Shock absorber

Details Shock absorber Shock absorber

1999-10-14

2001-04-17

Schwartz, Chris (Department: 3613)

Brakes

Internal-resistance motion retarder

Motion damped from condition detected outside of retarder

C188S322150

Reexamination Certificate

active

06216830

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shock absorber adapted for use in a vehicle suspension system for vibration attenuation.
2. Description of the Prior Art
Generally, a suspension system applied to a vehicle is provided with a shock absorber constructed to cushion a shock by way of a coil spring and to prevent repeated vibrations generated during the shock buffering of the coil spring.
In other words, the coil spring serves to cushion the shock and the like from the road surface to transmit same to a body of the vehicle and the repeated vibrations according to the shock buffering action of the coil spring are attenuated to thereby maintain vehicle safety while running and to reduce swaying, such rolling, and pitching of the vehicle.
The shock absorber is dually formed, as illustrated in
FIG. 5
, with inner and outer tubes
50
and
51
, between which there are provided a housing
53
formed with a storage chamber
52
, a rod
54
arranged to pierce the inner tube
50
, a piston
57
disposed at a longitudinal end of the rod
54
to divide the inner tube
50
into a first and a second chamber
55
and
56
and a foot valve
58
equipped at a longitudinal end of the inner tube
50
.
Furthermore, the shock absorber is formed with a vibroisolating tube
59
to encompass an exterior surface of the outer tube
51
, and a bushing
60
for connecting wheels and body (not shown) is installed at a longitudinal end of the rod
54
and at facing end of the outer tube
51
. The inner and outer tubes
50
and
51
are filled with fluid (F).
The piston
57
is installed with an open/close valve
61
in order to generate an attenuating force by restricting movement of fluid (F) filled in the inner tube
50
, where, the piston
57
includes, as illustrated in
FIG. 6
, a plurality of orifices
62
formed at the piston
57
and a plate-like open/close valve for blocking the orifices
62
during compression and for opening the orifices during expansion.
Now, operation of the shock absorber thus constructed will be described in detail. When wheels are bounced while a vehicle is running, the housing
53
connected to the wheels (suspension arms and the like) rises, by which the piston
57
moves toward a direction of compressing the second chamber
56
. When the second chamber
56
is compressed by the piston
57
, the open/close valve
61
maintains a closeness, where the fluid compressed in the second chamber
56
is infused into the storing chamber
52
via the foot valve
58
to thereby enable the piston
57
to descend.
When the wheels are rebounded to lower the housing
53
while the piston
57
is descended, the piston
57
is resulted to go upwards, and when the piston
57
is ascended, the open/close valve
61
blocking the orifices
62
is bent to open the orifices
62
.
When the orifices
62
are opened, the fluid (F) moves through the orifices
62
to move towards the second chamber
56
, where, an attenuating force is generated which is as strong as fluid resistance generated while passing through the orifices
62
and the open/close valve
61
.
The open/close valve
61
is usually made of same material in plate-like shape. The attenuating force relative to speed of the piston
57
is linearly increased at a predetermined ratio but suddenly turns upwards at a strain point (V).
In other words, the attenuating force is increased relatively slow before the strain point (V) but is suddenly increased past the strain point (V). this linear ratio change of the attenuating force is caused by a phenomenon where, when the plate-like open/close valve
61
is bent to exceed a predetermined extent, resilience thereof is markedly increased, which remarkably increases fluid resistance according to the open/close valve
61
, thereby changing the linear ratio of the attenuating force.
SUMMARY OF THE INVENTION
However, there is a problem in that when an attenuating force of an open/close valve is not linearly changed due to a part where resilience of the open/close valve disposed at the piston thus described is suddenly increased, a sudden increase or decrease of attenuating force at the strain point (V) is realized, such that an abnormal vibration and the like are generated at the strain point (V) to thereby decrease rideability and running safety of a vehicle.
The present invention is disclosed to solve the aforementioned problems and it is an object of the present invention to provide a shock absorber constructed to prevent a sudden increase or decrease of attenuating force at a predetermined position during operation of vibration attenuation at the shock absorber to thereby increase the rideability and running safety of a vehicle.
In accordance with the object of the present invention, there is provided a shock absorber disposed with a piston having a cylindrically closed housing filled with fluid where an attenuating force is generated by a fluid resistance caused by the fluid moving through orifices, the shock absorber comprising:
a valve formed to horizontally move on upper/bottom surfaces of the piston to thereby open and close the orifices;
guide means disposed between the valve and the piston to enable the piston to horizontally move and to prevent the piston from breaking away to the other direction; and
actuating means for horizontally changing a force applied to the fluid to move the valve when the piston is moved toward an expanding direction.


REFERENCES:
patent: 3706362 (1972-12-01), Faure
patent: 4061295 (1977-12-01), Somm
patent: 4520908 (1985-06-01), Carpenter
patent: 5850896 (1998-12-01), Tanaka
patent: 6003644 (1999-12-01), Tanaka

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