Solenoid valve

Abstract

The electromagnetic valve comprises a shell, a static iron core is arranged in the shell, a push rod shaft penetrates through a shaft hole of the static iron core, the front end of the push rod shaft is connected with a piston, the rear end of the push rod shaft is connected with a movable iron core, a reset spring is arranged on the push rod shaft in a sleeving mode and located between the static iron core and the movable iron core, a framework and a coil are arranged on the outer side of the movable iron core, and a sleeve is arranged on the inner side of the framework; the front end and the rear end of the shell are connected with the valve seat and the connector respectively, the glyd ring is arranged between the piston and the static iron core, and the guide ring is arranged between the push rod shaft and the static iron core. The Glyd ring and the guide ring are combined, so that sliding sealing performance, low friction resistance and guidance quality are achieved; a special-shaped sealing gasket is arranged on the piston, and high sealing performance is achieved through the brand-new sealing gasket design.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic actuators, and in particular to a solenoid valve, which is mainly used in air suspension systems. Background Art

[0002] The air suspension system uses compressed air to replace traditional metal springs to transmit force and torque between the wheels and the frame, buffer the impact force transmitted to the frame or body by uneven roads, and attenuate the resulting vibration, thereby ensuring that the vehicle can travel smoothly. It can also automatically adjust the height of the vehicle according to different road conditions and the signal of the distance sensor to adapt to different driving conditions and road conditions.

[0003] The solenoid valve is a key component in the air suspension system. The opening and closing of the solenoid valve controls the stiffness of the air spring, thereby achieving the adjustment of the air suspension system. The existing solenoid valve structure has the following problems: (1) When the solenoid valve is actuated, the push rod shaft, the moving iron core and the piston all move axially. Since these components are clearance-fitted, it is easy for the push rod shaft and the stationary iron core, the moving iron core and the sleeve, and the piston and the stationary iron core to tilt and get stuck during the movement; (2) Inlet and outlet holes are provided on the valve seat. The inlet and outlet holes are closed and opened by the axial displacement of the piston. When closed, a reliable seal is required between the piston and the valve seat. At present, ordinary sealing gaskets are used for sealing. This sealing method is prone to leakage from the gap between the sealing gasket and the valve seat, and the sealing effect is not satisfactory. (3) The silencer pad that reduces the opening noise is mostly set at the tail of the armature (i.e. the moving iron core). The armature has a high heat generation temperature, so the silencer pad material has high temperature resistance requirements. The material cost is high and it is not easy to detect after it falls off; (4) The return spring in the existing solenoid valve uses an ordinary fixed pitch spring, which leads to a relatively long response time for the opening and closing of the solenoid valve; (5) When the piston moves axially in the piston cavity, the pressure inside the piston cavity is not easy to change because it is in a sealed state. A larger working pressure is required when opening and a larger electromagnetic force is required when closing. Which component structures on both sides cause the solenoid valve to have a large working pressure and a large electromagnetic force in the closed valve state?

[0004] Therefore, in view of the above problems, the present invention improves the structure of the existing solenoid valve and provides a solenoid valve structure that can solve the above problems. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in order to overcome the deficiencies in the prior art, the present invention provides a solenoid valve.

[0006] The technical solution to be adopted by the present invention to solve its technical problems is: an electromagnetic valve, including a shell, a static iron core is fixedly connected in the shell, a push rod shaft axially passes through the shaft hole of the static iron core and is slidably connected in its shaft hole, the front end of the push rod shaft is connected to the piston, and the rear end is connected to the moving iron core, a return spring is sleeved on the push rod shaft and is located between the static iron core and the moving iron core, a skeleton is provided on the outside of the static iron core and the moving iron core, a coil is wound on the skeleton, a sleeve is provided on the inside of the skeleton, and the moving iron core is located inside the sleeve; the front end of the shell is connected to the valve seat, and the rear end is connected to the connector, the piston, static iron core, coil, skeleton, moving iron core, return spring and other components are sealed inside the shell, the joint of the shell and the connector is connected through a tail shell, and a terminal electrically connected to the coil is provided in the connector; It also includes a guide structure, which includes a grid ring and a guide ring. A piston cavity is provided at the end of the static iron core, one end of the piston is slidably connected in the piston cavity, a first concave ring is provided on the inner wall of the piston cavity, the outer side of the grid ring is fixedly connected to the first concave ring, and the inner ring is slidably sealed with the piston; the guide ring is arranged between the push rod shaft and the static iron core, a second concave ring is provided on the inner wall of the axial hole of the static iron core, the outer side of the guide ring is embedded in the second concave ring and is fixedly connected to the static iron core, the inner side of the guide ring is slidably connected to the push rod shaft, and the push rod shaft is clearance-matched with other parts of the axial hole of the static iron core.

[0007] The piston and the moving iron core are fixedly connected to the push rod shaft. At the same time, a grid ring and a guide ring are added in the axial direction. During the axial movement, the grid ring guides the piston, and the guide ring guides the push rod shaft, forming two-point support in the axial direction to ensure concentricity and avoid tilting and jamming during the movement of the axis. At the same time, the push rod shaft is supported by the guide ring, which reduces the contact area between the push rod shaft and the shaft hole of the static iron core. The combination of the guide ring and the grid ring has sliding sealing, low friction resistance and guiding properties.

[0008] Furthermore, it also includes a special-shaped sealing gasket, the two ends of the inner ring of the special-shaped sealing gasket are respectively provided with a first ring wall and a second ring wall, an annular groove is formed between the first ring wall and the second ring wall, a convex ring is provided on the outer wall of the front end of the piston, the special-shaped sealing gasket is sleeved on the periphery of the front end of the piston, the convex ring is embedded in the annular groove, and the special-shaped sealing gasket is positioned by the ring groove to prevent it from falling off the piston; a sealing lip opening outward is provided on the first ring wall close to the inner ring side, and an axially extending first air hole is provided on the valve seat opposite to the first ring wall, and the inner cavity of the valve seat A second air hole is provided on the side wall, and there are multiple second air holes, which are evenly distributed along the circumference of the side wall of the inner cavity. A raised first rib is provided on the edge of the first air hole facing the first ring wall, and a second rib opposite to the first rib is provided on the convex ring end face of the piston, and the outer diameters of the first rib and the second rib are the same; when the valve is closed, the valve seat fits tightly against the special-shaped sealing gasket, and the first rib and the second rib are both pressed into the first ring wall of the special-shaped sealing gasket, and the sealing lip is located on the inner side of the inner circle of the first rib, that is, the outer diameter of the sealing lip is smaller than the outer diameter of the rib, and it fits tightly against the side wall of the piston under pressure.

[0009] A plurality of second air holes are provided on the circumferential side of the side wall of the valve seat. When the valve is closed, the valve seat fits tightly against the special-shaped sealing gasket, and the first air hole and the second air hole are disconnected. When the valve is opened, the valve seat is separated from the special-shaped sealing gasket, and the first air hole and the second air hole are connected. Among them, the special-shaped sealing lip fits more tightly against the side wall of the piston under pressure; the first rib and the second rib are on the same line, and are compressed with the special-shaped sealing gasket to isolate the leakage channel; the sealing gasket adopts a brand-new design, and when the power is turned on and closed, the sealing lip design and the rib design of the valve seat achieve high sealing performance; the second ring wall is used as a silencer pad, which is set at the piston, and the working temperature is not high. The second ring wall and the sealing gasket are integrated into one design, which reduces the cost. When the solenoid valve is opened, it collides with the static iron core, plays the role of a silencer pad, effectively reduces noise, and an exhaust channel is also provided on the second ring wall for balancing the air pressure.

[0010] Furthermore, due to the high working pressure, the electromagnetic force in the valve closing state is very large. Therefore, in order to reduce the valve closing electromagnetic force, the piston is provided with a plurality of through holes along the radial direction for connecting the piston cavity with the inner cavity of the valve seat. The piston is provided with a through hole axially to achieve pressure balance on both sides of the piston and reduce the closing electromagnetic force.

[0011] Furthermore, since the existing solenoid valve has a long response time, the reset spring adopts a variable pitch spring. The variable pitch spring has a small spring stiffness at the beginning, and the spring deforms quickly when the power is turned on to close the valve, which can shorten the response time; when the power is turned off to open the valve, the spring recovers from the compressed state, and its initial stiffness is large, so the response time of the power-off valve opening is short.

[0012] Furthermore, an annular magnetic conductive plate is provided on the outer side of the sleeve.

[0013] Furthermore, it also includes a spring positioning structure, which includes a first spring cavity arranged on the static iron core and a second spring cavity arranged on the moving iron core, and the first spring cavity and the second spring cavity are arranged opposite to each other, and one end of the return spring is arranged in the first spring cavity, and the other end is arranged in the second spring cavity.

[0014] Furthermore, it also includes a skeleton positioning mechanism, which includes a plurality of small protrusions arranged on the end face of the skeleton facing the static iron core, and the small protrusions can be plastically deformed, and the other side of the skeleton is tightly attached to the inner surface of the shell. When the static iron core fits the step surface of the shell, the static iron core squeezes the small protrusions to plastic deformation to ensure the positioning of the skeleton.

[0015] Furthermore, it also includes a sleeve positioning mechanism, the sleeve positioning mechanism includes a first step surface arranged on the outside of the static iron core, and a second step surface arranged on the frame, and the first step surface and the second step surface are opposite, and the end of the sleeve is provided with a bending portion that cooperates with the first step surface and the second step surface, and when assembled, the bending of the end of the sleeve is limited between the first step surface and the second step surface. The step surface of the frame and the step surface of the iron core limit the sleeve within a certain range, ensuring that the moving iron core will not contact the bottom of the sleeve when the power is turned on after being turned off.

[0016] Furthermore, it also includes an adjusting screw, which is threadedly connected to the side of the piston facing the valve seat. By adding the screw, the length of the push rod shaft can be adjusted, which is suitable for the product development stage and saves costs.

[0017] The beneficial effects of the present invention are: (1) The moving iron core, push rod shaft and piston are all fixedly connected, and a guide ring is added to ensure the center and prevent the moving iron core or push rod shaft from tilting and getting stuck.

[0018] (2) The combination of Gly ring and guide ring has both sliding sealing and low friction resistance as well as guiding properties.

[0019] (3) New gasket design: When the power is on and closed, the sealing lip design and the rib design of the gasket seat achieve high sealing performance.

[0020] (4) The silencer structure is set at the piston, and the working temperature is not high; and the integrated design of the silencer pad and the sealing pad reduces costs.

[0021] (5) The variable pitch spring is used, and the spring stiffness is smaller when the power is turned on to close the valve; the spring stiffness is larger when the power is turned off to open the valve, shortening the response time.

[0022] (6) A through hole is opened in the axial direction of the piston to achieve pressure balance and reduce the closing electromagnetic force. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 It is a three-dimensional structural schematic diagram of the solenoid valve of the present invention.

[0025] Figure 2 It is a schematic diagram of the cross-sectional structure of the solenoid valve (without the adjusting screw).

[0026] Figure 3 It is a schematic diagram of the cross-sectional structure of the static iron core.

[0027] Figure 4 It is a structural schematic diagram of a special-shaped sealing gasket.

[0028] Figure 5 It is a schematic diagram of the cross-sectional structure of a special-shaped sealing gasket.

[0029] Figure 6 yes Figure 2 Schematic diagram of the enlarged structure at point A in the middle.

[0030] Figure 7 yes Figure 2 Schematic diagram of the enlarged structure at point B in the middle.

[0031] Figure 8 It is a schematic diagram of the skeleton structure.

[0032] Fig. 9 It is a schematic diagram of the cross-sectional structure of the solenoid valve of another embodiment (with an additional adjusting screw).

[0033] In the figure: 1, valve seat, 1.1, first air hole, 1.2, second air hole, 1.3, first rib, 2, piston, 2.1, through hole, 2.2, convex ring, 2.3, second rib, 3, static iron core, 3.1, shaft hole, 3.2, piston cavity, 3.3, first concave ring, 3.4, second concave ring, 3.5, first spring cavity, 3.6, limit groove, 3.7, first step surface, 4, shell, 5, coil, 6, skeleton, 6.1, small protrusion, 6 .2. Second step surface, 7. Tail shell, 8. Special-shaped sealing gasket, 8.1. First ring wall, 8.2. Second ring wall, 8.3. Annular groove, 8.4. Sealing lip, 8.5. Exhaust channel, 9. Adjusting screw, 10. Gly ring, 11. Guide ring, 12. Push rod shaft, 13. Return spring, 14. Sleeve, 14.1. Bending part, 15. Moving iron core, 15.1. Second spring chamber, 16. Magnetic plate, 17. Terminal, 18. Connector. DETAILED DESCRIPTION

[0034] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention, and directions and references (e.g., up, down, left, right, etc.) may only be used to help describe the features in the drawings. Therefore, the following specific embodiments are not to be taken in a limiting sense, and the scope of the subject matter claimed is limited only by the attached claims and their equivalents. Embodiment 1

[0035] like Figure 1 and Figure 2As shown, a solenoid valve of the present invention comprises a housing 4, a static iron core 3 is fixedly connected in the housing 4, a push rod shaft 12 axially passes through the shaft hole 3.1 of the static iron core 3, and is slidably connected in the shaft hole 3.1 thereof, the front end of the push rod shaft 12 is connected to the piston 2, and the rear end is connected to the moving iron core 15, a reset spring 13 is sleeved on the push rod shaft 12, and is located between the static iron core 3 and the moving iron core 15, and the reset spring 13 adopts a variable pitch spring. The variable pitch spring has a small spring stiffness at the beginning, and when the power is turned on to close the valve, the spring deforms quickly, which can shorten the response time. When the power is turned off to open the valve, the spring recovers from the compressed state, and its initial stiffness is large. Therefore, the response time of the valve opening after the power is turned off is short. In order to ensure the reliable connection of the return spring 13, a spring positioning structure is also included, which includes a first spring cavity 3.5 arranged on the static iron core 3 and a second spring cavity 15.1 arranged on the moving iron core 15, and the first spring cavity 3.5 and the second spring cavity 15.1 are arranged oppositely, and one end of the return spring 13 is arranged in the first spring cavity 3.5, and the other end is arranged in the second spring cavity 15.1. A skeleton 6 is arranged on the outside of the static iron core 3 and the moving iron core 15, and a coil 5 is wound on the skeleton 6. A sleeve 14 is arranged on the inside of the skeleton 6, and the moving iron core 15 is located inside the sleeve 14; an annular magnetic conductive plate 16 is also arranged on the outside of the sleeve 14; the front end of the housing 4 is connected to the valve seat 1, and the rear end is connected to the connector 18, so that the piston 2, the static iron core 3, the coil 5, the skeleton 6, the moving iron core 15, the return spring 13 and other components are sealed inside the housing 4, and the joint between the housing 4 and the connector 18 is connected through the tail shell 7, and the connector 18 is provided with a terminal 17 electrically connected to the coil 5. The coil 5, the magnetic conductive plate 16 and the connector 18 can be implemented by the following two schemes: scheme 1: the connector 18 is provided with a buckle, and after the connector 18 is buckled with the frame 6, the winding is carried out, and the enameled wire lead is wound around the terminal 17 embedded in the connector 18, and connected by resistance welding or soldering, and then the terminal 17 is bent into the setting groove of the connector 18 to prevent the terminal 17 from contacting the shell; scheme 2: using Siameze terminals (enameled wire piercing terminals), firstly, the frame 6 is wound separately, the Siameze terminals are pressed out and pierce the enameled layer to achieve electrical connection, and then the magnetic conductive plate 16 and the connector 18 are assembled, and the embedded terminal of the connector 18 is inserted into the Siameze.

[0036] like Figure 2 and Figure 3As shown, in order to avoid axial movement jamming, it also includes a guiding structure, which includes a grid ring 10 and a guide ring 11. The left end of the static iron core 3 is provided with a piston cavity 3.2, and the right end is provided with a limit groove 3.6, and the limit groove 3.6 is used to position and limit the moving iron core 15; the right end of the piston 2 is slidably connected in the piston cavity 3.2, and a first concave ring 3.3 is provided on the inner wall of the piston cavity 3.2. The outer side of the grid ring 10 is fixedly connected to the first concave ring 3.3, and the inner ring is slidably sealed with the piston 2; the guide ring 11 is arranged between the push rod shaft 12 and the static iron core 3, and a second concave ring 3.4 is provided on the inner wall of the axial hole 3.1 of the static iron core 3, and the outer side of the guide ring 11 is embedded in the second concave ring 3.4 and is fixedly connected to the static iron core 3, and the inner side of the guide ring 11 is slidably connected to the push rod shaft 12, and the push rod shaft 12 is gap-matched with other parts of the axial hole 3.1 of the static iron core 3. The piston 2 and the moving iron core 15 are fixedly connected to the push rod shaft 12. At the same time, a grid ring 10 (as a sliding sealing ring) and a guide ring 11 are added in the axial direction. During the axial movement, the grid ring 10 guides the piston 2, and the guide ring 11 guides the push rod shaft 12, forming two-point support in the axial direction to ensure concentricity and avoid tilting and jamming during the movement of the axis. At the same time, the push rod shaft 12 is supported by the guide ring 11, which reduces the contact area between the push rod shaft 12 and the axial hole 3.1 of the static iron core 3. The combination of the guide ring 11 and the grid ring 10 has sliding sealing, low friction resistance and guiding properties.

[0037] like Figure 4-Figure 6 As shown, in order to realize the opening and closing of the inlet and outlet of the valve seat 1 and ensure the sealing performance, a special-shaped sealing gasket 8 (see Figure 6 The green part in the middle), the two ends of the inner ring of the special-shaped sealing gasket 8 are respectively provided with a first ring wall 8.1 and a second ring wall 8.2, and an annular groove 8.3 is formed between the first ring wall 8.1 and the second ring wall 8.2. A convex ring 2.2 is provided on the outer wall of the front end of the piston 2, and the special-shaped sealing gasket 8 is sleeved on the periphery of the front end of the piston 2. The convex ring 2.2 is embedded in the annular groove 8.3, and the special-shaped sealing gasket 8 is positioned by the ring groove to prevent it from falling off the piston 2; the first ring wall 8.1 is provided with a sealing lip 8.4 opening outward on the side close to the inner ring, and the valve seat 1 opposite to the first ring wall 8.1 is provided with an axially extending first air hole 1.1, and the inner cavity side wall of the valve seat 1 is provided with a second air hole 1.2, and the second air hole 1.2 is multiple and evenly distributed along the circumferential direction of the side wall of the inner cavity, and a raised first rib 1.3 is provided on the edge of the first air hole 1.1 facing the first ring wall 8.1 ( Figure 6 The end surface of the convex ring 2.2 of the piston 2 is provided with a second rib 2.3 (which is opposite to the first rib 1.3) Figure 6(shown by the blue line in the middle), the outer diameters of the first rib 1.3 and the second rib 2.3 are the same, that is, the first rib 1.3 and the second rib 2.3 are on the same line, and are under pressure with the special-shaped sealing gasket 8 to isolate the leakage channel; when the valve is closed, the valve seat 1 is tightly fitted with the special-shaped sealing gasket 8, and the first rib 1.3 and the second rib 2.3 are both pressed into the first ring wall 8.1 of the special-shaped sealing gasket 8, and the sealing lip 8.4 is located on the inner side of the inner ring of the first rib 1.3, that is, the outer diameter of the sealing lip 8.4 is smaller than the outer diameter of the rib, and is tightly fitted with the side wall of the piston 2 under pressure. The second ring wall 8.2 is used as a silencer and is arranged at the piston 2. The working temperature is not high, and the second ring wall 8.2 is integrated with the sealing gasket to reduce the cost. When the solenoid valve is opened, it collides with the static iron core 3, plays the role of a silencer, effectively reduces noise, and an exhaust channel 8.5 is also provided on the second ring wall 8.2 to balance the air pressure.

[0038] like Figure 6 As shown, due to the high working pressure, the electromagnetic force in the valve closing state is very large. Therefore, in order to reduce the valve closing electromagnetic force, the piston 2 is provided with a plurality of through holes 2.1 in the radial direction for connecting the piston cavity 3.2 with the inner cavity of the valve seat 1. The piston 2 is provided with a through hole 2.1 in the axial direction to achieve pressure balance on both sides of the piston 2 and reduce the closing electromagnetic force.

[0039] like Figure 7 and Figure 8 As shown, it also includes a frame 6 positioning mechanism and a sleeve 14 positioning mechanism, wherein the frame 6 positioning mechanism includes a plurality of small protrusions 6.1 ( Figure 7 The green part in the middle), and the small protrusion 6.1 can be plastically deformed, and the other side of the skeleton 6 is tightly attached to the inner surface of the shell 4. When the static iron core 3 fits the step surface of the shell 4, the static iron core 3 squeezes the small protrusion 6.1 to plastic deformation to ensure the positioning of the skeleton 6. The sleeve 14 positioning mechanism includes a first step surface 3.7 arranged on the outside of the static iron core 3, and a second step surface 6.2 arranged on the skeleton 6, and the first step surface 3.7 and the second step surface 6.2 are opposite, and the end of the sleeve 14 is provided with a bending portion 14.1 that cooperates with the first step surface 3.7 and the second step surface 6.2. During assembly, the bending of the end of the sleeve 14 is limited between the first step surface 3.7 and the second step surface 6.2. The step surface of the skeleton 6 and the step surface of the iron core limit the sleeve 14 to a certain range to ensure that the moving iron core 15 will not contact the bottom of the sleeve 14 when the power is turned on after being turned off. Embodiment 2

[0040] like Fig. 9 As shown, the difference between this embodiment and the first embodiment is that an adjusting screw 9 is added, and the adjusting screw 9 is threadedly connected to the side of the piston 2 facing the valve seat 1. The additional screw can adjust the length of the push rod shaft 12, which is suitable for the product development stage and saves costs.

[0041] Working principle: The coil 5 is energized to generate a magnetic field, and the moving iron core 15 has polarity after being magnetized. The energized coil 5 has polarity (solenoid force), and the static iron core 3 is magnetized with polarity (surface force). Opposites attract each other, and the moving iron core 15 drives the push rod shaft 12 and the piston 2 to overcome the elastic force of the reset spring 13 and move toward the valve seat 1, squeezing the special-shaped sealing gasket 8 to achieve sealing; when the coil 5 is turned off, the electromagnetic magnetism disappears, and the reset spring 13 drives the moving iron core 15 to reset under the action of the elastic force, and the valve port is opened, so that the first air hole 1.1 and the second air hole 1.2 are connected. The height of the valve port opening determines the flow rate, realizing the design of the proportional valve to meet the needs of different flow rates.

[0042] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the scope of the present invention through the above description. The technical scope of this invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A solenoid valve, characterized in that: It comprises a shell, a static iron core is fixedly connected in the shell, a push rod shaft axially passes through the shaft hole of the static iron core and is slidably connected in the shaft hole, the front end of the push rod shaft is connected to the piston, and the rear end is connected to the moving iron core, a return spring is sleeved on the push rod shaft and is located between the static iron core and the moving iron core, a skeleton is provided on the outside of the static iron core and the moving iron core, a coil is wound on the skeleton, a sleeve is provided on the inside of the skeleton, and the moving iron core is located inside the sleeve; the front end of the shell is connected to the valve seat, and the rear end is connected to the connector, the joint of the shell and the connector is connected through a tail shell, and a terminal electrically connected to the coil is provided in the connector; It also includes a guide structure, which includes a grid ring and a guide ring. A piston cavity is provided at the end of the static iron core, one end of the piston is slidably connected in the piston cavity, a first concave ring is provided on the inner wall of the piston cavity, the outer side of the grid ring is fixedly connected to the first concave ring, and the inner ring is slidably sealed with the piston; the guide ring is arranged between the push rod shaft and the static iron core, a second concave ring is provided on the inner wall of the axial hole of the static iron core, the outer side of the guide ring is embedded in the second concave ring and is fixedly connected to the static iron core, the inner side of the guide ring is slidably connected to the push rod shaft, and the push rod shaft is clearance-matched with other parts of the axial hole of the static iron core.

2. The solenoid valve according to claim 1, characterized in that: It also includes a special-shaped sealing gasket, wherein the two ends of the inner ring of the special-shaped sealing gasket are respectively provided with a first ring wall and a second ring wall, an annular groove is formed between the first ring wall and the second ring wall, a convex ring is provided on the outer wall of the front end of the piston, the special-shaped sealing gasket is sleeved on the periphery of the front end of the piston, and the convex ring is embedded in the annular groove, a sealing lip opening outward is provided on the side of the first ring wall close to the inner ring, an axially extending first air hole is provided on the valve seat opposite to the first ring wall, a second air hole is provided on the inner cavity side wall of the valve seat, a raised first rib is provided on the edge of the first air hole facing the first ring wall, and a second rib opposite to the first rib is provided on the convex ring end face of the piston; when the valve is closed, the valve seat is tightly fitted with the special-shaped sealing gasket, and the first rib and the second rib are both pressed into the first ring wall of the special-shaped sealing gasket, the sealing lip is located on the inner side of the inner ring of the first rib, and is tightly fitted with the side wall of the piston under pressure.

3. The solenoid valve according to claim 1, characterized in that: The piston is provided with a plurality of through holes along the radial direction for connecting the piston cavity with the inner cavity of the valve seat.

4. The solenoid valve according to claim 1, characterized in that: The return spring is a variable pitch spring.

5. The solenoid valve according to claim 1, characterized in that: An annular magnetic conductive plate is also arranged on the outer side of the sleeve.

6. The solenoid valve according to claim 1, characterized in that: It also includes a spring positioning structure, which includes a first spring cavity arranged on the static iron core and a second spring cavity arranged on the moving iron core, and the first spring cavity and the second spring cavity are arranged opposite to each other, and one end of the return spring is arranged in the first spring cavity, and the other end is arranged in the second spring cavity.

7. The solenoid valve according to claim 1, characterized in that: It also includes a skeleton positioning mechanism, which includes a plurality of small protrusions arranged on the end face of the skeleton facing the static iron core, and the small protrusions can be plastically deformed, and the other side of the skeleton is tightly attached to the inner surface of the shell.

8. The solenoid valve according to claim 1, characterized in that: It also includes a sleeve positioning mechanism, which includes a first step surface arranged on the outside of the static iron core, and a second step surface arranged on the frame, and the first step surface and the second step surface are opposite to each other. The end of the sleeve is provided with a bending portion that cooperates with the first step surface and the second step surface. During assembly, the bending of the end of the sleeve is limited between the first step surface and the second step surface.

9. The solenoid valve according to claim 1, characterized in that: The utility model also comprises an adjusting screw, wherein the adjusting screw is threadedly connected to a side of the piston facing the valve seat.

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