JPH0989033A - Front fork for bicycle or the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To well eliminate a negative pressure in an upper part oil chamber by arranging a disk valve through a clearance opposed to an opening of a piston hole in a lower surface side of a piston, deflection deforming this disk valve when a front fork is most compressed, and closing the opening of the piston hole. SOLUTION: In a compression process of a front fork, a check valve 48 is placed in an opened condition, operating oil in a lower part oil chamber 44 flows in an upperpart oil chamber 43 via a piston hole 47 of a piston 42 and via an annular flow path 56 between the piston 42 and a hollow pipe 34, and a negative pressure is eliminated. At extension time from a most compressed condition of the front fork, deflection deformation of a disk valve 52 is released, but the piston hole 47 of the piston 42 is closed by the check valve 48. Accordingly, operating oil in the piston 42 flows, via the check valve 48 and an annular flow path 56 between the piston 112 and the hollow pipe 34, into the lower part oil chamber 44 serving as an oil lock chamber, and the negative pressure is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork of a motorcycle or the like having an improved oil lock mechanism.

[0002]

2. Description of the Related Art In a front fork of a motorcycle, an oil lock collar 3 is installed at a tip portion of an inner tube 2 and a bottom portion of an outer tube 4 as in a device disclosed in Japanese Utility Model Publication No. 2-44119 shown in FIG. Oil lock piece 5
Is installed, and the oil lock collar 3 is fitted to the oil lock piece 5 when the front fork 1 is most compressed, and the oil lock chamber 6 is formed, so that further compression of the inner tube 2 is stopped.

Further, in a front fork 10 as shown in FIG. 4, which is disclosed in Japanese Utility Model Laid-Open No. 56-119789, a hollow pipe 14 having an expanded diameter portion 13 is erected on the bottom of an outer tube 11. A piston 15 installed at the tip of the inner tube 12 divides the oil chamber on the outer periphery of the hollow pipe 14 into an upper oil chamber 16 and a lower oil chamber 17, and the hollow pipe 14 has a reservoir inside the hollow pipe 14. A first oil hole 19 that connects the chamber 18 and the lower oil chamber 17 is formed, and a second oil hole 20 that connects the reservoir chamber 18 and the upper oil chamber 16 is formed.

During the compression process of the front fork 10, the hydraulic oil in the lower oil chamber 17 flows into the reservoir chamber 18 through the first oil hole 19 to generate a damping force on the compression side. At the time of maximum compression of the front fork 10, the piston 15 of the inner tube 12 closes the first oil hole 19 and the lower oil chamber 17 serves as an oil lock chamber, and further compression of the inner tube 12 is stopped.

[0005]

However, the front fork 1 shown in FIG. 3 requires the oil lock piece 5 on the outer tube 4, and the oil lock piece 5 is required.
In order to prevent the galling phenomenon with the oil lock collar 3, high processing precision and assembling precision such as matching the oil lock collar 3 with the shaft center are required.

Further, in the front fork 10 shown in FIG. 4, a check valve 21 which is opened in the compression process of the front fork 10 is installed in the expanded diameter portion 13 of the hollow pipe 14, and in the compression process of the front fork 10, The hydraulic oil in the reservoir chamber 18 flows into the upper oil chamber 16 whose volume is increased through the check valve 21 and the second oil hole 20. Although the negative pressure in the upper oil chamber 16 is released by the inflow of the hydraulic oil, the inflow of the hydraulic oil is caused by the inflow of the hydraulic oil.
Since it is based only on the negative pressure of, the amount of inflowing hydraulic oil may be insufficient, and there is a possibility that the negative pressure of the upper oil chamber 16 in the compression process of the front fork 10 cannot be satisfactorily canceled.

The object of the present invention has been made in view of the above circumstances, and it is possible to provide an oil lock mechanism having a simple and inexpensive structure, and to make the negative pressure of the upper oil chamber good in the compression process of the front fork. It is to provide a front fork for a motorcycle or the like that can be solved.

[0008]

According to a first aspect of the present invention, an inner tube connected to a vehicle body slides inside an outer tube connected to an axle side, and an inner tube is attached to a bottom portion of the outer tube. A hollow pipe having an enlarged diameter portion that slidably contacts the inner circumference is erected, and a piston that partitions the oil chamber outside the hollow pipe into an upper oil chamber and a lower oil chamber is installed on the inner circumference of the tip end portion of the inner tube. , A reservoir chamber is defined inside the hollow pipe, and the hollow pipe has
In a front fork of a motorcycle or the like in which an oil hole that communicates the reservoir chamber and the lower oil chamber is formed, the upper oil chamber and the lower oil chamber are provided between the inner circumference of the piston and the outer circumference of the hollow pipe. An annular flow path that connects the
A piston hole that allows the upper oil chamber and the lower oil chamber to communicate with each other is formed in the piston, and a check valve that opens the piston hole in the compression process of the front fork is arranged on the piston hole side of the piston. Is
A disc valve is arranged on the lower surface side of the piston so as to face the opening of the piston hole with a gap therebetween, and the disc valve is flexibly deformed when the front fork is compressed most to close the opening of the piston hole. It is a thing.

According to a second aspect of the invention, in the invention of the first aspect, the disc valve is configured such that the outer peripheral end thereof is fixed and the inner peripheral end side thereof is flexibly deformable.

The invention described in claims 1 and 2 has the following effects. A disc valve is configured to be able to close the piston hole of the piston installed at the tip of the inner tube, and this disc valve functions as a conventional oil lock piece installed at the bottom of the outer tube. Since this disc valve has a simpler and cheaper structure than the conventional oil lock piece, it is possible to provide an oil lock mechanism having a simple and inexpensive structure.

In the compression process of the front fork,
After passing through the piston hole of the piston provided at the tip of the inner tube and the check valve in the open state, and further through the annular flow path between the inner circumference of the piston and the outer circumference of the hollow pipe, the working oil in the lower oil chamber Guided to the oil chamber. As mentioned above,
Since the working oil positively flows into the upper oil chamber from the lower oil chamber whose volume decreases in the compression process of the front fork through the piston hole and the annular flow passage, a sufficient amount of oil is supplied to the upper oil chamber. Hydraulic fluid is introduced. As a result, the negative pressure in the upper oil chamber during the compression process of the front fork can be favorably eliminated.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic vertical sectional view showing an embodiment of a front fork of a motorcycle or the like according to the present invention. FIG. 2 is an enlarged cross-sectional view showing a part of FIG. 1 in an enlarged manner.

The front fork 30 shown in FIG. 1 is an upright front fork, and an inner tube 32 is slidably inserted into an outer tube 31 so that both tubes 31
A suspension spring 33 and a hollow pipe 34 that functions as a damper are arranged between the first and second parts 32 and 32. An axle (not shown) is supported in the axle hole 35 of the outer tube 31,
The inner tube 32 is connected to a body frame (not shown).

The hollow pipe 34 is fixed to the bottom portion 36 of the outer tube 31 by a center bolt 37 in an upright state. On the tip side of the hollow pipe 34, the ring body 3
8 is fitted and the enlarged diameter portion 39 that is in sliding contact with the inner peripheral surface of the inner tube 32 is integrally formed.

The suspension spring 33 has its lower end supported by the expanded diameter portion 39 of the hollow pipe 34, and its upper end supported by a fork cap (not shown) screwed to the upper end of the inner tube 32. , It absorbs the impact from the road surface.

The front fork 30 is filled with hydraulic oil inside the outer tube 31 and the inner tube 32, and the inside of the hollow pipe 34 is defined as a reservoir chamber 40. Here, reference numeral 41 in FIG. 1 indicates an oil level.
A piston 42 is installed at the lower end of the inner tube 32, and the piston 42 divides the oil chamber outside the hollow pipe 34 into an upper oil chamber 43 and a lower oil chamber 44.

The hollow pipe 34 has a first oil hole 45 formed at the lower portion thereof for communicating the reservoir chamber 40 and the lower oil chamber 44, and an upper portion for communicating the reservoir chamber 40 with the upper oil chamber 43. 2 The oil hole 46 is opened. These first oil holes 4
A plurality of the fifth oil holes 46 and the second oil holes 46 are formed along the axial direction of the hollow pipe 34. As will be described later, these first oil holes 4
Due to the damping force generated in the fifth oil hole 46 and the second oil hole 46, the contraction movement of the outer tube 31 and the inner tube 32 that occurs due to the absorption of the impact force by the suspension spring 33 is suppressed.

As shown in FIG. 2, the piston 42 is formed with a plurality of piston holes 47 which allow the upper oil chamber 43 and the lower oil chamber 44 to communicate with each other.
A check valve 48 is disposed on the upper surface side of the. The check valve 48 includes a ring-shaped valve body 48A,
The valve protrusions 48B are provided at predetermined intervals in the circumferential direction from one side surface of the valve body 48A. The valve protrusion 48B of the check valve 48 is supported by the valve stopper 50 locked to the inner tube 32 via the valve spring 49. The check valve 48 holds the piston hole 47 in a closed state by the urging force of the valve spring 49, but in the compression process of the front fork 30, the check valve 48 is opened by the pressure of the hydraulic oil flowing through the piston hole 47. The upper end opening 47A of the piston hole 47 is opened.

On the other hand, on the lower surface side of the piston 42, a disc valve 52 is arranged facing the lower end opening 47B of the piston hole 47 and having a gap 51 therebetween. The outer peripheral portion 53 of the disc valve 52 is clamped and fixed between the bent tip portion of the inner tube 32 and the piston 42 by using a shim 55. Then, the inner peripheral portion 5 of the disc valve 52
4 is configured to be flexibly deformable. Front fork 30
At the time of maximum compression, the pressure in the lower oil chamber 44 increases extremely as will be described later, and this pressure causes the inner peripheral portion 54 of the disc valve 52 to flex and deform, and the lower end opening 47 of the piston hole 47.
Block B.

An annular flow passage 56 is formed between the inner peripheral surface of each of the piston 42 and check valve 48 and the outer peripheral surface of the hollow pipe 34 to connect the upper oil chamber 43 and the lower oil chamber 44. .

Reference numeral 57 in FIG. 1 denotes a rebound spring, which comes into contact with the expanded diameter portion 39 of the hollow pipe 34 when the front fork 30 is fully extended, and absorbs the impact at the maximum extension.

A bush 58 for guiding sliding of the outer tube 31 and the inner tube 32 is disposed on the inner circumference of the opening of the outer tube 31, and this bush 58 is provided.
An oil seal 59 is attached in the vicinity of. The oil seal 59 is sandwiched between the outer tube 31 by a washer 60 and a stopper ring 61, and a dust seal 62 is further installed adjacent to the oil seal 59.

Next, the operation will be described. In the compression process of the front fork 30, the check valve 48 is opened, the working oil in the lower oil chamber 44 flows into the upper oil chamber 43 through the piston hole 47 of the piston 42, and the piston 42 and Via the annular flow path 56 between the hollow pipe 34 and
The hydraulic oil in the lower oil chamber 44 flows into the upper oil chamber 43.
Further, the hydraulic oil in the reservoir chamber 40 flows into the upper oil chamber 43 via the second oil hole 46. The negative pressure in the upper oil chamber 43, which increases in volume, is released by such an inflow of hydraulic oil.

In the compression process of the front fork 30, the upper part of the outer circumference of the hollow pipe 34, the lower oil chambers 43, 4
The inner tube 32 enters the inside of the reservoir 4, and the working oil corresponding to the entering volume flows into the reservoir chamber 40 through the first oil hole 45. A damping force is generated on the compression side by the resistance while the hydraulic oil passes through the first oil hole 45.

In the above compression process of the front fork 30, the plurality of first oil holes 45 are gradually closed by the piston 42, and when the front fork 30 is most compressed, the piston 42 closes the first oil hole 45 located at the lowest position. To do. At this time, the pressure in the lower oil chamber 44 extremely rises, the disk valve 52 flexes and deforms, and the piston hole 4 of the piston 42
Close 7. As a result, the hydraulic oil in the lower oil chamber 44 is almost trapped, and this lower oil chamber 44 serves as an oil lock chamber, and further compression of the inner tube 32 is stopped. Due to the oil lock function of this oil lock chamber,
Collision between the lower end portion of the inner tube 32 and the bottom portion 36 of the outer tube 31 is avoided.

At the time of the oil lock, the working oil in the lower oil chamber 44 serving as the oil lock chamber passes through only the annular flow path 56 between the piston 42 and the hollow pipe 34 into the upper oil chamber 43. Because it flows, the front fork 30
The shock at the time of the most compression of is relaxed.

On the other hand, in the process of extending the front fork 30, the check valve 48 moves the piston hole 4 of the piston 42.
Since 7 is closed, the hydraulic oil in the upper oil chamber 43 flows into the reservoir chamber 40 via the second oil hole 46. Also, the upper oil chamber 4
The hydraulic oil in 3 is the piston 42 and the check valve 48.
And the hollow pipe 34 through the annular flow path 45 to the piston lower oil chamber 44. The second oil hole 46 and the annular flow path 56
A damping force on the extension side is generated due to the resistance of the hydraulic oil flowing through.

In the process of extending the front fork 30, the inner tube 32 withdraws from the upper oil chamber 43, and the hydraulic oil equivalent to the withdrawal volume passes from the reservoir chamber 40 to the lower oil chamber 44 through the first oil hole 45. And the negative pressure in the lower oil chamber 44 is released.

When the front fork 30 is extended from the most compressed state, the flexural deformation of the disc valve 52 is released, but since the check valve 48 closes the piston flow path 47 of the piston 42, the hydraulic oil in the piston 42 is closed. But,
Check valve 48, piston 42 and hollow pipe 34
Through the annular flow path 56, and flows into the lower oil chamber 44 as an oil lock chamber, and the negative pressure in the lower oil chamber 44 is released.

According to the above-mentioned embodiment, the piston hole 4 of the piston 42 installed at the tip portion of the inner tube 32.
7 is configured so that a disc valve 52 can be closed, and the disc valve 52 functions as the conventional oil lock piece 5 (FIG. 3) installed on the bottom portion 36 of the outer tube 31. Since the disc valve 52 has a simpler structure and is less expensive than the conventional oil lock piece 5 (FIG. 3), an oil lock mechanism having a simple and inexpensive structure can be provided.

In the compression process of the front fork 30, the piston hole 47 of the piston 42 provided at the tip of the inner tube 32 and the check valve 4 in the open state.
8 and further through an annular flow path 56 between the inner circumference of the piston 42 and the outer circumference of the hollow pipe 34, through the lower oil chamber 4
The hydraulic oil in 4 is guided to the upper oil chamber 43, and also from the reservoir chamber 40, the hydraulic oil is guided to the upper oil chamber 43 through the second oil hole 46 of the hollow pipe 34. As described above, in the compression process of the front fork, the working oil positively flows into the upper oil chamber 43 from the lower oil chamber 44 whose volume decreases, through the piston hole 47 and the annular flow path 56. A sufficient amount of hydraulic oil is introduced into the upper oil chamber 43. As a result,
Upper oil chamber 43 in the compression process of the front fork 30
The negative pressure of can be satisfactorily eliminated.

The check valve 48 and the piston 42
The second oil hole 46 can be omitted by setting the inner peripheral annular flow path 56 to an appropriate size. Also, the first
Although a plurality of oil chambers 45 have been described, a single oil chamber may be used.

[0033]

As described above, according to the front fork of the motorcycle or the like according to the present invention, it is possible to provide an oil lock mechanism having a simple and inexpensive structure, and to reduce the negative pressure of the upper oil chamber during the compression process of the front fork. Can be resolved satisfactorily.

[Brief description of drawings]

FIG. 1 is an almost entire vertical cross-sectional view showing one embodiment of a front fork of a motorcycle or the like according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a part of FIG. 1 in an enlarged manner.

FIG. 3 is a partial cross-sectional view showing a conventional front fork.

FIG. 4 is a partial cross-sectional view showing another conventional front fork.

[Explanation of symbols]

 30 Front Fork 31 Outer Tube 32 Inner Tube 34 Hollow Pipe 36 Bottom 39 Expanded Area 40 Reservoir Chamber 42 Piston 43 Upper Oil Chamber 44 Lower Oil Chamber 45 First Oil Hole 46 Second Oil Hole 47 Piston Hole 48 Check Valve 47B Lower End Opening 51 gap 52 disc valve 53 outer peripheral part of disc valve 54 inner peripheral part of disc valve 56 annular flow path

Claims (2)

[Claims] 1. A hollow pipe having an inner tube connected to the vehicle body that slides inside an outer tube connected to an axle side, and a bottom portion of the outer tube having an enlarged diameter portion that slidably contacts the inner circumference of the inner tube. Is installed upright, a piston that partitions the oil chamber outside the hollow pipe into an upper oil chamber and a lower oil chamber is installed on the inner circumference of the tip end portion of the inner tube, and a reservoir chamber is defined inside the hollow pipe. In a front fork of a motorcycle or the like in which an oil hole that communicates the reservoir chamber and the lower oil chamber is formed in the hollow pipe, the upper oil is interposed between the inner circumference of the piston and the outer circumference of the hollow pipe. An annular flow path that communicates the chamber and the lower oil chamber is formed, a piston hole that allows the upper oil chamber and the lower oil chamber to communicate is formed in the piston, and the piston A check valve that opens the piston hole in the compression process of the front fork is arranged on the piston hole side, and a disc valve is arranged on the lower surface side of the piston facing the opening of the piston hole with a gap therebetween. A front fork for a motorcycle or the like, wherein the valve is flexibly deformed when the front fork is compressed most to close the opening of the piston hole. 2. The disk valve is configured such that an outer peripheral end thereof is fixed and an inner peripheral end side thereof is flexibly deformable.
Front forks for motorcycles, etc.