Brakes – Internal-resistance motion retarder – With fluid regulated in response to inertia of valve member
Reexamination Certificate
1999-02-04
2001-07-03
Graham, Matthew C. (Department: 3613)
Brakes
Internal-resistance motion retarder
With fluid regulated in response to inertia of valve member
C188S314000, C188S322150
Reexamination Certificate
active
06253888
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to hydraulic shock absorbers. More specifically, the present invention relates to a method and apparatus for increasing the performance of hydraulic shock absorbers by providing acceleration sensitive damping through the regulation of fluid flow within the shock absorber.
2. Description of the Related Art
Shock absorbers are commonly used in vehicle suspension systems to absorb unwanted vibrations which occur during driving. Specifically, shock absorbers are generally connected between the body (sprung mass) and the suspension (unsprung mass) of the vehicle to “dampen” vibrations transmitted from the suspension to the body.
Vehicle shock absorbers usually have a hollow cylinder defining an internal chamber, which is divided into a compression compartment and a rebound compartment by a piston assembly slidably positioned in the internal chamber. The shock absorber includes internal valving which permits fluid to flow between the compression and rebound compartments as the piston moves within the internal chamber. One end of the cylinder is closed and is typically connected to the vehicle suspension by a suitable linkage. A piston rod extends through a seal assembly mounted in the other end of the cylinder and has its inner end connected to the piston and its outer end connected to the vehicle body by a suitable connector.
The piston assembly limits the flow of damping fluid within the internal chamber of the shock absorber during compression and extension of the shock, thereby providing a damping force which “smooths” or “dampens” vibrations transmitted from the suspension to the body. The damping characteristics of a shock absorber are determined by the fluid pressure differential across the piston required to drive the fluid between the compression, rebound and reservoir compartments. This pressure differential and resulting flow rate, in turn, controls the speed at which the piston may move in the cylinder responsive to the external forces applied to the shock absorber. The greater the degree to which the flow of damping fluid is restricted by the piston assembly, the greater the damping forces which are provided by the shock absorber. Accordingly, a “soft” compression and rebound stroke is produced when the flow of damping fluid in the working internal chamber is relatively unrestricted. By contrast, a “firm” compression and rebound stroke is produced when there is an increased restriction in the flow of damping fluid in the working internal chamber.
Different driving characteristics, such as ride comfort, vehicle handling, and road holding ability depend on the amount of damping force provided by the vehicle's shock absorbers. The amount of damping force required to meet a particular set of driving characteristics is, in turn, dependent on driving surface conditions. There are sudden and short-lived driving conditions which call for increased damping. For example, a pothole results in a rapid rebound stroke followed by a jarring compression stroke. The jarring is in part caused by an unnecessarily large rebound stroke due to the rapid falling of the suspension into the pothole. There exists a need in the art for a shock absorber with damping that adjusts automatically in response to inordinately rapid accelerations of shock absorber components.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method and apparatus for providing acceleration sensitive damping.
It is another object of the present invention to provide a method and apparatus for adjusting shock absorption damping based on the acceleration of shock absorber components.
It is further object of the present invention to provide a method and apparatus for providing acceleration sensitive shock absorption damping through the use of acceleration sensitive mechanical members to regulate fluid flow between the internal chambers of a shock absorber.
One or more of the foregoing objects is met in whole or in part by a preferred embodiment of the present invention that provides a method and apparatus for improved shock absorption with acceleration sensitive damping. The shock absorber has a reservoir compartment and a fluid-filled internal chamber divided into a compression compartment and a rebound compartment by a movable piston. A piston rod is connected to the piston and extends through a seal in the rebound end of the internal chamber. The shock absorber contains flow passages connecting and allowing fluid to flow between the reservoir compartment, the compression compartment and the rebound compartment. Fluid flow in the flow passages, which is directly related to the relative motion between the shock main body and the piston rod, is allowed or inhibited based on the acceleration of shock absorber components. An acceleration sensitive mechanism is provided which is slidably mounted near one or more of the flow passages. The mechanism may be sensitive to accelerations of either the shock main body or the piston rod. The mechanism is normally biased to allow fluid flow in the flow passages. When accelerations above design thresholds are experienced, the mechanism moves to inhibit fluid flow in the flow passages, thereby inhibiting the relative motion between the shock body and the piston rod, and thus providing acceleration sensitive damping.
By use of the present invention, shock absorption damping may be adjusted in real-time in response to sudden driving surface anomalies. These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.
REFERENCES:
patent: 3338347 (1967-08-01), Avner
patent: 4084667 (1978-04-01), Kurrat
patent: 4850461 (1989-07-01), Rubel
patent: 5070470 (1991-12-01), Johnston et al.
patent: 5248014 (1993-09-01), Ashiba
patent: 5618248 (1997-04-01), Huang
patent: 5833036 (1998-11-01), Gillespie
Bell Stephen H.
Carlstedt Robert P.
Gabriel Ride Control Products, Inc.
Graham Matthew C.
McAndrews Held & Malloy Ltd.
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