Buffering sealing support ring of hydraulic cylinder

Abstract

A seal assembly (18) for a hydraulic cylinder piston rod (12) of a hydraulic cylinder (10) includes an annular cushion seal (22) and an annular support ring (24). A first axial pressure side of the annular cushion seal (22) faces a rod end chamber of the hydraulic cylinder (10) and fits near a first axial side surface of an annular groove (21) defined in a rod end (16) of the hydraulic cylinder (10) through which the piston rod (12) passes, a second axial sealing side opposite the first axial pressure side includes a radially outer annular sealing surface (224) and a radially inner annular sealing surface (225), where the radially outer annular sealing surface (224) is spaced further from the first axial pressure side of the annular buffer seal (22) than the radially inner annular sealing surface (225) of the buffer seal (22). Such that an annular recess is formed on the second axial sealing side of the annular cushion seal around the inner diameter of the annular cushion seal. The annular support ring includes a radially extending leg and an axially extending leg, the radially extending leg extending substantially along an entire radial extent of a radially outer annular sealing surface of the annular cushion seal, the axially extending legs extend axially on a second axial sealing side of the annular cushioning seal into an annular recess formed around an inner diameter of the annular cushioning seal.

Description

Technical Field

[0001] The present invention relates to a sealing assembly for a hydraulic cylinder, and more particularly to a sealing assembly comprising an annular buffer seal and an annular support ring extending along a radial extent of a sealing surface of the buffer seal. Background Art

[0002] Many work machines, such as tractors, excavators, loaders, and other earth-moving equipment, utilize hydraulic actuators to generate the forces and relative movement of various parts of the machine required to accomplish their tasks. These hydraulic actuators, which include, for example, hydraulic cylinders and fluid motors, typically include two fluid chambers disposed on opposite sides of a movable element. Pressurized fluid is introduced into one of the fluid chambers, which causes the movable element to move relative to the hydraulic actuator housing.

[0003] The movable element is usually connected to a work tool or other machine component on the work machine by a rod or shaft. Typically, each hydraulic actuator includes a sealing device engaged with the rod or shaft to prevent pressurized fluid from leaking from the fluid chamber of the hydraulic actuator during use. One such sealing device for a hydraulic cylinder is described in U.S. Patent No. 6,129,358, which describes a one-way rod sealing ring suitable for forming a sealed state.

[0004] A sealing arrangement for a hydraulic cylinder may include a series of seals disposed in a cap or flange at a rod end of a barrel of the hydraulic cylinder to engage a shaft or piston rod near an exit point of the piston rod. The cap and / or flange at the rod end of the barrel may include a series of annular grooves or counterbores axially spaced along a radially inner circumferential surface of the rod end of the barrel, wherein the annular grooves are configured to receive each seal.

[0005] An annular groove in the cylinder head and / or flange at the rod end of the cylinder barrel of a hydraulic cylinder, which is adapted to receive various seals, may be damaged when the hydraulic cylinder is being used in an aggressive application, such as a hydraulic cylinder used as a boom, rod or bucket cylinder on a machine such as an excavator, crawler tractor, or a large wheel loader operating in an application such as coal mining, bauxite, iron ore or other minerals. Other applications of heavy machinery in earth moving operations may also expose the hydraulic cylinders used on the heavy machinery to move the various parts of the machine relative to each other and relative to the working surface to abrasive materials that may pass through one or more seals in the seal array located between the piston rod and the cylinder head of the hydraulic cylinder. The seal array may be designed to prevent the pressurized hydraulic fluid within the hydraulic cylinder from leaking outwardly between the piston rod and the cylinder head, and to prevent material from contaminating the piston rod side chamber (also referred to as the "rod end" chamber or "cap end" chamber) on the side of the hydraulic cylinder where the piston rod exits the cylinder. In some applications, contaminants may collect between the sealing surface of the seal and the surface of the annular groove in the cylinder head and / or the flange at the rod end of the cylinder barrel adapted to receive the seal. These contaminants may become embedded in the face of the seal that engages the surface of the annular groove in the cylinder head and / or flange, and during operation of the hydraulic cylinder, over time, relative movement between the seal with the embedded abrasive contaminants and the annular groove may cause a portion of the annular groove (typically formed in the metal material of the cylinder head and / or flange at the rod end of the cylinder barrel) to be worn away, thereby creating an undesirable step or gap near the seal, which may ultimately lead to failure of the seal and leakage of the hydraulic cylinder.

[0006] Exemplary embodiments of various disclosed seal assemblies, and arrangements of seals and wear guides for use in hydraulic cylinders to provide sealing engagement between a piston rod of the hydraulic cylinder and a cylinder head and / or flange at the rod end of a cylinder barrel of the hydraulic cylinder are intended to address all or some of the above-mentioned issues. Summary of the invention

[0007] In one aspect, the present invention relates to a sealing assembly for a hydraulic cylinder piston rod of a hydraulic cylinder. The sealing assembly includes an annular buffer seal including a first axial pressure side and a second axial sealing side opposite to the first axial pressure side, the first axial pressure side being configured to face the rod end chamber of the hydraulic cylinder and being assembled near a first axial side surface of an annular groove defined in the rod end of the hydraulic cylinder through which the piston rod passes, the second axial sealing side including a radially outer annular sealing surface and a radially inner annular sealing surface, wherein the radially outer annular sealing surface is spaced further from the first axial pressure side of the annular buffer seal than the radially inner annular sealing surface of the buffer seal, so that an annular recess is formed on the second axial sealing side of the annular buffer seal around the inner diameter of the annular buffer seal. The seal assembly also includes an annular support ring including a radially extending leg portion and an axially extending leg portion, the radially extending leg portion being configured to extend along substantially the entire radial extent of the radially outer annular sealing surface of the annular buffer seal, the axially extending leg portion being adjacent to the radially extending leg portion and being configured to extend axially into an annular recess formed around an inner diameter of the annular buffer seal on a second axial sealing side of the annular buffer seal.

[0008] In another aspect, the present invention relates to a hydraulic cylinder including a cylinder barrel, a cylinder head and a flange at a rod end of the barrel, a piston rod extending through the rod end of the cylinder barrel and configured to move axially relative to the rod end of the cylinder barrel, and a plurality of seals disposed in axially spaced annular grooves formed around the inner circumferential surface of the rod end of the cylinder barrel and configured to seal with the piston rod. One of the plurality of seals is a buffer seal assembly, the buffer seal assembly including an annular buffer seal including a first axial pressure side and a second axial sealing side opposite to the first axial pressure side, the first axial pressure side being configured to face the rod end chamber of the hydraulic cylinder and fitted near a first axial side surface of an annular groove defined in the rod end of the cylinder barrel through which the piston rod passes, the second axial sealing side including a radially outer annular sealing surface and a radially inner annular sealing surface, wherein the radially outer annular sealing surface is spaced further from the first axial pressure side of the annular buffer seal than the radially inner annular sealing surface of the buffer seal, so that an annular recess is formed around the inner diameter of the annular buffer seal on the second axial sealing side of the annular buffer seal. The buffer seal assembly also includes an annular support ring including a radially extending leg and an axially extending leg, the radially extending leg being configured to extend along substantially the entire radial extent of the radially outer annular sealing surface of the annular buffer seal, the axially extending leg being adjacent to the radially extending leg and being configured to extend axially on a second axial sealing side of the annular buffer seal into an annular recess formed around an inner diameter of the annular buffer seal.

[0009] In yet another aspect, the present invention relates to a hydraulic cylinder comprising a barrel, a cylinder head and a flange at a rod end of the barrel, and a piston rod extending through the rod end of the barrel and configured to move axially relative to the rod end of the barrel. The rod end of the barrel comprises a plurality of axially spaced annular grooves formed around an inner circumferential surface of the rod end of the barrel, each axially spaced annular groove being configured to support a sealing member configured to sealably engage the piston rod. One of the multiple seals is a buffer seal assembly, which includes an annular buffer seal, which includes a first axial pressure side and a second axial sealing side opposite to the first axial pressure side, the first axial pressure side being configured to face the rod end chamber of the hydraulic cylinder and being assembled near a first axial side surface of an annular groove defined in the rod end of the cylinder through which the piston rod passes, the second axial sealing side including a radially outer annular sealing surface and a radially inner annular sealing surface, wherein the radially outer annular sealing surface is spaced farther from the first axial pressure side of the annular buffer seal than the radially inner annular sealing surface of the buffer seal, so that an annular recess is formed around the inner diameter of the annular buffer seal on the second axial sealing side of the annular buffer seal. One of these axially spaced annular grooves is configured for supporting an annular support ring of the buffer seal assembly, wherein the annular support ring includes a radially extending leg and an axially extending leg, the radially extending leg is configured to extend along substantially the entire radial extent of the radially outer annular sealing surface of the annular buffer seal, the axially extending leg is adjacent to the radially extending leg and is configured to extend axially into an annular recess formed around the inner diameter of the annular buffer seal on a second axial sealing side of the annular buffer seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a partially cut-away perspective view of a hydraulic cylinder according to an embodiment of the present invention, the hydraulic cylinder including an array of seals between a piston rod and a cylinder head of the hydraulic cylinder;

[0011] Figure 2 is a radial cross-sectional view of a segment of an annular buffer seal assembly that can be used to seal between a piston rod and a cylinder head according to an embodiment of the present invention;

[0012] Figure 3 is a partial cross-sectional view of a sealing device for a hydraulic cylinder piston rod and a cylinder head according to an embodiment of the present invention, comprising Figure 2 The buffer seal assembly shown; and

[0013] Figure 4 is a partial cross-sectional view of a sealing device for a hydraulic cylinder piston rod and a cylinder head according to an embodiment of the present invention. DETAILED DESCRIPTION

[0014] With reference to the accompanying drawings, Figure 1 An exemplary hydraulic cylinder 10 is shown having a piston rod 12 attached at one axial end to a piston 13 slidably disposed within a cylinder barrel 14. The piston rod 12 is axially movable by a cylinder head that is bolted to a flange at a rod end 16 of the cylinder barrel 14 by a plurality of bolts 15. The rod end 16 of the cylinder barrel 14 is located at the axial end of the cylinder barrel 14 opposite the blind end or closed cap end 11 of the cylinder barrel 14. Figure 2-4 As shown in more detail in , the piston rod 12 is slidably engaged with an array 18, 318, 418 of annular piston rod seals and wear guides along the circumferential outer circumference of the piston rod 12, which are axially spaced along the radially inner circumferential surface of the cylinder head and / or flange at the rod end 16, 316, 416 of the cylinder barrel 14. In various exemplary embodiments, the array of annular piston rod seals and wear guides may be disposed in axially spaced annular grooves formed around the radially inner circumferential surface of one or both of the cylinder head and the flange at the rod end 16, 315, 416 of the cylinder barrel 14. References throughout the specification to the radially inner circumferential surface of the rod end of the cylinder barrel refer to the radially inner circumferential surface of the flange at the rod end of the cylinder barrel and the radially inner circumferential surface of the cylinder head bolted to the flange at the rod end of the cylinder barrel.

[0015] The annular piston rod seal closest to the pressurized rod end chamber of the hydraulic cylinder 10 can be a buffer seal assembly, which includes an annular buffer seal 22, 350 and an annular support ring 24, 352, such as Figure 2 and 3 As shown. The buffer seal 22, 350 and the support ring 24, 352 can be installed in an operating position in the rod end 16, 316 of the hydraulic cylinder 12, in an annular groove 21, 351 extending around the radial inner circumferential surface of the rod end 16, 316, for slidable engagement with the piston rod 12 axially movable therein. The annular groove 21, 351 can have a width 27 and a depth 25. The hydraulic cylinder 12 is an exemplary hydraulic cylinder for various purposes related to tractors, earth-moving equipment, etc. Some exemplary applications of hydraulic cylinders including buffer seal assemblies according to embodiments of the present invention may include hydraulic cylinders for performing one or more operations, such as extending, retracting, lifting, tilting, rotating, and performing other movements of various components on heavy machinery, such as booms, rods and buckets of excavators, or other components of machines, such as large wheel loaders, hydraulic mining shovels, large crawler tractors, and other equipment.

[0016] like Figure 2As shown in the exemplary embodiment of , the buffer seal 22 can be an annular elastomeric ring formed of an elastomeric material such as polyurethane or rubber, and is configured to fit within the annular groove 21 formed around the radial inner circumferential surface of the rod end 316. The annular buffer seal 22 can include a first axial pressure side formed with a plurality of adjacent axially facing pressure surfaces 220, 221, 222, and 223 facing the pressurized rod end chamber of the hydraulic cylinder 12, and an opposite second axial sealing side formed with a plurality of adjacent axially facing sealing surfaces 224, 225 facing the exterior of the hydraulic cylinder and configured to contact the support ring 24, 352 in a mating, cooperative relationship within the annular groove 21. The first axial pressure side of the annular buffer seal 22 includes a radially outer annular pressure surface 220 joined to a radially inner annular pressure surface 223 by two continuous and converging tapered pressure surfaces 221, 222, which together define an annular concave recess 23 in the first axial pressure side of the buffer seal 22. The buffer seal also includes a radially outer circumferential surface 226 configured to contact the bottom of the annular groove 21, 351, or positioned near the bottom of the annular groove 21, 351, and a radially inner circumferential surface 227 configured to contact the piston rod 12, which is axially movable within the rod end 16, 316.

[0017] The pressure surfaces 221, 222 may be axially tapered, linear, or curved surfaces that converge to define an annular concave recess 23 in the first axial pressure side of the annular buffer seal 22, wherein the recess 23 separates a radially outer annular leg having the pressure surface 221 and terminating in the axially facing annular pressure surface 220 from a radially inner annular leg having the pressure surface 222 and terminating in the axially facing annular pressure surface 223. Pressure applied to the annular recess 23 may cause the radially outer annular leg to bend radially outward and press against the bottom surface of the annular groove 21, and cause the radially inner annular leg to bend radially inward and press against the piston rod 12. The radially outer circumferential surface 226 of the buffer seal 22 may be configured to have multiple portions along its axial length that are located near or in contact with the bottom of the annular groove 21, in some cases leaving a small gap between some of these portions of the radially outer circumferential surface 226 and the bottom of the annular groove 21 when the pressure applied to the annular recess 23 drops below a certain threshold. Similarly, in various embodiments of the annular buffer seal 22 according to the present invention, the radially inner circumferential surface 227 of the buffer seal 22 is configured to have a portion that contacts the radially outer circumferential surface of the piston rod 12 along its axial length or its entire axial length. Portions of one or both of the radially outer circumferential surface 226 and the radially inner circumferential surface 227 of the buffer seal 22 may remain spaced apart from the annular groove 21 and the bottom of the piston rod 12, respectively, when the piston rod 12 moves axially to extend and retract relative to the rod end 316 and the hydraulic cylinder 10, depending on the amount of pressure applied to the annular recess 23 from the pressurized rod end chamber of the hydraulic cylinder 10 in some cases. Higher pressures above a certain predetermined threshold that may be introduced into the annular recess 23 from the rod end chamber of the hydraulic cylinder 10 may cause one or both of the radially outer annular leg having the pressure surface 221 and the radially inner annular leg having the pressure surface 222 to flex, thereby creating a tighter seal between one or more portions of the annular buffer seal 22 and the annular groove 21 and / or the piston rod 12.

[0018] like Figure 2As shown, the buffer seal 22 can cooperate with the support ring 24 along the axially facing sealing surfaces 224, 225, and the assembly of the buffer seal 22 and the support ring 24 can be cooperatively received in the annular groove 21 formed in the radial inner circumferential surface of the rod end 16, 316, 416 of the hydraulic cylinder 12. The axially facing annular sealing surface 224 of the buffer seal 22 can be disposed at a greater distance from the first axial pressure side of the annular buffer seal 22 than from the axially facing annular sealing surface 225 of the buffer seal 22, so that an annular step or recess is formed around the inner diameter of the annular buffer seal 22 on the axial sealing side of the annular buffer seal 22 at the location where the axially facing sealing surface 224 engages the axially facing sealing surface 225. The axially facing sealing surface 224 can be formed with a raised radius R1 at the entrance of the recess, and the raised radius R1 is predetermined to avoid the creation of a higher stress area at the entrance of the recess.

[0019] The support ring 24 may be formed with a radially extending leg 26 configured to extend substantially along the entire radial extent of the axially facing sealing surface 224 of the buffer seal 22. The radially extending leg 26 may terminate in a chamfered outer circumferential surface 247 having a raised radius R3 formed on a radially outer edge of the support ring on a side facing away from the buffer seal 22. Reference to substantially the entire radial extent means at least 50%-75% of the radial extent of the axially facing sealing surface 224 of the buffer seal 22. The increased surface area of ​​the support ring 24 in contact with the radially outermost sealing surface 224 of the buffer seal 22 reduces the contact force at any point along the interface between the support ring 24 and the buffer seal 22 compared to conventional arrangements, thereby reducing any wear resulting from abrasion between the two components, as well as facilitating assembly of the support ring with the buffer seal 22 in the proper orientation. The support ring 24 may be formed with an axially extending leg 28 adjacent to the radially extending leg 26 and configured to extend axially into an annular recess formed at the intersection of the axially facing sealing surfaces 224, 225 of the buffer seal 22. The axially extending leg 28 of the support ring 24 may be configured to cooperate with the annular recess of the buffer seal 22 along the radial outer surface 243, the axial end surface 244 and the radial inner surface 245, wherein the radial inner surface 245 of the axially extending leg 28 is configured to contact or seat with a small spacing with the outer circumferential surface of the piston rod 12 passing through the buffer seal assembly. In some exemplary embodiments of the present invention, the radially extending leg 26 may have a portion of a thickness 29 falling within a range of from about 1 mm to about 4 mm in a direction substantially parallel to the piston rod 12. The surfaces 241, 243 at the intersection of the radially extending legs 26 and the axially extending legs 28 of the support ring 24 may be formed with a concave radius R2 that mates with a convex radius R1 at the entrance of an annular recess formed around the inner diameter of the annular buffer seal 22 on the axial sealing side of the annular buffer seal 22. The opposing surfaces 246, 245 at the intersection of the radially extending legs 26 and the axially extending legs 28 may be formed with a convex radius R4, which also avoids the creation of any higher stress areas that may otherwise be created if the support ring 24 is formed with sharp corners or circumferential edges. In some exemplary embodiments, each of the radii R1, R2, R3, and R4 can be predetermined based on the type of material used for the buffer seal 22 and the support ring 24, the fluid pressure that will be applied to one or both of the buffer seal 22 and the support ring 24, the overall size of the buffer seal 22 and the support ring 24, and one or more other factors that may affect the hoop stress and other stresses experienced by the components under different operating conditions.As one non-limiting example, each of the radii R1 , R2 , R3 , and R4 may be predetermined to have a value greater than or equal to half of a thickness of a corresponding portion in a region forming the corresponding radius.

[0020] An optional embodiment of the present invention may include a cushioning seal 22 having a Figure 2 A shallower notch formed around the inner diameter of the buffer seal as shown in the exemplary embodiment of the present invention, or another interconnection configuration between the buffer seal and the support ring. Figure 2 While the recess is shown having a sharp corner at the bottom of the recess, an alternative interconnection configuration between the buffer seal and the back-up ring may include axially tapered or curved surfaces on the axial sealing side of the buffer seal and on the mating surface of the back-up ring.

[0021] In some exemplary embodiments, the support ring 24 may be made of a harder and stronger material than the material used for the cushion seal 22. Examples of suitable materials for the support ring 24 may include polytetrafluoroethylene (PTFE), acetal (POM), nylon, and other rigid plastic materials, composites, or matrices. The cushion seal 22 may be formed of materials such as polyurethane, rubber, or other elastomers.

[0022] Under non-low load or pressure conditions, there may be a gap between at least a portion of the radially inner surface 245 of the axially extending leg 28 of the support ring 24 and the outer circumferential surface of the piston rod 12. This gap may provide area or distance for some displacement of the support ring 24 during higher pressure applications. This displacement area may also absorb energy generated by hoop stresses in the support ring 24 and reduce the overall contact force and friction between the support ring 24 and the buffer seal 22. Figure 2 In the exemplary embodiment shown, the support ring 24 is configured such that the axially extending leg 28 engages in an annular recess formed at the intersection of the axially facing sealing surfaces 224, 225 of the buffer seal 22, and the radially extending leg 26 extends along substantially the entire radial extent of the axially facing sealing surface 224 of the buffer seal 22, so that the support ring 24 provides optimal extrusion resistance to the buffer seal 22. The cooperative mating relationship between the support ring 24 and the buffer seal 22 also maintains an optimal stress distribution in the area of ​​the support ring 24 by substantially limiting deformation of the buffer seal 22 relative to the support ring 24. The support ring 24, which is made of a stronger material relative to the buffer seal 22, is able to accommodate greater forces associated with increased pressure on the buffer seal assembly than a support ring that does not have a support ring or does not extend along substantially the entire radial extent of the axially facing sealing surface 224 of the buffer seal 22. As described above, the reference to "substantially the entire radial extent" means 50%-75% or more of the radial extent of the axially facing surface 224 of the buffer seal 22.

[0023] like Figure 1 , 3 As shown in Figures 4 and 5, the buffer seal assembly according to various embodiments of the present invention may be used as part of an arrangement of piston rod seals axially spaced apart along the inner circumferential surface of the rod end 16, 316, 416 of the hydraulic cylinder 10 to form a sealing assembly between the piston rod 12 and the rod end 16, 316, 416. A rod end chamber may be formed between the piston 13 and the rod end 16, 316, 416 in the barrel 14 of the hydraulic cylinder 10. Figure 3 and Figure 4 As shown in , the rod end 16, 316, 416 of the hydraulic cylinder 10 according to different embodiments of the present invention may include, in order from the rod end chamber in the hydraulic cylinder 10 to the axial end surface of the rod end 16, 316, 416 through which the piston rod 12 extends: a cylindrical metal wear guide 360, 460, which is seated in an annular groove 361, 461 formed on the inner circumferential surface of the cylinder head and / or the flange around the rod end 16, 316, 416 of the hydraulic cylinder 10; a buffer seal assembly having a ring groove 21, 351, 451; and a buffer seal assembly having a ring groove 21, 351, 451. The invention relates to a buffer seal 22, 350, 450 and a support ring 24, 352, 452 inside; a U-cup seal 340, 440, which is seated in annular grooves 341, 441; a cylindrical wear guide 330, 430, which is made of a rigid plastic material and is seated in annular grooves 331, 431; and a three-lip wipe seal 320, 420, which includes three annular lips 322, 422; 324, 424; and 326, 426; which are located in annular grooves or multiple adjacent annular grooves 321, 421.

[0024] Each of the wear guide, buffer seal assembly, U-cup seal, and triple lip wiper seal may engage the outer circumferential surface of the piston rod 12 as the piston rod 12 moves axially within the cylinder head to extend and retract relative to the hydraulic cylinder. The metal wear guides 360, 460 and the wear guides 330, 430 are made of plastic materials such as polytetrafluoroethylene (PTFE), acetal (POM), nylon, and other rigid plastic materials, composite materials, or matrices, and in addition to providing an additional sealing interface between the piston rod and the cylinder head, may also help to maintain the piston rod in a centered position within the buffer seal assembly, U-cup seal, and wiper seal. Each wear guide may include one or more annular rings disposed in one or more annular grooves formed in the inner circumferential surface of the cylinder head and / or flange at the rod end 16, 316, 416 of the hydraulic cylinder 10. The buffer seal assembly having the buffer seal 22, 350, 450 and the support ring 24, 352, 452 is the seal located closest to the rod end chamber in the barrel 14. The three-lip wiper seal 320, 420 is the outermost seal. U-cup seals 340, 440 and wear guides 330, 430 made of polytetrafluoroethylene (PTFE), acetal (POM), nylon and other rigid plastic materials, composites or matrices can be disposed between the buffer seal assembly and the wiper seal.

[0025] One function of the buffer seal assembly is to create a high pressure seal to prevent fluid from escaping from the rod end chamber, the seal of the buffer seal assembly is axially adjacent to the metal wear guides 360, 460 and is closest to the rod end chamber among the three seal rings. However, it is expected that some fluid may leak through the buffer seal assembly along the outer circumferential surface of the piston rod 12.

[0026] The U-cup seals 340, 440 provide a second barrier to prevent fluid from leaking out of the hydraulic cylinder 10. Any fluid that leaks through the buffer seal assembly can be scraped off the outer circumferential surface of the piston rod 12 by the lips of the U-cup seals 340, 440. The fluid can collect in the recess formed in the U-cup seals 340, 440. When the fluid pressure in the rod end chamber drops to a relatively low level, the fluid pressure in the recess formed in the U-cup seal can act on the buffer seals 350, 450 to cause the lip of the buffer seal 22 (the portion of the surface 227 at the distal end of the radially inner annular leg of the buffer seal, which has a Figure 2 The pressure surface 222 in the piston rod and terminating in the axially facing annular pressure surface 223) is disengaged from the outer circumferential surface of the piston rod 12. The disengagement of the buffer seal from the outer circumferential surface of the piston rod allows the trapped fluid to return to the rod end chamber of the hydraulic cylinder.

[0027] One function of the three-lip wiper seal 320, 420 as the outermost seal is to prevent dirt and debris from contaminating the fluid of the hydraulic cylinder. The wiper seal can be forcibly fitted into the annular groove 321, 421. When the three-lip wiper seal 320, 420 is located in the annular groove 321, 421 in the rod end 316, 416, the piston rod 12 can be inserted through the central opening in the wiper seal. The central opening through the wiper seal is configured to have a close tolerance with the outer circumferential surface of the piston rod so that each lip of the three-lip wiper seal forms a compression seal with the outer circumferential surface of the piston rod 12. In other words, the insertion of the piston rod 12 through the opening in the wiper seal causes each of the lips 322, 324, 326 to exert a force on the outer circumferential surface of the piston rod 12, thereby creating a seal. The cutout adjacent to each lip of the three-lip wiper seal provides an area into which each main body portion of each lip can be bent when the piston rod 12 passes through the wiper seal. This flexing action of the main body portion of each wiper seal lip reduces the amount of compression in the respective main body portion, and therefore reduces the amount of force applied by each lip on the outer circumferential surface of the piston rod, without significantly reducing the contact area of ​​the lip on the outer circumferential surface of the piston rod 12. In this way, the wiper seal forms an effective seal with the outer circumferential surface of the piston rod as the piston rod slides within the cylinder housing, without excessively wearing the surface of the piston rod.

[0028] Industrial Applicability

[0029] The present invention relates to a buffer seal assembly including an annular buffer seal and an assembled support ring, and an overall arrangement of axially spaced annular seals and annular wear guides disposed in an annular groove formed in the inner circumferential surface of a cylinder head of a hydraulic cylinder. The arrangement of axially spaced annular seals and annular wear guides may or may not include the disclosed buffer seal assembly. In an arrangement including the buffer seal assembly, the buffer seal 22 may cooperatively cooperate with the support ring 24 and be located in an annular groove formed in the inner circumferential surface of the cylinder head and / or flange of the rod end of the hydraulic cylinder. As described above, the annular buffer seal 22 may include a first axial pressure side formed with a plurality of adjacent axially facing pressure surfaces 220, 221, 222, and 223 facing the pressurized rod end chamber of the hydraulic cylinder 10, and an opposing second axial sealing side formed with a plurality of adjacent axially facing sealing surfaces 224, 225 facing the exterior of the hydraulic cylinder and configured to contact the support ring 24 in a mating, cooperative relationship within the annular groove 21. The buffer seal 22 also includes a radially outer circumferential surface 226 configured to contact the bottom of the annular groove 21, 351 along a portion or the entire outer circumferential surface, and a radially inner circumferential surface 227 configured to contact the piston rod 12 axially movable within the rod end 16 along a portion or the entire inner circumferential surface.

[0030] The two pressure surfaces on the axial pressure side of the buffer seal 22 may be axially tapered surfaces that converge to define an annular concave recess 23 on the axial pressure side of the annular buffer seal 22, the recess 23 separating the radially outer annular leg and the radially inner annular leg, and the distal end of the radially inner annular leg forming a lip that is configured to seal against the outer circumferential surface of the piston rod 12 when the piston rod is extended and retracted in the cylinder head. In an optional embodiment of the buffer seal, the pressure surface on the axial pressure side of the buffer seal 22 may form more than one concave annular recess along the radial extent of the buffer seal. Pressure from the rod end chamber of the hydraulic cylinder 10 may pass through the metal wear guides 360, 460 and enter the annular recess 23, or more than one recess defined in the axial pressure side of the buffer seal 22. The pressure may cause the radially outer annular leg of the buffer seal 22 to bend radially outward and press against the bottom surface of the annular groove 21, and cause the radially inner annular leg of the buffer seal 22 to bend radially inward and press against the piston rod 12.

[0031] The radially outer circumferential surface 226 of the buffer seal 22 can be configured to have a plurality of portions along its axial length that are located near or in contact with the bottom of the annular groove 21, leaving a small gap between some of these portions of the radially outer circumferential surface 226 and the bottom of the annular groove 21 when the pressure applied to the annular recess 23 drops below a certain threshold. Similarly, in various embodiments of the annular buffer seal 22 according to the present invention, the radially inner circumferential surface 227 of the buffer seal 22 is configured to have a portion that contacts the radially outer circumferential surface of the piston rod 12 along its axial length or its entire axial length. Portions of one or both of the radially outer circumferential surface 226 and the radially inner circumferential surface 227 of the buffer seal 22 can remain spaced apart from the bottom of the annular groove 21 and the piston rod 12 when the piston rod 12 moves axially to extend and retract relative to the rod end 316 and the hydraulic cylinder 10, depending on the amount of pressure applied to the annular recess 23 from the pressurized rod end chamber of the hydraulic cylinder 10. A higher pressure above a predetermined threshold that may be introduced into the annular recess 23 from the rod end chamber of the hydraulic cylinder 10 may cause one or both of the radially outer annular leg having the pressure surface 221 and the radially inner annular leg having the pressure surface 222 to bend, thereby creating a tighter seal between one or more portions of the annular buffer seal 22 and the annular groove 21 and / or the piston rod 12.

[0032] like Figure 2 As shown, and as described above, the buffer seal 22 can cooperatively cooperate with the support ring 24 along the axially facing sealing surfaces 224, 225, and the assembly of the buffer seal 22 and the support ring 24 can be cooperatively received in the annular groove 21 formed in the radial inner circumferential surface of the rod end 16, 316, 416 of the hydraulic cylinder 12. The axially facing annular sealing surface 224 can be disposed at a greater distance from the first axial pressure side of the annular buffer seal 22 than from the axially facing annular sealing surface 225, so that an annular recess is formed around the inner diameter of the annular buffer seal 22 on the axial sealing side of the annular buffer seal 22 at the location where the axially facing sealing surface 224 engages the axially facing sealing surface 225. Optional embodiments of the buffer seal and mating support ring can eliminate or change the size or configuration of the annular recess, wherein the entire radial extent of the axially facing sealing side of the buffer seal is substantially coplanar, curved, stepped or recessed, or otherwise configured with one or more annular steps or recesses. As shown in FIG. Figure 2 As shown in the exemplary embodiment of , the axially facing sealing surface 224 may be formed with a raised radius R1 at the entrance of the recess, and the raised radius R1 is predetermined to avoid generating a higher stress area at the entrance of the recess.

[0033] The entire arrangement of the buffer seal assembly and / or annular seal and wear guide disclosed above can be incorporated into the seal assembly of any hydraulic component. Therefore, the seals and the combination of seals and wear guides of the present invention have wide application in various machines including hydraulic actuators and / or hydraulic cylinders. Some advantages of the disclosed embodiments include providing a robust piston rod sealing system with multi-barrier contaminant control, higher resistance to the potentially harmful effects of temperature, humidity and pressure in the hydraulic actuator, optimized side loads on the components of the hydraulic cylinder incorporating the disclosed features, less machine downtime for servicing the hydraulic cylinder, longer life of the hydraulic cylinder components, including increased piston rod life, and extended oil life of the hydraulic cylinder due to avoiding contaminant penetration into the hydraulic cylinder or hydraulic fluid leakage from the hydraulic cylinder.

[0034] It will be apparent to those skilled in the art that various modifications and variations may be made to the disclosed individual seals, seal assemblies, and seal arrangements without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art in view of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered exemplary only, with the true scope and spirit of the invention being indicated by the appended claims and their equivalents.

Claims

1. A sealing assembly for a hydraulic cylinder piston rod (12) of a hydraulic cylinder (10), include: The annular buffer seal (22) comprises: a first axial pressure side configured to face the rod end chamber of the hydraulic cylinder (10) and to fit adjacent to a first axial side surface of an annular groove (21) defined in the rod end of the hydraulic cylinder (10) through which the piston rod (12) passes, and a second axial sealing side, opposite the first axial pressure side, the second axial sealing side including a radially outer annular sealing surface (224) and a radially inner annular sealing surface (225), wherein the radially outer annular sealing surface (224) is spaced further from the first axial pressure side of the annular buffer seal (22) than the radially inner annular sealing surface (225) of the buffer seal (22), such that an annular recess is formed on the second axial sealing side of the annular buffer seal around the inner diameter of the annular buffer seal; and The annular support ring (24) comprises: a radially extending leg portion (26) configured to extend along substantially the entire radial extent of the radially outer annular sealing surface (224) of the annular buffer seal (22), and An axially extending leg (28) is adjacent to the radially extending leg (26) and is configured to extend axially into an annular recess formed around the inner diameter of the annular buffer seal (22) on a second axial sealing side of the annular buffer seal.

2. A sealing assembly according to claim 1, wherein the first axial pressure side of the annular buffer seal (22) includes a radially outer annular pressure surface (220), and the radially outer annular pressure surface (220) is connected to a radially inner annular pressure surface (223) by two continuous and converging conical pressure surfaces (221, 222), and the two continuous and converging conical pressure surfaces (221, 222) together define an annular recessed recess (23) in the first axial pressure side of the buffer seal (22).

3. The sealing assembly according to claim 1, wherein the radially extending leg (26) of the support ring (24) terminates in a chamfered outer circumferential surface (247) at the radial outer edge of the support ring (24) on the side facing away from the buffer seal (22).

4. The sealing assembly according to claim 1, wherein the annular buffer seal (22) further includes a radially outer circumferential surface (226) configured to contact the bottom of the annular groove (21) and a radially inner circumferential surface (227) configured to contact the piston rod (12).

5. A sealing assembly according to claim 4, wherein the radial outer circumferential surface (226) of the annular buffer seal (22) is configured with a portion along its axial length, which is located near the bottom of the annular groove (21) or in contact with the bottom of the annular groove (21), and when the pressure applied to the first axial pressure side of the buffer seal (22) drops below a predetermined threshold, a small gap is left between some portions of the radial outer circumferential surface and the bottom of the annular groove (21).

6. The seal assembly of claim 2, wherein the annular concave recess (23) is defined between a radially outer annular leg of the buffer seal (22) and a radially inner annular leg of the buffer seal (22).

7. A sealing assembly according to claim 6, wherein the pressure applied to the annular recessed depression (23) causes the radially outer annular leg to bend radially outward and press against the bottom surface of the annular groove (21), and causes the radially inner annular leg to bend radially inward and press against the piston rod (12).

8. A sealing assembly according to claim 1, wherein the intersection between the radially extending leg (26) of the support ring (24) and the axially extending leg (28) of the support ring (24) includes a fillet chamfer (242), and the fillet chamfer (242) cooperates with a matching fillet chamfer at the intersection of the radially outer annular sealing surface (224) of the buffer seal (22) and the radially inner annular sealing surface (225) of the buffer seal (22) at the entrance to the annular recess.

9. The sealing assembly according to claim 8, wherein the radius of each mating fillet chamfer on the support ring (24) and the buffer seal (22) is equal to half or more of the thickness of adjacent portions of the support ring and the buffer seal, respectively.

10. A hydraulic cylinder (10), include: Cylinder (14); a cylinder head at the rod end (16) of the cylinder (14); a piston rod (12) extending through the cylinder head at a rod end (16) of the barrel (14) and configured for axial movement relative to the cylinder head; as well as a plurality of seals (18) disposed in axially spaced annular grooves formed around the inner circumferential surface of the rod end (16) of the barrel (14) and configured for sealing engagement with the piston rod (12), wherein one of the plurality of seals is a buffer seal assembly, the buffer seal assembly comprising: The annular buffer seal (22) comprises: a first axial pressure side configured to face the rod end chamber of the hydraulic cylinder (10) and to fit adjacent to a first axial side surface of an annular groove (21) defined in the rod end of the barrel (14) through which the piston rod (12) passes, and a second axial sealing side opposite the first axial pressure side, the second axial sealing side including a radially outer annular sealing surface (224) and a radially inner annular sealing surface (225), wherein the radially outer annular sealing surface (224) is spaced further from the first axial pressure side of the annular buffer seal than the radially inner annular sealing surface (225) of the buffer seal, such that an annular recess is formed on the second axial sealing side of the annular buffer seal around an inner diameter of the annular buffer seal; and The annular support ring (24) comprises: a radially extending leg portion (26) configured to extend along substantially the entire radial extent of the radially outer annular sealing surface (224) of the annular buffer seal (22), and An axially extending leg (28) is adjacent to the radially extending leg (26) and is configured to extend axially into an annular recess formed around an inner diameter of the annular buffer seal on a second axial sealing side of the annular buffer seal.

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