JPH0717867Y2 - Front fork - Google Patents

Description

[Detailed Description of the Invention] [Prior Art and its Problems] Generally, a front fork in a running two-wheeled vehicle is
It expands and contracts smoothly within the normal stroke range, but when the front fork is compressed with an extremely large stroke, the oil lock effect is exerted by using the oil hole rod, so that the handle side of the motorcycle is not lowered more than necessary. Is formed in.

Therefore, stable maneuverability can be obtained not only in an on-road vehicle but also in an off-road vehicle, even when the maximum compression of the front fork is caused by sudden braking, riding on a protrusion, dropping, or the like.

However, the oil lock mechanism using the above oil hole rod is
When reversing from the compression side to the extension side, a negative pressure phenomenon is caused around the oil hole rod, and there is a disadvantage that smooth reversal to the extension side, that is, continuity cannot be obtained.

Therefore, for example, a structure of the oil hole rod portion as shown in FIG. 2 is proposed.

That is, the oil hole rod 3 is arranged inside the lower end of the outer tube 1 so as to surround the outer periphery of the base end of the seat pipe 2, and the outer tube 1 is attached to the sliding contact portion 3a on the outer periphery of the upper end of the oil hole rod 3. When the inner circumference of the lower end of the inner tube 4 which is inserted into the sliding contact is slidably contacted, the oil lock chamber R is provided around the oil hole rod 3.
Is partitioned.

On the other hand, a so-called inside of the oil hole rod 3 is provided with a flow path L, and a check valve 5 is provided at a downstream outlet of the flow path L.

That is, the partition wall 3b is formed so as to project in the middle portion of the inner peripheral wall of the oil hole rod 3, and the annular clearance a is provided below the partition wall 3b.

Further, the base portion 3c of the oil hole rod 3 is formed so as to largely extend in the horizontal direction so that the diameter thereof is larger than the diameter of the upper sliding contact portion 3a, and the above-mentioned gap a is formed on the lower surface near the inner periphery of the base portion 3c. It has an annular groove b communicating with.

The base portion 3c has a port c that penetrates the base portion 3c in the thickness direction (vertical direction in the drawing) and has a lower end opened to the groove b and an upper end opened to the oil lock chamber R.

Further, the gap a is communicated with a lower chamber B in the seat pipe 2 through a communication hole 2a formed in the seat pipe 2, and the port c has an upper end opening of the port c which is an upper oil lock chamber. It is supposed that the check valve 5 adjacent from the R side closes it.

That is, the check valve 5 allows the hydraulic oil from the lower chamber B to flow into the oil lock chamber R through the flow path L formed by the communication hole 2a, the gap a, the groove b, and the port c. Therefore, the check valve 5 blocks the reverse flow.

Therefore, as shown in the drawing, when the inner tube 4 approaches the maximum compression of the front fork that descends the most in the outer tube 1, the working oil is confined in the oil lock chamber R, and the desired oil lock effect is obtained. To be

However, as in the illustrated conventional example, the check valve 5
So as to face the lower end of the inner tube 4, that is,
If it is arranged on the outer peripheral side of the oil hole rod 3, the thickness of the thick portion of the base portion 3c protruding horizontally to form the port and the height dimension corresponding to the arrangement of the check valve 5 are the inner tube 4. However, there is a disadvantage that the basic length of the front fork is increased.

In addition, in forming the oil hole rod 3, not only is it necessary to form the partition wall portion 3b and the groove b for aligning the oil hole rod 3 with the seat pipe 2, but also to communicate with the seat pipe 2. Hole
In addition to 2b, an additional communication hole 2a has to be drilled, so-called machining process extends over many branches, and its accuracy control is also important. .

Furthermore, it is not suitable to use this oil lock mechanism for a front fork with a built-in damper.

That is, in a damper cylinder corresponding to a conventional seat pipe, a piston is slidably provided via a piston rod connected to an inner tube, and a damper side built-in type in which a compression side valve is provided below the damper cylinder during compression operation. When the above-mentioned oil lock mechanism is used for the front fork, the pressure side valve must be arranged above the through hole above the partition wall, which causes a problem that the damper itself becomes large in the longitudinal direction.

Therefore, in view of the above-mentioned circumstances, the object of the present invention is not only to obtain continuity when the oil lock state is reversed to the extension side, but also to limit the stroke of the inner tube at the time of maximum compression and to simplify the configuration. The purpose is to provide a front fork with a built-in damper that does not increase costs.

[Means for solving problems]

In order to achieve the above object, the configuration of the present invention is such that the vehicle body side inner tube is slidably fitted in the wheel side outer tube, and the damper cylinder is erected in the inner tube from the bottom side of the outer tube. , The piston part is slidably inserted into the damper cylinder through the piston rod connected to the inner tube, the base valve is provided inside the damper cylinder, and the oil hole rod is attached to the outer circumference below the damper cylinder. In the front fork with built-in damper, the oil hole rod has a thick base portion, and a pipe-shaped sliding contact portion that stands up from the outer peripheral side of the base portion and forms an upward flow path between the damper cylinder and the slide cylinder. The outer surface of the contact part consists of the sliding contact surface of the inner tube formed over the entire length, and the inside of the base of the oil hole rod is placed on the lower outer circumference of the cylinder. Fit, form a gap between the bottom surface of the base and the bottom of the outer tube,
A port that connects the flow passage and the gap is provided in the base portion, a check valve that allows only the flow from the flow passage is provided in the port opening, and an oil chamber below the base valve is provided in the damper cylinder. And a communication hole that communicates with the flow path.

[Action]

When the inner tube largely descends inside the outer tube and the inner periphery of the lower end of the inner tube comes into sliding contact with the sliding contact portion of the oil hole rod, an oil lock chamber is formed around the outer side of the oil hole rod. In addition, at this time, the check valve is closed to obtain the desired oil lock state,
Further lowering of the inner tube, that is, further compression of the front fork, is effectively suppressed.

When the inner tube is maximally lowered, the stroke of the inner tube is not limited because the base of the oil hole rod and the check valve are not provided on the line of the descending direction.

Further, when the inner tube is reversed from the maximum compression state and comes to come out from the oil hole rod, the check valve is opened and the working oil is quickly flowed into the oil lock chamber, so that the negative pressure phenomenon is not caused. Inversion is allowed smoothly.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

As shown in FIG. 1, a front fork according to an optimum embodiment of the present invention has an oil hole rod 30 outside a base end portion of a damper cylinder 20 standing upright in a wheel side outer tube 10. The vehicle body side inner tube 40 is inserted from above into the outer tube 10, the piston rod 50 is inserted into the inner tube 40, and the lower end of the piston rod 50 slides into the damper cylinder 20. It has a piston part 60 that is movably accommodated.

The outer tube 10 is arranged on the lower side, and is connected to the axle side in a motorcycle.

On the other hand, the inner tube 40 is on the upper side,
In the case of a motorcycle, it is connected to the handle side.

Although not shown, the upper end of the inner tube 40 and the upper end of the piston rod 50 are integrally connected, and the inside of the upper end of the inner tube 40 and the damper cylinder 20 are connected.
A suspension spring is housed between the upper end and the upper end.

Therefore, when an external force that compresses the front fork acts in the axial direction, the inner tube 40 is immersed in the outer tube 10,
When the front fork is contracted and the external force is released, the inner tube 40 is pushed up by the repulsive force of the suspension spring, and the front fork is extended.

The lower end of the damper cylinder 20 is screwed to the fastener 11 inserted through the central portion of the bottom portion 10a of the outer tube 10 and is erected inside the inner tube 40, and the upper end thereof is not shown. Although not provided, the piston rod 50 has a so-called sealed structure that allows the piston rod 50 to be inserted therethrough.

A base valve portion 70 is provided inside the lower end of the damper cylinder 20.
Is the mounting pin 11 of the fastener 11 in this embodiment.
It is supposed to be placed in a.

The lower oil chamber of the base valve portion 70 is formed outside, that is, between the outer tube 10 and the damper cylinder 20 via a communication hole 20a formed in the lower end portion of the damper cylinder 20. Is communicated with the reservoir chamber C.

The inside of the damper cylinder 20 is divided into an upper chamber A side and a lower chamber B side by the piston portion 60.

The upper chamber A and the lower chamber B are the piston parts.
The lower chamber B is communicated with the reservoir chamber C via the base valve portion 70.

The piston portion 60 is provided with an extension side damping valve 61 and a pressure side suction valve 62, and the base valve portion 70
A damping valve 71 on the compression side and a suction valve 72 on the extension side are arranged in the.

Therefore, when the piston portion 60 descends in the damper cylinder 20, a part of the hydraulic oil in the lower chamber B flows into the upper chamber A via the suction valve 62 of the piston portion 60 and the piston The working oil corresponding to the invasion volume of the rod 50 flows into the reservoir chamber C from the lower chamber B via the damping valve 71 of the base valve unit 70.

When the hydraulic oil passes through the damping valve 71,
A predetermined compression damping force is generated.

Further, when the piston portion 60 that has once descended rises in the damper cylinder 20, the hydraulic oil in the upper chamber A flows into the lower chamber B via the damping valve 61 of the piston portion 60, and In the chamber B, the hydraulic oil that is insufficient corresponding to the withdrawal volume of the piston rod 50 is the base valve portion 70.
Will be replenished from the reservoir chamber C via the suction valve 72.

When the hydraulic oil passes through the damping valve 61,
A predetermined extension side damping force is generated.

In the present embodiment, the damper cylinder 20 does not have the same diameter over its entire length.

That is, the diameter of the lower portion where the base valve portion 70 is arranged is smaller than the diameter of the portion of the piston portion 60 that allows vibration.

This is because it is generally desirable that the damping force characteristic of the front fork be smaller on the compression side than on the extension side. Diameter at the part where
That is, the diameter of the portion that influences the value of the extension side damping force is set to be larger than the diameter of the portion where the base valve portion 70 is disposed, that is, the diameter of the portion that affects the value of the compression side damping force. It was done.

Then, in the present embodiment, the pipe for the damper cylinder 20 having the diameter of the portion where the base valve 70 is arranged is positively expanded at the portion where the piston portion 60 slides. It is the one.

However, contrary to the case of the present embodiment, it goes without saying that the diameter of the portion of the base valve portion 70 may be reduced so as to be smaller.

Therefore, when the front fork according to the present invention is mounted on a so-called off-road vehicle, the shock at the time of plunging when overcoming continuous unevenness tends to be alleviated, and the stability of steering and riding The effect of improving comfort can be obtained.

The outer peripheral surface of the oil hole rod 30 is used as a sliding contact portion 30a, and when the upper inner tube 40 is lowered with a large stroke, the lower end inner circumference of the inner tube 40 is slidably contacted.

The inner circumference of the lower end of the inner tube 40 is the sliding contact portion.
An oil lock chamber R is defined in the outer lower portion of the oil hole rod 30 when the oil lock chamber R is slidably contacted.

The oil hole rod 30 has a base portion 30b that forms a thick bottom portion, a pipe-shaped sliding contact portion 30a that rises upward from the outer peripheral side of the base portion 30b, and the entire outer peripheral length of the sliding contact portion 30a is uniform. It consists of a smoothly formed sliding contact portion of the inner tube. The inside of the pipe-shaped sliding contact portion 30a is hollow and is opened upward. The inner circumference of the pipe-shaped sliding contact portion 30a and the damper cylinder 20 are
A flow path P having an upper opening is formed between the outer periphery and the outer periphery of the flow path P.

The inner inner circumference of the base portion 30b of the oil hole rod 30 is fitted to the smaller outer circumference of the damper cylinder 20 which is a cylinder. Base 30
The outer diameter of b may be smaller than the outer diameter of the sliding contact portion 30a.

The outer peripheral side lower surface of the small diameter portion provided downward from the base portion 30b of the oil hole rod 30 is a lower member, that is, the outer tube 10.
It is formed so as to face the bottom portion 10a with an appropriate gap S.

The inner peripheral side of the base portion 30b of the oil hole rod 30 is arranged so as to be sandwiched between the damper cylinder 20 and the bottom portion 10a. The base of the oil hole rod 30 when tightened and fixed with
30b is also supposed to be fixed at a predetermined position.

The base portion 30b of the oil hole rod 30 is provided with a port 30c so as to penetrate the wall thickness thereof, and the upper end of the port 30c is
The port 30c opens at the flow path P, and the lower end of the port 30c has the gap S.
And the port 30c communicates the flow path P with the gap S.

A check valve 80 is openably and closably arranged so as to close the lower end opening of the port 30c.

That is, the check valve 80 has an annular leaf valve 81, and an inner peripheral end of the leaf valve 81 is provided with a stop ring 82.
It is said that it is fixedly fixed by use and the bending of the outer peripheral edge is allowed.

In the present embodiment, the annular leaf valve 81 is
Although it is said that the stop ring 82 is used for fixing at a predetermined position, instead of this, the inner peripheral end of the annular leaf valve 81 is fitted into the small-diameter portion of the base portion 30b of the oil hole rod 30 so as to be fixed and fixed. You may allow it.

Therefore, when the inner tube 40 descends in the outer tube 10 with a large stroke, and the inner periphery of the lower end thereof comes into sliding contact with the sliding contact portion 30a of the oil hole rod 30, the check valve 80 is closed to close the oil hole. When an oil lock state is brought into the oil lock chamber R outside the rod 30, and when the inner tube 40 comes out of the oil hole rod 30 by reversing from the oil lock state, that is, inside the outer tube 10. When it goes up, the hydraulic oil from the reservoir chamber C side flows into the oil lock chamber R side under the opening of the check valve 80 via the oil passage P and the port 30c, so that the hydraulic oil enters the oil lock chamber R side. The above reversal is smoothly performed without causing a negative pressure phenomenon. That is, continuity from the pressure side operation to the extension side operation can be obtained.

In the oil lock stroke on the pressure side, the lower end of the inner tube 40 can be brought into sliding contact with the sliding contact surface 30a which is substantially the entire length of the oil hole rod 30, so that the inner tube 4
The situation where the oil hole rod 30 limits the stroke of 0 is not brought about.

In the above-described embodiment, the piston portion 60 and the base valve portion 70 are not formed so as to change and adjust the generated damping force, but instead of this, either one or both of them is generated. It goes without saying that the damping force may be changed and adjusted.

Further, although the front fork of the present invention has been described as being most suitable for so-called off-road in the above-mentioned embodiment, it is needless to say that it can be used for so-called on-road.

[Effect of device]

 As described above, the present invention has the following effects.

The oil hole rod has a base portion and a sliding contact portion, the inside of the base portion is fitted into the damper cylinder, and the sliding contact portion stands up from the outer peripheral side of the base portion, so that it interferes with this inner tube on the outer periphery of the oil hole rod. There is nothing. Therefore, the stroke of the inner tube at the time of maximum compression is not limited, and there is an advantage that the entire length can be shortened while ensuring a predetermined basic length.

When the inner tube largely descends inside the outer tube and the inner circumference of the lower end of the inner tube comes into sliding contact with the sliding contact portion of the oil hole rod, an oil lock chamber is formed around the outer side of the oil hole rod. And at this time,
The check valve is closed to obtain the desired oil lock condition, and further lowering of the inner tube, that is, further compression of the front fork is effectively suppressed. Further, when the inner tube is reversed from the maximum compression state and comes to come out from the oil hole rod, the check valve is opened and the working oil is quickly flowed into the oil lock chamber, so that the negative pressure phenomenon is not caused. Inversion can be done smoothly.

Since the oil hole rod is composed only of the base part where the port is formed and the pipe-shaped sliding contact part that rises upward from the outer peripheral side of this base part, it is possible to significantly reduce the number of processing steps, and it is possible to reduce the cost. There is an advantage that can be expected to be suppressed.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a front fork according to an optimum embodiment of the present invention, and FIG. 2 is a sectional view partially showing a conventional front fork. 10 …… Outer tube, 20 …… Damper cylinder, 20
a …… Communication hole, 30 …… Oil hole rod, 30a …… Sliding contact part, 30b ……
Base, 30c ... port, 80 ... check valve, 81 ... annular leaf valve, S ... clearance, P ... oil passage.

Claims (1)

[Scope of utility model registration request] 1. A vehicle body-side inner tube is slidably fitted in a wheel-side outer tube, and a damper cylinder stands up in the inner tube from the bottom side of the outer tube. In the front fork with built-in damper, in which the piston part is slidably inserted through the connected piston rod, the base valve is provided inside the damper cylinder, and the oil hole rod is attached to the outer circumference below the damper cylinder. The hole rod is formed over a thick base portion, a pipe-shaped sliding contact portion that stands up from the outer peripheral side of the base portion and forms a flow path that opens upward between the damper cylinder and the entire outer surface of the sliding contact portion. The inner surface of the oil hole rod is fitted to the lower outer circumference of the cylinder, and Form a gap between the bottom of the
A port that connects the flow passage and the gap is provided in the base portion, a check valve that allows only the flow from the flow passage is provided in the opening portion of this port, and an oil below the base valve is provided in the damper cylinder. A front fork with a built-in damper provided with a communication hole that communicates between the chamber and the flow path.