JPH069996B2 - 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 tube 6 of the vehicle body frame 5 via the upper and lower brackets 4, 4, and the steering wheel 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. A conical compression rubber 17 that contacts the upper surface of the piston 16 and a donut-shaped bump rubber 18 that contacts the lower surface of the piston 16 are provided inside the cylindrical body 15.

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

(Problems to be Solved by the Invention) In such a shock absorber, the compression rubber 17 of the sub-cushion unit 12 is compressed via the link 10 by the front wheel increasing load during braking.
Since the link 10 rotates counterclockwise about the axle 9, the action point T on the extension of the front fork approaches the ground contact point H side by that amount, and the reduction of the trail deteriorates the straight running performance. was there.

Further, the sub-cushion unit 12 has a complicated structure, and an anti-nose dive mechanism, a support portion for brake braking torque, and the like are arranged on the lower side surface of the front fork.

Therefore, the present invention suppresses the trail change during braking and the sinking of the front fork (nose dive) to improve the maneuverability during braking, and eliminates the buffering failure due to the initial friction with a simple structure. A purpose is to provide a front wheel shock absorber for a motorcycle.

(Means for Solving the 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.
While supporting the axle on the horizontal part of the link extending forward from the lower surface of the front fork, the elastic body for the compression side load and the elastic body for the extension side load are coaxially arranged by sandwiching the horizontal part of the link on the lower surface of the front fork. A support portion for the brake braking torque is provided at the standing portion of the link that rises along the rear side surface of the front fork.

(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 to suppress the nose dive and move the axle relatively rearward with respect to the front fork. Therefore, the change in the trail is also suppressed, and thereby the maneuverability during braking is significantly improved.

Further, since the elastic body for the compression side load and the elastic body for the extension side load are compactly arranged coaxially by sandwiching the link horizontal portion on the lower surface of the front fork, not on the side surface of the lower portion of the front fork, the configuration is simplified, The arrangement and layout of the anti-nose dive mechanism and the braking / braking torque support are also easy.

(Embodiment) In FIG. 1, a bracket 2 extending obliquely rearward and downward is provided at a lower end portion of an outer tube 21 of a front fork 20.
2 is formed, and an L-shaped link 24 is rotatably connected to the bracket 22 via a pin 23.

The link 24 supports the axle 25 with a horizontal portion 24A that extends substantially horizontally forward on the lower surface of the outer tube 21, and at the end of the link horizontal portion 24A, the front fork 20 is provided.
A flange 26 that is substantially parallel to the lower surface is formed.

Then, a compression rubber 27 that cushions the pressure side load by sandwiching the flange 26 and a bump rubber 28 that cushions the extension side load are coaxially arranged, and these are mounted by a mounting bolt 29.
Is attached to the lower surface of the front fork 20. In addition,
The inner periphery of the bolt insertion hole 30 of the flange 26 is formed in a hyperbolic shape so as not to come into contact with the bolt 29 at the time of a cushioning operation described later.

Further, the link 24 has a brake caliper (not shown) attached to a standing portion 24B extending obliquely along the rear side surface of the outer tube 21 in a predetermined positional relationship with respect to the brake disc on the axle side. Reference numerals 31A and 31B denote caliper mounting holes, and 32 denotes an anti-nose dive mechanism that regulates the flow of the hydraulic fluid on the pressure side of the front fork 20 during braking and prevents 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 27 is compressed between the lower surface of the outer tube 21 and the outer tube 21 to effectively and properly absorb 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.
7 acts as a stopper in its stroke limit, and when the front friction of the front fork 20 exceeds the range of the initial friction, the inner and outer cylinders start to contract in the axial direction to perform a cushioning action.

Also, the clockwise rotation of the link 24 is restricted by the bump rubber 28 interposed between the flange 26 and the mounting bolt 29, whereby 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 32 prevents the front fork 20 from sinking, while the link 24
Receives the braking torque acting on the brake caliper and rotates in the clockwise direction in the figure, and pushes up the lower end of the front fork 20 with the axle 25 as a fulcrum. Since it is moved rearward relative to, the trail change is also corrected.

By the way, according to this embodiment, the compression rubber 27 and the bump rubber 28 are coaxially arranged by sandwiching the flange 26, and they are attached to the lower surface of the front fork 20 by the bolts 29. Since the number of parts is small, the structure is simple and the cost is advantageous, and the compression rubber 27 and the bump rubber 28 are compactly assembled on the lower surface of the front fork 20, so that the anti-nose dive mechanism 32 and the brake caliper can be installed. Arrangement and layout are also easy.

FIG. 2 shows another embodiment in which the degree of freedom in setting the impact absorption characteristics with respect to the pressure side load is increased. A guide hole 36 for slidably supporting the seat portion 35 of the compression rubber 27 for a predetermined stroke is formed on the lower surface of the front fork 20, and a coil spring 37 is interposed between the bottom wall of the guide hole 36 and the seat portion 35.

Then, in the initial stage of the action of the pressure side load, the compression rubber 27 and the coil spring 37 absorb the impact until the displacement amount of the seat portion 35 becomes S, and when the seat portion 35 hits the bottom wall of the guide hole 36, only the compression rubber 27 is applied. Absorbs and relaxes large loads.

According to this, the impact absorption characteristic of the pressure side load can be easily and accurately set by the initial load and the spring constant of the coil spring 37 when setting the impact absorption characteristic in relation to the initial friction of the front fork 20.

(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 the intermediate portion as a fulcrum, and the axle is attached to the horizontal portion of the link extending forward from the lower surface of the front fork. While supporting and arranging the elastic body for the compression side load and the elastic body for the extension side load by sandwiching the horizontal link part on the lower surface of the front fork,
Since a support part for the brake braking torque is provided at the standing part of the link that rises along the rear side of the front fork, it suppresses the sinking during braking to improve maneuverability and corrects the trail change and travels straight ahead. It is possible to maintain good sex.

In addition, it is possible to obtain an effect that the structure of the buffer mechanism that absorbs an input load equal to or less than the initial friction of the front fork is simple and advantageous in terms of cost and mounting space.

[Brief description of drawings]

FIG. 1 is a partial sectional side view showing an embodiment of the present invention, and FIG.
FIG. 3 is a sectional view of a main part showing another embodiment, and FIG. 3 is a configuration diagram showing a conventional technique. 20 …… Front fork, 23 …… Pin, 24 …… L
V-shaped link, 25 ... axle, 27 ... compression rubber, 28 ... bump rubber, 31A, 31B ... caliper mounting holes.

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 to support an axle on a horizontal portion of the link extending from a lower surface of the front fork to a lower surface of the front fork. The elastic body for the compression side load and the elastic body for the extension side load are arranged coaxially by sandwiching the horizontal part of the link, while a support part for the brake braking torque is provided at the standing part of the link rising along the rear side surface of the front fork. A front wheel shock absorber for a two-wheeled vehicle.