JP7584366B2 - Welding parts and shock absorbers - Google Patents

Description

The present invention relates to a welded component and a shock absorber.

Some shock absorbers have a bump rubber attached to the part of the piston rod that extends from the cylinder (see, for example, Patent Document 1).

JP 2017-180561 A

There is a need to prevent deterioration of durability in shock absorbers.

Therefore, the present invention aims to provide a welded member that can prevent a decrease in the durability of surrounding components, and a shock absorber that can prevent a decrease in durability.

In order to achieve the above object, the first aspect of the present invention is a welded member joined by welding, comprising a first member having a first protrusion tapered toward a tapered tip, a second member arranged to face the first protrusion of the first member and having a second protrusion tapered toward the first protrusion, and a welded portion protruding from the first protrusion and the second protrusion toward the outer periphery by welding the first protrusion of the first member to the second protrusion of the second member, and the first member or the second member is provided with a hollow cover portion that prevents the welded portion from protruding beyond the outer periphery of the first member or the second member.

The second aspect of the present invention is a shock absorber having a cylinder filled with a working fluid and closed at one end, a piston slidably disposed within the cylinder, a piston rod connected to the piston and extending outside the cylinder, a closing member closing the other end of the cylinder, and an elastic member attached to the piston rod extending outside the cylinder, the piston rod having a first member tapered toward the end, a second member disposed opposite the first member and tapered toward the first member, and a welded portion protruding from the first member and the second member toward the outer periphery by welding the tip of the first member to the tip of the second member, and the first member or the second member is provided with a hollow cover portion that prevents the welded portion from protruding beyond the outer periphery of the first member or the second member.

The present invention makes it possible to provide a welded member that can suppress the deterioration of the durability of surrounding components, and a shock absorber that can suppress the deterioration of durability.

1 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention. 1 is a schematic cross-sectional view showing a main part of a shock absorber according to a first embodiment of the present invention; FIG. 6 is a schematic cross-sectional view of a main portion of a shock absorber according to a second embodiment of the present invention. FIG. 11 is a schematic cross-sectional view of a main portion of a shock absorber according to a third embodiment of the present invention.

[First embodiment]
The first embodiment will be described below with reference to FIGS.
FIG. 1 shows a shock absorber 11 of a first embodiment. This shock absorber 11 is used in a suspension system of a vehicle such as an automobile or a railroad car. Specifically, the shock absorber 11 is used in a suspension system of an automobile. The shock absorber 11 is a double-tube shock absorber equipped with a cylinder 17 having an inner tube 15 and an outer tube 16. The inner tube 15 is cylindrical. The outer tube 16 is a bottomed tube having a larger diameter than the inner tube 15. The outer tube 16 is provided radially outside the inner tube 15 and coaxially with the inner tube 15. A reservoir chamber 18 is formed between the outer tube 16 and the inner tube 15.

The outer cylinder 16 has a body member 20 and a bottom member 21. The body member 20 is a stepped cylinder whose axial middle portion has a larger diameter than both axial portions. The bottom member 21 is fitted and fixed to one axial end of the body member 20. The fitting portion of the bottom member 21 with the body member 20 and the body member 20 constitute the cylindrical body portion 22 of the outer cylinder 16. The body portion 22 is stepped. The portion radially inward of the fitting portion of the bottom member 21 with the body member 20 constitutes the bottom portion 23 of the outer cylinder 16. The bottom portion 23 closes one axial end of the body portion 22. The end of the body portion 22 opposite to the bottom portion 23 is an opening portion 24. The opening portion 24 of the outer cylinder 16 is also provided at one axial end of the cylinder 17. The bottom portion 23 of the outer cylinder 16 is also provided at the other axial end of the cylinder 17. In other words, one axial end of the cylinder 17 is the opening 24, and the other axial end is the bottom 23.

A mounting eye (not shown) is fixed to the side of the bottom 23 opposite the opening 24. The mounting eye is connected to the wheel side of the vehicle. A spring seat 25 is attached to the outer periphery of the body 22. The spring seat 25 receives the lower end of a spring (not shown) that supports the vehicle body. The inner cylinder 15 is a one-piece molded product made of a single piece of metal and is cylindrical.

The shock absorber 11 includes a valve body 27 and a rod guide 28 (a blocking member). The valve body 27 is annular and is provided at one axial end of the inner cylinder 15 and the outer cylinder 16. The rod guide 28 is annular and is provided at the other axial end of the inner cylinder 15 and the outer cylinder 16. The valve body 27 constitutes the base valve 30, and has a stepped outer periphery. The valve body 27 is placed on the bottom 23. At that time, the valve body 27 is positioned radially relative to the outer cylinder 16 at the large diameter portion of the outer periphery.

The rod guide 28 is made of metal and has a circular ring shape. The outer periphery of the rod guide 28 is stepped, with a large diameter portion and a smaller diameter portion. The large diameter portion of the outer periphery of the rod guide 28 fits into the inner periphery of the barrel 22 of the outer cylinder 16 on the opening 24 side.

One axial end of the inner cylinder 15 is fitted into the small diameter portion of the outer periphery of the valve body 27. The other axial end of the inner cylinder 15 is fitted into the small diameter portion of the outer periphery of the rod guide 28. In this state, the inner cylinder 15 is positioned axially and radially with respect to the outer cylinder 16. Here, the space between the valve body 27 and the bottom 23 is in communication with the inner cylinder 15 and the outer cylinder 16 via a passage groove 40 formed in the valve body 27. The space between the valve body 27 and the bottom 23 constitutes a reservoir chamber 18, as does the space between the inner cylinder 15 and the outer cylinder 16.

The shock absorber 11 is provided with an annular rod seal 41 (blocking member). The rod seal 41 is provided on the opposite side of the bottom 23 of the rod guide 28. This rod seal 41 is also fitted to the inner periphery of the body 22, similar to the rod guide 28. An engagement portion 43 is formed on the end of the body 22 opposite the bottom 23. The engagement portion 43 is formed by plastically deforming the body member 20 radially inward by crimping processing such as curling. The rod seal 41 is sandwiched between the engagement portion 43 and the rod guide 28. At that time, the rod seal 41 is pressed against the inner periphery of the body 22 by the rod guide 28. As a result, the rod seal 41 blocks the opening 24 of the outer cylinder 16. In other words, the rod guide 28 and the rod seal 41 block the opening 24 at the end of the cylinder 17. The rod seal 41 is specifically an oil seal.

The shock absorber 11 is provided with a piston 45. The piston 45 is slidably provided in the cylinder 17. The piston 45 is slidably provided in the inner tube 15 of the cylinder 17. The piston 45 divides the inner tube 15 into two chambers, a first chamber 48 and a second chamber 49. The first chamber 48 is provided between the piston 45 and the rod guide 28 in the inner tube 15. The second chamber 49 is provided between the piston 45 and the valve body 27 in the inner tube 15. The second chamber 49 is divided from the reservoir chamber 18 by the valve body 27. In the cylinder 17, the first chamber 48 and the second chamber 49 are filled with oil liquid L as a working fluid. In the cylinder 17, the reservoir chamber 18 is filled with gas G and oil liquid L as a working fluid.

The shock absorber 11 is equipped with a piston rod 51 (welded member). One axial end of the piston rod 51 is inserted into the cylinder 17. This one end is connected to the piston 45. The other axial end of the piston rod 51 extends to the outside of the cylinder 17 through the opening 24 of the outer tube 16. The piston rod 51 is made of metal and passes through the first chamber 48. The piston rod 51 does not pass through the second chamber 49. Therefore, the first chamber 48 is a rod side chamber through which the piston rod 51 passes. The second chamber 49 is a bottom side chamber on the bottom 23 side of the cylinder 17. The piston rod 51 is connected to the vehicle body at the part extending from the cylinder 17 to the outside.

The piston rod 51 has a rod main body 101 (second member) and an attachment member 102 (first member). The piston rod 51 is formed by joining the rod main body 101 and the attachment member 102 by welding.
The rod main body 101 has a main shaft portion 111 and a mounting shaft portion 112. The mounting shaft portion 112 has an outer diameter smaller than that of the main shaft portion 111. The main shaft portion 111 has an outer peripheral surface 111a in a cylindrical surface shape. The mounting shaft portion 112 side of the piston rod 51 is inserted into the cylinder 17. The piston 45 is fixed to the mounting shaft portion 112 of the piston rod 51 by a nut 54. The piston rod 51 extends from the cylinder 17 to the outside through the rod guide 28 and the rod seal 41 at the main shaft portion 111. The rod guide 28 and the rod seal 41 are provided on the side of the cylinder 17 from which the piston rod 51 extends. The rod guide 28 slidably supports the piston rod 51. The piston rod 51 is guided by the rod guide 28 at the outer peripheral surface 111a of the main shaft portion 111. The piston rod 51 moves axially together with the piston 45 relative to the cylinder 17. During the extension stroke of the shock absorber 11, in which the piston rod 51 increases the amount of protrusion from the cylinder 17, the piston 45 moves toward the first chamber 48. During the compression stroke of the shock absorber 11, in which the piston rod 51 decreases the amount of protrusion from the cylinder 17, the piston 45 moves toward the second chamber 49.

The rod seal 41 is provided on the side where the piston rod 51 of the cylinder 17 extends, i.e., on the opening 24 side of the outer tube 16. The rod seal 41 is pressed against the body 22 of the outer tube 16 by the rod guide 28, making tight contact. The rod seal 41 and the rod guide 28 seal between the body 22 of the outer tube 16 and the main shaft portion 111 of the piston rod 51, preventing the oil liquid L in the inner tube 15 and the gas G and oil liquid L in the reservoir chamber 18 from leaking to the outside. The rod seal 41 and the rod guide 28 close one end of the cylinder 17, the other end of which is closed by the bottom 23.

The piston 45 is formed with a passage 55 and a passage 56. Both the passage 55 and the passage 56 pass through the piston 45 in the axial direction. The passages 55 and 56 can communicate with the first chamber 48 and the second chamber 49. The shock absorber 11 is provided with a disk valve 57 and a disk valve 58. The disk valve 57 is provided on the opposite side of the piston 45 from the bottom 23 in the axial direction. The disk valve 57 is annular and closes the passage 55 by abutting against the piston 45. The disk valve 58 is provided on the bottom 23 side of the piston 45 in the axial direction. The disk valve 58 is annular and closes the passage 56 by abutting against the piston 45. The disk valves 57 and 58 are attached to the piston rod 51 together with the piston 45 by a nut 54.

The piston rod 51 moves to the contraction side, increasing the amount of penetration into the inner tube 15 and the outer tube 16, and the piston 45 moves in the direction of narrowing the second chamber 49. As a result, when the pressure in the second chamber 49 becomes higher than the pressure in the first chamber 48 by a predetermined value or more, the disc valve 57 opens the passage 55 to allow the oil L in the second chamber 49 to flow into the first chamber 48. At that time, the disc valve 57 generates a damping force. The piston rod 51 moves to the extension side, increasing the amount of protrusion from the inner tube 15 and the outer tube 16, and the piston 45 moves in the direction of narrowing the first chamber 48. As a result, when the pressure in the first chamber 48 becomes higher than the pressure in the second chamber 49 by a predetermined value or more, the disc valve 58 opens the passage 56 to allow the oil L in the first chamber 48 to flow into the second chamber 49. At that time, the disc valve 58 generates a damping force.

At least one of the piston 45 and the disk valve 57 has a fixed orifice (not shown). This fixed orifice allows the first chamber 48 to communicate with the second chamber 49 through the passage 55 even when the disk valve 57 is in the most blocked state of the passage 55. At least one of the piston 45 and the disk valve 58 has a fixed orifice (not shown). This fixed orifice allows the first chamber 48 to communicate with the second chamber 49 through the passage 56 even when the disk valve 58 is in the most blocked state of the passage 56.

The valve body 27 is formed with a liquid passage 61 and a liquid passage 62. Both the liquid passage 61 and the liquid passage 62 pass through the valve body 27 in the axial direction. Both the liquid passages 61 and 62 can communicate between the second chamber 49 and the reservoir chamber 18. The base valve 30 includes a disk valve 65 and a disk valve 66. The disk valve 65 is provided on the bottom 23 side of the valve body 27 in the axial direction. The disk valve 65 closes the liquid passage 61 by abutting against the valve body 27. The disk valve 66 is provided on the opposite side of the valve body 27 from the bottom 23 in the axial direction. The disk valve 66 closes the liquid passage 62 by abutting against the valve body 27. The base valve 30 has a pin 68. This pin 68 attaches the disk valves 65 and 66 to the valve body 27. The valve body 27, the disk valves 65 and 66, the pin 68, and the like constitute the base valve 30.

The piston rod 51 moves toward the contraction side, and the piston 45 moves in a direction narrowing the second chamber 49. As a result, when the pressure in the second chamber 49 becomes higher than the pressure in the reservoir chamber 18 by a predetermined value or more, the base valve 30 opens the disk valve 65 and the fluid passage 61 to allow the oil L in the second chamber 49 to flow into the reservoir chamber 18. At that time, the disk valve 65 generates a damping force. When the piston rod 51 moves toward the extension side and the piston 45 moves toward the first chamber 48, the pressure in the second chamber 49 drops below the pressure in the reservoir chamber 18. Then, the base valve 30 opens the disk valve 66 and the fluid passage 62 to allow the oil L in the reservoir chamber 18 to flow into the second chamber 49. The disk valve 66 is a suction valve that allows the oil L to flow from the reservoir chamber 18 into the second chamber 49 without generating any substantial damping force.

The shock absorber 11 includes a locking ring 77, a stopper member 78, a first elastic member 81, and a second elastic member 82.
An annular engagement groove 85 is formed in the main shaft portion 111 of the piston rod 51. The engagement groove 85 is recessed radially inward from the outer circumferential surface 111a of the main shaft portion 111. The engagement groove 85 is formed in a portion of the main shaft portion 111 that is disposed within the inner cylinder 15 and is disposed between the piston 45 and the rod guide 28.
The locking ring 77 is made of metal and has a C-shape with a portion of the ring cut out. The locking ring 77 is fitted into the engagement groove 85. This restricts the axial movement of the locking ring 77 relative to the piston rod 51.
The stopper member 78 is made of metal and has an annular shape. The main shaft portion 111 of the piston rod 51 and the locking ring 77 are disposed radially inside the stopper member 78. In this state, the portion of the stopper member 78 that is on the piston 45 side in the axial direction of the piston rod 51 is crimped radially inward and plastically deformed. Then, the stopper member 78 is fixed to the piston rod 51 by the locking ring 77 while restricting the radial expansion of the locking ring 77.
The first elastic member 81 and the second elastic member 82 are both annular. The first elastic member 81 abuts against the stopper member 78 on the side opposite the piston 45 with the piston rod 51 fitted inside. The second elastic member 82 abuts against the first elastic member 81 on the side opposite the piston 45 with the piston rod 51 fitted inside.
The stopper member 78, the first elastic member 81 and the second elastic member 82 move integrally with the piston rod 51, and when the piston rod 51 is positioned at a predetermined position on the fully extended side, the second elastic member 82 abuts against the rod guide 28. This causes the first elastic member 81 and the second elastic member 82 to elastically deform and absorb impact.

The shock absorber 11 has a bump rubber 71 (elastic member) supported by the piston rod 51. The bump rubber 71 is a peripheral member provided around the piston rod 51. The bump rubber 71 is made of rubber and is cylindrical. The bump rubber 71 is attached to a portion of the piston rod 51 that extends outward from the cylinder 17. The piston rod 51 is inserted into the radial inside of the bump rubber 71. As a result, the bump rubber 71 is supported by the piston rod 51. An end 72 of the bump rubber 71 on the rod seal 41 side in the axial direction of the piston rod 51 abuts against the rod seal 41. An end 73 of the bump rubber 71 on the opposite side to the rod seal 41 in the axial direction of the piston rod 51 abuts against the vehicle body when the piston rod 51 moves toward the contraction side.

As described above, the piston rod 51 is formed by joining the rod body 101 and the mounting member 102 by welding. The rod body 101 has a main shaft portion 111, a mounting shaft portion 112, and a main body side protrusion 121 (second protrusion). The rod body 101 is made of steel. The main body side protrusion 121 protrudes in the opposite direction to the mounting shaft portion 112 from the end edge of the main shaft portion 111 on the opposite side to the mounting shaft portion 112 in the axial direction of the rod body 101.

2, the body-side protrusion 121 is inclined so that the outer diameter becomes smaller the further away from the main shaft portion 111 in the axial direction of the rod body 101. The outer peripheral surface 121a of the body-side protrusion 121 is tapered so that the diameter becomes smaller the further away from the main shaft portion 111 in the axial direction of the rod body 101. In other words, the body-side protrusion 121 is inclined so that the tip surface 121b side at the end opposite the main shaft portion 111 in the axial direction of the rod body 101 becomes thinner. In further words, the body-side protrusion 121 protrudes from the main shaft portion 111 in a tapered shape with a tapered tip that is inclined so that the tip becomes thinner. The body-side protrusion 121 is the tip of the rod body 101 on the mounting member 102 side.

As shown in FIG. 1, the mounting member 102 has a disk-shaped portion 131, a screw shaft portion 132, and an engagement portion 133. As shown in FIG. 2, the mounting member 102 has a cover portion 134 and a member-side protrusion portion 135 (first protrusion portion). The mounting member 102 is made of steel. As shown in FIG. 1, the disk-shaped portion 131 has an outer peripheral surface 131a that is cylindrical. The screw shaft portion 132 has a male thread 138 formed on its outer peripheral portion. The engagement portion 133 is formed in a hexagonal column shape. The engagement portion 133 is a portion that engages with a tool. The outer diameter of the disk-shaped portion 131 is larger than the maximum outer diameter of the screw shaft portion 132. The maximum outer diameter of the screw shaft portion 132 is larger than the maximum outer diameter of the engagement portion 133. The mounting member 102 is a bolt member having a male thread 138.

2, the cover portion 134 is annular and coaxial with the disc-shaped portion 131. In other words, the cover portion 134 is hollow. The cover portion 134 protrudes from the outer peripheral edge of the end of the disc-shaped portion 131 opposite the screw shaft portion 132 to the opposite side of the screw shaft portion 132 in the axial direction of the mounting member 102. The outer peripheral surface 134a of the cover portion 134 is cylindrical. The outer peripheral surface 134a of the cover portion 134 coincides with the central axis of the outer peripheral surface 131a of the disc-shaped portion 131 and has the same diameter. Therefore, the outer peripheral surfaces 131a and 134a are continuous. The diameters of the outer peripheral surfaces 131a and 134a of the mounting member 102 are larger than the diameter of the outer peripheral surface 111a of the main shaft portion 111. The diameter of the outer peripheral surfaces 131a, 134a of the mounting member 102 is the largest in the mounting member 102 and is also the largest in the piston rod 51. The inner peripheral surface 134b of the cover portion 134 is a tapered surface that increases in diameter as it moves away from the disk-shaped portion 131 in the axial direction of the mounting member 102. The tip surface 134c of the cover portion 134 on the opposite side to the disk-shaped portion 131 in the axial direction of the mounting member 102 is flat and extends perpendicular to the central axis of the mounting member 102.

The member-side protrusion 135 is located radially inside the cover portion 134 and protrudes from the disk-shaped portion 131 to the same side as the cover portion 134. The member-side protrusion 135 has an outer diameter smaller than the inner diameter of the cover portion 134. The member-side protrusion 135 is inclined in the axial direction of the mounting member 102 so that the outer diameter becomes smaller as it moves away from the disk-shaped portion 131. The member-side protrusion 135 has an outer peripheral surface 135a that is a tapered surface that becomes smaller in diameter as it moves away from the disk-shaped portion 131 in the axial direction of the mounting member 102. In other words, the member-side protrusion 135 is inclined so that the tip surface 135b side at the end opposite the disk-shaped portion 131 in the axial direction of the mounting member 102 becomes thinner. In other words, the member-side protrusion 135 protrudes from the disk-shaped portion 131 in a tapered shape that is inclined so that the tip becomes thinner. The cover portion 134 and the member-side protrusion portion 135 are the tip portion of the mounting member 102 on the rod body 101 side.

With the central axis of the mounting member 102 aligned with that of the rod body 101, the tip surface 135b of the component-side protrusion 135 is abutted against the tip surface 121b of the body-side protrusion 121 of the rod body 101. Then, the tip surface 135b of the component-side protrusion 135 of the mounting member 102 and the tip surface 121b of the body-side protrusion 121 of the rod body 101 are welded and joined together. This forms the piston rod 51.

In this joined state, the piston rod 51 has a rod body 101, an attachment member 102, and a welded portion 141, which is a so-called weld burr. In addition, in this joined state, the member-side protrusion 135 of the attachment member 102 is inclined so that the tip becomes narrower toward the tip surface 135b, which is one end face of the attachment member 102. In addition, in this joined state, the body-side protrusion 121 of the rod body 101 is arranged to face the tip surface 135b of the member-side protrusion 135 of the attachment member 102. In addition, in this joined state, the body-side protrusion 121, which is the tip of the tip surface 121b side of the rod body 101, is inclined so that it becomes narrower toward the tip surface 135b of the member-side protrusion 135, which is the tip of the attachment member 102. In addition, in this joined state, the welded portion 141 spreads outward from the tip surface 135b of the member-side protrusion 135, which is the tip of the mounting member 102, and the tip surface 121b of the body-side protrusion 121, which is the tip of the rod body 101. In other words, the welded portion 141 protrudes outward from the member-side protrusion 135 and the body-side protrusion 121. In addition, in this joined state, the mounting member 102 has a hollow cover portion 134 so as to cover the member-side protrusion 135 on the outer periphery side. In addition, in this joined state, the cover portion 134 is formed such that the inner circumference is equal to or smaller than the outer circumference of the rod body 101. That is, the maximum diameter φ1 of the inner periphery surface 134b of the cover portion 134 is equal to or smaller than the diameter φ2 of the outer periphery surface 111a of the main shaft portion 111 of the rod body 101. It is more preferable that the maximum diameter φ1 of the inner circumferential surface 134b of the cover portion 134 is smaller than the diameter φ2 of the outer circumferential surface 111a of the main shaft portion 111 of the rod body 101.

As described above, the mounting member 102 is provided with a hollow cover portion 134 that covers the member-side protrusion 135 on the outer periphery. Therefore, this cover portion 134 prevents the welded portion 141, which is generated when welding the rod main body 101 and the mounting member 102, from protruding radially outward beyond the outer periphery of the mounting member 102. In other words, the cover portion 134 prevents the welded portion 141 from protruding radially outward beyond the outer periphery surfaces 131a, 134a of the mounting member 102. Moreover, the cover portion 134 also prevents the welded portion 141 from protruding radially outward beyond the outer periphery surface 111a of the main shaft portion 111 of the rod main body 101.

The piston rod 51 is clamped to an attachment portion (not shown) of the vehicle body via an elastic mount member (not shown) by the disk-shaped portion 131 of the mounting member 102 and a nut (not shown) that is screwed into the male thread 138. This allows the piston rod 51 to be attached to the vehicle body via the mount member. As a result, a load is input to the piston rod 51 mainly in the axial direction from the vehicle body via the mount member (not shown).

As shown in FIG. 1, a bump rubber 71 is disposed on the piston rod 51 outside the rod seal 41. An end 72 of the bump rubber 71 on the rod seal 41 side abuts against the rod seal 41. When the piston rod 51 is positioned at a predetermined position on the fully retracted side, an end 73 of the bump rubber 71 opposite the rod seal 41 abuts against the vehicle body. Here, the diameter of the outer circumferential surfaces 131a, 134a of the mounting member 102, which is the maximum outer diameter of the piston rod 51, is slightly larger than the minimum inner diameter of the bump rubber 71.

The above-mentioned Patent Document 1 describes a shock absorber in which a bump rubber is provided on the portion of the piston rod that extends from the cylinder. In such shock absorbers, the piston rod may be formed by welding multiple members together. In this case, the members melt during welding, and the welded portion formed may protrude as a burr on the outer periphery of the piston rod. As a result, for example, when assembling the bump rubber, the welded portion may come into contact with the bump rubber and scratch it. This may reduce the durability of the bump rubber.

The piston rod 51, which is a welded member of the shock absorber 11 of the first embodiment, has a mounting member 102, a rod body 101, and a welded portion 141. The mounting member 102 is inclined so that the member-side protrusion 135, which is the tip of the mounting member 102, becomes thinner as it approaches the end side, i.e., the rod body 101. In other words, the mounting member 102 is inclined so that the tip becomes thinner as it approaches the end side. The rod body 101 is arranged so that the body-side protrusion 121, which is the tip of the rod body 101, faces the member-side protrusion 135 of the mounting member 102, and is inclined so that it becomes thinner toward the tip side, i.e., the member-side protrusion 135. The welded portion 141 is expanded toward the outer periphery side from the tip surface 135b of the member-side protrusion 135 of the mounting member 102 and the tip surface 121b of the body-side protrusion 121 of the rod body 101 by welding the member-side protrusion 135 of the mounting member 102 and the body-side protrusion 121 of the rod body 101. In other words, the welded portion 141 spreads outward in the radial direction from both the member-side protruding portion 135 and the body-side protruding portion 121. The mounting member 102 is provided with a hollow cover portion 134 that prevents the welded portion 141 from protruding radially outward from the outer periphery of the mounting member 102. Therefore, the welded portion 141 can be prevented from protruding radially outward from the outer periphery of the mounting member 102. Therefore, the shock absorber 11 can reduce the possibility that the welded portion 141 will come into contact with and damage the bump rubber 71 when assembling the bump rubber 71, which is a peripheral member of the piston rod 51. Therefore, the shock absorber 11 can prevent the durability of the bump rubber 71 from decreasing, and thus the durability of the shock absorber 11 from decreasing. Of course, the welded portion 141 can also be prevented from hitting the bump rubber 71 and impeding the assembly when assembling the bump rubber 71.

The cover portion 134 is provided on the mounting member 102, and its inner circumference is formed to be equal to or smaller than the outer circumference of the rod body 101. Therefore, the cover portion 134 can prevent the welded portion 141 from protruding radially outward from the outer circumference of the rod body 101. Therefore, the shock absorber 11 can further reduce the possibility that the welded portion 141 will come into contact with and damage the bump rubber 71 when assembling the bump rubber 71, which is a peripheral member of the piston rod 51. Therefore, the shock absorber 11 can further prevent the durability of the bump rubber 71 from decreasing, and thus the durability of the shock absorber 11 can further be prevented from decreasing. In addition, the welded portion 141 can further be prevented from hitting the bump rubber 71 and impeding the assembly when assembling the bump rubber 71.

Here, by providing a sufficient difference in diameter near the welded mating surface between the rod body and the mounting member, it is possible to suppress the impact on other parts even if the weld spreads radially. However, if the difference in diameter between the two is not set sufficiently, the weld may spread outward to a size greater than the outer diameter of the piston rod, which may damage the bumper rubber. In particular, it is effective to apply the structure of the shock absorber 11 of the first embodiment in such cases.

In addition, removing the welded portion that has spread outward in a later process leads to increased costs, such as increased processing man-hours and increased capital investment. The shock absorber 11 of the first embodiment can prevent increased costs by eliminating the need to remove the welded portion 141 in a later process, while suppressing the welded portion 141 from spreading out too far in the radial direction.

[Second embodiment]
Next, the second embodiment will be described with a focus on differences from the first embodiment, mainly based on Fig. 3. Note that parts common to the first embodiment will be designated by the same names and reference numerals.
In the shock absorber 11A of the second embodiment, a piston rod 51A (welded member) that is partially different from the piston rod 51 of the first embodiment is provided in place of the piston rod 51.

As shown in FIG. 3, the piston rod 51A has a mounting member 102 similar to that of the first embodiment, and a rod main body 101A (second member) that is partially different from the rod main body 101.
The rod main body 101A has a main shaft portion 111 and a mounting shaft portion 112 (see FIG. 1) similar to those in the first embodiment. The rod main body 101A has a main body side protrusion 121A (second protrusion) which is partially different from the main body side protrusion 121, and a cover portion 151A which is not present in the first embodiment.

The cover portion 151A is a circular ring shape coaxial with the main shaft portion 111. In other words, the cover portion 151A is hollow. The cover portion 151A protrudes from the outer peripheral edge of the end portion opposite the mounting shaft portion 112 (see FIG. 1) of the main shaft portion 111 in the axial direction of the rod main body 101A to the opposite side of the mounting shaft portion 112. The outer peripheral surface 151Aa of the cover portion 151A is cylindrical. The outer peripheral surface 151Aa of the cover portion 151A coincides with the central axis of the outer peripheral surface 111a of the main shaft portion 111 and has the same diameter. Therefore, the outer peripheral surfaces 151Aa and 111a are continuous. The inner peripheral surface 151Ab of the cover portion 151A is a tapered surface shape that becomes larger in diameter as it moves away from the main shaft portion 111 in the axial direction of the rod main body 101A. The cover portion 151A has a planar tip surface 151Ac on the opposite side of the main shaft portion 111 in the axial direction of the rod body 101A, which extends perpendicular to the central axis of the rod body 101A.

The body-side protrusion 121A is located radially inside the cover portion 151A and protrudes from the main shaft portion 111 to the same side as the cover portion 151A. The body-side protrusion 121A has an outer diameter equal to or smaller than the inner diameter of the cover portion 151A. The body-side protrusion 121A is inclined in the axial direction of the rod body 101A so that the outer diameter becomes smaller as it moves away from the main shaft portion 111. The body-side protrusion 121A has a tapered surface shape in which the outer peripheral surface 121Aa becomes smaller as it moves away from the main shaft portion 111 in the axial direction of the rod body 101A. In other words, the body-side protrusion 121A is inclined so that the tip surface 121Ab side at the end opposite the main shaft portion 111 in the axial direction of the rod body 101A becomes thinner. In other words, the body-side protrusion 121A protrudes from the main shaft portion 111 in a tapered shape inclined so that the tip becomes thinner. The cover portion 151A and the body side protrusion 121A are the tip portion of the rod body 101A on the mounting member 102 side. The tip surface 121Ab of the body side protrusion 121A is located on the opposite side of the main shaft portion 111 from the tip surface 151Ac of the cover portion 151A in the axial direction of the rod body 101A. Therefore, in the axial direction of the rod body 101A, the amount by which the body side protrusion 121A protrudes from the main shaft portion 111 is greater than the amount by which the cover portion 151A protrudes from the main shaft portion 111.

With the central axis of the mounting member 102 aligned with that of the rod main body 101A, the tip surface 135b of the member-side protrusion 135 is abutted against the tip surface 121Ab of the main body-side protrusion 121A of the rod main body 101A. Then, the tip surface 135b of the member-side protrusion 135 of the mounting member 102 and the tip surface 121Ab of the main body-side protrusion 121A of the rod main body 101A are welded and joined together. This forms the piston rod 51A.

In this joined state, the piston rod 51A has a rod main body 101A, a mounting member 102, and a welded portion 141A. In addition, in this joined state, the member-side protrusion 135 of the mounting member 102 is inclined so that the tip surface 135b side, which is one end face of the mounting member 102, i.e., the tip side, becomes thinner. In addition, in this joined state, the body-side protrusion 121A of the rod main body 101A is arranged to face the tip surface 135b of the member-side protrusion 135 of the mounting member 102. In addition, in this joined state, the body-side protrusion 121A, which is the tip of the tip surface 121Ab side of the rod main body 101A, is inclined so that it becomes thinner toward the tip surface 135b of the member-side protrusion 135, which is the tip of the mounting member 102. In addition, in this joined state, the welded portion 141A extends outward from the tip surface 135b of the member-side protrusion 135, which is the tip of the mounting member 102, and the tip surface 121Ab of the body-side protrusion 121A, which is the tip of the rod body 101A. In addition, in this joined state, the rod body 101A has a hollow cover portion 151A that covers the body-side protrusion 121A on the outer periphery. In addition, in this joined state, the tip surface 134c of the cover portion 134 of the mounting member 102 and the tip surface 151Ac of the cover portion 151A of the rod body 101A face each other at a distance in the axial direction of the piston rod 51A.

Here, the mounting member 102 similar to that of the first embodiment is provided with a hollow cover portion 134 so as to cover the member-side protrusion portion 135 on the outer periphery. Therefore, this cover portion 134 prevents the welded portion 141A, which is generated when the rod main body 101A and the mounting member 102 are welded, from protruding radially outward beyond the outer periphery of the mounting member 102. In other words, the cover portion 134 prevents the welded portion 141A from protruding radially outward beyond the outer periphery surfaces 131a, 134a of the mounting member 102.

The rod main body 101A is also provided with a hollow cover portion 151A that covers the outer periphery of the main body side protrusion 121A. This cover portion 151A prevents the welded portion 141A, which is generated when the rod main body 101A and the mounting member 102 are welded, from protruding radially outward beyond the outer periphery of the rod main body 101A. In other words, the cover portion 151A prevents the welded portion 141A from protruding radially outward beyond the outer periphery surfaces 111a, 151Aa of the rod main body 101A.

The piston rod 51A, which is a welded member of the shock absorber 11A of the second embodiment, has an attachment member 102, a rod body 101A, and a welded portion 141A. The attachment member 102 is inclined so that its tip, the member-side protrusion 135, becomes thinner as it approaches the end side, i.e., the rod body 101A. In other words, the attachment member 102 is inclined so that its tip becomes thinner as it approaches the end side. The rod body 101A is arranged so that its tip, the body-side protrusion 121A, faces the member-side protrusion 135 of the attachment member 102, and is inclined so that it becomes thinner toward the tip side, i.e., the member-side protrusion 135. The welded portion 141A protrudes outward from the tip surface 135b of the member-side protrusion 135 of the mounting member 102 and the tip surface 121Ab of the body-side protrusion 121A of the rod body 101A by welding the member-side protrusion 135 of the mounting member 102 and the tip surface 121Ab of the body-side protrusion 121A of the rod body 101A. In other words, the welded portion 141A protrudes outward in the radial direction from both the member-side protrusion 135 and the body-side protrusion 121A. The mounting member 102 is provided with a hollow cover portion 134 that suppresses the welded portion 141A from protruding radially outward from the outer periphery of the mounting member 102. Thus, the welded portion 141A can be suppressed from protruding radially outward from the outer periphery of the mounting member 102. The rod body 101A is also provided with a hollow cover portion 151A that suppresses the welded portion 141A from protruding radially outward from the outer periphery of the rod body 101A. This prevents the welded portion 141A from protruding radially outward beyond the outer periphery of the rod body 101A. This further reduces the possibility that the welded portion 141A will come into contact with and damage the bump rubber 71 (see FIG. 1) when assembling the peripheral member of the piston rod 51A. This therefore prevents the durability of the bump rubber 71 from decreasing, and thus prevents the durability of the shock absorber 11A from decreasing. Of course, this also further prevents the welded portion 141A from hitting the bump rubber 71 and impeding the assembly when assembling the bump rubber 71.

In the second embodiment, the cover portion 134 of the mounting member 102 can be eliminated. In this case, the cover portion 151A is provided on the rod main body 101A (first member) to prevent the welded portion 141A formed by welding with the mounting member 102 (second member) from protruding radially outward from the outer periphery of the rod main body 101A. In this case, the possibility that the welded portion 141A will damage the bump rubber 71 can be reduced. That is, the shock absorber only needs to have a hollow cover portion 134 or cover portion 151A on the mounting member 102 or rod main body 101A that prevents the welded portion 141A from protruding from the outer periphery of the mounting member 102 or rod main body 101A. Also, the shock absorber only needs to have a hollow cover portion on at least one of the mounting member 102 and the rod main body 101A that prevents the welded portion 141A from protruding from the outer periphery of at least one of the mounting member 102 and the rod main body 101A.

[Third embodiment]
Next, the third embodiment will be described with a focus on differences from the first embodiment, mainly based on Fig. 4. Note that parts common to the first embodiment will be designated by the same names and reference numerals.
In the shock absorber 11B of the third embodiment, a piston rod 51B (welded member) that is partially different from the piston rod 51 of the first embodiment is provided in place of the piston rod 51.

As shown in FIG. 4, the piston rod 51B has a rod main body 101 similar to that of the first embodiment, and an attachment member 102B (first member) that is partially different from the attachment member 102.
The mounting member 102B has a disk-shaped portion 131, a screw shaft portion 132, and an engagement portion 133 (see FIG. 1), all of which are similar to those in the first embodiment. The mounting member 102B has a cover portion 134B different from those in the first embodiment, and a member-side protrusion portion 135 similar to those in the first embodiment.

The cover portion 134B is annular and coaxial with the disc-shaped portion 131. In other words, the cover portion 134B is hollow. The cover portion 134B protrudes from the outer peripheral edge of the end of the disc-shaped portion 131 opposite the screw shaft portion 132 to the opposite side of the screw shaft portion 132 in the axial direction of the mounting member 102B. The outer peripheral surface 134Ba of the cover portion 134B is cylindrical. The outer peripheral surface 134Ba of the cover portion 134B coincides with the central axis of the outer peripheral surface 131a of the disc-shaped portion 131 and has the same diameter. Therefore, the outer peripheral surfaces 131a and 134Ba are continuous. The diameters of the outer peripheral surfaces 131a and 134Ba are the largest in the mounting member 102B and are also the largest in the piston rod 51B. The inner peripheral surface 134Bb of the cover portion 134B is a tapered surface whose diameter increases the further away from the disk-shaped portion 131 in the axial direction of the mounting member 102B. The minimum diameter of the inner peripheral surface 134Bb of the cover portion 134B is smaller than the diameter of the outer peripheral surface 111a of the main shaft portion 111 of the rod main body 101. The tip surface 134Bc of the cover portion 134B on the opposite side to the disk-shaped portion 131 in the axial direction of the mounting member 102B is flat and extends perpendicular to the central axis of the mounting member 102B.

The component-side protrusion 135 is located radially inside the cover portion 134B and protrudes from the disk-shaped portion 131 on the same side as the cover portion 134B. The outer diameter of the component-side protrusion 135 is smaller than the inner diameter of the cover portion 134B.

With the central axis of the mounting member 102B aligned with that of the rod body 101, the tip surface 135b of the component-side protrusion 135 is abutted against the tip surface 121b of the body-side protrusion 121 of the rod body 101. Then, the tip surface 135b of the component-side protrusion 135 of the mounting member 102B and the tip surface 121b of the body-side protrusion 121 of the rod body 101 are welded and joined together. This forms the piston rod 51B.

In this joined state, the piston rod 51B has a rod body 101, an attachment member 102B, and a welded portion 141B. In addition, in this joined state, the member-side protrusion 135 of the attachment member 102B is inclined so that the tip surface 135b side, which is one end face of the attachment member 102B, i.e., the tip side, becomes thinner. In addition, in this joined state, the body-side protrusion 121 of the rod body 101 is arranged to face the tip surface 135b of the member-side protrusion 135 of the attachment member 102B. In addition, in this joined state, the body-side protrusion 121, which is the tip of the tip surface 121b side of the rod body 101, is inclined so that it becomes thinner toward the tip surface 135b of the member-side protrusion 135, which is the tip of the attachment member 102B. In addition, in this joined state, the welded portion 141B extends outward from the tip surface 135b of the member-side protrusion 135, which is the tip of the mounting member 102B, and the tip surface 121b of the body-side protrusion 121, which is the tip of the rod body 101. In addition, in this joined state, the mounting member 102B has a hollow cover portion 134B that covers the member-side protrusion 135 on the outer periphery. In addition, in this joined state, the tip surface 134Bc of the cover portion 134B of the mounting member 102B protrudes toward the rod body 101 side in the axial direction of the piston rod 51B beyond the tip surface 135b of the member-side protrusion 135. In other words, the cover portion 134B of the mounting member 102B is positioned to overlap with the rod body 101 in the axial direction of the piston rod 51B.

The mounting member 102B is provided with a hollow cover portion 134B that covers the member-side protrusion 135 on the outer periphery. Moreover, this cover portion 134B protrudes toward the rod body 101 side further than the member-side protrusion 135 in the axial direction of the piston rod 51B. Therefore, this cover portion 134B further prevents the welded portion 141B, which is generated when welding the rod body 101 and the mounting member 102B, from protruding radially outward beyond the outer periphery of the mounting member 102B. In other words, the cover portion 134B prevents the welded portion 141B from protruding radially outward beyond the outer periphery 131a, 134Ba of the mounting member 102B.

The piston rod 51B, which is a welded member of the shock absorber 11B of the third embodiment, has an attachment member 102B, a rod body 101, and a welded portion 141B. The attachment member 102B is inclined so that its tip, the member-side protrusion 135, becomes thinner as it approaches the end side, i.e., the rod body 101. In other words, the attachment member 102B is inclined so that its tip becomes thinner as it approaches the end side. The rod body 101 is positioned so that its tip, the body-side protrusion 121, faces the member-side protrusion 135 of the attachment member 102B, and is inclined so that it becomes thinner toward the tip side, i.e., the member-side protrusion 135. The welded portion 141B protrudes outward from the tip surface 135b of the member-side protrusion 135 of the mounting member 102B and the tip surface 121b of the body-side protrusion 121 of the rod body 101 by welding the member-side protrusion 135 of the mounting member 102B and the tip surface 121b of the body-side protrusion 121 of the rod body 101. In other words, the welded portion 141B protrudes radially outward from both the member-side protrusion 135 and the body-side protrusion 121. The mounting member 102B is provided with a hollow cover portion 134B that prevents the welded portion 141B from protruding radially outward from the outer periphery of the mounting member 102B. Moreover, this cover portion 134B protrudes toward the rod body 101 side more than the member-side protrusion 135 in the axial direction of the piston rod 51B. Therefore, it is possible to further prevent the welded portion 141B from protruding radially outward from the outer periphery of the mounting member 102B. Therefore, the shock absorber 11B can further reduce the possibility that the welded portion 141B will come into contact with and damage the bump rubber 71 (see FIG. 1), which is a peripheral member of the piston rod 51B, when the bump rubber 71 is assembled. Therefore, the shock absorber 11B can further prevent the durability of the bump rubber 71 from decreasing, and thus the durability of the shock absorber 11 from decreasing. Of course, the welded portion 141B can also further prevent the bump rubber 71 from coming into contact with the bump rubber 71 and impeding the assembly when the bump rubber 71 is assembled.

11, 11A, 11B... shock absorber, 17... cylinder, 28... rod guide (blocking member), 41... rod seal (blocking member), 45... piston, 48... first chamber, 49... second chamber, 51, 51A, 51B... piston rod (welded member), 71... bumper rubber (elastic member), 101, 101A... rod body (second member), 102, 102B... mounting member (first member), 121, 121A... body side protrusion (second protrusion), 135... member side protrusion (first protrusion), 134, 134B, 151A... cover part.

Claims (6)

A welded member is joined by welding,
a first member having a first protruding portion tapered toward a tip;
a second member disposed to face the first protruding portion of the first member and having a second protruding portion tapered toward the first protruding portion;
a weld portion that protrudes from the first protruding portion and the second protruding portion to an outer circumferential side by welding the first protruding portion of the first member and the second protruding portion of the second member;
having
A welded member, characterized in that the first member or the second member is provided with a hollow cover portion that prevents the welded portion from protruding beyond an outer periphery of the first member or the second member. The welded member according to claim 1,
The cover portion is provided on the first member,
The cover portion is a welded member having an inner periphery that is equal to or smaller than the outer periphery of the second member. The welded member according to claim 1 or 2,
The cover portion is provided on the first member,
The cover portion is a welded member that protrudes toward the second member further than the first protruding portion of the first member. A cylinder in which a working fluid is sealed and one end is closed;
A piston slidably disposed within the cylinder;
a piston rod connected to the piston and extending to the outside of the cylinder;
a closing member that closes the other end of the cylinder;
an elastic member attached to the piston rod extending outside the cylinder,
the piston rod has a first member whose tip is tapered toward the end, a second member disposed opposite the first member and whose tip is tapered toward the first member, and a weld portion that protrudes outward from the first member and the second member by welding the tip of the first member to the tip of the second member,
A shock absorber, characterized in that the first member or the second member is provided with a hollow cover portion that prevents the welded portion from protruding beyond the outer periphery of the first member or the second member. The shock absorber according to claim 4,
The cover portion is provided on the first member,
The cover portion has an inner periphery that is equal to or smaller than the outer periphery of the second member. The shock absorber according to claim 4 or 5,
The cover portion is provided on the first member,
The cover portion protrudes toward the second member further than the tip of the first member.

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