A pilot solenoid valve

Abstract

The present invention relates to the field of solenoid valves, and in particular to a pilot-operated solenoid valve. The solenoid valve comprises a main valve and a pilot valve, wherein the main valve comprises a main valve body and a main valve core, and the pilot valve comprises a pilot valve body, a moving iron core, a coil and a compensating damping assembly. The base of the pilot valve body is provided with a connecting hole connecting the interior of the pilot valve body and the upper cavity of the main valve body, and a pilot hole connecting the interior of the pilot valve body and the liquid outlet of the main valve body, and the compensating damping assembly can move with the moving iron core to be inserted into or pulled out of the connecting hole. When the solenoid valve is opened or closed, the present invention buffers the braking force of the moving iron core by moving the compensating damping assembly in the connecting hole, thereby avoiding damage to the valve body structure, and at the same time changes the volume of the liquid filling in the upper cavity of the main valve body by moving the compensating assembly in the connecting hole, thereby improving the response speed of the solenoid valve.

Description

Technical Field

[0001] The invention relates to the field of solenoid valves, and in particular to a pilot-operated solenoid valve. Background Art

[0002] Solenoid valve is an industrial equipment controlled by electromagnetics. It is an automatic basic component used to control fluids. It belongs to an actuator and is not limited to hydraulics and pneumatics. It is used in industrial control systems to adjust the direction, flow, speed and other parameters of the medium. Solenoid valves can be used with different circuits to achieve the desired control, and the accuracy and flexibility of the control can be guaranteed. Solenoid valves are divided into three categories in principle: direct-acting solenoid valves, step-by-step direct-acting solenoid valves, and pilot-operated solenoid valves. The operating principle of the pilot solenoid valve is as follows: when the power is turned on, the electromagnetic force opens the pilot hole, the pressure in the upper chamber drops rapidly, and a pressure difference with a low top and a high bottom is formed around the closing part. The fluid pressure pushes the closing part to move upward and the valve opens; when the power is turned off, the spring force closes the pilot hole, and the inlet pressure quickly forms a pressure difference with a low bottom and a high top around the closing valve part through the bypass hole. The fluid pressure pushes the closing part to move downward, closing the valve, and the pressure in the upper chamber of the solenoid valve increases. The fluid pressure pressurizes the main valve core, and the seal is better. The upper limit of the fluid pressure range of the pilot solenoid valve is relatively high, and it can be installed arbitrarily as long as the fluid pressure difference conditions are met. Pilot solenoid valves are usually selected in large-diameter scenarios.

[0003] The existing pilot solenoid valve has the following problems when in use:

[0004] 1. The response speed when opening or closing is not as fast as that of direct-acting solenoid valve;

[0005] 2. The pilot valve core will go through acceleration and braking stages when in motion. Braking is often achieved by hitting the limit at the extreme position, which is easy to generate noise and damage the internal structure of the valve body. In severe cases, it will lead to problems such as poor sealing and leakage.

[0006] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0007] In view of the deficiencies of the prior art, the present invention proposes a pilot-operated solenoid valve to solve the problems that the existing pilot-operated solenoid valve has a slow opening and closing response speed and the internal structure of the valve body is easily damaged.

[0008] A pilot-operated solenoid valve of the present invention adopts the following technical solution: it comprises a main valve and a pilot valve;

[0009] The main valve includes:

[0010] The main valve body has an upper cavity and a lower cavity, and the left and right ends of the lower cavity of the main valve body are respectively provided with a liquid outlet and a liquid inlet;

[0011] The main valve core is arranged in the upper cavity and can slide elastically in the up-down direction. The main valve core is used to connect or block the liquid inlet and the liquid outlet. The main valve core is initially located at the lower limit position to block the liquid inlet and the liquid outlet. A damping hole that passes through from top to bottom is arranged on the main valve core at the position corresponding to the liquid inlet, and the liquid in the liquid inlet can flow into the upper cavity through the damping hole.

[0012] The pilot valve includes:

[0013] The pilot valve body is arranged at the upper end of the main valve body and the base of the pilot valve body blocks the upper cavity opening of the main valve body. The base of the pilot valve body is provided with a connecting hole connecting the interior of the pilot valve body and the upper cavity of the main valve body; the base of the pilot valve body is provided with a pilot hole connecting the interior of the pilot valve body and the liquid outlet;

[0014] A moving iron core is arranged inside the pilot valve body and can slide elastically in the up-down direction;

[0015] A compensating damping component is arranged on the moving iron core and corresponds to the connecting hole. The compensating damping component can move with the moving iron core to be inserted into or withdrawn from the connecting hole, thereby connecting or blocking the inner cavity of the pilot valve body and the upper cavity of the main valve body;

[0016] The coil is arranged on the pilot valve body and is used to control the movement of the moving iron core. In the initial state, the moving iron core is at the lower limit position to block the pilot hole and the connecting hole.

[0017] Optionally, a first elastic member is connected between the top of the moving iron core and the inner top of the pilot valve body.

[0018] Optionally, a second elastic member is provided between the top of the main valve core and the base of the pilot valve body.

[0019] Optionally, a cushion block is provided at the bottom of the moving iron core.

[0020] Optionally, a first control flow channel is provided on the base of the pilot valve body, the first control flow channel is connected to the pilot hole, a second control flow channel is provided on the side wall of the main valve body, the second control flow channel is connected to the liquid outlet, and the first control flow channel is connected to the second control flow channel.

[0021] Optionally, the compensating shock-absorbing assembly includes a pull rod, an inner cylinder and an outer cylinder;

[0022] The pull rod is arranged at the bottom of the moving iron core;

[0023] The inner tube is coaxially sleeved on the outside of the pull rod, and the inner tube can slide up and down relative to the pull rod along the axis of the pull rod without being separated from the pull rod;

[0024] The outer cylinder is coaxially sleeved on the outside of the inner cylinder, and the outer cylinder can be inserted into the communicating hole. The bottom peripheral wall of the communicating hole is provided with a card slot, and the peripheral wall of the outer cylinder is provided with two opposite square holes. The lower end of the inner cylinder is provided with an inner cavity, and two pins are provided in the inner cavity. The two pins correspond to the square holes one by one and are slidably arranged in the corresponding square holes. A third elastic member is connected between the two pins, and the third elastic member makes the two pins tend to move away from each other. Initially, the outer ends of the two pins extend out of the square holes and are located in the card slot.

[0025] The inner cavity of the inner tube is located on both side walls of the marbles, and two inclined grooves are arranged symmetrically on the same side wall, and the lower ends of the two inclined grooves are close to each other and the upper ends are far away from each other. Both sides of the marbles are provided with protrusions, which are arranged in the inclined grooves one by one and can slide in the corresponding inclined grooves.

[0026] Optionally, the two pins are connected via a connecting rod, the pins can slide relative to the connecting rod, and the third elastic member is sleeved on the connecting rod.

[0027] Optionally, the third elastic member is a spring.

[0028] Optionally, a pull plate is provided at the bottom of the pull rod, the diameter of the pull plate is larger than the diameter of the pull rod, and a retaining ring is provided at the top of the inner tube, and the retaining ring can stop the pull plate after contacting the pull plate.

[0029] Optionally, the pull rod is threadedly connected to the moving iron core.

[0030] The beneficial effects of the present invention are as follows: a pilot-operated solenoid valve of the present invention is provided with a connecting hole on the base of the pilot valve body, and a compensating damping assembly is provided at the lower end of the moving iron core. When the solenoid valve is opened or closed, the energy required for braking the moving iron core is consumed by the action of withdrawing or inserting the compensating damping assembly into the connecting hole, thereby avoiding energy waste and damage to the valve body structure. Furthermore, when the solenoid valve is closed, the compensating damping assembly is inserted into the connecting hole so that the volume of the upper cavity of the main valve body is gradually compressed, thereby causing the pressure in the upper cavity of the main valve body to increase rapidly, thereby accelerating the response speed of the main valve core to be pressed downward; similarly, when the solenoid valve is opened, the damping assembly is withdrawn from the connecting hole so that the volume of the upper cavity of the main valve body is gradually increased, thereby causing negative pressure to be generated in the upper cavity of the main valve body, thereby accelerating the response speed of the main valve core to be lifted upward. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1It is a schematic diagram of the overall structure of a pilot-operated solenoid valve of the present invention;

[0033] Figure 2 It is a cutaway perspective view of the pilot valve in the present invention;

[0034] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0035] Figure 4 This is a schematic diagram of an open state of a pilot-operated solenoid valve of the present invention;

[0036] Figure 5 This is a schematic diagram of a pilot-operated solenoid valve in a closed state according to the present invention;

[0037] Figure 6 It is a structural schematic diagram of a pilot solenoid valve in the prior art.

[0038] In the figure:

[0039] 110, pilot valve body; 111, coil; 112, communicating hole; 113, slot; 114, pilot hole; 115, first control flow channel; 120, moving iron core; 121, cushion block; 130, first elastic member; 150, compensation damping assembly; 151, pull rod; 1511, pull plate; 152, inner tube; 1521, inclined groove; 153, outer tube; 1531, square hole; 154, marble; 155, third elastic member;

[0040] 210, main valve body; 211, liquid inlet; 212, liquid outlet; 213, second control flow channel; 220, main valve core; 221, damping hole; 230, second elastic member;

[0041] 5. Pressure relief hole; 6. Electromagnet; 7. Pilot valve stem; 8. Piston; 9. Balance hole; 10. Valve body. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] like Figures 1 to 5 As shown, a pilot solenoid valve provided by an embodiment of the present invention includes a main valve and a pilot valve.

[0044] The main valve includes:

[0045] The main valve body 210 has an upper cavity and a lower cavity. The left and right ends of the lower cavity of the main valve body 210 are respectively provided with a liquid outlet 212 and a liquid inlet 211;

[0046] The main valve core 220 is arranged in the upper cavity and can slide elastically in the up-down direction. The main valve core 220 is used to connect or block the liquid inlet 211 and the liquid outlet 212. Initially, the main valve core 220 is located at the lower limit position to block the liquid inlet 211 and the liquid outlet 212. A damping hole 221 that passes through the main valve core 220 is arranged at a position corresponding to the liquid inlet 211. The liquid in the liquid inlet 211 can flow into the upper cavity through the damping hole 221.

[0047] The pilot valve includes:

[0048] The pilot valve body 110 is arranged at the upper end of the main valve body 210 and the base of the pilot valve body 110 blocks the upper cavity opening of the main valve body 210. The base of the pilot valve body 110 is provided with a connecting hole 112 connecting the interior of the pilot valve body 110 and the upper cavity of the main valve body 210; the base of the pilot valve body 110 is provided with a pilot hole 114 connecting the interior of the pilot valve body 110 and the liquid outlet 212;

[0049] The moving iron core 120 is disposed inside the pilot valve body 110 and can elastically slide in the up-down direction;

[0050] The compensating damping assembly 150 is disposed on the moving iron core 120 and corresponds to the connecting hole 112. The compensating damping assembly 150 can move with the moving iron core 120 to be inserted into or withdrawn from the connecting hole 112, thereby connecting or blocking the inner cavity of the pilot valve body 110 and the upper cavity of the main valve body 210;

[0051] The coil 111 is disposed on the pilot valve body 110 and is used to control the movement of the moving iron core 120 . In the initial state, the moving iron core 120 is at the lower limit position to block the pilot hole 114 and the connecting hole 112 .

[0052] Reference Figure 6 , Figure 6The internal structure of the pilot-operated two-position two-way solenoid valve in the prior art is given. Initially, the pilot valve stem 7 is at the lower limit position. The medium enters the valve body 10 from the direction of the arrow, and enters the upper cavity of the valve body 10 through the balance hole 9, and then enters the interior of the pilot valve. The pressure in the upper cavity of the valve body 10 increases, so that the piston 8 is at the lower limit position, the inlet and outlet of the valve body 10 are cut off, and the solenoid valve is in a closed state; when the valve needs to be opened, the electromagnet 6 is energized to control the pilot valve stem 7 to lift up, the pressure relief hole 5 of the pilot valve is opened, and the upper cavity of the valve body 10 is relieved. At this time, under the action of the medium pressure, the piston 8 is lifted, the inlet and outlet of the valve body 10 are connected, and the medium flows from the inlet to the outlet. When the valve needs to be closed, the electromagnet 6 is powered off, the pilot valve stem 7 is reset under the action of the spring, the pressure relief hole 5 is closed, and the piston 8 is reset under the action of the spring to block the inlet and outlet of the valve body 10. From the above, it can be seen that the pilot valve stem 7 of the pilot solenoid valve in the prior art will experience acceleration and braking stages when it is in action. The braking is achieved by hitting the limit at the extreme position, which makes a lot of noise. In addition, the limit at both ends of the iron core and the extreme position is easily damaged, resulting in poor sealing, leakage and other problems. In addition, when opening or closing the valve, due to the long liquid flow path, the response speed is not as good as that of the direct-acting solenoid valve.

[0053] The present invention sets a compensating damping assembly 150 at the lower end of the moving iron core 120 of the pilot valve. When the solenoid valve is opened or closed, the energy consumed by the braking of the moving iron core 120 is consumed by the action of withdrawing or inserting the compensating damping assembly 150 into the connecting hole 112, thereby avoiding energy waste and damage to the valve body structure. Furthermore, when the solenoid valve is closed, the compensating damping assembly 150 is inserted into the connecting hole 112, so that the volume of the upper cavity of the main valve body 210 is gradually compressed, thereby causing the pressure in the upper cavity of the main valve body 210 to increase rapidly, thereby accelerating the response speed of the main valve body 210 to press down; similarly, when the solenoid valve is opened, the damping assembly is withdrawn from the connecting hole 112, so that the volume of the upper cavity of the main valve body 210 is gradually increased, thereby causing negative pressure to be generated in the upper cavity of the main valve body 210, thereby accelerating the response speed of the main valve body 210 to lift up.

[0054] In a further embodiment, a first elastic member 130 is connected between the top of the moving iron core 120 and the inner top of the pilot valve body 110 to facilitate the movement and reset of the moving iron core 120. A groove is provided at the top of the moving iron core 120, and the first elastic member 130 is connected to the bottom of the groove, so that the space occupied by the first elastic member 130 can be reduced. A second elastic member 230 is provided between the top of the main valve core 220 and the base of the pilot valve body 110 to facilitate the movement and reset of the main valve core 220. The first elastic member 130 and the second elastic member 230 are preferably springs.

[0055] In a further embodiment, a cushion block 121 is disposed at the bottom of the moving iron core 120 , and the sealing effect of the moving iron core 120 on the pilot hole 114 can be improved by disposing the cushion block 121 .

[0056] Furthermore, in order to facilitate the connection between the pilot hole 114 and the liquid outlet 212, a first control channel 115 is provided on the base of the pilot valve body 110, and the first control channel 115 is connected to the pilot hole 114. A second control channel 213 is provided on the side wall of the main valve body 210, and the second control channel 213 is connected to the liquid outlet 212. The first control channel 115 and the second control channel 213 are connected.

[0057] In a further embodiment, the compensating shock absorbing assembly 150 includes a pull rod 151 , an inner cylinder 152 and an outer cylinder 153 .

[0058] The pull rod 151 is disposed at the bottom of the moving iron core 120 . As a preferred embodiment, the pull rod 151 is threadedly connected to the moving iron core 120 . The pull rod 151 is installed by threaded connection, which facilitates the maintenance and replacement of the pull rod 151 .

[0059] The inner cylinder 152 is coaxially sleeved on the outside of the pull rod 151, and the inner cylinder 152 can slide up and down relative to the pull rod 151 along the axis of the pull rod 151 without being separated from the pull rod 151; specifically, a pull plate 1511 is provided at the bottom of the pull rod 151, and the diameter of the pull plate 1511 is larger than the diameter of the pull rod 151, and a retaining ring is provided on the top of the inner cylinder 152, and the retaining ring can stop the pull plate 1511 after contacting with the pull plate 1511, so that the pull rod 151 and the inner cylinder 152 will not be separated from each other, and the pull rod 151 can drive the inner cylinder 152 to move upward.

[0060] The outer cylinder 153 is coaxially sleeved on the outside of the inner cylinder 152. The outer cylinder 153 can be inserted into the connecting hole 112. The bottom peripheral wall of the connecting hole 112 is provided with a card slot 113. The peripheral wall of the outer cylinder 153 is provided with two opposite square holes 1531. The lower end of the inner cylinder 152 is provided with an inner cavity. Two pins 154 are provided in the inner cavity. The two pins 154 correspond to the square holes 1531 one by one and are slidably arranged in the corresponding square holes 1531. A third elastic member 155 is connected between the two pins 154. The third elastic member 155 makes the two pins 154 tend to move away from each other. Initially, the outer ends of the two pins 154 extend out of the square holes 1531 and are located in the card slot 113. Preferably, the third elastic member 155 is a spring, more specifically a compression spring.

[0061] Two inclined grooves 1521 are provided on the two side walls of the inner cavity of the inner tube 152 on both sides of the ball 154. The two inclined grooves 1521 on the same side wall are symmetrically arranged, and the lower ends of the two inclined grooves 1521 are close to each other and the upper ends are far away from each other. Bumps are provided on both sides of the ball 154. The bumps are arranged in the inclined grooves 1521 one by one and can slide in the corresponding inclined grooves 1521.

[0062] In order to improve the reliability of the movement of the pin 154 and facilitate the installation of the third elastic member 155, the two pins 154 are connected by a connecting rod. The pin 154 can slide relative to the connecting rod, and the third elastic member 155 is sleeved on the connecting rod.

[0063] Taking liquid medium as an example, refer to Figure 1 , the liquid flows in the direction indicated by the arrow.

[0064] Reference Figure 5 In the normal state, the coil 111 is not energized, the moving iron core 120 is at the lower limit position under the elastic force of the first elastic member 130, the moving iron core 120 blocks the pilot hole 114, and the compensation damping assembly 150 blocks the connecting hole 112. In this way, the liquid in the liquid inlet 211 gradually enters the upper cavity of the main valve body 210 through the damping hole 221, and cannot continue to flow into the pilot valve. The upper cavity of the main valve body 210 cannot be depressurized, and the pressure gradually increases. The main valve body 210 is at the lower limit position under the liquid pressure and the elastic force of the second elastic member 230, and the liquid inlet 211 and the liquid outlet 212 are blocked. At this time, the solenoid valve is in a closed state.

[0065] When the solenoid valve needs to be opened, the coil 111 is energized, and the moving iron core 120 is lifted upward by the electromagnetic force to open the pilot hole 114. At the same time, the moving iron core 120 drives the pull rod 151 to move upward. After the pull rod 151 moves upward for a distance, the pull plate 1511 presses against the retaining ring on the upper edge of the inner tube 152. Thereafter, the pull rod 151 moves upward with the inner tube 152. Due to the limiting effect of the inclined groove 1521, the pin 154 compresses the third elastic member 155 and moves inward, and the pin 154 disengages from the slot 113. Subsequently, the outer tube 153 and the inner tube 152 move upward together until the outer tube 153 disengages from the connecting hole 112 and the connecting hole 112 opens. The liquid enters the pilot valve body 110 through the connecting hole 112 and enters the liquid outlet 212 through the pilot hole 114, the first control flow channel 115 and the second control flow channel 213. The upper cavity of the main valve body 210 is depressurized, the main valve body 210 is lifted, the liquid outlet 212 and the liquid inlet 211 are connected, and the valve is opened. Therefore, when opening and closing the valve, the braking force of the moving iron core 120 is buffered by the movement of the compensation damping component 150 in the connecting hole 112 to avoid damage to the internal structure of the valve body. At the same time, the volume of the liquid filling in the upper cavity of the main valve body 210 is changed by the movement of the compensation damping component 150 in the connecting hole 112, thereby improving the response speed of the solenoid valve.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A pilot-operated solenoid valve, characterized in that: Including main valve and pilot valve; The main valve includes: The main valve body has an upper cavity and a lower cavity, and the left and right ends of the lower cavity of the main valve body are respectively provided with a liquid outlet and a liquid inlet; The main valve core is arranged in the upper cavity and can slide elastically in the up-down direction. The main valve core is used to connect or block the liquid inlet and the liquid outlet. The main valve core is initially located at the lower limit position to block the liquid inlet and the liquid outlet. A damping hole that passes through from top to bottom is arranged on the main valve core at the position corresponding to the liquid inlet, and the liquid in the liquid inlet can flow into the upper cavity through the damping hole. The pilot valve includes: The pilot valve body is arranged at the upper end of the main valve body and the base of the pilot valve body blocks the upper cavity opening of the main valve body. The base of the pilot valve body is provided with a connecting hole connecting the interior of the pilot valve body and the upper cavity of the main valve body; the base of the pilot valve body is provided with a pilot hole connecting the interior of the pilot valve body and the liquid outlet; A moving iron core is arranged inside the pilot valve body and can slide elastically in the up-down direction; A compensating damping component is arranged on the moving iron core and corresponds to the connecting hole. The compensating damping component can move with the moving iron core to be inserted into or withdrawn from the connecting hole, thereby connecting or blocking the inner cavity of the pilot valve body and the upper cavity of the main valve body; The coil is arranged on the pilot valve body and is used to control the movement of the moving iron core. In the initial state, the moving iron core is at the lower limit position to block the pilot hole and the connecting hole; The compensating shock-absorbing assembly includes a pull rod, an inner cylinder and an outer cylinder; The pull rod is arranged at the bottom of the moving iron core; The inner tube is coaxially sleeved on the outside of the pull rod, and the inner tube can slide up and down relative to the pull rod along the axis of the pull rod without being separated from the pull rod; The outer cylinder is coaxially sleeved on the outside of the inner cylinder, and the outer cylinder can be inserted into the communicating hole. The bottom peripheral wall of the communicating hole is provided with a card slot, and the peripheral wall of the outer cylinder is provided with two opposite square holes. The lower end of the inner cylinder is provided with an inner cavity, and two pins are provided in the inner cavity. The two pins correspond to the square holes one by one and are slidably arranged in the corresponding square holes. A third elastic member is connected between the two pins, and the third elastic member makes the two pins tend to move away from each other. Initially, the outer ends of the two pins extend out of the square holes and are located in the card slot. The inner cavity of the inner tube is located on both side walls of the marbles, and two inclined grooves are arranged symmetrically on the same side wall, and the lower ends of the two inclined grooves are close to each other and the upper ends are far away from each other. Both sides of the marbles are provided with protrusions, which are arranged in the inclined grooves one by one and can slide in the corresponding inclined grooves.

2. A pilot-operated solenoid valve according to claim 1, characterized in that: A first elastic member is connected between the top of the moving iron core and the inner top of the pilot valve body.

3. A pilot-operated solenoid valve according to claim 1, characterized in that: A second elastic member is arranged between the top of the main valve core and the base of the pilot valve body.

4. A pilot-operated solenoid valve according to claim 1, characterized in that: A cushion block is arranged at the bottom of the moving iron core.

5. The pilot-operated solenoid valve according to claim 1, characterized in that: A first control flow channel is arranged on the base of the pilot valve body, the first control flow channel is connected to the pilot hole, a second control flow channel is arranged on the side wall of the main valve body, the second control flow channel is connected to the liquid outlet, and the first control flow channel is connected to the second control flow channel.

6. The pilot-operated solenoid valve according to claim 1, characterized in that: The two pins are connected via a connecting rod. The pins can slide relative to the connecting rod. The third elastic member is sleeved on the connecting rod.

7. The pilot-operated solenoid valve according to claim 1, characterized in that: The third elastic member is a spring.

8. The pilot-operated solenoid valve according to claim 1, characterized in that: A pull plate is arranged at the bottom of the pull rod, the diameter of the pull plate is larger than the diameter of the pull rod, and a retaining ring is arranged at the top of the inner tube, and the retaining ring can stop the pull plate after contacting the pull plate.

9. The pilot-operated solenoid valve according to claim 1, characterized in that: The pull rod is threadedly connected to the moving iron core.

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