Buffer

Abstract

To provide a shock absorber capable of achieving both prevention of cracking of a bump cap and prevention of falling of the bump cap from an outer shell.SOLUTION: A shock absorber D includes: a shock absorber body 1 having an outer shell 2 and a rod 3; a cylindrical bump cushion 10 mounted on the outer periphery of the rod 3; and a cylindrical bump cap 11 mounted on the outer periphery of the outer shell 2. The bump cap 11 has: a cylindrical part 12; a stopper part 13 that is provided at a rod side end of the cylindrical part 12 and faces the bump cushion 10; and a plurality of arc-shaped ribs 14 provided on the inner periphery of the cylindrical part 12. The plurality of ribs 14 have one or more deformation portions 15, 16, 17 having projections 15a, 16a, 17a that project from the inner periphery toward the outer shell 2 side, and recesses 15b, 15c, 16b, 16c, 17b, 17c that are on the inner periphery of the plurality of ribs 14 and are adjacent to the projections 15a, 16a, 17a.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a shock absorber.

Background Art

[0002] Conventionally, a shock absorber includes an outer shell and a rod that is inserted into and withdrawn from the outer shell freely. In addition, it includes a bump cushion provided on the rod side and a synthetic resin bump cap provided at the end of the outer shell.

[0003] In such a shock absorber, when the rod most intrudes into the outer shell at the most contracted state, the bump cushion collides with the bump cap and is compressed, and the bump cushion exerts an elastic force, thereby alleviating the impact at the most contracted state of the shock absorber.

[0004] The bump cap includes a cylindrical portion with a circular cross-section that is fitted to the outer periphery of the end of the outer shell, and an annular stopper portion provided at the top of the cylindrical portion that faces the bump cushion rubber and allows the insertion of the rod. The bump cap is fitted to the outer periphery of the end of the outer shell.

[0005] More specifically, the bump cap includes a plurality of ribs provided side by side in the circumferential direction on the inner periphery of the cylindrical portion, and the ribs are pressed against the outer periphery of the outer shell to tighten the outer shell and fix it to the outer shell (see, for example, Patent Document 1). That is, the conventional bump cap is fixed to the outer shell by press-fitting, thereby preventing it from falling off the outer shell.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] As described above, the conventional bump cap is fixed to the outer shell due to the compression of the outer shell. However, since there are errors in the height dimension of the rib provided on the inner circumference of the cylindrical portion and the dimension of the inner circumferential surface, there is a rib that strongly presses against the outer circumference of the outer shell, while there is also a rib with a weak compressive force that tightens the outer circumference of the outer shell.

[0008] As a result, the compressive force for tightening the outer shell by the bump cap varies in the circumferential direction, and the holding force for holding the outer shell by the bump cap is not stable. Therefore, the desired holding force cannot be imparted to the outer shell, and if the holding force is weak, there will be a problem that the bump cap will fall off from the outer shell.

[0009] To address this problem, if the diameter of the cylindrical portion is reduced, a large holding force can be obtained because the cylindrical portion strongly compresses the outer shell, and the fixing of the bump cap to the outer shell becomes reliable. However, if the compressive force is increased, when the bump cap is press-fitted onto the outer circumference of the end of the outer shell or when the bump cap is at a low temperature, there is a high possibility that a large stress will act on the bump cap and it will crack.

[0010] Therefore, in the conventional shock absorber, preventing the bump cap from falling off the outer shell and preventing cracking are in a trade-off relationship with each other, and it is difficult to achieve both the prevention of falling off and the prevention of cracking.

[0011] Therefore, an object of the present invention is to provide a shock absorber that can achieve both prevention of cracking of the bump cap when the bump cap is attached to the outer circumference of the end of the outer shell or when the bump cap is at a low temperature, and prevention of the bump cap from falling off the outer shell.

Means for Solving the Problems

[0012] In order to solve the above-described problems, the shock absorber of the present invention includes an outer shell, a rod axially movably inserted into the outer shell, a shock absorber body that generates a damping force when the rod moves relative to the outer shell, a cylindrical bump cushion mounted on the outer periphery of the rod, and a bump cap that is cylindrical and mounted on the outer periphery of the outer shell. The bump cap includes a cylindrical portion, an annular stopper portion provided at the rod-side end of the cylindrical portion and facing the bump cushion in the axial direction of the rod with the rod inserted through the inner peripheral side, and a plurality of ribs that are arc-shaped and arranged in the circumferential direction on the inner periphery of the cylindrical portion and whose inner periphery abuts against the outer periphery of the rod-side of the outer shell. The plurality of ribs have one or more deformed portions having a protrusion protruding from the inner periphery toward the outer shell side and a recess adjacent to the protrusion on the inner periphery of the plurality of ribs.

[0013] In the shock absorber configured as described above, when the outer shell is inserted into the cylindrical portion, the protrusion is crushed and adhered to the outer periphery of the outer shell, and the deformed protrusion escapes into the adjacent recess. Therefore, even if there is variation in the height dimension of the ribs, variation in the pressing force of each rib can be suppressed, and the holding force for holding the outer shell of the bump cap can be set as desired.

[0014] Further, the deformed portion in the bump cap of the shock absorber may have recesses on both the circumferential direction and the axial direction of the protrusion. According to the shock absorber configured as described above, even when the outer shell is inserted into the cylindrical portion and the protrusion is deformed so as to expand by compression, the deformed protrusion can be accommodated in the recess without difficulty, and the protrusion will not be caught between the inner peripheral surface of the rib and the outer peripheral surface of the outer shell to prevent close contact between the inner peripheral surface of the rib and the outer peripheral surface of the outer shell.

[0015] Furthermore, a plurality of deformation portions in the bumper cap of the shock absorber may be provided at positions shifted in the circumferential direction of the cylindrical portion with respect to one rib. According to the shock absorber configured in this way, even if the height of the rib is not uniform in the circumferential direction, the holding force for holding the outer shell of the bumper cap can be appropriately set, and both prevention of cracking of the bumper cap and prevention of dropping off from the outer shell of the bumper cap can be achieved simultaneously.

[0016] And a plurality of deformation portions in the bumper cap of the shock absorber may be provided at positions shifted in the axial direction of the cylindrical portion with respect to one rib. According to the shock absorber configured in this way, even if the outer diameter of the outer shell is not uniform in the axial direction, the holding force for holding the outer shell of the bumper cap can be appropriately set, and both prevention of cracking of the bumper cap and prevention of dropping off from the outer shell of the bumper cap can be achieved simultaneously.

[0017] Also, four or more even numbers of ribs in the bumper cap of the shock absorber are provided at equal intervals in the circumferential direction with respect to the cylindrical portion, and the deformation portions may be arranged at positions that are point-symmetrical about the center of curvature of the cylindrical portion. According to the shock absorber configured in this way, when the outer shell is inserted into the cylindrical portion, the protrusions of the deformation portions facing each other on the opposite side by 180 degrees are in close contact with each other across the outer circumference of the outer shell, so the pressing force with which each rib presses the outer shell becomes more stable.

[0018] Furthermore, the total volume of the concave portions of the deformation portions in the bumper cap may be equal to or greater than the volume in which the protrusions protrude from the inner circumferential surface of the rib. According to the shock absorber configured in this way, since it is possible to prevent the protrusions after deformation from protruding toward the outer shell side from the inner circumferential surface, even if there is a dimensional error in the height of the rib, the entire inner circumferential surface can be brought into close contact with the outer shell. Also, when the height of the rib is higher than the designed dimension, it is possible to suppress the protrusions from increasing the pressing force on the outer shell, so it is possible to more effectively achieve both prevention of cracking and prevention of dropping off of the bumper cap.

[0019] And, the concave portion of the deformed portion in the bump cap is adjacent to the protrusion in the circumferential direction of the rib, and the deformed portion may be formed over the entire length of the inner circumferential surface of the rib along the axial direction of the cylindrical portion. According to the shock absorber configured in this way, when manufacturing by injection molding in which the bump cap is molded by injecting a synthetic resin as a material into the mold, the operation of pulling out the molded bump cap from the mold in the axial direction becomes easy.

[0020] Furthermore, the protrusion of the deformed portion in the bump cap may be configured to plastically deform and be accommodated in the concave portion when the bump cap is attached to the outer periphery of the outer shell. According to the shock absorber configured in this way, when the height of the rib is lower than the designed dimension, the protrusion adheres to the outer shell to increase the tightening force of the rib, and when the height of the rib is higher than the designed dimension, the protrusion does not exhibit an excessive elastic force, so the tightening force of the rib does not become higher than that due to design errors. Therefore, it is possible to more effectively achieve both prevention of cracking and prevention of dropping of the bump cap.

Advantages of the Invention

[0021] According to the shock absorber of the present invention, it is possible to achieve both prevention of cracking of the bump cap and prevention of dropping of the bump cap from the outer shell.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0023] The present invention will be described below based on the embodiments shown in the figures. As shown in FIG. 1, a shock absorber D according to an embodiment includes a shock absorber body 1 that includes an outer shell 2 and a rod 3 and generates a damping force during expansion and contraction, a cylindrical bump cushion 10 attached to the outer periphery of the rod 3, and a bump cap 11 attached to the outer periphery of the outer shell 2. When the shock absorber body 1 contracts, the bump cap 11 and the bump cushion 10 come into contact with each other and the bump cushion 10 is compressed. Therefore, the bump cushion 10 mitigates the impact when the shock absorber D is fully contracted.

[0024] Hereinafter, each member constituting the shock absorber D will be described in detail. The shock absorber body 1 includes a bottomed cylindrical outer shell 2 and a rod 3 that is inserted into the outer shell 2 so as to be movable in the axial direction, and generates a damping force when the rod 3 moves relative to the outer shell 2. Although not shown in detail, the shock absorber body 1 includes a cylinder housed in the outer shell 2 and a piston that is connected to the rod 3 and is movably inserted into the cylinder to divide the inside of the cylinder into an extension chamber and a compression chamber. A reservoir is provided between the cylinder and the outer shell 2. Further, the extension chamber and the compression chamber are filled with liquid, and the reservoir is filled with liquid and gas. Furthermore, the shock absorber D is provided with a passage communicating the extension chamber and the compression chamber and a passage communicating the compression chamber and the reservoir, and a damping valve and a check valve for exerting a damping force are appropriately provided in these passages. The shock absorber D configured in this way exerts a damping force that resists the flow of liquid from the expanding compression chamber to the contracting extension chamber with a damping valve to prevent extension when extending. Conversely, when the shock absorber D contracts, the rod 3 enters the cylinder and the liquid is pushed out of the cylinder, and a damping force is exerted to resist the flow of liquid from the compression chamber to the reservoir with a damping valve to prevent contraction.

[0025] Further, the upper end opening end of the outer shell 2 is caulked inward, and the contents accommodated in the outer shell 2, such as a cylinder and a rod guide that pivotally supports the rod 3, are sandwiched between the caulked portion 2a at the upper end and the bottom portion at the lower end of the outer shell 2 and fixed within the outer shell 2.

[0026] As described above, the shock absorber D has been described as a double-tube shock absorber. However, the shock absorber D is not limited to a double-tube type, and any device may be used as long as it can exert a damping force when the rod 3 moves in and out of the outer shell 2. Therefore, the shock absorber D may be a single-tube (monotube) type shock absorber in which a piston is directly inserted into the outer shell 2 and an extension chamber and a compression chamber are provided within the outer shell 2. Further, the shock absorber D may be a single-rod type shock absorber or a double-rod type shock absorber. In addition to hydraulic oil, liquids such as magnetorheological fluid, electrorheological fluid, water, and aqueous solution may be used as the liquid used in the shock absorber D. When using magnetorheological fluid or electrorheological fluid, it is also possible to use a device that applies a magnetic field or an electric field to the passage instead of a damping valve.

[0027] Also, a cylindrical bump cushion 10 is attached to the outer periphery of the tip of the rod 3. As shown in FIG. 1, the bump cushion 10 is formed in a cylindrical shape with a bellows made of synthetic resin, rubber, etc., and the lower end in FIG. 1 faces the bump cap 11 in the axial direction of the rod 3. The bump cap 11 includes a cylindrical portion 12 and an annular stopper portion 13 connected to the upper end of the cylindrical portion 12 in FIG. 1, and is attached to the outer periphery of the upper end in FIG. 1, which is the rod-side end of the outer shell 2, and the stopper portion 13 faces the lower end of the bump cushion 10 in the axial direction of the rod 3. Therefore, when the rod 3 moves downward in FIG. 1 with respect to the outer shell 2, the bump cushion 10 will eventually contact the stopper portion 13 of the bump cap 11 and be compressed.

[0028] When the buffer D exhibits an extension operation in which the rod 3 moves upward in FIG. 1 with respect to the outer shell 2 due to an external force, the buffer body 1 exerts a damping force that hinders the extension. Also, when the buffer D exhibits a contraction operation in which the rod 3 moves downward in FIG. 1 with respect to the outer shell 2 due to an external force, the buffer body 1 exerts a damping force that hinders the contraction. And when the buffer D contracts until the bump cushion 10 abuts against the bump cap 11, the bump cushion 10 is compressed to generate a resilient force that hinders the contraction of the buffer D. Thus, when the buffer D contracts until the bump cushion 10 abuts against the bump cap 11, the buffer D hinders the movement of the rod 3 with respect to the outer shell 2 with the resilient force generated by the bump cushion 10 in addition to the damping force generated by the buffer body 1, thereby reducing the speed of the rod 3. Since the bump cushion 10 generates a resilient force when the buffer D contracts to near the maximum contraction, the impact at the maximum contraction can be alleviated.

[0029] Hereinafter, the bump cap 11 will be described in detail. In the present embodiment, the bump cap 11 is made of a synthetic resin. As shown in FIGS. 1 and 2, it includes a cylindrical portion 12, a stopper portion 13 that is annular and provided at the rod-side end of the cylindrical portion 12, faces the bump cushion 10 in the axial direction of the rod 3, and has the rod 3 inserted through its inner peripheral side, and a plurality of ribs 14 that are arc-shaped and arranged in the circumferential direction on the inner periphery of the cylindrical portion 12 and whose inner periphery abuts against the outer periphery of the rod-side of the outer shell 2.

[0030] The cylindrical portion 12 is cylindrical, and a plurality of ribs 14 extending in the axial direction are provided on the inner peripheral side at equal intervals in the circumferential direction. Six ribs 14 are provided on the cylindrical portion 12. As shown in FIGS. 2 and 3, the rib 14 has a cross-sectional arc shape when viewed from the axial direction of the bumper cap 11 and is provided along the axial direction of the cylindrical portion 12. Then, the bumper cap 11 is fitted to the outer periphery of the outer shell 2 by bringing the curved inner peripheral surface 14a of the rib 14 in the cylindrical portion 12 into close contact with the outer periphery of the outer shell 2 at the open end side of the outer shell 2. In addition, in order to easily insert the outer shell 2 into the bumper cap 11, a tapered surface 14b that inclines toward the inner peripheral side of the cylindrical portion 12 is provided at the lower end of the rib 14 facing the open side of the cylindrical portion 12.

[0031] In this way, when the tapered surface 14b is provided at the lower end of the rib 14 provided inside the cylindrical portion 12, when the outer shell 2 is inserted into the cylindrical portion 12, the tapered surface 14b abuts against the shoulder of the outer shell 2 and the diameter of the cylindrical portion 12 can be gradually increased. Therefore, even if the pressing force of the bumper cap 11 against the outer shell 2 is increased, the insertion operation becomes easy.

[0032] Next, the stopper portion 13 is annular and is continuous with the upper end of the cylindrical portion 12 in FIG. 2, and is provided with a plurality of thick portions 13a formed by increasing the wall thickness at equal intervals in the circumferential direction. In the present embodiment, six thick portions 13a are provided at positions overlapping the ribs 14 in the radial direction in the stopper portion 13. The number of thick portions 13a provided is arbitrary and may be provided between the ribs 14, 14 when viewed in the circumferential direction, but the number of installations is arbitrary. When the bumper cap 11 is attached to the outer shell 2, the thick portion 13a abuts against the caulking portion 2a of the outer shell 2 and positions the upper end position in FIG. 1 outside the stopper portion 13. By providing the thick portion 13a in this way, when the upper end of the stopper portion 13 in FIG. 1 abuts against the bumper cushion 10, it is possible to prevent the bumper cushion 10 from interfering with the sealing member that seals the outer periphery of the rod 3 of the shock absorber D located inside the stopper portion 13. In addition, by providing the thick portion 13a, the wall thickness of the stopper portion 13 can be partially increased, which is advantageous in terms of strength.

[0033] Furthermore, each rib 14 is provided with three deformation portions 15, 16, and 17 arranged along the circumferential direction of the rib 14. As shown in FIG. 3, the deformation portions 15, 16, and 17 each include protrusions 15a, 16a, 17a that protrude from the inner circumference toward the outer shell 2 side and recesses 15b, 15c, 16b, 16c, 17b, 17c that are adjacent to the protrusions 15a, 16a, 17a on the inner circumference of the rib 14.

[0034] The deformation portion 15 provided at the center in the circumferential direction of the rib 14 includes a protrusion 15a having an isosceles triangular cross-section and recesses 15b, 15c provided adjacent to the protrusion 15a on both sides in the circumferential direction of the protrusion 15a and both having an isosceles triangular cross-section. The protrusion 15a and the recesses 15b, 15c have a continuous cross-sectional shape along the axial direction of the cylindrical portion 12 and are provided over the entire length of the inner circumferential surface 14a of the rib 14 in the axial direction of the cylindrical portion 12. The total volume, which is the total volume of the recesses 15b, 15c recessed from the inner circumferential surface 14a of the rib 14, is equal to or greater than the volume that protrudes radially inward from the inner circumferential surface 14a of the rib 14 in the protrusion 15a.

[0035] With respect to the rib 14, the deformation portions 16 and 17 on both sides sandwiching the deformation portion 15 provided at the center in the circumferential direction have a line-symmetrical shape with respect to the normal line of the inner peripheral surface 14a of the rib 14 passing through the center of the protrusion 15a of the deformation portion 15, and include triangular protrusions 16a and 17a in cross section, and recesses 16b, 16c, 17b, and 17c provided adjacent to the protrusions 16a and 17a on both circumferential sides thereof and having a triangular cross-sectional shape. The protrusions 16a, 17a and the recesses 16b, 16c, 17b, 17c have a shape in which the cross-sectional shape is continuous along the axial direction of the cylindrical portion 12, and are provided over the entire length of the inner peripheral surface 14a in the axial direction of the cylindrical portion 12. The protrusions 16a, 17a protrude radially from the inner peripheral surface 14a of the rib 14, but protrude while being inclined in a direction away from each other toward the circumferential ends of the rib 14. The depths of the recesses 16b, 17b provided on the center side of the rib 14 with respect to the protrusions 16a, 17a are shallow, and the depths of the recesses 16c, 17c provided on the end side of the rib 14 with respect to the protrusions 16a, 17a are deeper than the recesses 16b, 17b. And the total volume of the recesses 16b, 16c recessed from the inner peripheral surface 14a of the rib 14 is equal to or greater than the volume protruding radially inward from the inner peripheral surface 14a of the rib 14 in the protrusion 16a. Also, the total volume, which is the total volume of the recesses 17b, 17c recessed from the inner peripheral surface 14a of the rib 14, is equal to or greater than the volume protruding radially inward from the inner peripheral surface 14a of the rib 14 in the protrusion 17a.

[0036] As described above, the deformed portions 15, 16, and 17 are respectively provided on each of the six ribs 14, and as shown in FIG. 3, they are arranged at point-symmetrical positions centered on the center of curvature O of the cylindrical portion 12 in the bumper cap 11. More specifically, in a cross-section obtained by cutting the cylindrical portion 12 with a plane perpendicular to the axis of the cylindrical portion 12 (a cross-section obtained by cutting the cylindrical portion 12 from the side), the deformed portions 15, 16, 17 of two ribs 14 arranged on opposite sides of the cylindrical portion 12 by 180 degrees and facing each other are arranged at point-symmetrical positions with the center of curvature O as the symmetry point. That is, the deformed portion 15 of one of the two ribs 14 arranged on opposite sides of the cylindrical portion 12 by 180 degrees and facing each other and the deformed portion 15 are arranged on opposite sides of the cylindrical portion 12 by 180 degrees and face each other, and the deformed portion 16 and the deformed portion 17 of the two ribs 14 are arranged on opposite sides of the cylindrical portion 12 by 180 degrees and face each other.

[0037] When the outer shell 2 is inserted into the cylindrical portion 12 of the bumper cap 11 configured as described above, the inner peripheral surface of the rib 14 abuts against the outer periphery of the outer shell 2, causing the diameter of the cylindrical portion 12 to expand and tightly pressing the outer periphery of the outer shell 2 via the rib 14. Then, when the outer shell 2 is inserted into the cylindrical portion 12, the deformed portions 15, 16, 17 provided on the rib 14 are crushed by the outer periphery of the outer shell 2 and deformed, being pushed into the concave portions 15b, 15c, 16b, 16c, 17b, 17c while closely adhering to the outer periphery of the outer shell 2 as shown in FIG. 4.

[0038] That is, even if there is an error in the dimensions of the rib 14, the protrusions 15a, 16a, and 17a of the deformation parts 15, 16, and 17 will surely deform and adhere closely to the outer periphery of the outer shell 2. Therefore, when the rib 14 is formed as designed, while the protrusions 15a, 16a, and 17a deform and adhere closely to the outer periphery of the outer shell 2, they are accommodated in the recesses 15b, 15c, 16b, 16c, 17b, and 17c, so that it does not prevent the inner peripheral surface 14a of the rib 14 from adhering closely to the outer periphery of the outer shell 2, and the clamping force of the rib 14 on the outer shell 2 becomes appropriate. When the rib 14 is not formed as designed and the radial height is lower than the designed dimension, although the contact surface pressure of the inner peripheral surface 14a of the rib 14 on the outer shell 2 decreases, since the protrusions 15a, 16a, and 17a adhere closely to the outer periphery of the outer shell 2, the decrease in the clamping force of the rib 14 is suppressed. When the rib 14 is not formed as designed and the radial height is higher than the designed dimension, although the contact surface pressure of the inner peripheral surface 14a of the rib 14 on the outer shell 2 increases, since the protrusions 15a, 16a, and 17a deform and are accommodated in the recesses 15b, 15c, 16b, 16c, 17b, and 17c, the protrusions 15a, 16a, and 17a do not overly clamp the outer shell 2, so the clamping force of the rib 14 is not overly increased.

[0039] In this way, the deformation parts 15, 16, and 17 adhere closely to the outer periphery of the outer shell 2 while not preventing the inner peripheral surface 14a of the rib 14 from adhering closely to the outer periphery of the outer shell 2. When the height of the rib 14 is lower than the designed dimension, the protrusions 15a, 16a, and 17a deform and adhere strongly to the outer periphery of the outer shell 2, so the decrease in the clamping force of the rib 14 is suppressed. When the height of the rib 14 is higher than the designed dimension, the protrusions 15a, 16a, and 17a escape into the recesses 15b, 15c, 16b, 16c, 17b, and 17c, so the clamping force of the rib 14 is not overly increased. Therefore, as a whole of the bump cap 11, the variation in the clamping force for clamping the outer shell 2 by each rib 14 is reduced, so that the holding force of the bump cap 11 for holding the outer shell 2 can be set as desired.

[0040] The protrusion 15a protrudes from the rib 14 in the radial direction of the cylindrical portion 12. When it is crushed by the outer periphery of the outer shell 2, it deforms and is accommodated in the recesses 15b and 15c provided on both sides of the protrusion 15a. Thus, when the protrusion 15a is protruded from the rib 14 in the radial direction of the cylindrical portion 12, since the protrusion 15a exhibits deformation such that it receives a load in the radial direction of the cylindrical portion 12 and is crushed from the apex, it is preferable to provide the recesses 15b and 15c on both sides of the protrusion 15a.

[0041] Also, the protrusions 16a (17a) protrude from the inner peripheral surface 14a of the rib 14 in an inclined manner with respect to the radial direction of the cylindrical portion 12. Among the recesses 16b, 16c (17b, 17c) on both sides of the protrusions 16a (17a), the recess 16b (17b) on the side towards which the protrusions 16a (17a) face is deeper and has a larger volume than the recess 16c (17c) on the opposite side. Since the protrusions 16a (17a) protrude in an inclined manner towards the outer shell 2 side with respect to the radial direction, when the outer shell 2 is inserted into the cylindrical portion 12, they deform so as to fall into the recess 16b (17b) having a large volume. Even when the protrusions 16a (17a) deform in this way, they can be accommodated because the volume of the recess 16b (17b) is large. The recess 16c (17c) on the opposite side facilitates the falling deformation of the protrusions 16a (17a), and is provided to accommodate the root portion after deformation because the width of the root portion becomes wider due to the deformation of the protrusions 16a (17a). In addition, when giving a direction to the deformation direction of the protrusions 16a (17a) like the deformation portion 16 (17), it may be possible to provide a recess only in the direction in which the protrusions 16a (17a) deform.

[0042] Further, the deformed portions 15(16, 17) are provided continuously over the entire length of the inner peripheral surface 14a with respect to the rib 14, but they may be provided discontinuously or may be provided on a part of the entire length of the inner peripheral surface 14a. The deformed portions 15(16, 17) are linearly provided over the entire length of the inner peripheral surface 14a with respect to the rib 14, but the protrusions 15a(16a, 17a) may be provided in a dot shape. The concave portions may be formed so as to surround the periphery of the protrusions 15a(16a, 17a). Further, different-shaped deformed portions 15, 16(17) are provided for one rib 14, but the same-shaped deformed portions 15(16, 17) may be provided for one rib 14.

[0043] As described above, the shock absorber D of the present embodiment includes a shock absorber body 1 that has an outer shell 2 and a rod 3 that is movably inserted in the outer shell 2 in the axial direction and generates a damping force when the rod 3 moves relative to the outer shell 2, a cylindrical bump cushion 10 attached to the outer periphery of the rod 3, and a bump cap 11 that is cylindrical and attached to the outer periphery of the outer shell 2. The bump cap 11 includes a cylindrical portion 12, a stopper portion 13 that is annular and provided at the rod-side end of the cylindrical portion 12, faces the bump cushion 10 in the axial direction of the rod 3, and has the rod 3 inserted through the inner peripheral side, and a plurality of ribs 14 that are arc-shaped and arranged in the circumferential direction on the inner periphery of the cylindrical portion 12 and whose inner periphery abuts against the outer periphery of the rod-side of the outer shell 2. The plurality of ribs 14 have one or more deformed portions 15, 16, 17 having protrusions 15a, 16a, 17a protruding from the inner periphery toward the outer shell 2 side and concave portions 15b, 15c, 16b, 16c, 17b, 17c adjacent to the protrusions 15a, 16a, 17a on the inner periphery of the plurality of ribs 14.

[0044] In the shock absorber D configured as described above, when the outer shell 2 is inserted into the cylindrical portion 12, the protrusions 15a, 16a, 17a are crushed and adhered to the outer periphery of the outer shell 2, and the deformed protrusions 15a, 16a, 17a escape into the adjacent recesses 15b, 15c, 16b, 16c, 17b, 17c. Therefore, even if there are variations in the height dimension of the ribs 14, variations in the pressing force of each rib 14 can be suppressed, and the holding force for holding the outer shell 2 of the bumper cap 11 can be set as desired. In the shock absorber D of the present embodiment, since the holding force for holding the outer shell 2 of the bumper cap 11 can be set as desired, it is not necessary to set the holding force unnecessarily excessively to avoid the detachment of the bumper cap 11, and cracking of the bumper cap 11 can also be prevented.

[0045] From the above, according to the shock absorber D of the present embodiment, since the holding force for holding the outer shell 2 of the bumper cap 11 can be appropriately set, it is possible to achieve both prevention of cracking of the bumper cap 11 and prevention of detachment of the bumper cap 11 from the outer shell 2.

[0046] In the shock absorber D of the present embodiment, the deformed portion 15 (16, 17) is provided with recesses 15b, 15c (16b, 16c, 17b, 17c) on both sides in the circumferential direction of the protrusion 15a (16a, 17a). In the shock absorber D configured in this way, even if the outer shell 2 is inserted into the cylindrical portion 12 of the bumper cap 11 and the protrusion 15a (16a, 17a) is deformed so as to expand by compression, the deformed protrusion 15a (16a, 17a) can be accommodated in the recesses 15b, 15c (16b, 16c, 17b, 17c) without difficulty. Therefore, the deformed protrusion 15a (16a, 17a) pressed by the outer shell 2 is not caught between the inner peripheral surface 14a of the rib 14 and the outer periphery of the outer shell 2, which would prevent close contact between the inner peripheral surface 14a of the rib 14 and the outer periphery of the outer shell 2.

[0047] As described above, in the shock absorber D of the present embodiment, a plurality of deformation portions 15, 16, and 17 are arranged in the circumferential direction with respect to one rib 14. It is sufficient that the height of one rib 14 is uniform in the circumferential direction. However, since the bumper cap 11 is made of synthetic resin, if sink marks occur after molding, there may be variations in height in the circumferential direction. Even if the height of the rib 14 varies in the circumferential direction in this way, in the shock absorber D of the present embodiment, since a plurality of deformation portions 15, 16, and 17 are arranged in the circumferential direction with respect to one rib 14, when the bumper cap 11 is attached to the outer shell 2, the protrusions 15a, 16a, and 17a at the respective deformation portions 15, 16, and 17 deform according to the height of the rib 14 and adhere to the outer circumference of the outer shell 2. Further, in each of the deformation portions 15, 16, and 17, the protrusions 15a, 16a, and 17a that are crushed and deformed against the outer circumference of the outer shell 2 escape into the adjacent recesses 15b, 15c, 16b, 16c, 17b, and 17c. Therefore, even if the height of the rib 14 is not uniform in the circumferential direction, variations in the tightening force of each rib 14 in the circumferential direction of the cylindrical portion 12 can be suppressed. Therefore, according to the shock absorber D of one embodiment, even if the height of the rib 14 is not uniform in the circumferential direction, the holding force for holding the outer shell 2 of the bumper cap 11 can be appropriately set, and both prevention of cracking of the bumper cap 11 and prevention of dropping of the bumper cap 11 from the outer shell 2 can be achieved. Note that the number of deformation portions provided for one rib 14 can be arbitrarily changed, but it is more effective to prevent cracking and dropping of the bumper cap 11 by installing more within the range where they can be installed on the rib 14.

[0048] As described above, in the shock absorber D of the present embodiment, a plurality of deformation portions 15, 16, and 17 are provided for one rib 14. However, one deformation portion 15, or one deformation portion 16, or one deformation portion 17 may be provided for one rib 14. Even in this case, the shock absorber D can suppress variations in the tightening force of each rib 14 even if there are variations in the height dimension of the rib 14, and the holding force for holding the outer shell 2 of the bumper cap 11 can be set as desired.

[0049] Also, in the shock absorber D of the present embodiment, the concave portions 15b, 15c, 16b, 16c, 17b, 17c are adjacent to the protrusions 15a, 16a, 17a in the circumferential direction of the rib 14, and the deformation portions 15, 16, 17 are formed along the axial direction of the cylindrical portion 12 over the entire length of the inner circumferential surface 14a of the rib 14. According to the shock absorber D configured in this way, when the bump cap 11 is manufactured by injection molding in which synthetic resin as a material is injected into a mold and molded, when the molded bump cap 11 is pulled out axially from the mold, the deformation portions 15, 16, 17 are not caught by the mold, so that the operation of pulling out the molded bump cap 11 from the mold becomes easy.

[0050] Furthermore, in the shock absorber D of the present embodiment, the ribs 14 are provided in an even number of 4 or more at equal intervals in the circumferential direction with respect to the cylindrical portion 12, and the deformation portions 15, 16, 17 are arranged at positions that are point-symmetrical about the center of curvature O of the cylindrical portion 12. In the shock absorber D configured in this way, since the ribs 14 are provided in an even number of 4 or more at equal intervals in the circumferential direction with respect to the cylindrical portion 12, each rib 14 has a positional relationship of facing the rib 14 on the opposite side by 180 degrees in the circumferential direction of the cylindrical portion 12. Also, since the deformation portions 15, 16, 17 are arranged at positions that are point-symmetrical about the center of curvature O of the cylindrical portion 12, the deformation portions 15(16, 17) provided on the ribs 14, 14 facing each other are also arranged on the opposite sides by 180 degrees and face each other. Therefore, according to the shock absorber D configured in this way, when the outer shell 2 is inserted into the cylindrical portion 12, the protrusions 15a(16a, 17a) of the deformation portions 15(16, 17) facing each other on the opposite sides by 180 degrees are in close contact with each other across the outer periphery of the outer shell 2, so that the pressing force with which each rib 14 presses the outer shell 2 becomes more stable. Note that when the deformation portions 15, 16, 17 are not arranged at positions that are point-symmetrical about the center of curvature O of the cylindrical portion 12, as long as three or more ribs 14 are provided with respect to the cylindrical portion 12, any number of ribs can be provided within the range that can be installed on the inner circumference of the cylindrical portion 12.

[0051] In addition, in the shock absorber D of the present embodiment, the total volume of the concave portions 15b and 15c (16b, 16c, 17b, 17c) is equal to or greater than the volume by which the protrusions 15a (16a, 17a) protrude from the inner peripheral surface 14a of the rib 14. In the shock absorber D configured in this way, when the outer shell 2 is inserted into the cylindrical portion 12, even if the protrusions 15a (16a, 17a) are crushed and deformed by the outer shell 2, all of the deformed protrusions 15a (16a, 17a) can be accommodated within the concave portions 15b and 15c (16b, 16c, 17b, 17c). According to the shock absorber D configured in this way, since the deformed protrusions 15a (16a, 17a) are prevented from protruding from the inner peripheral surface 14a toward the outer shell 2 side, even if there is a dimensional error in the height of the rib 14, the entire inner peripheral surface 14a can be brought into close contact with the outer shell 2. Also, even when the height of the rib 14 is higher than the designed dimension, since the protrusions 15a (16a, 17a) can be suppressed from increasing the pressing force of the outer shell 2, it is possible to more effectively achieve both prevention of cracking and prevention of detachment of the bumper cap 11.

[0052] Note that the protrusions 15a (16a, 17a) may be elastically deformed when crushed by the outer shell 2 and restored to their original shape when the bump cap 11 is removed from the outer shell 2. However, they may also be plastically deformed when crushed by the outer shell 2 and not restored but remain accommodated within the recesses 15b, 15c (16b, 16c, 17b, 17c). In this way, when the protrusions 15a (16a, 17a) are plastically deformed and accommodated within the recesses 15b, 15c (16b, 16c, 17b, 17c) when crushed by the outer shell 2, it is possible to suppress the protrusions 15a (16a, 17a) from exerting a resilient force and applying a pressing force that compresses the outer shell 2. In the shock absorber D configured in this manner, when the height of the rib 14 is lower than the designed dimension, the protrusions 15a (16a, 17a) adhere to the outer shell 2 and increase the pressing force of the rib 14. When the height of the rib 14 is higher than the designed dimension, the pressing force of the rib 14 increases due to dimensional error. However, since the protrusions 15a (16a, 17a) are accommodated within the recesses 15b, 15c (16b, 16c, 17b, 17c) and do not exert an excessive resilient force, the pressing force of the rib 14 does not become higher than that caused by design error.

[0053] Therefore, according to the shock absorber D configured such that the protrusions 15a (16a, 17a) are plastically deformed and accommodated within the recesses 15b, 15c (16b, 16c, 17b, 17c) when crushed by the outer shell 2, it is possible to more effectively achieve both prevention of cracking and prevention of detachment of the bump cap 11.

[0054] In addition, in the above-described embodiment, a plurality of deformation portions 15, 16, and 17 are arranged in the circumferential direction with respect to each rib 14. However, as in the bumper cap 11A of the shock absorber of the first modification of the embodiment shown in FIG. 5, a plurality of deformation portions 18 may be arranged in the axial direction with respect to the rib 14. In this example, the deformation portion 18 includes a protrusion 18a having an isosceles triangular cross-section, and recesses 18b and 18c that are provided adjacent to the protrusion 18a on both sides of the protrusion 18a in the vertical direction in FIG. 5, which is the axial direction of the cylindrical portion 12, and both have the same isosceles triangular cross-sectional shape. The protrusion 18a and the recesses 18b and 18c have a shape in which the cross-sectional shape is continuous over the entire circumferential length with respect to the rib 14, and are provided over the entire circumferential length of the inner circumferential surface 14a of the rib 14.

[0055] Here, the shape of the outer periphery of the upper end, which is the rod side end of the outer shell 2, will be described in detail. As described above, due to the caulking process being applied to the open end of the outer shell 2, the outer periphery of the upper end of the outer shell 2 has a slightly larger diameter than the outer peripheries of other parts. Thus, the outer diameter of the outer shell 2 is not uniform in the axial direction. When a bump cap 11A with a plurality of deformation parts 18 arranged in the axial direction with respect to the rib 14 is attached to such an outer shell 2, the protrusions 18a in each deformation part 18 deform according to the outer diameter of the outer shell 2 and adhere closely to the outer shell 2. Also, in each deformation part 18, the protrusions 18a deformed by being crushed against the outer periphery of the outer shell 2 escape into the adjacent recesses 18b, 18c. Therefore, even if the outer diameter of the outer shell 2 is not uniform in the axial direction, variations in the tightening force of each rib 14 in the axial direction of the cylindrical part 12 can be suppressed. Thus, according to the shock absorber of the first modification example of one embodiment, even if the outer diameter of the outer shell 2 is not uniform, the holding force for holding the outer shell 2 of the bump cap 11 can be appropriately set, and both prevention of cracking of the bump cap 11 and prevention of the bump cap 11 from falling off the outer shell 2 can be achieved. In the shock absorber of the first modification example of the present embodiment, since the deformation part 18 is provided with recesses 18b, 18c on both sides of the protrusion 18a in the axial direction of the cylindrical part 12, the deformed protrusion 18a pressed by the outer shell 2 will not be caught between the inner peripheral surface 14a of the rib 14 and the outer periphery of the outer shell 2, preventing close contact between the inner peripheral surface 14a of the rib 14 and the outer periphery of the outer shell 2.

[0056] In addition, as described above, the cross-sectional shapes of the protrusions 15a (16a, 17a) and the recesses 15b, 15c (16b, 16c, 17b, 17c) of the deformation parts 15 (16, 17) are not limited to triangular shapes and may be other shapes.

[0057] Also, when the deformation portions 15, 16, 17 are provided not over the entire length of the inner peripheral surface 14a of the rib 14 but partially along the axial direction of the cylindrical portion 12, the deformation portions 15, 16, 17 may be arranged offset in the axial direction of the cylindrical portion 12. When the deformation portions 15, 16, 17 are provided not over the entire length of the inner peripheral surface 14a of the rib 14 but partially along the axial direction of the cylindrical portion 12, the deformation portions 15, 16, 17 may be arranged on the rib 14 so as to overlap in the circumferential direction of the cylindrical portion 12.

[0058] Furthermore, when the deformation portions 15, 16, 17 are provided not linearly but pointwise with respect to the rib 14, they may be provided so as to be scattered at random positions with respect to the rib 14.

[0059] As described above, the preferred embodiments of the present invention have been described in detail, but modifications, deformations, and changes are possible without departing from the scope of the claims.

Explanation of Reference Numerals

[0060] 1... shock absorber body, 2... outer shell, 3... rod, 10... bump cushion, 11... bump cap, 12... cylindrical portion, 13... stopper portion, 14... rib, 15, 16, 17... deformation portion, 15a, 16a, 17a... protrusion, 15b, 15c, 16b, 16c, 17b, 17c... recess, D... shock absorber, O... center of curvature

Claims

1. A shock absorber body having an outer shell and a rod axially movably inserted into the outer shell, generating a damping force when the rod moves relative to the outer shell; A cylindrical bump cushion mounted on the outer periphery of the rod; A bump cap which is cylindrical and mounted on the outer periphery of the outer shell, and The bump cap includes A cylindrical portion; An annular stopper portion provided at the rod-side end of the cylindrical portion, facing the bump cushion in the axial direction of the rod and having the rod inserted through the inner circumferential side thereof; A plurality of ribs which are arc-shaped and arranged side by side in the circumferential direction on the inner circumference of the cylindrical portion, and whose inner circumferences are in contact with the outer circumference of the rod-side of the outer shell, and The plurality of ribs have one or more deformation portions having protrusions protruding from the inner circumferential surface of the rib toward the outer shell side and recesses adjacent to the protrusions on the inner circumferences of the plurality of ribs. A shock absorber characterized by the above.

2. The deformation portion has the recesses on both sides in the circumferential direction or the axial direction of the protrusion. The shock absorber according to claim 1, characterized by the above.

3. A plurality of the deformation portions are provided at positions shifted in the circumferential direction of the cylindrical portion with respect to one rib. The shock absorber according to claim 1 or 2, characterized by the above.

4. A plurality of the deformation portions are provided at positions shifted in the axial direction of the cylindrical portion with respect to one rib. The shock absorber according to claim 1 or 2, characterized by the above.

5. Four or more even numbers of the ribs are provided at equal intervals in the circumferential direction with respect to the cylindrical portion, and The deformation portions are arranged at positions point-symmetric about the center of curvature of the cylindrical portion. The shock absorber according to any one of claims 1 to 3, characterized by the above.

6. The total volume of the recesses in the deformation portion is not less than the volume of the protrusion protruding from the inner circumferential surface of the rib. The shock absorber according to any one of claims 1 to 5, characterized by the above.

7. The recess is adjacent to the protrusion in the circumferential direction of the rib, and The deformation portion is formed over the entire length of the inner circumferential surface of the rib along the axial direction of the cylindrical portion. The shock absorber according to claim 1, characterized by the above.

8. When the bump cap is mounted on the outer periphery of the outer shell, the protrusion is plastically deformed and accommodated in the recess. The shock absorber according to any one of claims 1 to 7, characterized by the above.

Images