JPS6330832Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber, and more particularly to a hydraulic shock absorber in which a sealing member disposed between a cylinder and a piston is improved.

Generally, the damping force characteristics of a hydraulic shock absorber are determined by the piston speed. Therefore, when a car with a hydraulic shock absorber installed in its suspension is driving straight on a good road and overcomes a small unevenness, if the car's speed exceeds a certain speed, the piston speed is quite high. Hydraulic shock absorbers generate high damping forces, which impair ride comfort. In order to avoid this, if the damping force of the hydraulic shock absorber is lowered overall, the damping force in the region where the piston speed is low during turning will naturally be lower, making it impossible to suppress rolling and being disadvantageous in terms of handling stability. becomes. Also,
It becomes difficult to reduce so-called nose dive, where the front of the vehicle body sinks during braking. Furthermore, even when the piston speed is high when the vehicle is traveling on a rough road, the overall damping force is reduced, and therefore sufficient damping cannot be achieved, impairing ground contact. In short, when a conventional hydraulic shock absorber whose damping force characteristics are determined only by the piston speed is installed in an automobile suspension, there is a limit to the ability to achieve both ride comfort and handling stability.

Next, although it is not directly related to the damping force characteristics of a hydraulic shock absorber, when a hydraulic shock absorber is used as a strut in a strut-type suspension, a lateral force acts on the hydraulic shock absorber, causing a piston is tilted toward the cylinder. As a result, if the piston band attached to the piston is relatively long and elastically contacts the inner peripheral surface of the cylinder, a gap is created between the piston and the piston band, causing liquid leakage. Furthermore, if the piston band is relatively short, the cylinder and piston band will come into contact with each other locally, increasing the surface pressure on the piston band and increasing the frictional force when the piston band slides on the cylinder. Severe wear on the cylinder and/or piston band. As wear progresses, fluid leakage increases, and the function as a hydraulic shock absorber may eventually deteriorate.

Therefore, the purpose of the present invention is to provide a hydraulic shock absorber that achieves both ride comfort and steering stability without generating damping force when the amount of displacement of the piston is small, and that solves the problem when lateral force is applied. Our goal is to provide the following.

The present invention is a hydraulic shock absorber in which a piston is movably disposed within a cylinder, and includes a sealing member disposed between the cylinder and the piston;
The sealing member includes an elastic body fixed to the outer peripheral surface of the piston, and a piston band fixed to the outer peripheral surface of the elastic body and in contact with the inner peripheral surface of the cylinder, and the piston band has a gap in the circumferential direction. They are butted against each other at a distance, and are expandable and contractible in the radial direction.

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

The present invention is a hydraulic shock absorber in which a piston 12 is movably disposed within a cylinder 10, as shown in FIG. 1, and includes a sealing member 14 disposed between the cylinder 10 and the piston 12.

In the illustrated example, the cylinder 10 is a so-called twin inch tube type inner cylinder;
An outer cylinder 16 is disposed at a distance radially outward from the cylinder 10, and the interval 18 serves as a reservoir chamber for the liquid filled into the cylinder 10.

Piston 12 connects the lower end of piston rod 20. The piston 12 has a port 22 through which liquid flows when the piston rod 20 is extended;
It has a port 24 through which liquid flows during contraction.
A valve body 28 biased by a spring 26 is brought into contact with the lower side of the port 22, and constitutes a valve that generates a damping force when the piston rod 20 is extended. Further, a valve body 32 biased by a spring 30 is brought into contact with the upper side of the port 24 . Since the spring force of this spring 30 is small, no damping force is generated by the port 24 and the valve body 32, and the valve body 32 acts as a check valve when the piston rod is extended. A valve (not shown) that generates a damping force when the piston rod is compressed is disposed at the bottom of the inner cylinder 10.

The seal member 14 includes an elastic body 34 and a piston band 36. In the illustrated example, the elastic body 34 integrally includes a cylindrical main body 38 made of rubber and a pair of flange parts 39 extending radially outward from the main body 38. This elastic body 34
is arranged in a groove 40 provided on the outer periphery of the piston 12 and fixed to the outer periphery thereof.

As shown in FIG. 2, the piston band 36 is formed into a cylindrical shape. This piston band is made by bending a plate material such as metal or elastic plastic into a cylinder, and the end face is formed with a gap of 42 mm in the circumferential direction.
and compare them. As a result, the piston band 36 can expand and contract in the radial direction due to its elasticity. When the end surfaces are butted together, it is preferable to form the ends so that the ends 43 and 44 overlap in the axial direction of the cylinder 10, as shown in FIG. A coating 37 with a low friction coefficient is applied to the outer peripheral surface of the piston band 36 to reduce friction.

The piston band 36 is fixed to the outer peripheral surface of the elastic body 34 and is in contact with the inner peripheral surface of the cylinder 10. In the illustrated example, the piston band has an elastic body 34 in the axial direction.
It is sandwiched between the flange portions 39 of. The piston band 36 is fixed by vulcanizing and adhering the piston together with the elastic body 34, or by arranging the piston band 36 at a distance from the piston and press-fitting the elastic body 34.

When the piston rod 20 moves in the retracting direction during use, in the conventional hydraulic shock absorber, the liquid chamber 50 below the piston 12 is pressurized, and the liquid in this liquid chamber passes through the valve provided at the bottom of the cylinder 10. It flows and generates damping force. However, in the present invention, as shown in FIG. 3a, the elastic body 34 is bent and the piston band 36 moves as if it were left behind, so there is no pressure increase in the liquid chamber 50 at the initial stage, that is, at the time of minute displacement. There is almost no damping force. As the displacement increases, the elastic body 34 comes into contact with the step 41 above the groove 40 provided in the piston, and the deflection load increases rapidly, so the piston band 36 begins to move together with the piston 12. The damping force is generated by a valve at the bottom. When the piston rod moves in the direction of extension, the elastic body 3
4 is deflected as shown in FIG. 3b and has a similar effect. Also, when a lateral force is applied during use, the elastic body 34
bends in the radial direction, so no gap is created between the piston band 36 and the cylinder 10.

In the example shown in FIG.
and a piston band 58. In this case, when the axial deflection of the elastic body 56 reaches its limit, the piston band 58
Starts to slide against.

In the example shown in FIG. 5, the piston 12 is provided with a pair of flanges 60 and 61 spaced apart in the axial direction, and a sealing member 66 consisting of an elastic body 62 and a piston band 64 is surrounded by the flanges. ing. When the elastic body 62 is displaced during use and one of the flange portions hits the piston band 64, the elastic body 62 can no longer be displaced and the piston band 64 begins to slide with respect to the cylinder 10.

According to the present invention, the damping force characteristics change according to the displacement of the piston, so when the hydraulic shock absorber according to the present invention is installed in the suspension of an automobile, the riding comfort is improved.
Maneuvering stability and vibration and noise characteristics can be satisfied at the same time. Furthermore, since there is little increase in frictional force when a lateral force is applied, riding comfort can be improved from this point as well. Furthermore, leakage between the piston and the piston band can be eliminated, and the damping force as designed can be obtained.

Note that the present invention can also be implemented when the hydraulic shock absorber is of a single cylinder type.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the main parts of the hydraulic shock absorber according to the present invention, Figure 2 is a perspective view of the piston band, and Figure 3 is a perspective view of the piston band.
Figures a and b are explanatory diagrams of usage conditions, Figures 4 and 5
The figure is a sectional view showing the main parts of another example. 10; cylinder, 12; piston, 14,5
4, 66; Seal member, 34, 56, 62; Elastic body, 36, 58, 64; Piston band.

Claims (1)

[Scope of utility model registration request] A hydraulic shock absorber in which a piston is movably disposed within a cylinder, and includes a sealing member disposed between the cylinder and the piston, the sealing member being an elastic body fixed to the outer peripheral surface of the piston. and a piston band fixed to the outer peripheral surface of the elastic body and in contact with the inner peripheral surface of the cylinder, the piston bands are butted against each other with a gap in the circumferential direction, and are expandable and contractible in the radial direction. Yes, a hydraulic shock absorber.