JPH0362933B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an anti-nose system for front forks, which is designed to increase spring characteristics during braking compared to normal driving, in springs installed in front forks used in motorcycles, etc. Regarding dive equipment.

When a motorcycle is braked while it is running, the rider's weight is added to the handlebars due to inertia, causing the inner cylinder of the front fork to sink into the outer cylinder, impairing steering stability and reducing cushioning performance. For this reason, various front forks have been developed that are equipped with a sinking prevention mechanism, that is, an anti-nose dive mechanism. On the other hand, a spring is tensioned inside the front fork, and the stroke amount of the front fork generally reaches its maximum when the brakes are fully applied. The characteristics were higher than required for normal driving, and ride comfort was impaired.

In view of the above points, the present invention proposes an anti-nose dive device for a front fork, the purpose of which is to increase the spring characteristics of the spring during braking compared to during normal driving. In detail, we focused on the anti-nose dive mechanism, which is a structure that blocks the compression side hydraulic oil flow path that connects the inner and outer oil chambers of the seat pipe during braking, and by blocking the flow path, the outer oil chamber of the seat pipe Taking advantage of the increase in internal pressure of It moves upward due to the internal pressure due to the intrusion volume, compressing the spring stretched between the upper part of the inner cylinder and the free piston, increasing the spring characteristics and preventing the inner cylinder from intruding into the outer cylinder. The gist is that the structure has been designed to work in this manner.

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

FIG. 1 shows an anti-nose dive type front fork of the type that blocks a bypass flow path. Reference numeral 1 designates an inner cylinder, the upper part of which is attached to the handlebar of a motorcycle via a bracket or the like. The lower part of the inner cylinder 1 is slidably fitted onto the outer cylinder 2, and the upper end of a sheet pipe 3 implanted from the bottom of the outer cylinder 2 faces into the inner cylinder 1. A free piston 4 is slidably fitted into an annular gap formed between the seat pipe 3 and the inner cylinder 1, and the free piston 4 is fitted at the upper end of the outer periphery of the seat pipe 3 and below it. Stoppers 5 and 6 are fixedly installed to restrict the downward movement. Further, a spring 8 is stretched between the bolt 7 that closes the inner upper end of the inner cylinder 1 and the free piston 4. A check valve 9 is provided at the lower end of the inner cylinder 1, and oil holes 10 and 11 are provided at the upper and lower parts of the seat pipe 3, respectively. An oil lock piece 12 is fitted onto the base end of the seat pipe 3, and an O-ring 13 is attached to the fitting surface of the oil lock piece 12 with the outer cylinder 2. In addition, 14 is an oil hole drilled in the oil lock piece 12, 15 is an annular check valve pressed by a spring 16 at the upper end of the oil lock piece 12,
17 is the axle mounting hole, 18 is the oil seal, 19
indicates a guide button. Further, a bypass flow path 20 is bored in the side wall of the lower end of the outer cylinder 2, and connects the inner and outer oil chambers of the sheet pipe 3.
One end of a piston valve 21 provided at 0 protrudes outside from the outer cylinder 2. The piston valve 2
One end of the caliper bracket 22 contacts the tip of a caliper bracket 22 whose base end is pivoted to the upper part of the outer wall of the outer cylinder 2;
The caliper bracket 22 is rotated in the direction of the arrow in conjunction with the braking mechanism and is pushed to block the bypass passage 20. Note that 23 is a return spring.

In the front fork constructed as described above, when braking is applied while the vehicle is running, the caliper bracket 22 rotates in the direction of the arrow in the figure, pushes the piston valve 21, and blocks the bypass passage 20 as shown. Therefore, since the hydraulic oil cannot flow from the outer oil chamber A of the seat pipe 3 to the inner oil chamber C of the seat pipe 3, as shown on the right side of the center line in the figure, after the bypass flow path 20 is shut off, the inner cylinder 1 Oil room A
The internal pressure of the oil chamber A rises due to the volume of oil that enters into the oil chamber A, which opens the check valve 9 and flows into the oil chamber B, causing the free piston 4 to move upward and compress the spring 8. Therefore, the spring 8 is affected by the sinking displacement of the inner cylinder 1 and the displacement of the free piston 4 due to braking, thereby increasing the spring characteristics of the entire front fork. Therefore, the load required for the entry of the inner cylinder 1 becomes large, the sinking of the handle is restricted, and stable maneuverability can be maintained. Also, during normal driving, the caliper bracket 22 is biased by the return spring 23 in the direction opposite to the arrow in the figure, so the piston valve 21 is pushed outward of the outer cylinder 2 by the hydraulic oil and moves to the outside of the outer cylinder 2, causing the bypass Channel 20 is opened. Therefore, during the compression process, the check valve 9 rises, and the hydraulic oil in the lower part of the inner cylinder 1 passes through the radial groove formed on the upper surface of the valve 9 and moves to the oil chamber B in the upper part. The hydraulic oil A flows into the oil chamber C through the bypass passage 20 and the oil holes 14 and 11 in order, and generates a relatively small damping force. Also, during the extension process, as shown on the left side of the center line in the figure, since the check valve 9 closes, the hydraulic oil in the oil chamber B above the valve 9 squirts out into the seat pipe 3 from the oil hole 10, causing a large The hydraulic oil in the oil chamber C that generates a damping force passes through the oil hole 11, raises the bypass passage 20 and the check valve 15, and passes through the oil hole 11 into the oil chamber A.
leaks to. Note that the piston valve 21 is
Although it is operated by a caliper bracket 22 that is linked to a braking mechanism, it may also be operated hydraulically.

Figure 2 shows an anti-nose dive type front fork that directly blocks the oil hole for generating damping force during the compression process, 24 is an inner cylinder, 25 is an outer cylinder, 26 is a seat pipe, and 27 is a free piston. , 28 are springs, 29 and 30 are stoppers, 31 and 32 are oil holes, and 33 is a check valve, which function in the same manner as shown in FIG. A valve body 34 is slidably fitted into the lower portion of the seat pipe 26, and extends parallel to the axis of the seat pipe 26.
4 has an oil hole 35 drilled therein. The rod 36 that supports the valve body 34 is pulled out to the space inside the bottom metal at the bottom of the outer cylinder 25, and is pivoted to one end of a connecting fitting 37 that is pivoted to the bottom metal.
A brake wire 38 is pivotally attached to the other end of the brake wire 7 . Therefore, during braking, the brake wire 38 is pulled in the direction of the arrow in the figure, the connecting fitting 37 swings, the rod 36 moves in the direction of the arrow, and the rod 36 is attached to the peripheral wall of the valve body 34 fixed to its upper end. to close the oil hole 32. However, as in Figure 1, seat pipe 2
Since the hydraulic oil cannot flow from the outer oil chamber D of No. 6 to the inner oil chamber E of the seat pipe 26, the internal pressure of the oil chamber D increases, passes through the check valve 33, and then the free piston 27, blocking the oil hole 32. The volume of oil that enters the oil chamber D of the inner cylinder 1 moves upward and compresses the spring 28, increasing the spring characteristics of the entire front fork. This provides a sufficient anti-nose dive effect. In addition, the above rod 36
and the brake wire 38 may be connected by a cam type.

FIG. 3 is a diagram showing the spring characteristics of the front fork according to the present invention, where OBA is the line of the spring characteristics during normal running. Now, when the brake is applied at point B, the compression side flow path is blocked and the free piston moves in the opposite direction to the inner cylinder, which is equivalent to an apparent increase in the cushion stroke.
The load value at point A'' will occur at point A' in the actual cushion stroke.

According to this invention, as described above, the spring characteristics of the spring tensioned in the front fork are made to rise during braking compared to when driving normally, so the spring characteristics only need to be the values required during normal driving; The ride comfort is improved compared to the previous one. In addition, the anti-nose dive effect is fully exhibited, and it has excellent buffering performance and maneuverability, making it extremely useful.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view showing one embodiment of the present invention, Fig. 2 is a longitudinal sectional front view showing another embodiment of the invention, and Fig. 3 is a spring characteristic diagram showing the relationship between load and displacement. It is. 1,24...Inner cylinder, 2,25...Outer cylinder, 3,2
6... Seat pipe, 4, 27... Free piston, 5, 6, 29, 30... Stopper, 10,
11, 31, 32... Oil hole, 12... Oil lock piece, 20... Bypass passage, 21... Piston valve, 22... Caliper bracket, 2
3... Return spring, 34... Valve body, 36
...Rod, 37...Connection fittings, 38...Brake wire.

Claims (1)

[Claims] 1 The outer cylinder and the inner cylinder are slidably fitted, the tip of the sheet pipe planted from the bottom of the outer cylinder faces the inside of the inner cylinder, and the compression side of the sheet pipe connecting the inner and outer oil chambers is In an anti-nose dive front fork configured to block a hydraulic oil flow path during braking, a free piston is slidably fitted into an annular gap formed between the seat pipe and the inner cylinder. , a stopper that is fixedly installed at the upper end of the outer circumference of the seat pipe and below it to restrict the upward and downward movement of the free piston, and a stopper that is stretched between the upper part of the inner cylinder and the free piston and that moves upward during braking. A front fork anti-nose dive device comprising a spring compressed by a piston.