JPH0115583Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an anti-dive mechanism for a front fork that prevents the front part of the vehicle body from sinking when the vehicle is braked.

For example, when braking is applied to a running two-wheeled vehicle, the center of gravity of the vehicle moves forward due to inertia, causing the front of the vehicle to sink, and this phenomenon impairs steering stability.

Therefore, a so-called anti-dive mechanism was installed in the front fork to prevent this phenomenon.
Various anti-dive mechanisms have been proposed so far.

For example, a piston case is fixed to the side of the bottom case to form an oil passage in the case, an oil hole that opens to the oil passage is bored in the bottom case, and a piston that opens and closes the oil hole is connected to the piston. The piston is slidably supported in the case, and the outer end of the piston is connected to a braking member, and when braking, the piston connected to the braking member slides to close the oil hole. An anti-dive mechanism is known that blocks the flow of hydraulic oil sealed in a hydraulic fluid.

By the way, in such an anti-dive mechanism, the piston is integrally molded, so once it is installed, the gap between the piston and the oil hole remains constant when the anti-dive mechanism is not in operation. Therefore, it is not possible to arbitrarily change the gap to adjust the responsiveness of the anti-dive mechanism to braking or the magnitude of the damping force generated based on the flow resistance of oil passing through the gap.

The present invention was developed to effectively eliminate such inconveniences, and its purpose is to improve the responsiveness of the piston to braking operations by arbitrarily changing the gap between the piston and the oil hole. To provide an anti-dive mechanism for a front fork that can appropriately adjust the magnitude of damping force of the front fork.

In order to achieve this purpose, the present invention has a piston that is slidably supported by a piston case fixed to the side of the bottom case and that opens and closes an oil hole that opens into an oil passage formed in the piston case. and a cylindrical valve member which is screwed into the main body so as to be freely retractable.

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

FIG. 1 is a partially cutaway side view of a front fork equipped with an anti-dive mechanism according to the present invention, and FIG. 2 is an enlarged cutaway side view of a piston portion of the anti-dive mechanism.

In the front fork 1 shown in FIG. 1, 2 is a bottom case with an open upper end, and a fork pipe 3 is inserted and fitted into the bottom case 2 from above so as to be vertically slidable. Further, as shown in the figure, a seat pipe 4 with an open upper end is installed in the inner bottom of the bottom case 2 with a bolt 5, and the tip piston portion 4a of the seat pipe 4 is in sliding contact with the inner periphery of the fork pipe 3. There is. Further, an oil hole 4b is bored in the lower end of the seat pipe 4, and two oil lock pieces 6 and 7 are fitted on the outer periphery of the oil hole 4b so as to be vertically slidable. There is. The upward movement of the upper piece 6 is restricted by a stopper ring 8, and both pieces 6 and 7
A spring 9 is compressed between them as shown.

On the other hand, the upper end of the fork pipe 3 is closed with a fork bolt 10, and a free valve 11 that slides on the outer periphery of the seat pipe 4 and an inner periphery of the free valve 11 are provided on the inner periphery of the lower part of the fork bolt 10. An oil lock collar 12 that fits around the outer periphery of the lock piece 6 is fitted. A coil spring 13 is stretched between the fork bolt 10 in the fork pipe 3 and the upper end surface of the seat pipe 4 as shown in the figure. 1 in Figure 1
4 is a rebound spring.

In this way, the inside of the front fork 1 is divided into seat pipe inner/outer chambers S ₁ , S ₂ and upper chamber S ₃ , and hydraulic oil is sealed in these chambers S ₁ , S ₂ , S ₃ . The upper part of chamber S ₃ is occupied by gas.

By the way, as shown in the figure, a part of the lower outer periphery of the bottom case 2 protrudes outward a little to form a thick walled part 2a, and the thick walled part 2a has the inner and outer chambers S ₁ and S ₂ of the sheet pipe. An oil passage 15 that communicates with each other is integrally formed, and an oil passage 16 that communicates with the oil passage 15 is passed through the bottom case 2.

An adjuster 17 is rotatably fitted and held in the oil passage 16, and an adjustment dial 18 is fixed to the outer end of the adjuster 17. Also this adjuster 1
7 has a bottomed cylindrical portion 17a, and a plurality of orifices 17b of different diameters that selectively open into the oil passage 15 are provided on the peripheral wall of the cylindrical portion 17a.

On the other hand, an anti-dive mechanism 20 according to the present invention is provided at another location in the lower part of the bottom case 2.

In the above anti-dive mechanism, 21 is the bolt 2
2... is a piston case fastened to the side of the bottom case 2, and inside the piston case 21 there is an oil passage 23 defined by the outer periphery of the bottom case 2.
is formed, and the oil passage 23 is connected to the bottom case 2.
The seat pipe is connected to the outer chamber through the oil hole 2b drilled in the
Connected to _S2 .

Also, a circular hole 21 is provided in the upper part of the piston case 21.
A is bored into the circular hole 21a, and a piston 24 is slidably inserted and fitted into the circular hole 21a as shown in the figure.
The piston 24 is always urged outward by a spring 25.

By the way, as shown in detail in FIG. 2, the piston 24 is composed of a piston main body 24a and a cylindrical valve member 24b that is screwed into the piston main body 24a so as to be able to move forward and backward. The end portion is bent outward to form a flange portion 24b-1. An elastic packing 27 is fitted and held in a ring-shaped recess 2c provided around the oil hole 2b provided in the bottom case 2. In the figure, the dust boot 21b is a drain hole, and 29 is a bolt that closes the drain hole 21b.

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

First, in the compression stroke, when the fork pipe 3 moves downward relative to the bottom case 2 and the seat pipe 4, the volume of the seat pipe outer chamber _S2 decreases, and part of the oil corresponding to this decrease is transferred to the seat pipe. outside room
_S2 flows into the seat pipe interior chamber _S1 through the oil hole 2b, oil passages 23 and 16, and oil hole 4b, and the remaining oil flows into the oil passage 15 and the orifice 17b provided in the adjuster 17... The oil flows into the seat pipe interior chamber _S1 through one of the orifices that opens to the oil passage 15, the oil passage 16, and the oil hole 4b.

During this compression stroke, when oil passes through each flow path, a required damping force is generated within the front fork 1 based on this flow resistance.

Next, in the extension process, if the fork pipe 3 moves upward within the bottom case 2, the inner space of the seat pipe
The oil in S ₁ flows into the seat pipe outer chamber S ₂ following a path opposite to that during the compression stroke, and in this case as well, a required damping force is generated in the front fork 1 as described above.

By the way, if braking is applied to the vehicle while the vehicle is running, the piston 24 is made to slide by some means linked to this braking, and the flange portion 24b-1 of the cylindrical valve member 24b of this is pressed against the elastic packing 27. The oil hole 2b is completely closed.

On the other hand, during braking, the center of gravity of the vehicle moves forward due to inertia, causing the front fork to move forward.
is about to be compressed, but since the oil hole 2b is blocked as described above, the oil in the seat pipe outer chamber _S2 is slightly compressed by the oil passage 15, the orifice opening to the oil passage 15, the oil passage 16, and the oil inside the seat pipe outer chamber S2. It flows into the seat pipe interior chamber _S1 through the hole 4b. At this time, orifice 17b
The opening area of the fork pipe 3 is very small, and the flow resistance of the oil flowing there is very high, so the downward movement of the fork pipe 3, that is, the sinking of the front part of the car body, is effectively prevented.
This is where the anti-dive mechanism comes into play.

In the above, since the piston 24 is constituted of the piston body 24a and the cylindrical valve member 24b which is screwed into the piston body 24a so as to be able to move forward and backward as described above, there is a gap ΔC between the piston 24 and the oil hole 2b.
can be arbitrarily adjusted by rotating the valve member 4b to move it forward or backward.

Since the gap ΔC can be adjusted in this way, the damping force generated in the front fork 1 based on the responsiveness of the anti-dive mechanism 20 to braking operations and the flow resistance of oil passing through the gap ΔC when braking is not applied. etc. can be adjusted arbitrarily.

As is clear from the above description, according to the present invention, the oil hole is slidably supported by the piston case fixed to the side of the bottom case of the front fork, and opens and closes the oil hole that opens into the oil passage formed in the piston case. Since the piston is composed of a piston main body and a cylindrical valve member that is screwed into the main body, the gap between the piston and the oil hole can be arbitrarily changed.
This allows the responsiveness of the anti-dive mechanism, the damping force of the front fork, etc. to be adjusted appropriately.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and Fig. 1 is a partially cutaway side view of a front fork equipped with an anti-dive mechanism according to the present invention, and Fig. 2 is an enlarged broken side view of the piston portion of the anti-dive mechanism. FIG. In the drawing, 1 is a front fork, 2 is a bottom case, 3 is a fork pipe, 20 is an anti-dive mechanism, 21 is a piston case, 23 is an oil passage, 24
24a is a piston, 24a is a piston body, and 24b is a cylindrical valve member.

Claims (1)

[Scope of utility model registration request] A piston case is fixed to the side of the bottom case of a front fork of a motorcycle, etc., in which a fork pipe is slidably inserted and fitted into the bottom case, and an oil passage is formed in the case. In the anti-dive mechanism for a front fork, the anti-dive mechanism for a front fork is provided with an oil hole opening into a passage, and a piston facing the oil hole and normally biased in an opening direction is slidably held in the piston case. An anti-dive mechanism for a front fork, characterized in that the piston is composed of a piston main body and a cylindrical valve member that is screwed into the main body so as to be movable forward and backward.