Cylindrical body, vehicle damper, and method for producing cylindrical body

Abstract

A cylindrical body (3A) is provided with: a body member (10A) that is formed in a cylindrical shape; and an end member (20A, 30) that is formed from resin into a cylindrical shape and that is connected to an end of the body member (10A). The body member (10A) has an axial recess (13a) formed on a surface intersecting the axial direction of the body member (10A), and the end member (20A, 30) is formed so as to be fitted to the axial recess (13a).

Description

Cylindrical body, vehicle shock absorber, and method of manufacturing cylindrical body

[0001] The present invention relates to a cylindrical body, a vehicle shock absorber, and a method for manufacturing a cylindrical body.

[0002] A shock absorber for a vehicle, such as a front fork of a motorcycle, includes an outer tube and an inner tube that can move forward and backward relative to the outer tube. In such a shock absorber, a fiber-reinforced resin (FRP) pipe is used as the outer tube (see Patent Document 1).

[0003] JP 2009-180292 A

[0004] In the past, metal tubular members were attached to both ends of a pipe serving as an outer tube. However, the applicant of the present application has been considering using a resin tubular member instead of the metal tubular member from the viewpoints of production efficiency, weight reduction, etc. In this consideration, a demand has been raised for improving the adhesive strength of the resin tubular member to the pipe and for improving the bending strength of the tube as an assembly of the pipe and the resin tubular member.

[0005] The present invention was created in consideration of the above circumstances, and its objective is to provide a cylindrical body, a vehicle shock absorber, and a method for manufacturing a cylindrical body that can improve adhesion strength and bending strength.

[0006] In order to solve the above problem, the cylindrical body of the present invention comprises a main body member formed in a cylindrical shape, and an end member formed in a cylindrical shape from resin and connected to the end of the main body member, wherein the main body member has an axial recess or axial protrusion formed on a surface that intersects with the axial direction of the main body member, and the end member is formed to fit into the axial recess or axial protrusion.

[0007] The vehicle shock absorber of the present invention also comprises the cylindrical body, an inner tube that is inserted into the cylindrical body so as to be able to move back and forth, and a damping mechanism that applies resistance to the inner tube that has entered the cylindrical body.

[0008] The method for manufacturing a cylindrical body of the present invention includes the steps of forming the main body member and forming the end member so as to be connected to the main body member.

[0009] According to the present invention, the adhesive strength of the resin end member to the main body member can be improved, and the bending strength of the cylindrical body can also be improved.

[0010] 1 is a side view schematically showing a front part of a saddle-ride type vehicle to which a vehicle shock absorber according to a first embodiment of the present invention is applied; FIG. 2 is a front view schematically showing a front part of a saddle-ride type vehicle to which a vehicle shock absorber according to the first embodiment of the present invention is applied; FIG. 3 is a cross-sectional view schematically showing a cylindrical body as an outer tube of the vehicle shock absorber according to the first embodiment of the present invention; FIG. 4 is a cross-sectional view schematically showing one end of the cylindrical body according to the first embodiment of the present invention; FIG. 5 is a cross-sectional view schematically showing the other end of the cylindrical body according to the first embodiment of the present invention; FIG. 6 is a flow chart for explaining a method for manufacturing a cylindrical body according to the first embodiment of the present invention; FIG. 7 is a side view schematically showing a yarn feeding device; FIG. 8 is a side view schematically showing heating and pressure using a tape;

[0011] An embodiment of the present invention will be described in detail with reference to the drawings, taking as an example a case where the cylindrical body of the present invention is applied to an outer tube of a vehicle shock absorber on the front wheel side of a saddle-ride type vehicle (a vehicle with a handlebar). Examples of saddle-ride type vehicles include motorcycles, three-wheeled motor vehicles, and all-terrain vehicles. In the following description, identical elements are given the same reference numerals, and duplicated explanations will be omitted. Also, the drawings referred to are deformed for ease of understanding.

[0012] <First embodiment> As shown in Figs. 1 and 2, a vehicle shock absorber 1A according to a first embodiment of the present invention is provided for a front wheel W of a saddle-ride type vehicle (a bar-handle vehicle) 2. F It is an inverted front fork applied to the side.

[0013] The vehicle shock absorber 1A includes a pair of cylindrical bodies 3A as outer tubes, an inner tube 4, and a damping mechanism 5 on the left and right.

[0014] <Cylinder (Outer Tube)> The cylinder 3A is a cylindrical member in which the damping mechanism 5 is built into the upper part and the upper part of the inner tube 4 is housed in the lower part so that it can move back and forth (slidably). The cylinder 3A as the outer tube extends in the vertical direction and is tilted rearward as it extends upward.

[0015] The upper ends of the pair of left and right cylindrical bodies 3A are connected by an upper body bracket 2a. The lower ends of the pair of left and right cylindrical bodies 3A are connected by a lower body bracket 2b. A handlebar 2c is attached to the body bracket 2a. The body brackets 2a and 2b are connected by a rotation shaft (not shown) of the handlebar 2c, and this rotation shaft is journaled by a head pipe (not shown) of the body frame.

[0016] <Inner Tube> The inner tube 4 is a cylindrical member made of metal (iron, aluminum alloy, etc.) or fiber reinforced resin (for example, carbon fiber reinforced resin) having an outer diameter that allows it to be inserted into the cylindrical body 3A.

[0017] Axle brackets 2d are attached to the lower end of the inner tube 4. The pair of left and right axle brackets 2d are F The wheels are connected by an axle 2e, which is the rotation axis of the wheels.

[0018] <Damping Mechanism> The damping mechanism 5 is housed in the upper part of the cylindrical body 3A and applies a resistance force to the inner tube 4 that has entered the cylindrical body 3A. The damping mechanism 5 generates the resistance force such that the greater the amount of penetration of the inner tube 4 into the cylindrical body 3A, the greater the resistance force that tries to push the inner tube 4 out of the cylindrical body 3A.

[0019] <Detailed Description of Cylindrical Body> As shown in FIG. 3, the cylindrical body 3A includes a mandrel 6, a main body member 10A, an end member 20A, and an end member 30, which are arranged coaxially.

[0020] <Mandrel> The mandrel 6 is a metal (for example, aluminum) member having a substantially cylindrical shape.

[0021] <Main Body Member> The main body member 10A is a member that constitutes the axially intermediate portion of the cylindrical body 3A, and is a resin layer that is formed in a cylindrical shape on the outer peripheral surface of the mandrel 6. The main body member 10A is a fiber-reinforced resin layer, more specifically, a carbon fiber-reinforced resin layer. The resin used as the material for the main body member 10A is a thermoplastic resin (e.g., polyamide).

[0022] 4, 5, and 11, the main body member 10A integrally and coaxially comprises a first outer diameter portion 11 constituting an axially intermediate portion of the main body member 10A and a pair of second outer diameter portions 12, 12 constituting both axial ends of the main body member 10A. The main body member 10A includes, as surfaces intersecting the axial direction, a boundary surface 13 that is a boundary (step portion) between the first outer diameter portion 11 and the second outer diameter portion 12, and an axial end surface 14 that is a tip end of the second outer diameter portion 12. The inner diameters of the first outer diameter portion 11 and the second outer diameter portion 12 are equal to the outer diameter of the mandrel 6. The outer diameter of the second outer diameter portion 12 is smaller than the outer diameter of the first outer diameter portion 11.

[0023] The main body member 10A includes an axial recess 13a, a rough surface portion 12a, and a radial recess 12b as portions that strengthen the bond with the end members 20A and 30.

[0024] <Axial Recess> The axial recess 13a is a groove formed in the boundary surface 13 in an annular shape around the axis of the main body member 10A.

[0025] Rough Surface Portion The rough surface portion 12a is formed in an annular shape around the axis of the main body member 10A on a portion of the outer peripheral surface of the second outer diameter portion 12. The rough surface portion 12a is formed so that its surface area per unit distance in the axial direction is larger than that of a portion of the outer peripheral surface of the second outer diameter portion 12 where the rough surface portion 12a and the radial recesses 12b are not formed. In this embodiment, the rough surface portion 12a is formed by cutting a spiral groove in a portion of the outer peripheral surface of the second outer diameter portion 12. The groove is shallower than the radial recesses 12b. The rough surface portion 12a is processed to have an Rz of 50 μm to 100 μm, and is formed so that its area is 105% to 120% (the increase in surface area is 5% to 20%) compared to when the rough surface portion 12a is not roughened. That is, when the surface area per unit distance in the axial direction of the second outer diameter portion 12 on which the rough surface portion 12a is not formed (the surface area of ​​a predetermined projected range as viewed from the radial direction) is taken as 100, the surface area per unit distance in the axial direction of the rough surface portion 12a (the surface area of ​​a predetermined projected range as viewed from the radial direction) is 105 to 120. When the area increase rate of the rough surface portion 12a is 5% or more, it is possible to improve adhesion with the end members 20A, 30 and realize improved strength against peeling and improved strength against axial loads. Furthermore, when the area increase rate of the rough surface portion 12a is 20% or less, it is possible to realize ease of processing.

[0026] <Radial Recess> The radial recess 12b is a groove formed in an annular shape around the axis of the main body member 10A in a part of the outer circumferential surface of the second outer diameter portion 12. In the present embodiment, the radial recess 12b is provided axially outward from the rough surface portion 12a.

[0027] 3, the end member 20A is a member connected to the end (upper end) of the main body member 10A and serves as a fork bolt attachment portion to which a fork bolt is attached. The end member 20A is a fiber-reinforced resin layer, more specifically, a carbon fiber-reinforced resin layer. The resin used as the material for the end member 20A is a thermoplastic resin (e.g., polyamide).

[0028] 4 and 11 , the end member 20A integrally and coaxially includes an overlapping portion 21 that overlaps with the second outer diameter portion 12 of the main body member 10A in the axial direction, and a protruding portion 22 that protrudes from the main body member 10A in the axial direction. The end member 20A includes, as surfaces intersecting the axial direction, an axial end surface 23 that is the tip of the overlapping portion 21, and a boundary surface 24 that is the boundary (step portion) between the overlapping portion 21 and the protruding portion 22. The axial end surface 23 abuts against the boundary surface 13 of the main body member 10A, and the boundary surface 24 abuts against the axial end surface 14 of the main body member 10A. The inner diameter of the overlapping portion 21 is equal to the outer diameter of the second outer diameter portion 12. The inner diameter of the protruding portion 22 is smaller than the inner diameters of the first outer diameter portion 11 and the second outer diameter portion 12 and is equal to the inner diameter of the mandrel 6.

[0029] The end member 20A is formed by injection molding so as to be connected to the main body member 10A. That is, the inner peripheral surface of the overlapping portion 21 is shaped to conform to the outer peripheral surface of the second outer diameter portion 12 and is welded to the outer peripheral surface. The axial end face 23 is shaped to conform to the boundary surface 13 and is welded to the boundary surface 13. The boundary surface 24 is shaped to conform to the axial end face 14 and is welded to the axial end face 14.

[0030] The end member 20A has an axial convex portion 23a and a radial convex portion 21b as portions that strengthen the connection with the main body member 10A.

[0031] <Axial Convex Portion> The axial convex portion 23a is an annular protrusion formed to protrude in the axial direction from the axial end surface 23 of the end member 20A (overlapping portion 21). The axial convex portion 23a is formed to enter and fit into the axial concave portion 13a of the main body member 10A.

[0032] <Radial Convex Portion> The radial convex portion 21b is a protrusion formed in a ring shape around the axis of the end member 20A on a part of the inner circumferential surface of the overlapping portion 21.

[0033] Furthermore, a portion of the inner peripheral surface of the overlapping portion 21 that is axially inward of the radial protrusion 21b is welded to the rough surface portion 12a.

[0034] 3, the end member 30 is a member connected to the end (lower end) of the main body member 10A and is an oil seal press-fitting portion into which an oil seal is press-fitted. The end member 30 is a fiber-reinforced resin layer, more specifically, a carbon fiber-reinforced resin layer. The resin used as the material for the end member 30 is a thermoplastic resin (e.g., polyamide).

[0035] As shown in FIG. 5 , the end member 30 integrally and coaxially includes an overlapping portion 31 that overlaps with the second outer diameter portion 12 of the main body member 10A in the axial direction, and a protruding portion 32 that protrudes from the main body member 10A in the axial direction. The end member 30 includes, as surfaces intersecting the axial direction, an axial end surface 33 that is the tip of the overlapping portion 31, and a boundary surface 34 that is the boundary (step portion) between the overlapping portion 31 and the protruding portion 32. The axial end surface 33 abuts against the boundary surface 13 of the main body member 10A, and the boundary surface 34 abuts against the axial end surface 14 of the main body member 10A. The inner diameter of the overlapping portion 31 is equal to the outer diameter of the second outer diameter portion 12. The inner diameter of the protruding portion 32 is smaller than the inner diameters of the first outer diameter portion 11 and the second outer diameter portion 12 and is equal to the inner diameter of the mandrel 6.

[0036] The end member 30 is formed by injection molding so as to be connected to the main body member 10A. That is, the inner peripheral surface of the overlapping portion 31 is shaped to conform to the outer peripheral surface of the second outer diameter portion 12 and is welded to the outer peripheral surface. The axial end face 33 is shaped to conform to the boundary surface 13 and is welded to the boundary surface 13. The boundary surface 34 is shaped to conform to the axial end face 14 and is welded to the axial end face 14.

[0037] The end member 30 has an axial convex portion 33a and a radial convex portion 31b as portions that strengthen the connection with the main body member 10A.

[0038] <Axial Convex Portion> The axial convex portion 33a is an annular protrusion formed to protrude in the axial direction from the axial end surface 33 of the end member 30 (overlapping portion 31). The axial convex portion 33a is formed to enter and fit into the axial concave portion 13a of the main body member 10A.

[0039] <Radial Convex Portion> The radial convex portion 31 b is a protrusion formed in an annular shape around the axis of the end member 30 on a part of the inner circumferential surface of the overlapping portion 31 .

[0040] Furthermore, a portion of the inner peripheral surface of the overlapping portion 31 that is axially inward of the radial protrusion 31b is welded to the rough surface portion 32a.

[0041] <Connection between Main Body Member and End Member> The axial protrusion 23a (33a) of the end member 20A (30) is formed to enter at least a portion of the axial recess 13a of the main body member 10A and engage with the axial recess 13a. This engagement prevents the end member 20A (30) from peeling off from the main body member 10A when bending is applied to the cylindrical body 3A, and prevents cracking of the contact surfaces between the end member 20A (30) and the main body member 10A in the axial direction. In other words, this engagement can improve the adhesion strength and bending strength of the cylindrical body 3A.

[0042] Specifically, the axial convex portion 23a (33a) and the axial concave portion 13a are formed on the radial inside of the axial end face 23 and the boundary surface 13. When bending is input to the cylindrical body 3A, the axial tip end portion of the first outer diameter portion 11 presses down on the axial convex portion 23a (33a) from the radial outside, thereby preventing the end member 20A (30) from peeling off from the main body member 10A.

[0043] The inner peripheral surface of the overlapping portion 21 (31) of the end member 20A (30) is formed to penetrate into the rough surface portion 12a of the main body member 10A and is welded thereto. This penetration increases the welding area of ​​the end member 20A (30) to the main body member 10A. In other words, this penetration prevents the end member 20A (30) from peeling off from the main body member 10A when bending input is applied to the cylindrical body 3A and when the cylindrical body 3A expands. Furthermore, this penetration improves the strength of the cylindrical body 3A against axial loads.

[0044] The radial protrusion 21b (31b) of the end member 20A (30) is formed to fit into the radial recess 12b of the main body member 10A. This fit improves the tensile strength and compressive strength when an axial load is applied to the cylindrical body 3A. That is, this fit improves the axial shear strength of the cylindrical body 3A.

[0045] <Method for Manufacturing Cylindrical Body> Next, a method for manufacturing the cylindrical body 3A will be described with reference to the flowchart of FIG. 6 (and also with reference to FIGS. 3 to 5 as appropriate).

[0046] First, the main body member 10A is formed (step S1). Specifically, a yarn supplying device 7 (see FIG. 7 ) places a fibrous body 10a (a bundle of multiple fibers) of the main body member 10A on the outer circumferential surface of a mandrel precursor 6X, which is a pre-completed member of the mandrel 6. As shown in FIG. 7 , the yarn supplying device 7 includes multiple yarn supplying units 7a arranged circumferentially. The yarn supplying units 7a supply the fibrous body 10a partially impregnated with a thermoplastic resin 10b. In this embodiment, the yarn supplying device 7 rotates while a moving device (not shown) moves the mandrel precursor 6X in the axial direction of the mandrel precursor 6X, with an end of the fibrous body 10a fixed to one end of the mandrel precursor 6X. This allows the fibrous body 10a to be arranged (wound) at a desired orientation angle on the outer circumferential surface of the mandrel precursor 6X.

[0047] In this embodiment, the yarn supplying device 7 uses a multiple filament winding (MFW) method to arrange multiple layers of fibrous bodies 10a on the outer circumferential surface of the mandrel precursor 6X. Because the multiple layers of fibrous bodies 10a arranged using the MFW method are not interwoven with each other and do not have entangled portions, the fibrous bodies 10a can be arranged densely, improving the strength of the tubular body 3A compared to when entangled portions are present. Furthermore, the tubular body 3A including the fibrous bodies 10a manufactured using the MFW method can reduce the amount of fibrous bodies 10a required for the required strength.

[0048] Next, a heating device (not shown) applies heat to the fibrous body 10a via the tape 8 wound around the outer periphery of the fibrous body 10a, thereby impregnating the fibrous body 10a, which is pressurized by the tape 8, with the thermoplastic resin 10b (see FIG. 8). This allows the thermoplastic resin 10b to spread evenly throughout the entire fibrous body 10a without creating gaps. The thermoplastic resin 10b is then cured. This forms a main body member precursor 10AX, a pre-finished component of the main body member 10A, on the outer periphery of the mandrel precursor 6X (see FIG. 9).

[0049] Next, a processing device (such as a cutting device) not shown processes (cuts) the mandrel precursor 6X and processes (cuts) the outer surface of the main body member precursor 10X to form the mandrel 6 and the main body member 10A (see Figures 10 and 11).

[0050] Next, using an injection molding method, end members 20A, 30 are formed so as to be connected to main body member 10A (step s2). Specifically, the assembly of mandrel 6 and main body member 10A is placed in molding device 9. Here, both axial ends of the assembly are blocked with plug members P (see FIG. 12). Next, resin 20a containing fibers (single fibers) 20b is injected (injected) into molding device 9 through injection passage 9a to form end member precursors 20AX, 30X, which are components before the end members 20A, 30 are completed (see FIG. 13).

[0051] Next, the assembly of the mandrel 6, main body member 10A, plug member P, and end member precursors 20AX, 30X is removed from the molding device 9. Next, the plug member P is removed from the assembly. Next, a processing device (cutting device, etc.) (not shown) processes (cuts) the end member precursors 20AX, 30X to form the end members 20A, 30. Through these steps, the cylindrical body 3A is completed.

[0052] A cylindrical body 3A according to a first embodiment of the present invention includes a cylindrical main body member 10A and cylindrical end members 20A, 30 formed from resin and connected to the ends of the main body member 10A. The main body member 10A has an axial recess 13a or an axial protrusion formed on a surface intersecting the axial direction of the main body member 10A, and the end members 20A, 30 are formed to fit into the axial recess 13a or the axial protrusion. Therefore, the cylindrical body 3A including the resin end members 20A, 30 can have improved adhesion strength and bending strength. Furthermore, the cylindrical body 3A can be made lighter and more efficient in production.

[0053] In the cylindrical body 3A, the main body member 10A has a rough surface portion 12a formed on the outer circumferential surface of the main body member 10A, and the end members 20A, 30 are welded to the rough surface portion 12a. Therefore, the cylindrical body 3A can effectively prevent the end members 20A, 30 from peeling off from the main body member 10A.

[0054] In the cylindrical body 3A, the surface area increase rate of the rough surface portion 12a is 5% to 20%. Therefore, the cylindrical body 3A can achieve both improved strength against peeling and improved strength against axial loads, and ease of processing.

[0055] In the cylindrical body 3A, the main body member 10A has a radial recess 12b or a radial protrusion formed on the outer circumferential surface of the main body member 10A, and the end members 20A, 30 are formed to fit into the radial recess 12b or the radial protrusion, thereby improving the shear strength of the cylindrical body 3A in the axial direction.

[0056] In the cylindrical body 3A, the main body member 10A is formed of carbon fiber reinforced resin, which improves the weldability of the end members 20A and 30 to the main body member 10A, and also makes the cylindrical body 3A lighter in weight and more recyclable.

[0057] In the cylindrical body 3A, the end members 20A and 30 have surfaces (boundary surfaces 24 and 34) that abut against the axial end surface 14 of the main body member 10A. Therefore, the cylindrical body 3A can have improved compressive strength in the axial direction.

[0058] In the cylindrical body 3A, the main body member 10A has a first outer diameter portion 11 and a second outer diameter portion 12 that extends axially outward from the first outer diameter portion 11 and has an outer diameter smaller than that of the first outer diameter portion 11, and the end members 20A, 30 are formed to cover the second outer diameter portion 12 from the radially outer side. Therefore, the cylindrical body 3A can facilitate the formation of the end members 20A, 30. Furthermore, the cylindrical body 3A can improve the workability of the welding portion and / or the fitting portion of the main body member 10A by, for example, forming a rough surface portion 12a and / or a radial recess 12b or a radial protrusion on the outer peripheral surface of the second outer diameter portion 12.

[0059] In the cylindrical body 3A, the axial recess 13a or the axial protrusion is provided on the boundary surface 13 between the first outer diameter portion 11 and the second outer diameter portion 12. Therefore, the cylindrical body 3A can suitably prevent peeling at the step portion of the main body member 10A when a bending input is applied.

[0060] The cylindrical body 3A is an outer tube of the vehicle shock absorber 1A, and therefore, the cylindrical body 3A can achieve suitable mechanical characteristics in the vehicle shock absorber 1A, which is subjected to bending, compression, and tension in the axial direction.

[0061] The vehicle shock absorber 1A according to the first embodiment of the present invention includes a cylindrical body 3A, an inner tube 4 that is inserted into the cylindrical body 3A so as to be able to advance and retreat, and a damping mechanism 5 that applies resistance to the inner tube 4 that has advanced into the cylindrical body 3A. Therefore, the vehicle shock absorber 1A can achieve suitable mechanical properties against bending, compression, and tension in the axial direction.

[0062] The manufacturing method of the cylindrical body 3A according to the first embodiment of the present invention includes the steps of forming the main body member 10A and forming the end members 20A, 30 so as to be connected to the main body member 10A. Therefore, the manufacturing method of the cylindrical body 3A can manufacture a cylindrical body 3A with improved adhesion strength and bending strength. Furthermore, the manufacturing method of the cylindrical body 3A can improve production efficiency and reduce the weight of the cylindrical body 3A.

[0063] Second Embodiment Next, a cylindrical body according to a second embodiment of the present invention will be described, focusing on the differences from the cylindrical body 3A according to the first embodiment. As shown in Fig. 14, the cylindrical body 3B according to the second embodiment of the present invention includes a main body member 10B and an end member 20B instead of the main body member 10A and the end member 20A.

[0064] <Main Body Member> The main body member 10B includes an axial recess 14a instead of the axial recess 13a as a portion for strengthening the connection with the end member 20B.

[0065] <Axial Recess> The axial recess 14a is a groove formed in an annular shape around the axis of the main body member 10B on the axial end surface 14.

[0066] <End Member> The end member 20B includes an axial convex portion 24a instead of the axial convex portion 23a as a portion that strengthens the bond with the main body member 10B.

[0067] <Axial Convex Portion> The axial convex portion 24a is an annular protrusion formed to protrude in the axial direction from the boundary surface 24 of the end member 20B. The axial convex portion 24a is formed to enter and fit into the axial concave portion 14a of the main body member 10B.

[0068] The axial convex portion 24a and the axial concave portion 14a are formed at the radially intermediate portion of the boundary surface 24 and the axial end surface 14. When bending is applied to the cylindrical body 3B, the axial tip portion of the second outer diameter portion 12 presses down on the axial convex portion 24a from the radially outer side and the radially inner side, thereby preventing the end member 20B from peeling off from the main body member 10B.

[0069] In the cylindrical body 3B according to the second embodiment of the present invention, the axial recess 14a or the axial protrusion is provided on the axial end surface 14 of the second outer diameter portion 12. Therefore, the cylindrical body 3B can suitably prevent peeling at the tip end of the main body member 10B when a bending input is applied.

[0070] Third Embodiment Next, a cylindrical body according to a third embodiment of the present invention will be described, focusing on the differences from the cylindrical body 3A according to the first embodiment. As shown in Fig. 15, a cylindrical body 3C according to the third embodiment of the present invention includes a main body member 10C and an end member 20C instead of the main body member 10A and the end member 20A.

[0071] <Main Body Member> Instead of the first outer diameter portion 11 and one of the second outer diameter portions 12, the main body member 10C integrally and coaxially includes a first inner diameter portion 16 constituting an axial intermediate portion of the main body member 10C and a second inner diameter portion 17 constituting one axial end portion of the main body member 10C. The first inner diameter portion 16 has a shape similar to that of the first outer diameter portion 11. The main body member 10C includes, as surfaces intersecting the axial direction, a boundary surface 18 that is a boundary portion (step portion) between the first inner diameter portion 16 and the second inner diameter portion 17, and an axial end surface 19 that is a tip portion of the second inner diameter portion 17. The inner diameter of the first inner diameter portion 16 is equal to the outer diameter of the mandrel 6, and the inner diameter of the second inner diameter portion 17 is larger than the inner diameter of the first inner diameter portion 16 but smaller than the outer diameter of the first inner diameter portion 16.

[0072] The main body member 10C includes an axial recess 18a and an axial protrusion 19a as portions that strengthen the connection with the end member 20C.

[0073] <Axial Recess> The axial recess 18a is a groove formed in the boundary surface 18 in an annular shape around the axis of the main body member 10C.

[0074] <Axial Convex Portion> The axial convex portion 19a is a protrusion formed in an annular shape around the axis of the main body member 10C on the axial end surface 19.

[0075] <End Member> The end member 20C integrally and coaxially includes an overlapping portion 26 that overlaps with the second inner diameter portion 17 of the main body member 10C in the axial direction, and a protruding portion 27 that protrudes from the main body member 10C in the axial direction. The end member 20C includes, as surfaces intersecting the axial direction, an axial end face 28 that is the tip of the overlapping portion 26, and a boundary surface 29 that is the boundary (step portion) between the overlapping portion 26 and the protruding portion 27. The inner diameter of the overlapping portion 26 is equal to or smaller than the inner diameter of the first inner diameter portion 16 and, in this embodiment, is equal to the inner diameter of the mandrel 6. The outer diameter of the overlapping portion 26 is equal to the inner diameter of the second inner diameter portion 17. The outer diameter of the protruding portion 27 is equal to the outer diameter of the second inner diameter portion 17.

[0076] The end member 20C is formed by injection molding so as to be connected to the main body member 10C. That is, the outer peripheral surface of the overlapping portion 26 is shaped to conform to the inner peripheral surface of the second inner diameter portion 17 and is abutted against and welded to the inner peripheral surface. The axial end face 28 is shaped to conform to the axial end face 23 and is abutted against and welded to the axial end face 23. The boundary surface 29 is shaped to conform to the axial end face 19 and is abutted against and welded to the axial end face 19.

[0077] The end member 20C includes an axial convex portion 28a and an axial concave portion 29a as portions that strengthen the connection with the main body member 10C.

[0078] <Axial Convexity> The axial convexity 28a is an annular protrusion formed to protrude in the axial direction from the axial end surface 28 of the end member 20C (overlapping portion 26). The axial convexity 28a is formed to enter at least a part of the axial concave portion 18a of the main body member 10C and fit into the axial concave portion 18a.

[0079] <Axial Recess> The axial recess 29a is a groove formed in an annular shape around the axis of the end member 20C in the boundary surface 29. The axial recess 29a is formed so that the axial protrusion 19a of the main body member 10C enters at least a portion of the axial recess 29a and fits into the axial recess 29a.

[0080] The axial convex portion 28a and the axial concave portion 18a are formed on the radial outside of the axial end face 28 and the boundary surface 18. When bending is applied to the cylindrical body 3C, the axial tip end portion of the first inner diameter portion 16 presses down on the axial convex portion 28a from the radial inside, thereby preventing the end member 20C from peeling off from the main body member 10C.

[0081] The axial convex portion 19a and the axial concave portion 29a are formed on the radial inside of the axial end face 19 and the boundary surface 29. When bending is applied to the cylindrical body 3C, the axial base end portion of the protrusion 27 presses down on the axial convex portion 19a from the radial outside, thereby preventing the end member 20C from peeling off from the main body member 10C.

[0082] In a cylindrical body 3C according to a third embodiment of the present invention, the main body member 10C has a first inner diameter portion 16 and a second inner diameter portion 17 that extends axially outward from the first inner diameter portion 16 and has an inner diameter larger than that of the first inner diameter portion 16, and the end member 20C is formed so as to cover the second inner diameter portion 17 from the radially inside. Therefore, the cylindrical body 3C can reduce the exposed portion of the end member 20C and suitably protect the end member 20C.

[0083] In the cylindrical body 3C, the axial recess 18a or the axial protrusion is formed on the boundary surface 18 between the first inner diameter portion 16 and the second inner diameter portion 17. Therefore, the cylindrical body 3C can suitably prevent peeling at the step portion of the main body member 10C when a bending input is applied.

[0084] In the cylindrical body 3C, the axial recess or the axial protrusion 19a is provided on the axial end surface 19 of the second inner diameter portion 17. Therefore, the cylindrical body 3C can suitably prevent peeling at the tip end of the main body member 10C when a bending input is applied.

[0085] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified as appropriate without departing from the gist of the present invention. For example, the cylindrical body of the present invention can be applied to devices other than vehicle shock absorbers. Furthermore, the vehicle shock absorber of the present invention can be applied to vehicles other than saddle-ride vehicles (four-wheeled automobiles, etc.). Furthermore, the main body members 10A, 10B, and 10C are not limited to members made of fiber-reinforced resin using thermoplastic resin, but may also be members made of fiber-reinforced resin using thermosetting resin, or may be members made of metal.

[0086] Furthermore, the cylindrical body 3A according to the first embodiment may be configured to include, instead of the axial recess 13a and the axial protrusion 23a, an axial protrusion formed on the boundary surface 13 and an axial recess formed on the axial end surface 23. Similarly, the cylindrical body 3B according to the second embodiment may be configured to include, instead of the axial recess 14a and the axial protrusion 24a, an axial protrusion formed on the axial end surface 14 and an axial recess formed on the boundary surface 24.

[0087] DESCRIPTION OF SYMBOLS 1A... Vehicle shock absorber 2... Saddle-ride type vehicle 3A, 3B, 3C... Cylindrical body (outer tube) 4... Inner tube 5... Damping mechanism 6... Mandrel 10A, 10B, 10C... Main body member 11... First outer diameter portion 12... Second outer diameter portion 12a... Rough surface portion 12b... Radial recess 13... Boundary surface 13a... Axial recess 14... Axial end face 14a... Axial recess 16... First inner diameter portion 17... Second inner diameter portion 18... Boundary surface 18a... Axial recess 19... Axial end face 19a... Axial protrusion 20A, 20B, 20C... End member 21... Overlapping portion 21b... Radial protrusion 22... Protrusion 23... Axial end face 23a... Axial protrusion 24... Boundary surface 24a... Axial protrusion 26... Overlapping portion 27... Protrusion 28... Axial end surface 28a... Axial convex portion 29... Boundary surface 29a... Axial concave portion

Claims

1. A cylindrical body comprising: a main body member formed in a cylindrical shape; and an end member formed in a cylindrical shape from resin and connected to an end of the main body member, wherein the main body member has an axial recess or an axial protrusion formed on a surface that intersects with the axial direction of the main body member, and the end member is formed to fit into the axial recess or the axial protrusion.

2. A cylindrical body according to claim 1, wherein the main body member has a rough surface portion formed on the outer circumferential surface of the main body member, and the end member is welded to the rough surface portion.

3. The cylindrical body according to claim 2, wherein the surface area increase rate of the rough surface portion is 5% to 20%.

4. A cylindrical body according to claim 1, wherein the main body member has a radial recess or a radial protrusion formed on the outer circumferential surface of the main body member, and the end member is formed to fit into the radial recess or the radial protrusion.

5. The cylindrical body according to claim 1, wherein the main body member is formed from carbon fiber reinforced resin.

6. The cylindrical body according to claim 1, wherein the end member has a surface that abuts against the axial end surface of the main body member.

7. A cylindrical body as described in claim 6, wherein the main body member has a first outer diameter portion and a second outer diameter portion extending axially outward from the first outer diameter portion and having an outer diameter smaller than that of the first outer diameter portion, and the end member is formed so as to cover the second outer diameter portion from the radially outer side.

8. The cylindrical body according to claim 7, wherein the axial recess or the axial protrusion is provided on the boundary surface between the first outer diameter portion and the second outer diameter portion.

9. The cylindrical body according to claim 7, wherein the axial recess or the axial protrusion is provided on the axial end surface of the second outer diameter portion.

10. A cylindrical body as described in claim 6, wherein the main body member has a first inner diameter portion and a second inner diameter portion extending axially outward from the first inner diameter portion and having an inner diameter larger than that of the first inner diameter portion, and the end member is formed so as to cover the second inner diameter portion from the radially inside.

11. The cylindrical body according to claim 10, wherein the axial recess or the axial protrusion is formed on the boundary surface between the first inner diameter portion and the second inner diameter portion.

12. The cylindrical body according to claim 10, wherein the axial recess or the axial protrusion is provided on the axial end surface of the second inner diameter portion.

13. A cylindrical body according to any one of claims 1 to 12, characterized in that it is an outer tube of a vehicle shock absorber.

14. A vehicle shock absorber comprising: a cylindrical body as claimed in claim 13; an inner tube inserted into said cylindrical body so as to be able to advance and retreat; and a damping mechanism that applies resistance to said inner tube that has advanced into said cylindrical body.

15. A method for manufacturing a cylindrical body according to any one of claims 1 to 12, comprising the steps of: forming the main body member; and forming the end members so as to be connected to the main body member.

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