A pneumatic element closed-loop air supply solenoid valve

Abstract

This application discloses a closed-loop air supply solenoid valve for pneumatic components, belonging to the field of pneumatic solenoid valves. It includes a pneumatic actuator, a solenoid valve body, and an air path reversing assembly. The pneumatic actuator includes a rod-type A chamber and a rodless B chamber with a spring. The air path reversing assembly has a reversing C chamber and an inner guide D chamber located inside the reversing C chamber. The reversing C chamber is connected to the solenoid valve's output port and the drive B chamber, respectively. The spring A chamber is connected to the inner guide D chamber. When the solenoid valve is energized, the inner guide D chamber is closed, and clean compressed medium is delivered to the drive B chamber through the main reversing C chamber. When the solenoid valve is de-energized, the inner guide D chamber is unclosed, and the clean compressed medium inside the drive B chamber flows through the main reversing C chamber and the inner guide D chamber to the spring A chamber. This internal closed-loop air supply circulation structure, during reset, relies on the clean compressed medium in the rodless B chamber to fill the rod-type A chamber to compensate for the volume difference, extending the service life of the actuator and reducing maintenance and replacement costs.

Description

Technical Field

[0001] This application belongs to the field of pneumatic solenoid valves, and particularly relates to a closed-loop air supply solenoid valve for pneumatic components. Background Technology

[0002] In the field of industrial automation control, the combined control scheme of a single-acting spring-return pneumatic actuator and a solenoid valve is widely used. The conventional assembly method involves directly integrating the solenoid valve onto the outside of the pneumatic actuator, with the solenoid valve's working air port connected to the actuator's air inlet chamber. When the solenoid valve is energized, compressed air enters the actuator, driving the piston to overcome the spring force and complete the opening / closing action. When the solenoid valve is de-energized, the valve circuit switches to the exhaust state, and the spring inside the actuator releases its force, pushing the piston back to its original position. This achieves automatic switching between the two operating states of the valve. However, this traditional control combination has a drawback when operating in harsh industrial environments with dust, acid and alkali corrosion, and high humidity for extended periods: when the solenoid valve is de-energized and the spring drives the actuator to return to its original position, the internal volume of the actuator's spring chamber increases, creating negative pressure. External ambient air is then drawn back into the spring chamber through the solenoid valve's exhaust port. In chemical, metallurgical, and mining environments, the ambient air contains a mixture of various pollutants, including solid dust, acidic / alkaline corrosive vapors, condensed water vapor, and salt spray. This contaminated air continuously remains within the spring's sealed cavity, causing long-term erosion of the internal components of the actuator. Therefore, existing technologies require further improvement and enhancement. Summary of the Invention

[0003] This invention provides a closed-loop air supply solenoid valve for pneumatic components, which solves the problem of negative pressure generated in the spring chamber when the pneumatic actuator is de-energized and reset, drawing in outside air containing pollutants through the solenoid valve's exhaust port, causing long-term corrosion of internal components and short service life under harsh working conditions, or at least provides a beneficial alternative.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A closed-loop air supply solenoid valve for pneumatic components includes a pneumatic actuator, a solenoid valve body, and an air circuit reversing assembly. The pneumatic actuator includes a rod-loaded chamber A and a rodless chamber B, both equipped with springs. The air circuit reversing assembly is provided with a reversing C chamber and an inner guide D chamber located inside the reversing C chamber. The reversing C chamber is connected to the output air port of the solenoid valve and the drive B chamber, respectively. The spring A chamber is connected to the inner guide D chamber. When the solenoid valve is energized, the internal guide chamber D is in a closed isolation state, and the clean compressed medium is delivered to the drive chamber B through the main reversing chamber C, driving the pneumatic actuator to complete the stroke action; When the solenoid valve is de-energized, the inner guide chamber D is unsealed and connected to the reversing chamber C, driving the clean compressed medium inside chamber B through the main reversing chamber C and the inner guide chamber D to the spring chamber A.

[0005] In a preferred embodiment, the gas path reversing assembly includes a reversing housing with an inner liner inside. The cavity inside the inner liner forms the inner guide cavity D. One end of the inner liner is connected to the inner wall of the reversing housing, and the other end is equipped with an axially sliding sealing plug. When the solenoid valve is energized, the sealing plug moves toward the port of the inner liner and seals the port. When the solenoid valve is de-energized, the sealing plug slides in the opposite direction and disengages from the port, and the inner guide cavity D and the reversing cavity C become connected. In the preferred implementation, when the solenoid valve is energized, the compressed medium flowing into the reversing chamber C acts on the back side of the sealing plug, pushing the sealing plug to move towards the inner bushing port and sealing the port; when the solenoid valve is de-energized, the reversing chamber C connects to the solenoid valve exhaust channel to release pressure, and the compressed medium flowing back from the rodless chamber B acts on the front side of the sealing plug, pushing the sealing plug away from the inner bushing port in the opposite direction.

[0006] In a preferred embodiment, the reversing housing has a first air port connected to the output port of the solenoid valve, and a second air port and a third air port respectively connected to the rod-type A chamber and the rodless B chamber; the inner liner has a fourth air port, which is in fluid communication with the second air port; the first air port is located in the chamber area on the back side of the sealing plug, and the third air port is located in the chamber area on the front side of the sealing plug.

[0007] In a preferred embodiment, the sealing plug is a bowl-shaped elastic conical structure, with the outer side of the bowl being the back side of the plug and the inner side being the front side of the plug. The inner liner is cylindrical, and the outer diameter of the inner liner is equal to the inner diameter of the bottom of the sealing plug bowl.

[0008] In the preferred implementation, after the compression medium acts on the back side of the plug to make the inner liner fit against the bottom of the sealing plug bowl, the edge of the large diameter end of the sealing plug bends towards the center to press the port of the inner liner and make the third air port and the first air port connected.

[0009] In a preferred embodiment, the axial dimension of the sealing plug is greater than the diameter of the first air port; the first air port is located near the inner wall of the reversing housing end; when the sealing plug slides to the back side and fits against the inner wall of the reversing housing, the sealing plug blocks the first air port, allowing the compressed medium to enter the inner guide D cavity and then enter the rod A cavity via the fourth air port and the second air port.

[0010] In the preferred implementation, the large end edge of the sealing plug is a sealing plane that adapts to the inner wall of the reversing housing. When the sealing plug slides to the back side and fits against the inner wall of the reversing housing end, the sealing plane fits tightly against the inner wall of the reversing housing and seals.

[0011] In a preferred embodiment, the wall of the reversing housing corresponding to the inner liner is provided with at least one pressure relief through hole.

[0012] In a preferred embodiment, the reversing housing and the solenoid valve body are integrated to form a single structure.

[0013] The above structure has the following beneficial effects: The pneumatic component closed-loop air supply solenoid valve of this application adopts an internal closed-loop air supply circulation structure. During reset, it relies on the clean compressed medium in the rodless B chamber to fill the rod-driven A chamber to compensate for the volume difference. External pollutants such as dust, acid and alkali vapors, salt spray, and water vapor cannot enter the chamber through the solenoid valve exhaust port, avoiding corrosion and rust of the spring, piston, and seals, greatly extending the service life of the actuator and reducing operation and maintenance replacement costs.

[0014] The pneumatic closed-loop air supply solenoid valve of this application provides a clean compressed medium that flows back into the rod-driven A chamber during the power-off phase to form an auxiliary air pressure. This auxiliary air pressure, together with the spring, pushes the piston back, sharing the spring's rebound load and allowing the auxiliary spring to fully extend and restore its original shape. This prevents the spring from experiencing weak rebound, deformation, or fatigue fracture due to long-term unilateral force.

[0015] The pneumatic closed-loop air supply solenoid valve of this application integrates the reversing housing and the solenoid valve body into one piece, eliminating the need for external pipelines and adapters, reducing air and dirt leakage gaps, and exhibiting excellent vibration and impact resistance. The overall structure is compact and easy to assemble, making it suitable for industrial sites with high dust, high corrosion, and strong vibration, such as chemical, mining, and metallurgical industries. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain this application and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The diagram illustrates a schematic embodiment of the closed-loop air supply solenoid valve of the pneumatic component of this application in the energized state. Figure 2 The diagram illustrates a schematic embodiment of the closed-loop air supply solenoid valve of the pneumatic components of this application under the condition of power failure. Figure 3 A schematic diagram illustrating one embodiment of the sealing plug of this application is shown. Label Explanation: 1. Pneumatic actuator; 10. Rod-driven A chamber; 11. Rodless B chamber; 2. Solenoid valve body; 20. Output port; 21. Input port; 22. Exhaust port; 3. Air circuit reversing assembly; 30. Reversing housing; 300. Reversing C chamber; 301. First port; 302. Second port; 303. Third port; 304. Exhaust through hole; 31. Inner bushing; 310. Flow guide D chamber; 311. Fourth port; 32. Sealing plug; 320. Back side of plug; 321. Front side of plug; 322. Sealing plane. Detailed Implementation

[0017] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit and scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0018] The present invention will now be described with reference to the accompanying drawings.

[0019] The specific solution adopted is as follows: like Figure 1-3 As shown, the present invention provides a closed-loop air supply solenoid valve for pneumatic components, comprising a pneumatic actuator 1, a solenoid valve body 2, and an air circuit reversing assembly 3; The pneumatic actuator 1 includes a rod-loaded A chamber 10 and a rodless B chamber 11 with springs. The air circuit reversing assembly 3 is provided with a reversing C chamber 300 and an inner guide D chamber 310 located inside the reversing C chamber 300. The reversing C chamber 300 is connected to the solenoid valve output port 20 and the drive B chamber, respectively. The spring A chamber is connected to the inner guide D chamber 310. When the solenoid valve is energized, the inner guide chamber D 310 is in a closed isolation state, and the clean compressed medium is delivered to the drive chamber B through the main reversing chamber C 300, driving the pneumatic actuator 1 to complete the stroke action. When the solenoid valve is de-energized, the inner guide chamber D 310 is unsealed and connected to the reversing chamber C 300, driving the clean compressed medium inside chamber B through the main reversing chamber C 300 and the inner guide chamber D 310 to the spring chamber A.

[0020] Solenoid valve energized operation process After the solenoid valve is energized, the clean compressed medium is sent into the reversing chamber C through the solenoid valve's output port 20. The internal switching structure of the air circuit reversing assembly 3 is activated, isolating and sealing the inner guide chamber D. At this time, the clean compressed medium only flows along the reversing chamber C and is delivered to the rodless chamber B 11. The pressure in the rodless chamber B 11 increases, pushing the piston of the pneumatic actuator 1 to compress the return spring in the rod chamber A. The piston completes its outward working stroke, realizing the opening and closing control of the matching valve. During this process, the volume of the rod chamber A contracts, and the original medium in the chamber can complete the internal depressurization along the corresponding channel of the inner guide chamber D 310. No external air enters the chamber throughout the entire process.

[0021] Solenoid valve de-energization operation process After the solenoid valve is de-energized, the output path of the solenoid valve switches to depressurize. The internal switching structure of the gas reversing assembly 3 releases the closure of the inner guide chamber D. The reversing chamber C 300 and the inner guide chamber D 310 are interconnected. The return spring inside the rod chamber A 10 releases its elastic force, pushing the piston back in the reverse stroke, compressing the clean compression medium inside the rodless chamber B. The clean compression medium stored in the rodless chamber B flows sequentially through the reversing chamber C 300 and the inner guide chamber D 310 in the conducting state, and finally fills the rod chamber A 10 to compensate for the increased internal volume of the rod chamber A 10 when the piston returns.

[0022] This application's solution achieves a closed-loop internal air supply circulation, relying on the clean compressed medium retained in the rodless B chamber to directly fill the rod-driven A chamber 10, preventing contaminants such as dust, acid and alkali mists, and water vapor from being drawn back into the actuator. Core components such as springs, pistons, and seals, which are in long-term contact with the clean medium, will not experience problems such as corrosion, jamming, or accelerated wear.

[0023] During the reset phase, the clean compressed medium flowing into the rod A chamber can form positive air pressure support, share the spring rebound load, and help the spring fully stretch and restore its initial shape. This avoids the spring from being subjected to long-term unilateral force, which can lead to weak rebound, deformation jamming, fatigue failure, and extend the service life of the spring.

[0024] The gas path is independently connected in two zones, and the switching logic between the two working conditions is clear. Through the dual-chamber partition design of the reversing C chamber 300 and the flow guiding D chamber 310, when energized, gas is supplied to the rodless B chamber to drive the piston to move. When de-energized, the two chambers are connected to realize the internal gas return. The gas path does not interfere with each other in the two working states, and the action switching is stable and reliable.

[0025] In a preferred embodiment of this application, the gas path reversing assembly 3 includes a reversing housing 30, inside which is provided an inner bushing 31. The cavity inside the inner bushing 31 forms an inner guide cavity D 310. One end of the inner bushing 31 is connected to the inner wall of the reversing housing, and the other end is equipped with an axially sliding sealing plug 32. When the solenoid valve is energized, the sealing plug 32 slides axially toward the port side of the inner bushing 31, and the sealing plug 32 fits and seals the port of the inner bushing 31, thus isolating and sealing the inner guide cavity D. At this time, the clean compressed medium output by the solenoid valve can only flow inside the reversing cavity C. The medium is transported to the rodless cavity B through the reversing cavity C. The pressure in the rodless cavity B increases, pushing the piston to compress the return spring inside the rod cavity A. The actuator completes its working stroke, and the matching valve realizes the opening and closing action. In this state, the inner guide cavity D and the reversing cavity C are isolated from each other, and the gas is supplied to the rodless cavity B in only one direction.

[0026] After the solenoid valve is de-energized, the sealing plug 32 slides in the opposite direction along the axial direction, disengaging from the port of the inner bushing 31, and the inner guide chamber D and the reversing chamber C become connected. The return spring releases its elastic force to drive the piston back, and the clean compressed medium stored in the rodless chamber B can flow sequentially through the reversing chamber C and the inner guide chamber D in the inner bushing 31, and finally fill the rod chamber A, compensating for the volume loss caused by the expansion of the rod chamber A 10 during the piston's return; the internal clean gas circulates, and no external ambient air enters the chamber throughout the entire process.

[0027] The axial sliding of the sealing plug 32 can be achieved in various ways, such as magnetic adsorption, magnetic repulsion, mechanical pushing, etc. In this embodiment, the pneumatic pressure differential drive method is preferred, which relies solely on the system's own compressed medium pressure to complete the plug displacement switching without the need for additional auxiliary drive components.

[0028] For details, see Figure 1 and Figure 2 When the solenoid valve is energized, the compressed medium enters the reversing chamber C and acts on the back side of the sealing plug 32. The medium pressure pushes the sealing plug 32 to move towards the port of the inner bushing 31 and seals the port, thus isolating the inner guide chamber D. Clean compressed medium is sent into the rodless chamber B only through the reversing chamber C, pushing the piston to compress the return spring, and the actuator completes its working stroke.

[0029] When the solenoid valve is de-energized, the reversing chamber C connects to the solenoid valve's exhaust passage to release pressure, and the pressure on the back side of the sealing plug 32 disappears. The compressed medium flowing back from the rodless chamber B acts on the front side of the sealing plug 32, pushing the plug away from the inner bushing 31 port, and the inner guide chamber D connects with the reversing chamber C. The return spring drives the piston to return, and the clean compressed medium from the rodless chamber B flows through the reversing chamber C and the inner guide chamber D to fill the rod-loaded chamber A, compensating for the volume difference caused by the expansion of the chamber.

[0030] The sealing plug 32 is moved by air pressure differential, eliminating the need for additional parts, simplifying the structure, reducing processing and assembly costs, and making it less prone to jamming and failure under harsh working conditions. The entire air circuit achieves internal closed-loop circulation. During reset, the spring cavity is filled with clean internal air source, preventing negative pressure from drawing in external polluted air and avoiding dust, corrosive moisture from eroding the piston, spring, and seals. The return gas enters the rod A cavity to form auxiliary air pressure, which works with the spring to complete the piston return stroke. The auxiliary spring fully restores its original deformation, alleviates spring fatigue, and ensures that the reset stroke is consistent and in place each time.

[0031] In this embodiment, the reversing housing 30 of the air circuit reversing assembly 3 has three independent air ports: a first air port 301 connected to the output port of the solenoid valve, a second air port 302 connected to the rod-equipped A chamber, and a third air port 303 connected to the rodless B chamber; an inner bushing 31 is fixed inside the reversing housing 30, and a fourth air port 311 is opened on the side wall of the inner bushing 31, which is in fluid communication with the second air port 302; in terms of spatial layout, the first air port 301 is arranged in the chamber area corresponding to the back side of the sealing plug 32, and the third air port 303 is arranged in the chamber area corresponding to the front side of the sealing plug 32.

[0032] A sealing plug 32 is installed inside the reversing housing 30. The sealing plug 32 is a bowl-shaped elastic cone structure. The outer side of the bowl forms the back side 320 of the plug, and the inner cavity of the bowl forms the front side 321 of the plug. The outer diameter of the inner bushing 31 is equal to the inner diameter of the bottom of the sealing plug 32. The axial dimension of the sealing plug 32 is larger than the width of the first air port 301. The first air port 301 is located near the inner wall of the end of the reversing housing 30.

[0033] When the solenoid valve is energized, the compressed medium flows from the output port 20 into the reversing C chamber 300. The compressed medium continuously acts on the back side of the sealing plug 32, pushing the sealing plug 32 to slide axially towards the inner bushing 31. The bottom of the sealing plug 32 precisely fits against the outer wall of the end of the inner bushing 31. Under the pressure of the medium, the edge of the large-diameter end of the sealing plug 32 elastically bends towards the center, tightly pressing the port of the inner bushing 31, forming a barrier seal for the inner guide D chamber. At this time, the third port 303 is directly connected to the chamber where the first port 301 is located, and the compressed medium can be transported to the rodless B chamber through the first port 301, the reversing C chamber, and the third port 303.

[0034] Furthermore, when the solenoid valve is de-energized, the sealing plug 32 moves axially towards the back side until it abuts against the inner wall of the reversing housing 30. The sealing plane 322 at the large end of the plug completely fits against the inner wall of the reversing housing 30, and the two are tightly pressed together to achieve a surface seal. Relying on the longer axial dimension of the sealing plug 32, the first air port 301 is completely covered and blocked, blocking the external exhaust passage of the first air port 301. The compressed medium in the cavity can only flow into the inner guide D cavity, and then through the fourth air port 311 and the second air port 302 into the rod-loaded A cavity. After the flat and fitted sealing plane 322 is in place, it can completely press against the housing wall, ensuring the sealing performance of the first air port 301 and preventing the medium from leaking out.

[0035] When the sealing plug 32 moves axially from the inner wall of the housing end to the inner bushing 31 side, the airflow blows the inclined surface of the bowl and generates a horizontal component of the thrust. The frictional resistance between the smooth sealing surface 322 and the inner wall of the reversing housing 30 is small. The medium continues to act on the back side 320 of the plug, pushing the bottom of the plug bowl to fit with the end of the inner bushing 31. The pressure forces the edge of the large diameter end of the plug to bend elastically towards the center, pressing the port of the inner bushing 31 to isolate the inner guide D cavity. At this time, the chambers where the first air port 301 and the third air port 303 are located are connected to each other.

[0036] See Figures 1-3 The reversing housing 30 and the inner liner 31 have at least one pressure relief hole in their corresponding wall.

[0037] After the solenoid valve is energized, the clean compressed medium is sent into the back chamber of the sealing plug 32 through the solenoid valve output port 20 and the first port 301. The medium pressure continuously acts on the back side 320 of the plug, pushing the sealing plug 32 to slide axially towards the port of the inner bushing 31. The bottom of the plug cup fits against the end of the inner bushing 31, and the back side air pressure squeezes the large diameter end of the plug to bend elastically towards the center, pressing the port of the inner bushing 31, and the inner guide D chamber is completely isolated. At this time, the reversing C chamber where the first port 301 and the third port 303 are located are interconnected. The high-pressure clean compressed medium is filled into the rodless B chamber through the pipeline connected by the third port 303, pushing the piston to compress the return spring inside the rod A chamber, and the actuator completes the extension working stroke. During piston compression, the volume of the rod-driven A chamber continuously decreases. Excess gas in the chamber flows into the inner guide D chamber of the inner bushing 31 through the second air port 302 and the fourth air port 311 connected by the pipeline, and is finally discharged outward through the pressure relief hole on the wall of the reversing housing 30. The excess medium in the spring chamber is released by the pressure relief hole throughout the process, and there is no backflow of external air.

[0038] The moment the solenoid valve loses power, the output channel of the solenoid valve switches to the exhaust and pressure relief state, the first air port 301 connects with the exhaust port to release pressure to the outside, and the pressure on the back side of the sealing plug 32 disappears quickly; the high-pressure clean medium remaining in the rodless B chamber acts on the front side of the sealing plug 32 through the third air port 303, pushing the plug to slide towards the inner wall of the end of the reversing housing 30.

[0039] After the sealing plug 32 moves to the end of the housing, the sealing plane 322 of the large end of the plug fits tightly against the inner wall of the reversing housing 30. It seals the first air port 301 by relying on the axial dimension larger than the diameter of the first air port 301, cuts off the exhaust channel of the solenoid valve, and the port of the inner bushing 31 is completely exposed. The inner guide D chamber and the reversing C chamber are interconnected. The return spring releases its elastic force to drive the piston to return and compress the rodless B chamber. The clean compression medium inside the rodless B chamber flows sequentially through the third air port 303, the reversing C chamber, the inner guide D chamber, the fourth air port 311, and the second air port 302, filling the expanded rod A chamber to compensate for the volume difference caused by the increase in the volume of the chamber. The negative pressure is eliminated by relying on the internal clean air source.

[0040] When the air pressure inside chamber A of the rod reaches the upper limit of the design rated pressure, the excess compressed medium that continues to flow in no longer remains in the spring chamber and is directly discharged through the pressure relief hole in the wall of the reversing housing 30. The entire airflow circulates in a closed loop only inside the valve body and the actuator, and no external impurities enter.

[0041] In a preferred embodiment of this application, the reversing housing 30 and the solenoid valve body 2 are integrated into a single structure. This integration of the reversing housing 30 and the solenoid valve body 2, along with the adapter joint, significantly reduces potential leak points in the pipeline, resulting in enhanced overall airtightness. This prevents dust and moisture from entering the internal air passage through gaps in the joints under harsh operating conditions. The overall structure is compact, occupying less installation space, facilitating placement in confined equipment workstations, and meeting the compact assembly requirements of automated equipment. After integration, the air passages are directly internally connected, resulting in a shorter airflow path, lower medium pressure loss, and faster application of the solenoid valve output pressure to the sealing plug 32. This leads to faster opening, closing, and reset response times for the actuator, and higher control sensitivity.

[0042] For any parts not mentioned in this invention, existing technologies can be used or referenced.

[0043] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A closed-loop air supply solenoid valve for pneumatic components, characterized in that, It includes a pneumatic actuator, a solenoid valve body, and an air circuit reversing assembly; The pneumatic actuator includes a rod-loaded chamber A and a rodless chamber B, both equipped with springs. The air circuit reversing assembly is provided with a reversing C chamber and an inner guide D chamber located inside the reversing C chamber. The reversing C chamber is connected to the output air port of the solenoid valve and the drive B chamber, respectively. The spring A chamber is connected to the inner guide D chamber. When the solenoid valve is energized, the internal guide chamber D is in a closed isolation state, and the clean compressed medium is delivered to the drive chamber B through the main reversing chamber C, driving the pneumatic actuator to complete the stroke action; When the solenoid valve is de-energized, the inner guide chamber D is unsealed and connected to the reversing chamber C, driving the clean compressed medium inside chamber B through the main reversing chamber C and the inner guide chamber D to the spring chamber A.

2. The closed-loop air supply solenoid valve for pneumatic components according to claim 1, characterized in that, The air circuit reversing assembly includes a reversing housing, an inner liner inside the reversing housing, and an inner cavity inside the inner liner forming the inner guide D cavity. One end of the inner liner is connected to the inner wall of the reversing housing, and the other end is equipped with an axially sliding sealing plug. When the solenoid valve is energized, the sealing plug moves towards the inner bushing port and seals the port; when the solenoid valve is de-energized, the sealing plug slides in the opposite direction and disengages from the port, and the inner guide chamber D and the reversing chamber C become connected.

3. The closed-loop air supply solenoid valve for pneumatic components according to claim 2, characterized in that, When the solenoid valve is energized, the compressed medium flowing into the reversing chamber C acts on the back side of the sealing plug, pushing the sealing plug towards the inner bushing port and sealing the port; when the solenoid valve is de-energized, the reversing chamber C connects to the solenoid valve exhaust channel to release pressure, and the compressed medium flowing back from the rodless chamber B acts on the front side of the sealing plug, pushing the sealing plug away from the inner bushing port in the opposite direction.

4. The closed-loop air supply solenoid valve for pneumatic components according to claim 3, characterized in that, The reversing housing has a first air port connected to the output port of the solenoid valve, and a second air port and a third air port respectively connected to the rod-type A chamber and the rodless B chamber; the inner liner has a fourth air port, which is in fluid communication with the second air port. The first air port is located in the chamber area on the back side of the sealing plug, and the third air port is located in the chamber area on the front side of the sealing plug.

5. The closed-loop air supply solenoid valve for pneumatic components according to claim 3, characterized in that, The sealing plug is a bowl-shaped elastic conical structure, with the outer side of the bowl being the back side of the plug and the inner side being the front side of the plug. The inner liner is cylindrical, and the outer diameter of the inner liner is equal to the inner diameter of the bottom of the sealing plug bowl.

6. The closed-loop air supply solenoid valve for pneumatic components according to claim 5, characterized in that, After the compressed medium acts on the back side of the plug to make the inner liner fit against the bottom of the sealing plug bowl, the edge of the large diameter end of the sealing plug bends towards the center to press the inner liner port and connect the third air port and the first air port.

7. The closed-loop air supply solenoid valve for pneumatic components according to claim 5, characterized in that, The axial dimension of the sealing plug is greater than the diameter of the first air port; the first air port is located near the inner wall of the reversing housing end; when the sealing plug slides to the back side and fits against the inner wall of the reversing housing, the sealing plug blocks the first air port, allowing the compressed medium to enter the inner guide D cavity and then enter the rod A cavity through the fourth air port and the second air port.

8. The closed-loop air supply solenoid valve for pneumatic components according to claim 6, characterized in that, The large end edge of the sealing plug is a sealing plane that fits the inner wall of the reversing housing. When the sealing plug slides to the back side and fits against the inner wall of the reversing housing end, the sealing plane fits tightly against the inner wall of the reversing housing and seals.

9. The closed-loop air supply solenoid valve for pneumatic components according to claim 2, characterized in that, The reversing housing and the inner liner have at least one pressure relief through hole in their corresponding wall sections.

10. The closed-loop air supply solenoid valve for pneumatic components according to claim 2, characterized in that, The reversing housing and the solenoid valve body are integrated to form a single structure.

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