JP6609499B2 - Bumper cap and cylinder device - Google Patents

Description

  The present invention relates to a bumper cap and a cylinder device.

  There is a cover member in which a plurality of radially extending protrusions and an annular protrusion covering an opening through which a piston rod passes are formed in the contact portion that contacts the bump rubber (see, for example, Patent Document 1).

JP 2013-177935 A

  Bump rubber may enter the gap between the bumper cap and the rod.

  Therefore, an object of the present invention is to provide a bumper cap and a cylinder device that can suppress the possibility that the bump rubber enters the gap with the rod.

  In order to achieve the above object, the bumper cap of the present invention has a circumferential rib extending in the circumferential direction at the peripheral portion on the insertion hole side on the bump rubber side of the cover portion, and extends radially outward from the circumferential rib. A plurality of radial ribs are formed, and the circumferential rib protrudes from all the radial ribs to the side opposite to the cylinder.

  Further, the cylinder device of the present invention includes a circumferential rib extending in the circumferential direction at the peripheral edge on the insertion hole side on the bump rubber side of the cover portion of the bumper cap, and a plurality of radially extending ribs extending from the circumferential rib. Radial ribs are formed, and the circumferential ribs protrude beyond all the radial ribs up to the opposite side of the cylinder.

  According to the present invention, in the bumper cap, the possibility that the bump rubber enters the gap with the rod can be kept low.

It is sectional drawing which shows the cylinder apparatus which concerns on one Embodiment of this invention. It is a partial expanded sectional view of an important section showing a cylinder device concerning one embodiment of the present invention. It is a perspective view which shows the bumper cap which concerns on one Embodiment of this invention.

  An embodiment of the present invention will be described below with reference to the drawings. A cylinder device 1 according to this embodiment shown in FIG. 1 is a shock absorber used for a suspension device of a vehicle such as an automobile or a railway vehicle. The cylinder device 1 includes a cylinder device body 2, a bumper cap 3, and a bump rubber 4. The cylinder device main body 2 includes a cylindrical metal inner cylinder 12 in which a working liquid is sealed, and a working liquid and an inner cylinder 12 that are larger in diameter than the inner cylinder 12 and provided on the outer peripheral side of the inner cylinder 12. It has a bottomed cylindrical metal outer cylinder 14 that forms a reservoir chamber 13 in which working gas is enclosed. That is, the cylinder device 1 is a double cylinder type shock absorber in which the outer cylinder 14 and the inner cylinder 12 constitute the cylinder 15.

  The outer cylinder 14 includes a cylindrical side wall portion 17 and a bottom portion 18 that closes one end side of the side wall portion 17 in the axial direction. The inner cylinder 12 has a cylindrical shape. The inner cylinder 12 is engaged with the bottom 18 of the outer cylinder 14 via an annular base valve 20 attached to one end in the axial direction. The inner cylinder 12 is engaged with the opening 19 side opposite to the bottom 18 of the side wall 17 of the outer cylinder 14 via an annular metal rod guide 21 attached to the other end in the axial direction. Are combined.

  The base valve 20 is placed on the bottom portion 18 of the outer cylinder 14 in a state of being fitted and fixed to the inner cylinder 12, and at that time, the base valve 20 is positioned in the radial direction. Thereby, the base valve 20 is arranged coaxially with the outer cylinder 14. The rod guide 21 is fitted to the inner cylinder 12 and the side wall portion 17 of the outer cylinder 14, so that the other end portion in the axial direction of the inner cylinder 12 is arranged coaxially with the outer cylinder 14. An annular seal member 23 is disposed on the opposite side of the bottom 18 with respect to the rod guide 21, and this seal member 23 is also fitted to the inner peripheral portion of the side wall 17 on the opening 19 side. Yes. The opening portion 19 of the outer cylinder 14 is also an opening portion of the cylinder 15 because it is located outside the inner cylinder 12 in the axial direction. A locking portion 24 is formed on the side opposite to the bottom portion 18 of the outer cylinder 14 by being bent radially inward, and the sealing member 23 is engaged with the locking portion 24 on the outer side in the axial direction. By being stopped, it is supported on one end side of the cylinder 15.

  A piston 25 is slidably fitted in the inner cylinder 12. The piston 25 defines a first chamber 28 and a second chamber 29 in the inner cylinder 12. The first chamber 28 is provided between the piston 25 in the inner cylinder 12 and the rod guide 21, and the second chamber 29 is provided between the piston 25 in the inner cylinder 12 and the base valve 20. The second chamber 29 in the inner cylinder 12 is defined as the reservoir chamber 13 by the base valve 20 provided on one end side of the inner cylinder 12.

  A metal rod 31 is connected to the piston 25 by a nut 32. The rod 31 has a cylindrical main shaft portion 33 having a constant outer diameter, and extends from the inner cylinder 12 and the outer cylinder 14, that is, one end side of the cylinder 15 to the outside through the rod guide 21 and the seal member 23. Yes. The rod 31 is slidably inserted inside the rod guide 21 and the seal member 23 at the main shaft portion 33. One end of the rod 31 is disposed in the outer cylinder 14 and the inner cylinder 12, and the other end is disposed outside the outer cylinder 14 and the inner cylinder 12. The rod 31 moves in the axial direction integrally with the piston 25. The seal member 23 through which the main shaft portion 33 of the rod 31 is inserted closes the space between the outer cylinder 14 and the rod 31 so that the working liquid in the inner cylinder 12 and the working gas and working liquid in the reservoir chamber 13 are external. To prevent leakage.

  A passage 34 and a passage 35 penetrating in the axial direction are formed in the piston 25. The passages 34 and 35 can communicate with the first chamber 28 and the second chamber 29. The piston 25 is provided with an annular disk valve 36 that can close the passage 34 by contacting the piston 25 on the side opposite to the bottom 18 in the axial direction. The piston 25 is provided with an annular disk valve 37 on the bottom 18 side in the axial direction that can close the passage 35 by contacting the piston 25.

  In the disc valve 36, the rod 31 moves to the contraction side to increase the amount of entry into the inner cylinder 12 and the outer cylinder 14, and the piston 25 moves in a direction to narrow the second chamber 29, so that the pressure in the second chamber 29 is the first. When the pressure is higher than the pressure in the chamber 28 by a predetermined value or more, the passage 34 is opened, and a damping force is generated at that time. In the disc valve 37, the rod 31 moves to the extending side to increase the amount of protrusion from the inner cylinder 12 and the outer cylinder 14, and the piston 25 moves in the direction of narrowing the first chamber 28, so that the pressure in the first chamber 28 becomes the second chamber. When the pressure becomes higher than the pressure 29 by a predetermined value or more, the passage 35 is opened, and a damping force is generated at that time.

  A passage 41 and a passage 42 penetrating in the axial direction are formed in the base valve 20. The passages 41 and 42 can communicate the second chamber 29 and the reservoir chamber 13. The base valve 20 is provided with an annular disc valve 43 that can close the passage 41 by contacting the base valve 20 on the side of the bottom 18 in the axial direction, and on the side opposite to the bottom 18 in the axial direction. An annular disk valve 44 that can close the passage 42 by contacting the base valve 20 is disposed.

  The disc valve 43 is a check valve that allows the flow of the working liquid from the second chamber 29 to the reservoir chamber 13 side via the passage 41 and restricts the flow of the working liquid through the passage 41 in the opposite direction. The disc valve 43 opens the passage 41 when the rod 31 moves to the contraction side and the pressure in the second chamber 29 becomes higher than the pressure in the reservoir chamber 13 by a predetermined value or more. It is a valve.

  The disc valve 44 is a check valve that allows the flow of the working liquid from the reservoir chamber 13 to the second chamber 29 side through the passage 42 and restricts the flow of the working liquid through the passage 42 in the opposite direction. The disc valve 44 opens the passage 42 when the rod 31 moves to the extension side, the piston 25 moves to the first chamber 28 side, and the pressure in the second chamber 29 falls below the pressure in the reservoir chamber 13. In this case, the suction valve flows the working liquid from the reservoir chamber 13 into the second chamber 29 without substantially generating a damping force.

  A cylindrical mounting eye 46 is fixed to the outside of the bottom 18 of the outer cylinder 14. In the cylinder device body 2, a portion outside the seal member 23 of the rod 31 and an attachment eye 46 are attached to a relative movement portion to be attached. In the cylinder device body 2, the piston 25 slides in the inner cylinder 12 of the cylinder 15 in the axial direction integrally with the rod 31 by the relative movement of the portion to be attached, thereby changing the volumes of the first chamber 28 and the second chamber 29. In this case, a damping force is generated by the flow resistance of the oil generated in the piston 25 and the base valve 20. In the cylinder device body 2, for example, the rod 31 is connected to the vehicle body side of the vehicle, and the mounting eye 46 is connected to the wheel side of the vehicle to generate a damping force against the movement of the wheel relative to the vehicle body.

  As shown in FIG. 2, the rod guide 21 has a substantially stepped annular shape. A large-diameter portion 51 whose outer peripheral surface is a cylindrical surface is formed on one side in the axial direction, and the outer peripheral surface is on the other side in the axial direction. A small diameter portion 52 formed of a cylindrical surface having a smaller diameter than the outer peripheral surface of the large diameter portion 51 is formed. The large diameter portion 51 and the small diameter portion 52 are formed coaxially, and the rod guide 21 is fitted to the inner peripheral surface of the outer cylinder 14 at the large diameter portion 51, and the inner peripheral surface of the inner cylinder 12 at the small diameter portion 52. To fit.

  An annular projecting portion 55 that protrudes in the axial direction is formed at the end of the rod guide 21 on the large diameter portion 51 side in the axial direction. A communication hole 56 that penetrates the rod guide 21 along the axial direction is formed in the annular protrusion 55 at the radially inner position. The communication hole 56 is open to the reservoir chamber 13 between the outer cylinder 14 and the inner cylinder 12 on the side opposite to the annular protrusion 55 in the axial direction of the rod guide 21.

  The seal member 23 includes an integrally formed seal member body 63 in which a metal annular member 62 is embedded in a synthetic rubber seal material 61, a metal annular spring 64, and a metal annular spring 65. have. The annular member 62 is for maintaining the shape of the sealing material 61, and causes the sealing member main body 63 to have strength for fixing to the target portion. The seal member main body 63 is supported on one end side of the cylinder 15 with the position of the annular member 62 in the radial direction sandwiched between the annular convex portion 55 of the rod guide 21 and the locking portion 24 of the outer cylinder 14.

  The sealing material 61 has a dust lip portion 71, an oil lip portion 72, a seal ring portion 73, and a check lip portion 74.

  The dust lip 71 extends in a cylindrical shape from the inner peripheral surface side of the annular member 62 to one side in the axial direction. The oil lip portion 72 extends in a cylindrical shape from the inner peripheral surface side of the annular member 62 to the other side in the axial direction. The seal member main body 63 has the main shaft portion 33 of the rod 31 inserted in the oil lip portion 72 and the dust lip portion 71 so as to be slidable. The dust lip portion 71 and the oil lip portion 72 are inserted into the main shaft of the rod 31. The gap with the portion 33 is sealed.

  The seal ring portion 73 protrudes in an annular shape from the outer peripheral surface side of the annular member 62 to the same side as the oil lip portion 72 in the axial direction. The seal ring portion 73 simultaneously contacts the annular convex portion 55 of the rod guide 21 and the outer cylinder 14 to seal the gap between the outer cylinder 14 and the rod guide 21.

  The check lip 74 protrudes from an intermediate position in the radial direction of the annular member 62 in the shape of an annular cylinder on the same side as the axial oil lip 72. The check lip 74 abuts radially inward of the annular convex portion 55 of the rod guide 21, and the working fluid leaking from the gap between the rod guide 21 and the main shaft portion 33 of the rod 31 passes through the communication hole 56. The flow into the reservoir chamber 13 functions as a check valve that restricts the flow of the working fluid in the reverse direction.

  The spring 64 is attached to the outer periphery of the dust lip 71 of the seal member main body 63. The spring 65 is attached to the outer peripheral portion of the oil lip portion 72. Since the elastic dust lip 71 is fitted inside the elastic spring 64, and the cylindrical main shaft portion 33 of the rod 31 having higher rigidity than these is fitted inside the dust lip 71, this In this state, the spring 64 and the dust lip portion 71 form an annular shape following the outer peripheral shape of the main shaft portion 33 of the rod 31. Similarly, an elastic oil lip portion 72 is fitted inside the elastic spring 65, and a cylindrical main shaft portion 33 of the rod 31 having higher rigidity than these is fitted inside the oil lip portion 72. Thus, in this state, the spring 65 and the oil lip portion 72 form an annular shape following the outer peripheral shape of the main shaft portion 33 of the rod 31.

  The seal member 23 composed of the seal member main body 63 and the springs 64 and 65 has the dust lip 71 and the spring 64 outside the outer cylinder 14 through the opening 19 on the radially inner side of the locking portion 24 of the outer cylinder 14. That is, the protrusion 77 protrudes outward from the cylinder 15. The protruding portion 77 also has an annular shape following the outer peripheral shape of the main shaft portion 33 of the rod 31.

  The bumper cap 3 is attached to the cylinder 15 so as to cover the opening 19 side, and protects the cylinder device body 2. The bumper cap 3 is an integrally molded product of synthetic resin. The bumper cap 3 is a cylindrical fixing portion 81 attached to the side wall portion 17 of the outer cylinder 14 of the cylinder 15 so as to cover the outer peripheral surface thereof, and one axial end side of the fixing portion 81. And a disc-shaped cover portion 82 that covers the end of the cylinder 15 on the side from which the rod 31 protrudes. A seal member 23 is provided at the end of the cylinder 15 on the side from which the rod 31 projects, in addition to the locking portion 24 of the outer cylinder 14. And includes a protruding portion 77 protruding toward the bumper cap 3 side.

  The fixed portion 81 includes a cylindrical portion 85 and a plurality of fitting ribs 86 that protrude radially inward from the inner peripheral surface of the cylindrical portion 85. The plurality of fitting ribs 86 have a shape extending in the axial direction of the cylindrical portion 85, and a plurality of fitting ribs 86 are formed at intervals in the circumferential direction of the cylindrical portion 85, that is, in the circumferential direction of the fixed portion 81. The opening 19 side of the side wall 17 of the outer cylinder 14 is fitted inside the fitting rib 86 in the radial direction of the fixed portion 81. The diameter of the inscribed circle of the plurality of fitting ribs 86 is smaller than the outer diameter of the side wall portion 17 on the opening 19 side. Thereby, the bumper cap 3 is fixed by being fitted to the cylinder device body 2. In this state, the bumper cap 3 is disposed coaxially with respect to the opening 19 side portion of the cylinder 15 of the cylinder device body 2, the seal member 23, and the main shaft portion 33 of the rod 31.

  The cover portion 82 has a perforated disk shape in which an insertion hole 90 through which the main shaft portion 33 of the rod 31 of the cylinder device body 2 is inserted is formed in the center in the radial direction. The cover part 82 is on the side of the fixed part 81 in the axial direction and is provided with a perforated disc-shaped main body part 91 connected to the fixed part 81, and on the side opposite to the fixed part 81 in the axial direction of the main body part 91. The circumferential rib 92 extending in the circumferential direction of the insertion hole 90 at the peripheral edge on the 90 side and the axially fixed portion 81 of the main body 91 are on the opposite side from the circumferential rib 92 in the radial direction of the circumferential rib 92. As shown in FIG. 3, a plurality of radially extending ribs 93 extending outward are provided. That is, as shown in FIG. 2, a circumferential rib 92 and a plurality of radial ribs 93 are formed on the cover portion 82 on the side opposite to the seal member 23.

  On the fixed portion 81 side of the main body portion 91 in the axial direction, a flat contact surface 101 that extends radially inward from the inner peripheral surface of the fixed portion 81 and orthogonal to the central axis of the fixed portion 81, and a contact surface A taper surface 102 that inclines and extends away from the fixing portion 81 in the radial direction from the inner peripheral edge of 101 to the inner side in the radial direction, and is fixed from the inner peripheral edge of the taper surface 102 to the inner side in the radial direction. A tapered surface 103 is formed so as to be inclined and extend away from the portion 81 in the axial direction. A cylindrical surface 104 is formed from the inner peripheral edge of the tapered surface 103 so as to extend away from the fixed portion 81 in the axial direction. A groove 105 that is recessed in the axial direction of the main body 91 from the contact surface 101 is formed on the fixed portion 81 side of the main body 91 in the axial direction. The groove 105 extends in the radial direction of the main body 91.

  When the bumper cap 3 is fixed to the outer cylinder 14 by fitting the outer cylinder 14 inside the fixing portion 81, the main body portion 91 is on one end side where the rod 31 of the cylinder 15 protrudes on the contact surface 101. It abuts on the locking portion 24 of the outer cylinder 14. Therefore, in a state where the bumper cap 3 is attached to the cylinder device main body 2, the cover portion 82 including the main body portion 91 comes into contact with one end side from which the rod 31 of the cylinder 15 protrudes. In this state, the main body 91 covers the side from which the rod 31 of the cylinder 15 of the cylinder device main body 2 protrudes and the seal member 23, but the tapered surfaces 102 and 103 and the cylindrical surface 104 are axially extended from the cylinder 15. It escapes so that interference with the dust strip part 71 and the spring 64 of the seal member 23 which protrudes outward, that is, the protrusion part 77 may be avoided.

  On the opposite side of the main body portion 91 from the axial fixing portion 81 is a flat base surface 111 having a constant axial position. That is, the base surface 111 extends perpendicular to the central axis of the bumper cap 3. As shown in FIG. 3, the base surface 111 is divided by a plurality of radial ribs 93 and has an annular shape that is intermittent in the circumferential direction of the bumper cap 3.

  The circumferential rib 92 protrudes from the base surface 111 of the main body portion 91 to the side opposite to the axial fixing portion 81 and has an annular shape coaxial with the insertion hole 90. The circumferential rib 92 includes a cylindrical surface 112 on the inner peripheral side that is continuous with the cylindrical surface 104 of the main body portion 91 and the cylindrical surface 104, and a radially outward body from the axial outer end edge of the cylindrical surface 112. A flat top surface 113 extending in parallel with the base surface 111 of the portion 91, and a base surface 111 side toward the base surface 111 in the axial direction of the main body 91 from the outer peripheral edge of the top surface 113 in the radial direction. It has a tapered surface 114 that extends in an inclined manner so as to have a large diameter and is connected to the base surface 111.

  The tapered surfaces 102 and 103 and the cylindrical surface 104 of the main body 91 shown in FIG. 2 and the cylindrical surface 112 of the circumferential rib 92 continuous with the cylindrical surface 104 form an insertion hole 90. Here, the inner diameters of the cylindrical surface 104 and the cylindrical surface 112, which are the minimum inner diameters of the insertion holes 90, are larger than the maximum outer diameter of the dust strip portion 71 through which the main shaft portion 33 of the rod 31 is inserted. The main shaft portion 33 has a larger diameter than the maximum outer diameter of the spring 64 fitted into the dust lip portion 71 through which the main shaft portion 33 is inserted. Therefore, the inner diameter of the insertion hole 90 of the bumper cap 3 is larger than the outer diameter of the protruding portion 77 protruding to the bumper cap 3 side of the seal member 23.

  The plurality of radial ribs 93 all have the same shape. As shown in FIG. 3, the plurality of radial ribs 93 are arranged at an equal pitch in the circumferential direction of the bumper cap 3, and have a radial shape centering on the insertion hole 90. As shown in FIG. 2, the plurality of radial ribs 93 protrude from the base surface 111 of the main body 91 on the side opposite to the axial fixing portion 81 at a height lower than the circumferential rib 92, and the bumper cap 3. Are partially overlapped with the circumferential rib 92.

  The radial rib 93 has an outer surface opposite to the fixed portion 81 on the side opposite to the central axis 122 in the radial direction of the bumper cap 3 and the central axis in the radial direction of the bumper cap 3, that is, on the outer diameter side. The outer surface portion 123 and the inner surface portion 124 on the central axis side in the radial direction of the bumper cap 3, that is, the inner diameter side.

  As shown in FIG. 3, the intermediate surface portion 122 has a cylindrical surface shape with a central axis line in the radial direction of the bumper cap 3, and the maximum height from the base surface 111 is the entire length in the radial direction of the bumper cap 3. It is constant. The intermediate surface portion 122 becomes narrower in the circumferential direction of the bumper cap 3 as the height from the base surface 111 increases.

  The outer surface portion 123 is formed continuously with the intermediate surface portion 122 and has a spherical shape. The outer surface portion 123 has a lower height from the base surface 111 toward the outer side in the radial direction of the bumper cap 3 at a constant position in the circumferential direction of the bumper cap 3. Further, the outer surface portion 123 has a narrower width in the circumferential direction of the bumper cap 3 toward the outer side in the radial direction of the bumper cap 3, and the outer side in the circumferential direction of the bumper cap 3 at a constant position in the radial direction of the bumper cap 3. The height from the base surface 111 is reduced.

  The inward surface portion 124 is formed continuously with the intermediate surface portion 122 and is connected to the tapered surface 114 of the circumferential rib 92 in a spherical shape. The inner surface portion 124 has a lower height from the base surface 111 toward the central axis in the radial direction of the bumper cap 3 at a constant position in the circumferential direction of the bumper cap 3. Further, the inner surface portion 124 becomes narrower in the circumferential direction of the bumper cap 3 toward the central axis side in the radial direction of the bumper cap 3, and at a certain radial position of the bumper cap 3, The height from the base surface 111 decreases as the distance from the outside increases. The inward surface portion 124 is connected to the base surface 111 side with respect to the top surface 113 of the tapered surface 114 of the circumferential rib 92. The central position of the inner surface portion 124 in the circumferential direction of the bumper cap 3 and the tapered surface 114 form a concave portion 125 that is slightly recessed toward the base surface 111 in the axial direction of the bumper cap 3 as shown in FIG.

  All the radial ribs 93 have the same shape, and the height in the protruding direction from the base surface 111 is the same. Since the base surface 111 is a flat surface orthogonal to the central axis of the bumper cap 3, all the radial ribs 93 are positioned at the protruding end portions in the axial direction of the bumper cap 3. It is the same position in the axial direction.

  The circumferential ribs 92 are higher in the protruding direction from the base surface 111 than all the radial ribs 93. That is, the protruding height of the circumferential rib 92 is higher than that of all the radial ribs 93. Since the base surface 111 is a flat surface orthogonal to the central axis of the bumper cap 3, the circumferential ribs 92 are more than the radial ribs 93 to the opposite side of the cylinder 15 in the axial direction of the bumper cap 3. Is also prominent. Since the annular top surface 113 is a flat surface parallel to the base surface 111, the circumferential rib 92 protrudes from the entire radial rib 93 to the opposite side of the cylinder 15 over the entire circumference. In other words, the circumferential rib 92 is such that the position of the tip side on the protruding side in the axial direction of the bumper cap 3, that is, the position of the top surface 113, is greater than the position of the tip side on the protruding side of all the radial ribs 93. 3 is located on the opposite side of the fixed portion 81 in the axial direction. The top surface 113 of the circumferential rib 92 is the end surface of the bumper cap 3 that is located on the side opposite to the fixed portion 81 in the axial direction of the bumper cap 3. Constitutes the end of the bumper cap 3 that is on the side opposite to the cylinder 15 in the axial direction.

  In the cylinder device body 2 with the bumper cap 3 attached, for example, the rod 31 is connected to the vehicle body side, and the attachment eye 46 shown in FIG. 1 fixed to the cylinder 15 is connected to the wheel side. A bump rubber 4 made of an elastic resin material is disposed between the bumper cap 3 attached to the cylinder device body 2 and the vehicle body side. The bump rubber 4 has a cylindrical shape, and is supported on the vehicle body side with the main shaft portion 33 of the rod 31 inserted therethrough. In this state, a circumferential rib 92 and a plurality of radial ribs 93 are formed on the cover portion 82 of the bumper cap 3 on the bump rubber 4 side in the axial direction.

  In the bump rubber 4, a cylindrical fitting portion 132 for fitting the main shaft portion 33 of the rod 31 is formed in an intermediate portion in the axial direction, and the bumper cap 3 on the opposite side to the bumper cap 3 is formed on the bump rubber 4. An annular portion 133 having a radial clearance is formed between the rubber 4 and the main shaft portion 33 of the rod 31 in a state where the rubber 4 does not receive an external force in the axial direction. An annular portion 134 having a radial clearance with the main shaft portion 33 of the rod 31 is also formed on the bumper cap 3 side of the fitting portion 132 in a state where the bump rubber 4 does not receive an external force in the axial direction. Yes.

  As shown in FIG. 2, the annular portion 134 has a widened portion 141 formed on the fitting portion 132 side and a contracted portion 142 formed on the opposite side of the fitting portion 132. The expanding portion 141 extends from the fitting portion 132 toward the bumper cap 3 in the axial direction while expanding so as to expand toward the bumper cap 3 side. The contracted / closed portion 142 extends from the expanded portion 141 toward the bumper cap 3 in the axial direction so as to narrow toward the bumper cap 3 side. The minimum inner diameter of the contraction / closing portion 142 is larger than the outer diameter of the main shaft portion 33 of the rod 31, and smaller than the minimum diameter of the insertion hole 90 of the bumper cap 3, that is, the inner diameter of the cylindrical surfaces 104 and 112. . The inner diameter of the tip of the contraction / closing section 142 on the bumper cap 3 side is larger than the inner diameter of the cylindrical surface 112, that is, the inner diameter of the top surface 113.

  The cylinder device 1 generates a damping force with respect to the movement of the wheel with respect to the vehicle body by the rod 31 of the cylinder device body 2 being stroked with respect to the cylinder 15. The bump rubber 4 abuts against the cover portion 82 of the bumper cap 3 when the rod 31 strokes to the movement limit side in the contraction direction into the cylinder 15 and elastically deforms between the vehicle body side and the cylinder 15. Reduce the speed and suppress the generation of abnormal noise. At this time, in the bumper cap 3, first, the circumferential rib 92 that protrudes most on the side opposite to the cylinder 15 of the cover portion 82 first comes into contact with the contracted portion 142 of the annular portion 134 of the bump rubber 4. A plurality of radial ribs 93 abut against the bump rubber 4 to compress and deform the bump rubber 4 in the axial direction while elastically deforming the taper shape of the tapered surface 114 so that the constricted portion 142 spreads radially outward. .

  The cylinder device described in Patent Document 1 described above is a cover member in which a plurality of radially extending protrusions and an annular protrusion covering the opening through which the piston rod passes are formed in the contact portion that contacts the bump rubber. have. Since the annular protrusion has the same height as one protruding height of the line-like protrusion, there is a possibility that the bump rubber contacting the bumper cap enters the gap between the bumper cap and the rod.

  On the other hand, the bumper cap 3 of the present embodiment has bumps in contact with the bumper cap 3 because the circumferential rib 92 protrudes from the entire radial rib 93 to the opposite side of the cylinder 15 over the entire circumference. The rubber 4 is deformed so as to contact the radial rib 93 from the circumferential rib 92 over the entire circumference, and the possibility of entering the gap between the bumper cap 3 and the rod 31 can be kept low. Thereby, possibility that bump rubber 4 will contact seal member 23 can be held down low. Therefore, the possibility that the bump rubber 4 affects the seal member 23 can be kept low. The structure in which the circumferential rib 92 protrudes to the opposite side of the cylinder 15 from all the radial ribs 93 is effective for various bump rubbers, and the shape flexibility of the bump rubber is increased. Is possible.

  In the bumper cap 3, the inner diameter of the insertion hole 90 is larger than the outer diameter of the protruding portion 77 of the seal member 23. Therefore, when the bump rubber 4 enters the gap between the bumper cap 3 and the rod 31, the bump rubber 4 is highly likely to come into contact with the protruding portion 77 of the seal member 23. However, as described above, the possibility that the bump rubber 4 enters the gap between the bumper cap 3 and the rod 31 can be kept low. Is highly effective in reducing the possibility of contact with the seal member 23.

  In the above embodiment, the spherical inner surface portion 124 is formed on the radial axis side of the radial rib 93 on the bumper cap 3 in the radial direction, but this is eliminated, and the cylindrical intermediate surface portion 122 is left in the circumferential direction. The rib 92 may be extended to the tapered surface 114 and connected to the tapered surface 114.

  In the present embodiment, the example in which the synthetic resin is used as the material of the bumper cap 3 is shown, but it may be formed of steel or iron. However, the use of synthetic resin allows the circumferential ribs and radial ribs to be integrally formed with a mold, resulting in excellent productivity.

  The embodiment described above includes a cover portion that is formed with an insertion hole through which the rod of a cylinder device body having a cylinder and a rod extending from one end side of the cylinder is inserted, and is in contact with one end side of the cylinder. A bumper cap that is in contact with the bump rubber on the opposite side of the cover portion from the cylinder, the cover portion on the bump rubber side, a circumferential rib extending in the circumferential direction at a peripheral edge portion on the insertion hole side, A plurality of radial ribs extending radially outward from the circumferential rib are formed, and the circumferential rib protrudes from all the radial ribs to the side opposite to the cylinder. Thereby, the possibility that the bump rubber contacting the bumper cap enters the gap with the rod can be kept low.

  The cylinder device body includes a seal member that is supported on one end of the cylinder and allows the rod to pass therethrough, the seal member includes a protruding portion that protrudes toward the bumper cap, and the bumper cap includes: The inner diameter of the insertion hole is larger than the outer diameter of the protrusion. The possibility that the bump rubber will affect the seal member can be kept low.

DESCRIPTION OF SYMBOLS 1 Cylinder apparatus 2 Cylinder apparatus main body 3 Bumper cap 4 Bump rubber 23 Seal member 31 Rod 77 Projection part 82 Cover part 90 Insertion hole 92 Circumferential rib 93 Radial rib

Claims (3)

The cylinder device main body having a cylinder and a rod extending from one end of the cylinder is provided with a cover portion that is inserted into the rod of the cylinder device main body and is in contact with the one end side of the cylinder. Is a bumper cap whose opposite side abuts against the bump rubber,
The cover portion protrudes from the base surface toward the bump rubber side, extends in the circumferential direction radially outward of the peripheral portion of the insertion hole, and extends radially outward from the circumferential rib. A plurality of radial ribs are formed,
The circumferential rib, than all of the radial ribs projecting into the bump rubber side,
A bumper cap comprising a taper surface that is inclined so as to increase in diameter toward the base surface on an outer peripheral side of the circumferential rib . A cylinder device body having a cylinder and a rod extending from one end of the cylinder;
A bumper cap in which an insertion hole through which the rod is inserted is formed and a cover portion that comes into contact with one end side of the cylinder is provided, and a side of the cover portion opposite to the cylinder comes into contact with a bump rubber;
A cylinder device comprising:
In the cover part of the bumper cap,
A circumferential rib projecting from the base surface to the bump rubber side and extending in the circumferential direction radially outward of the peripheral edge of the insertion hole ;
A plurality of radial ribs extending radially outward from the circumferential ribs are formed;
The circumferential rib, than all of the radial ribs projecting into the bump rubber side,
A cylinder device comprising a tapered surface that is inclined so as to increase in diameter toward the base surface on an outer peripheral side of the circumferential rib . The cylinder device body has a seal member that is supported on one end side of the cylinder and allows the rod to pass through.
The sealing member is
Having a protrusion protruding toward the bumper cap,
The bumper cap is
The cylinder device according to claim 2, wherein an inner diameter of the insertion hole is larger than an outer diameter of the protruding portion.

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