power drive motor on the main valve, thus reducing cost and energy consumption. Furthermore, the use of an independently controllable pilot valve for active control decouples the flow path switching action from the pressure state of the system's main circuit. Even under conditions that cause system pressure reversals, such as defrosting, the main valve flow path can be locked by controlling the pilot valve's state. This avoids the malfunctions of traditional self-operated valves due to pressure fluctuations, enabling complex control strategies such as maintaining flow during defrosting to reduce pressure and improve defrosting efficiency, thereby enhancing the overall energy efficiency and operational reliability of the air conditioning system. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram illustrating the principle of an active flow path switching valve connected to an air conditioning system, as provided in an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the main structure of the active flow path switching valve provided in an embodiment of the present invention.

[0035] Figure 3 This is a schematic diagram of the main cross-sectional structure of the active flow path switching valve provided in an embodiment of the present invention.

[0036] Figure 4 This is a three-dimensional structural diagram of the active flow path switching valve provided in an embodiment of the present invention.

[0037] Figure 5 This is a cross-sectional structural diagram of the pilot valve assembly in the active flow path switching valve provided in an embodiment of the present invention.

[0038] Figure 6 This is a cross-sectional structural diagram of the main valve assembly in the active flow path switching valve provided in an embodiment of the present invention.

[0039] Figure 7 This is a three-dimensional exploded view of the active flow path switching valve provided in an embodiment of the present invention.

[0040] Among them, 1 is the compressor, 2 is the high-pressure switch, 3 is the four-way valve, 4 is the finned heat exchanger, 5 is the motor, 6 is the distributor, 7 is the filter, 8 is the electronic expansion valve, 9 is the active flow path switching valve, 10 is the gas-liquid separator, and 11 is the shell-and-tube heat exchanger.

[0041] 201 is the pilot valve bracket, 202 is the pilot valve solenoid core, 203 is the pilot valve body, 204 is the pilot valve body cover, 205 is the pilot valve core, 206 is the switching valve body, 207 is the cross valve body piping plate, 208 is the lower part of the cross valve body piping plate, 209 is the cross valve body valve plate, 210 is the piston, 211 is the slider, 212 is the end cap, 213 is the connecting rod, 214 is the copper screw, 215 is the low-pressure capillary tube, 216 is the low-pressure interface, 217 is the short L-shaped capillary tube, 218 is the long L-shaped capillary tube, 219 is the high-pressure interface, 220 is the high-pressure capillary tube, 221 is the pilot valve return spring, 222 is the spring, and 223 is the three-way valve. Detailed Implementation

[0042] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0043] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0044] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0045] Currently, air conditioning systems that rely on the flow path's own pressure for passive switching suffer from limitations in control and low defrosting efficiency. Taking a shell-and-tube heat exchanger as an example, its heat exchange efficiency is greatly affected by whether it flows in the same direction or in the opposite direction; typically, the heat exchange efficiency of counter-current flow can be about 15% higher than that of co-current flow.

[0046] This invention introduces an independent active control mechanism, enabling the valve body to maintain flow path stability even when system operating conditions change drastically, such as pressure reversal caused by defrosting, thereby improving the overall energy efficiency and reliability of the system.

[0047] Example 1

[0048] like Figures 2 to 7As shown, this embodiment provides an active flow path switching valve, which mainly consists of two parts: a main valve assembly and a pilot valve assembly.

[0049] The main valve assembly is the actuator that realizes the physical switching of the flow path. In order to adapt to the common requirement of simultaneous switching of gas and liquid pipes in air conditioning systems, the main valve assembly adopts a structure with two valve bodies in parallel.

[0050] Specifically, the core valve body of the main valve assembly mainly consists of a switching valve body 206, a cross valve body piping plate 207, a lower part of the cross valve body piping plate 208, a cross valve body valve plate 209, and an end cap 212.

[0051] The switching valve body 206, the cross valve body piping plate 207, and the lower part 208 of the cross valve body piping plate are welded together to form an integrated valve body, which forms the driving chamber and the switching chamber. Sealed end caps 212 are provided at both ends of the valve body. The end caps 212 are finally welded to the valve body body for sealing, thus ensuring the airtightness of the driving chamber under high-pressure conditions.

[0052] The valve body adopts a cross-shaped structure and is fixed by welding or integral molding, which greatly improves the overall structural strength and pressure resistance of the valve body and reduces potential leakage points. The design of sealing end caps at both ends not only facilitates the processing and assembly of the valve body, but also ensures good sealing of the drive chamber, preventing the drive pressure from leaking out, thereby ensuring stable output of drive force.

[0053] A movable linear motion mechanism is provided inside the main valve assembly. This linear motion mechanism mainly includes a piston 210, a slider 211, a connecting rod 213, and connecting fasteners.

[0054] Piston 210 is disposed in the drive chamber and divides the drive chamber into a first chamber and a second chamber. Due to the adoption of a dual valve body structure, piston 210 actually includes two sub-pistons located in two parallel pipes respectively.

[0055] The slider 211 is movably disposed in the switching chamber and slides against the surface of the cross valve body valve plate 209 to change the connection state of the flow path.

[0056] Link 213 connects piston 210 and slider 211, so that the movement of piston 210 can directly drive slider 211 to move.

[0057] To ensure reliable connection and prevent loosening during long-term reciprocating motion, piston 210 and connecting rod 213 are rigidly connected using threaded fasteners such as copper screws 214. Meanwhile, the lower end of slider 211 is assembled using a limiting structure to ensure accurate movement within the switching chamber.

[0058] By setting two parallel valve body pipes and corresponding sub-pistons, the flow capacity of the flow path switching valve can be significantly increased to meet the needs of high-flow-rate conditions. At the same time, the pressure of the pilot valve assembly is simultaneously delivered to the two drive chambers through the diversion pipeline, realizing the synchronous drive and movement of the two sub-pistons. This not only ensures the consistency and stability of dual flow path switching, but also effectively utilizes the space structure and improves the overall working efficiency of the valve.

[0059] To address the potential air leakage issue that may occur during the switching process of slider 211, this embodiment incorporates a special design for slider 211.

[0060] Specifically, the slider 211 has a through hole penetrating its body, and the through hole has a preset shape or diameter. During design and manufacturing, by accurately calculating and experimentally verifying, a specific through hole size and shape can be selected, which can control the fluid leakage of the slider 211 during the switching process within a preset range.

[0061] This invention features through-holes of a specific shape or diameter on the slider, allowing for precise control of fluid leakage during switching. This design, on the one hand, utilizes minute leakage to balance the pressure on both sides of the slider, preventing jamming or difficulty in movement due to excessive pressure differential; on the other hand, it controls leakage within a preset range, ensuring the valve's sealing performance while reducing wear through fluid lubrication and extending component lifespan.

[0062] In addition, the high and low pressure power chambers of the slider are sealed by gaskets, and the surface of the slider 211 and other sealing parts are made of Teflon material or coated with Teflon coating, and are sealed with lubricating oil and refrigerant. This not only reduces the coefficient of friction and extends the service life of the components, but also further improves the sealing performance.

[0063] A reset mechanism is also provided in the drive cavity. In this embodiment, a spring 222 is used as the reset mechanism. The spring 222 is an independent component, with one end abutting against the inner wall of the valve body, such as at the end cap 212, and the other end abutting against the piston 210.

[0064] The function of spring 222 is to apply a reset force to piston 210, defining the default safe position of the valve when power is off or there is no drive signal, such as the position corresponding to cooling mode. This mechanical reset design ensures that the valve has fail-safe characteristics.

[0065] In this invention, the reset mechanism employs a helical spring design, giving the valve an automatic reset function in the event of power failure or non-drive status. When the electromagnetic drive mechanism is not activated, the piston can reliably remain in the preset initial position under the action of the spring force, which serves as a fault protection function, ensuring that the flow path can automatically return to a safe or default connected state in the event of system malfunction or shutdown.

[0066] Unlike traditional self-operated valves that directly draw pressure from the flow channel, this embodiment introduces a pilot valve assembly as the core of active control. The pilot valve assembly is connected to the main valve assembly via a pilot valve bracket 201. The pilot valve assembly mainly includes a pilot valve body 203, a pilot valve body cover 204, a pilot valve core 205, a pilot valve solenoid core 202, and a pilot valve return spring 221.

[0067] The pilot valve body 203 and the pilot valve body cover 204 are integrally formed by welding. The pilot valve assembly has an electromagnetic drive mechanism, such as an electromagnetic coil, which can generate magnetic force in response to an electrical signal. The pilot valve solenoid core 202 can overcome the resistance of the pilot valve return spring 221 under the action of the electromagnetic coil and drive the pilot valve core 205 to move.

[0068] The pilot valve assembly has a first inlet and a second inlet, which are designed as a high-pressure interface 219 and a low-pressure interface 216, respectively. The high-pressure interface 219 is configured to connect to the high-pressure exhaust end of the air conditioning system, and the low-pressure interface 216 is configured to connect to the low-pressure intake end of the air conditioning system. This means that the pilot valve assembly utilizes the most stable high-low pressure difference in the air conditioning system as its driving source, rather than relying on the pressure fluctuations that may occur within the valve's own flow path.

[0069] This design cleverly utilizes the pressure difference between the high-pressure exhaust end and the low-pressure intake end of the air conditioning system as the driving source. This design eliminates the need for an additional power source for the main valve's operation; the pilot valve consumes very little electrical energy to control the large system pressure difference and drive the main valve. This significantly reduces valve energy consumption, simplifies the system structure, and improves the system's energy efficiency.

[0070] The pilot valve assembly also has a first outlet and a second outlet, which are respectively connected to the first and second chambers of the main valve assembly's drive chamber. To achieve synchronous drive of the two valve bodies, this embodiment employs a flow-dividing design. The pilot valve assembly is connected to the main valve assembly via a high-pressure capillary tube 220, a low-pressure capillary tube 215, and a gas-dividing three-way valve 223. High and low pressure gases are evenly diverted to the drive chambers within the two parallel valve body pipes via the gas-dividing three-way valve 223 and related short L-shaped capillary tubes 217 and long L-shaped capillary tubes 218. The two sets of gas supply lines are arranged symmetrically, and since the driving medium is pure gas, such as from the exhaust pipe and intake pipe, the capillary tube length has minimal impact on pressure transmission, ensuring the synchronicity of the dual valve responses.

[0071] This invention, by incorporating multiple capillary tubes and a gas distribution valve between the pilot valve assembly and the drive chamber, effectively diverts and throttles the high-pressure gas entering the drive chamber. The capillary tubes help balance the intake pressure within the two valve body pipes, preventing pressure surges from impacting internal components and ensuring a uniform and stable distribution of gas pressure to the two pipes, thereby further guaranteeing the synchronicity and smoothness of the dual-piston movement.

[0072] The pilot valve assembly works as follows: Under the drive of the electromagnetic drive mechanism, the pilot valve core 205 moves, switching the connection status of the first inlet (high pressure) and the second inlet (low pressure) with the first outlet and the second outlet, respectively.

[0073] For example, in the unenergized state, the first outlet is connected to low pressure and the second outlet is connected to high pressure; after energization, the state is reversed. This switching directly changes the pressure distribution in the first and second chambers within the main valve drive chamber, thereby creating a large pressure difference on both sides of the piston 210. This pressure difference drives the piston 210 to move against the reset force of the spring 222, which in turn drives the slider 211 to change the flow path.

[0074] The pilot valve assembly is used to respond to control signals and perform actions.

[0075] When a signal is received indicating that the air conditioning system has entered defrost mode and the four-way valve in the air conditioning system has reversed, the pilot valve assembly remains in its current state and does not move, so that the slider remains in its original flow path position.

[0076] Upon receiving a shutdown command from the air conditioning system, the pilot valve assembly is de-energized after a preset delay to allow the pressure difference between the high-pressure and low-pressure sides of the air conditioning system to balance before the piston is reset via the reset mechanism.

[0077] This control logic enables the pilot valve assembly to have intelligent response capabilities, especially under special operating conditions where the air conditioning system enters defrost mode and the four-way valve switches, maintaining its current state without action. This benefit solves the problem of erroneous switching of traditional valves due to pressure fluctuations caused by the system's four-way valve switching, forcing the slider to maintain its original flow path position, ensuring the continuity of system operation logic and the stability of the defrosting process. By delaying power-off after receiving a shutdown command, the system allows for reset only after the pressure difference between the high-pressure and low-pressure sides has balanced. This design avoids the mechanical impact and noise caused by the piston violently rebounding under large pressure differences, effectively protecting internal valve components from impact damage and significantly extending the valve's service life.

[0078] Based on the above configuration, this invention achieves active flow path switching control by employing a pilot valve assembly in conjunction with a main valve assembly. The pilot valve assembly controls the pressure distribution within the first and second chambers, thereby creating a pressure difference on both sides of the piston to drive the piston and slider movement. This design allows the valve switching action to no longer solely rely on the fluid's flow direction or passive pressure, but can be actively controlled by an electromagnetic drive mechanism. This improves the response speed and reliability of flow path switching, while the pressure difference drive effectively overcomes the resistance of the reset mechanism, ensuring smooth and powerful switching.

[0079] Example 2

[0080] like Figure 1 As shown, this embodiment provides an air conditioning system including the aforementioned active flow path switching valve. The air conditioning system includes a compressor 1, a high-pressure switch 2, a four-way valve 3, a finned heat exchanger 4, a motor 5, a distributor 6, a filter 7, an electronic expansion valve 8, a gas-liquid separator 10, a shell-and-tube heat exchanger 11, and a controller. The aforementioned active flow path switching valve 9 is installed in the system's piping and is used to switch the refrigerant flow direction.

[0081] In this system, the high-pressure port 219 of the pilot valve assembly is connected to the high-pressure pipeline near the discharge port of compressor 1, and the low-pressure port 216 is connected to the low-pressure pipeline near the suction port of compressor 1. This connection method ensures that the pilot valve can obtain a stable driving pressure differential as long as compressor 1 is running, regardless of whether the system is in cooling or heating mode. This is fundamentally different from the driving method in the prior art that relies on the heat exchanger side pressure.

[0082] Example 3

[0083] This embodiment elaborates on the control method of the above-mentioned air conditioning system, especially how to use an active flow path switching valve to achieve optimized control under all operating conditions.

[0084] In system standby mode, compressor 1 is not running, and the system's high and low pressures are balanced. At this time, the pressures of the low-pressure port 216 and the high-pressure port 219 are the same, the pilot valve assembly is de-energized, and the main valve assembly is held in its initial position by the action of spring 222, for example, chamber A is connected to the low-pressure end and chamber B is connected to the high-pressure end.

[0085] When the system starts in cooling mode, the controller's control flag X is 0, and the electromagnetic drive mechanism is not energized. The pilot valve assembly maintains its default state, allowing low pressure to flow on one side of the main valve drive chamber and high pressure to flow on the other side. For example, with the help of spring force, the slider 211 remains in the refrigeration flow path position. At this time, the refrigerant flow direction in the shell-and-tube heat exchanger 11 is counter-current to the water flow direction, resulting in optimal heat exchange efficiency.

[0086] When the system switches to heating mode, the four-way valve 3 reverses. The controller sends a signal to set flag X to 1, energizing the pilot valve assembly. The controller relay engages, the coil is energized, and the pilot valve core 205, under the action of the pilot valve solenoid core 202, overcomes the resistance of the pilot valve return spring 221, reversing the high and low pressures leading to the main valve drive chamber. Driven by the reverse pressure difference, the piston 210 overcomes the resistance of the spring 222, driving the slider 211 to switch the flow path. Through this switching, although the flow direction of the main circuit changes, the refrigerant flow through the shell-and-tube heat exchanger 11 is still adjusted to flow counter-currently to the water circuit, thus achieving efficient heat exchange even in heating mode. At the same time, this flow control keeps the refrigerant flowing from top to bottom, thereby improving the oil return performance on the heat exchanger side.

[0087] The core advantage of this embodiment lies in the control of the defrost mode. In traditional systems, entering defrost mode means that the four-way valve 3 must switch back, for example, switching back to the refrigeration cycle, which causes the system piping pressure to reverse. If it is a passive self-operated valve, it will be forced to switch due to the pressure reversal, resulting in a change in refrigerant flow direction. This may not only cause "backflow" defrosting inefficiency but also cause pressure fluctuations and noise. In this embodiment, when the controller determines that the system needs to enter defrost mode, while controlling the four-way valve 3 to switch, it controls the active flow path switching valve 9 to remain stationary through specific logic. Specifically, although the four-way valve 3 is activated, the controller controls the pilot valve assembly to maintain its current state, that is, the flag bit X remains at 1, or the solenoid state is locked according to specific logic, and no action is taken.

[0088] Because the pilot valve assembly not only provides driving force but also acts as a "pressure lock," it locks the pressure state of the main valve drive chamber, preventing it from changing with the main system pressure caused by the four-way valve 3. Therefore, the slider 211 remains in its original flow path position. At this time, although the system is in a refrigeration cycle for defrosting, the refrigerant and water sides are in a co-current flow state for the shell-and-tube heat exchanger 11. In this co-current flow state, the average heat exchange temperature difference decreases, reducing the amount of heat exchanged. This lowers the pressure of the circulating refrigerant, avoiding the high-pressure anomalies that often occur during defrosting. Simultaneously, due to the reduced heat dissipation, the exhaust temperature increases, utilizing higher-temperature gas for defrosting significantly enhances the defrosting effect and shortens the defrosting time. This control strategy cleverly utilizes the decoupling characteristics of the active valve, solving the long-standing pain point of difficult defrosting in water-fluorinated heat exchange systems.

[0089] In addition, this system also features a delayed reset protection function. Upon receiving a shutdown command, the controller does not immediately cut off the power to the active flow path switching valve 9, but instead delays it for a preset time, such as 3 minutes. This delay allows the pressure difference between the high-pressure and low-pressure ends of the system to gradually equalize. Once the pressure difference is balanced, the pilot valve is de-energized, and the main valve resets under the action of spring 222. This avoids the water hammer effect and mechanical impact noise caused by sudden reset under high pressure differential, extending the service life of the equipment.

[0090] To more clearly illustrate the control logic of the air conditioning system in this invention, particularly how the controller coordinates the actions of the four-way valve 3 and the active flow path switching valve 9, this embodiment provides the following specific control strategy. The controller can internally set a flag bit (denoted as X) for controlling the active flow path switching valve 9:

[0091] Cooling Mode Control (Default State): When the system is powered on and running in cooling mode, the controller sets the flag to X=0. At this time, the controller does not send an electrical signal to the pilot valve assembly of the active flow path switching valve 9 (the coil is de-energized). The pilot valve body maintains its initial state under the action of the return spring, ensuring the pressure distribution within the main valve drive chamber remains at the default level. The slider 211 remains in the cooling flow path position under the action of the spring 222. At this time, the refrigerant exchanges heat counter-currently with the water in the shell-and-tube heat exchanger 11, ensuring efficient cooling.

[0092] Heating Mode Control: When the system switches to heating mode, the controller controls the four-way valve 3 to switch directions and simultaneously sets the flag to X=1. The controller closes the relay, supplying power to the pilot valve assembly coil of the active flow path switching valve 9. The pilot valve actuates, reversing the pressure in the high and low pressure capillaries, changing the pressure distribution in chambers A and B of the main valve drive chamber. Under the action of the pressure difference, piston 210 moves against the resistance of spring 222, driving slider 211 to switch the flow path. This operation ensures that even in the heating cycle, the refrigerant flow direction in the shell-and-tube heat exchanger 11 remains countercurrent to the water side, and maintains the refrigerant inlet at the top and outlet at the bottom, optimizing oil return performance.

[0093] Defrosting mode control (special operating conditions): When the controller detects that the defrosting conditions are met, such as severe frost on the outdoor unit and issues a defrosting command, the system enters defrosting mode.

[0094] The controller controls the reversing of the four-way valve 3 to use the high-temperature refrigerant to melt the frost on the outdoor heat exchanger.

[0095] At this time, the controller does not reset the flag bit X to 0, but forces the flag bit X to be 1, that is, keeps the pilot valve assembly energized.

[0096] Although the system main circuit pressure reverses due to the four-way valve reversal, the pressure state within the drive chamber is locked due to the active control of the pilot valve, and the slider 211 remains stationary in its original heating flow path position. At this time, for the shell-and-tube heat exchanger 11, the refrigerant flow direction becomes co-current relative to the water path. In co-current flow, the average heat exchange temperature difference decreases, and the heat exchange capacity decreases, which leads to a proper reduction in the pressure of the circulating refrigerant in the system, avoiding the system high-pressure anomalies that often occur during defrosting. At the same time, due to the reduced heat dissipation on the water side, the exhaust temperature can rise rapidly, allowing the higher-temperature gas to enter the outdoor heat exchanger, significantly enhancing the defrosting effect and shortening the defrosting time.

[0097] Upon receiving a shutdown command, compressor 1 stops operating. The controller executes a delay logic, maintaining the X flag of the active flow path switching valve 9 unchanged; that is, if it is energized, it remains energized for a preset time, such as 3 minutes. After the pressure at the high-pressure and low-pressure ends of the system gradually balances, the controller disconnects the power to the active flow path switching valve 9. This allows piston 210 to return to its original position smoothly under low pressure differential conditions, avoiding mechanical shock noise and valve body damage caused by sudden power failure and reset under high pressure differential conditions.

[0098] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An active flow path switching valve, characterized in that, include: A main valve assembly, the main valve assembly including a valve body having a drive chamber and a switching chamber, a piston dividing the drive chamber into a first chamber and a second chamber, a slider movably disposed in the switching chamber, a connecting rod connecting the piston and the slider, and a reset mechanism for applying a reset force to the piston; A pilot valve assembly having an electromagnetic drive mechanism, a first inlet, a second inlet, a first outlet, and a second outlet, wherein the first outlet is connected to a first chamber, and the second outlet is connected to a second chamber; The electromagnetic drive mechanism can switch the connection states of the first inlet and the second inlet with the first outlet and the second outlet, respectively, to change the pressure distribution in the first chamber and the second chamber, thereby forming a pressure difference on both sides of the piston and driving the piston to move against the reset force of the reset mechanism, and driving the slider to move in the switching chamber to change the flow path.

2. The active flow path switching valve according to claim 1, characterized in that, The valve body includes two parallel valve body pipes, and the drive chamber and the switching chamber are respectively located in the two valve body pipes; The piston includes two sub-pistons located in the two valve body pipes respectively. The first outlet and the second outlet of the pilot valve assembly simultaneously deliver pressure to the drive chambers in the two valve body pipes through a diversion pipe to drive the two sub-pistons to move synchronously.

3. The active flow path switching valve according to claim 1, characterized in that, The first inlet of the pilot valve assembly is connected to the high-pressure exhaust end of the air conditioning system, and the second inlet is connected to the low-pressure intake end of the air conditioning system. The pilot valve assembly uses the pressure difference between the high-pressure exhaust end and the low-pressure intake end as a driving source.

4. The active flow path switching valve according to claim 2, characterized in that, The pilot valve assembly is connected to the drive chambers in the two valve body pipes via multiple capillary tubes and a gas distribution valve. The capillary tubes are used to divert the gas pressure from the pilot valve assembly to the two valve body pipes.

5. The active flow path switching valve according to claim 1, characterized in that, The reset mechanism includes a helical spring disposed in the drive cavity, one end of the helical spring abutting against the inner wall of the valve body, and the other end abutting against the piston; When the electromagnetic drive mechanism is not driven, the piston remains in a preset initial position under the action of the helical spring.

6. The active flow path switching valve according to claim 1, characterized in that, The slider has a through hole that penetrates the slider body; The slider is configured to control the amount of fluid leakage during the switching process within a preset range by setting the shape or diameter of the through hole.

7. The active flow path switching valve according to claim 1, characterized in that, The piston and the connecting rod are rigidly connected by threaded fasteners; The surface of the slider is made of Teflon material or coated with Teflon coating, and is sealed with lubricating oil.

8. The active flow path switching valve according to claim 1, characterized in that, The valve body has a cross-shaped structure and is either a component fixed by welding or an integrally formed structure. Both ends of the valve body are provided with sealing end caps.

9. The active flow path switching valve according to claim 1, characterized in that, The pilot valve assembly is used to operate in response to control signals; When a signal is received indicating that the air conditioning system has entered defrost mode and the four-way valve in the air conditioning system has reversed, the pilot valve assembly remains in its current state and does not move, so that the slider remains in its original flow path position. Upon receiving a shutdown command from the air conditioning system, the pilot valve assembly is de-energized after a preset delay, so that the pressure difference between the high-pressure and low-pressure ends of the air conditioning system is balanced before the piston is reset by the reset mechanism.

10. An air conditioning system, characterized in that, Includes a compressor, a four-way valve, a heat exchanger, a controller, and an active flow path switching valve as described in any one of claims 1-9; The controller is used to control the operation of the four-way valve and the active flow path switching valve; When the air conditioning system enters defrosting mode, the controller controls the four-way valve to switch direction and simultaneously controls the active flow path switching valve to maintain the original flow path position, so as to keep the refrigerant and the heat exchange medium in the heat exchanger in a co-current heat exchange state.

11. A control method for an air conditioning system as described in claim 10, characterized in that, include: When a defrosting command is received, the four-way valve is controlled to switch to the defrosting cycle; During the switching of the four-way valve and the defrosting process, the pilot valve assembly of the active flow path switching valve remains inactive, thereby using the pilot valve assembly to lock the flow path state of the active flow path switching valve so that it does not switch with changes in system pressure.

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