JPH069995B2 - Front wheel shock absorber for motorcycles - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of a front wheel shock absorber for a motorcycle.

(Prior Art) In a front wheel shock absorber for a two-wheeled vehicle equipped with a so-called telescopic type front fork in which inner and outer tubular members are elastically fitted with a spring interposed, a shock from the road surface causes a shock to the front fork. Although it absorbs as it expands and contracts, the front forks that are arranged at an angle cause friction between the inner and outer cylinders due to the component force that is orthogonal to the direction of expansion and contraction.
This friction is large at the initial stage of sliding of the outer cylinder, and if the load acting on the front fork is equal to or less than the initial friction, the cushioning operation is not performed and there is a problem that the riding comfort is reduced.

In order to improve such a problem, a shock absorber as shown in FIG. 5 is disclosed in Japanese Patent Publication No. 57-49432. This will be described below.

Reference numeral 1 denotes a front fork supporting a front wheel. The front fork 1 has a built-in hydraulic shock absorbing mechanism, and is provided with an outer tube 2 which is an outer tubular member and an inner tube 3 which is an inner tubular member which are fitted to each other. It is configured to be stretchable in any direction. The front fork 1 is installed so as to be inclined due to the relationship between the caster and the trail, and the upper end of the inner tube 3 is coupled to the head chews 6 of the vehicle body frame 5 via the upper and lower brackets 4 and 4, and the steering handle 7 is mounted on the bracket 4. Is provided.

One end of a link 10 is pivotally attached to the lower end of the outer tube 2 via a pin portion 11, and a sub-cushion unit 12 is vertically arranged between the outer tube 2 and the other end of the link 10 extending substantially horizontally toward the rear. Placed and link 10
The axle 9 is coupled to the substantially central portion of the.

In the sub-cushion unit 12, a rod 13 is connected to one end of a link 10 via a pin 14, and a cylindrical body 15 slidably accommodating a piston 16 connected to the rod 13 is a rear surface of an intermediate portion of the outer tube 2. It is connected to the bracket 2a protruding from the. Inside the cylindrical body 15, a cone-shaped cushion rubber 17 that contacts the upper surface of the piston 16 is provided.
And a donut-shaped stopper rubber 18 that contacts the lower surface of the piston 16.

In the initial stage of a large load of the initial friction of the front fork 1, the sub-cushion unit 12 is expanded and contracted, and the wheels 8 are pivoted about the lower end of the front fork 1 as a fulcrum to perform a buffering operation. 1 will expand and contract.

Therefore, the effective and appropriate cushioning operation is performed from the initial load to the entire load range, and the riding comfort can be improved.

(Problems to be Solved by the Invention) In such a shock absorber, the cushion rubber 17 of the sub-cushion unit 12 is compressed via the link 10 by the increased load of the front wheels at the time of braking, and the link 10 becomes Since it rotates counterclockwise about 9
As a result, the operating point T on the extension of the front fork approaches the ground contact point H side, and there is a problem that the straight traveling performance is deteriorated due to the reduction of the trail.

Therefore, an object of the present invention is to suppress the reduction of the trail during braking, reduce the nose dive, and improve the maneuverability during braking.

(Means for Solving Problems) Therefore, according to the present invention, an L-shaped link is rotatably attached to the lower end of the front fork with its intermediate portion as a fulcrum, and is attached to the horizontal end portion of the link extending forward from the lower surface of the front fork. While supporting the axle and attaching a brake braking torque support to the standing end of the link that rises along the rear side surface of the front fork, an elastic body is interposed between the link and the lower surface and side surface of the front fork. To do.

(Operation) During braking, the link receives the brake braking torque and rotates, pushing up the lower end of the front fork with the axle as the fulcrum, which reduces the nose dive and also moves the axle relatively rearward. Reduction is suppressed. As a result, the maneuverability during braking is significantly improved.

(Embodiment) Referring to FIGS. 1 and 2, a bracket 22 extending obliquely rearward and downward is formed at a lower end portion of an outer tube 21 of a front fork 20, and an L-shaped link 24 is attached to the bracket 22 via a pin 23. Connect freely.

The link 24 supports the axle 25 at a horizontal end portion 24A that extends substantially horizontally forward on the lower surface of the outer tube 21, while the brake caliper 26 is provided at a standing end portion 24B that extends obliquely upward along the rear side surface of the outer tube 21. It is attached to the brake disc 27 in a predetermined positional relationship.
Reference numerals 26A and 26B are caliper mounting holes.

Then, the horizontal link end 24A and the outer tube 21
Compression rubber 28 is provided between the lower surface and bump rubbers 29 and 30 between the link standing end 24B and the side surface of the outer tube 21. The bump rubbers 29 and 30 are arranged at different distances from the pin 23 (link support shaft). Normally, the bump rubber 29 alone softly buffers the reband of the wheel, and the bump rubber 29 is used when jumping. And 30 is designed to absorb high loads.

Reference numeral 31 denotes a well-known anti-nose type mechanism that regulates the flow of the hydraulic oil on the pressure side of the front fork 20 during braking, and suppresses the sinking.

In the initial stage of the action of the pressure side load such as when riding on a projection on the road surface on a bad road while the motorcycle is running, the front fork 20 functions as a rigid body due to the friction between the inner and outer cylinders, and the link 24 is centered around the pin 23. By rotating counterclockwise, the compression rubber 28 is compressed between the compression rubber 28 and the lower surface of the bottom case 21 and effectively and properly cushions the initial load.

The compression rubber 2 after the buffering operation in the initial stage of the load in the range where the initial friction of the front fork 20 is large.
8 acts as a stopper at the stroke limit thereof, and when the front friction of the front fork 20 exceeds the initial friction range, the inner and outer cylinders start to contract in the axial direction to perform a buffering action.

Further, clockwise rotation in the figure is restricted by the bump rubbers 29 and 30 that are interposed between the link 24 and the side surface of the outer tube 21, and thereby the followability to the extension side of the front fork is enhanced and the front wheel Maintain good landing conditions after bounce.

On the other hand, during braking, the anti-nose dive mechanism 31 suppresses the sinking of the front fork 20, while the link 24
Receives the braking torque acting on the brake caliper 26 and rotates in the clockwise direction in the figure, whereby the axle 25 moves relative to the pin 23 from the point a to the point b. The nose dive reduction amount n is obtained.

That is, when the rotation of the link 24 in the clockwise direction causes the axle 25 to move from the point a to the point b with the pin 23 as a fulcrum, it can be divided into horizontal displacement and vertical displacement. Indicates that the front fork 20 is relatively pushed upward by n because it cannot actually be displaced in the vertical direction. This push-up corrects the amount of sinking that occurs with braking and suppresses the nose dive. Exert.

Further, in the horizontal direction, the axle 25 is relatively displaced rearward with respect to the axis of the front fork 20 by l, so that the trail (the point where the extension of the axis of the front fork intersects the road surface and the perpendicular of the axle 25). It acts in a direction in which the distance from the point where the road surface intersects) increases, and the straightness during braking is maintained well.

Since the compression rubber 28 has the seat portion 32 slidably fitted in the guide hole 33 of the link 24, the initial load can be adjusted by the adjusting bolt 34 according to the usage conditions.

In FIG. 3, the axle 25 is located on the center line of the front fork 20 in the embodiment shown in FIG. 3, which is a layout with a so-called center axle tendency. On the other hand, in order to improve straight running, the attachment position of the axle 25 is set to the front. The rear of the fork 20 is offset to give a trailing axle-oriented layout.

Further, FIG. 3 exemplifies a case where the present invention is applied to a drum brake, and in this case, the link 24 is provided with a stopper 35 for restricting rotation of a brake shoe (not shown) of the drum brake. Different from the brake embodiment. It should be noted that only one bump rubber 29 may be provided on the side surface of the front fork 20 in terms of layout.

(Effects of the Invention) In summary, according to the present invention, the L-shaped link is rotatably attached to the lower end of the front fork with its middle portion as a fulcrum, and the axle is attached to the horizontal end of the link extending forward from the lower surface of the front fork. While supporting and attaching the brake braking torque support to the standing end of the link that rises along the rear side surface of the front fork, elastic bodies are respectively interposed between the link and the lower surface and side surface of the front fork. In addition, it is possible to suppress the depression at the time of braking to improve the maneuverability and to correct the change in the trail to maintain good straight running performance.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a partially cutaway side view of the same, FIG. 3 is a partially cutaway side view of another embodiment, and FIG. 4 is a configuration showing a conventional technique. It is a figure. 20 ... Front fork, 21 ... Outer tube, 23 ... Pin, 24 ... L-shaped link, 25 ... Axle, 26 ... Brake caliper, 26 ... Brake disc, 28 ... Compression rubber, 29, 30 …
... bump rubber.

Claims (1)

[Claims] 1. An L-shaped link is rotatably attached to a lower end of a front fork about an intermediate portion thereof as a fulcrum, an axle is supported on a substantially horizontal end of a link extending forward from a lower surface of the front fork, and a front fork is provided. While a brake braking torque supporting portion is attached to the standing end portion of the link that rises along the rear side surface, an elastic body is interposed between the link and the lower surface and the side surface of the front fork. Front wheel shock absorber.