JPH07257468A - Vehicle height adjusting device of front fork for motorcycle - Google Patents

Abstract

PURPOSE:To properly hold extension-limit shock absobing ability in the respective case corresponding to vehicle height adjusting a motorcycle use front fork and to changing an effective stroke according to this height adjusting. CONSTITUTION:Spacers 24, which can be fitted to a peripheral surface of a center rod 7 extended along the axial center from an outer tube 2 and further can be arranged in series even between a suspension spring and a supporting part of the suspension spring, are used. By providing the spacers 24 selectively transferred between a side of the center rod 7 and a side of the suspension spring, a supporting position of the suspension spring and a position of the longest extension of an inner tube 6 can be simultaneously adjusted. Further, according to transfer providing the spacer 211 to a side of the center rod 7, simultaneously an opening area of a damping force generating orifice 19, provided in the center rod 7, is controlled by the spacer 24.

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 elastically supporting a front wheel of a motorcycle, and more specifically, a front for a motorcycle capable of changing an effective stroke according to the height of a vehicle body of the motorcycle. The present invention relates to improvement of a vehicle height adjusting device for a fork.

[0002]

2. Description of the Related Art Conventionally, as a vehicle height adjusting device for a front fork for a motorcycle of the same type, for example, one disclosed in Japanese Utility Model Application Publication No. 58092 of 1988 is known.

That is, in this device, a slider is movably screwed to the tip of a center rod extending from the outer tube along the axis, and the outer peripheral wall of the slider is brought into sliding contact with the inner wall of the inner tube.

Further, one end of the suspension spring is supported by the tip of the slider, and the lower end is opposed to the piston on the inner tube side so that the slider extends the most extended position of the inner tube.

Thus, the maximum extension position of the inner tube by the slider is also changed in association with the change of the support position of the suspension spring due to the movement of the slider, and the effective stroke of the front fork is also changed according to the ground height of the vehicle body. I am trying.

[0006]

As described above, in the conventional one, according to the difference in body size and preference of the rider,
Alternatively, it is suitable for on-road running on a flat road surface and off-road running for running on a rough road with continuous irregularities like sports, to lower the vehicle height and to shorten the effective stroke relatively, or At the same time as raising the vehicle height, the effective stroke is lengthened so that it is possible to drive in accordance with each.

However, in the above case, even if the vehicle height and the effective stroke are changed in accordance with the respective running conditions, the damping force characteristic is constant because the opening area of the damping force generating orifice is unchanged. .

For this reason, the opening area of the damping force generating orifice is set so as to be able to sufficiently absorb the extension impact input during traveling, based on the use when the effective stroke is set to be long at a high vehicle height. If the damping force characteristics are defined, there is a disadvantage in that the ability to absorb the extension impact at the time of use when the effective stroke is set to be short at a low vehicle height is insufficient, and a large extension impact occurs to impair the riding comfort.

On the other hand, if the opening area of the damping force generating orifice is set according to the extension impact input when the effective stroke is set to be short at a low vehicle height, this time, the effective stroke is set to a high vehicle height. When set to a long value, the damping force characteristics at the time of use become too high, which deteriorates the road holding performance and impairs running stability.

Therefore, an object of the present invention is to change the damping force characteristics in accordance with the vehicle height adjustment and the change in the effective stroke accompanying the vehicle height adjustment, and to appropriately maintain the damping force characteristics and the extension impact absorbing ability in each case. It is an object of the present invention to provide a vehicle height adjusting device for a front fork for a motorcycle that can be manufactured.

[0011]

SUMMARY OF THE INVENTION In the present invention, the above-mentioned object can be fitted to the outer peripheral surface of the center rod extending from the outer tube along the axial center, and the suspension spring and the supporting portion of the suspension spring. Spacers that can be arranged in series are also used between.

By selectively moving the spacer between the center rod side and the suspension spring side, both the support position of the suspension spring and the most extended position of the inner tube can be adjusted at the same time.

Further, in addition to the above, this is achieved by controlling the opening area of the damping force generating orifice provided in the center rod by the spacer when the spacer is moved to the center rod side.

[0014]

In other words, by adopting the above construction, when assembling work requires a long effective stroke at a high vehicle height, the spacer is mainly placed on the suspension spring side, and a low effective stroke at a low vehicle height is required. If so, select them on the center rod side and assemble them.

As a result, in the former case, the supporting height of the inner tube with respect to the outer tube is increased by the height of the spacer, and moreover, the restricting portion for determining the maximum extension position of the inner tube is moved upward by the absence of the spacer. Move to.

Further, in the latter case, the supporting height of the inner tube with respect to the outer tube is lowered by an amount corresponding to the absence of the spacer, and the restricting portion for determining the maximum extension position of the inner tube is lowered by the height of the spacer.

Therefore, the front fork assembled by the former is effective while keeping the vehicle body of the motorcycle at a high vehicle height, and the front fork assembled by the latter is effective while keeping the vehicle body of the motorcycle at a low vehicle height. The stroke is also shortened.

In addition, in addition to these, the spacer increases or decreases the opening area of the extension side damping force generating orifice so that the damping force characteristics of the front fork and the extension impact absorbing ability are appropriately maintained in accordance with each case. become.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a state in which the front fork 1 is assembled for an off-road vehicle. Here, for convenience of explanation, only one pair of left and right cushioning cylinders having the same structure will be described.

The front fork 1 includes an outer tube 2 and bearings 3 in the outer tube 2.
4 and the inner tube 6 slidably inserted through the seal 5, and the inner tube 6 from the lower bottom of the outer tube 2.
It has a hollow-pipe-shaped center rod 7 extending inside, and a suspension spring 8 interposed between the inner tube 6 and the center rod 7.

The outer tube 2 supports a front wheel of a two-wheeled vehicle by a bracket 9 provided at a lower portion thereof, and the inner tube 6 has a pair of upper and under brackets (not shown) attached to an upper portion thereof with a constant interval. Is steerably connected to the motorcycle body.

Thus, the front fork 1 elastically supports the front wheel vertically and movably with respect to the vehicle body of the two-wheeled vehicle by the suspension spring 8 through the outer tube 2 and the inner tube 6.

A piston 11 and a lock piece 12 are fixed to the inner periphery of the lower portion of the inner tube 6 with a spacer 10 interposed therebetween. The piston 11 defines an oil chamber A in the outer tube 2 and the inner tube 6 1 provided on the enlarged diameter portion 7a of the upper end of the center rod 7 in sliding contact with the inner wall of the
The oil chamber B is defined by 3 and the expanded diameter portion 7a.

The upper end surface of the piston 11 has a center rod 7
A buffer spring 14 is provided between the upper end surface of the piston 11 and the lower end surface of the expanded diameter portion 7a to face the lower end surface of the expanded diameter portion 7a of the front fork 1 for absorbing the shock when the front fork 1 is extended. There is.

The piston 11 is provided internally with a valve 15 which is in sliding contact with the outer peripheral wall of the center rod 7, and the valve 15 allows only the flow of hydraulic oil from the oil chamber A to the oil chamber B. .

Further, the lock piece 12 cooperates with the lock case 16 arranged on the outer peripheral portion of the base end of the center rod 7, and when the inner tube 6 is largely pushed into the outer tube 2, When fitted, the oil chamber A is put into an oil lock state to prevent the phenomenon of bottoming at the time of maximum compression.

The inside of the inner tube 6 and the center rod 7 is a storage chamber C for the hydraulic oil. The storage chamber C has an oil hole 17 formed in the center rod 7 and a pressure side provided under the center rod 7. Each of the oil chambers A and B communicates with the oil chamber B via the damping force generating valve 18, and also through a plurality of expansion side damping force generating orifices 19 arranged in the axial direction with respect to the center rod 7. It is designed to communicate.

In this embodiment, the orifice 19 for generating the extension side damping force is divided into a plurality of parts.
Of course, it may be configured as one or more elongated holes along the axial direction.

As a result, during the compression stroke in which the inner tube 6 is pushed into the outer tube 2,
The hydraulic oil in the oil chamber A is pushed into the oil chamber B by pushing the valve 15 of the piston 11 open, and at the same time, the oil hole 17 or the compression side damping force generating valve 18 is also pushed open and pushed out to the storage chamber C. Oil hole 17 and compression side damping force generation valve 1
The compression side damping force is generated by the flow resistance of the hydraulic oil passing through 8.

On the other hand, during the extension stroke in which the inner tube 6 comes out of the outer tube 2, the working oil in the storage chamber C is sucked into the oil chamber A through the oil hole 17, and the oil chamber B is also sucked.
The hydraulic oil therein is pushed out from the orifice 19 provided in the center rod 7 to the storage chamber C side, and at this time, the expansion side damping force is generated by the flow resistance of the hydraulic oil passing through the orifice 19.

However, during the compression and extension strokes of the front fork 1 described above, if the frictional resistance between the outer tube 2 and the inner tube 6 that are in sliding contact with each other is large and smooth expansion and contraction operation cannot be performed, this frictional resistance will be the compression side. And, the extension side damping force is affected and the respective damping force characteristics are disturbed.

Therefore, in order to prevent the influence of the frictional resistance as much as possible, in this embodiment, as shown in the detailed view of FIG. 2, the oil chamber A is inserted from the groove 20 provided in the piston 11 to the inner tube 6. An oil hole 21 formed in the outer tube 2 communicates with a portion between the bearings 3 and 4 between the outer tube 2 and the inner tube 6.

Therefore, during the compression stroke of the front fork 1, a part of the hydraulic oil pushed out from the oil chamber A is pushed between the outer tube 2 and the inner tube 6 through the groove 20 and the oil hole 21, The hydraulic oil lubricates the bearings 3 and 4 to ensure a smooth expansion and contraction operation of the front fork 1.

Therefore, the smooth operation of the outer tube 1 and the inner tube 6 is always ensured, and the stable damping force characteristic of the front fork 1 is guaranteed.

Returning to FIG. 1 again, the suspension spring 8 interposed between the inner tube 6 and the center rod 7.
The lower end is supported by the upper end surface of the expanded diameter portion 7a of the center rod 7, and the upper end is supported by the cap 22 that closes the upper end of the inner tube 6 via the spring receiver 23.

In the above case, in the case of FIG. 1 in which the front fork 1 is assembled for an off-road vehicle, a spacer 24 is incorporated between the cap 22 and the spring receiver 23.

As a result, the dimension between the enlarged diameter portion 7a of the center rod 7 provided on the outer tube 2 side and the cap 22 of the inner tube 6 is "the dimension = length of suspension spring 8 + height of spacer 24". Outer tube 2
The supporting height of the inner tube 6 with respect to the height of the suspension spring 8 is increased by the height of the spacer 24, and the inner tube 6 is pulled out from the outer tube 2 and the vehicle height is increased.

Further, when the front fork 1 is fully extended, the outer tube 2 side portion where the piston 11 on the inner tube 6 abuts via the buffer spring 14 becomes the enlarged diameter portion 7a of the center rod 7, and The effective stroke of the fork 1 is also the longest.

Further, at the same time, the expansion side damping force generating orifice 19 on the side of the center rod 7 is fully opened, so that the expansion side damping force characteristic is kept low correspondingly.

On the other hand, when the front fork 1 is assembled for an on-road vehicle, as shown in FIG. 3, instead of incorporating the spacer 24 on the suspension spring 8 side, the spacer 24 is in contact with the lower surface of the expanded diameter portion 7a. It is installed on the outer peripheral surface side of the center rod 7.

As a result, the dimension between the enlarged diameter portion 7a of the center rod 7 provided on the outer tube 2 side and the cap 21 of the inner tube 6 is determined by the length of the suspension spring 8, and the assembly for the off-road vehicle is carried out. Compared with the case of (2), the inner tube 6 is inserted into the outer tube 2 by the height of the spacer 24, and the vehicle height is lowered.

In addition, along with that, the front fork 1
The outer tube 2 side portion where the piston 11 on the inner tube 6 side abuts via the buffer spring 14 at the time of maximum extension of the inner tube 6 is lowered from the expanded diameter portion 7a of the center rod 7 by the height of the spacer 24, and the front fork is correspondingly moved. The effective stroke of 1 is also shortened.

Moreover, at the same time, a part of the expansion side damping force generating orifice 19 on the center rod 7 side is blocked by the spacer 24, so that the expansion side damping force characteristic is adjusted to a high state correspondingly.

Thus, the vehicle height is adjusted corresponding to the assembling for the off-road vehicle shown in FIG. 1 and for the on-road vehicle shown in FIG.
The effective stroke and the damping force characteristic of are also changed, and the damping force characteristic and the extension impact absorbing capacity in each case are appropriately maintained.

Although only one spacer 24 having a predetermined height may be used, if the spacer 24 is divided into a plurality (three in the embodiment) as shown in the embodiment. By appropriately arranging them in the suspension spring 8 side and the center rod 7 side, the effective stroke and the damping force characteristics can be adjusted in multiple stages along with the height of the vehicle body.

If the heights of the divided spacers 24 are individually changed, finer adjustment can be performed by combining them.

Thus, it is possible not only to select between the off-road vehicle and the on-road vehicle, but also to carry out assembly suitable for other vehicle types, differences in vehicle body weight, and the like.

[0049]

As described above, according to the first aspect of the invention, the vehicle height can be adjusted by simply selecting the mounting position of the spacer in the assembling work.
It becomes possible to assemble it for off-road vehicles and on-road vehicles using a front fork made of the same components.

In addition, the effective stroke and damping force characteristic of the front fork are automatically changed in response to the vehicle height adjusting operation, and appropriate damping force characteristic and extension impact absorbing capacity are obtained in accordance with the amount of change. You can

According to the second aspect of the invention, in addition to the above effects, there is an advantage that the effective height and the damping force characteristic can be adjusted in multiple stages in accordance with the height of the vehicle body.

Further, according to the invention of claim 3, in addition to the above-mentioned effect, finer adjustment can be performed only by changing the combination of the spacers. Therefore, the front forks having the same structure are adapted to each vehicle type. As a result, mass production is possible, and there is an advantage that the cost can be remarkably reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a front fork for a motorcycle according to the present invention, which is assembled for an off-road vehicle, by half-cutting.

FIG. 2 is a partial vertical cross-sectional view showing, on an enlarged scale, only a main part of the same.

FIG. 3 is a half-cut longitudinal sectional view showing a state where the front fork for a motorcycle is assembled for an on-road vehicle.

[Explanation of symbols]

 1 Front Fork 2 Outer Tube 6 Inner Tube 7 Center Rod 7a Expanding Portion 8 Suspension Spring 19 Damping Force Generation Orifice 24 Spacer

Claims (3)

[Claims] 1. A spacer which can be fitted to the outer peripheral surface of a center rod extending from the outer tube along the axis and which can be arranged in series between a suspension spring and a supporting portion of the suspension spring, By selectively moving the spacer between the center rod side and the suspension spring side, both the support position of the suspension spring and the maximum extension position of the inner tube can be adjusted, and the spacer is moved to the center rod side. Accordingly, the vehicle height adjusting device for a front fork for a motorcycle, characterized in that the opening area of the damping force generating orifice provided in the center rod is controlled by the spacer. 2. The vehicle height adjusting device for a front fork for a motorcycle according to claim 1, wherein the spacer comprises a plurality of spacers arranged in series. 3. The vehicle height adjusting device for a front fork for a motorcycle according to claim 2, wherein the plurality of spacers are formed of spacers having different heights.