JPS63192683A - Position dependency type front fork - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a position-dependent front fork for a motorcycle.

(Prior Art) A front fork in which the damping force of the front fork changes depending on the piston position of the inner tube, that is, the stroke position, is known from Japanese Patent Publication No. 58-24312. This front fork consists of an inner tube and an outer tube that are slidable relative to each other, and a seat pipe that is fixed to the bottom of the outer tube and whose upper end piston is fitted into the inner tube. A push-side damping force generator is disposed between the suspension spring and the suspension spring at the upper part of the inner tube.

In this device, a pan-shaped valve seat with an oil hole in the center is placed between a suspension spring and a piston, and a check valve that is biased by a spring to always close the oil hole is placed on the underside of this valve seat. It is made up of the following: During the push stroke, when the hydraulic pressure inside the seat pipe increases as the inner pipe descends, the valve seat is pushed up against the elasticity of the suspension spring, creating a gap between it and the piston, and the valve seat is pushed up through this gap. Oil in the seat pipe flows out to the top of the inner pipe. As the stroke of the inner tube increases, the suspension spring is compressed and its elasticity increases, and accordingly, the push-side damping force also increases linearly. However, since the push-side damping force increases linearly depending on the stroke position, the damping force becomes relatively large even with a small stroke, resulting in a hard ride. In addition, since the valve seat only rests on the top surface of the piston, its movement is uncertain, and the flow path that occurs during the pushing stroke is bent at right angles, so the oil flow is disturbed and the damping force is insufficient. It has the disadvantage that it occurs in a stable state.

(Objective of the Invention) The object of the present invention is to gradually increase the damping force according to the position of the stroke so that the damping force is very small with a small stroke and becomes considerably large with a large stroke. It is an object of the present invention to provide a position-dependent front fork equipped with a push-side damping force generating device that stably generates damping force.

(Structure of the Invention) In order to achieve the above object, according to the present invention, the push-side damping force generator is arranged in series with a position detection spring mounted on the piston and on this position detection spring. The slide member has a cylindrical slide member, a guide tube is disposed inside the slide member, the slide member has a flow path inside that linearly communicates the upper part of the inner tube and the inside of the sheet pipe, and A relief valve may be provided on the upper part of the slide member, which is slidable on the outer periphery and acts to close the flow path when the position detection spring is compressed.

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

FIG. 3 shows a longitudinal section of a front fork of a motorcycle equipped with the push-side damping force generating device of the present invention. Reference numeral 1 denotes an outer tube configured as a bottom case, the upper end of which is open, and an inner tube 2 configured as a fork pipe is slidably fitted into the outer tube 1. A seat pipe 4 having a piston 3 at its upper end is fixed to the bottom of the outer tube 1 with bolts via an oil lock piece 5. An oil hole 6 is provided at the lower end of the seat pipe 4.

An oil lock collar 8 that fits into the oil lock heath 5 at the end of the pushing stroke is attached to the lower end of the inner tube 2, and a free valve 9 having a flow path on the inner and outer surfaces is arranged above the oil lock collar 8. A radial groove is provided on the upper surface of the free valve 9. 10 indicates a rebound spring, and 11 indicates a suspension spring. A sealing mechanism 12 is attached to the upper end of the outer tube 1 to slidably seal the space between the outer tube 1 and the inner tube 2.

A push-side damping force generating device 20 according to the present invention is provided between the piston 3 of the seat pipe 4 and the suspension spring 11. Figures 1 and 2 show enlarged views.

A valve seat 22 having a plurality of passages 21 communicating with the inside of the seat pipe 4 is mounted on the upper surface of the piston 3, and a guide cylinder 23 extends from the valve seat 22 along the axis of the front fork. There is. Valve seat 2
A position detection spring 24 is disposed on the outer circumference of the guide tube 23, and a cylindrical slide member 25 is disposed above the position detection spring 24 so as to be slidable on the outer circumference of the guide tube 23 and the inner circumference of the inner tube 2. is located. As is clear from FIG. 2, a plurality of channels 26 are formed inside the slide member 25 and run in the axial direction.

A relief valve 27 is attached to the enlarged diameter part 25a at the upper part of the slide member 25, and a relief spring 29 whose upper end is supported by a spring receiver 28 placed on the upper end of the enlarged diameter part 25a of the slide member 25 serves as the relief valve. 27 is urged downward.

In this state, the flow path between the relief valve 27 and the guide cylinder 23 is always open. A set bolt 30 passing through the center of the uppermost spring receiver 28 and the lowermost valve seat 22
are tightened by a nut 31 to form one unit.

Furthermore, a flow passage 32 is provided in the area of the valve seat 22 inside the guide tube 23, and a check valve 33 is biased by a spring 34 so as to close this flow passage.

The interior of the front fork is divided into a chamber A inside the seat pipe 4, a chamber B outside, a chamber C3 between the free valve 9 of the inner tube 2 and the piston 3 of the seat pipe 4, and a chamber above the inner tube. The upper part of the chamber is filled with gas, and all other chambers below are filled with oil.

Next, the operation of the front fork push-side damping force generating device 200 configured as above will be explained.

When the inner tube 2 descends while compressing the suspension spring 11 at the end of the pushing stroke, the free valve 9 is pushed up and the oil in the B chamber flows into the C chamber without resistance through the channels on the inner and outer peripheries of the free valve 9. Then, B is equal to the volume of the inner tube 2 that has moved downward.
Oil in the room flows into the A chamber in the seat pipe 4 without resistance through the oil hole 6. At the same time, as shown in FIG. 1, the oil in chamber A within the seat pipe 4 passes upward from the flow path 21 of the valve seat 22 through the flow path 26 of the slide member 25, and further through the flow path 28a of the spring receiver 28. It flows into room D. At this time, since the suspension spring 11 is compressed, the position detection spring 24 is also compressed according to the reaction force, and the slide member 25 moves downward while being guided along the outer periphery of the guide tube 23, so that the relief valve 27 also moves downward. As it moves downward, the inner flow path gradually becomes smaller.

When the load applied to the suspension spring 11 is small and the stroke of the inner tube 2 is small, the amount of deflection of the position detection spring 24 is also small, and therefore the flow path between the relief valve 27 and the periphery of the guide tube 23 is relatively wide open. Therefore, it generates a small damping force and provides a soft ride. As the load applied to the suspension spring 11 increases and the stroke increases, the amount of deflection of the position detection spring 24 also gradually increases (as a result, the flow path between the relief valve 27 and the periphery of the guide tube 23 gradually becomes smaller). , the damping force increases gradually and generates a considerably higher damping force compared to the damping force when the stroke is small.

When the oil pressure in chamber A inside the seat vibe 4 exceeds a certain value, the relief spring 29 contracts and the relief valve 2
7 is pushed up and opens the flow path, allowing the oil in chamber A to flow upward D
Escape to the room. This prevents the push-side damping force from exceeding a certain value.

When the inner tube 2 rises during the extension stroke, the free valve 9 lowers and seats on the oil lock piece 8, so the oil in the C chamber flows downward into the B chamber through the inner flow path of the free valve 9, and at this time. This resistance generates a damping force on the rebound side. At the same time, the sheet pipe 4 is
Oil flows into chamber B from chamber A through the oil hole 6 without resistance to replenish oil. At this time, the valve seat 22
The check valve 33 provided in the chamber A is sucked downward by the negative pressure in the A chamber, opens the flow path 32, and oil is supplied from the D chamber to the A chamber in the seat pipe 4.

[Effects of the Invention] In the present invention, a push-side damping force generator disposed between a piston of a seat pipe and a suspension spring is arranged in series with a position detection spring mounted on the piston. It is composed of a cylindrical slide member, and the slide member can freely slide on the outer periphery of a guide tube arranged inside the slide member, and furthermore, a position detection spring is placed on the top of the slide member, and the position detection spring is compressed as the suspension spring is compressed during the pushing stroke. By providing a relief valve that sometimes acts to close the flow path of the slide member that communicates between the upper part of the inner pipe and the inside of the seat pipe, the damping force is very small with a small stroke and the ride is soft, and with a large stroke the damping force is very small and the ride is soft. The damping force can be increased stepwise depending on the position of the stroke so that a considerably large damping force is obtained. In addition, since the slide member slides while being guided by the outer periphery of the guide tube, its operation is reliable, and the upper part of the inner pipe and the inside of the seat pipe are communicated almost linearly inside the slide member. Since it has a flow path, there is no turbulence in the flow of oil and a stable damping force is generated.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the push-side damping force generator of the present invention for a front fork, FIG. 2 is a cross-sectional view taken along line E-H in FIG. 1, and FIG. FIG. 3 is a longitudinal cross-sectional view of a front fork equipped with a side damping force generator. l... Outer tube 2... Inner tube 3... Piston 4... Seat pipe 11... Suspension spring 20... Push side damping force generator 23... Guide cylinder 24... Position Detection spring 25...Slide member 27...Relief valve

Claims (1)

[Claims] (1) Consists of an inner tube and an outer tube that are slidable relative to each other, and a seat pipe that is fixed to the bottom of the outer tube and whose upper end piston is fitted into the inner tube. In a position-dependent front fork in which a push-side damping force generator is disposed between a suspension spring on the upper part of the tube, the push-side damping force generator includes a position detection spring mounted on the piston; It has a cylindrical slide member arranged in series on this position detection spring, and a guide tube is arranged inside this slide member, and the slide member linearly connects the upper part of the inner pipe and the inside of the seat pipe. It has a communicating flow path and is slidable on the outer periphery of the guide cylinder, and a relief valve is provided at the top of the slide member that acts to close the flow path when the position detection spring is compressed. Features a position-dependent front fork.