JP5937491B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber, and in particular, can reduce an impact generated between the tip of an inner tube and the bottom of an outer tube.

Generally, in a front fork provided as a shock absorber for a two-wheeled vehicle, the inner tube and the outer tube slide due to the elastic force of a spring provided between the inner tube and the outer tube due to vibration between the axle and the vehicle body. Although it absorbs, when absorbing vibration so that the length of the front fork is the shortest, the tip of the inner tube as a sliding member may collide with the bottom of the outer tube and damage the two . As a countermeasure against this collision, as shown in Patent Document 1, an elastic member is provided on the top cap side, and the impact received on the top cap side by this elastic member is reduced. In Patent Document 2, an elastic member such as a stopper rubber is provided on the cap side as a fork bolt to protect the cap.
However, according to such a configuration, in the effective length of the elastic member in the axial direction, the stroke of the sliding member in the top cap direction is shortened, and there is a drawback that the vibration absorption capability is impaired.

Japanese Patent No. 3847384 Japanese Utility Model Publication No. 3-110231

  The present invention can ensure sufficient vibration absorption capability by setting the stroke of the inner tube as long as possible while reducing the impact generated between the tip of the inner tube and the top cap of the outer tube. It is an object to provide a shock absorber.

As a configuration of the shock absorber for solving the above problems, an inner tube whose lower end is closed, an outer tube whose upper end is closed by a top cap, and whose lower end is inserted coaxially into the upper end of the inner tube , and an outer tube inner in periphery, in a buffering device provided with an elastic member provided on the top cap, provided with install them mounting means while applying a shrinkage preload top cap direction to the elastic member, mounting means, the elasticity of the The pressure receiving body is configured to include a pressure receiving body that abuts on the member, and a regulation unit that is provided on the outer tube and restricts the movement of the pressure receiving body toward the lower end of the inner tube. The pressure receiving body has a predetermined stroke length in the top cap direction. When it moves, it touches the upper end of the inner tube and the inner tube reduces the stroke length. The regulating means is provided so that the position can be changed along the axis of the outer tube, and the contraction preload is reduced by moving the position of the regulating means in the direction of the top cap. Since the stroke length becomes longer as it becomes larger, the stroke in the top cap direction of the outer tube of the inner tube is made longer than before while adjusting the preload amount when the elastic member is contracted preloading toward the bottom of the outer tube. The vibration absorbing performance of the shock absorber itself can be enhanced.
As another configuration of the shock absorber for solving the above problem, the outer tube includes a rod that hangs down from the top cap , passes through the pressure receiving body, and is coaxially inserted into the inner tube, and the regulating means is a rod. than being secured to, in addition to the above effects, it is possible to reduce the impact by elastic member be the tip of the inner tube collides with the pressure receiver, since the pressure receiving member is movable along the rod.
As another configuration of the cushioning device for solving the above problems, than regulating means is fixed to the inner peripheral surface of the outer tube, in addition to the above effects, the tip of the inner tube collides with the pressure receiver Since the pressure receiving body can move along the outer tube, the impact can be reduced by the elastic member.

It is sectional drawing of the front fork by this invention. It is a principal part expanded sectional view of a front fork. It is a figure which shows the load characteristic with respect to the stroke change of the front fork of the past and this invention. It is an operation | movement figure of an elastic member. It is a figure which shows the other fixed form of the retaining ring which supports a pressure receiving body. It is a figure which shows the other fixed form of the retaining ring which supports a pressure receiving body.

  Hereinafter, the present invention will be described in detail through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included in the invention. It is not necessarily essential to the solution, but includes a configuration that is selectively adopted.

  1 and 2 are cross-sectional views of a front fork of a two-wheeled vehicle showing an embodiment of a shock absorber according to the present invention. In each figure, a front fork S has a predetermined length and an inner tube having a long hole 1m. 1, a spring 2 that sits on the bottom 1 a side of the inner tube 1 and rises in the inner tube 1, an outer tube 3 that is coaxially inserted on the upper side of the inner tube 1, and an upper end of the outer tube 3 A top cap 4 provided, a piston rod 5 that is suspended from the top cap 4 and coaxially inserted into the inner tube 1, is attached to the lower end side of the piston rod 5, and is seated on the upper end of the spring 2. Piston member 6 protrudes toward the inner tube 1 from the lower surface side of the top cap 4, and the lower surface is supported by the pressure receiving body 7. More comprised an elastic member 8 to be.

The lower end of the inner tube 1 is closed by a bottom cap 1 f, and the upper surface of the bottom cap 1 f functions as a bottom portion 1 a on the inner peripheral side of the inner tube 1. An axle holder 1c having an axle through hole 1b for supporting the axle is attached to the outer periphery of the lower end of the inner tube 1.
A rod guide 10 that slides on the outer periphery of a piston rod 5 to be described later is fixed to the inner peripheral surface of the inner tube 1, and slides along the axial direction of the piston rod 5 as the inner tube 1 moves. To do.
Oil E is stored in the inner tube 1 so that the position of the liquid level exceeds, for example, the rod guide 10.

  The outer tube 3 is set such that the upper side of the inner tube 1 is coaxially inserted and the inner diameter is slightly larger than the outer diameter of the inner tube 1. Between the outer tube 3 and the inner tube 1, it is configured to be slidable by interposing a bearing made of a slide bearing. More specifically, the upper bearing 3 c is fitted on the upper outer periphery of the inner tube 1 and the lower bearing 3 d is fixed to the lower inner periphery of the outer tube 3. As a result, the inner tube 1 and the outer tube 3 can slide smoothly with each other.

  The lower bearing 3d is fixed to the inner peripheral surface of the expanded portion 3b at the lower end of the outer tube 3 by, for example, press-fitting, and an oil seal 3a that is in sliding contact with the inner tube 1 via a washer 3f is provided below the lower bearing 3d. . The oil seal 3a is secured and secured by a retaining ring 3g that fits into a groove formed on the inner peripheral surface of the enlarged diameter portion 3b. A dust seal 3e covering the space between the inner tube 1 and the outer tube 3 is fixed to the open end of the outer tube 3 below the retaining ring 3g.

A top cap 4 is screwed into the upper end opening of the outer tube 3, and an O-ring 4 a is interposed between the top cap 4 and the upper inner peripheral surface of the outer tube 3, whereby the outer tube 3. The upper end side of is closed. Therefore, the space above the oil E stored in the front fork is closed, thereby forming an air spring chamber in the shock absorber.
4b is a bolt that is screwed into the screw hole at the upper end of the piston rod 5 through the thin-walled portion at the center of the top cap 4, whereby the piston rod 5 is firmly fixed to the top cap 4 and the top It hangs down from the piston rod mounting surface 4p of the cap 4 and is inserted into the inner tube 1 coaxially. A piston member 6 on which the upper end of the spring 2 is seated is provided at the lower end of the piston rod 5.

The piston member 6 includes an oil flow passage (not shown) that circulates oil E in the axial direction of the piston rod 5 and a piston ring on the outer periphery, and the oil flow passage while the outer periphery is in sliding contact with the inner peripheral surface of the inner tube 1. A damping force is generated by circulating oil E in the tank. Further, the spring 2 expands and contracts when the piston member 6 moves with respect to the inner tube 1 together with the outer tube 3.
Reference numeral 6b denotes a rebound spring, which is a buffer member provided so that the piston member 6 does not directly collide with the rod guide when the front fork S is fully extended, and 6a is the rebound spring 6b. The lower end of the seat is a seat.

  The elastic member 8 protrudes from the lower surface side of the top cap 4 toward the inner tube 1 and is supported by an annular pressure receiving body 7 having a lower surface made of a washer. The elastic member 8 is fitted in a ring-shaped step 4 m on the lower inner periphery of the top cap 4 in a sliding contact state with the upper outer peripheral surface of the piston rod 5, and protrudes downward from the lower surface 4 c of the top cap 4. The elastic member 8 is formed of a flexible material such as a rubber material or a soft resin, but may be formed of a coil spring.

In the present embodiment, the pressure receiving body 7 is fastened to the piston rod 5 in a state in which the elastic member 8 is applied with the contraction preload in the direction of the top cap 4 by the pressure receiving body 7. That is, the elastic member 8 extends to the position indicated by the broken line a as shown in FIG. 2 in the state where there is no upward pressure by the pressure receiving body 7, and the lower end level of the elastic member 8 is at the position L1. However, in this embodiment, when pressure (preload) in the upward direction (top cap 4 direction) is applied to the lower end of the elastic member 8 by the pressure receiving body 7, the elastic member 8 contracts to the position indicated by the solid line b. The lower end level is deformed to the position of L2, and the pressure receiving body 7 is fixed by the retaining ring 11 in a state where this deformation is applied. That is, the pressure receiving body 7 and the retaining ring 11 constitute an attachment means for attaching the elastic member 8 with a preload applied.
The retaining ring 11 is an annular fixture such as a C ring or an E ring, and is fixed to an annular groove 20 formed at a position where a preload can be applied to the elastic member 8 on the outer peripheral surface of the piston rod 5. The annular groove 20 is a positioning means for positioning the position of the retaining ring 11, that is, the position of the pressure receiving body 7, formed as a groove recessed in an annular shape along the circumferential direction on the outer peripheral surface of the piston rod 5. Further, the retaining ring 11 and the annular groove 20 function as a restricting means for restricting the movement of the pressure receiving body 7 toward the bottom portion of the inner tube 1.
Therefore, in this embodiment, as shown in FIG. 2, the stroke until the tip 1z of the inner tube 1 collides with the lower surface 7b of the pressure receiving body 7 is increased by the distance K from the level L1 to the level L2.

FIG. 3 shows a comparative example of the present invention and a conventional example (a state in which no pressure is applied to the elastic member 8 by the pressure receiving body 7), the horizontal axis is the stroke length, and the vertical axis is the pressure receiving load of the front fork S. The broken line F indicates the characteristics of the conventional example, and the solid line G indicates the characteristics of the present embodiment.
In FIG. 3, M1 is the stroke of the conventional elastic member 8, and M2 is the stroke of the elastic member 8 of this embodiment. As is clear from the drawing, the stroke is S2 in the conventional example with respect to the effective stroke length S1, whereas in the present invention, the stroke is S3 and the elastic member 8 is shortened as the front fork S. It can be seen that the stroke becomes longer. Strokes S2 and S3 are effective strokes before coming into contact with the elastic member 8, and are regions operating by a spring, an air spring, and a damping action.
As can be seen from the figure, the range in which the stroke is increased by the distance K of the elastic member 8 is a portion that supports a large load in the front fork S. Therefore, an increase in the stroke in this range means that a larger load can be supported.For example, when exceeding a step where a particularly large load acts when the vehicle travels, Even when the tip 1z of the inner tube 1 collides with the pressure receiving body 7, according to the present invention, it can be operated within the range of the effective stroke, and collision can be avoided.
Note that the distance K of the difference between L1 and L2 is preferably about 2 to 3 mm, for example.

In the above configuration, the operation of the front fork S is as follows.
When a force in the direction of contracting the front fork S acts between the lower axle side and the upper vehicle body side, a compressive force is applied to the spring 2 and the air spring of the air spring chamber, and the tip 1z of the inner tube 1 is at the top. Move in the direction of cap 4. The movement of the tip 1z is brought into contact with the lower surface 7b of the pressure receiving body 7 and compresses the elastic member 8 to which the preload is applied, as shown in FIG. Further, as shown in FIG. 4B, the tip 1z of the inner tube 1 moves and stops until the pressure receiving body 7 comes into contact with the lower surface 4c of the top cap 4. At this time, the elastic member 8 is in the maximum compressed state.

When a force in the extending direction is applied to the front fork S, the pressure receiving body 7 is pressed downward by the restoring force of the elastic member 8, and the elastic member 8 extends to a position b shown in FIG. At this time, the pressure receiving body 7 also stops at the position of the retaining ring 11, and the inner tube 1 returns to the original position by the restoring force of the spring 2 and the air spring, with the tip 1z separating from the lower surface 7b of the pressure receiving body 7. Thus, the front fork S extends to the maximum extension position. Since the inner tube 1 is filled with the oil E up to the rod guide 10, the piston member 6 slides in the inner tube 1 as the front fork S extends, thereby increasing the extension speed of the front fork S. A damping force for deceleration is applied.
Further, the rebound spring 6b provided on the upper part of the piston member 6 exhibits an effect as a cushioning material for preventing the rod guide 10 and the piston member 6 from colliding with force when the front fork S is fully extended.

  According to the above configuration, there is no possibility that the top cap 4 and the tip 1z of the inner tube 1 are damaged by the cushioning force of the elastic member 8, and it is possible to extend the life, and the pressure receiving body in a state in which the elastic member 8 is preloaded. 7, the stroke of the inner tube 1 in the direction of the top cap 4 can be lengthened, so that the vibration absorption capability of the front fork S itself can be increased without impairing the cushion performance of the spring 2 and the air spring.

In the embodiment described above, the retaining ring 11 that supports the pressure receiving body 7 that applies the preload to the elastic member 8 is fixed to the piston rod 5. However, the retaining ring 11 may be fixed to the inner peripheral surface of the outer tube 3. .
Specifically, as shown in FIG. 5A, an annular shape that is recessed along the circumferential direction of the inner peripheral surface at a position where a preload can be applied to the elastic member 8 on the inner peripheral surface of the outer tube 3. A groove 21 is formed. Then, when fitted in the annular groove 21, the inner peripheral edge of the retaining ring 11 protrudes from the inner peripheral surface of the outer tube 3 toward the center, and the outer peripheral side of the pressure receiving body 7 is supported on the inner peripheral side of the retaining ring 11. What is necessary is just to comprise. Even if comprised in this way, a preload can be given to the elastic member 8 with the pressure receiving body 7, and the effect similar to the said embodiment can be acquired.
Further, as another configuration for fixing the pressure receiving body 7 to the inner peripheral surface of the outer tube 3, as shown in FIG. 5B, the lower surface 7b of the pressure receiving body 7 can come into contact with the inner peripheral surface of the outer tube 3. A stepped portion 22 may be formed, and the pressure receiving body 7 may be fixed to the inner peripheral surface of the outer tube 3 by the stepped portion 22.

Moreover, although the said embodiment demonstrated as what forms the annular groove 20 which fixes the retaining ring 11 in the piston rod 5, it is not limited to this, It is provided so that two or more may be provided along the axis line of the piston rod 5. Also good.
Specifically, as shown in FIG. 6 (a), a plurality of annular grooves 20A; 20B; 20C are formed on the outer peripheral surface of the piston rod 5 so as to be spaced apart from each other by a predetermined distance along the axial direction. The preload applied to the member 8 can be adjusted, and the stroke amount of the front fork S and the vibration absorption capacity can be adjusted. Further, when the pressure receiving body 7 is fixed on the inner peripheral surface of the outer tube 7, a plurality of annular grooves 21A; 21B; 21C are arranged on the inner peripheral surface of the outer tube 3 as shown in FIG. By forming it at a predetermined distance along the direction, the preload applied to the elastic member 8 can be adjusted, and the stroke amount of the front fork S and the vibration absorption capability can be adjusted.

  Moreover, in the said embodiment, although the pressure receiving body 7 was demonstrated as cyclic | annular (ring shape), for example, when not providing the piston rod 5, a disk shape may be sufficient and the lower surface of the elastic member 8 can be supported. If it is a shape, you may change suitably.

1 Inner tube, 2 Spring, 3 Outer tube,
4 top cap, 5 piston rod, 7 pressure receiving body, 8 elastic member, 11 retaining ring.

Claims (3)

An inner tube whose lower end is closed ;
An outer tube whose upper end is closed by a top cap and whose lower end is coaxially inserted into the upper end of the inner tube;
On the inner peripheral side of the outer tube, an elastic member provided on the top cap ,
Comprising a install them mounting means in a state where the plus shrinkage preload to the elastic member top cap direction,
The attachment means is composed of a pressure receiving body that comes into contact with the elastic member, and a regulation means that is provided on the outer tube and restricts movement of the pressure receiving body in the lower end direction of the inner tube,
The pressure-receiving body contacts the upper end of the inner tube when the inner tube moves in a top cap direction by a predetermined stroke length, and the top cap when the inner tube moves beyond the stroke length. Provided to be movable in the direction,
The restricting means is provided such that its position can be changed along the axis of the outer tube, and the contraction preload is increased and the stroke length is lengthened by moving the position of the restricting means in the direction of the top cap. A shock absorber characterized by. The outer tube includes a rod that hangs down from the top cap , passes through the pressure receiving body, and is coaxially inserted into the inner tube ,
Damping device according to claim 1, wherein said regulating means is secured to said rod. Damping device according to claim 1, wherein said regulating means is fixed to the inner peripheral surface of the outer tube.

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