Brakes – Internal-resistance motion retarder – Piezoelectric
Reexamination Certificate
1999-12-17
2001-10-09
Oberleitner, Robert J. (Department: 3613)
Brakes
Internal-resistance motion retarder
Piezoelectric
C188S322220, C188S266200
Reexamination Certificate
active
06298958
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a shock absorber of an automotive suspension system, and in particular, to a hydraulic shock absorber capable of controlling a damping force thereof.
(b) Description of the Related Art
Shock absorbers are mounted between a vehicle frame and a suspension, and operate on the principle of forcing fluid through restricted openings on both extension strokes and compression strokes.
In general, a hydraulic shock absorber includes a cylinder filled with hydraulic fluid and a piston inserted into the cylinder. The piston consists of a piston rod and a plunger assembly which is slidably fitted into the cylinder so as to divide the inside of the cylinder into two compartments. The plunger assembly is provided with a main orifice and a bypass orifice which provide communication between the two compartments in the cylinder, and the orifices have respective valve mechanisms for controlling the amount of fluid communication.
FIG. 5
shows a prior art shock absorber capable of adjusting damping force thereof. As shown in
FIG. 5
, the shock absorber comprises a cylinder
112
connected to a suspension (not shown) and a piston
114
inserted into the cylinder
112
, with an end of piston
114
outside the cylinder
112
being connected to a vehicle body (not shown). The piston
114
includes a cylindrical piston rod
115
and rotary valve
124
slidably fitted in the cylinder
116
. In a space inside the piston rod
115
with chamber
126
, a step motor
122
, gear mechanism
120
, and clutch are located such that the rotary valve
124
receives rotary torque from the step motor
122
by way of a control rod
118
connecting the gear mechanism
120
to the clutch. Also, upper and lower chambers divided by the rotary valve
124
communicate through orifices
119
formed in a valve case, and the amount of fluid
128
passing through the orifices
119
can be adjusted by rotating a valve plate which varies the size of the orifices according to the amount of rotation of the step motor
122
. Accordingly, the damping force of the shock absorber can be adjusted as needed.
However, since this shock absorber uses complicated mechanical structures such as a motor, gear mechanism, clutch, and so forth, there are difficulties in design, and it is impossible to precisely adjust the damping force.
Furthermore, the complicated mechanical structure delays response time of adjustments to the damping force on an uneven road.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to solve the above problems of the prior art.
It is an object of the present invention to provide an improved shock absorber capable of precisely adjusting damping force thereof and promptly responding to road conditions.
To achieve the above object, an automatically adjustable damping force shock absorber of the present invention comprises an outer cylinder, an inner cylinder provided in the outer cylinder, and a piston inserted into the inner cylinder. The piston comprises a plunger assembly slidably fitted in the inner cylinder so as to divide the inner cylinder into two compartments, and provided with orifices on a side wall thereof and several one way valves on a upper and lower walls thereof. A cylindrical piston rod is connected at one end of the plunger assembly; a control valve is provided in the plunger assembly for controlling the amount of fluid through the orifices and one way valves of the plunger assembly; and an electric power supplier is connected to the control valve by a power supply cable. The electric power supplier comprises an accelerometer for detecting compression and extension of the shock absorber and responsively producing an acceleration level signal, an amplifier for amplifying the acceleration level signal, and a voltage generator for generating voltage on the basis of the acceleration signal.
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patent: 4729459 (1988-03-01), Inagaki et al.
patent: 4781477 (1988-11-01), Nagasawa
patent: 4828220 (1989-05-01), Hashimoto
patent: 5029677 (1991-07-01), Mitsui
patent: 5203537 (1993-04-01), Jacobs et al.
patent: 5233834 (1993-08-01), Tsukamoto
patent: 5303804 (1994-04-01), Spiess
patent: 5409089 (1995-04-01), Rapp et al.
patent: 5657840 (1997-08-01), Lizell
patent: 5996745 (1999-12-01), Jones, Jr. et al.
patent: 6003644 (1999-12-01), Tanaka
patent: 6152271 (2000-11-01), Achmad
patent: 2154700-A (1995-09-01), None
Burch Melody M.
Hyundai Motor Company
Oberleitner Robert J.
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