Brakes – Internal-resistance motion retarder – Having a thrust member with a variable volume chamber
Reexamination Certificate
1999-05-19
2001-04-10
Schwartz, Christopher P. (Department: 3613)
Brakes
Internal-resistance motion retarder
Having a thrust member with a variable volume chamber
C267S118000
Reexamination Certificate
active
06213263
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an oil shock absorber system for motorcycles or automobiles and in particular for vehicles that are used either for racing or for all-terrain driving.
An oil shock absorber that comprises a mobile piston in a cylinder which, during its compression travel, displaces the oil that is contained in a chamber toward, on the one hand, a reservoir and, on the other, a second chamber that is located on the other side of the piston, is known from U.S. patent application Ser. No. 4,958,706. The path of the oil toward the second chamber that is located on the other side of the piston runs through valves for adjusting the resilience characteristics of the shock absorber. The pressure of the oil that is driven into the reservoir is balanced by a pocket that holds a pressurized gas and that plays, as it were, a role equivalent to that of the spring in the spring shock absorbers of the prior art. Access to the chamber of the reservoir is limited by, on the one hand, a system that can be adjusted by a screw for adjusting the compression rate, and, on the other, a valve for protection against excessive pressure that is set to withstand a maximum pressure of about 140 Kg/cm
2
(2000 psi).
A shock absorber system that comprises a cylinder in which a mobile piston delimits two working volumes is also known from International Patent Application WO 94 12360. Each volume is connected, via a pipe, to an intermediate volume. The two intermediate volumes each communicate by three orifices with the same control chamber. The three orifices respectively comprise a valve for regulating the flow of oil from the intermediate volume to the control chamber, an adjustable nonreturn valve that constitutes a hydraulic brake, and a valve that allows a permanent passage from the control chamber to the intermediate volume. This relatively complex system makes it possible to adjust the characteristics of compression and of stress relief of a shock absorber independently, but it does not allow optimum adjustment of the shock absorber for operations in a range of displacement speeds of the piston that lies between low speeds and hydraulic brake speeds.
This invention relates to an oil reservoir that can be used with such a shock absorber or with other simpler or more complex shock absorber types. Actually, it has been noted that in these shock absorber systems, an elastic element that generally consists of a rubber ring is always provided on the shock absorber, between, on the one hand, ring (
11
) that is placed at the end of rod (
10
) of the piston that is adjacent to attachment ring (
12
) on the frame of the vehicle and, on the other hand, lower outside surface (
151
) of cylindrical body (
15
) that constitutes the compression chamber which forms the shock absorber stop that is encountered under extreme operating conditions. Actually, since the shock absorber is protected against excessive pressure, the valve of the reservoir is likely to open when the vehicle falls back after a major bounce, and, in this case, the only protection for the shock absorber is the elastic bearing that is located between cylinder (
15
) and ring (
11
).
The elastic bearing has the drawback of generating uncontrollable bouncing phenomena for the driver which sometimes bring the vehicle to tip violently to the front.
SUMMARY OF THE INVENTION
A first object of the invention is to propose a shock absorber system that makes it possible to eliminate these drawbacks and to improve the response characteristics of the shock absorber during compression phases while retaining the advantages and characteristics of oil shock absorbers.
This object is achieved by the fact that the oil shock absorber system that consists of a piston that is mounted at the end of a movable rod that moves in a cylindrical hollow body by driving the oil that is between the piston and the bottom of the hollow body of the shock absorber toward a deformable reserve chamber, to the outside of which a pressurized gas is applied, whereby the oil that is evacuated to the reserve chamber via at least two different orifices, depending on the displacement speeds of the piston, is characterized in that the path of the oil runs through an intermediate chamber of a given volume and the orifices are located between the reserve chamber and the intermediate chamber, whereby at least one of the orifices or the first orifice is blocked by an adjustable nonreturn valve that constitutes an adjustable hydraulic brake so as to allow the oil to evacuate only when the pressure that is exerted by the piston on the oil is such that it exceeds the vehicle's most extreme anticipated operating conditions, and in that a second adjustable nonreturn valve blocks a second orifice that is located between the intermediate chamber and the reserve chamber, whereby the second adjustable nonreturn valve is adjusted for a range of displacement speeds of the piston that lies between low speeds and hydraulic brake speeds.
According to another particular feature, a third orifice that is provided with an adjustable constriction makes it possible at low speeds to evacuate oil from the intermediate chamber to the reserve chamber.
According to another particular feature, the first and second valves comprise a screw element that is extended by a notched rod uniformly over a given height of its periphery and that supports on the end of the rod means for attaching a holding cap, whereby a sealing washer (
354
) and an elastic means are held between the holding cap and the notched part, and the elastic means presses the sealing washer with a specific force on the seat of the respective orifice that is associated with the valve.
According to another particular feature, the notched part works with a ball on which elastic means act to constitute an adjusting catch.
According to another particular feature, the intermediate chamber consists of an annular groove that is formed in a cylindrical ring that is intended to close the open end of the reservoir, whereby the cylindrical ring is provided with holes that run through the ring and the annular groove, whereby the holes comprise, on the outside of the reservoir, threading for the screw element and means that make it possible to ensure sealing between the screw body and the hole.
According to another particular feature, the elastic means that press the sealing washer against the seat of the hole consist of a stack of several beleville washers that are mounted two by two opposite one another.
According to another particular feature, the elastic means for the high-speed screw consist of a stack of beleville washers with a thickness of between 0.20 mm and 0.45 mm.
According to another particular feature, the elastic means for the hydraulic stop screw consist of a stack of beleville washers with a thickness of between 0.45 mm and 1 mm, with a greater thickness for the washers of the stop screw than that of the washers of the high-speed screw.
REFERENCES:
patent: 4936424 (1990-06-01), Costa
patent: 0 237 085 (1987-09-01), None
patent: 0 542 282 (1993-05-01), None
patent: 2 084 289 (1982-04-01), None
patent: 94 12360 (1994-06-01), None
Donerre Amortisseur
Nixon & Vanderhye
Schwartz Christopher P.
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