JPH0242908Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a front fork that continuously increases the generated damping force in proportion to the increase in compression stroke.

For front forks of motorcycles, etc.,
Compression damping force is kept as low as possible to maintain high ride comfort. For this reason, there was a problem in that the vehicle body sank forward during sudden braking, impairing steering stability.

The present invention was developed to solve the above problems, and its purpose is to continuously increase the damping force in proportion to the increase in the compression stroke, thereby improving the handling stability of motorcycles, etc. It's on offer fork.

In order to achieve such an object, the present invention provides a front fork in which an inner and an outer cylinder are slidably fitted together, and a base end of a tapered adjusting rod that is tapered at the upper end of the inner cylinder is swingable. At the same time, a base end of a tapered adjustment rod is swingably fixed to the upper end of the inner cylinder, and a valve case is connected and fixed to an upper end opening of a seat pipe rising from the lower end of the outer cylinder, Inside this valve case,
The present invention is characterized in that a relief valve is provided which opens at a hydraulic pressure of a predetermined value or higher during the compression stroke, and the adjustment rod is inserted through the relief valve so as to form a gap that exerts a damping effect on the outer periphery of the adjustment rod.

A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

The drawing is a longitudinal sectional side view of a front fork 1 according to the present invention, and as shown, an inner cylinder 3 is inserted and fitted into an outer cylinder 2 from above. Further, a seat pipe 4 is installed at the bottom of the outer cylinder 2 with a bolt 5, and its upper end piston portion 4a is in sliding contact with the inner periphery of the inner cylinder 3 as shown. In addition, seat pipe 4
Oil holes 4b... are bored in the side wall of.

On the other hand, the upper end of the inner cylinder 3 is closed with a fork bolt 6, and a bolt 7 extending downwardly of the fork bolt 6 is connected to the lower end via a joint, for example, a universal joint 8, which is connected with a certain degree of freedom. The upper end of a tapered adjusting rod 9 is fixed to the upper end.

By the way, a cylindrical valve case 10 is fixed to the upper end of the seat pipe 4, and an oil hole 10a is formed in the side wall of the valve case 10 in the vertical direction.
..., 10b..., 10c... are bored. In this valve case 10, the oil hole 10a is provided.
A relief valve 12 is fitted, which is urged downward by a spring 11 in order to close the adjustment rod 9, and the relief valve 12 is in sliding contact with the outer periphery of the adjustment rod 9 with a gap _ΔC provided therebetween. Also, valve case 1
0 includes a check valve 1 to close the oil hole 10c.
3 is urged upward by a spring 14 and fitted. Then, the valve case 10 inside the inner cylinder 3
A coil spring 15 is stretched between the fork bolt 6 and the fork bolt 6 as shown in the figure.

On the other hand, an oil seal 17 is provided on the inner periphery of the upper part of the outer cylinder 2.
The upper part of the oil seal 17 is covered with a dust seal 18.

Therefore, inside the front fork 1 are the chambers S ₁ , S ₂ ,
It is divided into chambers S ₃ and S ₄ , and hydraulic oil is sealed in each chamber S ₁ , S ₂ , S ₃ , and S ₄ , and the upper part of chamber S ₄ is occupied by air.

Next, the function of the front fork 1 will be explained.

During the compression stroke in which the inner cylinder 3 moves downward inside the outer cylinder 2, the oil in the chamber _S2 flows through the oil hole 4 provided in the seat pipe 4.
Part of this oil flows into the chamber S ₁ through the oil hole 10b provided in the valve case 10, and the remaining oil flows into the chamber S ₁ through the relief valve 12. The oil flows into the chamber S4 through the gap ΔC formed between the _oil and the adjusting rod 9, and as a result, _{the oil level in the chamber S4 rises} . During this compression stroke, a required damping force is generated within the front fork 1 based on the flow resistance when oil passes through each oil hole 4b..., 10b... and gap _ΔC , but the compression stroke increases. As the adjusting rod 9 moves downward together with the inner cylinder 3, the gap _ΔC gradually becomes smaller.As a result, the flow resistance of oil passing through the gap _ΔC increases, and therefore the generated attenuation decreases. Power increases continuously. In this way, since the damping force increases continuously in proportion to the increase in the compression stroke, the handling stability of a two-wheeled vehicle or the like is improved.

During this compression stroke, if an excessive shock is suddenly applied from the outside, the oil pressure inside the chamber _S1 will increase, and the pressure will push up the relief valve 12 against the elastic force of the spring 11. Since the pressure oil in the chamber _S1 is released into the chamber _S4 , external shocks are effectively absorbed and alleviated.

On the other hand, during the extension stroke in which the inner cylinder 3 moves upward within the outer cylinder 2, the oil in the chamber _S4 flows into the chamber _S1 through the oil holes 10b... and the gap _ΔC , and The oil passes through the oil holes 10c, uses its pressure to push open the check valve 13, flows into the chamber _S1 , and generates the required damping force during the extension stroke as described above.

As described above, the damping force increases continuously in proportion to the increase in the compression stroke, which effectively prevents the front part of the vehicle body of a motorcycle, etc., from sinking during sudden braking, and also helps to cope with excessive impact. It becomes possible,
Therefore, the compact configuration improves the handling stability of a two-wheeled vehicle or the like.

Also, the adjustment rod 9 is connected to the inner cylinder 3 via the universal joint 8.
Since the adjusting rod 9 is fixed to the inner upper end, the sliding contact between the adjustment rod 9 and the relief valve 12 is good even if an assembly error occurs between the two.

As is clear from the above explanation, according to the present invention,
In a front fork consisting of an inner and an outer cylinder that are slidably fitted together, a downwardly tapered adjustment rod is fixed to the upper end of the inner cylinder via a joint, and a relief valve is provided on the outer periphery of the adjustment rod. Because of the sliding contact, the damping force increases continuously in proportion to the increase in the compression stroke, and a compact front fork that can handle excessive impact is realized.
The steering stability of motorcycles, etc. can be improved.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional side view of the front fork according to the present invention. In addition, in the drawing, 1 is a front fork, 2 is an outer cylinder, 3 is an inner cylinder, 4 is a seat pipe, 8 is a universal joint, 9 is an adjustment rod, 10 is a valve case, 12
is a relief valve, S ₁ to S ₄ are chambers, and Δ _C is a gap.

Claims (1)

[Scope of utility model registration request] In a front fork, the inner and outer cylinders are slidably fitted together, a seat pipe is planted in the bottom of the outer cylinder, and a piston part at the upper end of the seat pipe slides into contact with the inner periphery of the inner cylinder. The base end of a tapered adjustment rod is fixed to the upper end so as to be able to swing freely, and a valve case is connected and fixed to the upper end opening of the seat pipe. A front fork characterized in that a relief valve that opens with hydraulic pressure is provided, and the adjustment rod is inserted through the relief valve so as to form a gap that exerts a damping effect on the outer periphery of the adjustment rod.