JPH0446232A - Front fork - Google Patents

Abstract

PURPOSE:To surely supply working oil to the sliding part between an outer pipe and an inner pipe and improve the workability of a front fork by positioning a slide bush and a lubricating hole below the liquid level of working oil. CONSTITUTION:An annular gap, i. g., an oil chamber 7 is formed between a slide bush 5 fitted on the outer periphery of the upper edge part of an inner pipe 2 and a guide bush 6 fitted on the inner periphery at the lower edge part of an outer pipe 2. The oil chamber 7 communicates to the working oil inside the inner pipe 2 through a lubricating hole 25. Since a lubricating hole 25 is formed so as to be positioned below a raised oil level 14a even in the case where a front fork most contracts, the exhaustion of the supply of the working oil into the oil chamber 7 is prevented even if the inner pipe 2 is set at any position, and the oil chamber 7 is always filled with working oil, and the slide contact surface between the slide bush 5 and the outer pipe 1 and the slide contact surface between the guide bush 6 and the inner pipe 2 can be sufficiently lubricated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a front fork that supports a front wheel of a two-wheeled vehicle, and more particularly to an inverted front fork that is disposed with an outer pipe at the top and an inner pipe at the bottom.

■This kind of inverted front fork is shown in Japanese Patent Publication No. 63-151593, but this front fork has an inner pipe that can be slid freely from below inside an outer pipe held on the vehicle body side. A damper cylinder is inserted coaxially into the inner pipe, the piston rod of the piston housed in the damper cylinder is connected to the outer pipe, and a rod guide is installed to freely slide in the middle of the piston rod. The rod guide is fixed inside the inner pipe, and a suspension spring is interposed between the rod guide and the outer pipe.

An inverted type front fork has various advantages over an upright type front fork, which has an outer pipe located at the bottom and an inner pipe located at the top. The sliding portion of the outer pipe and inner pipe where this occurs is located above the entire front fork.

Therefore, the present invention makes it possible to reliably supply hydraulic oil to the sliding parts of the outer vibe and inner pipe of an inverted front fork, thereby sufficiently lubricating these parts, and This is intended to improve the operability of the fork.

And for this reason, in the present invention, in an inverted front fork consisting of an outer vibe and an inner pipe slidably inserted into the outer vibe, the outer vibe is arranged with the outer vibe upward and the inner pipe downward. An oil chamber is formed between the guide bushing that is fitted to the lower end of the inner pipe and slides into contact with the inner pipe, and the slide bushing that is fitted to the upper end of the inner pipe and slides into contact with the outer vibe. A lubrication hole communicating with the fork is formed in the wall of the inner pipe, and the slide bush and the lubrication hole are positioned below the level of the hydraulic oil when the flon I/fork is contracted.

During the contraction stroke of the front fork, the oil chamber becomes negative pressure, and the internal hydraulic oil is sucked into the oil chamber through the lubrication hole, but the lubrication hole is located below the level of the hydraulic oil even when the front fork is most retracted. Therefore, there is no interruption in the supply of hydraulic oil to the oil chamber.

During the extension stroke of the front fork, the oil chamber becomes positive pressure,
Excess hydraulic oil is discharged through the lubrication hole, so that the oil chamber is always filled with hydraulic oil. This hydraulic oil sufficiently lubricates the slide bushing at the top of the oil chamber and the guide bushing at the bottom of the oil chamber. Since the upper slide bush is also located below the liquid level of the internal hydraulic oil, the hydraulic oil in the oil chamber that communicates with this hydraulic oil through the lubrication hole flows onto the sliding surface of the slide bush. It will surely spread.

The only sliding parts between the outer vibe and the inner pipe are the slide bush and guide bush, and since the sliding area is small, combined with the good lubrication mentioned above, the sliding resistance is significantly reduced, improving operability. will improve.

Figure 1 is a sectional view of a front fork according to an embodiment of the present invention, where 1, 1 is an aluminum alloy outer vibe, and 2 is an inner pipe. This front fork is Outer Vibe 1
It is mounted between the body frame and the front wheel of a two-wheeled vehicle, with the side (left side in the figure) facing upward and the inner pipe 2 side (right side in the figure) facing downward. In other words, it is an inverted front fork.

A bottom member 3 is fitted to the lower end of the inner pipe 2, and an axle 31 is connected to the bottom member 3 by front tightening. A brush caliber (not shown) is supported on the bracket 4 . The upper end of the outer vibe 1 is connected to a handle rotation shaft via a bracket (not shown).

The inner pipe 2 is inserted into and removed from the bottom of the outer vibe 1, but the outer diameter of the inner pipe 2 is smaller than the inner diameter of the outer vibe 1.
A slide bushing 5 fitted to the outer circumference of the upper end and a guide bush 6 fitted to the inner circumference of the lower end of the outer vibe 1
and these bushings 5.
6 and held coaxially. Therefore Outer Vibe 1
There is an annular gap or oil chamber 7 between the inner pipe 2 and the inner pipe 2.
is formed. Slide bush 5, guide bush 77
The housing 6 and the oil chamber 7 will be described in more detail later.

At the inner lower part of the inner pipe 2, attach the lower end to the photo 19 member 3.
The damper cylinder 8, which is fixed and closed, is connected to the inner pipe 2.
A damper piston 9 is provided coaxially with the damper cylinder 8, and a damper piston 9 is provided so as to be freely slidable. A damper rod 10 extends from the damper piston 9 in a sliding manner through a rod guide 11 fixed to the upper end of the damper cylinder 8 in the -F direction, and its upper end is fixed to the upper end of the outer vibe 1. The inside of the damper cylinder 8 passes through the oil [ ] 12 at the lower end to an oil reservoir chamber 1 formed between the inner pipe 2 and the damper cylinder 8 and opened upward.
I have an i7 connected to 3. Damper cylinder 8 and oil sump chamber 1
3 is filled with hydraulic oil, and this hydraulic oil forms an oil surface 14 within the upper outer vibe 1 .

The damper piston 9 divides the inside of the damper cylinder 8 into upper and lower cylinder chambers 15a and 15b. This damper piston 9 allows hydraulic oil to freely flow from the cylinder chamber 15b to the cylinder chamber 15a, but from the chamber 15a to the cylinder chamber 15a.
A one-way valve 16 that blocks the flow from the chamber 15a to the chamber 15b, and a throttle valve 17 that applies damping force by resisting the flow from the chamber 15a to the chamber 15b are provided.

A damper base valve 18 is provided below the damper cylinder 8 and above the oil port 12, and the damper base valve 18 is also provided with a similar one-way valve 19 and a throttle valve 20. A coil spring 22 is compressed between the oil lock collar 21 attached to the rod guide 11 and the upper end of the outer vibe 1, and due to the buffering action of the coil spring 22 and the damping action of the throttle valve 17.20, The impact that the wheels receive from the road surface is softened and transmitted to the vehicle body.

An oil lock piece 23 and a spring guide 24 are attached to the portion of the damper rod 10 extending from the damper cylinder 8.
is fitted. The oil lock piece 23 enters into the oil lock collar 21 when the inner pipe 2 enters the outer vibe 1 to the most contracted position of the front fork, and exerts a buffering effect by trapping the hydraulic oil in the oil lock collar 21. Spring guide 24
is made of resin and guides the inner circumferential surface of the coil spring 22 with a very small gap and always maintains it in a predetermined position.
It plays a role in preventing falls.

The outer circumferential surface of the slide bush 5 has an arcuate shape with a central portion bulging outward in an axial cross section, and is in sliding contact with the inner circumferential surface of the outer vibe 1 at the central portion. On the other hand, the guide bush 6 has an arcuate axial cross-sectional shape with an inner circumferential surface bulging inward, and is in sliding contact with the outer circumferential surface of the inner pipe 2 at its center. Therefore, since the area of the sliding portion between the outer vibe 1 and the inner pipe 2 is small, sliding resistance is small and good operability can be obtained. Further, even if the axes of the outer vibrator 1 and the inner pipe 2 deviate from each other to some extent, the arc-shaped peripheral surface can accommodate this deviation, and the operation will not be hindered.

The sliding surfaces of the slide bush 5 and guide bush 6, whose surfaces are treated with Teflon, are lubricated by hydraulic oil. For this purpose, a lubrication hole 25 is bored through the wall of the inner pipe 2, and an oil chamber 7 defined by the outer pipe 1, the inner pipe 2, the slide bush 5, and the guide bush 6 is formed. , communicates with the hydraulic oil inside the inner pipe 2 through this lubrication hole 25. The lubrication hole 25 is provided so as to be located below the raised oil level 14a even when the front fork is most contracted, that is, when the inner pipe 2 is at the uppermost position. Therefore, regardless of the position of the inner pipe 2, the supply of hydraulic oil to the oil chamber 7 is not interrupted, and the oil chamber 7 is always filled with hydraulic oil. The sliding surfaces between the guide bushing 6 and the inner pipe 2 are sufficiently lubricated.

As shown in FIG. 2, an oil groove 26 in the axial direction is formed on the outer peripheral surface of the slide bush 5, and the oil in the oil chamber 7 is uniformly distributed over the sliding surface through this oil groove 26. . The position of the slide bush 5 is also as shown by the broken line in FIG.
Even when the front fork is most retracted, it is positioned below the oil level 14, so that oil supply through the oil groove 26 is never interrupted. FIG. 3 shows another embodiment of the slide bush 5. This slide bush 5 has a spiral oil groove 26a carved in its outer peripheral surface.

As shown in FIG. 4, the inner peripheral surface of the guide bush 6 has
A circumferential oil groove 27 is carved. Guide bush 6
is provided on the outside of the inner pipe 2 at the lower end of the outer pipe 1, so the guide bush 6 has an oil groove 26 extending in the axial direction similar to the slide bush 5.
Alternatively, if the oil groove 26a is provided, the oil in the oil chamber 7 leaks to the outside through this oil groove. However, if the circumferential oil groove 27 is provided as described above, oil leakage can be effectively prevented. An oil seal 28 is further provided below the guide bush 6. This oil seal 28 is connected to a small seal case 2 integrally formed at the lower end of the outer vibe 1.
9 and is in sliding contact with the outer peripheral surface of the inner pipe 2. The lower opening of the sealing case 29 is further closed by a flexible cover piece 30.

As described above, in the present invention, an inverted front fork is comprised of an outer vibe and an inner pipe slidably inserted into the outer vibe, and is arranged with the outer vibe at the top and the inch vibe at the bottom. An oil chamber is formed between a guide bushing fitted to the lower end of the outer vibe and in sliding contact with the inner pipe and a slide bushing fitted to the upper end of the inner pipe and sliding in contact with the outer vibe. A lubrication hole communicating with the hydraulic oil is drilled in the inner pipe wall, and the slide bush and the lubrication hole are positioned below the level of the hydraulic oil when the front fork is retracted, so that the oil chamber is closed. is always filled with hydraulic oil regardless of the expansion and contraction of the front fork, and this hydraulic oil is reliably captured not only in the lower guide bushing but also in the upper slide bushing, and the sliding parts are sufficiently lubricated.

Furthermore, since the outer vibe and the inner pipe slide through a relatively small area of sliding contact, combined with the above-mentioned good lubrication, the sliding resistance is significantly reduced and the operability of the front fork is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a front fork according to an embodiment of the present invention, FIG. 2 is a side view of a slide bush, FIG. 3 is a side view of another embodiment of the slide bush, and FIG. FIG. 3 is a longitudinal cross-sectional view of the guide bushing. ■... Outer vibe, 2... Inner pipe, 3...
・Bottom member, 4... Bracket, 5... Slide bushing, 6... Guide bushing, 7... Oil chamber, 8
... Damper cylinder, 9 ... Damper piston, 10
...damper rod, e...rod guide, I2.
...Oil port, 13...Oil sump chamber, 14...Oil level, 15.
... Cylinder chamber, 16... One-way valve, 17... Throttle #)
Valve, 18... Damper base valve, 19... One-way valve, 20... Throttle valve, 2nd... Oil lock collar,
22... Coil spring, 23... Oil lock piece, 24... Spring guide, 25... Lubrication hole, 26.27... Oil groove, 28... Oil seal,
29...Seal case, 3o...Part of cover, 31
···axle.

Claims (1)

[Claims] In an inverted front fork that consists of an outer pipe and an inner pipe slidably inserted into the outer pipe, the outer pipe is placed above and the inner pipe is placed below, the guide bush is fitted into the lower end of the outer pipe and slides into contact with the inner pipe. and a slide bush that is fitted into the upper end of the inner pipe and slides into contact with the outer pipe, an oil chamber is formed between the inner pipe and the slide bush, and a lubricating hole is bored in the inner pipe wall to communicate the oil chamber with the internal hydraulic oil, and A front fork characterized in that the slide bush and the lubricating hole are located below the liquid level of the hydraulic oil when the front fork is contracted.