Shock absorber and method of manufacturing the same

Abstract

To provide a shock absorber capable of securing a coming-off load of a bumper cap and preventing a crack at attachment of the bumper cap, and a method of manufacturing the shock absorber.SOLUTION: A protrusion 21 protruding to a radial outer side is formed on one end 11 in an axial direction of a cylinder 10, a stopper 41 protruding to a radial inner side is formed on a cylinder 36 of a bumper cap 30, and an end surface 43 on one end side in the axial direction of the stopper 41 is abutted on a receiving surface 24 on the other end side in the axial direction of the protrusion 21. Therefore, the end surface 43 of the stopper 41 is received by the receiving surface 24 of the protrusion 21, and thus, a coming-off load of the bumper cap 30 can be secured, and a crack of the bumper cap 30 can be prevented.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shock absorber and a method for manufacturing a shock absorber. [Background technology]

[0002] Patent Document 1 discloses a bump stopper S that includes a cylindrical main body 1 with a bottom and a plurality of protrusions 6 protruding inward from a tubular portion 2 of the main body 1. In the bump stopper S described in Patent Document 1 (hereinafter referred to as a "conventional bumper cap"), an outer shell 11 (cylinder) is inserted and the tubular portion 2 is pushed open, so that the protrusions 6 bind the outer shell 11 and are fixed to the outer shell 11. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-025950 A Summary of the Invention [Problem to be solved by the invention]

[0004] With conventional bumper caps, if the interference between the protrusion and the outer shell is increased in order to ensure the pull-out load, there is a risk of cracking during installation. An object of the present invention is to provide a shock absorber and a method for manufacturing a shock absorber in which the removal load of a bumper cap is ensured and cracks caused when the bumper cap is attached are prevented. [Means for solving the problem]

[0005] The shock absorber of the present invention is characterized in having a protrusion formed at one axial end of the cylinder and protruding radially outward from a side wall of the cylinder, and a stopper portion formed radially inward of the tubular portion and abutting against the protrusion. The manufacturing method of the shock absorber of the present invention is characterized by including the steps of fixing a cylinder to a fixing jig, moving a bumper cap axially relative to the cylinder and positioning the stopper portion on the other axial end side of the cylinder relative to the protrusion, and rotating the bumper cap and abutting the stopper portion to the protrusion. Effect of the Invention

[0006] According to the present invention, it is possible to provide a shock absorber and a method for manufacturing a shock absorber in which the removal load of the bumper cap is ensured and cracks occurring when the bumper cap is attached can be prevented. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is an explanatory diagram of the shock absorber according to the first embodiment, showing a part of a bumper cap attached to a cylinder in a cutaway view. [Diagram 2] 2 is a view taken along the line AA in FIG. 1, showing only the bumper cap. [Diagram 3] 2 is a view taken along the arrow BB in FIG. 1, showing only the cylinder. [Figure 4] 4 is a flowchart of a method for manufacturing a shock absorber according to the first embodiment. [Diagram 5] FIG. 4 is an explanatory diagram of the manufacturing method of the shock absorber according to the first embodiment, showing a process of moving the bumper cap covering the cylinder toward the other axial end side. [Figure 6] 5 is an explanatory diagram of a manufacturing method for the shock absorber according to the first embodiment, showing a state in which a stopper portion is disposed on the other axial end side of the protrusion. FIG. [Figure 7] FIG. 4 is an explanatory diagram of the manufacturing method of the shock absorber according to the first embodiment, showing a state in which the stopper portion is in contact with the protrusion portion. [Figure 8] FIG. 13 is an explanatory diagram of a modified example of the second embodiment, showing an aspect in which the stopper portion is formed in a circular shape. [Figure 9] FIG. 13 is an explanatory diagram of a modified example of the second embodiment, showing an aspect in which the stopper portion is formed into a vertically long rectangle. [Figure 10] FIG. 13 is an explanatory diagram of a third embodiment, and is a conceptual diagram showing a state before a protrusion engages with a step portion. [Figure 11] FIG. 13 is an explanatory diagram of a third embodiment, and is a conceptual diagram showing a state in which a protrusion is engaged with a step portion. [Figure 12] FIG. 13 is an explanatory diagram of the fourth embodiment, showing an aspect in which a spacer is used. [Figure 13] FIG. 13 is an explanatory diagram of the fourth embodiment, showing a state in which a spacer is not used. [Figure 14] FIG. 13 is an explanatory diagram of the fifth embodiment, showing a state in which the protrusion is in contact with an end face of the second groove portion of the stopper portion. [Figure 15] FIG. 11 is an explanatory diagram of a jig for rotating the bumper cap. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (First embodiment) A first embodiment of the present invention will now be described with reference to the accompanying drawings. The shock absorber 1 according to the first embodiment is a hydraulic shock absorber that constitutes a suspension device for an automobile.

[0009] As shown in Fig. 1, the shock absorber 1 has a cylinder 10 in which a working fluid is sealed. The shock absorber 1 has a piston rod 3 that protrudes from an end face 12 of one axial end 11 of the cylinder 10. The shock absorber 1 has a bump stop rubber 5 attached to one axial end (not shown) of the piston rod 3. A bumper cap 30 is attached to one axial end 11 of the cylinder 10. The bumper cap 30 receives the bump stop rubber 5 at a bottom 31 when the piston rod 3 retracts.

[0010] As shown in Fig. 1 or 2, a plurality of (four in this embodiment) protrusions 21 that protrude radially outward from the cylinder 10 are formed on the outer circumferential surface 14 (side wall) of one axial end 11 of the cylinder 10. The plurality of protrusions 21 are arranged at equal intervals in the circumferential direction of the cylinder 10. The protrusions 21 have a guide surface 22 that is formed in a rectangular (square) shape when viewed from the front (see Fig. 1). The guide surface 22 is formed by a curved surface (part of the cylindrical surface) that coincides with a cylindrical surface coaxial with the cylinder 10.

[0011] The protrusion 21 has an end face 23 facing one axial end side of the cylinder 10 (the "upper side" in FIG. 1). The end face 23 is provided parallel to a plane perpendicular to the axis L of the cylinder 10 (hereinafter referred to as the "axial perpendicular plane of the cylinder 10"). The protrusion 21 has a receiving surface 24 facing the other axial end side of the cylinder 10 (the "lower side" in FIG. 1). The receiving surface 24 is provided parallel to the end face 23. The protrusion 21 has a pair of end faces 25, 26 that are provided symmetrically with respect to the axial plane of the cylinder 10 that passes through the center point of the guide surface 22. The edges between the guide surface 22 and each face (23, 24, 25, 26) adjacent to the guide surface 22 are chamfered (reference numerals omitted).

[0012] The bumper cap 30 is a resin molded part formed into a cylindrical shape with a bottom, and has a bottom 31 and a tubular portion 36 as shown in Fig. 1 or 3. A hole 32 through which the piston rod 3 is inserted is formed in the center of the bottom 31. An annular abutment surface 33 is formed on the outer circumferential edge portion of the surface on the other end side (the "lower side" in Fig. 1) of the bottom 31, against which the outer circumferential edge portion 13 of one axial end portion 11 of the cylinder 10 abuts. An annular step portion 34 is formed between the hole 32 and the abutment surface 33 on the surface on the other end side (the "lower side" in Fig. 1) of the bottom 31.

[0013] The tubular portion 36 has an inner cylindrical surface 37 that is guided by the guide surfaces 22 of the multiple protrusions 21 of the cylinder 10. The fit between the inner cylindrical surface 37 of the tubular portion 36 and the guide surfaces 22 (outer cylindrical surface) of the protrusions 21 is set so that the diameter of the tubular portion 36 is not expanded and no play occurs between the bumper cap 30 and the cylinder 10. The inner cylindrical surface 37 of the tubular portion 36 is formed with multiple ("four" in this embodiment) stopper portions 41 (projections) that protrude radially inward of the tubular portion 36. The multiple stopper portions 41 are arranged at equal intervals in the circumferential direction of the inner cylindrical surface 37.

[0014] The stopper portion 41 has a guide surface 42 formed in an elliptical shape extending in the circumferential direction of the inner cylindrical surface 37 (the "left-right direction" in FIG. 1) when viewed from the front (see FIG. 1). The guide surface 42 forms a curved surface (a part of the cylindrical surface) that matches a cylindrical surface coaxial with the inner cylindrical surface 37. The circumferential length of the stopper portion 41 (guide surface 42) is set so that it can pass between the adjacent protrusions 21, 21 of the cylinder 10 in the process of inserting the one axial end 11 of the cylinder 10 into the tube portion 36 of the bumper cap 30.

[0015] The fit between the guide surface 42 of the stopper portion 41 and the outer peripheral surface 14 of the cylinder 10 is set so that the diameter of the tube portion 36 is not expanded and no play occurs between the bumper cap 30 and the cylinder 10. An end face 43 (receiving surface) of the stopper portion 41 on one axial end side of the bumper cap 30 (the "upper side" in FIG. 1) is disposed on a plane that includes the receiving surface 24 of the protruding portion 21 among the planes perpendicular to the axis of the cylinder 10 with the abutting surface 33 of the bumper cap 30 abutting against the outer peripheral edge portion 13 of the cylinder 10.

[0016] Next, a method for manufacturing the shock absorber 1 according to the first embodiment will be described. Here, a procedure for attaching the bumper cap 30 to one axial end 11 of the cylinder 10 will be described with reference to the flow chart shown in FIG. First, the cylinder 10 is fixed to a fixing jig (not shown) ("Step 1" in FIG. 4). While being fixed to the fixing jig, the cylinder 10 is held in an upright position.

[0017] Next, the piston rod 3 is inserted through the hole 32 in the bottom 31 of the bumper cap 30, and the other axial end 38 of the bumper cap 30 is placed over the one axial end 11 of the cylinder 10 ("Step 2" in FIG. 4). At this time, the bumper cap 30 is aligned in the rotation direction about the axis L so that the protruding portion 21 of the cylinder 10 and the stopper portion 41 of the bumper cap 30 do not overlap when viewed from the axial direction of the cylinder 10.

[0018] Next, as shown in FIG. 5, the bumper cap 30 is moved toward the other axial end side of the cylinder 10 (the "downward side" in FIG. 5) ("Step 3" in FIG. 4). During this movement, the stopper portion 41 of the bumper cap 30 passes between the adjacent protrusions 21, 21 of the cylinder 10. Then, as shown in FIG. 6, when the abutment surface 33 of the bumper cap 30 abuts against the outer peripheral edge portion 13 of the one axial end 11 of the cylinder 10, the stopper portion 41 is disposed on the other axial end side of the cylinder 10 relative to the protrusion 21 ("Step 4" in FIG. 4). At this time, the end surface 43 of the stopper portion 41 is disposed on a plane including the receiving surface 24 of the protrusion 21.

[0019] Next, the bumper cap 30 is rotated clockwise or counterclockwise around the axis L of the cylinder 10, so that the end faces 43 of the stopper portions 41 of the bumper cap 30 come into contact with the receiving faces 24 of the protrusions 21 of the cylinder 10 as shown in Fig. 7 ("Step 5" in Fig. 4). This completes the attachment of the bumper cap 30 to the cylinder 10.

[0020] Here, with a conventional bumper cap, if the interference with the cylinder is increased in order to ensure the removal load, there is a risk of cracking during installation. In contrast, in the first embodiment, a protrusion 21 that protrudes radially outward is formed on one axial end 11 of the cylinder 10, and on the other hand, a stopper portion 41 that protrudes radially inward is formed on the tubular portion 36 of the bumper cap 30, and the end face 43 on one axial end side of the stopper portion 41 is configured to abut against a receiving surface 24 on the other axial end side of the protrusion 21. According to the first embodiment, the end face 43 of the stopper portion 41 is received by the receiving surface 24 of the protrusion 21, so that the removal load of the bumper cap 30 can be secured and the bumper cap 30 can be prevented from cracking.

[0021] Second embodiment Next, a second embodiment will be described with reference to FIG. In addition, the same names and symbols are used for the parts common to the first embodiment, and duplicated explanations will be omitted.

[0022] In the first embodiment, the end face 43 on one axial end side of the oval stopper portion 41 formed on the bumper cap 30 is abutted against the receiving surface 24 on the other axial end side of the rectangular (square) protrusion portion 21 formed on the cylinder 10, thereby preventing the bumper cap 30 from coming loose from the cylinder 10.

[0023] In contrast, in the second embodiment, the axial end 11 of the cylinder 10 forms a protruding portion 21 that protrudes radially outward and has a circular guide surface 22, while the tube portion 36 of the bumper cap 30 forms a stopper portion 41 that protrudes radially outward and has a gap 51 in the circumferential direction of the inner cylindrical surface 37. In the second embodiment, corners 52, 52 at one axial end side ("upper side" in FIG. 8) of the stopper portion 41 that face each other across the gap 51 are abutted against an end portion 53 at the other axial end side ("lower side" in FIG. 8) of the protruding portion 21, in other words, the bumper cap 30 is configured to be prevented from coming off the cylinder 10 by receiving the protruding portion 21 on both sides of the gap 51 of the stopper portion 41.

[0024] According to the second embodiment, it is possible to obtain the same advantageous effects as those of the first embodiment described above. In addition, in the second embodiment, by changing the circumferential length of the gap 51 of the stopper portion 41, the load that passes axially through the gap 51 as the protrusion 21 pushes open the gap 51 of the stopper portion 41, i.e., the pull-out load of the bumper cap 30 against the cylinder 10, can be adjusted. In the second embodiment, the guide surface 42 of the protrusion 21 has a circular shape, but as shown in FIG. 9, it may have a rectangular shape that is elongated in the axial direction of the cylinder 10 (the "up-down direction" in FIG. 9).

[0025] Third embodiment Next, a third embodiment will be described with reference to FIG. 10 or FIG. In addition, the same names and symbols are used for the parts common to the first embodiment, and duplicated explanations will be omitted.

[0026] The cylinder 10 has a plurality of protrusions 21 (four in the third embodiment) whose protrusion height gradually increases from an end face 26 on the other circumferential end side (the "left side" in FIG. 10) of the cylinder 10 toward an end face 25 on one circumferential end side (the "right side" in FIG. 10). The protrusions 21 have a sliding surface 61 consisting of a flat surface formed in a rectangular shape when viewed from the front. The sliding surface 61 is disposed parallel to the axis L of the cylinder 10. A wedge-shaped claw portion 64 is formed at the corner between the sliding surface 61 and the end face 26 of the protrusions 21.

[0027] The bumper cap 30 has a plurality of stepped portions 65 (three steps in the third embodiment) whose protruding height gradually increases from an end face 62 on one circumferential end side (the "right side" in FIG. 10) of the bumper cap 30 toward an end face 63 on the other circumferential end side (the "left side" in FIG. 10). Each stepped portion 65 has an end face 66 disposed on the axial plane of the bumper cap 30 and an inclined surface 67 capable of surface contact with the sliding surface 61 of the protruding portion 21 of the cylinder 10.

[0028] Next, a procedure for attaching the bumper cap 30 to one axial end 11 of the cylinder 10 will be described. For convenience, the steps 65 formed on the stopper portion 41 will be referred to as a first step 65, a second step 65, and a third step 65 in order from one circumferential end side of the bumper cap 30 (the "right side" in FIG. 10).

[0029] First, the cylinder 10 is fixed to a fixing jig (not shown). Next, the other axial end 38 of the bumper cap 30 is placed over the one axial end 11 of the cylinder 10. At this time, the bumper cap 30 is aligned in the rotational direction so that the protrusion 21 of the cylinder 10 and the stopper portion 41 of the bumper cap 30 do not overlap when viewed in the axial direction of the cylinder 10.

[0030] Next, the bumper cap 30 is moved in the axial direction, and the abutting surface 33 of the bumper cap 30 is abutted against the outer peripheral edge portion 13 of the one axial end portion 11 of the cylinder 10. In this state, the stopper portion 41 of the bumper cap 30 is disposed between the adjacent protrusions 21, 21 of the cylinder 10. In other words, the stopper portion 41 of the bumper cap 30 is located at the same height in the axial direction as the protrusions 21 of the cylinder 10. Next, the bumper cap 30 is rotated counterclockwise around the axis L (to the "right side" in FIG. 10).

[0031] When the bumper cap 30 is rotated, the first step 65 of the stopper portion 41 passes the claw portion 64 of the protruding portion 21, and then the inclined surface 67 of the second step 65 comes into contact with the sliding surface 61 of the protruding portion 21. Then, the second step 65 is pressed radially outward (the "downward" side in FIG. 10) by the protruding portion 21, so that the claw portion 64 of the protruding portion 21 passes the second step 65. At this point, as shown in FIG. 11, the claw portion 64 of the protruding portion 21 fits into a valley portion 68 formed between an end face 66 of the second step 65 of the stopper portion 41 and the inclined surface 67 of the third step 65, thereby preventing the bumper cap 30 from coming off the cylinder 10.

[0032] According to the third embodiment, it is possible to obtain the same advantageous effects as those of the first embodiment described above. In addition, in the third embodiment, the wedge-shaped claw portion 64 of the protrusion 21 of the cylinder 10 fits into the valley portion 68 formed between adjacent step portions 65, 65 of the stopper portion 41, so that the bumper cap 30 can be reliably prevented from coming loose from the cylinder 10 without ultimately positioning the bumper cap 30 in the rotational direction relative to the cylinder 10.

[0033] (Fourth embodiment) Next, a fourth embodiment will be described with reference to FIGS. In addition, the same names and symbols are used for the parts common to the first embodiment, and duplicated explanations will be omitted.

[0034] In the first embodiment, the bumper cap 30 is positioned relative to the cylinder 10 in the axial direction of the cylinder 10 by abutting an annular abutment surface 33 formed on the bottom 31 of the bumper cap 30 against the outer peripheral edge portion 13 of one axial end portion 11 of the cylinder 10.

[0035] In contrast, in the fourth embodiment, a cylindrical spacer 71 is interposed between the abutting surface 33 of the bumper cap 30 and the outer peripheral edge portion 13 of one axial end portion 11 of the cylinder 10 as necessary, so that the bumper cap 30 is positioned relative to the cylinder 10 in the axial direction of the cylinder 10. In the fourth embodiment, the cylinder 10 has a plurality of (four in the fourth embodiment) protrusions 21A (first protrusions) arranged at equal intervals in the circumferential direction, and a plurality of (four in the fourth embodiment) protrusions 21B (second protrusions) arranged offset by an equal distance toward one axial end side (upper side in FIG. 12) from each of the protrusions 21A.

[0036] Next, a procedure for attaching the bumper cap 30 to the axial end 11 of the cylinder 10 will be described. First, the cylinder 10 is fixed to a fixing jig (not shown). Next, the other axial end 38 of the bumper cap 30 is placed over the one axial end 11 of the cylinder 10. At this time, the bumper cap 30 is aligned in the rotational direction so that the protrusions 21A and 21B of the cylinder 10 do not overlap with the stopper portion 41 of the bumper cap 30 when viewed in the axial direction of the cylinder 10.

[0037] Next, the bumper cap 30 is moved in the axial direction. During this movement, the stopper portion 41 of the bumper cap 30 passes between adjacent protrusions 21B, 21B and between adjacent protrusions 21A, 21A of the cylinder 10. Then, as shown in Fig. 13, when the abutment surface 33 of the bumper cap 30 abuts against the outer peripheral edge portion 13 of the one axial end portion 11 of the cylinder 10, the stopper portion 41 is disposed on the other axial end side of the cylinder 10 (the "lower side" in Fig. 13) with respect to the protrusion 21A.

[0038] Next, the bumper cap 30 is rotated clockwise or counterclockwise about the axis L, so that each stopper portion 41 of the bumper cap 30 comes into contact with each protrusion portion 21A of the cylinder 10, as shown in Fig. 13. This completes the attachment of the bumper cap 30 to the cylinder 10.

[0039] On the other hand, when the spacer 71 is used, the spacer 71 is fitted into the inner cylindrical surface 37 of the tube portion 36 of the bumper cap 30. The spacer 71 is positioned in the axial direction (the "upper direction" in FIG. 12) with respect to the bumper cap 30 by having an end face 73 on one axial end side (the "upper side" in FIG. 12) abut against the abutment surface 33 of the bottom portion 31 of the bumper cap 30. Note that the outer peripheral surface 72 of the spacer 71 is formed with a plurality of ("four" in the fourth embodiment) grooves (not shown) extending in the axial direction for allowing the stopper portion 41 to pass through when the spacer 71 is inserted into the tube portion 36 of the bumper cap 30.

[0040] Next, the bumper cap 30 with the spacer 71 attached thereto is placed over the one axial end 11 of the cylinder 10. Next, the bumper cap 30 is moved in the axial direction. During this movement, the stopper portion 41 of the bumper cap 30 passes between the adjacent protrusions 21B, 21B of the cylinder 10. Then, as shown in FIG. 12, when an end face 74 on the other axial end side of the spacer 71 (the "lower side" in FIG. 12) hits the outer circumferential edge portion 13 of the one axial end 11 of the cylinder 10, the stopper portion 41 is disposed on the other axial end side of the cylinder 10 with respect to the protrusion 21B.

[0041] Next, the bumper cap 30 is rotated clockwise or counterclockwise around the axis L of the cylinder 10, so that each stopper portion 41 of the bumper cap 30 comes into contact with each protrusion 21B of the cylinder 10, as shown in Fig. 12. This completes the attachment of the bumper cap 30 to the cylinder 10.

[0042] According to the fourth embodiment, it is possible to obtain the same advantageous effects as those of the first embodiment described above. In addition, in the fourth embodiment, by using the spacer 71, the axial length of the one axial end 11 of the cylinder 10 can be increased, and the stroke length of the piston rod 3 can be shortened without changing the overall length of the shock absorber 1. In other words, in the fourth embodiment, one shock absorber 1 can be adapted to different stroke lengths.

[0043] Fifth embodiment Next, a fifth embodiment will be described with reference to FIG. In addition, the same names and symbols are used for the parts common to the first embodiment, and duplicated explanations will be omitted. In the first embodiment, a stopper portion 41 protruding radially inward is formed on the inner cylindrical surface 37 of the tubular portion 36 of the bumper cap 30, and the stopper portion 41 is adapted to abut against the protrusion 21 formed on the cylinder 10.

[0044] In contrast, in the fifth embodiment, the stopper portion 41 is configured by an inverted L-shaped groove formed in the inner cylindrical surface 37 of the tube portion 36 of the bumper cap 30. The stopper portion 41 has a first groove portion 81 extending from an end face 39 (opening end) on the other axial end side (the "lower side" in FIG. 14) toward the bottom portion 31 toward one axial end side (the "upper side" in FIG. 14), and a second groove portion 82 extending from an end portion on the one axial end side of the first groove portion 81 in the circumferential direction of the tube portion 36 (the "rightward direction" in FIG. 14). A plurality of stopper portions 41 ("four" in the fifth embodiment) are formed at intervals in the circumferential direction of the tube portion 36.

[0045] Next, a procedure for attaching the bumper cap 30 to the axial end 11 of the cylinder 10 will be described. First, the cylinder 10 is fixed to a fixing jig (not shown). Next, the other axial end 38 of the bumper cap 30 is placed over the one axial end 11 of the cylinder 10 so that each protrusion 21 of the cylinder 10 is inserted into the first groove 81 of each stopper portion 41 of the bumper cap 30.

[0046] Next, the bumper cap 30 is moved toward the other axial end side (the "downward" side in FIG. 14) until the protruding portion 21 abuts against an end face 83 on the one axial end side (the "upper" side in FIG. 14) of the stopper portion 41. Next, as shown in FIG. 14, the bumper cap 30 is rotated clockwise about the axis L until the protruding portion 21 abuts against an end face 84 on the circumferential tip side (the "right side" in FIG. 14) of the second groove portion 82 of the stopper portion 41. This completes the attachment of the bumper cap 30 to the cylinder 10.

[0047] According to the fifth embodiment, it is possible to obtain the same advantageous effects as those of the first embodiment described above. In addition, in the fifth embodiment, the stopper portion 41 can be aligned in the rotational direction relative to the protrusion 21 by rotating the bumper cap 30 until the protrusion 21 abuts the end face 84 of the stopper portion 41 (second groove portion 82), making it easy to position the bumper cap 30 in the rotational direction relative to the cylinder 10.

[0048] In the first, second, and fourth embodiments described above, the bumper cap 30 needs to be rotated relative to the cylinder 10 so that each stopper portion 41 of the bumper cap 30 is aligned and abutted against each protrusion 21 of the cylinder 10.

[0049] In the above-described embodiment, a rotation jig 91 (see FIG. 15) that rotates the bumper cap 30 by a predetermined angle can be used. In this case, a plurality of (e.g., four) protrusions 98 that protrude radially outward are formed on the cylindrical portion 36 of the bumper cap 30. The plurality of protrusions 98 are formed in a cylindrical shape and are disposed at equal intervals in the circumferential direction.

[0050] On the other hand, the rotating jig 91 has a cylindrical tube portion 92 and a guide portion 93 that protrudes radially inward from an inner cylindrical surface (reference number omitted) of the tube portion 92. The guide portion 93 is formed with a guide surface 94 (inclined surface) that extends in the circumferential direction of the inner cylindrical surface of the tube portion 92. The guide surface 94 is formed so that when the protrusion 98 of the bumper cap 30 moves a distance X in the circumferential direction ("rightward" in FIG. 15) along the guide surface 94, the protrusion 98 moves a distance Y toward one axial end side ("upward" in FIG. 15).

[0051] Next, a procedure for rotating the bumper cap 30 using the rotating jig 91 will be described. First, the other axial end 38 of the bumper cap 30 is placed over the one axial end 11 of the cylinder 10. At this time, the bumper cap 30 is aligned in the rotational direction so that the protrusion 21 of the cylinder 10 and the stopper portion 41 of the bumper cap 30 do not overlap when viewed in the axial direction of the cylinder 10.

[0052] Next, the bumper cap 30 is moved in the axial direction until the abutment surface 33 of the bottom portion 31 of the bumper cap 30 abuts against the outer peripheral edge portion 13 of the one axial end portion 11 of the cylinder 10 (see FIG. 6). As a result, the stopper portion 41 is disposed on the other axial end side relative to the protrusion portion 21 (see FIG. 6). Next, the bumper cap 30 is covered with a rotating jig 91, and the guide surfaces 94 of the guide portions 93 of the rotating jig 91 are brought into contact with the protrusions 98 of the bumper cap 30.

[0053] Next, the rotating jig 91 is moved a distance Y toward the other axial end side ("downward" in FIG. 15) relative to the bumper cap 30. As a result, the protrusion 98 slides along the guide surface 94 of the guide portion 93 while moving a distance X in the circumferential direction ("rightward" in FIG. 15), and the bumper cap 30 rotates a predetermined angle relative to the cylinder 10. As a result, each stopper portion 41 of the bumper cap 30 comes into contact with each protrusion 21 of the cylinder 10 (see FIG. 7), and the attachment of the bumper cap 30 to the cylinder 10 is completed. [Explanation of symbols]

[0054] 1 shock absorber, 3 piston rod, 10 cylinder, 11 axial end portion, 21 protrusion portion, 30 bumper cap, 31 bottom portion, 32 hole, 36 tube portion, 41 stopper portion

Claims

1. A cylinder in which a working fluid is sealed; A piston rod protruding from one axial end of the cylinder; a bottomed cylindrical bumper cap attached to one axial end of the cylinder and having a bottom portion formed with a hole through which the piston rod is inserted and a cylindrical portion covering an outer periphery of the cylinder; A shock absorber comprising: a protrusion formed at one axial end of the cylinder and protruding radially outward from a side wall of the cylinder; a stopper portion formed on a radially inner side of the cylindrical portion and abutting against the protruding portion; A shock absorber comprising:

2. 2. The shock absorber according to claim 1, The stopper portion has a protrusion portion that receives the protrusion in the axial direction of the cylinder.

3. 2. The shock absorber according to claim 1, A shock absorber characterized in that the stopper portion has a first groove portion extending in the axial direction of the cylindrical portion from the opening end of the cylindrical portion toward the bottom side of the cylindrical portion, and a second groove portion extending in the circumferential direction of the cylindrical portion from the first groove portion.

4. 2. The shock absorber according to claim 1, The stopper portion has a stepped portion formed in a plurality of steps in a circumferential direction of the cylindrical portion, A shock absorber, characterized in that the protruding height of each of the plurality of stepped portions increases successively from one circumferential end side to the other circumferential end side of the cylindrical portion.

5. 2. The shock absorber according to claim 1, a spacer interposed between one axial end of the cylinder and a bottom of the bumper cap; A shock absorber, wherein the protrusion includes a first protrusion and a second protrusion provided axially with a space therebetween from the first protrusion.

6. A cylinder in which a working fluid is sealed; A piston rod protruding from one axial end of the cylinder; a bottomed cylindrical bumper cap attached to one axial end of the cylinder and having a bottom portion formed with a hole through which the piston rod is inserted, a cylindrical portion covering an outer periphery of the cylinder, and a stopper portion formed on a radially inner side of the cylindrical portion and abutting against the protrusion; A method for manufacturing a shock absorber comprising: Fixing the cylinder to a fixture; moving the bumper cap in an axial direction relative to the cylinder so that the stopper portion is disposed on the other axial end side of the cylinder relative to the protrusion; rotating the bumper cap so that the stopper portion comes into contact with the protruding portion; A method for manufacturing a shock absorber, comprising:

7. A cylinder in which a working fluid is sealed; A piston rod protruding from one axial end of the cylinder; a bottomed cylindrical bumper cap attached to one axial end of the cylinder and having a bottom portion formed with a hole through which the piston rod is inserted, a cylindrical portion having a protrusion protruding radially outward and covering an outer periphery of the cylinder, and a stopper portion formed radially inward of the cylindrical portion and abutting against the protrusion; A method for manufacturing a shock absorber comprising: Fixing the cylinder to a fixture; moving the bumper cap in an axial direction relative to the cylinder so that the stopper portion is disposed on the other axial end side of the cylinder relative to the protrusion; abutting an inclined surface formed on a rotating jig against the protrusion; a step of rotating the bumper cap by moving the protrusion along the inclined surface during the process of moving the rotating jig in the axial direction of the cylinder; abutting the stopper portion on the protruding portion; A method for manufacturing a shock absorber, comprising:

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