JPH0514127B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorber, and more particularly to a shock absorber having damping characteristics suitable for automobile suspension.

From the perspective of maneuverability and stability, shock absorbers in automobile suspensions are effective against low-frequency vibrations such as rolling, pitching, and bouncing, which are relatively slow motions, and from the perspective of ride comfort, they are relatively fast. It is preferable to have damping force characteristics that are not very effective against high-frequency vibrations caused by rough movements.

However, the conventional valve structure for generating damping force generally has a port on the piston and biases the metal valve body to the end of the port using a coil spring, so the damping force characteristics depend on the port. The damping force characteristics cannot be changed as the vibration frequency changes.

Although there are some types with variable damping force characteristics, these mechanically change the mounting load, etc., and have problems such as being expensive and complicated to operate.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shock absorber equipped with a valve structure that can automatically change damping force characteristics as the vibration frequency changes and can be manufactured at low cost.

The present invention is a shock absorber in which a piston is movably arranged in a cylinder, two liquid chambers are defined in one side and the other side of the piston, and a piston rod is connected to the piston, and the piston is connected to the piston rod. The rubber body includes a rubber body disposed surrounding the piston rod, and a pair of annular plates movably attached to the piston rod in the axial direction thereof and disposed on one side and the other side of the rubber body, respectively. Communication between the two liquid chambers and restriction of communication.

When the shock absorber is used, when the vibration frequency applied to the shock absorber changes, the rubber body changes its spring constant. Furthermore, fluid pressure generated in either of the fluid chambers causes one of the plates to move in the axial direction of the piston rod and compress the rubber body, thereby restricting communication between the two fluid chambers. In this way, preferable damping force characteristics can be obtained.

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

As shown in FIG. 1, the shock absorber of the present invention includes a cylinder 10 filled with a liquid such as oil.
A piston 12 is movably disposed within the piston 12, a liquid chamber 14 is defined above the piston 12, a liquid chamber 16 is defined below the piston 12, and a lower end 20 of a piston rod 18 is connected to the piston 12.

The illustrated example is a so-called monotube type shock absorber. Therefore, cylinder 1
0, a free piston 22 is located outside the piston 12 and spaced downward from the piston 12.
is slidably arranged.

The piston 12 includes a rubber body 24 made of rubber and a pair of plates 26. Rubber body 2
4 is arranged around the end 20 of the piston rod 18. In the example shown in FIG. 1, the rubber body 24 is cylindrical, and its outer diameter gradually increases toward the center of its outer circumferential surface 28, and its inner diameter gradually decreases toward the center of its inner circumferential surface 29. It is formed like this. This is to facilitate deformation of the rubber body 24 due to hydraulic pressure. The inner circumferential surface 29 is fitted onto the end 20 of the piston rod 18. Further, the outer circumferential surface 28 defines a maximum outer diameter dimension such that a liquid passage 30 is formed between the outer circumferential surface 28 and the inner circumferential surface 11 of the cylinder 10 when the rubber body 24 is disposed at the end portion 20. .

The pair of plates 26 are annularly formed of metal or hard plastic harder than the rubber body 24, and are inserted into the end 20 of the piston rod 18 so as to be movable in the axial direction. The other side is the rubber body 2
4, respectively. The pair of plates 26 have an outer diameter such that each plate 26 substantially contacts the upper or lower surface of the rubber body 24 . This plate 26 allows uniform deformation of the rubber body 24.

In the example shown in FIG. 2, the rubber body 34 has a liquid passageway 36 within itself. The outer circumferential surface 38 and inner circumferential surface 39 of the rubber body 34 are respectively connected to the cylinder 1.
0 inner peripheral surface 11, end 20 of piston rod 18
is in contact with the outer circumferential surface 42 of. It is preferable that a plurality of passages 36 be provided at equal intervals in the circumferential direction of the rubber body 34. A pair of plates 44 arranged above and below the rubber body 34 have holes 46 at positions facing the passages 36 of the rubber body 34 .

In the example shown in FIG. 3, a liquid passage 56 is formed between the rubber body 54 and a cylindrical stopper 55 fitted to the end portion 20. The outer circumferential surface 58 of the rubber body 54 is in contact with the inner circumferential surface 11 of the cylinder 10. A pair of plates 60 disposed above and below the rubber body 54 are provided with a notch 62 extending from a central hole.

A nut 32 is screwed into the piston rod 18, and this nut 32 and the shoulder 1 of the piston rod 18
A pair of plates 26 and a rubber body 24 are sandwiched between the plate 26 and the rubber body 9. During use, piston rod 1
8 is subjected to vibration, the rubber body 24 changes its spring constant according to the frequency of the vibration, so even if the piston speed is constant, the generated damping force changes as the frequency changes, as shown in A in Figure 4. It will change with the. On the other hand, in a conventional valve structure using a metal valve body and a coil spring, the damping force is constant, as shown in B in the figure.

During use, for example, when the piston rod 18 moves in the retracting direction, the liquid in the liquid chamber 16 flows through the passage 30 into the liquid chamber 14 as shown by arrow C, and the liquid in the liquid chamber 1
The hydraulic pressure inside 6 increases. When the liquid pressure in the liquid chamber 16 increases, the lower plate 26 moves upward toward the rubber body 2.
Move while contracting 4. Due to the movement of the lower plate 26, the rubber body 24 swells in the radial direction by an amount equivalent to the volume that the axial length of the rubber body 24 has shrunk, and the effective cross-sectional area of the passage 30 becomes smaller. The damping force generated by the flowing liquid becomes higher. Contrary to the above, when the piston rod 18 moves in the direction of extension, the liquid flows in the direction of arrow D, and the upper plate 26 contracts the rubber body 24.

According to the present invention, since the piston is composed of a rubber body and a pair of plates, the spring constant of the rubber body automatically changes depending on the frequency of vibrations applied to the piston via the piston rod, and damping occurs. power can be changed. In this case, the damping force becomes larger as the frequency of the vibration becomes lower.
Therefore, when the shock absorber of the present invention is installed in the suspension of an automobile, vibrations such as rolling, pitching, and bouncing are effectively damped, and maneuverability and stability can be improved. On the other hand, since damping is not very effective against high-frequency rough vibrations, riding comfort can also be improved.

Further, in the present invention, since the valve action is performed by utilizing the deformation of the rubber body itself, a coil spring or the like is not required, and the valve can be manufactured at low cost.

Note that, instead of the above example, the present invention is applied to a so-called twin engine which includes an inner cylinder and an outer cylinder arranged at a distance radially outward of the inner cylinder, and the space is used as a liquid reservoir chamber. It can also be applied to tube type shock absorbers. In this case, when the gas sealed in the upper part of the reservoir chamber is at atmospheric pressure, when the piston rod contracts, the liquid chamber
Since no pressure is generated inside the inner cylinder, a known base valve assembly is placed at the bottom of the inner cylinder, or a throttle is provided in the inner cylinder, and the inside of the inner cylinder communicates with the reservoir chamber through this throttle. I'll do what I do.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the essential parts of a shock absorber according to the present invention, FIGS. 2 and 3 are cross-sectional views showing the main parts of other examples, and FIG. 4 is a characteristic diagram of damping force. 10...Cylinder, 12...Piston, 14,
16...liquid chamber, 18...piston rod, 20...
...End part, 24, 34, 54...Rubber body, 26, 4
4,60...Plate, 30,36,56...Aisle.

Claims (1)

[Claims] 1 A shock absorber comprising a piston movably arranged in a cylinder, two liquid chambers defined in one side and the other side of the piston, and a piston rod connected to the piston, the piston surrounding the piston rod. and a pair of annular plates that are movably attached to the piston rod in the axial direction thereof and are respectively disposed on one side and the other side of the rubber body; A shock absorber that communicates and limits communication between liquid chambers.