JPH08270710A - Front fork - Google Patents

Abstract

PURPOSE: To simplify the structure of a front fork, reduce the weight thereof, and improve the workability and assembly property thereof, by providing a cushion member opposed to the upper end of a damper cylinder in the optional position of the outer circumference of a piston rod, and arranging a part in which the coil pitch of a suspension spring coil is small, in the upper end part of the damper cylinder. CONSTITUTION: A cushion member 14 held by a stopper 12 and a snap ring 13 is arranged in the optional position of a piston rod 8, that is, approximately intermediate position thereof, and this cushion member 14 is opposed to the inner circumference of a part 5b in which a coil pitch in a suspension spring 5 is small. The part 5b having the small coil pitch consists of a tightly wrapped coil part to which a spirally coiled wire is tightly stuck. The cushion member 14 is formed of a cylindrical body formed of an elastic material such as rubber. In the vicinity of maximum compression, the cushion member 14 is penetrated inside the part 5b in which the coil pitch of the suspension spring 5 is small, so that a compression load is raised accompanying increment of deflection quantity.

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 in a vehicle such as a motorcycle and that damps vibrations from the road surface.

[0002]

2. Description of the Related Art As a front fork of this type, for example, the one disclosed in Japanese Utility Model Laid-Open No. 4-56236 is known.

In this front fork, a wheel-side inner tube is slidably inserted into a vehicle body-side outer tube, a damper is built in the outer tube and the inner tube, and a damper has a piston in a damper cylinder and a damper cylinder. It consists of a piston rod movably inserted through. Further, a hollow cylindrical oil lock case is erected on the upper end of the damper cylinder, and a cushion member facing the oil lock case is provided on the outer circumference of the piston rod, and a suspension spring is provided between the upper end of the oil lock case and the outer tube. It is installed. In the vicinity of the most compressed state, the cushion member fits into the oil lock case to effect the oil lock, and the oil lock case regulates the bulging deformation of the cushion member.

[0004]

However, the above-mentioned front fork has a complicated structure and a large number of parts because the oil lock case is erected on the upper end of the damper cylinder for the purpose of making the oil lock work. The weight becomes heavy, and the workability and assemblability are difficult, resulting in an increase in cost.

Therefore, an object of the present invention is to have a simple structure,
It is an object of the present invention to provide a front fork that can reduce the weight, improve the workability and the assembling property, and reduce the cost.

[0006]

In order to achieve the above object, the structure of the present invention is such that an inner tube is slidably inserted into an outer tube and a damper is built in the outer tube and the inner tube. Is composed of a damper cylinder connected to the inner tube side and a piston rod movably inserted into the damper cylinder via a piston and connected to the outer tube, and suspended between the upper part of the damper cylinder and the outer tube. In the front fork in which the spring is interposed, a cushion member facing the upper end of the damper cylinder is provided at an arbitrary position on the outer circumference of the piston rod, and the suspension spring is configured with a portion having a large coil pitch and a portion having a small coil pitch, Damper sill for parts with a small coil pitch It is characterized in that is disposed in the upper portion.

In this case, a portion having a small coil pitch is formed by a close-wound coil portion in which spirally wound wires are in close contact with each other, and the cushion member is formed by a cylindrical elastic material which can be fitted in the close-wound coil portion. Is preferred.

[0008]

When the cushion member approaches the inside of the portion of the suspension spring where the coil pitch is small and the lower end of the suspension member comes into contact with the upper end of the damper cylinder, the cushion member gradually bends near the maximum compression, and as the amount of deflection increases. There is no compression load and the bottomed cushion works. At this time, when the outer circumference of the cushion member comes into contact with the inner circumference of the portion having a small coil pitch, the flexure of the cushion member is restricted and the compressive load sharply increases.
More effectively absorbs bottom impact. Further, when the cushion member enters the portion with a small coil pitch and bends, the flow of oil from the outer circumference of the cushion member to the upper side is regulated, and the oil of the piston rod moving volume flowing from the lower side to the upper side is reduced in the portion with a small coil pitch. Restriction is generated in the gap between the outer circumference and the inner circumference of the inner tube, and throttling resistance occurs.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention.

The front fork includes an outer tube 1 on the vehicle body side, an inner tube 2 on the wheel side slidably inserted into the outer tube 1 on the vehicle body side, a damper 3 built in the outer tube 1 and the inner tube 2, and a damper. 3 and a suspension spring 5 provided between a spring guide 4 provided on the upper portion of the outer tube 1.

The damper 3 includes a damper cylinder 6 standing upright in the center of the inner tube 2 and a damper cylinder 6.
The piston rod 8 is movably inserted through a piston 7 having a damping force generating mechanism.

A cap 9 is provided on the upper end of the damper cylinder 6.
And a spring seat 10 having a through hole is provided on the outer circumference of the cap.
0 carries the lower end of the suspension spring 5.

The spring seat 10 may be provided directly on the outer periphery of the upper portion of the damper cylinder 6.

The through hole formed in the spring seat 10 allows the oil to flow between the upper and lower oil chambers 11 and 12 during the expansion and contraction operation.

The suspension spring 5 is composed of an upper portion 5a having a large coil pitch and a portion 5b having a small coil pitch, and the portion 5b having a small pitch is a damper 3.
It is located on the side.

The portion 5b having a small coil pitch is composed of a close-wound coil portion in which spirally wound wires are in close contact with each other.

A cushion member 14 sandwiched between a stopper 12 and a snap ring 13 is provided at an arbitrary position of the piston rod 8, that is, substantially in the middle thereof. The cushion member 14 is a portion of the suspension spring 5 having a small coil hitch 5b. It faces the inner circumference.

The cushion member 14 is formed of a cylindrical body formed of an elastic material such as rubber.

The mounting method and material of the cushion member 14 are
It is not limited to the above.

As is known, a damping force is generated in the damper 3 during the expansion and contraction operation. During the expansion and contraction operation, oil corresponding to the piston rod entry volume flows between the oil chambers 11 and 12 through the through hole provided in the spring seat 10.

Near the maximum compression, the cushion member 14 enters the inside of the portion 5b of the suspension spring 5 having a small coil pitch, and when its lower end abuts on the upper end of the damper cylinder, that is, the upper surface of the cap 9, the cushion member 14 gradually bends. As the amount of flexure increases, the compressive load increases and the bottomed cushion works. At this time, if the outer circumference of the cushion member 14 bends and swells, the cushion member 14 contacts the inner circumference of the portion 5b having a small coil pitch. Therefore, the bending load of the cushion member 14 is restricted, and the compressive load rapidly increases, so that the bottoming can be more effectively achieved. Absorbs the shock of. Further, when the cushion member 14 enters the portion 5b having a small coil pitch and bends, the flow of oil from the outer periphery of the cushion member 14 to the upper side is restricted, and the piston rod flowing from the lower oil chamber 12 to the upper oil chamber 11 flows. The moving volume of oil is regulated by the gap between the outer circumference of the portion 5b having a small coil pitch and the inner circumference of the inner tube 2, and more effective throttle resistance is generated.

The portion 5b of the suspension spring 5 having a small coil pitch, that is, the closely wound coil portion is the cushion member 14.
Since it also serves as a member for restricting the bulging deformation, it has an effect of eliminating the need to provide a member for restricting the bulging deformation.

FIG. 3 shows another embodiment of the present invention.

The suspension spring 5 is composed of a portion 5a having a large coil pitch and a lower portion 5b having a small coil pitch. The coil pitch of the portion 5b having a small coil pitch is as shown in FIG. In comparison, the lines are not in close contact with each other and are slightly apart. The action and effect are shown in Figure 1.
Is the same as

Other configurations, operations, and effects are the same as those of the front fork shown in FIG.

[0027]

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

Since the suspension spring is composed of a portion having a large coil pitch and a portion having a small coil pitch, and the portion having a small coil pitch is arranged at the upper end portion of the damper cylinder, the cushion member has a portion having a small coil pitch near the maximum compression. When the inner diameter of the cushion member comes into contact with the upper end of the damper cylinder, the bulging deformation of the outer diameter of the cushion member is restricted by the inner circumference of the portion with a small coil pitch, increasing the compressive load of the cushion member Absorbs energy.

Further, when the outer circumference of the cushion member swells and comes into contact with a portion with a small coil pitch, the oil flowing around the outer circumference of the cushion member is regulated, and the oil flowing from below to above rises between the portion with a small coil pitch and the inner tube. Flow through the gap, but this flow is throttled in this gap, throttling resistance is generated, and more effective shock absorption is achieved.

[Brief description of drawings]

FIG. 1 is a partially cutaway vertical front view of a front fork according to an embodiment of the present invention.

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

FIG. 3 is a partially enlarged sectional view of a front fork according to another embodiment.

[Explanation of symbols]

 1 Outer tube 2 Inner tube 3 Damper 5 Suspension spring 5a Large coil pitch 5b Small coil pitch 6 Damper cylinder 7 Piston 8 Piston rod 14 Cushion member

Claims (2)

[Claims] 1. An inner tube is slidably inserted into an outer tube, a damper is built in the outer tube and the inner tube, and the damper has a damper cylinder connected to the inner tube side and a piston in a damper cylinder. And a piston rod that is movably inserted and is connected to the outer tube,
In a front fork in which a suspension spring is interposed between the upper part of the damper cylinder and the outer tube, a cushion member facing the upper end of the damper cylinder is provided at an arbitrary position on the outer circumference of the piston rod, and the suspension spring has a coil pitch. A front fork comprising a large portion and a portion with a small coil pitch, and the portion with a small coil pitch is arranged at the upper end of the damper cylinder. 2. A portion having a small coil pitch is formed of a close-wound coil portion in which a spirally wound wire is in close contact, and the cushion member is formed of a tubular elastic material that can be fitted in the close-wound coil portion. The front fork according to claim 1.