Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
1998-11-30
2001-11-06
Oberleitner, Robert J. (Department: 3613)
Spring devices
Vehicle
Comprising compressible fluid
C267S064260, C188S322170
Reexamination Certificate
active
06311962
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to shock absorbers.
Conventional automotive vehicles typically have separate suspension springs and separate simple shock absorbers. Simple shock absorbers, which provide damping only, are typically oil-filled cylinders within which a vented piston is mounted. The piston is connected to a shaft which extends out of one end of the cylinder. The outer end of the shaft is mounted to one point on the vehicle; the other end of the cylinder is mounted to another point on the vehicle so that the shock is parallel to the action of the suspension spring.
Another type of shock absorber, which is the type commonly used with motorcycles, off-road vehicles, competition automotive vehicles and off-road bicycles, combines at least part of the suspension function and the shock absorbing function in one unit. This second type of shock absorber commonly uses a spring unit to provide all or part of the suspension function coupled with a damping unit to provide the damping function. Conventional shock absorber designs commonly incorporate an external coil spring, an internal air spring, or an internal bladder to provide the suspension function.
SUMMARY OF THE INVENTION
The present invention provides a shock absorber system which is much lighter than conventional external metal coil spring designs and is much simpler and compact than air bladder designs.
The present shock absorber includes an external air cylinder spring unit and a damping fluid cylinder unit coupled together by a shaft, with the damping fluid cylinder unit being telescopically received within the air cylinder spring unit. A movement damping element, preferably a vented piston, is movably mounted within the damping fluid cylinder. The damping cylinder unit also includes a movable seal, preferably a floating piston, separating a damping fluid on one side from a gas on the other.
As the shock absorber extends and contracts, the movement of the shaft causes the vented piston to move back and forth within the damping fluid cylinder, thus damping the extension and contraction of the shock absorber. As the shaft moves back and forth, however, the volume of the shaft received within the damping cylinder changes. This change in the volume of the shaft received within the damping fluid cylinder is accommodated by the movement of the floating piston, wherein a gas chamber on one side of the floating piston alternately expands and contracts in response to the movement of the shaft.
A dynamic or sliding seal between the inner surface of the air cylinder unit and the outer surface of the damping fluid cylinder unit creates a sealed air chamber, acting as an external air cylinder spring. As only one large diameter seal is used to seal the air chamber, this greatly reduces friction from that present in existing systems. An additional advantage of the present design is that the spring rate can be adjusted by changing the air pressure in the air cylinder unit without affecting the performance of the damper unit.
The present invention finds particular utility for use with on- and off-road vehicles. However, the invention can also be used for other shock-absorbing tasks, such as instrument mounting structures and transportation vibration isolators.
Other features and advantages of the present invention will appear from the following description in which the preferred embodiments have been set forth in detail in conjunction with the accompanying drawings.
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1999 Sid XC, SL and XL Owner's Manual, Rock Shox, pp. 1-21.
Fox Factory, Inc.
Hann James F.
Haynes Beffel & Wolfeld LLP
Oberleitner Robert J.
Williams Thomas J.
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