A piston assembly for an oil hydraulic shock absorber

Abstract

The utility model relates to the field of oil pressure damping, specifically relates to a kind of oil pressure damper piston assembly. Including piston, valve piece, piston rod and piston nut;Piston is sleeved and fixed on piston rod, and piston assembly is divided into stretch cavity and compression cavity;Piston is provided with stretch hole and compression hole through its ontology;Valve piece includes the first valve piece and second valve piece corresponding to cover on stretch hole and compression hole;The surface of piston and the first valve piece and second valve piece contact respectively is first sealing surface and second sealing surface, and first sealing surface and second sealing surface are all the composite surface formed by at least two different curvature curve segments;Piston nut provides pre-tightening force, so that the first valve piece and second valve piece produce bending deformation and are closely attached with first sealing surface and second sealing surface respectively.The present application fundamentally solves the internal oil leakage problem caused by the sealing of existing structure not being tight.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic vibration damping, specifically to a piston assembly for a hydraulic vibration damper. Background Technology

[0002] Hydraulic vibration dampers are core shock-absorbing components in rail transit, construction machinery, and other fields. Their damping characteristics directly determine the operational stability and ride comfort of the equipment. Especially in the field of high-speed trains, the performance of the damper is a key factor affecting driving safety. In existing technologies, hydraulic vibration dampers mostly adopt a dual-circulation structure. When the damper is in the compression stroke, the oil pressure in the lower chamber of the piston increases, and the oil flows into the upper chamber through the piston throttle orifice. Excess oil pushes open the compression valve and flows back to the reservoir. In the extension stroke, the oil pressure in the upper chamber of the piston increases, and the oil flows into the lower chamber through the throttle orifice. The oil in the reservoir is then replenished to the lower chamber through the compensation valve. The resistance of the valve system to the oil creates a corresponding damping force. However, existing valve systems generally face the technical bottleneck of poor sealing performance, which easily leads to internal oil leakage, causing the damping characteristics to deviate from the design specifications and affecting the working stability of the vibration damper.

[0003] The retrieved prior art document CN113819180A discloses a multi-curved surface sealing structure for a hydraulic shock absorber valve system. This structure achieves sealing by setting grooves on the upper and lower surfaces of the piston and using a limiter to cooperate with the valve plate assembly. Its sealing surface is composed of three smoothly connected curved surfaces with different curvatures. Although this patent attempts to improve the sealing effect through a multi-curved surface design, in practical applications, its complex design and lack of precise optimization for the fit characteristics between the valve plate and the sealing surface mean that when the shock absorber is operating at low speeds, the valve plate and the sealing surface are still prone to loose fit, making it difficult to effectively control internal leakage. Especially for shock absorbers used in high-speed trains, this leakage problem directly affects the stability of low-speed damping force, failing to meet the design requirements for high-precision damping characteristics. Therefore, a more rationally designed piston assembly with a more reliable seal is urgently needed to solve this core problem. Summary of the Invention

[0004] The purpose of this invention is to provide a piston assembly for a hydraulic damper to solve the problem of internal oil leakage caused by poor sealing in existing structures.

[0005] To achieve the above objectives, the following technical solution is adopted.

[0006] A hydraulic shock absorber piston assembly includes a piston, a valve plate, a piston rod, and a piston nut; the piston is fitted and fixed on the piston rod, dividing the piston assembly into a tension chamber and a compression chamber; the piston has a tension hole and a compression hole penetrating its body; The valve plate includes a first valve plate and a second valve plate correspondingly covering the stretching hole and the compression hole; the surfaces on the piston that contact the first valve plate and the second valve plate are respectively a first sealing surface and a second sealing surface, and both the first sealing surface and the second sealing surface are composite curved surfaces composed of at least two curve segments with different curvatures; the piston nut provides a preload force, causing the first valve plate and the second valve plate to bend and deform and fit tightly against the first sealing surface and the second sealing surface, respectively.

[0007] Optionally, the first sealing surface is formed by a smooth connection of a first curvature curve segment and a second curvature curve segment.

[0008] Optionally, the second sealing surface is formed by a smooth connection of a third curvature curve segment and a fourth curvature curve segment.

[0009] Optionally, it also includes a gasket, a limiting seat, and a piston limiting valve; there are two piston limiting valves respectively disposed at the upper and lower ends of the piston; there are two limiting seats respectively disposed on the piston rod, located above and below the piston; the gasket includes a first gasket, a second gasket, and a third gasket; the first gasket is located between the limiting seat above the piston and the piston rod, the second gasket is located between the limiting seat above the piston and the piston limiting valve, and the third gasket is located between the limiting seat below the piston and the piston limiting valve.

[0010] Optionally, the stretching holes and compression holes are arranged in a spaced annular array along the center of the piston.

[0011] Optionally, the stretching hole is connected to a corresponding stretching oil passage on the piston. The oil inlet of the stretching oil passage is vertically arranged, and the oil outlet of the stretching oil passage is horizontally arranged above its oil inlet. The oil outlet port of the stretching oil passage is an angled port. The compression hole is connected to a corresponding compression oil passage on the piston. The oil inlet of the compression oil passage is vertically arranged, and the oil outlet of the compression oil passage is horizontally arranged below its oil inlet. The oil outlet port of the compression oil passage is an angled port.

[0012] Optionally, curve segments with different curvatures can be arranged along the radial direction of the piston.

[0013] Optionally, the piston is also provided with a throttling orifice for constant oil flow.

[0014] Optionally, the first valve plate bends and deforms under the preload and fits against the first sealing surface to seal the oil passage where the stretching hole is located at the beginning of the stretching stroke.

[0015] Optionally, the second valve plate bends and deforms under the preload and fits against the second sealing surface to seal the oil passage where the compression hole is located at the beginning of the compression stroke.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This application fundamentally solves the problem of internal oil leakage caused by poor sealing in existing structures by designing the first and second sealing surfaces of the piston and valve plate as composite surfaces composed of at least two segments with different curvatures. The piston nut provides preload, causing the valve plate to bend and deform, thus ensuring a tight seal. The composite surface design adapts to the bending deformation trajectory of the valve plate under preload, resulting in surface contact rather than line contact between the valve plate and the sealing surface. This significantly increases the sealing contact area. Combined with the stable preload provided by the piston nut, it effectively blocks the leakage path of oil at the sealing surface, ensuring that the damper maintains stable damping force even at low speeds, achieving precise control of damping characteristics. Furthermore, this structure eliminates the need for complex limiting components, simplifying the overall assembly process and reducing manufacturing costs while maintaining sealing performance. It is particularly suitable for high-speed train dampers where high reliability is required.

[0017] By clearly defining that the first sealing surface and k are each smoothly connected by two specific curvature curve segments, the design of the composite surface becomes more targeted. The curvature parameters can be optimized according to the oil pressure characteristics under different strokes, further improving the fitting accuracy between the sealing surface and the valve plate. The added gasket, limit seat, and piston limit valve, through multi-component coordinated positioning, effectively limit the radial displacement of the piston and valve plate, avoiding misalignment of the sealing surface caused by vibration, providing double protection for sealing performance. The spaced annular array arrangement of the tension holes and compression holes makes the oil flow more uniform, reducing the impact of local pressure concentration on the sealing surface. The design optimizes the direction and port shape of the oil inlet and outlet, reducing oil flow resistance. The angled port design also reduces oil erosion and wear on the valve plates, extending the service life of the sealing structure. Different curvature curve segments are arranged radially, resulting in more uniform force distribution on the valve plates and more regular bending, further improving sealing stability. The normally open throttling orifice ensures oil flow under extreme conditions, preventing pressure surges from damaging the sealing structure. The sealing function of the valve plates at the initial stage of the stroke is clearly defined, making damping force adjustment more controllable and providing strong support for optimizing the overall performance of the shock absorber. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the reciprocating motion of a piston assembly in a hydraulic shock absorber according to the present invention. Figure 2 This is a schematic diagram of the piston assembly of a hydraulic shock absorber piston assembly according to the present invention; Figure 3 This is a top view of the piston assembly of a hydraulic shock absorber according to the present invention; Figure 4 This is a bottom view of the piston assembly of a hydraulic shock absorber according to this utility model; Figure 5 This is a schematic diagram of the piston and valve plate contact in a piston assembly of a hydraulic damper according to this utility model; Figure 6 This is a schematic diagram of the piston sealing surface structure of a hydraulic shock absorber piston assembly according to the present invention; Wherein: 1. Tensioning hole; 2. Compression hole; 3. Piston; 4. First valve plate; 5. Second valve plate; 6. Piston rod; 7. Piston nut; 8. Tensioning chamber; 9. Compression chamber; 10. First sealing surface; 11. Second sealing surface; 12. First curvature curve segment; 13. Second curvature curve segment; 14. Third curvature curve segment; 15. Fourth curvature curve segment; 16. Limiting seat; 17. Piston limiting valve; 18. First gasket; 19. Second gasket; 20. Third gasket; 21. Throttling orifice. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0020] The following detailed description is exemplary and intended to provide further detailed explanation of the present invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to the present invention.

[0021] like Figures 1-6 As shown, the hydraulic shock absorber piston assembly disclosed in this embodiment is mainly used to mitigate vibration transmission between the vehicle body and the bogie, ensuring the vehicle's stability and comfort at different operating speeds. Through precise structural design, this piston assembly solves the problems of poor sealing and internal oil leakage in traditional shock absorber piston three-valve systems, enabling stable achievement of the designed damping characteristics, especially exhibiting excellent damping force control precision under low-speed operating conditions. The following provides a detailed description of its technical solution, combining the overall structure of the assembly, the specific design of each component, and its working process.

[0022] The core load-bearing component of the assembly is the piston rod 6, which is made of high-strength alloy steel. After tempering, the surface is chrome-plated, with the chrome plating thickness controlled between 0.05 and 0.1 mm and the surface roughness not exceeding Ra 0.2 μm. This material selection and processing technology ensures that the piston rod 6 has sufficient strength to withstand the axial load during reciprocating motion, while the smooth chrome-plated surface reduces friction and wear with surrounding components and improves corrosion resistance, allowing it to withstand the long-term effects of the internal oil of the shock absorber and the external environment. One end of the piston rod 6 is equipped with an external thread structure for pre-tightening and fixing the assembly with the piston nut 7. The thread precision is 6g grade to ensure the reliability and stability of the connection. The other end is connected to the shock absorber's linkage mechanism through a spline structure. The number of teeth and module of the spline are matched according to the load requirements of the train shock absorber to ensure smooth power transmission.

[0023] Piston 3 is made of alloy cast iron, which has good wear resistance and dimensional stability, and can maintain structural accuracy under long-term oil impact and friction conditions. An axially through mounting hole is provided in the center of piston 3. The inner diameter of the mounting hole and the outer diameter of piston rod 6 are designed with an interference fit, with the interference controlled within the range of 0.01 to 0.03 mm. Piston 3 is fixed in the preset position on piston rod 6 by a press-fit process. After assembly, the upper and lower end faces of piston 3 are perpendicular to the axis of piston rod 6, with a perpendicularity error not exceeding 0.02 mm, to ensure that piston 3 can move smoothly along the axis of piston rod 6 during reciprocating motion, avoiding local wear and sealing failure caused by eccentricity. Piston 3 clearly divides the working chamber of the shock absorber into a tension chamber 8 above and a compression chamber 9 below. The volume of the two chambers changes periodically with the movement of piston 3, thereby driving the oil flow and generating damping force.

[0024] On the piston 3 body, multiple sets of through-holes 1 and 2 are formed along the circumference. These channels are the main passages for oil flow between the tension chamber 8 and the compression chamber 9. The number of tension holes 1 and compression holes 2 is set according to the flow requirements of the damper. Typically, each set of channels contains 4 to 8 holes, arranged in a spaced-out ring array along the central axis of the piston 3. The central angle between two adjacent holes is equal, ensuring that the oil can act evenly on the valve plate surface during flow and avoiding premature valve plate damage caused by local pressure concentration. The diameter of the tension holes 1 and compression holes 2 is determined according to the designed damping coefficient. The inner wall of the channel is honed, with a surface roughness of no more than Ra0.4μm, reducing friction resistance during oil flow and avoiding oil turbulence and energy loss caused by rough hole walls.

[0025] The valve plates used to control the opening and closing of the tension hole 1 and compression hole 2 are made of spring steel, commonly grade 60Si2MnA. This material, after quenching and medium-temperature tempering, possesses excellent elastic limit and fatigue strength, maintaining stable mechanical properties during frequent bending deformation and is not prone to permanent deformation or fracture. The valve plates include a first valve plate 4 and a second valve plate 5, respectively covering the outer ports of the tension hole 1 and compression hole 2. Both the first valve plate 4 and the second valve plate 5 are circular in shape, with a diameter slightly larger than the diameter of the corresponding hole distribution circle, ensuring complete coverage of all hole ports for reliable sealing. The thickness of the valve plates is designed according to the preload and oil pressure requirements, typically between 0.1 and 0.3 mm. The thinner thickness ensures that the valve plates deform under a small pressure difference, opening the holes, while appropriate elasticity ensures that the valve plates quickly return to their original position after the pressure is released, restoring a seal.

[0026] The surfaces of piston 3 that contact the first valve plate 4 and the second valve plate 5 respectively constitute the sealing surface and the sealing surface. These two sealing surfaces are the core structures that ensure the sealing performance of the component, and their design quality directly determines whether the shock absorber will experience internal oil leakage. Both the sealing surface and the sealing surface adopt a composite curved surface structure, which is smoothly connected by at least two curve segments with different curvatures. This structural design can perfectly match the bending deformation trajectory of the valve plate under the action of preload, so that the valve plate and the sealing surface form a full-area tight fit, rather than the line contact or partial surface contact in traditional planar seals, thereby greatly improving the sealing reliability. Taking the sealing surface as an example, it is composed of a first curvature curve segment 12 and a second curvature curve segment 13. The first curvature curve segment 12 is located in the inner region near the center of piston 3, and the second curvature curve segment 13 is located in the outer region away from the center. The connection between the two curve segments adopts an arc transition with a transition radius of not less than 0.5 mm, ensuring that the valve plate can smoothly transition during the fitting process and avoiding stress concentration at the connection. The surface roughness of the sealing surface is controlled below Ra0.1μm and is processed using ultra-precision grinding technology to reduce the friction coefficient between the valve plate and the sealing surface, while avoiding sealing gaps caused by surface defects.

[0027] To ensure stable contact between the first valve plate 4 and the second valve plate 5 on their respective sealing surfaces, the piston assembly provides a continuous and stable preload through the piston nut 7. The piston nut 7 employs an internal thread structure that matches the external thread of the piston rod 6. It is made of high-strength carbon steel and undergoes carburizing and quenching treatment to improve the wear resistance and shear strength of the threaded portion. During assembly, after fitting the piston nut 7 onto the threaded end of the piston rod 6, it is tightened using a torque wrench according to a preset torque value. The preload is precisely controlled by adjusting the tightening torque. The preload value is determined based on the elastic characteristics of the valve plates and sealing requirements, typically controlled between 50 and 100 Newtons. This ensures that the valve plates can undergo appropriate bending deformation, guaranteeing a tight fit with the sealing surface without causing permanent deformation or excessive fatigue due to excessive preload. To prevent the piston nut 7 from loosening due to vibration during the operation of the shock absorber, a locking washer is also provided between the piston nut 7 and the adjacent components. The inner hole of the locking washer adopts a non-circular structure to cooperate with the piston rod 6, and the outer ring is fitted with the end face of the piston nut 7 through a flanged structure, forming a reliable anti-loosening effect.

[0028] To further enhance the structural stability and operational reliability of the assembly, the piston assembly also includes a gasket, a limiting seat 16, and a piston limiting valve 17. These components work together to achieve precise control of the valve plate's movement, preventing damage due to excessive deformation and optimizing the oil flow path. The limiting seat 16 is made of 45# steel and, after heat treatment, possesses good strength and toughness. Two seats are used, one mounted on the piston rod 6 and the other at the upper and lower ends of the piston 3. The center of the limiting seat 16 has a channel that mates with the piston rod 6, employing a clearance fit design with the clearance controlled between 0.02 and 0.05 mm. This ensures smooth movement of the limiting seat 16 along the piston rod 6 while preventing radial wobble caused by excessive clearance. Each limiting seat 16 has an annular boss at one end, the end face of which corresponds to the edge area of ​​the valve plate. This limits the maximum deformation of the valve plate under oil pressure, preventing breakage due to deformation exceeding the elastic limit.

[0029] Two piston limit valves 17 are also provided, installed at the upper and lower ends of the piston 3 respectively, located between the limit seat 16 and the piston 3. The piston limit valve 17 adopts a thin plate structure, made of the same material as the valve plate, and has multiple evenly distributed flow holes on its surface to facilitate the flow of oil under specific operating conditions. When the shock absorber is under extreme operating conditions, and the oil pressure rises sharply, causing the valve plate to deform significantly, the valve plate will come into contact with the piston limit valve 17. At this time, the piston limit valve 17 can both limit the further deformation of the valve plate and provide additional flow channels for the oil through its surface flow holes, preventing excessive oil pressure from damaging the components.

[0030] The gaskets include a first gasket 18, a second gasket 19, and a third gasket 20, all made of copper alloy. Copper alloy has good ductility and wear resistance, enabling reliable contact between components while reducing wear caused by mutual friction. The first gasket 18 is located between the limiting seat 16 above the piston 3 and the piston rod 6. Its main function is to fill the mating gap between the limiting seat 16 and the piston rod 6, preventing the limiting seat 16 from wobbling in the radial direction and ensuring that the limiting seat 16 accurately and reliably limits the valve plate. The second gasket 19 is located between the limiting seat 16 above the piston 3 and the piston limiting valve 17, and the third gasket 20 is located between the limiting seat 16 below the piston 3 and the piston limiting valve 17. The thickness of these two gaskets is controlled between 0.1 and 0.3 mm, which can effectively buffer the vibration and impact between the limiting seat 16 and the piston limiting valve 17. At the same time, by adjusting the thickness of the gaskets, the initial preload of the valve plate can be fine-tuned to ensure that the force on multiple valve plates is uniform.

[0031] The tensioning orifice 1 connects to a corresponding tensioning oil passage inside the piston 3, while the compression orifice 2 connects to a corresponding compression oil passage. The structural design of these oil passages directly affects the flow characteristics of the oil and the stability of the damping force. The inlet of the tensioning oil passage is vertically oriented, with its inlet connected to the inner port of the tensioning orifice 1. The diameter of the inlet is consistent with that of the tensioning orifice 1, ensuring smooth oil flow into the oil passage. The outlet of the tensioning oil passage is located above the inlet, oriented laterally, with its outlet facing the tensioning cavity 8. This bent oil passage structure extends the flow path of the oil, increases the friction resistance, and thus improves the accuracy of damping adjustment. The outlet port is angled at 45 degrees. This design allows the oil to flow tangentially into the tensioning cavity 8 after exiting the oil passage, reducing the impact between the oil and the cavity wall, avoiding turbulent noise, and allowing the oil to be more evenly distributed within the tensioning cavity 8.

[0032] The structure of the compression oil circuit is similar to that of the tension oil circuit. Its inlet is also vertically positioned and connected to the inner port of compression orifice 2. The outlet is located below the inlet and is horizontally positioned, with the outlet facing the compression chamber 9. The outlet port of the compression oil circuit is also a 45-degree angled port, serving the same purpose as the outlet port of the tension oil circuit: optimizing the oil flow direction and reducing impact and turbulence. The inner walls of both the tension and compression oil circuits are precision-machined, with a surface roughness not exceeding Ra0.4μm. The bends in the oil circuits use rounded transitions with a transition radius not less than 1.5 times the diameter of the oil circuit orifice, ensuring no significant pressure loss during oil flow and guaranteeing the stability of the damping force.

[0033] Different curvature curve segments are arranged radially along the piston 3 on both the sealing surface and the sealing surface. This arrangement matches the stress deformation characteristics of the valve plate. When the valve plate bends under preload, its deformation tends to gradually increase radially from the center outwards. Arranging the curve segments of the sealing surface radially ensures that the curvature change of the sealing surface is consistent with the deformation curve of the valve plate, thereby achieving full fit between the valve plate and the sealing surface. Taking the sealing surface as an example, the first curvature curve segment 12 has a smaller radius of curvature, corresponding to the smaller deformation near the center of the valve plate, while the second curvature curve segment 13 has a larger radius of curvature, corresponding to the larger deformation on the outer side of the valve plate. The smooth connection of the two curve segments ensures that the fitting pressure of the valve plate is evenly distributed across the entire contact surface, avoiding localized overly tight or loose fits, and further improving the sealing performance.

[0034] The piston 3 is also provided with throttling orifices 21 for the constant flow of oil. These throttling orifices 21 are independent of the tension orifice 1 and the compression orifice 2, and there are usually 2 to 4 of them, evenly distributed along the circumference of the piston 3. The diameter of the throttling orifice 21 is much smaller than that of the tension orifice 1 and the compression orifice 2, usually between 0.5 and 1 mm. Its function is to provide the necessary flow channel for oil when the shock absorber is operating at low speed. When the train speed is low, the piston 3 moves slowly, and the pressure difference between the tension chamber 8 and the compression chamber 9 is small. At this time, the first valve plate 4 and the second valve plate 5 are kept in contact with the sealing surface under the action of preload. The tension orifice 1 and the compression orifice 2 are in the closed state. The oil mainly flows between the two chambers through the constantly open throttling orifice 21, thereby generating a stable low-speed damping force and avoiding sudden changes in damping force caused by the inability of oil to flow, thus improving the ride comfort of the train. The inner wall of the throttling orifice 21 is also finely ground to ensure the stability and consistency of the oil flow.

[0035] The following section details the working process of the piston assembly and the synergistic mechanism of its components, focusing on the extension and compression strokes of the shock absorber. When vibration occurs during train operation, causing the shock absorber to enter its extension stroke, the car body moves upward relative to the bogie, driving the piston rod 6 upward, which in turn pulls the piston 3 upward synchronously. At this time, the volume of the extension chamber 8 increases, and the internal oil pressure decreases, while the volume of the compression chamber 9 decreases, and the internal oil pressure increases, creating a pressure difference. In the initial stage of the stroke, the pressure difference is small and insufficient to overcome the preload applied by the piston nut 7. Under the action of the preload, the first valve plate 4 remains in a bent deformation state, tightly fitting against the sealing surface, thereby sealing the oil passage where the extension hole 1 is located. At this time, the oil mainly flows from the compression chamber 9 to the extension chamber 8 through the normally open throttling orifice 21 on the piston 3. The resistance of the throttling orifice 21 to the oil forms an initial low-speed damping force, which can effectively mitigate small vibrations and improve the riding experience.

[0036] As the vibration amplitude increases, the piston 3 moves faster, and the pressure difference between the compression chamber 9 and the tension chamber 8 also increases. When the pressure difference reaches a preset threshold, the force generated can overcome the preload, pushing the first valve plate 4 to deform upwards to a greater extent, creating a gap between the first valve plate 4 and the sealing surface, and opening the oil passage where the tension hole 1 is located. At this time, in addition to flowing through the throttling hole 21, most of the oil will enter the compression oil circuit through the compression hole 2, and flow into the compression chamber 9 through the oil outlet of the compression oil circuit. At the same time, some oil will enter the tension oil circuit through the tension hole 1, and then flow into the tension chamber 8. When the oil passes through these channels and oil circuits, it will be subject to the frictional resistance of the hole wall and the throttling effect of the valve plate, thereby generating a large damping force, effectively suppressing large-amplitude vibrations. During this process, the limiting seat 16 located above the piston 3 will limit the maximum deformation of the first valve plate 4 to prevent the first valve plate 4 from being damaged due to excessive deformation. The second gasket 19 plays a buffering role between the limiting seat 16 and the piston limiting valve 17 to ensure that the limiting process is smooth and reliable.

[0037] When the shock absorber enters the compression stroke, the car body moves downward relative to the bogie. Piston rod 6 pushes piston 3 downward, at which point the volume of compression chamber 9 decreases and the oil pressure increases, while the volume of tension chamber 8 increases and the oil pressure decreases. Similar to the tension stroke, in the initial stage of the stroke, the pressure difference is small, and the second valve plate 5 remains tightly fitted to the sealing surface under the preload, closing the oil passage where compression hole 2 is located. The oil still flows from tension chamber 8 to compression chamber 9 through the normally open throttling orifice 21, generating a stable low-speed damping force. As the stroke progresses, the piston 3 moves faster, and the pressure difference increases. When the pressure difference exceeds the preload, the second valve plate 5 deforms downward, forming a gap with the sealing surface. The oil passage where compression hole 2 is located opens, and a large amount of oil flows between the two chambers through tension hole 1, tension oil passage, and compression hole 2, compression oil passage, generating a large damping force to suppress vibration. At this time, the limiting seat 16 and the third gasket 20 located below piston 3 work together to limit the maximum deformation of the second valve plate 5, ensuring that it operates within a safe range.

[0038] Throughout the entire operation, the sealing surface and its composite curved surface structure play a crucial role. Because the curvature change of the composite surface matches the deformation curve of the valve plate, good contact characteristics are maintained between the valve plate and the sealing surface regardless of whether the valve plate is in its initial contact state or in its deformed open state. In the initial contact state, full-area contact ensures reliable sealing and prevents oil leakage; in the deformed open state, the contact area between the valve plate and the sealing surface gradually decreases, but still maintains localized tight contact, preventing excessive leakage gaps. This design effectively solves the problem of increased sealing gaps and oil leakage after valve plate deformation in traditional planar seals, ensuring that the damper maintains stable damping characteristics throughout its entire service life.

[0039] Furthermore, the selection of materials and processing techniques for each component provides a strong guarantee for the reliable operation of the assembly. The high-strength material and chrome-plated surface treatment of piston rod 6 ensure its load-bearing capacity and wear resistance; the alloy cast iron material and precision machining of piston 3 guarantee its dimensional stability and sealing surface accuracy; the spring steel material and heat treatment process of valve plate give it excellent elasticity and fatigue strength; the rational design of auxiliary components such as limit seat 16 and gaskets further optimizes the stress state and working stability of the assembly. The organic combination of these design details makes the entire piston assembly a collaborative whole, which not only solves the sealing defects of traditional structures, but also achieves precise control of damping characteristics, fully meeting the needs of high-speed trains and other applications with extremely high requirements for vibration damper performance.

[0040] In practical applications, this piston assembly has demonstrated excellent performance through multiple bench tests and track tests. In bench tests, the assembly was installed on a standard vibration damper test bench and subjected to 1 million cycles of reciprocating fatigue testing. Post-test disassembly and inspection revealed no significant wear on any components, good contact between the valve plate and the sealing surface, and no oil leakage. Damping force test results showed that within a piston speed range of 0.01 to 1.0 m / s, the damping force fluctuation did not exceed ±5%, far superior to the ±10% fluctuation range of traditional structures. In track tests, high-speed trains equipped with this piston assembly operated under different track conditions, exhibiting significantly reduced vehicle vibration acceleration and a passenger comfort score more than 20% higher than trains using traditional assemblies, fully demonstrating the practicality and superiority of this piston assembly.

[0041] In summary, the hydraulic vibration damper piston assembly disclosed in this embodiment effectively solves the problems of poor sealing and easy leakage in traditional vibration damper piston assemblies through precise design of key structures such as sealing surfaces, valve plates, and oil passages, combined with reasonable material selection and processing technology, thus achieving stable control of damping characteristics. Its overall structural design is reasonable, its operation is reliable, and its service life is long. It can be widely used in various equipment requiring high-precision vibration damping, such as high-speed trains, urban rail transit vehicles, and construction machinery, and has significant practical application value and promising prospects for promotion.

[0042] As is known from common technical knowledge, this utility model can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the above-disclosed embodiments are merely illustrative in all respects and are not the only ones. All modifications within the scope of this utility model or its equivalents are included in this utility model.

Claims

1. A piston assembly for a hydraulic damper, characterized in that, It includes a piston (3), a valve plate, a piston rod (6) and a piston nut (7); the piston (3) is fitted and fixed on the piston rod (6) and the piston assembly is divided into a tension chamber (8) and a compression chamber (9); the piston (3) is provided with a tension hole (1) and a compression hole (2) that penetrate its body; The valve plate includes a first valve plate (4) and a second valve plate (5) corresponding to the tension hole (1) and the compression hole (2); the surfaces of the piston (3) that contact the first valve plate (4) and the second valve plate (5) are a first sealing surface (10) and a second sealing surface (11), respectively, and the first sealing surface (10) and the second sealing surface (11) are both composite curved surfaces composed of at least two curve segments with different curvatures; the piston nut (7) provides a preload force, causing the first valve plate (4) and the second valve plate (5) to bend and deform and fit tightly against the first sealing surface (10) and the second sealing surface (11), respectively.

2. The hydraulic damper piston assembly according to claim 1, characterized in that: The first sealing surface (10) is formed by a smooth connection of a first curvature curve segment (12) and a second curvature curve segment (13).

3. The hydraulic damper piston assembly according to claim 1, characterized in that: The second sealing surface (11) is formed by the smooth connection of the third curvature curve segment (14) and the fourth curvature curve segment (15).

4. The hydraulic damper piston assembly according to claim 1, characterized in that: It also includes a gasket, a limiting seat (16), and a piston limiting valve (17); there are two piston limiting valves (17) respectively disposed at the upper and lower ends of the piston (3); there are two limiting seats (16) respectively disposed on the piston rod (6), located above and below the piston (3); the gasket includes a first gasket (18), a second gasket (19), and a third gasket (20); the first gasket (18) is located between the limiting seat (16) above the piston (3) and the piston rod (6), the second gasket (19) is located between the limiting seat (16) above the piston (3) and the piston limiting valve (17), and the third gasket (20) is located between the limiting seat (16) below the piston (3) and the piston limiting valve (17).

5. The hydraulic damper piston assembly according to claim 4, characterized in that: The stretching holes (1) and compression holes (2) are arranged in a spaced ring array along the center of the piston (3) on the piston (3).

6. The hydraulic damper piston assembly according to claim 1, characterized in that: The stretching hole (1) is connected to the piston (3) with a corresponding stretching oil passage. The oil inlet of the stretching oil passage is vertically arranged, and the oil outlet of the stretching oil passage is horizontally arranged above its oil inlet. The oil outlet port of the stretching oil passage is an angled port. The compression hole (2) is connected to the piston (3) with a corresponding compression oil passage. The oil inlet of the compression oil passage is vertically arranged, and the oil outlet of the compression oil passage is horizontally arranged below its oil inlet. The oil outlet port of the compression oil passage is an angled port.

7. The hydraulic damper piston assembly according to claim 2 or 3, characterized in that: Curved segments with different curvatures are arranged along the radial direction of the piston (3).

8. The hydraulic damper piston assembly according to claim 1, characterized in that: The piston (3) is also provided with a throttling orifice (21) for the constant flow of oil.

9. The hydraulic damper piston assembly according to claim 1, characterized in that: The first valve plate (4) bends and deforms under the action of preload and fits against the first sealing surface (10) to seal the oil passage where the tension hole (1) is located in the early stage of the tension stroke.

10. The hydraulic damper piston assembly according to claim 1, characterized in that: The second valve plate (5) bends and deforms under the action of preload and fits into the second sealing surface (11) to seal the oil passage where the compression hole (2) is located at the beginning of the compression stroke.

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