JPS60199779A - Front fork for motorcycle, etc. - 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 Industrial Application" This invention relates to a front fork for an automatic vehicle, such as a one-wheeled vehicle, that is, a vehicle having a single front wheel.

"Prior Art and Background" Front forks are widely used as front wheel suspension systems for motorcycles, and some front forks are called dual-tube type.

This dual-tube front fork has a buffer spring interposed between the inner and outer cylinders that are telescopically fitted together, a cylinder inside the outer cylinder, and a piston held in the inner cylinder via a rod. 2. by these cylinders and pistons. It forms a heavy pressure attenuator (
For example, Utility Model Publication No. 52-U θ4 (Publication No. 6&).

As mentioned above, this type of twin-tube 70-ton fork has a structure in which the piston is held by a rod, so the 4i point is that the damping force generated can be directly adjusted by providing an ASW that passes through the rod. be.

However, in a dual-tube front fork, the outer cylinder, which is a large component, is unsprung and supports the front wheel, so the unsprung weight is relatively large, which is disadvantageous in terms of the front wheel's ability to follow the road surface. be.

In order to eliminate this disadvantage, it is conceivable to arrange the outer cylinder at the top and the inner cylinder at the bottom, but such an arrangement is not adopted in the a-opening front fork.

As a result of intensive study on this point, the inventor came to the conclusion that the reason why such an arrangement is not adopted is to ensure the lubricity of the oil seal portion.

"Purpose of the invention" This invention was made in view of the above circumstances.
By solving the above-mentioned oil seal problem, it is possible to arrange the front fork with the outer cylinder on top and the inner cylinder on the bottom, which has a large engagement capacity, and improves the front wheel's ability to follow the road surface. The purpose is to provide a fork.

"Structure of the Invention" In a structure in which an outer cylinder and an inner cylinder are configured to be extendable and retractable, the outer cylinder is fitted into the inner cylinder from above, and the upper and lower parts of the inner cylinder are held by the main part of the outer cylinder. Inside, the piston is held by a piston port extending downward from the upper bottom of the outer cylinder, and on the other hand, a cylinder extending upward from the lower bottom is provided in the inner cylinder, and the piston is reciprocated within this cylinder. At the same time, an oil seal is installed at the bottom of the outer cylinder to make the opening to the outer surface of the inner cylinder oil-tight, and the outer cylinder is filled with hydraulic oil to a point above the top of the inner cylinder. In general, the hydraulic oil, the reservoir and the space above it are used as a gas chamber,
This purpose is achieved by providing a hydraulic oil passage that communicates the IJ71 oil reservoir with the oil chamber above the piston in the cylinder, and communicates this oil reservoir with the oil chamber below the piston. I can do it.

"Embodiment" An embodiment of an automatic unit will be described below with reference to figures.

Reference numeral 1 denotes a steering shaft tube, which is provided at the front end of the motorcycle body. 2 is the front wheel, and 3 is the front fork. The 70-ton fork 3 is provided parallel to both sides of the front wheel 2.
The front wheel 2 is rotatably supported at the lower part of the front fork 3 via an axle 4 which is installed between the front forks 3 on both sides. Further, the front fork 3 is connected to each other at its upper part via an upper bracket 5 and a lower bracket 6, and has a steering shaft (1a) connecting the upper and lower brackets 5.6 in the steering shaft tube 1. The front wheels 2 are centrally operated by a steering handle 7.

The schematic structure of the front fork 3 is as shown in Fig. 2. 011 is an outer cylinder, 12 is an inner cylinder, and these are telescopically fitted to the telescopic tube. The front fork 3 is filled with hydraulic oil 0 and an inert gas G such as air. A cylinder 13 is erected in the upper half of the inner cylinder 12, a piston rod 14 is provided from the upper bottom of the outer cylinder 11, and a piston 15 is attached to the tip of the piston rod 14. This piston 15 is fitted into the cylinder 13 to constitute a piston-tortoise cylinder mechanism.

The piston 15 is provided with a disc pulp 16, which is designed to generate different damping forces during compression and expansion of the front fork 3.

Further, a first damping force adjustment device is provided in which a variable orifice 17 is provided in parallel to the disk pulp 16 provided on the piston 15, thereby making it possible to adjust the damping force generated by the expansion and contraction movement of the front fork. This first damping force adjustment device includes an oil passage 18 that communicates between the oil chambers on both end surfaces of the piston 15, a variable orifice 17 configured by disposing a needle valve 19 in the oil passage &S 18, and the needle. An operating rod #t21 that supports the back of the valve 19 is provided. The upper end of this operating rod 21 is connected to a nut 2 screwed onto the piston rod 14 at the upper end of the piston rod 14.
2 is supported by the bin 23 supported by the bottle 23.

This pin 23 is provided through an axial notch provided at the upper end of the piston rod 14, and is not fixed to the nut 22, but is only supported under pressure by a spring 24 at all times, so that the nut 22 cannot be screwed in. Bin 2 depending on quantity
3 moves back and forth in the axial direction of the piston rod 14, and as a result, the position of the needle valve 19 also moves back and forth, and the opening area of the variable orifice 17 is adjusted, thereby adjusting the damping force generated in the piston portion.

By the way, the following buffer spring force adjustment device is also provided at the upper bottom part of this outer cylinder 11.
5 is interposed between a spring receiver 26 provided at the upper end of the inner cylinder 12 and a movable spring receiver 27 provided directly below the upper bottom of the outer cylinder 11. The movable spring receiver 27 is provided so as to be slidable in the axial direction along the piston rod 14 using the inner surfaces of the piston rod 14 and the outer cylinder 11 as guide surfaces. This movable spring receiver 27 is connected to the upper bottom surface of the outer cylinder 11 or to an adjustment bin 32 (described later).
The back is supported by.

That is, the upper bottom of the outer cylinder 11 is constituted by an end fitting 28, and a large diameter blind hole with a screw is formed in the upper surface of the end fitting 28, into which an adjusting screw 29 is screwed. There is.

An annular plate 31 is provided on the bottom surface of this adjustment screw 29.
．． The upper end of the adjustment bin 32 is brought into contact with the upper end thereof. The adjustment bins 32 are arranged at three equal intervals in the circumferential direction (only seven are shown in the drawing), and the adjustment bins 32 pass through the bottom of a blind hole in the end fitting, and the lower end is a movable spring receiver. 27
Therefore, the position of the movable spring receiver 27 can be changed depending on the screwing amount of the adjustment screw 29, and the spring force of the buffer spring 25 can be adjusted.

In this embodiment, such an M-balanced spring force adjustment structure is adopted in order to handle the damping force adjustment performed by the first damping force adjustment device and the buffer spring force adjustment completely independently. .

Incidentally, 33 is a resin layer, which is made of, for example, nylon and suppresses the generation of metal fine powder.

Furthermore, this embodiment is provided with the following damping force adjusting device. As the front fork 3 expands and contracts, the volume of the piston rod 14 that occupies within the cylinder 13 changes, so the hydraulic oil corresponding to this variation will flow inside and outside the cylinder 13. is provided to generate a damping force here as well. This base valve 35 mainly generates a damping force against the flow of hydraulic oil flowing out from inside the cylinder 13 when the front fork 3 is compressed, and when the front fork 3 is compressed, it communicates with a large opening area and creates negative pressure inside the cylinder. It is designed not to. This base pulp 35 is provided with an adjusting device configured as follows, and the front fork 3
The damping force generated during the compression operation can be adjusted.

36 is the pulp body, the main passage 37 and the secondary oil! 38 communicate with both sides of this pulp body 36. and,
Plate valves 711 and 42 are installed on both end faces of the pulp body 36 to act as spring triggers.

A small hole 43 is provided in the center of the plate valve 41, and hydraulic oil flows into the main passage 37 through this small hole 43 during compression operation of the front fork. The lower end of the main passage 3 is resiliently closed by a plate valve 42, but the plate valve 42 is displaced in response to the oil pressure in the main passage 37, and the hydraulic oil flows out of the cylinder 13 (in the figure). Arrow ^). The opening created by the displacement of the plate valve 42 functions as an orifice that generates a damping force during the compression operation of the front 7 oak.

On the other hand, when the 70 ton 7 oak 3 is extended, the oil pressure outside the cylinder 13 is applied to the base valve 35u! :Top cylinder 1
The hydraulic oil is higher than the oil pressure in cylinder 13, so the hydraulic oil is
From the outside, the pulp passes through a plurality of wound passages 38 provided in the pulp body 36 to directly below the plate valve 41, opens the plate valve 41 wide due to the pressure difference, and flows into the cylinder 113. (Arrow B in the figure) By the way, the resilient force of the plate valve 42 is applied by the spring 44, and the spring receiver 45 at the other end of this spring
Has O Rad 46 installed in series, and this mouth? The lower end of the door 46 is supported by a pin 47. And this bottle 47
The negative side thereof is supported by the circumferential surface of an eccentric recess formed on the inner surface of the operating element 48. Therefore, by setting this operator 48 to the encyclical position, the O-rad 46 can be adjusted up and down, and by changing the pressing force of the plate valve 42 of the spring 44, the damping force during the compression operation of the front fork can be adjusted. Make adjustments.

In order to prevent the rotational displacement position of the operator 48 from changing unnecessarily during use, a recess 49 is formed on the outer peripheral surface of the operator 48, and a steel ball 51 is pressed elastically into this recess 49 for positioning. It is carried out. In this front fork 3, as described above, the inner cylinder 12 communicates with the inside of the cylinder 13.
The annular chamber between the inner surface of the cylinder 13 and the outer surface of the cylinder 13 (corresponding to the hydraulic oil passage in the present invention) is formed by filling the upper part of the inner cylinder 12 with an insulator X at the upper end of the inner cylinder 12. vJ oil eyebrows 9
and the cylinder 1 above the piston 15.
The oil chamber in 3 is also communicated with this hydraulic oil pump 9.

Therefore, this hydraulic oil layer 9 functions to adjust the fluctuation in the amount of hydraulic oil within the cylinder 13. Furthermore, the hydraulic oil stored in this hydraulic oil reservoir is distributed between the outer surface of the inner cylinder 12 and the bearing, spacer, and linear pole bearing 52 provided in the outer cylinder.
Oil seal 6 provided at the lower end of the inner surface of the outer cylinder via F”f.
0, the oil seal 60 can be operated with lubrication, and a dual-tube type 70-ton fork can be arranged with the outer cylinder 11 on the upper side.

Therefore, the dual-tube front fork has a light unsprung weight, which improves the road followability of the front wheels.

"Effects of the Invention" As explained above, the present invention has an outer cylinder and an inner cylinder configured to be extendable and retractable, in which the outer cylinder is fitted into the inner cylinder from above, and the upper part of the inner cylinder is connected to the lower part of the outer cylinder. In addition to maintaining the time, the piston is held in the outer cylinder by a piston rod extending downward from the upper bottom of the outer cylinder, and on the other hand, a cylinder extending upward from the lower bottom is installed in the inner cylinder to hold the piston. The piston is reciprocally movable inside the outer cylinder, and an oil seal is provided in the lower part of the outer cylinder to make the area on the outer surface of the inner cylinder oil-tight, and the oil seal is provided in the outer cylinder above the upper end of the inner cylinder. The hydraulic oil layer is filled with hydraulic oil up to this position, and the space above it is made into a gas chamber, and this hydraulic oil layer communicates with the oil chamber above the piston in the cylinder, and this oil reservoir is connected to the oil chamber above the piston. A hydraulic oil passage is provided to communicate with the

Therefore, the hydraulic oil reaches the oil seal provided at the lower end of the outer cylinder, which solves the lubrication problem in this area. The purpose of the present invention is to provide a dual-tube front fork that can be arranged in such a way as to improve the road surface followability of the front wheel.

[Brief explanation of drawings]

The drawings relate to an embodiment of the present invention for a motor vehicle or a two-wheeled motor vehicle. FIG. 1 is a front side view of the two-wheeled motor vehicle, FIGS. 2 and 2 are front views of the entire front fork, and FIG. 1 is an explanatory diagram of the base pulp adjusting device of the front fork, and FIG. 5 is a view taken in the direction of the V arrow in FIG. 1. 11...Outer cylinder 12...Inner cylinder 13...Cylinder 14-ri (I piston rod 15...Piston 60...Oil seal Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

[Claims] In a structure in which the outer cylinder and the inner cylinder are configured to be extendable and retractable, the outer cylinder is fitted into the inner cylinder from above, the upper part of the inner cylinder is held at the lower part of the outer cylinder, and the upper part of the inner cylinder is held in the lower part of the outer cylinder. The piston is held by a piston rod extending downward from the upper bottom of the outer cylinder, and a cylinder extending upward from the lower bottom is installed in the inner cylinder, so that the piston can reciprocate within this cylinder. In addition, an oil seal is installed at the bottom of the outer cylinder to make the opening on the outer surface of the inner cylinder oil-tight, and the outer cylinder is filled with hydraulic oil to a point above the top of the inner cylinder. The hydraulic oil 51 and the space above it are used as gas chambers, and this hydraulic oil reservoir communicates with an oil chamber above the piston in the cylinder, and a hydraulic oil passage communicates this oil reservoir with an oil chamber below the piston. Please set up