JP2003329075A - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front fork applicable to both erecting and inverting types, wherein a weight of an outer tube is not increased even if a rigidity in a fore-and-aft direction of the front fork is increased so as to be downsized, and both material saving and cost reduction are achieved. <P>SOLUTION: In the front fork where the outer tube 2 is slidably inserted in the outer circumference of an inner tube 1 through a bearing 3, the outer and inner tubes are constituted into a cylinder shape. Inner circumferential walls of both sides of the outer tube are cut off along an axial direction to form thin walls, and an oil sump 11 is formed between the inner circumferences 8 of both the sides and the outer circumference of the inner tube. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork which is interposed between a vehicle body and a wheel of a motorcycle and serves as a fork and a shock absorber.

[0002]

2. Description of the Related Art As this type of front fork, for example, as shown in FIGS. 3A and 3B, an inverted front fork and an upright front fork are known.
In the inverted front fork, the axle side inner tube 1 is slidably inserted into the vehicle body side outer tube 2, and in the upright type front fork, the vehicle body side inner tube 1A is slidable in the axle side outer tube 2A. Has been inserted into.

The inverted front fork is shown in FIG.
As shown in FIG. 1, the vehicle body side outer tube 2 is slidably inserted into the outer circumference of the axle side inner tube 1 via the bearing 3 on the base end side, and the damper cylinder 4 stands upright in the center of the inner tube 1 and A piston rod 5 slidably inserted into the cylinder 4 via a piston is coupled to the upper portion of the outer tube 2.

A suspension spring 7 is interposed between the upper end seat portion 6 of the damper cylinder 4 and the upper end of the outer tube 2 to constantly urge the outer tube 2 and the piston rod 5 in the extending direction.

A gap 8 is formed between the inner circumference of the outer tube 2 and the outer circumference of the inner tube 1.
Is communicated with an oil chamber 10 in the inner tube 1 through an oil hole 9 formed in the inner tube 1 to supply lubricating oil.

[0006]

In the conventional front fork, the riding comfort is affected by the rigidity and softness of the outer tube 2 and the inner tube 1.

As shown in FIGS. 3A and 3B, the front fork is mounted so as to be inclined forward with respect to the vehicle body, and as a result, vibrations and the like are input upward from the road surface through the wheels. Therefore, the strength of the front fork needs to be increased in the front-rear directions a and b as compared with the left-right direction.

For this reason, conventionally, when changing the rigidity of the front fork, it is general to change the outer diameter of the outer tube 2 so as to match the strength in the front-rear directions a and b.

In this case, for example, when the outer diameter of the outer tube 2 is increased to be thicker so as to match the strength in the front-rear directions a and b, the weight of the outer tube 2 increases and the material becomes bulky. However, there is a problem that increases the cost.

Therefore, for example, in an upright front fork as shown in FIG. 3 (B), an outer tube 2A having an oval cross section has been developed by increasing only the wall thickness in the front-rear direction a, b. ing.

However, if the outer tube 2 of the inverted front fork as shown in FIG. 3 (A) is also made into an elliptical shape, the hole for fitting and fixing the outer tube 2 of the bracket B also needs to be formed into an elliptical shape. On the contrary, the workability is inferior and the cost is increased.

Therefore, the object of the present invention is to reduce the weight of the outer tube without increasing the rigidity of the front fork in the front-rear direction, and it is applicable to both the upright type and the inverted type. It is to provide a front fork that can achieve both material saving and cost reduction.

[0013]

In order to achieve the above-mentioned object, the means of the present invention is a front fork in which an outer tube is slidably inserted into the outer circumference of an inner tube through a bearing, The outer tube and the inner tube are configured in a cylindrical shape, and the inner peripheral wall portions on both sides of the outer tube are cut along the axial direction to form a thin wall,
It is characterized in that an oil reservoir is formed between the inner circumference of the both side portions and the outer circumference of the inner tube.

In this case, it is preferable that an oil hole is formed in the inner tube, and the oil in the inner tube is supplied to the gap as the lubricating oil through the oil hole.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In a front fork according to the present invention, as shown in FIGS. 1 and 2, an outer tube 2 on the vehicle body side is slidable on an outer circumference of an inner tube 1 on a wheel side via a bearing 3 on a base end side. Has been inserted into.

Incidentally, although the front fork is of an inverted type in the drawing, in the embodiment of the present invention, the front fork is of an upright type, although not shown, instead. good.

A damper cylinder 4 is erected at the center of the inner tube 1, and a piston rod 5 slidably inserted into the damper cylinder 4 via a piston is connected to the upper portion of the outer tube 2 so as to interlock with each other. Has become.

A suspension spring 7 is interposed between the upper end seat portion 6 of the damper cylinder 4 and the upper end of the outer tube 2 to constantly urge the outer tube 2 and the piston rod 5 in the extending direction.

Further, in the front fork of the present invention, the outer tube 2 and the inner tube 1 are formed in a cylindrical shape such that the outer shapes of the outer tube 2 and the inner tube 1 are circular.

In particular, as shown in FIG. 2, the outer tube 2 has a wall thickness having a desired rigidity in the front-rear directions a and b, and both side portions c and d which are not required to have the strength in the front-rear direction.
The inner circumference 8 is cut along the axial direction to form a thin wall.

A gap serving as an oil reservoir 11 is formed between the inner circumference of the thin portion 2a and the outer circumference of the inner tube 1.

Further, an oil hole 9 is provided on the upper part of the inner tube 1.
The oil in the oil chamber 10 in the inner tube 1 is supplied to the oil reservoir chamber 11 as lubricating oil through the oil hole 9.

Therefore, according to the present invention, the thicknesses of the thin portions 2a on both sides are reduced while the thickness in the front-rear directions a and b is set to meet the required strength, and therefore the weight can be reduced.

Further, since oil is constantly supplied to the oil reservoir 11, this oil is used as lubricating oil between the outer tube 2 and the inner tube 1 and between the bearing 3 and the outer circumference of the inner tube 1. Therefore, the slidability of the inner tube 1 and the outer tube 2 is improved.

[0025]

The present invention has the following effects.

1) According to the invention of each claim, the thickness of the outer tube in the front-rear direction can be made to be a thickness commensurate with the required strength, and the thickness of both sides can be made thin, thereby reducing the weight of the entire front fork. Can be achieved.

Similarly, since the outer tube has a perfect circular cross section, it can be applied to either an upright type or an inverted type, and the bracket for supporting the front fork on the vehicle body side can be used as usual.

2) According to the invention of claim 2, since oil is constantly supplied to the oil reservoir, this oil is present between the outer tube and the inner tube and between the bearing and the outer circumference of the inner tube. It can be used as lubricating oil and improves the slidability of the inner and outer tubes.

[Brief description of drawings]

FIG. 1 is a partially cutaway vertical front view of a front fork according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view across the line AA of FIG.

FIG. 3A is a schematic side view of a conventional inverted front fork, and FIG. 3B is a schematic side view of a conventional upright front fork.

FIG. 4 is a partially cutaway vertical front view of a conventional front fork.

[Explanation of symbols]

1 inner tube 2 Outer tube 2a Thin part 3 bearings 8 inner circumference 9 oil holes 11 oil reservoir

Claims (2)

[Claims] 1. In a front fork in which an outer tube is slidably fitted on the outer periphery of an inner tube via a bearing, the outer tube and the inner tube are formed in a cylindrical shape, and A front fork characterized in that the inner peripheral wall portion is cut along the axial direction to be formed into a thin wall, and an oil reservoir is formed between the inner periphery of the both side portions and the outer periphery of the inner tube. 2. A front fork characterized in that an oil hole is formed in the inner tube, and the oil in the inner tube is supplied to the oil sump chamber as lubricating oil through the oil hole.