Fluid pressure shock absorber

Abstract

An object of the present invention is to generate a stable damping force and enhance durability of a main valve in a hydraulic shock absorber in which valve opening of the main valve is controlled by an inner pressure of a backpressure chamber. A first piston 3 and a second piston 4 coupled to a piston rod 10 are fitted in a cylinder 2 such that a piston chamber 2 C is defined between the first and second pistons 3, 4 . An extension-side main valve 18 and a compression-side main valve 23 are provided in the piston chamber 2 C. Valve opening of the main valves is controlled by an extension-side backpressure chamber 19 and a compression-side backpressure chamber 24 . A compression-side check valve 13 and an extension-side check valve 16 are provided at the first piston 3 and the second piston 4 .; During an extension stroke of the piston rod 10 , the compression-side check valve 13 is closed, whereby action of a pressure of a cylinder upper chamber 2 A on the compression-side main valve 23 is prevented. During a compression stroke of the piston rod 10 , the extension-side check valve 16 is closed, whereby action of a pressure of a cylinder lower chamber 2 B on the extension-side main valve 18 is prevented. Accordingly, it is possible to generate a stable damping force, and enhance durability of the extension-side main valve 18 and the compression-side main valve 23.

Description

technical field [0001] The present invention relates to a fluid pressure damper such as an oil damper mounted on a suspension device of a vehicle such as a motor vehicle, and more particularly to a fluid pressure damper having a back pressure chamber that controls the flow of a main valve that generates a damping force valve opening pressure. Background technique [0002] Generally, a cylinder-type hydraulic shock absorber mounted on a suspension device of a vehicle such as a motor vehicle has a piston connected to a piston rod slidably embedded in a cylinder filled with oil, and a throttling valve is provided on the piston part. A damping force generating mechanism composed of holes and disc valves. The orifice and disc valve are used to control the flow of oil produced by the sliding of the piston in the cylinder with the expansion and contraction of the piston rod to generate damping force. In the low-speed region where the piston speed is low, the orifice produces a da...

AI Technical Summary

Problems solved by technology

[0003] In the above-mentioned existing hydraulic shock absorber, the damping force in the low-speed region where the piston speed is low depends on the oil passage area of ​​the orifice, and the damping force in the high-speed region depends on the preset valve opening pressure of the disc valve. Therefore, There are the following problems: the degree of freedom in setting the damping force characteristics is low; if you want to obtain a small damping force in the low-speed area where the piston speed is low, the damping force in the high-speed area is insufficient; if you want to obtain a large damping force in the high-speed area, the Excessive damping force in the low speed range

In the extremely low speed region where the piston speed is extremely low, the pressure introduced through the check valve cannot sufficiently increase the pressure of the back pressure chamber, so it is difficult to reliably prevent the main valve from opening, and the damping force is likely to be unstable.

In addition, the back pressure chambers on both the expansion side and the contraction side are pressurized in both the expansion and contraction strokes, and the load is repeatedly applied to the main valve accordingly, so the durability of the main valve is reduced.

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