Piston assembly of magneto-rheological damper and magneto-rheological damper

Abstract

This invention discloses a piston assembly and a magnetorheological vibration damper, relating to the field of vibration damper technology. The piston assembly includes a piston rod and a piston sleeve disposed within an oil reservoir. The piston sleeve includes a piston base and an encapsulation layer. The piston base contains an upper piston cover, a lower piston cover, and a coil assembly. The encapsulation layer is disposed between the piston base and the oil reservoir. An annular groove is formed on the outer side of the piston base, and a protrusion adapted to the groove is formed on the inner side of the encapsulation layer. The two are interlocked. The outer side of the encapsulation layer abuts against the inner wall of the oil reservoir and moves up and down along the length of the oil reservoir with the piston assembly. This invention, through the interlocking structure of the annular groove and the protrusion, the shape design of the annular groove, the differentiated size design, and the encapsulation layer made of highly wear-resistant material, comprehensively solves the problems of poor bonding force, large magnetic field interference, and easy wear of traditional piston surface protection structures, significantly improving the overall service life and operational stability of the magnetorheological vibration damper.

Description

Technical Field

[0001] This invention relates to the field of vibration damper technology, and in particular to a piston assembly and a magnetorheological vibration damper. Background Technology

[0002] Magnetorheological dampers are a novel type of vibration damping device based on magnetorheological fluid technology. Magnetorheological fluids typically consist of micron-sized magnetic particles suspended in a carrier liquid. In the absence of an external magnetic field, the magnetorheological fluid behaves as a low-viscosity Newtonian fluid; when a magnetic field is applied, the suspended magnetic particles are instantly magnetized and align along the magnetic field lines into chain-like or columnar structures, causing a sharp increase in the apparent viscosity of the liquid, even exhibiting solid-like properties, thus generating high shear yield stress. By adjusting the magnetic field strength, the damping force can be continuously, reversibly, and rapidly controlled. Based on these principles, magnetorheological dampers have significant advantages such as fast response speed, low energy consumption, and compact structure, and have been widely used in vehicle suspension systems to mitigate road impacts, quickly absorb vibrations generated during bumps, and restore the vehicle to normal driving conditions.

[0003] In practical applications, the piston of a magnetorheological damper, as the core moving component, needs to undergo high-frequency reciprocating motion and high-pressure friction conditions for extended periods within a cylinder filled with magnetorheological fluid. However, due to the high hardness of the magnetic particles suspended in the magnetorheological fluid, such as carbonyl iron powder, these hard magnetic particles generate continuous micro-cutting and abrasive wear at the gap between the piston and the cylinder as the piston reciprocates within the cylinder. Under prolonged high-frequency, high-pressure cycling, the piston surface is prone to developing noticeable scratches, grooves, and material spalling, leading to increased roughness of the piston's working surface. This not only exacerbates internal friction within the damper but also disrupts the sealing fit between the piston and the cylinder, resulting in unstable damping performance, reduced damping force, and even overall functional failure. Therefore, improving the surface wear resistance of the piston under harsh conditions containing hard magnetic particles is a key technical challenge for extending the service life of magnetorheological dampers. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a piston assembly and a magnetorheological damper for a magnetorheological damper, which are mainly used in magnetorheological fluid dampers to improve the wear resistance of the piston surface and extend the service life of the piston assembly and the magnetorheological damper.

[0005] This invention discloses a piston assembly for a magnetorheological vibration damper, comprising a piston rod and a piston sleeve movably disposed within an oil reservoir. The piston sleeve includes a piston base and an encapsulation layer. The piston base is hollow, with a piston top cover at the top and a piston bottom cover at the bottom. A piston coil assembly located inside the piston base is disposed between the piston top cover and the piston bottom cover. A channel for liquid flow is provided between the outer wall of the piston coil assembly and the inner wall of the piston base. Both the piston top cover and the piston bottom cover have a first through hole communicating with the channel. The end of the piston rod passes through the piston top cover and the piston coil assembly in sequence and is sealed to the piston bottom cover. The piston rod is sealed to the piston top cover and the piston coil assembly.

[0006] The encapsulation layer is disposed between the piston base and the oil reservoir and is located in the middle of the piston base. An annular groove is provided on the outer side of the piston base along the length direction of the piston base. A protrusion adapted to the annular groove is provided on the inner side of the encapsulation layer. The protrusion engages with the annular groove. The outer side of the encapsulation layer abuts against the inner wall of the oil reservoir and moves up and down with the piston base along the length direction of the oil reservoir.

[0007] Furthermore, the annular groove includes a bottom groove, a middle groove, and a top groove arranged sequentially from bottom to top. The bottom groove is located at one end of the piston base near the lower piston cover, and the depth of the bottom groove is greater than the depth of the middle groove and the top groove. The top groove is located at one end of the piston base near the upper piston cover, and the width of the top groove is greater than the width of the middle groove and the bottom groove. The protrusion includes a bottom protrusion, a middle protrusion, and a top protrusion corresponding to the bottom groove, the middle groove, and the top groove, respectively.

[0008] As a preferred embodiment, the bottom groove, the middle groove, and the top groove all have dovetail or trapezoidal cross sections, and their groove opening width is smaller than the groove bottom width, forming an inverted structure that interlocks with the encapsulation layer.

[0009] As a preferred embodiment, the cross-section of the bottom groove has a dovetail-shaped structure with a rounded transition.

[0010] As a preferred embodiment, at least two grooves are evenly distributed in the central part.

[0011] Furthermore, the encapsulation layer is made of polyetheretherketone filled with carbon fiber or graphite; the surface of the annular groove is sandblasted.

[0012] Furthermore, the top of the piston base is provided with an upper slot adapted to the piston upper cover, and the top of the piston base is also provided with an inwardly folded upper edge for fixing the piston upper cover; the bottom of the piston base is provided with a lower slot adapted to the piston lower cover, and the bottom of the piston base is also provided with an inwardly folded lower edge for fixing the piston lower cover.

[0013] Furthermore, a first sealing ring is provided between the piston cover and the piston rod; a second sealing ring is provided between the piston coil assembly and the piston rod.

[0014] Furthermore, the piston coil assembly is provided with an auxiliary channel for liquid flow, and the piston upper cover and the piston lower cover are both provided with a second through hole that communicates with the auxiliary channel.

[0015] The present invention also provides a magnetorheological vibration damper, including a cylinder assembly and a piston assembly, wherein the piston assembly is as described above for the magnetorheological vibration damper.

[0016] The beneficial effects of this invention are: by opening an annular groove on the working surface of the piston base, the encapsulation layer is embedded in the groove to form an interlocking structure. In particular, by adopting a dovetail or trapezoidal inverted interlocking structure, the mechanical interlocking force between the encapsulation layer and the piston base can be greatly improved, effectively preventing the encapsulation layer from debonding or slipping off completely during high-frequency reciprocating motion.

[0017] The encapsulation layer is made of high-performance materials such as polyetheretherketone (PEEK) filled with carbon fiber or graphite. It is dense and non-porous, which can effectively resist the micro-cutting wear of hard magnetic particles in magnetorheological fluid, and at the same time has good resistance to media corrosion. Moreover, the encapsulation layer material is a low magnetic permeability polymer material, which will not interfere with or shield the magnetic field line distribution inside the shock absorber, ensuring the accuracy of magnetic field control and the linearity of damping force.

[0018] Furthermore, the differentiated design of a deep bottom groove and a wide top groove creates a gradient force characteristic in the axial direction of the encapsulation layer. This provides strong anti-slip anchoring through the deep bottom groove and releases thermal stress and compensates for thermal expansion through the wide top groove, thereby reducing piston jamming and ensuring the long-term stability of the damping force.

[0019] By fixing the upper and lower covers of the piston with upper and lower folded edges, and with the help of the sealing ring design, the internal sealing of the piston assembly is ensured, thus extending the overall service life of the shock absorber. Attached Figure Description

[0020] Figure 1 : A cross-sectional schematic diagram of the piston assembly of the magnetorheological damper provided by the present invention.

[0021] Figure 2 : A cross-sectional view of the piston sleeve;

[0022] Figure 3 : Schematic cross-sectional view of the piston base.

[0023] Reference numerals: 1-Piston rod; 2-Oil reservoir; 3-Piston sleeve; 31-Piston base; 311-Annular groove; 312-Bottom groove; 313-Middle groove; 314-Top groove; 315-Upper slot; 316-Upper folded edge; 317-Lower slot; 318-Lower folded edge; 32-Encapsulation layer; 321-Protrusion; 322-Bottom protrusion; 323-Middle protrusion; 324-Top protrusion; 4-Piston top cover; 41-First sealing ring; 5-Piston bottom cover; 6-Piston coil assembly; 61-Second sealing ring; 62-Auxiliary channel; 7-Channel; 8-First through hole; 9-Second through hole; b-Groove width; h-Groove depth. Detailed Implementation

[0024] The present invention will be further described below.

[0025] This invention provides a piston assembly for a magnetorheological damper, mainly used in magnetorheological fluid dampers. It includes a piston rod 1 and a piston sleeve 3 movably disposed within an oil reservoir 2. The piston sleeve 3 includes a piston base 31 and an encapsulation layer 32. The piston base 31 is hollow internally. A piston top cover 4 is provided at the top of the piston base 31, and a piston bottom cover 5 is provided at the bottom. A piston coil assembly 6 is also provided between the piston top cover 4 and the piston bottom cover 5, located inside the piston base 31. A channel 7 for liquid flow is provided between the outer wall of the piston coil assembly 6 and the inner wall of the piston base 31. Both the piston top cover 4 and the piston bottom cover 5 have a first through hole 8 communicating with the channel 7. The end of piston rod 1 passes through piston upper cover 4 and piston coil assembly 6 in sequence and is sealed to piston lower cover 5. The piston rod 1 is sealed to piston upper cover 4 and piston coil assembly 6. The encapsulation layer 32 is disposed between piston base 31 and oil reservoir 2 and is located in the middle of piston base 31. An annular groove 311 is provided on the outer side of piston base 31 along the length direction of piston base 31. A protrusion 321 adapted to the annular groove 311 is provided on the inner side of encapsulation layer 32. The protrusion 321 is engaged with the annular groove 311. The outer side of encapsulation layer 32 abuts against the inner wall of oil reservoir 2 and moves up and down with piston base 31 along the length direction of oil reservoir 2.

[0026] like Figures 1-3As shown, the piston assembly of the magnetorheological damper includes a piston rod 1 and a piston sleeve 3 movably disposed within an oil reservoir 2. The piston sleeve 3 includes a piston base 31 and an encapsulation layer 32. The piston base 31 is hollow inside, with a piston top cover 4 at the top and a piston bottom cover 5 at the bottom. Between the piston top cover 4 and the piston bottom cover 5, a piston coil assembly 6 is disposed inside the piston base 31. The hollow interior and layered assembly design allow the coil assembly 6 to be compactly encapsulated inside the piston, making full use of the internal space of the piston and facilitating subsequent maintenance and replacement. A gap is left between the outer wall of the piston coil assembly 6 and the inner wall of the piston base 31, forming a channel 7 for the flow of magnetorheological fluid. Both the piston top cover 4 and the piston bottom cover 5 are provided with a first through hole 8 communicating with the aforementioned channel 7. When the piston reciprocates within the cylinder, the magnetorheological fluid can smoothly enter the channel 7 through the first through hole 8 and rapidly change its viscosity under the action of the magnetic field, thereby achieving rapid and precise control of the damping force. The cooperation between channel 7 and the through hole ensures the circulation of liquid and avoids damping failure caused by liquid blockage. The end of piston rod 1 passes through piston upper cover 4 and piston coil assembly 6 in sequence and is sealed to piston lower cover 5. At the same time, piston rod 1 is also sealed to piston upper cover 4 and piston coil assembly 6; preferably, a first sealing ring 41 is provided between piston upper cover 4 and piston rod 1, and a second sealing ring 61 is provided between piston coil assembly 6 and piston rod 1; the multi-seal design can effectively prevent magnetorheological fluid from leaking from the gaps between piston rod 1 and other components, ensuring the stability of internal pressure and the long-term reliability of damping force of the shock absorber, while avoiding environmental pollution from leakage. Encapsulation layer 32 is disposed between piston base 31 and oil reservoir 2, and is located in the middle of piston base 31, for contacting and sealing the inner wall of oil reservoir 2; an annular groove 311 is provided on the outer side of piston base 31 along its length direction, and a protrusion 321 adapted to the annular groove 311 is provided on the inner side of encapsulation layer 32. The protrusion 321 is embedded in the annular groove 311 to form an interlocking connection. This physical interlocking significantly increases the contact area and mechanical locking force between the encapsulation layer 32 and the substrate, effectively preventing the encapsulation layer 32 from slipping or shifting during long-term high-frequency reciprocating motion. The outer surface of the encapsulation layer 32 abuts against the inner wall of the oil reservoir 2 and moves up and down along the length of the oil reservoir 2 together with the piston substrate 31. In practical applications, when the piston assembly reciprocates at high frequency in the magnetorheological fluid, the encapsulation layer 32 directly rubs against the inner wall of the oil reservoir 2. Furthermore, the encapsulation layer 32 is made of highly wear-resistant materials such as polyetheretherketone (PEEK) filled with carbon fiber or graphite, effectively resisting the cutting action of hard magnetic powder and preventing direct wear on the piston substrate 31. More importantly, PEEK material is a low-permeability polymer material that does not interfere with the distribution of magnetic lines of force inside the damper, ensuring the accuracy of magnetic field control and the linearity of the damping force.The piston assembly of this magnetorheological damper significantly improves the adhesion of the encapsulation layer 32 through the interlocking structure between the piston base 31 and the encapsulation layer 32, preventing the encapsulation layer 32 from falling off and cracking, ensuring excellent overall wear and corrosion resistance, and meeting both wear resistance and insulation requirements. It has strong structural stability and wide adaptability to working conditions, effectively solving the problems of easy failure of traditional piston surface protection and large magnetic field interference, and greatly improving the overall service life and operational stability of the magnetorheological damper.

[0027] To further enhance the bonding force, the structure of the annular groove 311 in this embodiment has been optimized. Specifically, the annular groove 311 includes a bottom groove 312, a middle groove 313, and a top groove 314 arranged sequentially from bottom to top. The bottom groove 312 is located at the end of the piston base 31 near the piston lower cover 5, and the depth of the bottom groove 312 is greater than the depth of the middle groove 313 and the top groove 314. The top groove 314 is located at the end of the piston base 31 near the piston upper cover 4, and the width of the top groove 314 is greater than the width of the middle groove 313 and the bottom groove 312. The protrusion 321 includes a bottom protrusion 322, a middle protrusion 323, and a top protrusion 324 corresponding to the bottom groove 312, the middle groove 313, and the top groove 314, respectively. The bottom groove 312 is located at the end of the piston base 31 near the piston lower cover 5, and its depth is greater than the depth of the middle groove 313 and the top groove 314. During the compression stroke, the bottom region of the piston typically bears the greatest fluid back pressure and impact force. The bottom groove 312 is deeper to increase the mechanical blocking area of ​​the encapsulation layer 32 in the axial direction, forming a stronger anchoring structure and effectively preventing the encapsulation layer 32 from slipping off the bottom or being pulled up by the roots under the impact of high-pressure fluid. The top groove 314 is located at the end of the piston base 31 near the piston cap 4, and its width is greater than that of the middle groove 313 and the bottom groove 312. When the piston assembly and the oil reservoir 2 experience intense friction, causing the encapsulation layer 32 to expand due to heat, the wider top groove 314 can provide a larger accommodating space and deformation buffer margin for the encapsulation layer 32, effectively releasing thermal stress, compensating for thermal expansion, preventing the encapsulation layer 32 from cracking due to stress concentration, and reducing piston assembly jamming, thus ensuring the long-term stability of the damping force.

[0028] As a further improvement, the cross-sections of the bottom groove 312, the middle groove 313, and the top groove 314 all adopt a dovetail or trapezoidal structure, with the groove opening width being smaller than the groove bottom width, forming a physical inverted interlock. Once the protrusion 321 of the encapsulation layer 32 is embedded in the annular groove 311, it is firmly locked and difficult to pull out even under severe axial shear force, achieving the ultimate bonding strength of mechanical interlocking.

[0029] In particular, the cross-section of the bottom groove 312 further adopts a dovetail structure with a rounded transition. While maintaining the advantages of the undercut, it eliminates sharp stress concentration points and avoids microcracks caused by stress concentration under long-term fatigue conditions, thereby significantly improving fatigue resistance and overall service life.

[0030] Furthermore, at least two central grooves 313 are evenly distributed. Multiple central grooves 313 can provide uniformly distributed adhesion, avoid stress concentration in a single area, and at the same time, will not excessively weaken the overall strength of the piston substrate 31, making the bonding between the encapsulation layer 32 and the substrate more uniform and reliable.

[0031] In terms of manufacturing, to enhance the bonding strength between the encapsulation layer 32 and the piston substrate 31, the encapsulation layer 32 is made of polyetheretherketone (PEEK) filled with carbon fiber or graphite; the surface of the annular groove 311 is sandblasted. Specifically, before the encapsulation layer 32 is formed, the annular groove 311 on the surface of the piston substrate 31 can be sandblasted to increase surface roughness. Subsequently, the carbon fiber or graphite-filled PEEK material is heated and melted, and then completely encapsulated in the annular groove 311 and the working surface of the piston substrate 31 by injection molding. After cooling, a dense and wear-resistant encapsulation layer 32 is formed. Sandblasting provides microscopic mechanical interlocking, while injection molding ensures seamless adhesion between the encapsulation layer 32 and the substrate. The combination of the two forms an integrated structure between the encapsulation layer 32 and the piston substrate 31, eliminating the risk of the encapsulation layer 32 falling off and cracking.

[0032] To ensure a stable connection between the piston upper cover 4, piston lower cover 5, and piston base 31, the piston base 31 has an upper slot 315 adapted to the piston upper cover 4 at its top, and an inwardly folded upper flange 316 at its top for clamping and fixing the piston upper cover 4. Similarly, the piston base 31 has a lower slot 317 adapted to the piston lower cover 5 at its bottom, and an inwardly folded lower flange 318 at its bottom for fixing the piston lower cover 5. This slot-and-flanged assembly method is simple and compact, achieving reliable fixing without additional fasteners, reducing assembly costs, and ensuring the secure encapsulation of the internal piston coil assembly 6.

[0033] To increase the flow path of the liquid, the response speed of the magnetorheological fluid is improved, such as... Figure 1 As shown, an auxiliary channel 62 can also be opened inside the piston coil assembly 6, which, together with the second through hole 9 on the piston upper cover 4 and lower cover, further optimizes the internal liquid circulation, improves the response speed of the magnetorheological fluid, and makes the control of damping force more sensitive.

[0034] This invention also provides a magnetorheological vibration damper, including a cylinder assembly and a piston assembly, wherein the piston assembly adopts the piston assembly of the magnetorheological vibration damper as described above. Through the interlocking structure of the annular groove 311 and the protrusion 321, the shape design of the annular groove 311, the differentiated size design, and the encapsulation layer 32 made of high wear-resistant material, the problems of poor bonding force, large magnetic field interference, and easy wear of traditional piston surface protection structures are comprehensively solved, significantly improving the overall service life and operational stability of the magnetorheological vibration damper.

Claims

1. A piston assembly for a magneto-rheological damper, the piston assembly comprising: The piston includes a piston rod (1) and a piston sleeve (3) movably disposed within an oil reservoir (2). The piston sleeve (3) includes a piston base (31) and an encapsulation layer (32). The piston base (31) is hollow inside. A piston top cover (4) is provided at the top of the piston base (31), and a piston bottom cover (5) is provided at the bottom of the piston base (31). A piston coil assembly (6) located inside the piston base (31) is also provided between the piston top cover (4) and the piston bottom cover (5). A channel (7) for liquid flow is provided between the outer wall of the coil assembly (6) and the inner wall of the piston base (31). The piston upper cover (4) and the piston lower cover (5) are each provided with a first through hole (8) that communicates with the channel (7). The end of the piston rod (1) passes through the piston upper cover (4) and the piston coil assembly (6) in sequence and is sealed to the piston lower cover (5). The piston rod (1) is sealed to the piston upper cover (4) and the piston rod (1) is sealed to the piston coil assembly (6). The encapsulation layer (32) is disposed between the piston base (31) and the oil reservoir (2) and is located in the middle of the piston base (31). An annular groove (311) is provided on the outer side of the piston base (31) along the length direction of the piston base (31). A protrusion (321) adapted to the annular groove (311) is provided on the inner side of the encapsulation layer (32). The protrusion (321) is engaged with the annular groove (311). The outer side of the encapsulation layer (32) abuts against the inner wall of the oil reservoir (2) and moves up and down along the length direction of the oil reservoir (2) with the piston base (31).

2. A piston assembly for a magneto-rheological damper as defined in claim 1, wherein: The annular groove (311) includes a bottom groove (312), a middle groove (313), and a top groove (314) arranged sequentially from bottom to top. The bottom groove (312) is located at one end of the piston base (31) near the piston lower cover (5), and the depth of the bottom groove (312) is greater than the depth of the middle groove (313) and the top groove (314). The top groove (314) is located at one end of the piston base (31) near the piston upper cover (4), and the width of the top groove (314) is greater than the width of the middle groove (313) and the bottom groove (312). The protrusion (321) includes a bottom protrusion (322), a middle protrusion (323), and a top protrusion (324) corresponding to the bottom groove (312), the middle groove (313), and the top groove (314), respectively.

3. A piston assembly for a magneto-rheological damper as defined in claim 2, wherein: The bottom groove (312), middle groove (313) and top groove (314) all have dovetail or trapezoidal cross sections, and their groove opening width is smaller than the groove bottom width, forming an inverted structure that interlocks with the encapsulation layer (32).

4. A magneto-rheological damper piston assembly as claimed in claim 3, wherein: The bottom groove (312) has a dovetail-shaped structure with a rounded transition.

5. A piston assembly for a magneto-rheological fluid damper as defined in claim 2 wherein: The central groove (313) is evenly distributed with at least two grooves.

6. A piston assembly for a magneto-rheological damper as defined in claim 1, wherein: The encapsulation layer (32) is made of polyetheretherketone filled with carbon fiber or graphite; the surface of the annular groove (311) is sandblasted.

7. The piston assembly of a magnetorheological damper as described in claim 1, characterized in that: The piston base (31) has an upper slot (315) adapted to the piston upper cover (4) at the top, and the piston base (31) also has an inwardly folded upper edge (316) for fixing the piston upper cover (4) at the top; the piston base (31) has a lower slot (317) adapted to the piston lower cover (5) at the bottom, and the piston base (31) also has an inwardly folded lower edge (318) for fixing the piston lower cover (5) at the bottom.

8. The piston assembly of a magnetorheological damper as described in claim 1, characterized in that: A first sealing ring (41) is provided between the piston top cover (4) and the piston rod (1); a second sealing ring (61) is provided between the piston coil assembly (6) and the piston rod (1).

9. The piston assembly of a magnetorheological damper as described in claim 1, characterized in that: The piston coil assembly (6) is also provided with an auxiliary channel (62) for liquid flow. The piston upper cover (4) and the piston lower cover (5) are both provided with a second through hole (9) that communicates with the auxiliary channel (62).

10. A magnetorheological damper, comprising a cylinder assembly and a piston assembly, characterized in that: The piston assembly is the piston assembly of the magnetorheological damper as described in any one of claims 1-9.

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