JP3446026B2 - Front fork - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork for a motorcycle, and more particularly to an improvement of a front fork mounted on a road racing motorcycle.

[0002]

BACKGROUND OF THE INVENTION Road racing motorcycles generally run on a flat road surface, but it is said that it is preferable that the vehicle body posture is maintained in a nose-dive tendency during cornering as compared to when traveling straight.

That is, when the vehicle is traveling straight, the extension side damping force of the front fork when compressed due to road surface vibration or the like is set to be small so that the vehicle body posture is quickly restored and steering stability is easily obtained. It will be good.

On the other hand, at the time of cornering, the extension side damping force of the front fork contracted by a large stroke due to the braking action or the like is set to be large so that the desired nose dive tendency is easily maintained until the cornering is completed. It would be good to

As far as the extension side damping force is concerned, various proposals have been made in the past as a front fork which meets the demand that the height of the extension side damping force is contradictory to the contraction stroke. The reality is that what is done is not provided.

The present invention was devised in view of the above-mentioned circumstances, and an object thereof is to provide a front fork which is most suitable for mounting on a motorcycle of a road race specification. .

In order to achieve the above object, the means of the present invention
The piston rod comes out through the piston in the cylinder.
It is inserted so that it can be retracted, and the piston is in the rod side chamber inside the cylinder.
And the piston side chamber, and the piston has a rod side chamber
The expansion side damping valve and the compression side chain that communicate with the piston side chamber
Equipped with a check valve, and the piston rod has the above damping on the extension side.
Bypass the valve to connect the rod side chamber and the piston side chamber.
Flow path forming a bypass path consisting of vertical holes and horizontal holes
For opening and closing the horizontal hole in the vertical hole,
A spool that can be freely moved downward and this spool is attached in the opening direction.
Insert the biasing spring in series, and
On the Tom side, raise the rod body that faces the vertical hole and the spool.
Upright and the piston is pushed beyond the normal stroke.
When the rod is stroked to the side, the rod body enters the vertical hole and
Urging the spool in the closing direction against the spring.
And are characterized by.

[0008] Specifically, for example, the outer tube is a vehicle body side tube and a piston rod is arranged in the shaft core portion thereof, and the inner tube is an axle side tube and a cylinder is mounted in the shaft core portion thereof. It will be distributed.

[0009]

Therefore, when the piston moves up and down in the cylinder with a normal stroke, the bypass passage is in communication during the expansion side operation, and the expansion side generated by the expansion side damping valve provided in the piston is generated. The damping force becomes low.

On the other hand, when the piston descends in the cylinder with a large stroke, a rod body disposed on the bottom side of the cylinder is provided in a vertical hole opened in the axial center of the piston rod so as to form a bypass passage. Is infiltrated and the bypass path is cut off.

Therefore, even when the piston is reversed to the extension side ascending in the cylinder, the bypass passage is blocked, and the extension side damping force generated by the extension side damping valve becomes high as set. Become.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the embodiment of the present invention will be described below with reference to the drawings.
To do. The front fork according to the present invention constitutes a damper
Piston rod in the cylinder 4 via the piston 5
3 is inserted so that it can be retracted, and the piston 5 is inserted into the cylinder 4.
The rod-side chamber A and the piston-side chamber B are partitioned, and the piston 5
On the extension side that connects the rod side chamber A and the piston side chamber B
A damping valve 7 and a pressure side check valve 8 are provided,
The rod 3 bypasses the extension side damping valve 7 and
Vertical hole 3a and lateral hole 3 for communicating the side chamber A and the piston side chamber B
It forms a bypass path consisting of c and c. And the present invention
Then, in the vertical hole 3a, the vertical moving unit that opens and closes the horizontal hole 3c.
Attach the existing spool 31 and this spool 31 in the opening direction.
Insert the spring 33 for urging in series,
The vertical hole 3a and the spool 31 on the bottom side of
The rod body 13 is raised and the piston 5 is
Above the rod when a large stroke is made to the compression side
The body 13 penetrates into the vertical hole 3a and resists the spring 33.
And pushes the spool 31 in the closing direction.
It This will be described in more detail below. In the front fork according to this embodiment, an inner tube 2 that is an axle side tube is inserted into an outer tube 1 that is a vehicle body side tube so that the inner tube 2 can be retracted, and the outer tube 1 has a piston rod at its axial center portion. 3, the inner tube 2 has a cylinder 4 at its axial center, as shown in FIG .

Although not shown, the piston rod 3 has a base end, which is an upper end thereof, integrally connected to the inside of the upper end of the outer tube 1. As shown in the drawing, the tip end side, which is the lower end side, is inside the cylinder 4. It is inserted so that it can appear and disappear.

Although not shown, the cylinder 4 is formed in a shaft-sealing structure so that the open end, which is the upper end, allows the piston rod 3 to be slidably inserted therein. 2 is slidably accommodated, and as shown in FIG. 2, it has a base valve portion 6 inside the bottom side end which is the lower end thereof.

As shown in FIG. 1, the piston 5 is formed by partitioning a rod side chamber A and a piston side chamber B in a cylinder 4, and the rod side chamber A and the piston side chamber B are arranged in the piston 5. The extension side damping valve 7 and the compression side check valve 8 can communicate with each other.

Further, as shown in FIG. 2, the piston side chamber B is outside the cylinder 4, that is, the cylinder 4 and the inner tube 2 via a compression side damping valve 9 and an expansion side check valve 10 arranged in a base valve portion 6. It is possible to communicate with a reservoir chamber C that is formed between and.

Incidentally, the lower end side of the base valve portion 6, that is,
An annular capacity chamber D is formed on the downstream side of the compression side damping valve 9, and the capacity chamber D is communicated with the reservoir chamber C through a communication hole 4a that is opened in the cylinder 4. It is said that communication between the piston side chamber B and the reservoir chamber C is realized.

Therefore, in the front fork formed as described above, when the inner tube 2 is retracted from the outer tube 1, the tip side of the piston rod 3 is retracted from the cylinder 4. become.

During the compression operation in which the piston 5 descends in the cylinder 4, the hydraulic oil from the piston side chamber B flows into the rod side chamber A via the pressure side check valve 8 in the piston 5.

At this time, the working oil corresponding to the intruding volume of the piston rod 3 flows out from the piston side chamber B into the reservoir chamber C via the pressure side damping valve 9 in the base valve portion 6.

When the hydraulic oil from the piston side chamber B passes through the compression side damping valve 9 in the base valve portion 6, a predetermined compression side damping force is generated.

In the front fork, when the piston 5 moves upward in the cylinder 4, the hydraulic oil from the rod side chamber A flows into the piston side chamber B through the expansion side damping valve 7 in the piston 5. To do.

When the hydraulic oil from the rod side chamber A passes through the extension side damping valve 7, a predetermined extension side damping force is generated.

Ascending of the piston 5 in the cylinder 4,
That is, the hydraulic oil that becomes insufficient in the rod side chamber B due to the withdrawal is transferred from the reservoir chamber C to the piston side chamber B via the extension side check valve 10 in the base valve portion 6.
Will be replenished.

By the way, in the front fork according to this embodiment, the expansion side damping valve 7 provided in the piston 5 is provided.
It has a bypass path that detours around, and is set so that the extension side damping force becomes high when the bypass path is blocked.

That is, the bypass path is, as shown in FIG.
Longitudinal hole 3 formed in the shaft core on the tip side of the piston rod 3
The vertical hole 3a has an upper end in the drawing, the upstream side end of which is opened in the radial direction of the piston rod 3 to form a bypass passage. It is in communication with A.

Incidentally, the vertical hole 3a has a downstream end, which is the lower end in the figure, which is basically opened at the tip of the piston rod 3 and is opened to the piston side chamber B. However, in the present invention, the spool 31 is slidably provided at the downstream end thereof and is closed at the tip of the piston rod 3.

The spool 31 is prevented from falling out of the vertical hole 3a by an annular stopper 32 that is press-fitted into the tip of the piston rod 3, while the spring 33 accommodated in the vertical hole 3a is used for drawing. It is urged in the forward direction, which is the downward direction.

The downstream path of the bypass passage is communicated with the piston side chamber B at a portion near the tip of the piston rod 3, that is, at a portion where the expansion side damping valve 7 of the piston 5 is crossed.

That is, the downstream side end of the vertical hole 3a constituting the bypass passage is radially opened at a portion near the tip of the piston rod 3 to the piston side chamber B via the lateral hole 3c also constituting the bypass passage. It is said that communication is possible.

Incidentally, the horizontal hole 3c is provided with the spool 31 when the spool 31 is in the lowest position (the state shown in FIG. 1) urged by the spring 33 in the vertical hole 3a.
The opening is set so as to be maintained unblocked.

Therefore, in the bypass passage according to this embodiment, when the spool 31 is lifted in the vertical hole 3a against the biasing force of the spring 33 to close the opening of the horizontal hole 3c and the spool 31. Is moved to the so-called upstream side of the opening of the horizontal hole 3c with a large stroke to move up in the vertical hole 3a, and thus, it is placed in the blocking state.

On the other hand, in this embodiment, a sub-valve 11 which also functions as a pressure side check valve is arranged at the downstream end of the bypass passage, and the sub-valve 11 is
As shown in FIG. 3, the annular window 1 formed on the upper end surface of the valve seat 12 interposed on the outer periphery of the tip end portion of the piston rod 3.
It is arranged so as to openably close 2a.

That is, the sub-valve 11 is formed of an annular leaf valve, and the inner peripheral end of the valve stopper 7a disposed on the rear side of the expansion side damping valve 7 is fixed to the inner peripheral end with the interposition of the spacer 11a. Is distributed to.

The outer peripheral end of the sub-valve 11 is a free end, and the outer peripheral seat portion 12 of the valve seat 12 is provided.
Adjacent to b, the annular window 12a is said to be openably closed.

On the other hand, the valve seat 12 has an annular groove 1 formed on its inner peripheral wall surface and communicating with the lateral hole 3c.
2c, and the annular groove 12c communicates with the annular window 12a through the notch groove 12d.

Therefore, in the sub-valve 11, the hydraulic oil from the vertical hole 3a forming the bypass passage is transferred to the horizontal hole 3c,
Through the annular groove 12c and the cutout groove 12d, it reaches the inside of the annular window 12a and lifts the outer peripheral side end of the sub-valve 11 to allow it to flow to the outside, that is, to the piston side chamber B.

On the other hand, the sub-valve 11 functions as a check valve by preventing the hydraulic oil from the piston side chamber B from flowing into the bypass passage in the reverse flow of the above.

Therefore, in this embodiment, the bypass passage functions as a bypass passage on the expansion side, and unless the bypass passage is closed, the expansion side damping valve 7 generates the expansion side. It will function to reduce the damping force.

Incidentally, when the bypass passage completely permits passage of the hydraulic oil, it is not possible to expect the generation of the damping force by the expansion side damping valve 7, so that the flow rate control of the hydraulic oil in the bypass passage is controlled. Must be realized.

The control of the flow rate of the hydraulic oil in the bypass passage is performed by, for example, the lateral hole 3b forming the bypass passage.
Alternatively, it may be due to the flow path resistance caused by the selection of the diameter of the lateral hole 3c, and further, a variable flow rate control valve operated by an external operation may be provided in the bypass path.

By the way, the bypass passage is closed when the spool 31 is raised against the biasing force of the spring 33 in the vertical hole 3a forming the bypass passage, as described above.

The spool 31 is raised in the vertical hole 3a against the urging force of the spring 33 when the piston 5 descends in the cylinder 4 with a large stroke. Is when the rod body 13 (see FIG. 2) arranged in the base valve portion 6 enters the vertical hole 3a as shown in FIG.

The rod body 13 in this embodiment is
As shown in FIG. 2, it is assumed that it is integrally connected to the fixed pin 14 that constitutes the base valve portion 6, and extends from the upper end of the fixed pin 14 to an appropriate length upward.

Incidentally, the thickness of the rod body 13 is set to such a size that the rod body 13 can be freely inserted through the inner peripheral side of the annular stopper 32, that is, a so-called hole, and the spool 31 is accommodated. The size is set so that the vertical hole 3a can be freely inserted.

It is needless to say that the rod body 13 is positioned so that its axis coincides with the axis of the cylinder 4, that is, the axis of the piston rod 3.

Therefore, as shown in FIG. 4, the rod body 13 has its upper end side intruding into the vertical hole 3a formed in the piston rod 3 when the piston 5 descends in the cylinder 4 with a large stroke. That is, the spool 31 accommodated in the vertical hole 3a is raised in the vertical hole 3a.

Then, the horizontal hole 3c forming the bypass passage is formed by the spool 3 rising in the vertical hole 3a.
1 is on the downstream side, that is, on the back side, and therefore,
The bypass will be closed.

Further, by closing the bypass passage, the sub-valve 11 is put into an inoperative state. Therefore, the extension side in which the piston 5 ascends in the cylinder 4 by reversing under the above condition. When activated, it is possible to generate a damping force set in the extension side damping valve 7, that is, a high damping force.

In the above-described embodiment, the piston rod 3 is arranged in the outer tube 1 which is a vehicle body side tube, and the cylinder 4 is arranged in the inner tube 2 which is an axle side tube. Alternatively, the cylinder 4 may be arranged in the outer tube 1 which is the vehicle body side tube, and the piston rod 3 may be arranged in the inner tube 2 which is the axle side tube.

Further, while the outer tube 1 is the axle side tube and the inner tube 2 is the vehicle body side tube, the piston rod 3 and the cylinder 4 are selectively arranged in the outer tube 1 or the inner tube 2. Is also good.

In any of the above cases,
Needless to say, the situation in which the expansion-side damping force is generated does not differ from that in the above-described embodiment.

[0053]

As described above, according to the present invention, when the piston moves up and down with a normal stroke in the cylinder, the bypass passage can be communicated with the extension side damping valve, especially during the extension side operation. It is possible to generate an extension side damping force lower than the set value.

Therefore, the compressed front fork can be quickly extended. Therefore, when the front fork is mounted on a motorcycle of a road race specification, generally, when traveling straight on a flat road surface, Since the body posture can be quickly restored, there is an advantage that steering stability can be easily obtained.

According to the present invention, when the piston moves up and down with a large stroke in the cylinder, the bypass passage is blocked, especially during the extension side operation.
The damping force generated by the extension side damping valve is set as the extension side damping force with a high setting.

Therefore, when a road-race type motorcycle equipped with the front fork is cornering, when the front fork is largely compressed, its return to the extension side tends to be delayed. There is an advantage that the vehicle body posture of the motorcycle is easily maintained in the nose dive tendency, and desired cornering can be effectively realized.

Further, according to the present invention, the spool which is housed in the vertical hole which constitutes the bypass passage and which makes the bypass passage in the closed state at the time of sliding thereof is only provided when the rod body enters the vertical hole. Since it is configured to slide, there is an advantage that the sliding of the spool can be reliable as compared with the case where it is configured to slide by so-called hydraulic pressure.

Further, according to the present invention, since the rod body is configured to be projected and retracted in the vertical hole formed in the axial center portion of the piston rod, modification for expanding the cylinder diameter is not required. There is also an advantage that the diameter of the entire front fork is not increased.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view showing a front fork according to an embodiment of the present invention centering on a piston portion.

FIG. 2 is a partial vertical cross-sectional view showing the front fork of FIG. 1 centering on a base valve portion.

FIG. 3 is a partial vertical cross-sectional view showing an enlarged piston portion of the front fork of FIG.

FIG. 4 is a partial vertical sectional view showing a state in which the front fork of FIG. 1 is compressed with a large stroke.

[Explanation of symbols]

1 Outerwear 2 Inner tube 3 piston rod 3a Vertical hole forming a bypass passage 4 cylinders 5 pistons 7 Extension side damping valve 13 Rod body 31 spool 33 spring A Rod side chamber B Piston side chamber

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16F 9/00-9/58 B62K 25/00-27/16

Claims (2)

(57) [Claims] Claim: What is claimed is: 1. A piston rod is mounted in a cylinder through a pist
The piston is inserted into the cylinder so that the piston can
It separates the head side chamber from the head side chamber, and
Expansion side damping valve that connects the chamber on the piston side and the chamber on the piston side
A pressure side check valve is provided, and the piston rod has the above
Bypass the extension side damping valve and connect the rod side chamber and the piston side chamber.
By forming a bypass path consisting of a vertical hole and a horizontal hole for communication
With a front fork that has
Up and down movable spool to close and open this spool
Insert a spring that biases in
On the bottom side of the connector facing the vertical hole and the spool.
Stand up and the piston goes beyond its normal stroke.
When making a large stroke to the pressure side, the rod body
Intrude and attach the spool in the closing direction against the spring
Front fork, characterized in that the energizing. 2. The outer tube is a vehicle body side tube and a piston rod is arranged on its shaft center portion, and the inner tube is an axle side tube and a cylinder is arranged on its shaft center portion. A front fork according to claim 1, characterized in that