JPS58633Y2 - Front fork for motorcycles - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a front fork for a two-wheeled vehicle with increased cylinder strength.

At the upper end of the cylinder of the front fork for the motorcycle,
A snap ring is attached to the stopper provided at the lower end of the inner tube to hold the stopper against which the piston collides in a predetermined position.

However, in order to do this, it is necessary to form a groove for attaching the snap ring, so the thickness of the cylinder becomes thinner by the amount of the groove, and the strength of that part decreases.

In addition, an orifice is formed at the lower end to supply oil to the chamber below the piston body when the front fork is extended, but since the piston speed is quite high in front forks for motorcycles, the opening area of the orifice is relatively small. It has to be made larger, which inevitably weakens the strength of the lower end of the cylinder.

Moreover, a hydraulic lock mechanism is provided at the upper end of the cylinder to cushion the impact, but if the upper end is not strong enough,
There was a problem that the pressure at the time of the hydraulic lock could not be withstood.

Therefore, conventionally, based on maintaining the strength of the lower end of the cylinder,
The wall thickness of the entire cylinder was determined.

As a result, the wall thickness of the entire cylinder became considerably thicker, which not only increased the weight but also had disadvantages in terms of economy.

In addition, increasing the wall thickness of the cylinder means that the pressure chamber formed between the cylinder and the inner tube may not have enough volume, or the front fork may have to have a large diameter in order to maintain that volume. There were some drawbacks as well.

The object of this invention is to provide a front fork for a two-wheeled vehicle that eliminates the above-mentioned conventional drawbacks by increasing the thickness of the upper and lower ends of the cylinder.

This will be explained below with respect to each of the illustrated embodiments.

In the first embodiment shown in FIG. 1, 1 is an outer tube connected to the wheel side.

Reference numeral 2 denotes an inner tube connected to the vehicle body, which has a piston body 3 equipped with a damping force generating mechanism at its lower end, and is slidably inserted into the outer tube 1.

Reference numeral 4 denotes a cylinder whose lower end is fixed to the bottom of the outer tube 1 with a bolt 5, and an auxiliary piston 6 provided at the upper end faces into the inner tube 2, and the auxiliary piston 6 and the piston body 3 are connected to each other. The relationship is such that a pressure chamber 7 is formed between them.

The upper end 4a of the cylinder 4 has a midsection 4b.
The lower end portion 4c is made thicker in the inner diameter direction, and an orifice 8 is formed in the lower end portion 4c.

As mentioned above, the reason why the upper end portion 4a is made thicker in the outer diameter direction is because
For example, if it is made thicker in the inner diameter direction, the upper end 4a
This is to avoid the fact that the inner diameter of the cylinder becomes smaller in this area, which causes flow resistance to the oil in that area.

Further, the reason why the lower end portion 4c is made thicker in the inner diameter direction is to maintain the sliding surface between the piston 3 and the cylinder 4, and to maintain a sufficient sliding stroke of the piston body 3.

Reference numeral 9 denotes an upper stopper that is slidably fitted on the upper end 4a, and a spring 10 is interposed between this stopper 9 and the auxiliary piston 6, and a snap ring 11 that is firmly attached to the lower side of the upper end 43 is normally attached. They are in a close relationship.

A lower stopper 12 is slidably fitted to the lower end 4c, and a spring 13 is interposed between the stopper 12 and the bottom of the outer tube 1, and a snap is usually attached slightly below the orifice 8. It is in pressure contact with the ring 14.

Reference numeral 15 denotes a ring-shaped spacer that is slidably installed inside the inner tube 2, and is arranged so that it can come into contact with the lower end of the upper stopper 9.

However, when the front fork expands, the pressure chamber T
The oil inside flows into the chamber 16 via the damping force generating mechanism of the piston body 3 and generates a predetermined damping force.

The oil in the oil chamber 17 then flows into the chamber 16 through the cylinder 4 and the orifice 8.

When the front fork further extends, spacer 1
5 comes into contact with the lower end of the upper stopper 9, and the pressure chamber 7 enters the oil chamber lock state, and the oil in the pressure chamber 7 is discharged from the gap between the abutting portions and the impact is alleviated. 3 so as not to hit the upper end portion 4a.

Therefore, the spacer 15 has the upper end 4a of the piston body 3.
It goes without saying that the relationship length needs to be long enough to avoid hitting.

Next, the second and third embodiments shown in FIGS. 2 and 3 will be explained in order. In these second and third embodiments, the structure of the lower end of the cylinder is the same as that of the first embodiment, so the explanation will be omitted. Common elements will be omitted and explained using the same reference numerals.

In the second embodiment, when the lower end of the upper stopper 18 is in contact with the snap ring 11,
Along with extending it downward by the shock absorption stroke,
The spacer 15 in the first embodiment is omitted.

The other configurations are the same as in the first embodiment.

However, when the front fork reaches its maximum extension,
The upper stopper 18 directly abuts the piston body 3, and prevents the piston body 3 from abutting the upper end portion 4a, similar to the first embodiment.

The third embodiment shown in FIG. 3 has an upper end portion 4a of the cylinder 4.
Between the mid-abdomen 4b and the mid-abdomen 4b, there is an inclined portion 4d which gradually expands upward from the mid-abdomen 4b, and the wall thickness thereof gradually increases upward.

A cylindrical member 19 is fixed to the piston body 3 side with a ring 20.

This cylindrical member 19 has a protrusion 19a on its inner surface.

When the front fork is fully extended, the protruding portion 19a gradually reduces the distance between the protruding portion 19a and the inclined portion 4d, hydraulically locking the pressure chamber 7, and locking the piston body 3.
is prevented from hitting the upper end portion 4a and the inclined portion 4d.

As is clear from the above explanation, according to the front fork of this invention, the wall thickness at the top and bottom ends of the cylinder can be made sufficiently thick, so even if a groove for attaching the snap ring is formed, the strength of that part is maintained. can.

Furthermore, even if an orifice is formed at the lower end of the cylinder, its strength is of course maintained.

Moreover, since the wall thickness of only the upper and lower ends of the cylinder is increased, there is no need to increase the wall thickness of the entire cylinder.

Since it is not necessary to increase the wall thickness of the entire cylinder, the volume of the pressure chamber formed between the cylinder and the inner tube can be made sufficiently large without increasing the outer diameter of the front fork.

Furthermore, since the upper end of the cylinder is made thicker in the direction of its outer diameter, there is no flow resistance to the oil passing through the cylinder.

Furthermore, even if the pressure in the pressure chamber of the hydraulic lock mechanism formed at the upper end increases, the strength of the cylinder portion corresponding to the pressure chamber is maintained sufficiently.

Furthermore, since the lower end of the cylinder is made thicker in the inner diameter direction, a sufficient sliding stroke between the cylinder and the piston body can be maintained.

[Brief explanation of drawings]

FIG. 1 is a partially sectional view of the first embodiment, FIG. 2 is a sectional view of the main part of the second embodiment, and FIG. 3 is a sectional view of the main part of the third embodiment. 1...Outer tube, 2...Curved inner tube, 3...Piston body, 4...Cylinder, 4a...Upper end, 4b...・・・
- Middle abdomen, 4c... lower end of curve, 6... auxiliary piston.

Claims (1)

[Scope of utility model registration request] An inner tube having a piston body equipped with a damping force generating mechanism at the lower end is slidably inserted into the outer tube, and a reinforcing piston is installed at the upper end of the cylinder whose lower end is fixed to the bottom of the outer tube. In a front fork for a two-wheeled vehicle in which this auxiliary piston faces inside the inner tube, the thickness of the upper end of the cylinder is made thicker in the outer diameter direction, and when the front fork is extended, oil is applied to a position corresponding to the thicker part. While forming a locking mechanism, the wall thickness of the lower end of the cylinder is made thicker in the inner diameter direction, and an orifice is formed in the thicker part.
A front fork for two-wheeled vehicles with a snap ring firmly attached to the thick part of this part to hold the lower stopper.