Brakes – Internal-resistance motion retarder – Having a thrust member with a variable volume chamber
Reexamination Certificate
2000-04-21
2002-02-12
Oberleitner, Robert J. (Department: 3613)
Brakes
Internal-resistance motion retarder
Having a thrust member with a variable volume chamber
C188S322160, C188S315000, C188S373000
Reexamination Certificate
active
06345707
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
The present invention relates to a frictionless hydraulic damper wherein the piston rod extends only through one end wall and the damper has a closed sealed hydraulic circuit.
By way of background, the prior art discloses numerous frictionless hydraulic dampers in U.S. Pat. Nos. 4,638,895, 4,768,627 and 4,815,574. In all of these patents the hydraulic fluid is confined within a closed circuit which includes bellows seals between the piston rod and other parts of the damper. In these patents all of the fluid which is used for damping is confined within a single cylinder and various bellows seals. The closed circuit could be achieved because the piston rod was double-ended and extended through the end walls of the cylinder. However, the foregoing type of sealed frictionless arrangement could not be achieved with a damper wherein the piston rod extended only through one end wall of the cylinder.
BRIEF SUMMARY OF THE INVENTION
It is one object of the present invention to provide a frictionless hydraulic damper wherein the piston rod extends only through one end wall of the cylinder and in which the hydraulic fluid is completely confined within a closed sealed circuit.
It is another object of the present invention to provide a frictionless damper as described in the preceding object and in which hydraulic fluid can circulate in a closed sealed circuit which includes an annular space between inner and outer cylinders.
Another object of the present invention is to provide a frictionless hydraulic damper wherein an inner damping cylinder is concentrically positioned within an outer cylinder with an annular space therebetween which conducts damping fluid externally of opposite end walls of the damping cylinder so that heat which is generated as a result of the damping action is dissipated from the relatively large surface area of the outer cylinder.
A still further object of the present invention is to provide an improved frictionless damper wherein the piston rod is supported by a ball bearing assembly. Other objects and attendant advantages of the present invention will readily be perceived hereafter.
The present invention relates to a hydraulic damper comprising a cylinder, first and second end walls in said cylinder, a piston rod extending only through said first end wall, a first portion of said piston on one side of said first end wall and within said cylinder, a second portion of said piston on the opposite side of said first end wall and external to said cylinder, a piston head on said first portion of said piston rod within said cylinder, a first chamber in said cylinder between said piston head and said first end wall, a second chamber in said cylinder between said piston head and said second end wall, an accumulator in communication with said second chamber, a fluid-containing seal between said first end wall and said second portion of said piston rod, and a closed fluid circuit between said accumulator and said fluid-containing seal.
The present invention also relates to a hydraulic damper comprising a cylinder having an end wall, a piston rod extending through the end wall, and a ball bearing assembly mounted in said end wall for supporting said piston rod.
The various aspects of the present invention will be more fully understood when the following portions of the specification are read in conjunction with the accompanying drawings wherein:
REFERENCES:
patent: 3604725 (1971-09-01), Goff
patent: 4076225 (1978-02-01), Houghton
patent: 4306638 (1981-12-01), Malott
patent: 4768627 (1988-09-01), Taylor
patent: 4815574 (1989-03-01), Taylor et al.
patent: 5120200 (1992-06-01), Cater, III
patent: 5133435 (1992-07-01), Taylor
patent: 5159997 (1992-11-01), Heideman et al.
patent: 5487454 (1996-01-01), Klembczyk et al.
patent: 5727663 (1998-03-01), Taylor
patent: 6035740 (2000-03-01), Budaker et al.
Gastel Joseph P.
Kramer Devon
Oberleitner Robert J.
Tayco Developments, Inc.
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