buffer stop

Abstract

A buffer stop is provided between the flange and the protrusion. The flange has a first annular surface extending from an outer peripheral surface of a shaft movable in an axial direction, and the protrusion has a second annular surface spaced apart from and facing the first annular surface and extending toward the shaft from an inner peripheral surface of the housing. The buffer stop includes a metal ring in contact with the first annular surface, an annular buffer base provided between the metal ring and the second annular surface and joined to the metal ring, and an annular member provided between the buffer base and the second annular surface and joined to the buffer base. The buffer base contains a rubber elastic material. The metal ring is an annular flat plate. The annular member is spaced apart from the metal ring and provided radially inside the buffer base. The annular member has a rigidity greater than a rigidity of the buffer base.

Description

Technical Field

[0001] This disclosure relates to buffer stop blocks. Background Technology

[0002] For example, a steering system is used in a car. The steering system includes a steering wheel operated by the driver, a steering shaft connected to the steering wheel, a pinion coaxial with the steering shaft, and a rack and pinion comprising a rack that converts the rotation of the pinion into axial motion. The motion of the shaft is transmitted to the corresponding wheel via a tie rod. When the rack moves, the tie rod oscillates, causing the corresponding wheel to turn. The rack and pinion are housed in a rack housing.

[0003] The steering mechanism includes a buffer stop that reduces the impact between the rack rod and the rack housing caused by the swing of the tie rod. Such a buffer stop is disclosed in Patent Document 1.

[0004] Figure 6 This is a view showing a standard buffer stop block 9. Figure 6 Also shown are rack rod 81, rack housing 82 and tie rod 83. Figure 6 The buffer stop block 9 shown includes an L-shaped metal ring 91 that contacts the rack rod 81, and a rubber elastomer 93 disposed between the L-shaped metal ring 91 and the rack housing 82. The L-shaped metal ring 91 improves durability under high loads.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2016-136031. Summary of the Invention

[0006] The problem to be solved by the present invention The L-shaped metal ring 91 comprises two parts: a portion extending along the central axis A of the rack 81, and a radially extending portion. Therefore, the L-shaped metal ring 91 occupies a considerable area of ​​the buffer stop block 9, resulting in high manufacturing costs.

[0007] Figure 7 Another conventional buffer stop 7 is shown, designed to reduce manufacturing costs. Figure 7 The buffer stop block 7 shown includes a flat metal ring 71. A rubber elastomer 72 is disposed between the metal ring 71 and the rack housing 82. Because the metal ring 71 is formed flat, manufacturing costs can be reduced.

[0008] In the prior art buffer stop 7, the reduction of impact between the rack rod 81 and the rack housing 82 is mainly achieved by the rubber elastomer 72. In this configuration, if the grease applied to the rack rod 81 enters the interface between the rack housing 82 and the rubber elastomer 72, the coefficient of friction at the contact surface between the rack housing 82 and the rubber elastomer 72 decreases. Therefore, the rubber elastomer 72 becomes more easily deformable, and the amount of deflection increases undesirably. This easily reduces the durability of the buffer stop 7.

[0009] Therefore, there is a need for a buffer stop that improves durability at a lower cost compared to existing technologies.

[0010] Problem Solving To address the aforementioned problems, a buffer stop block according to one aspect of the invention is disposed between a flange and a protrusion, wherein the flange has a first annular surface extending from the outer peripheral surface of a shaft capable of axial movement, and the protrusion has a second annular surface spaced apart from and facing the first annular surface, extending from the inner peripheral surface of the housing toward the shaft. The buffer stop block comprises: a metal ring contacting the first annular surface; an annular buffer base disposed between and engaged with the metal ring and the second annular surface; and an annular member disposed between and engaged with the buffer base. The buffer base comprises a rubber-elastic material. The metal ring is an annular plate. The annular member is spaced apart from the metal ring and disposed radially inside the buffer base. The stiffness of the annular member is greater than the stiffness of the buffer base.

[0011] Invention Effects Compared with existing technologies, this disclosure enables improved cushioning performance and durability at a low cost. Attached Figure Description

[0012] Figure 1 This is a cross-sectional view showing a portion of a steering device including a buffer stop block according to one embodiment.

[0013] Figure 2 This is a cross-sectional view showing a portion of the buffer stop block according to this embodiment.

[0014] Figure 3 This is an enlarged cross-sectional view of a portion of the buffer stop block according to this embodiment.

[0015] Figure 4 This is a characteristic diagram of the buffer stop block according to this embodiment.

[0016] Figure 5 It is a cross-sectional view based on the modified buffer stop block.

[0017] Figure 6 This is a view showing a standard buffer stop block.

[0018] Figure 7 This illustrates another conventional buffer stop block designed to reduce manufacturing costs. Detailed Implementation

[0019] Preferred embodiments of the present disclosure will now be described with reference to the accompanying drawings. In the drawings, dimensions or scales may be appropriately altered for clarity. Unless otherwise specified, the scope of this disclosure is not limited to the embodiments described below.

[0020] 1. Steering mechanism In one example, a rack and pinion steering system is used in a vehicle such as an automobile. The steering system includes a steering wheel operated by the driver, a steering shaft coupled to the steering wheel, a pinion coaxial with the steering shaft, and a shaft comprising a rack that converts the rotation of the pinion into axial motion. The axial motion of the shaft is transmitted to the wheels via a tie rod. When the shaft moves, the tie rod oscillates relative to the shaft, thereby steering the corresponding wheel. The shaft is housed in a housing.

[0021] This steering system includes a shock absorber that reduces the impact between the shaft and the housing caused by the swing of the tie rod.

[0022] Figure 1 This is a cross-sectional view showing a portion of a steering device 100 including a buffer stop block 1 according to an embodiment. Specifically, the steering device 100 includes a shaft 3, a tie rod 4, a housing 5, a rack cover 6, and a shock absorber 10. The shock absorber 10 includes a flange 30, a protrusion 50, and the buffer stop block 1. The flange 30 is connected to the shaft 3, and the protrusion 50 is connected to the housing 5. The flange 30 can be considered as part of the shaft 3, and the protrusion 50 can be considered as part of the housing 5.

[0023] In one example, shaft 3 is cylindrical and includes a rack 35 extending in the axial direction. As used herein, the term "axial direction" refers to the direction along the central axis A of shaft 3 and corresponds to the longitudinal direction of shaft 3. Rack 35 meshes with a pinion (not shown) to convert the rotational motion of the pinion into linear motion along the central axis A. Shaft 3 can move axially and is typically made of metal.

[0024] The housing 5 is a cylindrical component that houses the shaft 3 and is fixed to the vehicle body (not shown). In one example, the cylindrical housing 5 extends axially, and the inner diameter of the housing 5 is slightly larger than the outer diameter of the shaft 3. The housing 5 may be made of metal.

[0025] The flange 30 of the damping device 10 is a stud end attached to the end of the shaft 3. The flange 30 may be made of metal and includes a flange base 301 and a protruding portion 302.

[0026] In one example, the flange base 301 is cylindrical and has an outer diameter larger than that of the shaft 3. The flange base 301 defines an opening 301D. The opening 301D is a flat-bottomed hole leading to the side of the flange base 301 opposite to the protrusion 302. The ball joint 40 of the pull rod 4 is received in the opening 301D via a cushioning material 401. When the rack 35 moves along the central axis A, the pull rod 4 oscillates about the central axis A.

[0027] The flange base 301 has a first annular surface 30s extending radially outward from the outer peripheral surface 3s of the shaft 3. As used herein, the term "radially outward" refers to a direction orthogonal to and away from the central axis A of the shaft 3.

[0028] In the following text, the term "radial inward" refers to a direction orthogonal to the central axis A of shaft 3 and toward the central axis A, away from housing 5. Furthermore, the term "radial direction" refers to a direction orthogonal to the central axis A of shaft 3.

[0029] The protrusion 302 protrudes from the flange base 301 toward the shaft 3 and is integrally formed with the flange base 301. In one example, the protrusion 302 is cylindrical. A recess 3D is provided at the end of the shaft 3, and the protrusion 302 is disposed in the recess 3D. In one example, one of the inner circumferential surface of the recess 3D or the outer circumferential surface of the protrusion 302 is provided with an internal thread, and the other is provided with an external thread. The protrusion 302 and the recess 3D are connected together by threads to connect the flange 30 to the shaft 3.

[0030] The protrusion 50 of the damping device 10 is an annular structure that extends radially inward from the inner peripheral surface 5s of the housing 5 and is integrally formed with the housing 5. The protrusion 50 surrounds the outer peripheral surface 3s of the shaft 3. In one example, the protrusion 50 is annular and has an inner diameter slightly larger than the outer diameter of the shaft 3. The protrusion 50 is spaced apart from the flange base 301.

[0031] The protrusion 50 has a second annular surface 50s. The second annular surface 50s is the end face of the protrusion 50 closer to the flange 30. The second annular surface 50s extends radially inward from the inner circumferential surface of the housing 5. The second annular surface 50s is spaced apart from the first annular surface 30s and faces the first annular surface 30s.

[0032] The housing 5 includes a receiving portion 50H. The receiving portion 50H defines a space defined by a portion extending from the protrusion 50 toward the ball joint 40 by the second annular surface 50s and the inner circumferential surface 5s of the housing 5. A flange base 301 is received in the receiving portion 50H. The inner diameter of the wall defining the receiving portion 50H is larger than the outer diameter of the flange base 301. A rack cover 6 is connected to the housing 5. The rack cover 6 includes a cylindrical bellows and receives a pull rod 4.

[0033] The damping device 10 has a buffer stop 1 disposed between the flange 30 and the protrusion 50. Specifically, the buffer stop 1 is disposed between the first annular surface 30s of the flange 30 and the second annular surface 50s of the protrusion 50. The buffer stop 1 reduces the impact between the shaft 3 and the housing 5 caused by the swing of the tie rod 4.

[0034] 2. Buffer stop block Figure 2 This is a cross-sectional view showing a portion of the buffer stop block 1 according to this embodiment. Figure 2 As shown, the buffer stop block 1 includes a metal ring 11, a buffer base 12, and an annular component 13.

[0035] The metal ring 11 is an annular plate. In this embodiment, the metal ring 11 is flat.

[0036] In one example, the metal ring 11 may be made of metal, such as hot-rolled low-carbon steel sheet (e.g., SPHC).

[0037] In one example, the buffer base 12 can be connected to the metal ring 11 by bonding (e.g., by vulcanization). In this embodiment, the buffer base 12 is tubular and substantially cylindrical. The axial length of the buffer base 12 is greater than the axial thickness of the metal ring 11. The buffer base 12 is elastic and absorbs impact. The stiffness of the buffer base 12 is less than the stiffness of the metal ring 11. The buffer base 12 is formed of a rubber-elastic material. The term "rubber-elastic material" includes thermosetting elastomer rubber, synthetic resins having rubber elasticity, and rubber-containing blends. From the viewpoint of high hardness and improved durability, the buffer base 12 is preferably made of nitrile butadiene rubber (NBR), more preferably of NBR compounded with carbon black.

[0038] The buffer base 12 has an outer diameter (OD) and an inner diameter (ID). The difference between OD and ID (hereinafter referred to as the "OD-ID difference") is slightly smaller than the OD-ID difference of the metal ring 11, but may also be equal to it. As used herein, the term "OD-ID difference" refers to the radial length. Furthermore, the volume of the buffer base 12 in the buffer stop block 1 is larger than the volume of the metal ring 11 in the buffer stop block 1.

[0039] The buffer base 12 includes a cover portion 121 that covers the outer peripheral surface 111 of the metal ring 11. The inner peripheral surface 112 of the metal ring 11 is not covered by the buffer base 12.

[0040] In one example, the annular member 13 may be joined to the buffer base 12 using vulcanization. In this embodiment, the annular member 13 is annular. The annular member 13 is disposed on the surface of the buffer base 12 opposite to the metal ring 11. The annular member 13 is spaced apart from the metal ring 11. In other words, the buffer base 12 includes a portion located between the annular member 13 and the metal ring 11. The annular member 13 is disposed radially inward of the buffer base 12.

[0041] The volume of the annular member 13 in the buffer stop block 1 is smaller than the volume of the buffer base 12 in the buffer stop block 1, and also smaller than the volume of the metal ring 11 in the buffer stop block 1. Furthermore, the OD-ID difference of the buffer base 12 is smaller than the OD-ID difference of the buffer base 12. In addition, in this embodiment, the OD-ID difference of the annular member 13 increases in the direction away from the metal ring 11.

[0042] The stiffness of the annular member 13 is greater than that of the buffer base 12. In one example, the Young's modulus of the annular member 13 may be greater than that of the Young's modulus of the buffer base 12. The annular member 13 may be formed of a resin or rubber elastic material.

[0043] The Young's modulus of the annular component 13 can be in the range of 100 MPa to 1000 MPa, but is not limited thereto. In one example, the Young's modulus of the buffer substrate 12 can be 1 kgf / cm². 2 Up to 100 kgf / cm 2 The range is, but not limited to, that of the metal ring 11. The Young's modulus can be in the range of 10 GPa to 500 GPa, but is not limited to this.

[0044] Figure 3 This is an enlarged cross-sectional view of a portion of the buffer stop block 1 according to this embodiment. Figure 3 As shown, the buffer stop block 1 is disposed between the first annular surface 30s and the second annular surface 50s, and contacts both the first annular surface 30s and the second annular surface 50s. In one example, the buffer stop block 1 can be pressed into place between the first annular surface 30s and the second annular surface 50s, causing the buffer base 12 to elastically deform. Figure 3 In the example shown, the buffer stop 1 does not contact either the shaft 3 or the housing 5; however, the buffer stop 1 may contact the shaft 3.

[0045] The metal ring 11 of the buffer stop block 1 contacts the first annular surface for 30 seconds. The buffer base 12 and the annular member 13 respectively contact the second annular surface for 50 seconds. Specifically, the end face 125 of the buffer base 12 opposite to the metal ring 11 and the end face 135 of the annular member 13 opposite to the metal ring 11 respectively contact the second annular surface for 50 seconds. Figure 2 As shown, when the buffer stop block 1 is not installed between the first annular surface 30s and the second annular surface 50s (i.e., in the uninstalled state), the end face 125 and the end face 135 are continuous, without any steps and flush with each other.

[0046] The buffer stop block 1 is subjected to impact transmitted via the metal ring 11 under the swing of the pull rod 4, thereby compressing and elastically deforming the buffer base 12. When the flange 30 moves toward the protrusion 50, the gap between the first annular surface 30s and the second annular surface 50s decreases, and the buffer base 12 is compressed in the axial direction and expands radially inward and radially outward. Therefore, the buffer stop block 1 is compressed between the first annular surface 30s and the second annular surface 50s. Thus, the buffer stop block 1 mainly absorbs the impact of the buffer base 12.

[0047] The buffer stop block 1 includes a metal ring 11, a buffer base 12, and an annular member 13. The metal ring 11 contacts a first annular surface 30s and is an annular plate. The buffer base 12 contains a rubber elastic material, is disposed between the first annular surface 30s and the second annular surface 50s, and is connected to the metal ring 11. The annular member 13 contains a rubber elastic material, is disposed between the first annular surface 30s and the second annular surface 50s, and is connected to the buffer base 12.

[0048] By including the metal ring 11, the buffer stop block 1 is able to absorb loads that the buffer base 12 alone cannot absorb. The metal ring 11 is formed as a flat plate, and therefore can be manufactured as a single sheet, thereby reducing the volume of the metal ring 11 in the buffer stop block 1 compared to existing technologies. This also reduces manufacturing costs compared to existing technologies.

[0049] The stiffness of the annular member 13 is greater than that of the buffer base 12. Therefore, the contact pressure of the annular member 13 relative to the second annular surface 50s is greater than the contact pressure of the buffer base 12 relative to the second annular surface 50s. The annular member 13, located radially inward of the buffer base 12, acts as a sealing member, preventing grease from entering the interface between the buffer base 12 and the second annular surface 50s. Therefore, the annular member 13 prevents the grease coated on the shaft 3 from moving radially outwards and entering the interface between the buffer base 12 and the second annular surface 50s. This improves the durability of the buffer base 12.

[0050] Without the annular member 13, grease can easily enter the interface between the buffer base 12 and the second annular surface 50s. Therefore, the coefficient of friction at the interface between the end face 125 of the buffer base 12 and the second annular surface 50s decreases. The decrease in friction makes the buffer base 12 more prone to deformation, leading to excessive deflection and thus compromising the durability of the buffer stop block 1.

[0051] Conversely, in this embodiment, by providing the annular member 13, grease ingress into the interface between the buffer base 12 and the second annular surface 50s can be suppressed. Therefore, a decrease in the coefficient of friction is impossible. Consequently, deformation and excessive deflection of the buffer base 12 are suppressed, and the durability of the buffer stop block 1 can be improved.

[0052] The annular member 13 is spaced apart from the metal ring 11. Therefore, even if the first annular surface 30s and the second annular surface 50s move toward each other and the buffer base 12 is axially compressed, the annular member 13 is unlikely to be trapped between the metal ring 11 and the second annular surface 50s and damaged. If the annular member 13 is connected to the metal ring 11, axial compression of the buffer base 12 may cause the annular member 13 to be squeezed and broken between the metal ring 11 and the second annular surface 50s. In addition, because the annular member 13 is spaced apart from the metal ring 11, axial compression of the buffer base 12 more readily allows for elastic deformation of the buffer base 12 in the radial direction.

[0053] As described above, the annular member 13 is disposed radially inside the buffer base 12. In this configuration, the buffer base 12 contacts the second annular surface 50s. Therefore, compared to the case where the annular member 13 covers the end face 125 of the buffer base 12 and the buffer base 12 does not contact the second annular surface 50s, the cushioning provided by the buffer base 12 is improved.

[0054] Figure 4 This is a characteristic diagram of the buffer stop block 1 according to this embodiment. For example... Figure 4 As shown, the horizontal axis represents the displacement of the buffer stop block 1 [mm], and the vertical axis represents the load applied to the buffer stop block 1 [kN]. The displacement of the buffer stop block 1 corresponds to the axial compressive strain of the buffer base 12.

[0055] Characteristic curve (solid line) L1 represents the buffer stop block 1 in this embodiment. Characteristic curve (dashed line) L2 represents the buffer stop block 1 in this embodiment. Figure 7 The buffer stop block 7 of the comparative example is shown. The buffer stop block 1 according to this embodiment includes an annular member 13, while the buffer stop block 7 according to the comparative example does not include an annular member 13. The volume of the buffer stop block 1 of this embodiment is the same as the volume of the buffer stop block 7 of the comparative example.

[0056] The slope of characteristic curve L1 is greater than that of characteristic curve L2 in the comparative example. Therefore, the linear region of characteristic curve L1 (i.e., the region below curve L1) is larger than the linear region of characteristic curve L2 (i.e., the region below curve L2). Therefore, compared to the comparative example, the buffer stop block 1 according to this embodiment absorbs more energy and exhibits a larger maximum compressive displacement. In this embodiment, the increased energy absorption reduces deflection during impact, thereby improving buffering performance and durability compared to the comparative example. These improvements are achieved without increasing the volume of the buffer stop block 1.

[0057] When grease is present between the buffer base 12 and the second annular surface 50s, the coefficient of friction at the end face 125 of the buffer base 12 is easily reduced. Reduced friction easily leads to an increase in internal stress within the buffer base 12, thereby reducing the buffer base's ability to absorb energy. Therefore, the amount of energy that can be absorbed by the buffer base 12 is easily reduced, resulting in deterioration of buffering performance. The buffer stop block 1 in this embodiment suppresses the reduction in buffering performance.

[0058] The aforementioned annular member 13 can be made of metal or resin, but preferably contains resin. By forming the annular member 13 from resin, it is possible to easily mold the annular member 13 into various shapes.

[0059] There are no particular restrictions on the materials used for the resin in forming the annular member 13. However, super engineering plastics such as polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK) are preferred because of their excellent durability and impact resistance. Using such materials, grease ingress between the buffer base 12 and the second annular surface 50s can be more effectively prevented compared to using other materials.

[0060] Preferably, the material of the annular member 13 has grease resistance. Super engineering plastics (such as PTFE and PEEK) have good grease resistance.

[0061] Preferably, the volume of the annular member 13 is smaller than the volume of the buffer base 12. If the volume of the annular member 13 is larger than the volume of the buffer base 12, the buffering performance of the buffer stop block 1 is more likely to deteriorate compared to the case where the volume of the annular member 13 is smaller. Since the volume of the annular member 13 is smaller than the volume of the buffer base 12, the buffering performance of the buffer stop block 1 is improved compared to the case where the volume of the annular member 13 is larger than the volume of the buffer base 12.

[0062] like Figure 2As shown, when no load is applied to the buffer stop block 1, the end face 125 of the buffer base 12 opposite to the metal ring 11 and the end face 135 of the annular member 13 opposite to the metal ring 11 are flush with each other. Therefore, compared to the case where there is a step between the end face 125 and the end face 135, it is easier to achieve uniform contact pressure between the end face 135 and the second annular surface 50s over the entire area of ​​the end face 135. This improved uniformity improves the sealing performance of the annular member 13, thereby more effectively preventing grease from entering between the buffer base 12 and the second annular surface 50s.

[0063] like Figure 2 and Figure 3 As shown, the engagement surface 130 of the annular member 13, which engages with the buffer base 12, is inclined relative to the axial direction. The OD-ID difference of the annular member 13 increases in the direction away from the metal ring 11. Therefore, the cross-sectional shape of the annular member 13 is triangular.

[0064] Figure 5 This is a cross-sectional view based on the modified buffer stop block 1A. Figure 5 In the buffer stop block 1A shown, the OD-ID difference of the annular member 13A remains constant in the axial direction. Therefore, the cross-sectional shape of the annular member 13A is quadrilateral. The annular member 13A provides a similar effect to the annular member 13 described above.

[0065] and Figure 5 Compared to the annular member 13A shown, Figure 3 The annular member 13 shown exerts a higher contact pressure on the second annular surface 50s. Figure 3 In the annular member 13 shown, as the first annular surface 30s and the second annular surface 50s move toward each other, the force acting on the buffer base 12 is transmitted to the mating surface 130. The approach of the first annular surface 30s and the second annular surface 50s toward each other allows the distal portion 139 of the annular member 13 to exert a greater force on the second annular surface 50s. Therefore, the sealing performance provided by the annular member 13 is improved. Thus, grease ingress between the buffer base 12 and the second annular surface 50s is particularly effectively prevented. Therefore, the buffer stop 1 provides improved durability and cushioning performance.

[0066] Ring member 13 is not limited to Figure 3 and Figure 5 The cross-sectional shape is shown. The mating surface 130 may be curved.

[0067] As described above, the buffer base 12 includes a cover portion 121 that covers the outer peripheral surface 111 of the metal ring 11. Even if the pull rod 4 swings and causes the buffer stop block 1 to contact the housing 5, the cover portion 121 prevents the metal ring 11 from contacting the housing 5. Therefore, unwanted noise caused by contact between the metal housing 5 and the metal ring 11 is prevented.

[0068] 2. Modification The aforementioned embodiments can be modified in various ways. The shock absorption device 10, including the buffer stop block 1 or 1A, can be applied not only to vehicles, but also to transportation equipment and industrial equipment.

[0069] Although this disclosure has been described with reference to preferred embodiments, it is not limited thereto. Components of this disclosure may be replaced by components having similar functions to those in the foregoing embodiments, and additional components may be incorporated.

[0070] 3. Appendix Based on the above embodiments or modifications, the following aspects can be understood.

[0071] A preferred example of aspect 1 of this disclosure is a buffer stop disposed between a flange and a protrusion, wherein the flange has a first annular surface extending from the outer peripheral surface of a shaft movable in an axial direction, and the protrusion has a second annular surface spaced apart from and facing the first annular surface, extending from the inner peripheral surface of the housing toward the shaft. The buffer stop comprises: a metal ring contacting the first annular surface; an annular buffer base disposed between and engaged with the metal ring and the second annular surface; and an annular member disposed between and engaged with the buffer base. The buffer base comprises a rubber-elastic material. The metal ring is an annular plate. The annular member is spaced apart from the metal ring and disposed radially inside the buffer base. The stiffness of the annular member is greater than the stiffness of the buffer base.

[0072] According to aspect 1, the metal ring becomes a flat plate, thus enabling it to be manufactured as a single sheet at a lower cost compared to existing technologies.

[0073] The annular member is located radially inside the buffer base, and its stiffness is greater than that of the buffer base. This design prevents grease from entering the interface between the buffer base and the second annular surface, thus improving the durability of the buffer base.

[0074] The annular component is spaced apart from the metal ring. Even when the buffer base is compressed, the annular component is not easily damaged. Therefore, according to aspect 1, it is possible to improve cushioning performance and durability at a low cost.

[0075] In aspect 2, which is a preferred example of aspect 1, the annular member comprises resin.

[0076] Therefore, it is possible to easily mold ring-shaped components into various shapes and provide cushioning stops with excellent durability.

[0077] In aspect 3, which is a preferred example of aspect 1, the volume of the annular member is smaller than the volume of the buffer base.

[0078] It can reduce the reduction in the buffering performance of the buffer stop block caused by the reduced occupancy of the buffer base due to the setting of the ring component.

[0079] In aspect 4, which is a preferred example of aspect 1, the buffer base also includes a covering portion that covers the outer peripheral surface of the metal ring.

[0080] The cover design prevents the metal ring from contacting the housing and also prevents unwanted noise from being generated.

[0081] In aspect 5, which is a preferred example of aspect 1, the end face of the buffer base located at the end opposite to the metal ring is flush with the end face of the annular member located at the end opposite to the metal ring.

[0082] Therefore, it is easier to achieve uniform contact pressure between the annular component and the second annular surface. This improves the suppression of grease ingress between the buffer base and the second annular surface.

[0083] In aspect 6, which is a preferred example of aspect 1, the engagement surface of the annular member to the buffer base is inclined relative to the axial direction. The difference between the outer diameter and the inner diameter of the annular member increases in the direction away from the metal ring.

[0084] In aspect 6, the distal portion of the annular member is able to apply a greater force to the second annular surface. Therefore, this significantly improves the inhibition of grease ingress between the buffer base and the second annular surface.

[0085] Explanation of reference numerals in the attached figures 1... Buffer stop block, 1A... Buffer stop block, 2... Buffer stop block, 3... Shaft, 3s... Outer peripheral surface, 4... Tie rod, 5... Housing, 5s... Inner peripheral surface, 6... Rack cover, 7... Buffer stop block, 9... Buffer stop block, 10... Shock absorption device, 11... Metal ring, 12... Buffer base, 13... Annular component, 13A... Annular component, 30... Flange, 30s... First annular surface, 35... Rack, 40... Ball joint, 50... Protrusion, 50H... Receiving part, 50s... Second annular surface, 71 ...metal ring, 72...rubber elastomer, 81...rack rod, 82...rack housing, 83...pull rod, 91...L-shaped metal ring, 93...rubber elastomer, 100...steering device, 111...outer peripheral surface, 112...inner peripheral surface, 121...covering portion, 125...end face, 130...jointing surface, 135...end face, 139...fart portion, 301...flange base, 301D...opening, 302...protrusion, 401...buffer material, A...central axis, L1...characteristic curve, L2...characteristic curve.

Claims

1. A buffer stop block disposed between a flange and a protrusion, the flange having a first annular surface extending from an outer peripheral surface of a shaft movable in an axial direction, the protrusion having a second annular surface spaced apart from and facing the first annular surface, and extending from an inner peripheral surface of a housing toward the shaft, the buffer stop block comprising: A metal ring, wherein the metal ring is in contact with the first annular surface; An annular buffer base, the buffer base being disposed between the metal ring and the second annular surface and engaged to the metal ring; An annular member is disposed between the buffer base and the second annular surface and is engaged with the buffer base. The buffer base comprises a rubber elastic material. The metal ring is a ring-shaped plate. The annular member is spaced apart from the metal ring and disposed radially inside the buffer base. The stiffness of the annular component is greater than the stiffness of the buffer base.

2. The buffer stop block according to claim 1, in, The annular component contains resin.

3. The buffer stop block according to claim 1, in, The volume of the annular component is smaller than the volume of the buffer base.

4. The buffer stop block according to claim 1, in, The buffer base also includes a covering portion that covers the outer peripheral surface of the metal ring.

5. The buffer stop block according to claim 1, in, The end face of the buffer base located at the end opposite to the metal ring is flush with the end face of the annular member located at the end opposite to the metal ring.

6. The buffer stop block according to claim 1, in, The engagement surface of the annular member to the buffer base is inclined relative to the axial direction, and The difference between the outer diameter and the inner diameter of the annular component increases in the direction away from the metal ring.

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