JPH0427073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shock absorber for a vehicle that changes damping force as the stroke of the shock absorber changes.

(Prior Art) Conventionally, some vehicles such as motorcycles are provided with a shock absorber to damp vertical vibrations of the vehicle body caused by unevenness of the road surface.

(Problem to be solved by the invention) However, since this shock absorber is configured to always generate a constant damping force regardless of stroke changes, the damping force on the compression side is lowered with emphasis on riding comfort. If this is set, it will cause bottoming out when two people ride, etc., resulting in poor running performance.On the other hand, if the damping force on the compression side is set to be high to prevent bottoming out, the ride comfort will deteriorate. There is a problem.

As a prior art to solve this problem,
A buffer device disclosed in No. 29467 is known.
This shock absorber has a link mechanism interposed between the swing arm and the shock absorber, and the amount of rocking displacement of the swing arm is increased depending on the position and transmitted to the shock absorber. However, such a structure in which transmission is performed through links may cause looseness, an increase in the number of parts, and an increase in weight.

The present invention was made in view of the above problems, and its purpose is to be able to change the damping force as the stroke changes without adopting a complicated link structure, and to set the damping force with emphasis on riding comfort. To provide a buffer that does not cause bottoming out, etc.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an upper part of a hydraulic shock absorber that generates a damping force by passing the hydraulic oil in the cylinder through an orifice formed in the cylinder. In a vehicle shock absorber which is attached to the body frame of the vehicle and the lower part of the hydraulic shock absorber is attached to a swing arm extending swingably from the body frame or a cushion arm interlocking with the swing arm, one end is located inside the cylinder. is inserted, and a push rod with the other end protruding outside the cylinder is slidably provided, and a damping force adjustment means is provided below the orifice in the cylinder to change the damping force of the shock absorber by vertical movement of the push rod, and the swing The present invention is characterized in that a cam surface is formed on the arm or the cushion arm to move the push rod up and down by the swinging of the swing arm.

(Function) The damping force of the shock absorber can be changed as the stroke changes, and even if the damping force on the compression side is set with emphasis on riding comfort, it is possible to prevent bottoming out while driving.
As a result, a comfortable ride can be ensured and driving performance can be improved.

(Embodiment) A preferred embodiment of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a side view of the shock absorber according to the present invention, and FIG.
The figure shows a partially enlarged view of FIG. 1, in which 1 is a body frame of a motorcycle, and the base end of a swing arm 3 extending toward the rear of the vehicle body is connected to a bracket 2 formed on the frame 1 via a shaft portion 4. The swing arm 3 is mounted so as to be swingable in the vertical direction, and the rear wheel 5 is pivotally supported at the tip of the swing arm 3. A cushion arm 6 is attached to a portion of the vehicle body frame 1 below the swing arm 3 via a shaft portion 7 so as to be swingable in the vertical direction, and a shaft portion 8 provided at an intermediate portion of the cushion arm 6 is attached to the Bracket 9 formed below swing arm 3
Rotatably supported on the shaft.

When the swing arm 3 swings in the vertical direction, the swing arm 3 also swings in the vertical direction in conjunction with this.

Reference numeral 10 denotes a shock absorber, the upper end of which is provided at the upper end of an upper bracket 11 which also serves as a spring receiver is pivotally supported on a bracket 12 formed on the vehicle body frame 1, and the lower end is connected to bolts 14, 14 via a support member 13.
Attach it to the tip of the cushion arm 6 at .

The details of the shock absorber 10 are as shown in FIG. 3, and hydraulic oil is sealed in the cylinder 20 of the shock absorber 10.
The cylinder 20 consists of an outer periphery 15 and an inner cylinder 16 fixedly installed within the outer periphery 15, and an intermediate chamber S4 is formed between the outer cylinder 15 and the inner cylinder 16. Further, a bottom member 17 is fixed to the lower part of the outer cylinder 15, and the substrate 13a of the support member 13 described above is fitted to the outer periphery of the cylindrical portion 17a provided at the center of the bottom member 17.
The legs 13b, 13b hanging down from both ends of the cushion arm 6 are connected to the bolts 14, 14 as described above.
Install it. Further, a spring receiver 21 is provided on the outer periphery of the outer periphery 15 at a substantially intermediate portion, and a coil spring 22 is stretched between the spring receiver 21 and the upper bracket 11.
A partition wall 18 is provided at the lower end of the inner cylinder 16, and a piston 19 is provided in the inner cylinder 16 to form a chamber S in the cylinder 20.
1, S2, and S3, and the partition wall 18 has an oil passage 33.
... is provided to communicate between the intermediate chamber S4 and the chamber S1. The upper end of the rod 19a of the piston 19 is fixed to the upper bracket 11, and the cylinder 20 can swing freely relative to the piston 19. When the swing arm 3 swings up and down, the cylinder 20
(Directly, the inner cylinder 16) slides vertically relative to the piston 19.

A pin 13 is screwed into the center of the partition wall 18, and the pin 2 passes through the cylindrical portion 17a of the bottom member 17.
A push rod 24 is provided between the shaft portion 23a of No. 3 and the cylindrical portion 17a so as to be slidable in the vertical direction along the shaft portion 23a. On the other hand, the partition wall 18 has a plurality of orifices 24a.
..., 24b... (the outer orifice is
a..., the inner orifice is 24b...), a check valve 25 is provided on the upper surface of the partition wall 18, and a disc spring 36 is installed between the check valve 25 and the head 23b of the pin 23.
is provided, and the check valve 25 is always biased toward the partition wall 18 by the disc spring 36. At this time, the upper openings of the outer orifices 24a are closed by the check valves 25, but the upper openings of the inner orifices 24b are always in communication with S2 through the holes 25a. Further, a check valve 26 is provided on the lower surface of the partition wall 18 to close the lower opening of the inner orifice 24b, and the check valve 26 is always connected to the partition wall 18 by a coil spring 28 stretched between it and a spring support 27 provided at the upper part of the push rod 24. direction.

By the way, the push rod 24 protrudes from the bottom member 17 by a predetermined length, and as shown in FIG. are in contact with each other. When the cushion arm 6 swings upward, the tip of the push rod 24 slides along the cam surface 30, thereby causing the push rod 24 to slide upward (in the direction A). Along with this, the spring receiver 27 also moves upward, compressing the coil spring 28, and increasing the force urging the check valve.

In addition, 31 in the drawing indicates the outer cylinder 15 and the piston rod 1.
A seal member 32 is a seal member provided between the inner cylinder 16 and the piston 19.

Next, the operation of the present invention will be described.

First, when the rear wheel 5 moves upward due to unevenness on the road surface while driving and the swing arm 3 swings upward, the cushion arm 6 also swings upward in conjunction with this.
As a result, the inner cylinder 16 slides upward with respect to the piston 10, and the hydraulic oil in the chamber S2 flows from the hole 25a into the orifice 24b, pushes down the check valve 26, flows into the chamber S3, and further flows into the oil passage. 33 into the intermediate chamber S4. At this time, as the hydraulic oil flows through the orifice 24b and as the check valve 26 is pushed down, a damping force is generated in the compression stroke. On the other hand, at this time, the tip of the push rod 24 slides along the cam surface 30, so the push rod 24 slides upward (direction A), and as mentioned above, the spring receiver 27 also moves upward, and the coil spring 28
is compressed and the force that biases the check valve 26 is strengthened. That is, in the compression stroke, as the inner cylinder 16 moves upward, the damping force increases.

Since the present invention is configured as described above, even if the damping force is set to be a little weak with emphasis on ride comfort while driving, the damping force will increase as the cylinder moves upward during the compression stroke, and the damping force will increase while driving. It is possible to prevent the inside of the vehicle from bottoming out, etc., and it is possible to improve running performance while ensuring a comfortable ride.

In this embodiment, a cam surface is provided on the cushion arm 6 that is linked to the swing arm 3, and the push rod 24 is brought into contact with the cam surface.
This may be accomplished by providing a cam surface directly on the swing arm 3 and having the tip of the push rod 24 abut against this surface, thereby reducing the number of parts.

(Effects of the Invention) As described above, according to the present invention, the damping force of the shock absorber can be changed as the stroke changes without using a complicated link mechanism, and the damping force can be set with emphasis on ride comfort. It is possible to prevent bottoming out while driving, thereby ensuring a comfortable ride and improving driving performance.

[Brief explanation of drawings]

FIG. 1 is a side view of a shock absorber according to the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is a front sectional view of the shock absorber. In addition, in the drawing, 1 is a vehicle body frame, 3 is a swing arm, 6 is a cushion arm, 10 is a shock absorber, and 2
0 is the cylinder, 24 is the push rod, 24a,
24b is an orifice, 26 is a check valve, 27 is a spring receiver, 28 is a coil spring, and 30 is a cam surface.

Claims (1)

[Scope of Claims] 1. The upper part of a hydraulic shock absorber is configured to generate a damping force by passing the hydraulic oil in the cylinder through an orifice formed in the cylinder, and the upper part of the hydraulic shock absorber is attached to the body frame of a vehicle. In a vehicle shock absorber, the lower part of which is attached to a swing arm that swingably extends from the vehicle body frame or a cushion arm that interlocks with the swing arm, one end is inserted into the cylinder and the other end projects outside the cylinder. a damping force adjusting means for changing the damping force of the shock absorber by vertical movement of the push rod is provided in the vicinity of the orifice in the cylinder; 1. A shock absorbing device for a vehicle, characterized in that a cam surface is formed to move the push rod up and down by movement.