sliding bushing

Abstract

This invention provides a novel sliding bushing structure that advantageously allows for setting both a stiffer elastic characteristic in the axial right-angle direction and a softer elastic characteristic in the torsional and lateral directions. The invention comprises a sliding bushing 10 connecting an inner shaft member 12 and an outer cylinder member 14 via a main rubber elastomer 16, allowing the inner shaft member 12 to slide relative to the main rubber elastomer 16. The inner shaft member 12 has a large-diameter protrusion 18 midway along the axial direction, and the outer cylinder member 14 has a tapered portion 28 with a smaller diameter extending outward from both axial ends. The outer peripheral surface of the protrusion 18 in the inner shaft member 12 has a non-adhesive portion 32 that is not bonded to the main rubber elastomer 16 but allows sliding relative to it. Furthermore, the outer peripheral surface of the inner shaft member 12, located axially outward from the non-adhesive portion 32, has an adhesive portion 30 to which the main rubber elastomer 16 is vulcanized and bonded.

Description

Technical Field

[0001] The present invention relates to bushings such as suspension bushings for automobiles, and more particularly to sliding bushings that allow sliding of an inner shaft member relative to a main rubber elastomer. Background Technology

[0002] Previously, bushings for automobile suspension bushings, such as those disclosed in Japanese Patent Application Publication No. 2010-159860 (Patent Document 1), were known. The bushing in Patent Document 1 has a structure in which the shaft member and the outer cylinder are connected by a rubber-like elastomer.

[0003] In addition, when both high elasticity in the right-angle direction and low elasticity in the torsional direction are desired, as in suspension bushings, a structure can be adopted as shown in Patent Document 1, in which a first bulge is provided on the shaft member and a second bulge is provided on the outer cylinder, thereby arranging the first and second bulges concentrically.

[0004] However, in suspension bushings and the like, there is sometimes a need for low elasticity characteristics relative to torsional input. In this case, by configuring the shaft member to be non-adhesive relative to the rubber-like elastomer, thereby allowing relative rotation between the shaft member and the outer cylinder, the required low elasticity characteristics in the torsional direction can be achieved.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2010-159860 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, the inventors of this invention have discovered through investigation that, in the structure of Patent Document 1, if the shaft member is simply not bonded to the rubber-like elastomer and torsional displacement (rotation) is allowed, the rubber-like elastomer compressed between the first bulge and the outer cylinder is prone to deforming axially outward. Due to this outward retraction of the rubber-like elastomer, it is difficult to set a high elasticity in the axial right-angle direction. Furthermore, it has been clarified that a new problem exists where a harder characteristic is desired in the axial right-angle direction, which may not satisfy the required characteristics.

[0010] The problem to be solved by the present invention is to provide a novel sliding bushing with a structure that can advantageously set both a stiffer elastic characteristic in the right-angle direction of the shaft and a softer elastic characteristic in the torsional and lateral directions.

[0011] means for solving problems

[0012] Hereinafter, preferred embodiments for understanding the present invention will be described. However, the embodiments described below are illustrative and can be appropriately combined with each other. Furthermore, the multiple constituent elements described in each embodiment can be understood and used as independently as possible, and can also be appropriately combined with any constituent element described in other embodiments. Therefore, the present invention is not limited to the embodiments described below, and various other embodiments can be implemented.

[0013] The first type is a sliding bushing having an inner shaft member and an outer cylinder member connected by a main rubber elastomer and allowing the inner shaft member to slide relative to the main rubber elastomer. The inner shaft member has a protrusion with a large diameter at the midpoint of the axial direction, and the outer cylinder member has a tapered portion with a small diameter extending from both ends of the axial direction outward. The outer peripheral surface of the protrusion in the inner shaft member has a non-adhesive portion that is not bonded to the main rubber elastomer but allows sliding relative to the main rubber elastomer. The outer peripheral surface of the inner shaft member that is axially outer of the non-adhesive portion has an adhesive portion to which the main rubber elastomer is vulcanized and bonded.

[0014] According to the sliding bushing configured in this manner, the outer peripheral surface of the protrusion of the inner shaft member has a non-adhesive portion where the main body rubber elastomer is set as non-adhesive. By providing the non-adhesive portion on the outer peripheral surface of the protrusion, sliding between the inner shaft member and the main body rubber elastomer is allowed in the protrusion, thereby achieving low elasticity in the torsional and lateral directions.

[0015] Furthermore, an adhesive portion for bonding the main rubber elastomer is provided axially outside the non-adhesive portion on the outer peripheral surface of the inner shaft member. Because the adhesive portion is located axially outside the non-adhesive portion, the main rubber elastomer is constrained by the inner shaft member within the adhesive portion, and its axial outward deformation is limited within the adhesive portion when input is applied in the axial right-angle direction. Therefore, a higher elastic constant resulting from compression of the main rubber elastomer in the axial right-angle direction can be achieved. Further, by providing tapered portions at both ends of the outer cylinder member in the axial direction, the axial outward deformation in the outer peripheral portion of the main rubber elastomer is limited by the tapered portions. Thus, when the main rubber elastomer is compressed in the axial right-angle direction, in the inner peripheral portion of the main rubber elastomer, the main rubber elastomer, which easily retracts axially outward due to the non-adhesive portion, is constrained by the adhesive portion, and in the outer peripheral portion of the main rubber elastomer, the retraction of the main rubber elastomer axially outward is limited by the tapered portions of the outer cylinder member. Therefore, it is possible to achieve low elasticity in the tilting and torsional directions due to the setting of non-adhesive parts, while also achieving high elasticity in the axial right-angle direction.

[0016] The second method is based on the sliding bushing described in the first method, wherein, in the main rubber elastomer, the minimum radial thickness of the portion located at the outer periphery of the non-adhesive portion is set to be smaller than the maximum radial thickness of the portion located at the outer periphery of the adhesive portion.

[0017] According to the sliding bushing configured in this manner, by making the radial thickness of the main rubber elastomer larger at the outer periphery of the adhesive portion, a longer free length of the main rubber elastomer can be ensured in the portion where durability is difficult to ensure due to adhesive constraints, thereby improving durability. On the other hand, the main rubber elastomer located at the outer periphery of the non-adhesive portion, where durability is not a problem, has a smaller radial thickness, and when vibration is input in the axial right-angle direction, it can utilize the stiffer elastic properties resulting from the compression of the non-adhesive portion.

[0018] The third method is based on the sliding bushing described in the first or second method, wherein the minimum inner diameter of the tapered portion of the outer cylinder member is smaller than the maximum outer diameter of the protrusion in the inner shaft member.

[0019] According to the sliding bushing configured in accordance with this method, the axial loosening of the inner shaft member relative to the outer cylinder member is restricted by the protrusion and the tapered portion. Furthermore, for example, during axial input, the main rubber elastomer is compressed between the protrusion and the tapered portion, thereby enabling the acquisition of a stiffer elastic characteristic resulting from the compressive elastic component in the axial direction.

[0020] The fourth method is based on the sliding bushing described in any of the first to third methods, wherein a low-friction sliding layer is provided between the non-adhesive portion of the protrusion and the overlapping surface of the main rubber elastomer.

[0021] The sliding bushing, configured according to this method, allows for more advantageous sliding between the non-adhesive portion of the inner shaft member and the main rubber elastomer, thus achieving further reduction in elasticity in both the lateral and torsional directions.

[0022] The fifth method is based on the sliding bushing described in any of the first to fourth methods, wherein a recess with an opening on the outer peripheral surface is provided in the inner shaft member at a position axially outer of the protrusion, and the adhesive portion is configured to include the inner surface of the recess.

[0023] By configuring the sliding bushing according to the structure of this method, the free length of the adhesive portion of the main rubber elastomer can be increased, thereby improving the durability of the adhesive portion.

[0024] Invention Effects

[0025] According to the present invention, the elastic properties that are relatively stiff in the right-angle direction and relatively soft in the torsional and lateral directions can be advantageously set. Attached Figure Description

[0026] Figure 1 This is a longitudinal sectional view showing the suspension bushing as a first embodiment of the present invention, which is equivalent to... Figure 2 The diagram of section II.

[0027] Figure 2 yes Figure 1 The front view of the suspension bushing is shown.

[0028] Figure 3 This is a longitudinal sectional view showing a suspension bushing as part of a second embodiment of the present invention. Detailed Implementation

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0030] exist Figure 1 , Figure 2 In the first embodiment of the sliding bushing configured according to the structure of the present invention, a suspension bushing 10 for automobiles is shown. The suspension bushing 10 has a structure in which an inner shaft member 12 and an outer cylinder member 14 are elastically connected by a main body rubber elastomer 16.

[0031] The inner shaft member 12 is, for example, a highly rigid component made of metal, and is generally configured as a small-diameter cylindrical shape. The inner shaft member 12 may be a solid rod or the like, in which case, for example, a fixing structure that can be provided at both ends of the axial direction to fix it to the suspension arm or the like.

[0032] The central portion of the inner shaft member 12 in the axial direction is constituted by a large-diameter protrusion 18 that protrudes outward. The protrusion 18 has a generally spherical outer peripheral surface that convexes outward. In the protrusion 18 of this embodiment, the inner peripheral surface is set as a curved surface corresponding to the outer peripheral surface, and the thickness is set to be approximately constant throughout the axial direction. However, the thickness of the protrusion can also vary in the axial direction; for example, the inner peripheral surface can also be set as a cylindrical surface that extends straight along the axial direction.

[0033] The portion of the inner shaft member 12 that is axially outer of the protrusion 18 is provided as a small-diameter portion 20, 20. The outer diameter of the small-diameter portion 20 is smaller than that of the protrusion 18, and it extends axially outward from the axial end of the protrusion 18. At the axial end opposite to the protrusion 18 in each small-diameter portion 20, a protrusion 22 protruding outward is provided around the entire circumference. In the small-diameter portion 20 of the inner shaft member 12, a recess 24 opening on the outer circumference is provided around the entire circumference between the protrusion 22 and the protrusion 18.

[0034] The outer cylinder member 14, like the inner shaft member 12, is configured as a highly rigid component. Compared to the inner shaft member 12, the outer cylinder member 14 is configured as a thin-walled, large-diameter, approximately cylindrical shape, and has a shorter axial length. In the outer cylinder member 14, the central portion along the axial direction is configured as a cylindrical portion 26 extending linearly along the axial direction, and tapered portions 28, 28 are provided on both axial sides of the cylindrical portion 26, which are inclined inwards towards the outer side of the axial direction. The tapered portions 28 can be inclined at a constant angle relative to the axial direction, or the inclination angle can vary axially; in this embodiment, the inclination angle relative to the axial direction decreases towards the outer side of the axial direction. The tapered portions 28 can be pre-formed during the formation of the outer cylinder member 14, or they can be formed, for example, during the diameter reduction process of the outer cylinder member 14 as described below.

[0035] By providing tapered portions 28, 28 on both axial sides of the cylindrical portion 26, thereby achieving... Figure 1 In the longitudinal section shown, the outer cylinder member 14 has a cross-sectional shape that is concave towards the inner circumference. The axial dimension of the cylindrical portion 26 of the outer cylinder member 14 is smaller than the axial length dimension of the protrusion 18, and the axial length dimension of the outer cylinder member 14 as a whole is larger than the axial length dimension of the protrusion 18.

[0036] The inner shaft member 12 is inserted into the inner circumference of the outer cylinder member 14, and the inner shaft member 12 and the outer cylinder member 14 are concentrically arranged. The inner shaft member 12 protrudes axially to both sides relative to the outer cylinder member 14. The two axial ends of the outer cylinder member 14 are located on the outer sides of the inner shaft member 12, and the protrusion 18 located on the inner side of the outer cylinder member 14 in both the axial and radial directions is arranged to be surrounded by the outer cylinder member 14 at a predetermined distance. The radial distance between the inner shaft member 12 and the outer cylinder member 14 is set to be the smallest at the axial center where the protrusion 18 and the cylindrical portion 26 are opposite each other, and gradually increases towards the outer side of the protrusion 18. The minimum inner diameter R1 of the tapered portion 28 is smaller than the maximum outer diameter R2 of the protrusion 18. More preferably, the minimum inner diameter R3 of the tapered portion 28 at the axial outer end of the portion on which the main rubber elastomer 16 is fixedly installed is smaller than the maximum outer diameter R2 of the protrusion 18, and the main rubber elastomer 16 is continuously provided axially between the axially opposing surfaces of the protrusion 18 and the tapered portion 28.

[0037] The inner shaft member 12 and the outer cylinder member 14 are elastically connected by a main body rubber elastomer 16. The main body rubber elastomer 16 is generally cylindrical and is configured to connect the opposing surfaces of the outer peripheral surface of the inner shaft member 12 and the inner peripheral surface of the outer cylinder member 14. The main body rubber elastomer 16 is formed as an integral vulcanized molded part comprising the inner shaft member 12 and the outer cylinder member 14. In the portion of the main body rubber elastomer 16 configured to directly fill the radially opposing surfaces of the inner shaft member 12 and the outer cylinder member 14, the radial thickness at both ends of the axial section is larger than that at the axial center. However, the main body rubber elastomer 16 may also extend axially with a substantially constant radial thickness.

[0038] By applying a diameter reduction process, such as deep drawing, to the outer cylinder member 14 after the main rubber elastomer 16 is vulcanized, the tensile stress caused by thermal shrinkage acting on the main rubber elastomer 16 is reduced, thereby improving the durability of the main rubber elastomer 16. Furthermore, by significantly reducing the diameter of the axial end of the outer cylinder member 14 during the diameter reduction process, tapered portions 28, 28 are formed in the outer cylinder member 14. This allows the inner shaft member 12 to be inserted into the outer cylinder member 14 before the main rubber elastomer 16 is formed, and allows the minimum inner diameter R1 of the tapered portions 28, 28 to be smaller than the maximum outer diameter R2 of the protrusion 18 after the main rubber elastomer 16 is formed. Moreover, the loosening of the inner shaft member 12 relative to the outer cylinder member 14 is prevented by the indirect engagement of the protrusion 18 and the tapered portions 28, 28 via the main rubber elastomer 16. Furthermore, the minimum inner diameter R3 of the portion in the tapered portions 28, 28 where the main rubber elastomer 16 is fixedly mounted is made smaller than the maximum outer diameter R2 of the protrusion 18, thereby enabling the acquisition of a stiffer elastic characteristic resulting from the compression of the main rubber elastomer 16 between the protrusion 18 and the tapered portions 28, 28 during axial vibration input. In addition, in Figure 1 In the diagram, the outer cylinder component 14 before the diameter reduction process is represented by a double-dotted line.

[0039] Furthermore, the outer cylinder component 14 is vulcanized and bonded to the main rubber elastomer 16. No sliding layer, as is present between the overlapping surfaces of the outer cylinder component 14 and the main rubber elastomer 16, is provided. Therefore, when the outer cylinder component 14 is reduced in diameter, no adverse conditions such as wrinkling of the sliding layer occur.

[0040] The main body rubber elastomer 16 is disposed in the axial region spanning the outer peripheral surface of the protrusion 18 in the inner shaft member 12 and the outer peripheral surface of the small diameter portions 20, 20. Furthermore, in the main body rubber elastomer 16, the two axial ends are vulcanized and bonded to the adhesive portions 30, 30 formed by the outer peripheral surfaces of the two axial sides of the inner shaft member 12, while the central axial portion overlaps with the non-adhesive portion 32 formed by the outer peripheral surface of the central axial portion of the inner shaft member 12. Additionally, the axial length of the portion of the main body rubber elastomer 16 disposed to directly fill the radially opposing surfaces of the inner shaft member 12 and the outer cylinder member 14 can be limited to the length on the outer peripheral surface of the protrusion 18 of the inner shaft member 12, or it can be the axial length extending to the small diameter portions 20, 20 extending axially from the protrusion 18 to both sides.

[0041] The adhesive portions 30, 30 are formed by the outer peripheral surface of the axial end of the protrusion 18 and the outer peripheral surface of the small-diameter portions 20, 20 constituting the axial end portions of the inner shaft member 12. In this embodiment, they are configured to include the inner surface of the recesses 24, 24 containing the small-diameter portions 20, 20. The adhesive portions 30, 30 extend to a position axially outer of the outer cylinder member 14, reaching the outer peripheral surface of the protrusions 22, 22. Furthermore, the inner peripheral portion of the main body rubber elastomer 16 has an inner fixing mounting portion 34 that is fixedly mounted to the inner surface of the recess 24. The axial inner end of the inner fixing mounting portion 34 is located at a position that offsets the recess 38 axially inward. The axial outer portion of the inner fixing mounting portion 34 is located axially outer of the deepest part of the recess 38, and the outer peripheral surface of the axial outer portion of the inner fixing mounting portion 34 is exposed. The adhesive portion 30 preferably includes the outer peripheral surface of the small-diameter portions 20, 20 protruding to both axial sides of the protrusion 18.

[0042] In this embodiment, the non-adhesive portion 32 is formed by the outer peripheral surface of the axially central portion of the protrusion 18. Because the inner shaft member 12 and the main rubber elastomer 16 are not bonded at the non-adhesive portion 32, sliding (relative displacement of the overlapping surfaces) between the inner shaft member 12 and the main rubber elastomer 16 is allowed at the non-adhesive portion 32. Furthermore, in this embodiment, the non-adhesive portion 32 is covered by a sliding layer 36 made of a low-friction coating material, making it easier for sliding between the inner shaft member 12 and the main rubber elastomer 16 to occur at the non-adhesive portion 32. The sliding layer 36 is formed by known sliding coating materials such as fluororesin or molybdenum disulfide, and is formed by known methods such as coating or vapor deposition. The non-adhesive portion 32 preferably includes the center of the protrusion 18, for example, a region extending axially outward from the maximum outer diameter of the protrusion 18 to a point reaching half the difference between the maximum and minimum outer diameter of the protrusion 18.

[0043] The outer peripheral surface of the main rubber elastomer 16 is vulcanized and bonded to the inner peripheral surface of the outer cylinder component 14. The main rubber elastomer 16 is fixedly installed on the inner peripheral surfaces of the cylindrical portion 26 and the conical portions 28, 28 in the outer cylinder component 14.

[0044] In the main body rubber elastomer 16, the minimum radial thickness W1 of the portion located at the outer periphery of the non-adhesive portion 32 is smaller than the maximum radial thickness W2 of the portion located at the outer periphery of the adhesive portion 30. Furthermore, the minimum radial thickness W1 of the portion located at the outer periphery of the non-adhesive portion 32 is smaller than the minimum radial thickness W3 of the portion in the adhesive portion 30 that continuously connects the inner shaft member 12 and the outer cylinder member 14 in the radial direction. Additionally, on the axial end face of the main body rubber elastomer 16, concave recesses 38, 38 are formed throughout the entire circumference, opening axially between the inner shaft member 12 and the outer cylinder member 14, with the bottoms of the recesses 38, 38 reaching the outer periphery of the protrusion 18. There are no particular limitations on the depth, size, or shape of the recesses 38; for example, the recesses 38 may be at a depth that does not reach the outer periphery of the protrusion 18 from the axial end face of the main body rubber elastomer 16. Alternatively, the recesses 38 may not be provided.

[0045] The suspension bushing 10 configured as described above connects the vehicle body and the suspension arm for vibration damping by mounting the inner shaft member 12 to the vehicle body side (not shown) and the outer cylinder member 14 to the suspension arm side (not shown).

[0046] If a vibration in the right-angle direction (radial) is input between the inner shaft member 12 and the outer cylinder member 14, the main rubber elastomer 16 is compressed in the right-angle direction between the inner shaft member 12 and the outer cylinder member 14, thus exhibiting the stiffer elastic properties resulting from the compression elastic component. In particular, because the inner shaft member 12 is provided with a protrusion 18, the radial thickness of the main rubber elastomer 16 is smaller on the outer periphery of the protrusion 18, so a stiffer elastic property can be obtained through the compression of the main rubber elastomer 16.

[0047] Because the main rubber elastomer 16 can slide relative to the non-adhesive portion 32 of the inner shaft member 12, which includes the outer peripheral surface of the protrusion 18, it deforms axially outward according to the shape of the outer peripheral surface of the protrusion 18 when compressed in the axial right-angle direction. Here, adhesive portions 30, 30, on both sides of the non-adhesive portion 32, are provided with vulcanized adhesive portions to which the main rubber elastomer 16 is bonded, and the deformation of the main rubber elastomer 16 is restricted at the adhesive portions 30, 30. As a result, the main rubber elastomer 16 located on the outer periphery of the non-adhesive portion 32 is difficult to deform axially outward, preventing the main rubber elastomer 16 from retreating axially outward, thereby effectively utilizing the relatively stiff elastic properties brought about by compression in the axial right-angle direction.

[0048] Furthermore, because the two axial ends of the outer cylinder member 14 are provided with tapered portions 28, 28, the outward retraction of the outer peripheral portion of the main rubber elastomer 16 is suppressed by the tapered portions 28, 28. As a result, a harder elastic property can be set more effectively in the axial right-angle direction.

[0049] In the main body rubber elastomer 16, the free length of the portion connecting the adhesive part 30 of the inner shaft member 12 and the outer cylinder member 14 is longer than the free length of the portion connecting the protrusion 18 and the outer cylinder member 14. As a result, the durability of the main body rubber elastomer 16 is improved in the part that is prone to damage due to the adhesion between the inner shaft member 12 and the outer cylinder member 14.

[0050] In this embodiment, the adhesive portion 30 of the inner shaft member 12 is configured with an inner surface including recesses 24, 24, and the recesses 24 ensure a longer free length for the portion of the adhesive portion 30 connecting the main body rubber elastomer 16 and the outer cylinder member 14. Therefore, improved durability is achieved at the connection between the adhesive portion 30 of the inner shaft member 12 and the outer cylinder member 14 in the main body rubber elastomer 16.

[0051] If a lateral vibration is input between the inner shaft member 12 and the outer cylinder member 14, the main rubber elastomer 16 undergoes shear deformation between the protrusion 18 of the inner shaft member 12 and the outer cylinder member 14, resulting in a smaller compressive elastic component and thus lower elasticity in the lateral direction. Because the inner shaft member 12 and the main rubber elastomer 16 are not bonded at the non-adhesive portion 32 located on the outer peripheral surface of the protrusion 18 and can slide, the shear elastic component is also reduced, and the elastic constant in the lateral direction is smaller. Furthermore, by providing a recess 38 on the axially outer portion of the main rubber elastomer 16 located between the adhesive portion 30 and the outer cylinder member 14, the compressive elastic component of the main rubber elastomer 16 is further reduced during lateral displacement of the inner shaft member 12 and the outer cylinder member 14.

[0052] If a torsional vibration is input between the inner shaft member 12 and the outer cylinder member 14, the main rubber elastomer 16 undergoes shear deformation between the protrusion 18 of the inner shaft member 12 and the outer cylinder member 14. The compressive elastic component is small, thus achieving lower elasticity in the torsional direction. Because the inner shaft member 12 and the main rubber elastomer 16 are configured to be non-adhesive at the non-adhesive portion 32 on the outer peripheral surface of the protrusion 18 and can slide, the shear elastic component is also reduced, and the elastic constant in the torsional direction is even smaller.

[0053] In this embodiment, a low-friction sliding layer 36 is provided in the non-adhesive portion 32 of the inner shaft member 12, reducing the frictional resistance during sliding between the non-adhesive portion 32 and the inner circumferential surface of the main rubber elastomer 16. This allows for more effective achievement of low elasticity in both the lateral and torsional directions.

[0054] exist Figure 3 The diagram shows a portion of a suspension bushing 40 as a second embodiment of the present invention. The suspension bushing 40 is configured to include an outer cylinder member 42, in which a recessed portion 44, bent outwards, is provided at a position axially outward of the tapered portion 28. In the following description, components and parts substantially the same as those in the first embodiment are omitted from description by using the same reference numerals in the drawings.

[0055] The recessed portion 44 is inclined outward toward the outer periphery. In this embodiment, the recessed portion 44 has a curved cross-sectional shape whose inclination angle relative to the axial direction increases as it moves outward toward the axial direction. By providing the recessed portion 44, the end face of the outer cylinder member 42 faces the outer periphery, and the inner circumferential surface 46 of the axial end of the outer cylinder member 42 is configured as a smooth, edgeless curved surface. Furthermore, the outer cylinder member 42 is radially opposed to the inner fixed mounting portion 34 of the main body rubber elastomer 16 at the curved inner circumferential surface 46 formed by the end of the tapered portion 28 and the recessed portion 44.

[0056] According to the suspension bushing 40 of this embodiment as described above, it is possible to prevent the edge of the axial end of the outer cylinder member 42 from contacting the main rubber elastomer 16 during vibration input, thereby avoiding damage to the main rubber elastomer 16. In addition, by providing a recessed portion 44 with a curved profile at the axial end of the outer cylinder member 42, it is also possible to improve the deformation rigidity of the outer cylinder member 42.

[0057] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific descriptions thereto. For example, the adhesive portion 30 of the inner shaft member 12 may be a part of the outer peripheral surface of the small diameter portion 20, may be the entire outer peripheral surface of the small diameter portion 20, or may include a part of the outer peripheral surface of the protrusion 18 in addition to the entire outer peripheral surface of the small diameter portion 20. Furthermore, the non-adhesive portion 32 of the inner shaft member 12 may be a part of the outer peripheral surface of the protrusion 18, may be the entire outer peripheral surface of the protrusion 18, or may include a part of the outer peripheral surface of the small diameter portion 20 in addition to the entire outer peripheral surface of the protrusion 18.

[0058] The protrusion 18 of the inner shaft member 12 can be disposed at the midpoint of the axial direction of the inner shaft member 12; for example, it can be biased in either direction of the axial direction relative to the axial center of the inner shaft member 12. The protrusion 18 is preferably located at a position corresponding to... Figure 1 The longitudinal section has an outer peripheral surface shape that is arc-shaped, but for example, an outer peripheral surface shape that is approximately trapezoidal can also be used. The recess 24 of the inner shaft member 12 is not necessary. In addition, the recess 24 can, for example, omit the protrusion 22 and open outward in the axial direction, so that the two ends of the inner shaft member 12 can also have a small diameter up to the end edge.

[0059] The inclination angles of the inner and outer circumferential surfaces of the tapered portions 28, 28 of the outer cylinder member 14 can also be different. For example, the tapered portion can be inclined inward only with its inner circumferential surface facing outward along the axial direction, or it can be a thick wall facing outward along the axial direction. In addition, the maximum outer diameter R2 of the protrusion 18 of the inner shaft member 12 can also be smaller than the minimum inner diameter R1 of the tapered portions 28, 28 of the outer cylinder member 14.

[0060] For purposes such as avoiding interference from the outer cylinder member 14 during lateral input, a recessed part that is partially open and extends circumferentially may be provided in the inner shaft member 12 and / or the main body rubber elastomer 16 fixed mounting part 34, which is opposite to the end of the outer cylinder member 14.

[0061] Although the structure coated with a material is illustrated as the sliding layer 36, the sliding layer can also be formed by overlapping the sliding liner, which is a woven material made of low-friction fibers, with the non-adhesive portion 32 of the inner shaft member 12. Furthermore, the sliding layer is not necessary, and it may not be provided entirely on the non-adhesive portion 32, but only partially on at least a portion of the non-adhesive portion 32.

[0062] The forming material of the main rubber elastomer 16 can also be a self-lubricating rubber material with a low coefficient of friction on the surface due to mixing with oil or the like, thereby further improving the sliding performance between the inner shaft member 12 and the main rubber elastomer 16.

[0063] In addition to bonding across the entire surface, the adhesive portion 30 can also be bonded at predetermined intervals in the circumferential direction, or partially bonded in multiple areas. Alternatively, the distribution and transfer of the rubber constraint force resulting from the bonding can be achieved by providing a partially bonded area or an area where the proportion of the bonded area gradually changes in the axial direction at the boundary between the adhesive portion 30 and the non-adhesive portion 32. Similarly, the non-adhesive portion 32 is not limited to being non-adhesive across the entire surface, depending on the desired elastic properties, durability, etc. Therefore, the adhesive portion and the non-adhesive portion in this invention can be interpreted as relative parts.

[0064] In the described embodiment, an example of applying the invention to suspension bushings for automobiles is shown, but the invention can also be applied to sliding bushings other than suspension bushings.

[0065] Explanation of reference numerals in the attached figures

[0066] 10: Suspension bushing (first embodiment of sliding bushing); 12: Inner shaft member; 14: Outer cylinder member; 16: Main rubber elastomer; 18: Protrusion; 20: Small diameter portion; 22: Protrusion; 24: Recess; 26: Cylindrical portion; 28: Conical portion; 30: Adhesive portion; 32: Non-adhesive portion; 34: Inner fixed mounting portion; 36: Sliding layer; 38: Recess; 40: Suspension bushing (second embodiment of sliding bushing); 42: Outer cylinder member; 44: Recessed portion; 46: Inner circumferential surface.

Claims

1. A sliding bushing (10, 40) having an inner shaft member (12) and an outer cylinder member (14, 42) connected by a main body rubber elastomer (16) and allowing the inner shaft member (12) to slide relative to the main body rubber elastomer (16), wherein, The inner shaft member (12) has a large-diameter protrusion (18) at the midpoint of its axial direction. Furthermore, the outer cylinder components (14, 42) have a tapered portion (28) with a small diameter formed by the two ends in the axial direction pointing outwards. The outer peripheral surface of the protrusion (18) in the inner shaft member (12) has a non-adhesive portion (32) that is not bonded to the main rubber elastomer (16) but allows sliding relative to the main rubber elastomer (16), and the outer peripheral surface of the inner shaft member (12) that is axially outer of the non-adhesive portion (32) has an adhesive portion (30) to which the main rubber elastomer (16) is vulcanized and bonded.

2. The sliding bushing (10, 40) according to claim 1, wherein, In the main rubber elastomer (16), the minimum radial thickness dimension (W1) of the portion located at the outer periphery of the non-adhesive portion (32) is set to be smaller than the maximum radial thickness dimension (W2) of the portion located at the outer periphery of the adhesive portion (30).

3. The sliding bushing (10, 40) according to claim 1 or 2, wherein, The minimum inner diameter (R1) of the tapered portion (28) of the outer cylinder member (14, 42) is smaller than the maximum outer diameter (R2) of the protrusion (18) of the inner shaft member (12).

4. The sliding bushing (10, 40) according to claim 1 or 2, wherein, A low-friction sliding layer (36) is provided between the non-adhesive portion (32) of the protrusion (18) and the overlapping surface of the main rubber elastomer (16).

5. The sliding bushing (10, 40) according to claim 1 or 2, wherein, A recess (24) with an opening on the outer circumferential surface is provided in the inner shaft member (12) at a position axially outer than the protrusion (18). The adhesive portion (30) is configured to include the inner surface of the recess (24).

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