A pilot valve plunger seal structure

Abstract

The application relates to the hydraulic technology field and discloses a pilot valve plunger sealing structure, which comprises a pilot valve body, a pilot valve plunger is slid in the interior of the pilot valve body, a plunger guide sleeve is arranged on the outer periphery of the pilot valve plunger, a main sealing piece is slid in the interior of one side of the plunger guide sleeve close to the pilot valve plunger, a check ring is abutted on one side of the main sealing piece away from the plunger guide sleeve, a plunger hole and a sealing hole are arranged in the interior of the pilot valve body, a valve core is arranged in the interior of the pilot valve body, and a metering spring and a return spring are arranged on the outer periphery of the valve core. In addition to the O-shaped sealing ring auxiliary static sealing and dynamic sealing, the sealing piece formed by the fixed sleeve, hydrogenated butyronitrile rubber with a special structure and the self-tight spring realizes static and dynamic sealing, the plunger sealing performance is improved through the multiple static sealing and dynamic sealing, and the possibility of hydraulic oil leakage is reduced.

Description

Technical Field

[0001] This invention relates to the field of hydraulic technology, specifically to a pilot valve plunger sealing structure. Background Technology

[0002] A pilot valve is a device that uses a small control signal (such as a hydraulic, pneumatic, or electrical signal) to guide and control the action of the main valve or the entire system. It is a key component in hydraulic and pneumatic systems. Through a pilot valve, a small signal can be amplified to a level sufficient to drive the main valve with a large flow rate or high pressure, thereby achieving precise control of the system. Its characteristics include rapid response, low energy consumption, compact structure, and suitability for high-precision control of complex systems. Pilot valves are widely used in industrial automation, construction machinery, hydraulic equipment, and pneumatic devices, such as the hydraulic systems of excavators, the pneumatic component control in factory automation, and various fluid control systems, significantly improving the control efficiency and stability of equipment. A pilot valve plunger seal is a device used to seal the gap between the pilot valve plunger and the valve body. By using high-pressure resistant and wear-resistant sealing materials (such as rubber, polyurethane, or metal), it ensures that the plunger does not leak during operation, while simultaneously guaranteeing the accurate flow path of the hydraulic or pneumatic medium. Its design not only withstands high-pressure environments but also reduces wear and extends service life, making it a key component for stable operation and sealing performance of the pilot valve. In hydraulic systems, the quality of the pilot valve plunger seal directly affects the system's performance; for example, the precise control of excavator boom and stick movements relies on the pilot valve. The plunger in the pilot valve moves frequently within the valve body. When hydraulic oil pushes the plunger through the pilot valve's control channel, poor sealing can lead to hydraulic oil leakage, causing unstable system pressure and resulting in weak or vibrating bucket lifting in the loader, affecting work efficiency and operational quality. Existing pilot valve plunger sealing structures exhibit low sealing reliability, are prone to leakage, and have short service life under high-pressure environments, failing to meet the technical requirements of long-term stable operation of hydraulic systems in construction machinery. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a pilot valve plunger sealing structure, which solves the problem that traditional seals, which only use O-ring rubber and skeleton seals, have a high risk of hydraulic oil leakage.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a pilot valve plunger sealing structure, comprising a pilot valve body, a pilot valve plunger sliding inside the pilot valve body, a plunger guide sleeve fitted around the outer periphery of the pilot valve plunger, a main sealing element sliding inside the plunger guide sleeve on the side near the pilot valve plunger, a retaining ring abutting the side of the main sealing element away from the plunger guide sleeve, a plunger hole and a sealing hole being formed inside the pilot valve body, a valve core being installed inside the pilot valve body, a metering spring and a return spring respectively fitted around the outer periphery of the valve core, a retaining pad abutting the end of the metering spring and the return spring near the pilot valve plunger, and an open retaining ring being installed around the outer periphery of the end of the pilot valve plunger near the valve core.

[0005] Preferably, a first O-ring is provided on the side of the plunger guide sleeve closest to the pilot valve plunger, and a second O-ring is provided on the side of the plunger guide sleeve furthest from the pilot valve plunger.

[0006] Preferably, the main seal includes a fixing sleeve disposed inside the plunger guide sleeve. The fixing sleeve is provided with hydrogenated nitrile rubber on the side near the pilot valve plunger. The side of the hydrogenated nitrile rubber near the pilot valve plunger is provided with a sealing upper lip and a sealing lower lip, respectively. The side of the hydrogenated nitrile rubber away from the pilot valve plunger is provided with a self-tightening spring.

[0007] Preferably, the plunger guide sleeve has an inner sealing groove, the first O-ring slides inside the inner sealing groove, the plunger guide sleeve has an outer sealing groove on its outer periphery, the second O-ring slides inside the outer sealing groove, the plunger guide sleeve has a static sealing groove in its middle part, and the fixed sleeve is slidably connected inside the static sealing groove.

[0008] Preferably, the valve core is slidably connected inside the pilot valve plunger, and the main seal is interference-fitted with the pilot valve plunger.

[0009] Preferably, the side of the open retaining ring near the pilot valve plunger abuts against the side of the retaining ring away from the main seal, and the side of the open retaining ring away from the pilot valve plunger abuts against the side of the retaining pad near the pilot valve plunger.

[0010] Preferably, the plunger guide sleeve is provided with a mounting plate on the outer periphery away from the pilot valve plunger, and the mounting plate is fixed to the outer periphery of the pilot valve body by fastening screws.

[0011] Preferably, the valve core is slidably connected to the middle of the retaining pad, and the side of the retaining pad away from the metering spring abuts against the end of the pilot valve plunger near the valve core.

[0012] This invention provides a pilot valve plunger sealing structure. It has the following beneficial effects:

[0013] 1. The pilot valve plunger is automatically reset by the return spring of the pilot valve body. When the pilot valve plunger moves up and down, the main seal slides more smoothly with the plunger surface, reducing the possibility of leakage and stabilizing the output pilot fluid pressure.

[0014] 2. This invention achieves a tight fit between the main seal and the pilot valve plunger. The main seal consists of a fixed sleeve, hydrogenated nitrile rubber, and a self-tightening spring, forming an integrated sealing assembly. The self-tightening spring wraps around the hydrogenated nitrile rubber, and the spring tension ensures a tighter fit between the main seal and the pilot valve plunger. Even when the oil temperature rises during operation, the self-tightening spring maintains an interference fit, preventing hydraulic oil leakage. Compared with traditional rubber seals, this invention provides a more reliable seal and a longer service life.

[0015] 3. The present invention has a first O-ring inside the plunger guide sleeve and a second O-ring outside the plunger guide sleeve. This not only seals the pilot valve plunger and the pilot valve body, but also positions and guides them, ensuring the concentricity accuracy of the pilot valve plunger and the sealing element, making the seal more reliable.

[0016] 4. This invention employs a multi-seal design, with the seal having multiple oil storage ring grooves, reducing the friction of the plunger, greatly improving the service life of the entire sealing structure, and significantly enhancing the performance of the pilot valve. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the main sealing element of the present invention;

[0019] Figure 3 This is a schematic diagram of the retaining ring of the present invention;

[0020] Figure 4 This is a schematic diagram of the plunger guide sleeve of the present invention;

[0021] Figure 5 This is a schematic diagram of the structure of the card pad of the present invention;

[0022] Figure 6 This is a schematic diagram of the pilot valve plunger assembly of the present invention.

[0023] The components are as follows: 1. Pilot valve plunger; 2. First O-ring; 3. Main seal; 4. Second O-ring; 5. Pilot valve body; 6. Return spring; 7. Valve core; 8. Metering spring; 9. Gasket; 10. Opening retaining ring; 11. Retaining ring; 12. Mounting plate; 13. Fastening screw; 14. Plunger guide sleeve; 15. Fixing sleeve; 16. Hydrogenated nitrile rubber; 17. Self-tightening spring; 18. Sealing lower lip; 19. Sealing upper lip; 20. Inner sealing groove; 21. Outer sealing groove; 22. Static sealing groove. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see the appendix Figure 1 This invention provides a pilot valve plunger sealing structure, including a pilot valve body 5, a pilot valve plunger 1 sliding inside the pilot valve body 5, a plunger guide sleeve 14 sleeved on the outer periphery of the pilot valve plunger 1, an mounting plate 12 disposed on the outer periphery of the plunger guide sleeve 14 away from the pilot valve plunger 1, the mounting plate 12 being fixed to the outer periphery of the pilot valve body 5 by fastening screws 13, a main sealing element 3 sliding inside the side of the plunger guide sleeve 14 near the pilot valve plunger 1, a plunger hole and a sealing hole being opened inside the pilot valve body 5, a valve core 7 being installed inside the pilot valve body 5, a metering spring 8 and a return spring 6 being respectively sleeved on the outer periphery of the valve core 7, and an open retaining ring 10 being installed on the outer periphery of the end of the pilot valve plunger 1 near the valve core 7.

[0026] In this invention, the pilot valve body 5 has a plunger hole and a sealing hole inside. The valve core 7, pilot valve plunger 1, return spring 6, and metering spring 8 are tightly fitted onto the retaining gasket 9. When the pilot valve plunger 1 is pressed, the retaining gasket 9 moves downward, thereby causing the valve core 7 to move downward. When the pilot valve plunger 1 is depressurized, the return spring 6 automatically resets. Therefore, the valve core 7 and metering spring 8 move up and down, providing a stable pressure output for the pilot valve. The sealing quality of the pilot valve plunger 1 directly affects the performance of the pilot valve. Please refer to the appendix. Figure 1 - Appendix Figure 2 The main sealing element 3 includes a fixing sleeve 15, which is disposed inside the plunger guide sleeve 14. A hydrogenated nitrile rubber 16 is provided on the side of the fixing sleeve 15 near the pilot valve plunger 1. A sealing upper lip 19 and a sealing lower lip 18 are respectively provided on the side of the hydrogenated nitrile rubber 16 near the pilot valve plunger 1. A self-tightening spring 17 is provided on the side of the hydrogenated nitrile rubber 16 away from the pilot valve plunger 1.

[0027] In this invention, the main sealing element 3 is an integral sealing element composed of a fixed sleeve 15, hydrogenated nitrile rubber 16, and a self-tightening spring 17. The upper part of the hydrogenated nitrile rubber 16 is provided with a wedge-shaped sealing upper lip 19, which is a raised structure. The middle section of the upper lip is provided with a clearance groove to reduce friction, making the pilot valve plunger 1 move up and down more smoothly. The sealing upper lip 19 acts as a static seal for liquid. The lower part is provided with a wedge-shaped sealing lower lip 18, which is a raised structure. The lower lip has an oil reservoir groove in the middle section to lubricate the dynamic seal of the pilot valve plunger 1 and reduce the friction of the mating surfaces. The main seal 3 is press-fitted with the plunger guide sleeve 14 and the pilot valve plunger 1. The self-tightening spring 17 is wrapped with hydrogenated nitrile rubber 16. The spring tension makes the main seal 3 fit more tightly with the pilot valve plunger 1. Even if the oil temperature rises during operation, the self-tightening spring 17 can always maintain the press-fit and prevent hydraulic oil leakage.

[0028] Please see the appendix Figure 1 and attached Figure 3 The main seal 3 has a retaining ring 11 on the side away from the plunger guide sleeve 14.

[0029] In this invention, the retaining ring 11 is a flanged structure with a flange. The flange face is positioned on the sealing hole shoulder seat inside the pilot valve body 5. The inner hole of the retaining ring 11 supports the main sealing element 3, ensuring a tight fit between the main sealing element 3 and the pilot valve plunger 1 and plunger guide sleeve 14, thus improving sealing accuracy. The plunger guide sleeve 14 presses tightly against the upper surface of the flange of the retaining ring 11, and the fixing sleeve 15 of the main sealing element 3 presses tightly against the upper end face of the retaining ring 11, resulting in a more secure fastening of the main sealing element 3 and a better sealing effect. Please refer to the appendix. Figure 1 and attached Figure 4 A first O-ring 2 is provided on the side of the plunger guide sleeve 14 near the pilot valve plunger 1, and a second O-ring 4 is provided on the side of the plunger guide sleeve 14 away from the pilot valve plunger 1. An inner sealing groove 20 is provided inside the plunger guide sleeve 14, and the first O-ring 2 slides inside the inner sealing groove 20. An outer sealing groove 21 is provided on the outer periphery of the plunger guide sleeve 14, and the second O-ring 4 slides inside the outer sealing groove 21. A static sealing groove 22 is provided in the middle of the plunger guide sleeve 14, and the fixed sleeve 15 is slidably connected inside the static sealing groove 22.

[0030] In this invention, the inner hole of the plunger guide sleeve 14 is provided with an inner sealing groove 20, in which a first O-ring 2 is installed and is press-fitted with the pilot valve plunger 1 for dynamic sealing. The outer surface of the plunger guide sleeve 14 is provided with an outer sealing groove 21, in which a second O-ring 4 is installed and is press-fitted with the sealing hole provided on the pilot valve body 5 for static sealing. The middle of the plunger guide sleeve 14 is provided with a static sealing groove 22, and the upper part of the main sealing element 3 extends into the static sealing groove 22, wherein the upper sealing lip 19 is press-fitted with the inner side of the static sealing groove 22 for static sealing.

[0031] Please see the appendix Figure 1 and attached Figure 5 The metering spring 8 and the return spring 6 are abutted by a retaining pad 9 at the end near the pilot valve plunger 1. The valve core 7 is slidably connected inside the pilot valve plunger 1. The main seal 3 is interference-fitted with the pilot valve plunger 1. The valve core 7 is slidably connected in the middle of the retaining pad 9. The side of the retaining pad 9 away from the metering spring 8 abuts against the end of the pilot valve plunger 1 near the valve core 7.

[0032] In this invention, the gasket 9 has an upper and lower groove structure. The upper groove positions the pilot valve plunger 1, and the lower groove positions the reset spring 6 and the metering spring 8. The gasket 9 has an elongated hole in the middle, through which the valve core 7 can move up and down. The metering spring 8 pushes the valve core 7 to move, outputting a stable pilot valve hydraulic pressure.

[0033] Please see the appendix Figure 1 and attached Figure 6 The side of the open retaining ring 10 closest to the pilot valve plunger 1 abuts against the side of the retaining ring 11 away from the main seal 3, and the side of the open retaining ring 10 away from the pilot valve plunger 1 abuts against the side of the retaining pad 9 closest to the pilot valve plunger 1.

[0034] In this invention, the pilot valve plunger 1 is provided with a limiting groove. The limiting groove is used to install the open retaining ring 10 to prevent the pilot valve plunger 1 from falling out. The outer diameter of the pilot valve plunger 1 is uniform, and a high-precision sealing surface can be obtained by honing process, which reduces processing costs and maximizes the sealing reliability.

[0035] Working principle: After the main seal 3, retaining ring 11, and plunger guide sleeve 14 are installed in the sealing hole of the pilot valve body 5, the plunger guide sleeve 14 is pressed with the mounting plate 12, and the mounting plate 12 is fastened to the pilot valve body 5 with the fastening screw 13, so that the inner cavity of the pilot valve body 5 forms a closed oil chamber. When the pilot valve plunger 1 moves up and down, under the action of the valve core 7, the return spring 6, and the metering spring 8, a stable pilot hydraulic pressure is output, realizing the function of the entire pilot valve plunger sealing structure and ensuring the excellent sealing performance of the pilot valve.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pilot valve plunger sealing structure, comprising a pilot valve body (5), characterized in that, A pilot valve plunger (1) slides inside the pilot valve body (5). A plunger guide sleeve (14) is fitted around the outer periphery of the pilot valve plunger (1). A main seal (3) slides inside the plunger guide sleeve (14) on the side close to the pilot valve plunger (1). A retaining ring (11) abuts against the side of the main seal (3) away from the plunger guide sleeve (14). The retaining ring (11) is a flange structure with a flange. The flange face is positioned on the sealing hole shoulder seat provided inside the pilot valve body (5). 11) The inner hole supports the main sealing element (3). The pilot valve body (5) has a plunger hole and a sealing hole inside. The pilot valve body (5) has a valve core (7) installed inside. The valve core (7) is fitted with a metering spring (8) and a return spring (6) on its outer periphery. The metering spring (8) and the return spring (6) are abutted by a retaining pad (9) at one end near the pilot valve plunger (1). An open retaining ring (10) is installed on the outer periphery of the pilot valve plunger (1) near the valve core (7). The plunger guide sleeve (14) is provided with a first O-ring (2) on the side close to the pilot valve plunger (1), and a second O-ring (4) is provided on the end of the plunger guide sleeve (14) away from the pilot valve plunger (1). The main sealing element (3) includes a fixed sleeve (15), which is disposed inside the plunger guide sleeve (14). The plunger guide sleeve (14) presses against the upper surface of the flange of the retaining ring (11). The fixed sleeve (15) of the main sealing element (3) presses against the upper end face of the retaining ring (11). The fixed sleeve (15) is provided with hydrogenated nitrile rubber (16) on the side of the fixed sleeve (15) close to the pilot valve plunger (1). The hydrogenated nitrile rubber (16) is provided with a sealing upper lip (19) and a sealing lower lip (18) on the side of the hydrogenated nitrile rubber (16) close to the pilot valve plunger (1). The side of the hydrogenated nitrile rubber (16) away from the pilot valve plunger (1) is provided with a self-tightening spring (17). The plunger guide sleeve (14) has a static sealing groove (22) in the middle, and the upper part of the main sealing element (3) extends into the static sealing groove (22). The upper sealing lip (19) is press-fitted with the inner side of the static sealing groove (22) to perform static sealing. The valve core (7) is slidably connected inside the pilot valve plunger (1), and the main seal (3) is interference-fitted with the pilot valve plunger (1).

2. The pilot valve plunger sealing structure according to claim 1, characterized in that, The plunger guide sleeve (14) has an inner sealing groove (20) inside, which is used to install the first O-ring (2). The plunger guide sleeve (14) has an outer sealing groove (21) on its outer periphery, which is used to install the second O-ring (4).

3. The pilot valve plunger sealing structure according to claim 1, characterized in that, The plunger guide sleeve (14) is provided with an mounting plate (12) on the outer periphery away from the pilot valve plunger (1), and the mounting plate (12) is fixed to the outer periphery of the pilot valve body (5) by fastening screws (13).

4. The pilot valve plunger sealing structure according to claim 1, characterized in that, The valve core (7) is slidably connected to the middle of the retaining pad (9), and the side of the retaining pad (9) away from the metering spring (8) abuts against the end of the pilot valve plunger (1) near the valve core (7).

Images