JPH0375781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an anti-nose dive type front fork used in motorcycles and the like.

When a motorcycle is braked while it is running, the rider's weight is added to the handlebars due to inertia, causing the fork pipe of the front fork to sink into the bottom case, impairing steering stability. For this reason, anti-nose dive type front forks are known that have a mechanism to prevent sinking, but conventionally the anti-nose dive mechanism is generally installed outside the bottom of the bottom case via an oil passage. The device has become complicated and large, and it has been extremely difficult to apply and improve it to existing front forks that do not have these mechanisms. Furthermore, if such a mechanism is provided below the coil spring interposed in the fork pipe, there is a tendency for the steering stability to be generally impaired, and there is also a problem in responsiveness.

This invention proposes an anti-nose dive type front fork for the purpose of solving the above-mentioned problem. The gist of this invention is to provide an oil passage through which hydraulic oil flows inward, and to close the oil passage by pushing a plunger using a rocker arm that is interlocked when the brakes of a motorcycle are applied. In addition, a select valve is installed in the oil passage between the inside of the hollow rod and the inside of the fork bolt, and the damping force on the compression side can be adjusted by multiple oil holes of different diameters drilled in the select valve. It is.

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

1 is a fork pipe, the lower part of which is slidably fitted into a bottom case (not shown). A hollow fork bolt 2 is fixedly installed in the upper end of the fork pipe 1, and the upper end of a hollow rod 3 is internally screwed into the lower end of the lower cylindrical body part 2a of the hollow fork bolt 2. There is. On the other hand, the tip of a sheet pipe (not shown) installed at the bottom of the bottom case is slidably fitted between the hollow rod 3 and the fork pipe 1 together with the coil spring 4 interposed above it. There is.

The hollow fork bolt 2 has a housing 5.
is fitted inside, and the cylindrical body part 2 of the fork bolt 2
An annular gap oil passage 6 is formed between the oil passage and the oil passage a. An adjusting case 7 is fixedly fitted into the lower part of the housing 5, and a cylindrical select valve 8 is rotatably fitted into the adjusting case 7, so that the lower end of the select valve 8 is directed toward the upper end of the hollow rod 3. I'm letting you do it. The select valve 8 is provided with a plurality of oil holes 8a of different diameters at predetermined positions in the circumferential direction.
Oil holes 7a and 5a are drilled at positions corresponding to the above, respectively, and the oil holes 5a communicate with the gap oil passage 6. Further, an oil inlet hole 5b is formed in the side wall of the housing 5 opposite to the upper part of the gap oil passage 6, so that the oil chamber in the housing 5 and the gap oil passage 6 are communicated with each other. Further, an oil outflow hole 5c is formed above the oil inflow hole 5b of the housing 5, and an oil passage 2 is provided which communicates the oil outflow hole 5c with the oil chamber upper part 1a in the fork pipe 1.
b is bored in the upper part of the fork bolt 2. A slide valve 9 that closes during the front fork compression process is provided below the oil passage 2b.

Reference numeral 10 designates an adjusting guide housing that closes the upper end of the housing 5, and a plunger 11 is provided with an upper portion of the plunger 11 projecting through the adjusting guide housing 10 and a lower portion fitted into the housing 5 so as to be vertically slidable. ing. The lower part of the plunger 11 has a spring seat shape that supports the upper end of a coil spring 12, and the coil spring 12 is interposed between the upper end of the adjusting case 7 and presses the plunger 11 upward at all times. Further, the outer periphery of the intermediate portion of the lower part of the plunger 11 is reduced in diameter to form an annular oil passage 11a that connects the oil outflow/inlet holes 5c and 5b of the housing 5.

A rocker arm 13 is rotatably supported on a support shaft 13a at the upper part of the adjuster guide housing 10, and has an inner wire 15 connected to the tip of a brake wire 14 that is towed in conjunction with the braking mechanism of the motorcycle. , the Rocker arm 1
3 is connected to the upper part via the shaft 16, and when the brake wire 14 is towed, the Rotsukar arm 13
is adapted to swing about a support shaft 13a as a fulcrum. Further, the rocker arm 13 is provided with a protrusion 13b near the support shaft 13a on its side surface, and a bolt 13c screwed onto the protrusion is connected to the plunger 11.
It is held against the top edge. In addition,
17 is a collar that supports the upper spring holder of the coil spring 4 in a predetermined position, 18 is a nut fitted into the lower end of the cylindrical body portion 2a of the fork bolt 2 to fix the select valve 8, and 19 is a nut made of steel. It is a moderation mechanism consisting of a ball and a coil spring. Further, the inside is filled with hydraulic oil, and the fork pipe 1 is used by attaching the upper part to the handlebar side of the vehicle body and the lower part of the bottom case to the axle side.

In the anti-nose dive type front fork having the above configuration, when the braking mechanism is not working on the vehicle body, the oil leak/inlet hole 5 in the housing 5 is
c and 5b are communicated through an annular oil passage 11a on the outer peripheral side of the plunger 11. Therefore, during the compression process of the front fork, a part of the hydraulic oil in the hollow rod 3 flows into the select valve 8, and the oil holes 8a,
Oil hole 7a of adjusting case 7, oil hole 5a of housing 5, gap oil passage 6 formed between housing 5 and cylindrical part 2a of fork bolt 2, oil inlet hole 5b, annular oil passage 11a , the oil passes sequentially through the oil outflow hole 5c, passes through the oil path 2b of the fork bolt 2, pushes open the slide valve 9 downward, and flows out into the upper part 1a of the oil chamber in the fork pipe 1. Also, when the vehicle body is braked, the inner wire 1 is connected to the brake wire 14 which is pulled in conjunction with the braking mechanism
5. The rocker arm 13 swings about the support shaft 13a via the shaft 16, and the lower end of the bolt 13c screwed onto the rocker arm 13 comes into contact with the upper end of the plunger 11 and presses it downward. Make it descend. Therefore, the reduced diameter part of the intermediate outer circumference of the plunger 11 is the housing 5.
The large diameter part of the plunger 11 blocks the annular oil passage 11a and the oil outflow hole 5c in the upper part of the housing 5, and in order to prevent the flow of hydraulic oil, the hollow rod 3 and its The internal pressure of the lower sheet pipe increases, suppressing sinking. In addition, to adjust the damping force on the compression side, rotate the select valve 8 and adjust the oil hole 7 of the adjustment case 7 in advance.
This is done by aligning the oil hole 8a having a predetermined diameter with point a.

According to the present invention, as described above, since the anti-nose dive mechanism is provided above the coil spring stretched above the seat pipe, responsiveness is excellent and maneuverability is further improved. In addition, since the above mechanism is built into the fork bolt at the upper end of the fork pipe, an existing front fork can be improved to the one of this invention by simply replacing the fork bolt, offering excellent application, compatibility, and economy. ing. Furthermore,
This has great effects, such as making it possible to adjust the damping force on the compression side.

[Brief explanation of drawings]

FIG. 1 is an enlarged vertical cross-sectional view of a main part showing an embodiment of the present invention. 1...Fork pipe, 2...Fork bolt, 3...Hollow rod, 4, 12...Coil spring, 5...Housing, 6...Gap oil path, 7...
Adjustment case, 8...Select valve, 9...
... Slide valve, 10 ... Adjustment guide housing, 11 ... Plunger, 13 ... Rotsuker arm, 14 ... Brake wire.

Claims (1)

[Claims] 1. A fork pipe with a hollow rod implanted in the fork bolt at the upper end is slidably fitted into the bottom case, and a sheet pipe implanted in the bottom of the bottom case is slid to the outside of the hollow rod. In the front fork brought into contact, a hollow fork bolt is integrally formed with a cylindrical body portion communicating with the hollow rod, and an oil passage with a check valve communicating with the fork pipe is formed in the upper part; Fitted within the cylindrical body to form a gap oil passage communicating with the hollow rod, an oil inlet hole is provided in the side wall opposite to the gap oil passage, and an oil inlet hole is provided above the oil inlet hole, which communicates with the oil passage of the fork bolt. an adjustment guide housing that closes the upper end of the housing, an upper portion of the housing that extends upwardly through the adjustment guide housing, and a lower portion of the housing that is slidably inserted into the housing. A plunger is provided, and the outer periphery of the lower intermediate part is reduced in diameter to form an annular oil passage connecting the oil outflow and inlet holes of the housing. An anti-nose which is supported and interlocked via a wire or the like when the brake of a motorcycle is applied, swings about the support shaft as a fulcrum, and pushes the upper end of the plunger to close the oil inflow hole of the housing. Dive type front fork. 2. A cylindrical select valve is rotatably fitted into the lower part of the housing so that the lower end of the select valve faces the upper end of the hollow rod, and a plurality of oil holes of different diameters are provided at predetermined positions in the circumferential direction of the select valve. In addition, a compression-side damping force variable mechanism is provided in the housing by drilling an oil hole in the housing so that the oil chamber in the select valve and the gap oil passage communicate with each other. Anti-nose dive type front fork.