Cylinder Device

Abstract

To provide a cylinder device in which a bracket can be stably fixed to an outer cylinder.SOLUTION: A cylinder device includes an inner cylinder, a piston slidably provided within the inner cylinder, an outer cylinder 16 covering an outer periphery of the inner cylinder, and a bracket 81 having a fixation part 82 fixed to an outer periphery of the outer cylinder 16 and an extension part 83 extending in a direction away from the outer cylinder 16. A radius of curvature R1 of the fixation part 82 is equal to or less than a radius of curvature R2 of the outer cylinder 16.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a cylinder device. [Background technology]

[0002] When welding a bracket to the outer cylinder of a cylinder device, projection welding is performed to reduce costs by shortening the welding time (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-124182 Summary of the Invention [Problem to be solved by the invention]

[0004] In the cylinder device, it is required to stably fix the bracket to the outer cylinder.

[0005] Therefore, an object of the present invention is to provide a cylinder device that allows a bracket to be stably fixed to an outer cylinder. [Means for solving the problem]

[0006] In order to achieve the above object, a first aspect of the present invention is configured to include an inner tube, a piston slidably arranged within the inner tube, an outer tube covering the outer periphery of the inner tube, and a bracket having a fixed portion fixed to the outer periphery of the outer tube and an extending portion extending in a direction away from the outer tube, wherein the radius of curvature of the fixed portion is equal to or less than the radius of curvature of the outer tube. [Effects of the Invention]

[0007] According to the present invention, it is possible to stably fix the bracket to the outer cylinder. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a front cross-sectional view showing a cylinder device of a first embodiment according to the present invention. [Figure 2] FIG. 1 is a partial front view showing a cylinder device of a first embodiment according to the present invention. [Figure 3] 3 is a cross-sectional view taken along the line III-III in FIG. 2, showing the outer peripheral surface of the outer cylinder and the bracket of the cylinder device of the first embodiment according to the present invention. [Figure 4] 4 is a partially enlarged view of FIG. 3 showing the outer peripheral surface of the outer cylinder and the bracket of the cylinder device of the first embodiment according to the present invention. [Figure 5] FIG. 4 is a partial front view showing a cylinder device according to a second embodiment of the present invention. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. 5, showing the outer peripheral surface of the outer cylinder and the bracket of the cylinder device of the second embodiment according to the present invention. [Figure 7] 7 is a partially enlarged view of FIG. 6 showing the outer peripheral surface of the outer cylinder and the bracket of the cylinder device of the second embodiment according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A cylinder device according to a first embodiment will be described below with reference to FIGS. FIG. 1 shows a cylinder device 11 of a first embodiment. This cylinder device 11 is a shock absorber used in a suspension device of a vehicle such as an automobile or a railway vehicle. Specifically, the cylinder device 11 is a hydraulic shock absorber used in a suspension device of an automobile. The cylinder device 11 is a twin-cylinder hydraulic shock absorber equipped with a cylinder 17 having an inner cylinder 15 and an outer cylinder 16. The inner cylinder 15 is cylindrical. The outer cylinder 16 is cylindrical with a bottom. The inner diameter of the outer cylinder 16 is larger than the outer diameter of the inner cylinder 15. The outer cylinder 16 is disposed radially outside the inner cylinder 15 and coaxially with the inner cylinder 15. In other words, the outer cylinder 16 covers the outer periphery of the inner cylinder 15. A reservoir chamber 18 is formed between the inner cylinder 15 and the outer cylinder 16.

[0010] The outer cylinder 16 has a tubular portion 21 and a bottom portion 22. The outer cylinder 16 is a one-piece molded product made of a single piece of metal. The tubular portion 21 is cylindrical. The outer peripheral surface 21a of the tubular portion 21 is a cylindrical surface. The bottom portion 22 is disk-shaped and closes one axial end of the tubular portion 21. The axial end of the tubular portion 21 opposite the bottom portion 22 forms an opening 23. The inner cylinder 15 is a cylindrical, one-piece molded product made of a single piece of metal.

[0011] The cylinder device 11 includes a valve body 25 and a rod guide 26. The valve body 25 is annular and is provided at one axial end of the inner cylinder 15 and the outer cylinder 16. The rod guide 26 is annular and is provided at the other axial end of the inner cylinder 15 and the outer cylinder 16.

[0012] The valve body 25 has a stepped outer periphery with a large diameter portion and a smaller diameter portion. The valve body 25 is placed on the bottom portion 22. At this time, the large diameter portion of the outer periphery of the valve body 25 is positioned radially relative to the bottom portion 22, i.e., the outer cylinder 16.

[0013] The rod guide 26 has a stepped outer periphery with a large diameter portion and an even smaller diameter portion. The large diameter portion of the outer periphery of the rod guide 26 fits into the inner periphery on the opening 23 side of the tubular portion 21 of the outer cylinder 16. As a result, the rod guide 26 is positioned radially relative to the tubular portion 21, i.e., the outer cylinder 16, at the large diameter portion of the outer periphery.

[0014] One axial end of the inner cylinder 15 is fitted into a small-diameter portion of the outer periphery of the valve body 25. One axial end of the inner cylinder 15 is placed on the bottom 22 of the outer cylinder 16 via the valve body 25. The other axial end of the inner cylinder 15 is fitted into a small-diameter portion of the outer periphery of a rod guide 26. The rod guide 26 is fitted into the cylindrical portion 21 of the outer cylinder 16. As a result, the inner cylinder 15 is positioned radially relative to the outer cylinder 16 via the valve body 25 and the rod guide 26. The axial space between the valve body 25 and the bottom 22 communicates with the outer cylinder 16 via a passage groove 31 formed in the valve body 25. The axial space between the valve body 25 and the bottom 22, like the space between the inner cylinder 15 and the outer cylinder 16, forms a reservoir chamber 18.

[0015] The cylinder device 11 is equipped with a seal member 35. The seal member 35 is provided on the opposite side of the rod guide 26 from the bottom portion 22 in the axial direction. This seal member 35 is annular, and is fitted to the inner periphery of the tubular portion 21, similar to the rod guide 26. A locking portion 36 is formed on the end of the tubular portion 21 opposite the bottom portion 22 in the axial direction. The locking portion 36 is formed by plastically deforming the tubular portion 21 radially inward by crimping, such as curling. The seal member 35 is sandwiched between the locking portion 36 and the rod guide 26. The opening 23 is located radially inward of the locking portion 36 of the outer cylinder 16.

[0016] The cylinder device 11 includes a piston 41. The piston 41 is provided within the inner tube 15 of the cylinder 17 so as to be slidable along the axial direction of the inner tube 15. The piston 41 divides the inner tube 15 into two chambers: a first chamber 42 and a second chamber 43. The first chamber 42 is provided between the piston 41 and the rod guide 26 within the inner tube 15. The second chamber 43 is provided between the piston 41 and the valve body 25 within the inner tube 15. The second chamber 43 is divided from a reservoir chamber 18 by the valve body 25. Within the cylinder 17, oil L as a working fluid is sealed in the first chamber 42 and the second chamber 43. Within the cylinder 17, oil L and gas G as working fluids are sealed in the reservoir chamber 18.

[0017] The cylinder device 11 is equipped with a piston rod 46. The piston rod 46 has a main shaft portion 47 and a mounting shaft portion 48. The outer diameter of the mounting shaft portion 48 is smaller than the outer diameter of the main shaft portion 47. The mounting shaft portion 48 is provided at one axial end of the piston rod 46. The mounting shaft portion 48 side of the piston rod 46 is inserted into the inner tube 15 of the cylinder 17. A piston 41 is fixed to the mounting shaft portion 48 of the piston rod 46 with a nut 51. The main shaft portion 47 of the piston rod 46 is inserted through the rod guide 26 and the seal member 35, and extends from the cylinder 17 to the outside through the opening 23.

[0018] The rod guide 26 positions the piston rod 46 in the radial direction and supports it axially slidably. The piston rod 46 is guided by sliding contact with the rod guide 26 at the main shaft portion 47. The piston rod 46 moves axially together with the piston 41 relative to the cylinder 17. During the extension stroke, in which the piston rod 46 increases the amount of protrusion from the cylinder 17, the piston 41 moves toward the first chamber 42. During the compression stroke, in which the piston rod 46 decreases the amount of protrusion from the cylinder 17, the piston 41 moves toward the second chamber 43.

[0019] The main shaft portion 47 of the piston rod 46 is in sliding contact with the inner periphery of the seal member 35. At that time, the seal member 35 closes the gap with the piston rod 46. The seal member 35 constantly seals the gap between the cylindrical portion 21 of the outer cylinder 16 and the main shaft portion 47 of the piston rod 46, and prevents the oil L in the inner cylinder 15 and the gas G and oil L in the reservoir chamber 18 from leaking to the outside.

[0020] A passage 55 and a passage 56 are formed in the piston 41. Both the passage 55 and the passage 56 pass through the piston 41 in the axial direction. Both the passages 55, 56 can communicate between the first chamber 42 and the second chamber 43. The cylinder device 11 is equipped with a disc valve 57 and a disc valve 58. The disc valve 57 is provided on the side of the piston 41 opposite the bottom 22 in the axial direction. The disc valve 57 is annular and closes the passage 55 by abutting against the piston 41. The disc valve 58 is provided on the bottom 22 side of the piston 41 in the axial direction. The disc valve 58 is annular and closes the passage 56 by abutting against the piston 41. The disc valves 57, 58 are attached to the piston rod 46 together with the piston 41.

[0021] When the piston rod 46 moves toward the compression side, increasing the amount of penetration into the inner tube 15 and the outer tube 16, and the piston 41 moves in a direction narrowing the second chamber 43, the pressure in the second chamber 43 becomes higher than the pressure in the first chamber 42. When the pressure in the second chamber 43 becomes higher than the pressure in the first chamber 42 by a predetermined value or more, the disc valve 57 opens the passage 55, allowing the oil L in the second chamber 43 to flow through the passage 55 to the first chamber 42. At this time, the disc valve 57 generates a damping force. When the piston rod 46 moves toward the extension side, increasing the amount of protrusion from the inner tube 15 and the outer tube 16, and the piston 41 moves in a direction narrowing the first chamber 42, the pressure in the first chamber 42 becomes higher than the pressure in the second chamber 43. When the pressure in the first chamber 42 becomes higher than the pressure in the second chamber 43 by a predetermined value or more, the disc valve 58 opens the passage 56, allowing the oil L in the first chamber 42 to flow through the passage 56 to the second chamber 43. At this time, the disc valve 58 generates a damping force.

[0022] A fixed orifice (not shown) is formed in at least one of the piston 41 and the disc valve 57. This fixed orifice allows communication between the first chamber 42 and the second chamber 43 via the passage 55 even when the disc valve 57 is in a state where the passage 55 is most closed by the disc valve 57. In addition, a fixed orifice (not shown) is formed in at least one of the piston 41 and the disc valve 58. This fixed orifice allows communication between the first chamber 42 and the second chamber 43 via the passage 56 even when the disc valve 58 is in a state where the passage 56 is most closed by the disc valve 58.

[0023] A passage 61 and a passage 62 are formed in the valve body 25. Both the passage 61 and the passage 62 axially penetrate the valve body 25. Both the passages 61 and 62 can communicate between the second chamber 43 and the reservoir chamber 18. The cylinder device 11 is equipped with a disc valve 65 and a disc valve 66. The disc valve 65 is provided on the opposite side of the valve body 25 from the piston 41 in the axial direction. The disc valve 65 closes the passage 61 by abutting against the valve body 25. The disc valve 66 is provided on the piston 41 side of the valve body 25 in the axial direction. The disc valve 66 closes the passage 62 by abutting against the valve body 25.

[0024] When the piston rod 46 moves toward the compression side and the piston 41 moves in a direction that narrows the second chamber 43, the pressure in the second chamber 43 becomes higher than the pressure in the reservoir chamber 18. When the pressure in the second chamber 43 becomes higher than the pressure in the reservoir chamber 18 by a predetermined value or more, the disc valve 65 opens the passage 61, allowing the hydraulic fluid L in the second chamber 43 to flow through the passage 61 into the reservoir chamber 18. At this time, the disc valve 65 generates a damping force. When the piston rod 46 moves toward the extension side and the piston 41 moves toward the first chamber 42, the pressure in the second chamber 43 becomes lower than the pressure in the reservoir chamber 18. Then, the disc valve 66 opens the passage 62, allowing the hydraulic fluid L in the reservoir chamber 18 to flow through the passage 62 into the second chamber 43. The disc valve 66 is a suction valve that allows the hydraulic fluid L to flow from the reservoir chamber 18 into the second chamber 43 without generating any substantial damping force.

[0025] In the cylinder device 11, the portion of the main shaft portion 47 of the piston rod 46 that protrudes outward in the axial direction beyond the seal member 35 is connected to the vehicle body side, and the outer cylinder 16 is connected to the wheel side of the vehicle. In this way, the cylinder device 11 damps relative vibration between the vehicle body side and the wheel side.

[0026] As shown in Fig. 2, the cylinder device 11 has a bracket 81. The bracket 81 has a fixed portion 82 and an extending portion 83. The bracket 81 is fixed to the outer periphery of the outer cylinder 16 at the fixed portion 82. In this state, the extending portion 83 extends from the fixed portion 82 in a direction away from the outer cylinder 16. The bracket 81 is formed by pressing a single plate material.

[0027] 3, the fixed portion 82 is plate-shaped and has the shape of a portion of a cylinder. The axial direction of this cylinder is the axial direction of the fixed portion 82, the circumferential direction of this cylinder is the circumferential direction of the fixed portion 82, and the radial direction of this cylinder is the radial direction of the fixed portion 82. Furthermore, the portion that forms the inner peripheral surface of this cylinder is the radial inner surface 82a of the fixed portion 82, and the portion that forms the outer peripheral surface of this cylinder is the radial outer surface 82b of the fixed portion 82. Thus, the radial inner surface 82a has the shape of a portion of the cylindrical surface.

[0028] As shown in FIG. 2, the fixing portion 82 has a first edge portion 91, a second edge portion 92, a third edge portion 93, and a fourth end portion 94 at its outer edge portions in the direction in which it extends. The first edge portion 91 is located at one axial end of the fixing portion 82 and extends in the circumferential direction of the fixing portion 82 .

[0029] The second edge portion 92 is located at the other axial end of the fixed portion 82 and includes a base portion 101 and an inclined portion 102. The base portion 101 is located on one side of the second edge portion 92 in the circumferential direction of the fixed portion 82 and extends in the circumferential direction of the fixed portion 82. The inclined portion 102 is located on the other side of the second edge portion 92 in the circumferential direction of the fixed portion 82 and is inclined with respect to the circumferential direction of the fixed portion 82. The base portion 101 is parallel to the first edge portion 91. The inclined portion 102 is inclined so that the further away from the base portion 101 in the circumferential direction of the fixed portion 82 it is, the further away from the first edge portion 91 in the axial direction of the fixed portion 82 it is.

[0030] The third edge portion 93 extends in the axial direction of the fixed portion 82 from the end of the base 101 of the second edge portion 92 opposite the inclined portion 102 in the circumferential direction of the fixed portion 82 and is connected to one end of the first edge portion 91 in the circumferential direction of the fixed portion 82. The fourth end 94 extends in the axial direction of the fixed portion 82 from the end of the inclined portion 102 of the second edge portion 92 opposite the base 101 in the circumferential direction of the fixed portion 82 and is connected to the other end of the first edge portion 91 in the circumferential direction of the fixed portion 82.

[0031] The first edge 91, the second edge 92, the third edge 93, and the fourth end 94 of the fixed portion 82 constitute a peripheral edge 111. The portion of the fixed portion 82 other than the peripheral edge 111, in other words, the portion inside the peripheral edge 111, in other words, the portion surrounded by the peripheral edge 111, constitutes an inner portion 112. In this way, the fixed portion 82 has the peripheral edge 111 and the inner portion 112 excluding the peripheral edge 111.

[0032] As shown in Figure 4, the radius of curvature R1 of the radial inner surface 82a of the fixing portion 82 is less than or equal to the radius of curvature R2 of the outer peripheral surface 21a of the tubular portion 21 of the outer tube 16, and specifically, is smaller than the radius of curvature R2 of the outer peripheral surface 21a.

[0033] 2, the extending portion 83 is connected to a fourth end portion 94 of the fixed portion 82 and extends from the fourth end portion 94. As shown in Fig. 3, the extending portion 83 is generally flat, and extends outward from the fixed portion 82 in the circumferential direction of the fixed portion 82 and also extends outward in the radial direction of the fixed portion 82.

[0034] As shown in FIG. 2, the extension portion 83 has a first edge portion 121, a second edge portion 122, and a third edge portion 123 at its outer edge portions in the direction in which it widens. The first edge portion 121 is continuous with the first edge portion 91 of the fixing portion 82 and is disposed in the same plane as the first edge portion 91 .

[0035] The second edge portion 122 has an inclined portion 125 , an intermediate portion 126 , and an inclined portion 127 . The inclined portion 125 is located on the second edge 122 closest to the fixed portion 82 , and is continuous with the inclined portion 102 of the second edge 92 of the fixed portion 82 , and is disposed on approximately the same plane as the inclined portion 102 .

[0036] The intermediate portion 126 extends in the opposite direction to the fixed portion 82 from the end of the inclined portion 125 opposite to the fixed portion 82. The intermediate portion 126 is parallel to the first edge portion 121. The inclined portion 127 extends in the opposite direction to the fixed portion 82 from the end of the intermediate portion 126 opposite to the fixed portion 82. The inclined portion 127 is inclined so that the further away from the intermediate portion 126 the inclined portion 127 is, the closer it is to the first edge portion 121 in the axial direction of the fixed portion 82.

[0037] Therefore, the portion of the fixed portion 82 and the extending portion 83 that includes the inclined portion 102 and the second edge portion 122 forms a protruding portion 131 that protrudes further than the second edge portion 92 toward the opposite side from the first edge portion 91 in the axial direction of the fixed portion 82. As a result, the extending portion 83 of the bracket 81 protrudes outward in the axial direction of the fixed portion 82 than the fixed portion 82. In other words, the fixed portion 82 of the bracket 81 is provided biased toward one side of the extending portion 83 in the axial direction of the fixed portion 82.

[0038] The third edge 123 connects the ends of the first edge 121 and the second edge 122 that are opposite the fixed portion 82. The third edge 123 extends in the axial direction of the fixed portion 82.

[0039] The extending portion 83 has a mounting hole 132 formed at a predetermined position on the inside in the direction in which the extending portion 83 widens, the mounting hole 132 penetrating the extending portion 83 in the plate thickness direction. The extending portion 83 has a recessed portion 133 formed at the first edge portion 121, recessed from the first edge portion 121 toward the second edge portion 122. The recessed portion 133 penetrates the extending portion 83 in the plate thickness direction.

[0040] Although not shown, a component to be supported is attached to the extending portion 83 of the bracket 81 by a fastener inserted into the mounting hole 132. The component to be supported is attached to the extending portion 83 of the bracket 81 by engaging with the recessed portion 133. In this way, the extending portion 83 of the bracket 81 supports the component to be supported. Note that the extending portion 83 shown in this embodiment is merely an example, and the supporting method, size, angle, etc. of the extending portion differ depending on the component to be supported, so the extending portion can have any appropriate shape.

[0041] 3, the bracket 81 is brought into an abutting state in which the radial inner surface 82a of the fixing portion 82 is abutted at a predetermined position on the outer peripheral surface 21a of the tubular portion 21 of the outer cylinder 16. At this time, the bracket 81 is arranged so that the axial direction of the fixing portion 82 is parallel to the axial direction of the tubular portion 21. Also, at this time, as shown in FIG. 2, the first end edge 91 of the bracket 81 is arranged on the bottom 22 side of the tubular portion 21 in the axial direction, and the second end edge 92 is arranged on the opposite side of the bottom 22 in the axial direction of the tubular portion 21.

[0042] 4, the radius of curvature R1 of the radial inner surface 82a of the fixed portion 82 is smaller than the radius of curvature R2 of the outer peripheral surface 21a of the tubular portion 21 of the outer cylinder 16. For this reason, the fixed portion 82 in the abutting state abutting against the outer peripheral surface 21a of the tubular portion 21 as described above is provided with a fixed portion-side abutment portion 93a at the position of the third end edge 93, which abuts in line contact with the outer peripheral surface 21a of the tubular portion 21 of the outer cylinder 16, and a fixed portion-side abutment portion 94a at the position of the fourth end 94, which abuts in line contact with the outer peripheral surface 21a of the tubular portion 21 of the outer cylinder 16. In other words, the radius of curvature R1 of the radial inner surface 82a between the fixed portion side abutment portions 93a, 94a on both sides of the fixed portion 82 in abutting state against the outer peripheral surface 21a of the tubular portion 21 is smaller than the radius of curvature R2 of the outer peripheral surface 21a between the outer tube side abutment portions on both sides that abut against the fixed portion 82 of the tubular portion 21 of the outer tube 16.

[0043] With the fixing portion 82 of the bracket 81 in this abutting state against the tubular portion 21 of the outer tube 16, a predetermined position on the inner portion 112 of the fixing portion 82 is laser welded to the tubular portion 21 from the radially outer side of the fixing portion 82. In other words, the fixing portion 82 in the abutting state is welded to the outer tube 16 from the radially opposite side of the fixing portion 82 from the outer tube 16. Here, the fixing portion 82 in the abutting state is welded at multiple locations, specifically two locations, by laser welding. As a result, as shown in FIG. 2 , multiple welds 141, specifically two welds 142 are formed at predetermined positions on the inner portion 112 of the fixing portion 82 in the abutting state. The weld 141 is located closer to the first edge portion 91 than the weld 142 in the axial direction of the fixing portion 82.

[0044] These welded portions 141, 142 are aligned with each other in the circumferential direction of the fixed portion 82 and are spaced apart from each other in the axial direction of the fixed portion 82. These welded portions 141, 142 overlap the base 101 of the second edge portion 92 and the fixed portion 82 in the circumferential direction.

[0045] These welded portions 141 and 142 are disposed at a central position between the third end edge portion 93 and the fourth end portion 94 in the circumferential direction of the fixing portion 82. In the axial direction of the fixed portion 82, the distance between the welded portion 141 on the first edge portion 91 side and the first edge portion 91 is equal to the distance between the welded portion 142 on the base portion 101 side and the base portion 101.

[0046] The arrangement of the multiple welds 141, 142 is not limited to the above, and they can be arranged in various positions. For example, the multiple welds can be aligned in the axial direction of the fixed portion 82 and spaced apart in the circumferential direction of the fixed portion 82. In this case, the multiple welds are provided at a central position between the base 101 and the first edge 91 in the axial direction of the fixed portion 82. Alternatively, there may be only one weld. In this case, the weld is provided at a central position in the circumferential direction of the fixed portion 82, that is, at a central position between the base 101 and the first edge 91 in the axial direction of the fixed portion 82.

[0047] As shown in Fig. 3, the welded portions 141 and 142 are provided at an intermediate position, specifically the central position, between the third edge portion 93 and the fourth end portion 94 in the circumferential direction of the fixed portion 82. In other words, as shown in Fig. 3, the welded portions 141 and 142 are provided at an intermediate position, specifically the central position, between the fixed portion-side contact portion 93a and the fixed portion-side contact portion 94a in the circumferential direction of the fixed portion 82.

[0048] The welded portions 141, 142 have the same shape, and as shown in Figures 3 and 4, both welded portions 141 have a convex portion 143 and a concave portion 144. The convex portion 143 protrudes radially inward from the radial inner surface 82a of the fixed portion 82 and is joined and fixed to the outer peripheral surface 21a of the tubular portion 21 by welding. The concave portion 144 is recessed radially inward from the radial outer surface 82b of the fixed portion 82. In the welded portion 141, the convex portion 143 and the concave portion 144 are aligned with each other in the circumferential direction of the fixed portion 82 and are aligned with each other in the axial direction of the fixed portion 82. The same is true for the welded portion 142.

[0049] The fixed portion 82 is in an abutting state in which the fixed portion-side abutting portion 93a and the fixed portion-side abutting portion 94a, both of which extend in the axial direction of the fixed portion 82, are in line contact with the outer peripheral surface 21a of the tubular portion 21 on both sides in the circumferential direction of the fixed portion 82. In this abutting state, the fixed portion 82 is laser-welded at a position between the fixed portion-side abutting portion 93a and the fixed portion-side abutting portion 94a in the circumferential direction of the fixed portion 82, thereby forming welds 141 and 142 shown in FIG.

[0050] In this manner, the bracket 81 in the fixed state fixed to the cylindrical portion 21 of the outer cylinder 16 by welding is in a state in which the axial direction of the fixing portion 82 is parallel to the axial direction of the cylindrical portion 21 . In addition, in this fixed state, the fixed portion 82 of the bracket 81 has the fixed portion side abutment portion 93a and the fixed portion side abutment portion 94a on both sides in the circumferential direction of the fixed portion 82 both abutting in line contact with the outer surface 21a of the tubular portion 21. 4, the fixed portion 82 of the bracket 81 in this fixed state has a gap 151 between its radial inner surface 82a and the outer peripheral surface 21a of the tubular portion 21. This gap 151 is provided in a range excluding the welded portions 141, 142, between the radial inner surface 82a between the fixed portion-side contact portions 93a and 94a in the circumferential direction of the fixed portion 82 and the outer peripheral surface 21a of the tubular portion 21 of the outer cylinder 16. This gap 151 opens on both sides from the fixed portion 82 in the axial direction of the fixed portion 82.

[0051] As shown in FIG. 1, the fixing position of the bracket 81 to the outer cylinder 16 is biased to one side in the axial direction of the outer cylinder 16, specifically, toward the bottom portion 22.

[0052] The aforementioned Patent Document 1 discloses a technology for using projection welding to reduce costs by shortening welding time when welding a bracket to the outer cylinder of a cylinder device. Projection welding requires concentrating current at the protrusions and preventing other parts from contacting the mating part to prevent current shunting. Therefore, the radius of curvature of the inner radial surface of the bracket must be larger than the radius of curvature of the outer peripheral surface of the outer cylinder. Therefore, only the protrusions, i.e., the welded part, come into contact with the outer cylinder, leaving room for improvement in terms of stably fixing the bracket to the outer cylinder.

[0053] In the cylinder device 11 of the first embodiment, the bracket 81 has a fixed portion 82 fixed to the outer periphery of the outer cylinder 16 and an extending portion 83 extending in a direction away from the outer cylinder 16, and the radius of curvature R1 of the fixed portion 82 is equal to or smaller than the radius of curvature R2 of the outer cylinder 16. Therefore, in the cylinder device 11, the fixed portion 82 of the bracket 81 can abut against the outer periphery of the outer cylinder 16 at portions other than the welded portion 141. Therefore, the cylinder device 11 can stably fix the bracket 81 to the outer cylinder 16. Specifically, in the cylinder device 11, the radius of curvature R1 of the fixed portion 82 is smaller than the radius of curvature R2 of the outer cylinder 16, so the bracket 81 abuts against the outer periphery of the outer cylinder 16 at fixed portion-side abutment portions 93a, 94a other than the welded portion 141 of the fixed portion 82. Therefore, in the cylinder device 11, the bracket 81 is supported on the outer cylinder 16 at four points: the fixed portion side abutment portions 93a, 94a and the welded portions 141, 142, and since the fixed portion side abutment portions 93a, 94a are supported by line contact, it is possible to stably fix the bracket 81 to the outer cylinder 16.

[0054] Furthermore, the cylinder device 11 allows the bracket 81 to be stably fixed to the outer cylinder 16, which makes it possible to reduce the size of the fixing portion 82. Therefore, the cost and weight of the bracket 81 can be reduced.

[0055] Furthermore, since the cylinder device 11 has the fixed portion 82 and the outer tube 16 fixed by laser welding, the radius of curvature R1 of the fixed portion 82 is smaller than the radius of curvature R2 of the outer tube 16, and even if there is a radial gap 151 between the fixed portion 82 and the outer tube 16, the fixed portion 82 can be well welded to the outer tube 16.

[0056] In addition, in the cylinder device 11, the inner portion 112 of the fixed portion 82, excluding the peripheral portion 111, is laser welded from the side opposite the outer tube 16, so that the fixed portion 82 can be easily and satisfactorily welded to the outer tube 16.

[0057] [Second embodiment] The second embodiment of the present invention will be described, focusing on differences from the first embodiment, mainly with reference to Figures 5 to 7. Note that parts common to the first embodiment will be designated by the same names and symbols.

[0058] In cylinder device 11A of the second embodiment, bracket 81, before being welded to outer cylinder 16, has the same shape as bracket 81 before being welded to outer cylinder 16 of cylinder device 11 of the first embodiment. In cylinder device 11A, bracket 81 is welded at fixing portion 82 to tubular portion 21 of outer cylinder 16 by arc welding, not laser welding.

[0059] In the cylinder device 11A, before welding, the bracket 81 is brought into contact at the fixed portion 82 with the outer peripheral surface 21a of the tubular portion 21 of the outer cylinder 16, similar to the bracket 81 of the cylinder device 11. At this time, the cylinder device 11A is in an abutting state in which the fixed portion 82 is in contact with the outer peripheral surface 21a of the tubular portion 21 at fixed portion-side abutment portions 93a and 94a on both sides in the circumferential direction of the fixed portion 82, as shown in Figures 6 and 7 .

[0060] 5, in this abutting state, the first edge portion 91 of the fixed portion 82 of the cylinder device 11A is welded to the tubular portion 21 by arc welding. At the same time, in this abutting state, the base portion 101 of the second edge portion 92 of the fixed portion 82 of the cylinder device 11A is welded to the tubular portion 21 by arc welding. As a result, in the cylinder device 11A, a weld portion 161 is formed across the first edge portion 91 and the tubular portion 21, and a weld portion 162 is formed across the base portion 101 of the second edge portion 92 and the tubular portion 21. Here, the weld portion 161 extends in a bead shape along the first edge portion 91 and is formed in a predetermined intermediate range in the extension direction of the first edge portion 91. Furthermore, the weld portion 162 extends in a bead shape along the base portion 101 of the second edge portion 92 and is formed in a predetermined intermediate range in the extension direction of the base 101.

[0061] Therefore, in the cylinder device 11A, the fixed portion 82 is joined to the outer tube 16 by arc welding the bases 101 of the first end edge portion 91 and the second end edge portion 92 shown in Figure 5, which are located in positions different from the fixed portion side abutment portion 93a and the fixed portion side abutment portion 94a shown in Figures 6 and 7.

[0062] In the cylinder device 11A, the bracket 81 in the fixed state fixed to the cylindrical portion 21 of the outer cylinder 16 by welding in this manner is in a state in which the axial direction of the fixing portion 82 is parallel to the axial direction of the cylindrical portion 21. Furthermore, in the cylinder device 11A, the fixed portion 82 of the bracket 81 in this fixed state is in a state in which the fixed portion side abutment portion 93a and the fixed portion side abutment portion 94a on both sides in the circumferential direction of the fixed portion 82 are both in line contact with the outer surface 21a of the tubular portion 21. 7, the fixed portion 82 of the bracket 81 in the fixed state has a gap 151 between its radial inner surface 82a and the outer peripheral surface 21a of the cylindrical portion 21. This gap 151 is provided between the radial inner surface 82a between the fixed portion-side abutting portions 93a and 94a in the circumferential direction of the fixed portion 82 and the outer peripheral surface 21a of the cylindrical portion 21 of the outer cylinder 16. This gap 151 opens on both sides from the fixed portion 82 in the axial direction of the fixed portion 82 in ranges on both sides outer than the welded portions 161, 162 in the circumferential direction of the fixed portion 82.

[0063] In the cylinder device 11A of the second embodiment, as in the cylinder device 11 of the first embodiment, the radius of curvature R1 of the fixing portion 82 of the bracket 81 is equal to or smaller than the radius of curvature R2 of the outer cylinder 16. Therefore, in the cylinder device 11A, the fixing portion 82 of the bracket 81 can abut against the outer periphery of the outer cylinder 16 at portions other than the welded portions 161, 162. Therefore, in the cylinder device 11A as well, the bracket 81 can be stably fixed to the outer cylinder 16. Specifically, in the cylinder device 11A as well, the radius of curvature R1 of the fixing portion 82 is smaller than the radius of curvature R2 of the outer cylinder 16, so the bracket 81 abuts against the outer periphery of the outer cylinder 16 at fixing portion-side abutment portions 93a, 94a other than the welded portions 161, 162 of the fixing portion 82. Therefore, in the cylinder device 11A, the bracket 81 is supported against the outer tube 16 at four points: the fixed portion side abutment portions 93a, 94a and the welded portions 161, 162, and further the fixed portion side abutment portions 93a, 94a are supported by line contact, and the welded portions 161, 162 are fixed in a line extending in a direction perpendicular to the fixed portion side abutment portions 93a, 94a, so that the bracket 81 can be fixed to the outer tube 16 more stably. [Explanation of symbols]

[0064] 11, 11A...cylinder device, 15...inner cylinder, 16...outer cylinder, 81...bracket, 82...fixed portion, 83...extension portion, 111...periphery portion, 112...inner portion, 141, 161, 162...welded portion, R1, R2...curvature radius.

Claims

[Claim 1] An inner cylinder, a piston slidably provided within the inner cylinder; an outer cylinder covering an outer periphery of the inner cylinder; a bracket having a fixed portion fixed to an outer periphery of the outer cylinder and an extending portion extending in a direction away from the outer cylinder; Equipped with The radius of curvature of the fixing portion is smaller than the radius of curvature of the outer cylinder, the fixing portion is in line contact with the outer cylinder at contact portions on both sides in the circumferential direction, and is fixed to the outer cylinder by laser welding from the opposite side of the outer cylinder at a plurality of points spaced apart in the axial direction at a central position between the contact portions on both sides, A cylinder device in which there are gaps that open to both axial sides of the fixed portion between the welded portion formed by the laser welding and each of the abutment portions on both sides.

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