JPS6185287A - Telescopic type front fork for car - 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 OBJECTS OF THE INVENTION (1) Field of Industrial Application The present invention relates to a telescopic front fork used in vehicles, primarily motorcycles and tricycles.

(2) Conventional technology Conventionally, a telescopic front fork of a motorcycle has a steering stem rotatably supported on a head pipe at the front end of the vehicle body frame, and a steering handle attached to the upper end; Upper and lower bridges are fixed to each other; a pair of left and right fork pipes are fixed to both bridges with a head pipe in between; and a pair of left and right bottom cases that slide on these fork pipes. The front wheels are supported by an axle bridged between the lower ends (for example,
8-43588).

(3) Problems to be Solved by the Invention In such conventional front forks, in order to strengthen the bending rigidity, the fork pipe and the bottom case are generally made larger in diameter. Since the case is offset from the axis of the steering stem to one side of the wheel, the above-mentioned method significantly increases the moment of inertia around the steering stem of the front fork due to the increased weight of the fork pipe and bottom case. Become.

The present invention was made in view of such circumstances, and an object of the present invention is to provide a telescopic front fork that can strengthen bending rigidity without significantly increasing the moment of inertia around the steering stem. purpose.

B0 Structure of the Invention (1) Means for Solving Problems The telescopic front fork of the present invention is rotatably supported by a head pipe at the front end of the vehicle body frame, and has a hollow steering wheel with a steering handle attached to the upper end. a stem; a guide pipe that slides into the hollow part of the stem and projects downward; a fork pipe that is fixed to the steering stem via an upper bridge that extends laterally; a fork pipe that extends laterally to the lower end of the guide pipe; It is characterized in that it consists of a bottom case that is fixedly installed via a lower bridge and slides on the fork pipe, and that the front wheel is pivotally supported at the lower end of the bottom case.

(2) Function Since the steering stem and fork pipe, as well as the guide pipe and bottom case are integrally connected via the upper and lower bridges, relative rotation is restrained. Therefore, the direction of the front wheels is linked to the rotation of the steering wheel.

The guide pipe that slides into the hollow steering stem is arranged parallel to the fork pipe to increase the bending rigidity of the front fork. Moreover, since the guide pipe occupies a position on the axis of the steering stem, it hardly increases the moment of inertia of the front fork around the steering stem.

(3) Examples Examples of the present invention will be explained below with reference to the drawings.
First, in FIGS. 1 and 2 showing the first embodiment, a head pipe 2 formed at the front end of a body frame 1 of a motorcycle M has a telescopic front fork 3.
are connected so that they can be steered freely.

The front fork 3 includes a hollow steering stem 5 rotatably supported on the head pipe 2 via a pair of upper and lower bearings 4, 4', and a guide vibro that slides into a portion of the hollow steering stem 5 and projects downward. , one fork pipe 8 is fixed to the lower end (or upper end) of the steering stem 5 via an upper bridge 1 extending laterally, and a lower bridge 9 is fixed to the lower end of the guide vibro via a lower bridge 9 extending laterally. It consists of a single bottom case 10 that is firmly fixed to the fork pipe 8 and slidably engages with the fork pipe 8, and a steering handle 11 is attached to the upper end of the steering stem 5.

A bearing bracket 8a extending toward the axis of the steering stem 5 is connected to the lower end of the bottom case 10.
The bracket 8a supports the proximal half of the axle 12 via a pair of bearings 13, 13', and the front half of the axle 12 rotatably supports the front wheel 14.

Although neither suspension springs nor shock absorbers for the front wheels 14 are shown, they are accommodated in the steering stem 5 and/or the bottom case 10 .

The front wheel 14 is arranged adjacent to the bottom case 10 directly below the guide vibro. At that time, the rim 14a of the front wheel 14 is
The center rotation plane O is arranged so as to include the axis of the steering stem 5. The hub 14b is offset to the side opposite to the bottom case 10 with respect to the central rotational plane O of the rim 14α, and is integrally connected to the rim 14α via a dish-shaped arm 14C. It is tied to the tip. By doing this, the bearing bracket 8
The support gap of the axle 12 by α is large, and the rim 1
4α, and therefore the tire 15 attached thereto is moved closer to the bottom case 10.

The brake 15 for the front wheel 14 is composed of an annular brake disc 17 and a brake caliper 18 that straddles the brake disc 11 from the inner circumference side to the left and right. The brake disc 11 has an arm portion 19 whose outer periphery protrudes toward the bottom case 10 from the outer periphery of the dish-shaped arm 14c.
The brake caliper 18 is supported by a bracket 21 fixed to the bottom case 10 so as to be slidable in the axial direction of the brake disc 17 via a pair of sliding pins 22,22. The brake caliper 18 operates upon receiving the output hydraulic pressure from the mask cylinder 23 attached to the steering handle 11, and can apply braking force to the front wheels 14 by compressing the brake disc 1γ.

Next, to explain the operation of this embodiment, when the front wheel 14 is vibrated up and down while the vehicle is running, the fork pipe 8 and the bottom case 10, as well as the steering stem 5 and the guide vibro, expand and contract each other. The vehicle is driven and the front wheels 14 are raised and lowered to alleviate and absorb the impact.

Further, the steering stem 5, fork pipe 8, guide vibro and bottom case 10 are integrally connected via the upper and lower bridges γ and 9, respectively, so that relative rotation is restrained. Therefore, by holding the steering handle 11 in the neutral position, the front wheels 14 can be kept in a straight-ahead attitude, and by turning the steering wheel 11 left and right, the front wheels 14 can be given a turning attitude accordingly. can.

Furthermore, the guide vibro which slides on the hollow steering stem 5 is arranged parallel to the fork pipe 8 to increase the bending rigidity of the front fork 3.

Furthermore, since the guide vibro occupies a position on the axis of the steering stem 5, the moment of inertia of the front fork 3 around the steering stem 5 is hardly increased.

Further, in the illustrated example, the fork pipe 8 is connected to the lower end of the steering stem 5 via the upper bridge 7, and its upper end ends at the lower end of the head pipe 2.
Even if the steering handle 11 is turned at a steep angle, there is no risk that the fork pipe 8 will interfere with equipment such as a fuel tank placed immediately after the head vibe 2.

Furthermore, only one fork pipe 8 and one bottom case 10 are disposed on one side of the front wheel 14, and the other side is left open, making it easy to attach and detach the wheel 12 and perform other maintenance. .

FIG. 3 shows a second embodiment of the invention, top.

Both ends of the lower surface bridges 1 and 9 extend in the left and right direction, and a pair of fork pipes 8 are provided at both ends of the upper bridge γ.
, 8, and a pair of bottom cases 1 at both ends of the lower bridge 9.
0 and 10 respectively, and both bottom cases 10 and 10
Except for the fact that the axle 12 is supported on both sides by
It has the same structure as the previous embodiment.

FIG. 4 also shows a specific example in which a shock absorber 24 is provided between the steering stem 5 and the guide vibro in the first and second embodiments.

A piston 2γ fixed to a rod 26 hanging from the ceiling of the steering stem 5 is slid onto the guide vibro filled with buffer oil 25, and the inside of the guide vibro is divided into an upper oil chamber 28 and a lower oil chamber 29 by this piston 2γ. It is divided into The rod 26 and the piston 21 have a series of hollow parts 30 that open into the lower oil chamber 29, and this hollow part 30 allows the upper oil to flow through a through hole 31 and an orifice 32 formed in the peripheral wall of the rod 26. It communicates with the chamber 28.

The through hole 31 is arranged directly above the piston 21, and a check valve 33 for controlling opening and closing of the through hole 31 is attached to the rod 26. The check valve 33 is configured to rise when receiving high pressure from the side of the passage hole 31 to open the passage hole 31, and to fall and close the passage hole 31 when receiving high pressure from the upper oil chamber 28 side. The upper limit of this check valve 33 is regulated by a stop ring 34 fixed to the rod 26.

Orifice 32 is located above check valve 33.

When a compressive load is applied to the front fork 3 in the vertical direction, the pressure in the lower oil chamber 29 that increases accordingly acts on the check valve 33 through the through hole 31 and opens it, so that the lower oil chamber 29 The buffer oil 25 quickly moves to the upper oil chamber 28 through the through hole 31, and as a result, the contraction operation of the front fork 3 is performed smoothly. Next, when the compressive load is removed and a tension force is applied to the front fork 3 due to the elastic force of a suspension spring (not shown), the check valve 33 is closed by the pressure in the upper oil chamber 28 that increases accordingly. , the buffer oil 25 in the upper oil chamber 28 passes through the orifice 32 and moves to the lower oil chamber 29. then,
A damping force is generated by the throttling resistance applied to the buffer oil 25 of the orifice 32, and the rapid extension movement of the front fork 3 is suppressed.

C0 Effects of the Invention As described above, the telescopic front fork of the present invention includes a hollow steering stem rotatably supported on a head pipe at the front end of the vehicle body frame, and a steering handle attached to the upper end; a guide pipe that slides on the steering stem and projects downward; a fork pipe that is fixed to the steering stem via an upper bridge that extends laterally; a fork pipe that is fixed to the lower end of the guide pipe via a lower bridge that extends laterally; Since the front wheel is pivotally supported at the lower end of the bottom case, the moment of inertia around the steering stem of the front fork is reduced by adding a guide pipe that slides on the steering stem. The bending rigidity of the front fork can be strengthened without significantly increasing the front fork.

[Brief explanation of drawings]

Fig. 1 is a side view of the front part of a motorcycle showing a first embodiment of the present invention, Fig. 2 is a longitudinal sectional front view of Fig. 1, and Fig. 3 is a front view of a motorcycle showing a second embodiment of the invention. FIG. 4 is a longitudinal sectional view showing a specific example in which a shock absorber is provided to the steering stem and guide pipe. 1...Vehicle frame, 2...Head pipe, 3...
・Front fork, 5...Steering stem, 6
...Guide pipe, γ...Upper bridge, 8...Fork pipe, 9...Lower bridge, 10...Bottom case, 11...Steering handle, 12...Axle,
14... Front wheel patent applicant Honda Motor Co., Ltd. Figure 3 1J opening 361-tFZ6'/ (0) Figure 4

Claims (1)

[Claims] A hollow steering stem rotatably supported by a head pipe at the front end of the vehicle body frame and having a steering handle attached to its upper end; a guide pipe that slides into the hollow part of the stem and projects downward; It consists of a fork pipe fixedly installed via an upper bridge extending laterally; a bottom case fixedly attached to the lower end of the guide pipe via a lower bridge extending laterally and slidingly mating with the fork pipe; A vehicle's telescopic front fork that pivots the front wheel at its lower end.