Shock absorber
Patent Information
- Application Number
- JP2024080284
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-16
- Publication Date
- 2025-11-28
Smart Images
Figure 2025174171000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a shock absorber. [Background technology]
[0002] A shock absorber is used, for example, by being interposed between the vehicle body and rear wheel of a straddle-type vehicle, and suppresses vibrations between the vehicle body and rear wheel by the damping force generated when the shock absorber is extended or contracted.
[0003] Specifically, the shock absorber comprises a shock absorber body having an outer tube and a piston rod inserted into the outer tube so as to be freely movable in the axial direction, and which generates a damping force that impedes expansion and contraction when the shock absorber expands and contracts, as well as a bumper rubber arranged on the outer periphery of the tip side of the piston rod, an annular retaining member that holds the bumper rubber and is attached to the piston rod, a C-shaped piston rod side spring bearing supported by the retaining member at its lower end, a tube side spring bearing attached to the outer periphery of the outer tube, and a suspension spring consisting of a coil spring interposed between the piston rod side spring bearing and the tube side spring bearing (see, for example, Patent Document 1).
[0004] In conventional shock absorbers, the outer tube with the tube-side spring bearing attached is inserted onto the inner periphery of the suspension spring, the piston rod is inserted into the C-shaped piston rod-side spring bearing so that the piston rod-side spring bearing fits onto one end of the suspension spring, the piston rod and piston rod-side spring bearing are inserted into the retaining member that holds the bump rubber, and a bracket is then attached to the tip of the piston rod.This fixes the piston rod-side spring bearing, retaining member, and bump rubber to the piston rod, and the suspension spring is interposed in a compressed state between the piston rod-side spring bearing and the tube-side spring bearing.
[0005] When the shock absorber configured in this manner is installed between the body and rear wheel of the saddle-riding vehicle, it elastically supports the body with the spring force exerted by the suspension spring, and when it expands or contracts, the shock absorber body generates a damping force, thereby suppressing vibration of the body. [Prior art documents] [Patent documents]
[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-52671 Summary of the Invention [Problem to be solved by the invention]
[0007] As described above, conventional shock absorbers are equipped with a piston rod side spring bearing that supports the suspension spring and a retaining member that holds the bump rubber. The piston rod side spring bearing and the retaining member are made of metal and must be formed by cutting after casting or forging, which poses the problem of increased manufacturing costs and weight.
[0008] Furthermore, when disassembling the shock absorber for maintenance, the suspension spring must be compressed to separate the piston rod side spring bearing from the retaining member, and the piston rod side spring bearing must be removed, and the bracket must also be removed from the piston rod to remove the retaining member from the piston rod, making the maintenance work complicated.
[0009] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shock absorber that can reduce manufacturing costs, achieve weight reduction, and facilitate maintenance work. [Means for solving the problem]
[0010] In order to solve the above-mentioned problems, the shock absorber of the present invention comprises a shock absorber body having an outer tube and a piston rod inserted into the outer tube so as to be axially movable, a cylindrical bump rubber arranged on the outer periphery of the tip side of the piston rod, a piston rod side spring bearing that is annular and attached to the tip side of the piston rod and holds the outer periphery of the bump rubber, a tube side spring bearing that is attached to the outer tube, and a suspension spring that is interposed between the piston rod side spring bearing and the tube side spring bearing, the piston rod side spring bearing being made of synthetic resin and having a support portion that supports one end of the suspension spring and a holding portion that is connected to the side of the support portion opposite the outer tube and holds the outer periphery of the bump rubber, and is formed of multiple pieces that can be disassembled in a direction perpendicular to the axial direction of the piston rod.
[0011] In the shock absorber configured in this manner, the piston rod-side spring bearing is made of synthetic resin and is formed of multiple pieces that can be disassembled in a direction perpendicular to the axial direction of the piston rod, and each piece can be manufactured using a mold, which eliminates the need for tedious processing such as cutting after casting or forging, and makes the piston rod-side spring bearing lightweight. Furthermore, because the shock absorber configured in this manner can be disassembled in a direction perpendicular to the axial direction of the piston rod, the piston rod-side spring bearing can be removed from the piston rod without compressing the suspension spring and removing the bracket from the piston rod, which makes it easy to remove the piston rod-side spring bearing during maintenance.
[0012] Furthermore, the piston rod-side spring bearing in the shock absorber may have a hole that communicates between the inside and outside, and each piece may have a notch that forms a hole that communicates with one or both of the mating surfaces of adjacent pieces. With a shock absorber configured in this manner, no holes are provided in the pieces, so it is possible to prevent weld lines from occurring when the pieces are injection molded, and water that has entered the piston rod-side spring bearing can be discharged through the hole while suppressing a decrease in the strength of the piston rod-side spring bearing.
[0013] Furthermore, each piece of the shock absorber may have the same shape, and in this case, the shock absorber does not require the possession of different molds, and the storage and management of the pieces is easy, thereby further reducing manufacturing costs.
[0014] The shock absorber is attached to the tip of the piston rod and comprises a bracket having an annular opposing surface axially opposing the end of the piston rod side spring bearing opposite the outer tube, and a protrusion protruding from the inner periphery of the opposing surface towards the piston rod and fitting into the inner periphery of the piston rod side spring bearing, and an annular plate stacked on the opposing surface, wherein the piston rod side spring bearing has an annular plate opposing surface on the opposite outer tube side that axially opposes the opposing surface of the bracket and abuts against the plate, and the inner diameters of the plate and the plate opposing surface may be equal and the outer diameter of the plate may be equal to or greater than the plate opposing surface.
[0015] With a shock absorber configured in this manner, even if the outer diameter of the opposing surface of the bracket is smaller than the outer diameter of the plate opposing surface of the piston rod side spring bearing, the surface pressure acting on the plate opposing surface can be reduced, and creep of the piston rod side spring bearing can be suppressed. [Effects of the Invention]
[0016] As described above, the shock absorber of the present invention can reduce manufacturing costs, reduce weight, and facilitate maintenance work. [Brief explanation of the drawings]
[0017] [Figure 1] FIG. 1 is a side view of a shock absorber according to one embodiment. [Figure 2] FIG. 2 is a plan view of the piston rod side spring bearing. [Figure 3] FIG. 3 is a bottom view of the piston rod side spring bearing. [Figure 4] FIG. 4 is a side view of the piston rod side spring bearing. [Figure 5] FIG. 5 is a perspective view of the piece as seen from above. [Figure 6] FIG. 6 is a perspective view of the piece as seen from below. DETAILED DESCRIPTION OF THE INVENTION
[0018] The present invention will be described below based on the embodiments shown in the drawings. As shown in Fig. 1, a shock absorber D in one embodiment is configured to include a shock absorber main body 1 having an outer tube 2 and a piston rod 3 inserted into the outer tube 2 so as to be axially movable, a cylindrical bump rubber 4 arranged on the outer periphery of the tip end of the piston rod 3, an annular piston rod-side spring bearing 5 attached to the tip end of the piston rod 3 and holding the outer periphery of the bump rubber 4, a tube-side spring bearing 6 attached to the outer tube 2, and a suspension spring 7 interposed between the piston rod-side spring bearing 5 and the tube-side spring bearing 6. This shock absorber D is used by being interposed between the body and rear wheel of a saddle-ride vehicle (not shown) to suppress vibrations of the body and the rear wheel.
[0019] Each part of the shock absorber D will be described in detail below. As shown in Fig. 1, the shock absorber main body 1 has a cylindrical outer tube 2 and a piston rod 3 inserted into the outer tube 2 so as to be movable in the axial direction, and when the piston rod 3 moves axially relative to the outer tube 2 in an expansion / contraction operation, a damping force is generated that prevents the piston rod 3 from moving relative to the outer tube 2, thereby damping vibrations of the body and rear wheel of the saddle-riding vehicle.
[0020] More specifically, the shock absorber body 1 includes, although not shown, a cylindrical outer tube 2 with a closed top and a piston rod 3 inserted into the outer tube 2 so as to be axially movable; a piston connected to the piston rod 3 and inserted into the outer tube 2 to divide the interior of the outer tube 2 into an expansion-side chamber and a compression-side chamber; a cylindrical tank 10 integrated with a hollow housing 2a provided laterally at the upper end of the outer tube 2 and arranged parallel to the outer tube 2, and equipped with an air chamber and a liquid chamber; and a valve case installed within the housing 2a to separate the expansion-side chamber and the liquid chamber. The expansion-side chamber and the compression-side chamber are filled with a liquid such as hydraulic oil. An elastic partition is inserted within the tank 10, dividing the interior of the tank 10 into the liquid chamber and the air chamber. The liquid in the tank 10 is the same as the liquid filled in the outer tube 2. The tank 10 may be divided into an air chamber and a liquid chamber by a free piston instead of the elastic partition. The liquid used in the shock absorber D may be other than hydraulic oil, such as water or an aqueous solution, and the gas may be other than an inert gas, such as air.
[0021] The piston is provided with a passage connecting the expansion-side chamber and the compression-side chamber and a piston valve that resists the flow of liquid passing through the passage. The valve case is also provided with a base valve that only allows liquid to flow from the expansion-side chamber to the liquid chamber and resists the flow of liquid, a variable valve that is parallel to the base valve and only allows liquid to flow from the expansion-side chamber to the liquid chamber and can adjust the resistance to the liquid flow, and a check valve that only allows liquid to flow from the liquid chamber to the reservoir. The shock absorber body 1 configured in this way expands and contracts the expansion-side chamber and the compression-side chamber by the piston during expansion / contraction operation, generating a damping force due to the pressure loss that occurs when the liquid passes through the piston valve or the base valve. The damping force generated by the shock absorber body 1 during contraction operation can be adjusted by adjusting the variable valve.
[0022] The internal structure of the shock absorber body 1 is merely an example, and the design can be modified as long as the shock absorber body 1 can generate a damping force that prevents expansion and contraction when the shock absorber body 1 expands and contracts, causing the piston rod 3 to move axially relative to the outer tube 2.
[0023] Next, the outer tube 2 has a connecting portion 2b at the top of its upper end that can be connected to the body of a saddle-riding vehicle. A bracket 13 is attached to the lower end of the piston rod 3 so that the piston rod 3 can be attached to a link that is connected to a swing arm that is swingably attached to the body of the saddle-riding vehicle (not shown) and that rotatably supports the rear wheel. Thus, the shock absorber D of the first embodiment is installed between the vehicle body and the rear wheel in a manner that the outer tube 2 is connected to the vehicle body and the piston rod 3 is connected to the rear wheel.
[0024] In addition, the outer tube 2 has an expanded diameter portion 2c in the middle portion that has a larger outer diameter than other portions, and also has a threaded portion 2d formed over the entire axial length of the outer periphery of the expanded diameter portion 2c.
[0025] An annular tube-side spring bearing 6 and an annular fixing nut 12 are threadedly coupled to the threaded portion 2d of the outer tube 2. The fixing nut 12 and the tube-side spring bearing 6 form a double nut, and when the fixing nut 12 comes into contact with the tube-side spring bearing 6, it prevents the tube-side spring bearing 6 from loosening from the threaded portion 2d. When the fixing nut 12 is rotated and separated from the tube-side spring bearing 6, the tube-side spring bearing 6 is allowed to rotate, and the tube-side spring bearing 6 can be rotated relative to the threaded portion 2d and moved in the vertical direction in FIG. 1. After the tube-side spring bearing 6 is positioned at a desired position, the fixing nut 12 is rotated so that it comes into contact with the tube-side spring bearing 6, and the tube-side spring bearing 6 can be fixed in the desired position.
[0026] In addition, an annular piston rod-side spring bearing 5 is attached to the lower end side of the piston rod 3. A suspension spring 7 made of a coil spring is interposed on the outer periphery of the shock absorber main body 1, between the piston rod-side spring bearing 5 and the tube-side spring bearing 6. In other words, the outer tube 2 of the shock absorber main body 1 and the piston rod 3 are inserted into the suspension spring 7. The piston rod-side spring bearing 5 supports the lower end, which is one end 7a of the suspension spring 7, and the tube-side spring bearing 6 supports the upper end, which is the other end 7b of the suspension spring 7, and the shock absorber main body 1 is constantly biased to extend by the elastic force of the suspension spring 7. Therefore, when the shock absorber D is interposed between the body and rear wheel of a saddle-ride vehicle, the vehicle body is elastically supported by the elastic force generated by the suspension spring 7. Furthermore, when the tube-side spring bearing 6 is rotated in the circumferential direction relative to the outer tube 2, the tube-side spring bearing 6 moves in the axial direction relative to the outer tube 2 in the manner of a feed screw, thereby changing the support position of the other end 7b of the suspension spring 7. If the weight of the vehicle body supported by the suspension spring 7 does not change, the length of the suspension spring 7 in a compressed state does not change, so when the support position of the tube-side spring bearing 6 for the other end 7b of the suspension spring 7 is changed, the distance between the tube-side spring bearing 6 and the connecting portion 2b changes, making it possible to adjust the vehicle height.
[0027] 1, which is the tip of the piston rod 3, the bracket 13 is equipped with: an opposing surface 13b having an annular flat surface perpendicular to the axis of the piston rod 3 at its upper end in FIG. 1; a cylindrical protrusion 13c protruding from the inner periphery of the opposing surface 13b toward the outer tube side in FIG. 1; a main body 13a having a screw hole 13d that opens from the upper end of the protrusion 13c in FIG. 1 and is screw-coupled to a screw portion 3a formed on the outer periphery of the lower end of the piston rod 3; and a bifurcated connecting portion 13e that extends downward from the lower end of the main body 13a and can be hinged to a link that is coupled to a swing arm (not shown).
[0028] The bracket 13 configured in this manner forms a double nut together with a fixing nut 14 that is screwed onto the threaded portion 3a of the piston rod 3 and abuts against the upper end of the protrusion 13c in Figure 1, and is fixed to the piston rod 3 in a manner that prevents loosening.
[0029] The bump rubber 4 is cylindrical and has a plurality of annular grooves provided around its outer periphery in the circumferential direction, and is fitted onto the outer periphery of the lower end side of the piston rod 3 in Fig. 1. The bump rubber 4 is made of urethane resin, rubber, or the like and has elasticity, and when the shock absorber main body 1 contracts and comes into contact with a bump stopper (not shown) attached to the inner periphery of the lower end of the outer tube 2 and is compressed, it exerts a resilient force to absorb the impact when the shock absorber main body 1 is fully contracted.
[0030] The piston rod side spring bearing 5 is made of synthetic resin and includes an annular support portion 5a that faces the suspension spring 7 in the axial direction, and a cylindrical retaining portion 5b that is continuous with the inner periphery of the lower end of the support portion 5a in Fig. 1 on the side opposite the outer tube, and that retains the outer periphery of the lower end of the bump rubber 4 in Fig. 1, and in this embodiment is formed by combining two pieces P. Note that the retention of the outer periphery of the bump rubber 4 by the piston rod side spring bearing 5 includes not only a mode in which the retaining portion 5b always abuts against and holds the outer periphery of the bump rubber 4, but also a mode in which a gap is generated between the inner periphery of the retaining portion 5b and the outer periphery of the bump rubber 4 when the bumper D is fully contracted and the bump rubber 4 abuts against the bump stopper, thereby expanding the compressed outer diameter, but where the retaining portion 5b restrains and holds the outer periphery of the bump rubber 4.
[0031] 4, the support portion 5a is annular and has a plurality of rectangular blind holes 5a1 arranged in the circumferential direction, opening from the outer tube side end facing the suspension spring 7. Although the blind holes 5a1 do not have to be provided in the support portion 5a, providing the blind holes 5a1 in the support portion 5a reduces the weight of the support portion 5a and improves its strength.
[0032] 1 to 4, the retaining portion 5b includes a cylindrical portion 5b1 connected to the lower end of the support portion 5a in FIG. 1; a tapered inclined portion 5b2 connected to the lower end of the cylindrical portion 5b1 on the side opposite the outer tube in FIG. 1; an annular flange 5b3 protruding inward from the inner periphery of the lower end of the inclined portion 5b2; and two holes 5b4, 5b4 that penetrate the inclined portion 5b2 and communicate between the inside and outside of the piston rod-side spring bearing 5. The annular end face opposite the outer tube, which is the lower end face of the retaining portion 5b in FIG. 1, is a flat surface perpendicular to the axis of the piston rod 3, and forms a plate-facing surface 5b5 that axially faces the facing surface 13b of the bracket 13. The plate-facing surface 5b5 is formed by the portion of the retaining portion 5b from the inner peripheral edge of the flange 5b3 to the outer peripheral edge of the lower end of the inclined portion 5b2 in FIG. 1.
[0033] The holes 5b4, 5b4 penetrate the thickness of the inclined portion 5b2 and are provided at positions opposite to each other in the circumferential direction for the purpose of discharging water that has entered the piston rod side spring bearing 5. The number of holes 5b4 provided can be changed.
[0034] The piston rod side spring bearing 5 also has a plurality of grooves 5c formed along the axial direction from the lower end of the inclined portion 5b2 in Figure 2 to the outer periphery of the support portion 5a. Although the piston rod side spring bearing 5 does not necessarily have to have the grooves 5c, providing the grooves 5c in the piston rod side spring bearing 5 makes the piston rod side spring bearing 5 lighter and improves its strength.
[0035] The piston rod-side spring bearing 5 configured in this manner is attached to the outer periphery of the lower end of the piston rod 3 in Fig. 1 via the bracket 13. In detail, the piston rod-side spring bearing 5 is positioned in the radial direction by the convex portion 13c of the bracket 13 inserted into the flange 5b3 of the holding portion 5b, and the piston rod-side spring bearing 5 supports the lower end of the suspension spring 7 in Fig. 1 by the support portion 5a, and is urged toward the opposing surface 13b of the bracket 13 by the elastic force of the suspension spring 7, so that the piston rod-side spring bearing 5 is attached to the piston rod 3 in a state where its axial movement with respect to the piston rod 3 is restricted.
[0036] The plate opposing surface 5b5 of the piston rod-side spring bearing 5 and the opposing surface 13b of the bracket 13 are opposed to each other in the axial direction, and an annular metal plate 16 is interposed between the plate opposing surface 5b5 and the opposing surface 13b. The inner diameter of the plate 16 is equal to the inner diameter of the plate opposing surface 5b5 of the piston rod-side spring bearing 5, and the outer diameter of the plate 16 is equal to or larger than the outer diameter of the plate opposing surface 5b5 of the piston rod-side spring bearing 5.
[0037] The piston rod-side spring bearing 5 is constantly pressed against the bracket 13 by the elastic force of the suspension spring 7, and receives a load from the bracket 13 as a reaction to the elastic force of the suspension spring 7. Because the outer diameter of the opposing surface 13b of the bracket 13 is smaller than the outer diameter of the plate opposing surface 5b5 of the piston rod-side spring bearing 5, if the plate 16 is omitted, the load from the bracket 13 acts only on the inner periphery of the plate opposing surface 5b5, and a large surface pressure acts on the inner periphery of the plate opposing surface 5b5. Because the piston rod-side spring bearing 5 is made of synthetic resin, the application of a large surface pressure to the inner periphery of the plate opposing surface 5b5 may cause creep. In contrast to this, if the plate 16 is sandwiched between the opposing surface 13b and the plate opposing surface 5b5, even if the outer diameter of the opposing surface 13b of the bracket 13 is smaller than the outer diameter of the plate opposing surface 5b5 of the piston rod-side spring bearing 5, the plate 16 can reduce the surface pressure acting from the bracket 13 to the plate opposing surface 5b5, thereby suppressing creep of the piston rod-side spring bearing 5. Note that if the strength of the piston rod-side spring bearing 5 is sufficiently high, or if the outer diameter of the opposing surface 13b of the bracket 13 is the same as the outer diameter of the plate opposing surface 5b5, the plate 16 may be eliminated.
[0038] 1 of the support portion 5a of the piston rod-side spring bearing 5 and one end 7a of the suspension spring 7. The washer 15 is provided with an annular support seat 15a on which the one end 7a of the suspension spring 7 is seated, a cylindrical guide portion 15b that rises upward from the inner periphery of the support seat 15a in FIG. 1 and fits onto the inner periphery of the one end 7a of the suspension spring 7, and a cylindrical fitting portion 15c that hangs down from the outer periphery of the support seat 15a in FIG. 1 and fits onto the outer periphery of the support portion 5a of the piston rod-side spring bearing 5. The fitting portion 15c of the washer 15 fits onto the outer periphery of the support portion 5a of the piston rod side spring bearing 5, and the guide portion 15b fits onto the inner periphery of one end 7a of the suspension spring 7, so that the suspension spring 7 is positioned radially relative to the piston rod side spring bearing 5 and is supported by the piston rod side spring bearing 5 without shifting.
[0039] By sandwiching the washer 15 between the piston rod side spring bearing 5 and the suspension spring 7 in this way, the one end 7a that rotates circumferentially when the suspension spring 7 expands or contracts does not come into direct contact with the support portion 5a, thereby preventing wear on the support portion 5a.
[0040] As described above, the piston rod side spring bearing 5 configured in this manner is made up of two radially separable synthetic resin pieces P. Each piece P will be specifically described below.
[0041] 5 and 6, each piece P has the same shape, and to avoid duplication, only one piece P will be described in detail below. Piece P includes an arc-shaped upper portion 20 that axially faces one end 7a of suspension spring 7 and constitutes part of the support portion 5a of piston rod-side spring bearing 5 and part of the cylindrical portion 5b1 of the holding portion 5b, an arc-shaped lower portion 21 that is partially connected to the side opposite the outer tube of the upper portion 20 and constitutes part of the cylindrical portion 5b1, part of the inclined portion 5b2, and part of the flange 5b3 of the holding portion 5b of piston rod-side spring bearing 5, an arc-shaped outer ridge 22 that rises in the axial direction from the outer periphery of a portion of the upper portion 20 that is the end opposite the outer tube and is not connected to the lower portion 21, and an arc-shaped inner ridge 23 that rises in the axial direction from the inner periphery of a portion of the outer tube side end of the lower portion 21 that is not connected to the upper portion 20.
[0042] Each piece P is made of synthetic resin such as nylon 66, polyethylene terephthalate, polypropylene, or polybutylene terephthalate reinforced with glass fiber or carbon fiber.
[0043] Hereinafter, when viewing the piston rod-side spring bearing 5 from the axial direction, the upper part 20 of the piece P comprises a semicircular large-diameter portion 20a which becomes the support part 5a of the piston rod-side spring bearing 5 on the outer tube side, and a semicircular small-diameter portion 20b which is continuous with the end of the large-diameter portion 20a on the side opposite to the outer tube, has a smaller diameter than the large-diameter portion 20a, and becomes the cylindrical part 5b1 of the piston rod-side spring bearing 5. The large-diameter portion 20a also comprises a plurality of blind holes 20a1 which open from the outer-tube side end and become the blind holes 5a1 in the support part 5a.
[0044] When viewed from the axial direction of the piston rod side spring bearing 5, the lower part 21 comprises: a semicircular cylindrical part 21a that shares the same inner and outer diameters as the small diameter part 20b in the upper part 20 and that forms the cylindrical part 5b1 of the piston rod side spring bearing 5; a semiconical tapered part 21b that is connected to the side opposite the outer tube of the semicylindrical part 21a and whose diameter decreases towards the side opposite the outer tube; a semicircular protruding part 21c that protrudes radially inner from the lower end of the tapered part 21b; and notches 21d that are provided on both circumferential ends of the tapered part 21b. The lower part 21 is disposed rotated 90 degrees circumferentially relative to the upper part 20 and is integrated with the upper part 20.
[0045] When viewed from the axial direction of the piston rod side spring bearing 5, the outer protrusion 22 rises in the axial direction from the outer periphery of the quadrant-shaped portion that is at the end of the small diameter portion 20b of the upper portion 20 on the side opposite to the outer tube and is not connected to the lower portion 21, toward the side opposite to the outer tube, and has a quadrant shape.
[0046] The inner ridge 23 is quadrant-shaped and rises axially toward the outer tube from the inner periphery of a quadrant-shaped portion that is the outer tube side end of the semi-cylindrical portion 21a of the lower portion 21 and is not connected to the upper portion 20. The inner ridge 23 has a tapered surface 23a on the outer periphery that slopes so that the thickness increases from the tip to the base end, with the thickness being greatest on the lower portion 21 side, which is the base end.
[0047] The pieces P, P configured in this manner have the same shape and are manufactured by injecting the aforementioned reinforced synthetic resin into a mold (not shown). Therefore, when the circumferential end faces of the upper parts 20, 20 are brought closer together while being supported in a state where they are parallel and facing each other, when the circumferential end faces of the upper parts 20, 20 are brought into contact, the circumferential end faces of the lower parts 21, 21 also come into contact with each other, and the pieces P, P can be combined to form the piston rod-side spring bearing 5. In this way, the piston rod-side spring bearing 5 is formed by two pieces P, P that can be disassembled in a direction perpendicular to the axial direction of the piston rod 3.
[0048] Furthermore, when the pieces P, P are combined as described above, the inner ridge 23 of one piece P is disposed on the inner peripheral side of the outer ridge 22 of the other piece P, forming an annular gap between them. The inner ridge 23, together with the lower part 21, forms the inner peripheral surface of the retaining portion 5b of the piston rod-side spring bearing 5 and abuts against the outer periphery of the bump rubber 4, but the outer ridge 22 is disposed on the outer peripheral side of the inner ridge 23 and does not directly abut against the bump rubber 4. Furthermore, the outer periphery of the upper part 20 and the outer periphery of the lower part 21 are provided with vertical grooves 20c, 21e that form the groove 5c on the outer periphery of the piston rod-side spring bearing 5 when the pieces P, P are combined to assemble the piston rod-side spring bearing 5.
[0049] The circumferential ends 21b1, 21b2 of the tapered portion 21b of the lower portion 21 of each piece P, P form the mating surfaces of the pieces P, P. When the circumferential ends 21b1, 21b2 of the tapered portion 21b of the lower portion 21 of each piece P, P are brought into contact with each other, the notches 21d formed in the circumferential ends 21b1, 21b2 of the tapered portion 21b of the lower portion 21 of each piece P, P face each other, and the facing notches 21d, 21d form holes 5b4, 5b4 in the piston rod-side spring bearing 5. In this way, by providing the notches 21d, 21d in the mating surfaces of each piece P, P, the holes 5b4, 5b4 are formed in the piston rod-side spring bearing 5, so there is no need to provide holes in the piece P itself. Because no holes are provided in the piece P, there is no area where molten resin meets during injection molding of the piece P, preventing weld lines from occurring in the piece P. Therefore, the holes 5b4 can be formed in the piston rod-side spring bearing 5 formed by combining the pieces P, P without causing a fragile weld line in the piece P. Note that, as described above, the notches 21d formed in the mating surfaces at the circumferential ends 21b1, 21b2 of the tapered portion 21b of the lower portion 21 of each piece P, P face each other to form the holes 5b4, 5b4. However, it is also possible to provide a notch 21d in only one of the circumferential ends 21b1, 21b2 of the tapered portion 21b so that one hole 5b4 is formed by one notch 21d when the pieces P, P are combined. Because no holes are formed in the piece P configured in this manner and no weld line is created, the holes 5b4 can be formed in the piston rod-side spring bearing 5 formed by combining the pieces P, P without causing a fragile weld line in the piece P. In order to prevent weld lines from forming, the holes 5d4, 5d4 only need to be formed so as to connect to the mating surfaces of the pieces P, P, and so may be formed so as to connect to the mating surfaces of the protrusions 21c, 21c that form the flange 5b3, or to the mating surfaces of the tapered portion 21b of the lower portion 21 and the small diameter portion 20b of the upper portion 22.
[0050] In the piston rod-side spring bearing 5 formed by combining the two pieces P, P in this way, the fitting portion 15c of the washer 15 fits onto the outer periphery of the large diameter portion 20a of the upper portion 20 of each piece P, P, thereby restricting the combined pieces P, P from separating from each other in the radial direction, which is perpendicular to the axial direction of the piston rod 3. Therefore, the pieces P, P do not come apart, and the piston rod-side spring bearing 5 is maintained in a formed state, and the piston rod-side spring bearing 5 can be attached to the outer periphery of the piston rod 3.
[0051] As described above, the shock absorber D of this embodiment comprises a shock absorber main body 1 having an outer tube 2 and a piston rod 3 inserted into the outer tube 2 so as to be axially movable, a cylindrical bumper rubber 4 arranged on the outer periphery of the tip side of the piston rod 3, a piston rod side spring bearing 5 which is annular and attached to the tip side of the piston rod 3 and holds the outer periphery of the bumper rubber 4, a tube side spring bearing 6 attached to the outer tube 2, and a suspension spring 7 interposed between the piston rod side spring bearing 5 and the tube side spring bearing 6, the piston rod side spring bearing 5 being made of synthetic resin and having a support portion 5a which supports one end 7a of the suspension spring 7 and a holding portion 5b which is connected to the opposite outer tube side of the support portion 5a and holds the outer periphery of the bumper rubber 4, and is formed of multiple pieces P, P which can be disassembled in a direction perpendicular to the axial direction of the piston rod 3.
[0052] According to the shock absorber D configured in this manner, the piston rod-side spring bearing 5 is made of synthetic resin and is formed of a plurality of pieces P, P that can be disassembled in a direction perpendicular to the axial direction of the piston rod 3, and each piece P, P can be manufactured using a mold, which eliminates the need for troublesome processing such as cutting after casting or forging, and makes the piston rod-side spring bearing 5 lightweight. Furthermore, according to the shock absorber D configured in this manner, because it can be disassembled in a direction perpendicular to the axial direction of the piston rod 3, there is no need to compress the suspension spring 7 and remove the bracket 13 from the piston rod 3, and therefore the piston rod-side spring bearing 5 can be removed from the piston rod 3, which makes it easy to remove the piston rod-side spring bearing 5 during maintenance.
[0053] As described above, according to the shock absorber D of this embodiment, it is possible to reduce the manufacturing cost, reduce the weight, and also facilitate the maintenance work.
[0054] Although the piston rod side spring bearing 5 is formed by two pieces P, P as described above, the piston rod side spring bearing 5 may be formed by three or more pieces as long as it can be disassembled in a direction perpendicular to the axial direction of the piston rod 3.
[0055] Moreover, in the shock absorber D of this embodiment, the piston rod-side spring bearing 5 has a hole 5b4 that communicates between the inside and the outside, and each of the pieces P, P has a notch 21d that forms the hole 5b4 that communicates with one or both of the mating surfaces of adjacent pieces P, P. According to the shock absorber D configured in this manner, no hole is provided in the piece P, so it is possible to prevent weld lines from occurring when the piece P is injection molded, and water that has entered the piston rod-side spring bearing 5 can be discharged via the hole 5b4 while suppressing a decrease in the strength of the piston rod-side spring bearing 5.
[0056] Furthermore, in the shock absorber D of this embodiment, each of the pieces P, P has an upper part 20 that is arc-shaped and faces one end 7a of the suspension spring 7 in the axial direction, forming part of the support part 5a and part of the retaining part 5b of the piston rod side spring bearing 5; an arc-shaped lower part 21 that is partly connected to the side opposite the outer tube of the upper part 20 and forms part of the retaining part 5b; an arc-shaped outer ridge 22 that rises in the axial direction from the outer periphery of the part of the upper part 20 that is the end opposite the outer tube and not connected to the lower part 21; and an arc-shaped inner ridge 23 that rises in the axial direction from the inner periphery of the part of the outer tube side end of the lower part 21 that is not connected to the upper part 20, and the inner ridge 23 has a tapered surface 23a on the outer periphery that slopes so that the thickness becomes thicker from the tip to the base end.
[0057] With the shock absorber D configured in this manner, when the shock absorber D is fully contracted and the bump rubber 4 is compressed in the axial direction and expands in diameter in the radial direction, even if the inner ridge 23 facing the outer periphery of the bump rubber 4 is pressed by the expanded bump rubber 4, the tapered surface 23a is provided on the outer periphery of the inner ridge 23 so that the thickness increases from the tip to the base end, making it difficult for the inner ridge 23 to collapse toward the outer periphery and restraining the outer periphery of the bump rubber 4 from expanding in diameter. Furthermore, when the inner ridge 23 collapses outward, the outer ridge 22 arranged on the outer periphery of the inner ridge 23 supports the back surface of the inner ridge 23, preventing the inner ridge 23 from collapsing further and suppressing the expansion of the diameter of the bump rubber 4. Therefore, according to the shock absorber D of this embodiment, even if the piston rod side spring bearing 5 is formed from multiple pieces P, P made of synthetic resin, the outer periphery of the bumper rubber 4 can be restrained to prevent the bumper rubber 4 from expanding in diameter, and the bumper rubber 4 can exert the designed elastic force to cushion the impact when the shock absorber D is fully compressed.
[0058] Furthermore, in the shock absorber D of this embodiment, each piece P, P has the same shape, so there is no need to possess different molds, and storage and management of the pieces P is easy, thereby further reducing manufacturing costs.
[0059] Furthermore, the shock absorber D of this embodiment is attached to the tip of the piston rod 3 and comprises a bracket 13 having an annular opposing surface 13b axially opposing the end of the piston rod side spring bearing 5 on the side opposite to the outer tube, and a protrusion 13c protruding from the inner periphery of the opposing surface 13b towards the piston rod and fitting into the inner periphery of the piston rod side spring bearing 5, and an annular plate 16 stacked on the opposing surface 13b, the piston rod side spring bearing 5 having an annular plate opposing surface 5b5 on the opposite outer tube side facing the opposing surface 13b of the bracket 13 in the axial direction and abutting against the plate 16, the inner diameters of the plate 16 and the plate opposing surface 5b5 being equal and the outer diameter of the plate 16 being equal to or larger than the outer diameter of the plate opposing surface 5b5.
[0060] According to the shock absorber D configured in this manner, even if the outer diameter of the opposing surface 13b of the bracket 13 is smaller than the outer diameter of the plate opposing surface 5b5 of the piston rod side spring bearing 5, the surface pressure acting on the plate opposing surface 5b5 can be reduced, and creep of the piston rod side spring bearing 5 can be suppressed.
[0061] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]
[0062] DESCRIPTION OF SYMBOLS 1 shock absorber body, 2 outer tube, 3 piston rod, 4 bumper rubber, 5 piston rod side spring holder, 5a support portion, 5b holding portion, 5b4 hole, 5b5 plate opposing surface, 6 tube side spring holder, 7 suspension spring, 7a one end of suspension spring, 13 bracket, 13b opposing surface, 13c convex portion, 16 plate, 20 upper portion, 21 lower portion, 21d notch, 22 outer ridge, 23 inner ridge, 23a tapered surface, D shock absorber, P piece
Claims
1. a shock absorber body having an outer tube and a piston rod inserted into the outer tube so as to be movable in an axial direction; a cylindrical bump rubber disposed on the outer periphery of the tip end side of the piston rod; a piston rod side spring bearing that is annular and attached to a tip end side of the piston rod and that holds an outer periphery of the bump rubber; a tube-side spring bearing attached to the outer tube; a suspension spring interposed between the piston rod side spring bearing and the tube side spring bearing, The piston rod side spring bearing is Made of synthetic resin, a support portion that supports one end of the suspension spring; a holding portion connected to the support portion on the side opposite to the outer tube and holding an outer periphery of the bump rubber, The piston rod is formed of a plurality of pieces that can be disassembled in a direction perpendicular to the axial direction of the piston rod. A shock absorber characterized by:
2. the piston rod side spring bearing has a hole communicating the inside with the outside, Each of the pieces is The adjacent pieces have a notch that forms the hole and is connected to one or both of the mating surfaces of the pieces.
2. The shock absorber according to claim 1.
3. The pieces each have the same shape.
2. The shock absorber according to claim 1.
4. a bracket attached to the tip of the piston rod, the bracket having an annular opposing surface axially opposing the end of the piston rod side spring bearing opposite to the outer tube, and a protrusion protruding from an inner periphery of the opposing surface toward the piston rod and fitting into the inner periphery of the piston rod side spring bearing; an annular plate laminated on the opposing surface, the piston rod side spring bearing has an annular plate facing surface on the side opposite the outer tube, the plate facing surface facing the bracket in the axial direction and abutting against the plate, The inner diameter of the plate and the plate opposing surface are equal, and the outer diameter of the plate is equal to or larger than the plate opposing surface.
2. The shock absorber according to claim 1.