JPS6235128A - Air vent structure for shock absorber stopper - Google Patents

Abstract

PURPOSE:To enable secure shock absorption by making at least either of opposing surfaces of a cylindrical stopper consisting of synthetic resins and the like and a shock absorber in an irregular form and providing an air vent part so as to prevent the increase in the spring constant of the stopper. CONSTITUTION:On the outer circumference at the upper end part of a piston rod 12, a stopper 30 of a cylindrical shape consisting of synthetic resins such as foam polyurethane is fitted. On the bottom surface of this stopper 30, the plural number of projections 40 is provided, and when the stopper 30 comes in contact with the contact plate 42 being fitted on the upper end of a shock absorber body 10, the air around the inner circumference of the stopper 30 is released to the exterior so as to prevent the increase in the spring constant of the stopper 30. Further, even if irregularity is provided on the contact plate 42 instead of the projections 40 of the stopper 30, similar action or effect can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air bleed structure for a shock absorber stopper used in a suspension device of an automobile or the like.

[Foreground technology]

In an automobile suspension device, a piston rod protruding from a shock absorber body expands and contracts with the shock absorber body and moves relative to the shock absorber body, thereby attenuating vibrations due to fluid resistance within the shock absorber body.

A cylindrical stopper is attached to the piston rod near its tip, and is used for contact with the shock absorber body during large vibrations.

This stopper is configured such that when the shock absorber main body moves significantly, the end portion of the shock absorber main body comes into contact with one axial end, thereby being compressed in the axial direction, thereby limiting the amount of movement of the shock absorber main body.

For this reason, the axial end of the stopper is closed by the shock absorber body, and when compressed, the internal pressure increases, the spring constant increases, and the movement of the shock absorber body may be abruptly stopped.

For this reason, conventionally, it has been considered to partially increase the inner diameter of the axial end opposite to the shock absorber main body to provide an air vent between the shock absorber and the outer periphery of the piston rod. According to this configuration, even when the motorcycle absorber body comes into contact with the stopper, the air inside the stopper is discharged through the air vent, so that the spring constant of the stopper does not increase.

However, increasing the inner diameter of the stopper has the problem that the stopper cannot be attached to the piston rod sufficiently.

The present invention has been made in consideration of the above-mentioned facts, and an object of the present invention is to provide an air bleed structure for a shock absorber stopper that can securely mount the stopper and ensure air bleed during overstroke.

[Summary and operation of the invention]

The air bleed structure for a shock absorber stopper according to the present invention is used in a shock absorber that absorbs impact by relative movement between the shock absorber body and the rod,
The shock absorber is characterized in that at least one of the facing surfaces of the shock absorber and the cylindrical stopper, which is brought into contact with the shock absorber main body when the shock absorber body moves by a predetermined amount or more, is formed into an uneven shape to serve as an air bleed portion.

Therefore, in the present invention, the stopper can be reliably attached to the piston rod, and when the shock absorber body overstrokes, an air bleed part is secured between the shock absorber body and the stopper, and the spring constant of the stopper is reduced. Preventing it from increasing.

[Embodiments of the invention]

FIG. 1 shows the vicinity of the upper part of a suspension device to which a first embodiment of the present invention is applied.

This suspension device includes a cylindrical shock absorber body 10 with a vertical axis, a heavy stone rod 1
2 is inserted into the shock absorber body 10, and a piston (not shown) is attached to the lower end of the piston rod 12 within the shock absorber body 10.

A through hole is bored in this piston, and when the piston moves, the liquid sealed in the shock absorber body 10 flows through this through hole, so that vibrations are damped by its viscous resistance. It has become. Vibration is transmitted from the wheels of the automobile to the lower end of the shock absorber main body IO.

A small diameter bolt 16 coaxially protrudes from the upper end of the piston rod 12.
8. Spacer 20 and upper receiving plate 22 are inserted. The outer diameter of the washer 18 is larger than the outer diameter of the piston rod 12.

Note that these washers 18, spacers 20 and bolts 1
6 may have a structure in which these are integrally formed and this integral body is fixed to the upper end portion of the piston rod 12 by a suitable fitting structure, welding, or the like.

Bolts 16 and nuts 24 are tightened from above the upper receiving plate 22 to fix the upper receiving plate 22 to the shock absorber body 10. Note that a portion of the upper receiving plate 22 is connected to the vehicle body, so that it can support the load from the wheels. Further, this upper receiving plate 22 corresponds to a lower receiving plate 26 fixed to the outer periphery of the shock absorber main body 10.
A compression coil spring 28 is interposed between the lower support plate 26 and the lower support plate 26 . As a result, the piston rod 12 is subjected to an urging force in a direction to be pulled out from the shock absorber main body 10.

A stopper 30 attached to the outer periphery of the piston rod 12
It has a cylindrical shape and is made of synthetic resin such as polyurethane foam.

Piston rod 12 passing through the axis of this stopper 30
The insertion hole 32 has a small diameter portion 34 at its upper end, and a large diameter portion 36 is formed below the small diameter portion 34.

The boundary between the small diameter portion 34 and the large diameter portion 36 is a stepped portion 38, and the stopper 30 is prevented from falling off by abutting the circumference of the washer 18 with this stepped portion 38.

As shown in FIG. 2, a plurality of protrusions 40 (six in this embodiment) protrude toward the shock absorber body 10 at the lower end of the stopper 30. The protrusions 40 in this embodiment are hemispherical, and the space between them is an air vent.

Next, the operation of this embodiment will be explained.

In order to attach the stopper 30 to the piston rod 12, it is sufficient to attach the washer 18 and the spacer 20 to the piston rod 12 in advance, and then cap the large diameter portion 36 of the stopper 30 onto the piston rod 12 from above, that is, from the direction of the bolt 16. . As a result, the small diameter portion 34 and the large diameter portion 36
The stepped portion between the two contacts the washer 18 and the insertion is stopped.

After that, the upper receiving plate 22 is attached onto the spacer 20 and the nut 24 is tightened to complete the assembly. Since the small diameter portion 34 of the stopper 30 is locked to the washer I8, the stopper 30 will not fall off from the piston rod 12. . Particularly, since the small diameter portion 34 of the insertion hole 32 is in close contact with or close to the outer periphery of the spacer 20, installation is difficult.

Place the tightening washer 18 and spacer 20 on the stopper 3.
0, and this subassembly part may be attached to the piston rod 12.

In the suspension device assembled in this manner, vibrations generated as the vehicle travels are attenuated and absorbed by the relative movement in the axial direction between the stopper 30 and the piston rod 12.

If this vibration is large, the Nova main body 10 moves upward in FIG. 1 more than necessary and comes into contact with the lower end of the stopper 30. Therefore, the stopper 30 is compressed, and its elasticity causes the shock absorber main body 10 to
absorbs the shock of

Further, since the stopper 30 of this embodiment is provided with a protrusion 40 at the lower end, even if the shock absorber main body 10 comes into contact with the stopper 30, the air bleed portion between the protrusions 40
Since the inside and outside of the stopper 30 are communicated with each other, the air pressure inside the stopper 30 does not increase. Therefore, the spring constant of the stopper 30 does not increase even when the shock absorber main body 10 comes into contact with the shock absorber body 10, and reliable shock absorption is possible.

In this way, the protrusion 40 of the stopper 30 qualitatively reduces the cross-sectional area of the lower end of the stopper 30, so
This also has the effect of making the initial load characteristics in contact with the shock absorber body 10 more flexible.

FIG. 3 shows a second embodiment of the invention.

In this embodiment, the air bleed part is not provided at the lower end of the stopper 30 as in the previous embodiment, but is formed on the abutment plate 42 disposed at the upper end of the shock absorber body 10.

That is, the abutment plate 42 has a disc shape, and has concave portions 44 formed at a plurality of locations on the circumference to form an uneven shape. This recess 44 extends in the radial direction, and even when the lower end of the stopper 30 contacts the contact plate 42, a gap is formed between the lower end of the stopper 30 and the air vent. The structure is such that the inside and outside of the stopper 30 are communicated through the stopper 30.

Therefore, also in this embodiment, when the shock absorber main body 10 comes into contact with the stopper 30, an air bleed portion can be reliably secured.

〔Effect of the invention〕

As explained above, the air bleed structure according to the present invention is used in a shock absorber that absorbs shock by the relative movement between the shock absorber body and the piston rod, and when the shock absorber body and the piston rod move relative to each other by a predetermined amount or more, the air bleed structure comes into contact with the shock absorber body. At least one of the facing surfaces of the cylindrical stopper and the shock absorber is unevenly shaped to serve as an air bleed part, so that the stopper can be installed securely, and
Moreover, it has an excellent effect without increasing the spring constant during overstroke.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing a first embodiment of the air vent structure for a shock absorber stopper according to the present invention, and FIG.
FIG. 3 is a cross-sectional view taken along the line I--I, and FIG. 3 is a perspective view showing the upper end of the shock absorber main body according to the second embodiment. DESCRIPTION OF SYMBOLS 10... Shock absorber main body, 12... Piston rod, 30... Stopper, 40... Protrusion, 42... Contact plate.

Claims (1)

[Claims] Used in shock absorbers that absorb shock through relative movement between the shock absorber body and piston rod.
An air bleed for a shock absorber stopper, characterized in that at least one of the facing surfaces of the shock absorber and the cylindrical stopper that comes into contact with the shock absorber main body when the shock absorber body is moved by a predetermined amount or more relative movement is formed into an uneven shape to serve as an air bleed part. structure.