JP2003014025A - Front fork - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front fork improving ride quality of a vehicle by absorbing a high frequency vibration input generating when a wheel runs over a protrusion or a stepped part on a road particularly during traveling. SOLUTION: In the front fork, a body side tube 1 and a wheel side tube 2 are slidably fit together, a damper is erected in a center of the wheel side tube, and a suspension spring 6 is interposed between the body side tube 1 and the damper 3. It is characterized by that an adjuster 7 for adjusting an initialization load of the suspension spring is rotatably inserted in a cap 4, the adjuster 7 is coupled with a piston rod 16 of the damper 3 while facing it to the suspension spring 6, and elastic bodies 8 and 9 absorbing high frequency vibration input acting on the piston rod 16 are provided between the cap 4 and the adjuster 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork that serves as both a shock absorber and a fork that is interposed between a vehicle body and an axle of a motorcycle to damp vibrations from the road surface, and particularly absorbs high frequency vibration input. For front forks suitable for.

[0002]

2. Description of the Related Art Generally, a motorcycle has a front fork interposed between a vehicle body and an axle, and vibrations from the road surface are damped by the front fork to improve the riding comfort of the vehicle.

In this type of front fork, for example, as shown in Japanese Utility Model Laid-Open No. 59-56191, an inner tube on the vehicle body side is slidably inserted into an outer tube on the wheel side, and a damper is provided at the center of the outer tube on the wheel side. Standing up, a suspension spring is interposed between the upper end cap of the vehicle body side inner tube and the upper end of the damper.

Further, the damper includes a damper cylinder, a piston rod movably inserted into the damper cylinder via a piston, an expansion side chamber and a compression side chamber defined in the damper cylinder via the piston, and an expansion side provided to the piston. A side valve and a check valve, and a pressure side valve and a check valve provided between the pressure side chamber and the outer reservoir of the damper cylinder are provided.

Therefore, when the front fork is operated on the pressure side, part of the oil in the pressure side chamber flows out to the extension side chamber via the check valve of the piston, and the oil corresponding to the piston rod entry volume flows out to the reservoir via the pressure side valve. At this time, a damping force on the pressure side is generated by the flow resistance of the pressure side valve. Conversely, during extension operation, the piston rod withdrawal volume is sucked from the reservoir into the pressure side chamber via the check valve, and the oil in the extension side chamber flows out to the pressure side chamber via the piston extension side valve. Generates damping force on the extension side due to the flow resistance of.

[0006]

In the above-mentioned conventional front fork, vibrations from the road surface are damped. However, for example, when a vehicle runs over a road protrusion or a step while driving, a high frequency vibration is generated. When the input due to this vibration acts on the front fork, the compression operation may not be performed smoothly.

That is, when a push-up input from the road surface due to high frequency vibration acts on the front fork, the damper attempts to perform a rapid compression operation, but at this time, even if the oil in the pressure side chamber tries to pass through the pressure side valve, the flow rate is too large, Since it cannot pass all at once, the internal pressure of the pressure side chamber rises momentarily. For this reason, the compression operation is not smoothly performed, and the front fork becomes a rod body, and the high-frequency vibration described above becomes an impact and propagates to the vehicle body side and the steering wheel side, resulting in a problem that the riding comfort is deteriorated.

[0008] Therefore, an object of the present invention is to provide a front fork capable of absorbing a high frequency vibration input generated when a wheel gets over a projection or a step on the road during traveling and improving the riding comfort of the vehicle. Is.

[0009]

In order to achieve the above object, the means of the present invention is such that a vehicle body side tube and a wheel side tube are slidably fitted together and a damper is erected at the center of the wheel side tube. In a front fork in which a suspension spring is interposed between a vehicle body side tube and a damper, an adjuster for adjusting the initial setting load of the suspension spring is rotatably inserted into the cap, and the adjuster is suspended. It is characterized in that it is connected to the piston rod of the damper while facing it, and an elastic body for absorbing the high frequency vibration input acting on the piston rod is provided between the cap and the adjuster.

In this case, a dial is provided on the outer periphery of the upper end of the adjuster, a flange extending on the inner peripheral side of the cap is provided on the body of the adjuster, and a flange extending on the outer peripheral side of the adjuster is provided on the inner periphery of the cap, and the dial and the flange It is preferable that the expansion side elastic body is provided between the flange and the pressure side elastic body, and the compression side elastic body is provided between the flange and the flange.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a front fork according to an embodiment of the present invention.

As shown in FIG. 1, in this front fork, a wheel side tube 2 is slidably inserted into a vehicle body side tube 1, a damper 3 is erected at the center of the wheel side tube 2, and A suspension spring 6 is interposed between the upper end cap 4 and the upper end of the damper cylinder 5 of the damper 3.

As is well known, the damper 3 includes a damper cylinder 5, a piston rod 16 movably inserted into the damper cylinder 5 via a piston, an expansion side chamber and a compression side chamber defined in the damper cylinder via the piston. ,
An expansion side valve and a check valve provided on the piston, and a compression side valve and a check valve provided between the pressure side chamber and the outer reservoir of the damper cylinder are provided.

Therefore, as in the conventional case, when the front fork is operated on the pressure side, a part of the oil in the pressure side chamber flows out to the extension side chamber via the check valve of the piston, and at the same time, the oil corresponding to the piston rod entering volume is passed through the pressure side valve. It flows out to the reservoir, and at this time, the flow-side resistance of the pressure-side valve generates a damping force on the pressure side. On the contrary, at the time of the extension operation, oil corresponding to the withdrawal volume of the piston rod 16 is sucked from the reservoir into the pressure side chamber via the check valve, and the oil in the extension side chamber flows out to the pressure side chamber via the extension side valve of the piston. The extensional damping force is generated by the flow resistance of the valve. Although the outer tube is used as the vehicle body side tube 1 and the inner tube is used as the wheel side tube 2, they are formed in an inverted type, but an upright front fork in which these are reversed may be used.

In the above-mentioned front fork, the present invention incorporates a shock absorbing mechanism for absorbing an input due to high frequency vibration. As shown in FIG. 2, a hollow adjuster 7 for adjusting the initial load of the suspension spring is rotatably inserted into the cap 4, and the damper 3 is hollow while the adjuster 7 faces the suspension spring 6. A pair of upper and lower elastic bodies 8 and 9 which are connected to the piston rod 16 and absorb a high frequency vibration input to the piston rod 16 are provided between the cap 4 and the adjuster 7.

The shock absorbing mechanism and the structure around it will be described in detail below.

The cap 4 is hollow and is screwed into the vehicle body side tube 1.

A slider 10 is screwed onto the outer circumference of the adjuster 7, a hole is formed in the outer circumference of the slider 10, and a sphere 11 is fitted in this hole. Adjuster 7
Sphere 1 fitted into the key groove 12 on the cap 4 side when rotating
The slider 10 is restricted from rotating by 1 and slides up and down. A pipe-shaped spacer 13 is interposed between the lower portion of the slider 10 and the suspension spring 6, and an initial set load of the suspension spring 6 is set by the vertical movement position of the slider 10 accompanying the rotation of the adjuster 7.

A dial 14 is screwed onto the outer periphery of the upper end of the adjuster 7 and is fixed by a lock nut 15. The dial 14 is positioned on the cap 4 via a detent mechanism 16.

The lower part of the adjuster 7 is a piston rod 16
It is screwed onto the upper end of and is fixed by a lock nut 24. A sleeve 25 is screwed onto the upper portion of the adjuster 7, and a damping force adjusting adjuster 17 inserted into the sleeve 25 is screwed onto the center of the adjuster 7 via a screw 15 so as to be movable up and down. Sphere 1 as a detent structure fitted in the groove formed in the sleeve 25
It is designed to be positioned via 9.

A control rod 18 for adjusting the damping force of the expansion valve of the piston is vertically movably inserted into the piston rod 16, and the upper end of the control rod 18 is in contact with the lower end of the adjuster 17. As a result, the adjuster 17 is operated in the vertical direction to drive the control rod 18 in the vertical direction.

Next, the shock absorbing mechanism will be described.

The main element of this mechanism is composed of a pair of upper and lower expansion side elastic bodies 8 and compression side elastic bodies 9 as described above.
These elastic bodies 8 and 9 may be composed of an elastic member 20 made of a single rubber or the like, but sliding resistance such as Teflon (registered trademark) laminated on the upper side, the lower side, or both upper and lower sides of the elastic member 20. A slide plate 21 having a small size may be provided.
When the slide plate 21 is provided, the adjuster 7
It is possible to alleviate the twisting of the elastic bodies 8 and 9 during the rotation operation, to prevent the damage, and to reduce the rotation operation resistance.

A flange 22 extending to the outer peripheral side of the adjuster 7 is provided on the inner periphery of the cap 4, while a flange 23 extending to the inner peripheral side of the cap 4 is provided on the outer periphery of the adjuster 7. Then, the upper elastic body 8 is provided with the dial 14 and the collar 2.
2 and the lower compression-side elastic body 9 is interposed between the flange 22 and the flange 23. As a result, the adjuster 7 and the piston rod 16 are floatingly connected to the cap 4 via the elastic bodies 8 and 9.

According to the above-described shock absorbing mechanism, when the vehicle passes through the road surface projections, seams, and other steps, high frequency vibration is input and compression operation is performed to cause the piston rod 16 and the adjuster 7 to move. Even when pushed up, this pushing-up force is carried by the pressure-side elastic body 9 via the flange 23, and the contraction absorbs the impact. As a result, the vibration input is prevented from propagating to the vehicle body or the steering wheel side. At this time, since the adjuster 7 moves up, the expansion side elastic body 8 expands.

When the extension operation is switched from this state, the adjuster 7 is about to descend, the expanded elastic body 8 is pressed by the dial 14 and contracts, and the compressive elastic body 9 expands to expand the elastic body 8. Since it absorbs the impact, it is possible to improve the followability to the road surface. Since the elastic bodies 8 and 9 are also opposed to the suspension spring 6, they can be opposed to the reaction force of the suspension spring 6 and the initial hardness can be relaxed even with a high preload spring characteristic.

[0028]

According to the present invention, the following effects can be obtained.

(1) According to the invention of each claim, since the elastic body for accommodating the high-frequency vibration input is provided between the adjuster and the cap, the high-frequency vibration input is passed through the protrusions while the vehicle is running. Even if it receives, the adjuster and the piston rod float, and since the elastic body absorbs the above-mentioned input, the impact does not propagate to the vehicle body and the steering wheel, and the riding comfort of the vehicle is improved.

(2) According to the second aspect of the present invention, since the upper and lower two expansion side elastic bodies and the compression side elastic body are provided as the elastic bodies, the compression side elastic body is compressed by high frequency vibration input. The extension side elastic body absorbs the impact when the input is absorbed and the extension operation is switched, so that the followability to the road surface of the vehicle is improved.

(3) According to the third aspect of the invention, since the slide plate is disposed so as to overlap the elastic body, twisting of the elastic body is alleviated when the adjuster is rotated, and damage to the elastic plate is prevented. At the same time, the rotational operation resistance of the adjuster can be reduced.

(4) Further, according to the inventions of the respective claims, since the elastic body is provided in addition to the damper, the damping force of the general damper and the shock absorption of the elastic body cooperate with each other, so that the vehicle is more effective. Ride comfort is improved.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view of a front fork according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view of FIG.

[Explanation of symbols]

1 Body side tube 2 wheel side tube 3 damper 4 cap 6 suspension springs 7 Adjuster 8,9 elastic body 14 dial 16 piston rod 21 slide plate 22,24 Tsuba 23 Flange

Claims (3)

[Claims] 1. A vehicle body side tube and a wheel side tube are slidably fitted together, a damper is erected at the center of the wheel side tube, and a suspension spring is interposed between the vehicle body side tube and the damper. In the front fork, an adjuster for adjusting the initial setting load of the suspension spring is rotatably inserted into the cap, and the adjuster is connected to the piston rod of the damper while facing the suspension spring. A front fork characterized in that an elastic body that absorbs high-frequency vibration input acting on the piston rod is provided between the front fork. 2. A dial is provided on the outer circumference of the upper end of the adjuster, a flange extending toward the inner circumference of the cap is provided on the body of the adjuster, and a flange extending toward the outer circumference of the adjuster is provided on the inner circumference of the cap. The front fork according to claim 1, wherein an extension side elastic body is provided between the flange and the compression side elastic body between the flange and the flange. 3. The slide plate is placed on the upper side, the lower side, or both upper and lower sides of each elastic body in a stacked manner.
Front fork.