JPS5996009A - Cylinder type hydraulic damper for front wheel suspension - Google Patents

Abstract

PURPOSE:To enhance the followability of a front wheel with respect to a road surface upon braking, in a suspension device by which the sinking, upon braking, of the front part of a vehicle is reduced, by providing a damping force adjusting mechanism for decreasing damping force upon extension in association with an increase in braking force of the front wheel. CONSTITUTION:Upon normal running since the open degree of a restrictor valve 70 which is opened and closed by means of a lever 72 and a control rod 68, is constructed, a fork 26 is compressed when the front wheel of a motor-cycle runs on an obstacle, so that oil in a second oil chamber 52 flows into a first oil chamber 50 through a valve in a piston 48. Meanwhile, a lever 72 is rotated in association with the operation of front wheel braking when a front wheel brake is effected, and therefore, the open degree of a restrictor valve 70 is increased by means of a control rod 68. Accordingly, upon extension of the fork 26 the flow resistance of oil flowing from the first oil chamber 50 to the second oil chamber 52 through the above-mentioned valve 70, is decreased to decrease the damping force upon extension, so that damping force upon extension is made small. Therefore, upon front-wheel braking the front wheel satisfactorily follows the fine recesses in the road surface so that the fork is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylindrical hydraulic damper used in front wheel suspension systems of motorcycles, automobiles, etc., and particularly relates to a damper designed to reduce sinking of the front part of the vehicle body during braking. be.

In motorcycles, the front of the vehicle sinks (dives) when braking. If the amount of sinking of the vehicle body becomes excessive, it not only deteriorates the riding comfort but also adversely affects the steering stability.

Therefore, various devices (anti-dive devices) have been proposed to restrict the dive of the front part of the vehicle body during braking. However, all of the conventional systems increase the damping force of the front wheel suspension system during braking, especially the compression damping force.

During braking, the damper suddenly becomes "hard" and cannot sufficiently absorb vibrations from the road surface, resulting in poor ride comfort.

There is also the problem that if the damper suddenly becomes "hard", the front wheels' ability to follow the road deteriorates, and the front wheels' grip on the road becomes uncertain.

This invention was made in consideration of these circumstances.
A tube for front wheel suspension that effectively prevents the vehicle body from diving without deteriorating the ride quality due to the inability to sufficiently absorb vibrations from the road surface during braking, and without deteriorating the front wheels' ability to follow the road surface. The purpose is to provide a type hydraulic damper.

In order to achieve this object, the present invention provides a cylindrical hydraulic damper for front wheel suspension in which extensional damping force is adjustable, including a damping force adjustment mechanism that reduces the extensional damping force in accordance with an increase in front wheel braking force. It is something.

The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is a plan view showing the vicinity of the upper end of the front fork, and FIG. 3 is a sectional view of the front fork.

In FIG. 1, reference numeral 10 denotes a frame, which has a steering head 12 at its front end.

14 is attached to this frame 10, ]6
is the fuel tank, 18 is the seat, and 20 is this frame 10.
The rear arm is attached to the rear arm so that it can swing up and down. A rear wheel 22 is attached to the rear end of this rear arm 20. 24 is a suspension unit that elastically supports the rear wheel 22.

Reference numeral 26 denotes a pair of left and right front forks, the upper end portions of which are attached to the head nob 4 rib 12 via an upper bracket 28 and a lower bracket 30 so as to be rotatable left and right. That is, upper and lower plugs 28 and 30 are fixed to the upper and lower ends of the steering shaft 32 (FIG. 2) that is inserted through the head 4 iso 12. 34 is a front wheel attached to the lower end of the front fork 26.

A cylindrical hydraulic damper 36 and a buffer spring 38 are incorporated into the front fork 26. In FIG. 3, 40 is an inner cylinder, and 42 is an outer cylinder, and the upper part of the inner cylinder 40 is fixed to the bracket 28, 30 so that the outer cylinder 42 is positioned below (see FIG. 1).

A cylinder 44 is fixed to the inner bottom of the outer cylinder 42, and a piston rod 46 that enters the cylinder 44 is fixed to the inner cylinder 40. 48 is a piston attached to this rod 46 and sliding inside the cylinder 44;
A first oil chamber 50 is provided in the cylinder 44 by this piston 48.
A second oil chamber 52 is defined. This piston 48 has two
These valves provide weak flow resistance to the oil when the oil flows from the first oil chamber to the second oil chamber (in the direction of the solid line arrow in Figure 3), and when the oil flows in the opposite direction (in the direction of the broken line arrow). ) provides strong flow resistance to the oil. A push-off prevention spring 54 is provided in the first oil chamber 50.
is installed.

A base knob 56 is attached to the bottom of the cylinder 44, and a third oil chamber 58 is defined below the second oil chamber 52. Two types of valves are attached to this pace valve 56, and when oil flows from the second oil chamber to the third oil chamber (
It provides strong flow resistance to the oil when flowing in the direction of the solid line arrow), and weak flow resistance when flowing in the opposite direction (in the direction of the broken line). The inside of the cylinder 44 and the lower part of the outer cylinder 42 are filled with oil, and the third oil chamber 58 communicates with the lower part of the outer cylinder 42 through a hole 60. The inside of the inner cylinder 40 and the upper part of the outer cylinder 42 are filled with air. The buffer spring 38 is mounted between a spring seat 62 provided at the upper end of the cylinder 44 and a gear 4 provided at the upper end of the inner cylinder 40.

Next, the damping force adjustment mechanism will be explained. An oil passage 66 that communicates the first oil chamber 50 and the second oil chamber 52 is formed at the tip of the piston rod 46 . A control rod 68 is inserted into the piston rod 46, and its lower end faces the oil passage 66 to form a throttle valve 70, and its upper end passes through the cap 64 and projects to the outside. A lever 72 is fixed to the protruding end of the control rod 68. This lever 72 is connected to the cap 64 by screw means 74, and when the lever 72 is rotated, the lever 72 is connected to the cap 64 by the screw means 74.
The control rod 68 moves forward and backward relative to the gear and the gear 4, and the opening degree of the throttle valve 70 changes. Note that the lever 72 has a tendency to return to rotation in the direction of closing the throttle valve 70, that is, in the clockwise direction in FIG. 2, by a coil spring 76.

The levers 72 of the left and right forks 26 are connected by a link 78, as shown in FIG. Also, the left fork 2
One end of a wire 80 is locked to the lever 72 of No. 6, and the other end of the wire 80 is pulled when braking the front wheels in conjunction with a front brake lever (not shown).

Next, the operation of this embodiment will be explained. During normal driving without applying the front brake, the lever 72 is returned to its original state by the spring 76, and the flow resistance of the throttle valve 70 is large. If the front wheel 34 runs over an obstacle in this state, the fork 26 will be compressed. Then, the inner cylinder 40 enters into the outer cylinder 42, and the piston rod 68 enters into the cylinder 44. At this time, the buffer spring 38 is compressed. As the piston 48 moves, oil flows from the second oil chamber 52 to the first oil chamber 50, but at this time, the valve of the piston 48 through which the oil passes has very little resistance, so the oil passes through this valve and enters the throttle valve 70. There is almost no flow. When the piston rod 46 enters the cylinder 44, the oil in the cylinder 44 by the volume of the rod 46 flows through the base valve 54 to the third oil chamber 58 and the bottom of the outer cylinder 42. At this time, the base valve 54 through which the oil passes has a large resistance. After all, a damping force is obtained by the base valve 54 during this compression. Note that the flow of oil during this compression is shown by solid line arrows in FIG.

When the fork 26 is extended, the oil in the first oil chamber 50 flows into the second oil chamber 52 through the valve of the piston 48 that has a large resistance and the throttle valve 70 that also has a large resistance, and at this time, a large damping force is generated. is obtained. This extensional damping force is greater than the compression damping force. As the piston rod 46 withdraws from the cylinder 44, oil flows from the third oil chamber 58 to the second oil chamber 52 through the base valve 56, which has low resistance. The flow of oil during this elongation is shown in broken lines in FIG.

When the front brake is applied, the levers 72 of the left and right forks 26 rotate simultaneously, the control rod 68 moves to exit from the oil passage 66, and the opening degree of the throttle valve 70 increases.

Therefore, when the fork 26 is extended, the resistance of the oil flowing from the first oil chamber 50 to the second oil chamber 52 through the throttle valve 70 is reduced, and the extension damping force is reduced. Therefore, when the front wheels are braked, the front wheels 34 extend and follow even small depressions in the road surface.

When the front wheel is braked, a compressive force is always acting on the fork 26, but the fork 26 easily extends and becomes long, and compressive damping force is generated from that long state, so the fork 26 is in an extended state compared to when not braking. It has characteristics that make it easy to maintain. As a result, the front of the vehicle body is prevented from sinking.

In this embodiment, the extensional damping force is continuously adjusted by the throttle valve 70, but it goes without saying that various structures are possible depending on the structure of the damper. It may also be made to decrease stepwise and discontinuously.

In addition, in this embodiment, the present invention is applied to a telescopic type front fork in which the attenuator is built into the front fork 26, but it can be applied not only to the bottom link type, R's type, rocker arm type, etc., but also to various types of front wheels for automobiles. It is also applicable to suspension dampers.

As described above, the present invention is configured to reduce the extensional damping force in conjunction with front wheel braking, so that when the front wheels are braked, the front wheels can easily follow small depressions on the road surface and extend easily, while during compression operation, the front wheels are the same as when not braking. Since a damping force is generated, it has a characteristic that it is more likely to be maintained in an extended state when braking than when not braking.

As a result, the front of the vehicle body is prevented from sinking. In addition, since the compression damping force is the same as when no braking is applied, shocks from bumps on the road surface can be well absorbed, improving ride comfort and handling stability. Furthermore, since a sufficiently large extensional damping force is generated when the vehicle is not braking, the steering stability and riding comfort during normal driving will not be deteriorated.

[Brief explanation of the drawing]

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is a plan view of the upper portion of the front fork, and FIG. 3 is a sectional view of the front fork. 26...Front fork, 34...Front wheel, 36.
...Attenuator.

Claims (1)

[Claims] 1. A cylindrical hydraulic damper for front wheel suspension, which is capable of adjusting extensional damping force, and further comprising a damping force adjustment mechanism that reduces the extensional damping force in accordance with an increase in front wheel braking force.