JP2002195332A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb the vibration of a vehicle on a road surface by generating a specified damping force which optimally realize a front fork. SOLUTION: In the front fork, a body side member 1 is joined retractably to an axle side member 2 through a suspension spring 3 installed therebetween, a piston body 13 comes into slidable contact with a cylinder body 11 through a seal ring 13a installed on the outer periphery of the piston body 13 in a damper 10 disposed at a core part, and a rod body 12 comes into slidable contact with an opening end part 11a through a bush 11b fitted onto the opening end part (11a) inner periphery of the cylinder body 11. The rod body 12 is inserted into a tubular guide part 14 continuously fitted to the opening end part 11a of the cylinder body 11 forming the damper 10. The tubular guide part 14 comprises a bush 14a inserted into the inner periphery thereof and coming into slidable contact with the outer periphery of the rod body 12. The rod body 12 is slidably supported by a bush 11a fitted to the opening end part 11a of the cylinder body 114 and a bush 14a fitted to the inner periphery of the tubular guide part 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber, and more particularly to an improvement in a cylindrical hydraulic shock absorber such as a front fork or a shock absorber.

[0002]

2. Description of the Related Art As is well known, a cylindrical hydraulic shock absorber, such as a front fork mounted on a motorcycle or a shock absorber mounted on a four-wheeled vehicle, is used when a road surface vibration is input. It says that it generates damping force while expanding and contracting to absorb the road surface vibration.

[0003] Apart from the shock absorbers, there is a front fork having a built-in damper so that the vibration of the road surface is absorbed by the operation of the damper.

For example, a front fork shown in FIG. 2 has an axle as an axle-side member whose lower end is connected to an axle side of a motorcycle with respect to a body-side tube 1 which is a body-side member whose upper end is connected to a handlebar side of the motorcycle. The side tube 2 is connected to a state in which the side tube 2 is inserted under the presence of the suspension spring 3 so as to be able to protrude and retract.

[0005] The front fork has a damper 10 at its shaft core.
Is a cylinder body 11 provided upright and fixed to the shaft core of the axle-side tube 2, and a cylinder body 11 provided vertically suspended in a fixed state to the shaft core of the vehicle body-side tube 1 and has a lower end in the figure. A rod body 12 having a distal end side which is inserted into the cylinder body 11 so as to be able to protrude and retract into the cylinder body 11, and a rod body 12 which is slidably housed in the cylinder body 11 and is connected to a distal end which is a lower end in the drawing of the rod body 12. And a piston body 13.

On the other hand, the damper 10 has, for example, an extension-side damping valve (not shown) in the piston body 13, and when the piston body 13 rises in the cylinder body 11, the extension-side damping valve is provided. It is stated that a predetermined extension side damping force is generated by the damping valve.

Therefore, in this damper 10,
Under the state where the axis of the cylinder body 11 and the axis of the rod body 12 coincide with each other, the cylinder body expands and contracts by an external force input along the axis to generate a predetermined damping force, that is, enables vibration absorption. Will be.

For this reason, in the front fork shown in the drawing, aside from the structure in which the axle-side tube 2 protrudes and retracts from the vehicle-body-side tube 1, in the damper 10, the rod body 12 has an upper end head portion which is an opening end of the cylinder body 11. Bush 11 fitted on the inner circumference at 11a
b and a seal ring 13 a interposed on the outer periphery of the piston body 13.

Incidentally, the seal ring 13a provided on the outer periphery of the piston body 13 has an oil sealing function and a bearing function, and is often formed of an appropriate resin material.

Therefore, according to this front fork, the bush 11b disposed on the upper end head portion 11a of the damper 10 and the seal ring 13a interposed on the outer periphery of the piston 13 form the connection between the cylinder 11 and the rod 12. Axiality between them, that is, a state where the axial lines of the cylinder body 11 and the rod body 12 coincide with each other, is ensured. This axialness is also ensured between the vehicle body side tube 1 and the axle side tube 2. , A smooth expansion and contraction operation can be realized.

In addition to the so-called normal running of the motorcycle on which the front fork is mounted, so-called normal running can be absorbed, as well as the road surface vibration inputted when running on a bad road.

[0012]

However, when observing the situation where the front fork is mounted on the motorcycle, the upper end is connected to the steering wheel side and the lower end is connected to the axle side of the front wheel. It is mounted on a motorcycle at an angle.

As a result, the same applies between the body-side tube 1 and the axle-side tube 2 by repeating the landing of the motorcycle after traveling on a rough road or, in some cases, after jumping. The axial center line is no longer aligned with the rod body 12, and the bush 11 b in the upper end head portion 11 a and the seal ring 13 a interposed between the piston body 13 are arranged in a horizontal direction, that is, an axial core line which is a direction in which the hydraulic shock absorber expands and contracts. An external force in a direction orthogonal to the direction acts.

Therefore, particularly, the seal ring 13a made of a resin material is easily deformed, and since the seal ring 13a has a bearing function at the portion of the piston body 13 having a large diameter, the contact area becomes large and sliding occurs. The resistance is increased, the sealing property and the sliding property are reduced, and it becomes impossible to generate a predetermined damping force.

The present invention has been made in view of the above circumstances, and has as its object to enable generation of damping force as set and to absorb road surface vibrations in a vehicle, for example, a motorcycle. An object of the present invention is to provide a hydraulic shock absorber that is optimal for being embodied as a front fork mounted on a vehicle.

[0016]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention basically relates to a vehicle-side member whose upper end is connected to the vehicle body of the vehicle and whose lower end is connected to the axle of the vehicle. A cylinder body in which the connected axle-side member is connected to the suspension core so as to be able to protrude and retract under the arrangement of the suspension spring, while the damper arranged in the axle part is fixed to the axle part of the axle-side member. A rod body fixed to the shaft core of the vehicle body side member and inserted through the cylinder so as to be able to protrude and retract, and a piston body slidably housed in the cylinder body and connected to the rod body In the damper, the piston body is in sliding contact with the cylinder body via a seal ring interposed on the outer circumference, and the rod body is connected via a bush fitted on the inner circumference at the open end of the cylinder body. Do not slide in contact with this open end In a hydraulic shock absorber, a rod body is inserted inside a cylindrical guide part connected to an open end of a cylinder body constituting a damper, and the cylindrical guide part is fitted on an inner periphery. And a bush that slides on the outer periphery of the rod body. The rod body is slidably supported by the bush fitted on the open end of the cylinder body and the bush fitted on the inner circumference of the cylindrical guide. Let's say

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on the illustrated embodiment. Even a front fork as a hydraulic shock absorber according to the present invention is basically shown in FIG. It has the same configuration as that of the conventional front fork.

Therefore, in the following description, portions having the same configuration as that of the conventional front fork will be denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted unless necessary. I do.

Incidentally, as is the case with the above-mentioned conventional front fork, as shown in the figure, the front fork uses the vehicle body tube 1 as the upper end member and the axle tube 2 as the lower end member. It is assumed that the inner tube is set to a so-called inverted type. At this time, the damper 10 is set to a so-called upright type.

A cylindrical spacer 4 is formed concentrically on the shaft core on the upper end side of the vehicle body side tube 1, and the upper end of the suspension spring 3 is engaged with the lower end of the spacer 4. .

The lower end of the suspension spring 3 is carried on the upper end of an upper end head 11a, which is an open end of the cylinder body 11 constituting the damper 10.

The upper end of a rod 12 whose upper end is connected to the upper end of the vehicle body side tube 1 and constitutes a damper 10 is inserted through the inner shaft core of the spacer 4.

Based on the above assumptions, in the front fork shown in the drawing, a rod body 12 which is connected to the upper end head portion 11a of the cylinder body 11 forming the damper 10 and also forms the damper 10 inside is formed. It has a cylindrical guide portion 14 to be inserted.

In this front fork, it is assumed that the cylindrical guide portion 14 has a bush 14a fitted on the inner periphery thereof. The bush 14a has a rod inserted through the inside of the cylindrical guide portion 14. The outer periphery of the body 12 is slid.

At this time, the cylindrical guide portion 14 is shown as being integrally connected to the upper end head portion 11a, that is, extending from the upper end head portion 11a, as shown in the drawing. In view of the function of the guide portion 14, it is not always necessary to be integrally connected to the upper end head portion 11a. For example, the cylindrical guide portion 14 formed separately by sintering or press molding is used as the upper end head. Needless to say, the portion 11a may be continuously connected to the portion 11a in a fixed state by appropriate means.

In particular, when the cylindrical guide portion 14 is formed separately from the damper 10, it is possible to prevent a significant change in the design of the cylinder body 11 constituting the damper 10. This is advantageous.

Since the tubular guide portion 14 is assumed to be present inside the suspension spring 3 as shown in the figure, the tubular guide portion 14 is connected to the upper end head portion 11a. Is designed so that a space for supporting the lower end of the suspension spring 3 is secured at the upper end of the upper end head portion 11a.
The outer diameter of the suspension spring 3 is set so as to guide the inner periphery of the suspension spring 3, not to mention a dimension that does not hinder the expansion and contraction operation of the suspension spring 3. It is also possible to fulfill the function of preventing buckling.

The rod 12 is inserted through the inside of the cylindrical guide portion 14.
It is important that no sliding resistance is generated between the cylindrical guide portion 14 and the cylindrical guide portion 14.

Therefore, although not shown in detail, between the inner periphery of the cylindrical guide portion 14 and the outer periphery of the rod body 12,
It is stated that a gap that allows the flow of oil is formed with an interval larger than the sliding gap.

At this time, in order to avoid the oil sealing phenomenon in the gap, it is preferable to form a through hole 14b for communicating the gap with the outside in the cylindrical guide portion 14.

Therefore, in this damper 10,
The rod body 12 is supported by the bush 11b fitted on the inner periphery of the upper end head portion 11a of the cylinder body 11 and the bush 14a fitted on the inner periphery of the cylindrical guide portion 14.

As a result, the cylinder body 11 and the rod body 12
In this case, the rod body 12 having a small diameter is supported at two points in the axial direction, and the bush 11b of the upper end head portion 11a of the cylinder body 11 in the case of the conventional front fork shown in FIG. And the seal ring 1 of the piston body 13 having a larger diameter than the rod body 12
Compared to the case where the piston body 13 is supported, since no lateral external force acts on the sliding portion of the piston body 13, the sliding resistance is small and the operability is improved.
It is possible to interpose a seal ring 13a having only a sealing function.

When the damper 10 is supported at two locations in the axial direction, since the so-called second support location is on the rod 12 side, the damper 10 is supported at two locations in this manner. For example, Japanese Patent No. 196958
As compared with the proposal disclosed in Japanese Patent Application Laid-Open Publication No. H10-115, the distance between adjacent bushes can be increased, and effective two-point support can be realized.

That is, the above-mentioned patent publication discloses that the valve stopper in the piston portion housed in the cylinder is expanded in diameter, and the outer periphery thereof is connected to the inner periphery of the cylinder via a bush interposed there. Although it is a proposal to provide a second support point so as to make sliding contact, in this case, the second support point is close to the seal ring in the piston part, and depending on the viewpoint, The positional relationship is such that it can be identified with the seal ring in the piston portion.

Therefore, in view of this, the proposal disclosed in the above-mentioned publication shows a form of two-point support in appearance, but from a practical point of view, an effective two-point support is provided. Therefore, it can be said that it is still supported at one place.

In the proposal disclosed in the above-mentioned publication, a bush having the same diameter as the seal ring comes into sliding contact with the inner periphery of the cylinder.
In the case of the present invention, since the bush 14a having the same diameter as the rod body 12 having a smaller diameter slides on the outer periphery of the rod body 12, it is advantageous in that the sliding resistance does not increase unnecessarily.

In addition, in the proposal disclosed in the above-mentioned publication, the bush is interposed on the outer periphery of the valve stopper, so that the valve stopper has a sufficient thickness for interposing the bush. As a result, there is a disadvantage that the length of the piston portion in the axial direction is increased and the effective stroke that the piston portion can slide in the cylinder is reduced. Since no point is provided, it is advantageous not to reduce the effective stroke described above.

Even if the front fork having the damper 10 formed as described above expands and contracts in a state where the front fork is installed in an oblique state in a two-wheeled vehicle,
Even if the motorcycle runs on rough roads or repeats landing after jumping in some cases, the axis of the cylinder does not bend between the cylinder body 11 and the rod body 12 in the damper 10. The shaft center line between the axle side tube 2 and the axle side tube 2 is no longer bent,
The damper 10 can smoothly expand and contract without exhibiting a galling phenomenon, and can generate a damping force as set without impairing the sealing performance induced by the galling phenomenon.

In the above description, the case where the front fork is configured as a so-called inverted type in which the body-side tube 1 as the upper end member is the outer tube and the axle tube 2 as the lower end member is the inner tube has been described. Instead of this, from the point of view of the present invention, although not shown, the vehicle body side tube 1 as the upper end side member of the front fork is an inner tube, and the axle side tube 2 as the lower end side member is an outer tube. The damper 10 may be set to a so-called upright type. In this case, the damper 10 may be set to a so-called inverted type instead of being set to a so-called upright type. In any case, the operation and effect do not differ.

Incidentally, when the damper 10 is set upside down, the cylinder 11 is raised and the rod 12
When the oil lock function is exhibited when the oil lock piece is fitted to an oil lock case provided at the lower end of the rod body 12, the tubular guide portion 14 is regarded as an oil lock piece. It is also possible to do.

In the above description, the case in which the cylindrical hydraulic shock absorber is a front fork mounted on a motorcycle is taken as an example. However, it is needless to say that the present invention can be embodied in a shock absorber that is the same cylindrical hydraulic shock absorber, and the operation and effect in that case are not basically different.

[0042]

As described above, according to the present invention, the bush in which the damper is fitted on the inner periphery of the opening end of the cylinder body and the bush in which the damper is fitted on the inner periphery of the cylindrical guide portion. Will support the rod body.

As a result, between the cylinder body and the rod body, a so-called small-diameter rod body is supported at two locations in the axial direction. Compared to a case where a large piston body is supported with an interposed seal ring,
Since no lateral external force acts on the sliding part of the piston body, the sliding resistance is small and the operability is improved. In the piston body, a seal ring having only a sealing function can be interposed. become.

Therefore, it is difficult for the shaft core to be bent in the damper and the hydraulic shock absorber, so that the galling phenomenon caused by the bending of the shaft core is not exhibited.
There is no fear that the sealing property and the slidability are reduced, and the stretchability as set can be ensured, and the generation of the damping force as set can be expected.

In the present invention, since the rod body side is used when two places are supported, for example, in the proposal disclosed in Japanese Patent No. 196958, This is advantageous in that the sliding resistance does not increase unnecessarily as compared with the case where a bush having the same diameter as the seal ring slides on the inner periphery of the cylinder.

Further, according to the proposal disclosed in the above-mentioned publication, the bush is interposed on the outer periphery of the valve stopper, so that the valve stopper has a sufficient thickness to allow the bush to be interposed. As a result, there is a disadvantage in that the length of the piston portion in the axial direction is increased and the effective stroke in which the piston portion can slide in the cylinder is reduced. However, according to the present invention, since no supporting portion is provided in the damper, This is advantageous in that the effective stroke is not reduced.

As a result, according to the hydraulic shock absorber of the present invention, it is possible to generate a damping force as set, and to absorb road surface vibrations in a vehicle, for example, it is optimally embodied as a front fork.

[Brief description of the drawings]

FIG. 1 is a schematic elevational view showing a front fork according to the present invention, partially cut away.

FIG. 2 is a diagram showing a front fork as a conventional example, similarly to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body side tube which is a vehicle side member 2 Axle side tube which is an axle side member 3 Suspension spring 4 Spacer 10 Damper 11 Cylinder body 11a Upper end head part which is an opening end part 11b, 14a Bush 12 Rod body 13 Piston body 13a Seal ring 14 Cylindrical shape Guide part 14b Through hole

Claims (1)

[Claims] 1. A vehicle-body-side member having an upper end connected to a vehicle-body side of a vehicle and an axle-side member having a lower end connected to an axle-side of the vehicle are connected so as to be able to protrude and retract under a suspension spring. A damper disposed on the shaft core portion is fixedly disposed on the shaft core portion of the axle-side member, and a damper disposed on the shaft core portion of the vehicle body-side member so as to be inserted and retracted into and out of the cylinder body. And a piston body slidably housed in the cylinder body and connected to the rod body, and the piston body of the damper is provided with a cylinder body via a seal ring interposed on the outer periphery. And a rod body slidingly contacts the opening end of the cylinder body via a bush fitted on the inner periphery of the opening end of the cylinder body, wherein the rod body constitutes a damper. Open end in body And a bush which is inserted into the inside of a cylindrical guide portion provided continuously with the cylinder body, and which has a bush which is fitted on the inner periphery and slidably contacts the outer periphery of the rod body. A hydraulic shock absorber characterized in that it is supported by being slidably contacted with a bush fitted to the opening end of the opening and a bush fitted to the inner periphery of the cylindrical guide portion.