Shock absorber

Abstract

Disclosed herein is a shock absorber for damping vibration transmitted to a vehicle according to a road state. The shock absorber includes a cylinder and a piston valve disposed within the cylinder and connected to a piston rod to divide the cylinder into a first chamber and a second chamber. The piston rod includes a hollow chamber formed within the piston rod, first and second orifices formed in upper and lower ends of the hollow chamber and connected to the first and second chambers, respectively, a floating piston disposed within the hollow chamber to move up and down and to divide the hollow chamber into upper and lower chambers, and a moving mechanism formed in the hollow chamber to move an operating fluid to upper and lower portions of the floating piston. The shock absorber can change a damping force according to a displacement of the piston rod, thereby improving driving comfort and stability of the vehicle.

Description

BACKGROUND OF THE INVENTION[0001]1. Technical Field[0002]The present disclosure generally relates to shock absorbers for damping vibration transmitted to a vehicle according to a road state and, more particularly, to a shock absorber capable of changing a damping force according to a displacement of a piston rod.[0003]2. Description of the Related Art[0004]Generally, a vehicle is provided with a suspension system for enhancing driving comfort by buffering impact or vibration transmitted to an axle from a road during driving. One component constituting the suspension system is a shock absorber. The shock absorber is disposed between the axle and a vehicle body. The shock absorber includes a cylinder and a piston rod reciprocating within the cylinder. The cylinder is filled with an operating fluid, such as gas or oil, such that the operating fluid is moved by a piston valve secured to one end of the piston rod to generate a damping force.[0005]A conventional shock absorber has a restr...

AI Technical Summary

Benefits of technology

[0013]According to one aspect a shock absorber is provided that includes a floating piston disposed within a hollow chamber of a piston rod to reduce a damping force and can significantly reduce the damping force in a section where the piston rod moves repetitiously.

[0014]Another aspect of the present invention is to provide a shock absorber that can gradually reduce the damping force according to a displacement of the piston rod.

[0015]A further aspect of the present invention is to provide a shock absorber that can prevent a stick slip phenomenon.

Problems solved by technology

Therefore, a low damping force characteristic can improve driving comfort but does not ensure stability of the vehicle, whereas a high damping force characteristic can maintain the stable posture of the vehicle but entails deterioration of driving comfort.

As such, the conventional shock absorber is incapable of controlling damping force characteristics in response to variation of the road state or the posture of the vehicle.

However, the hollow chamber 20 has a restricted size so that a range of motion of the floating piston 22 is limited, thereby providing a low effect in reduction of the damping force.

Further, when increasing the size of the hollow chamber 20 to improve the effect of reducing the damping force, there are problems of a manufacturing cost increase and a durability deterioration of the piston rod 14.

Additionally, the conventional shock absorber undergoes friction between the outer surface of the floating piston and the inner surface of the hollow chamber while the floating piston moves up and down within the hollow chamber to cause an inefficient initial movement and a stick slip phenomenon between the floating piston and the hollow chamber, thereby lowering driving comfort.

Furthermore, when the floating piston contacts the upper end or the lower end of the upper chamber or the lower chamber, the conventional shock absorber generates noise, thereby deteriorating quality satisfaction.

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