Motors: expansible chamber type – Working member position responsive motive fluid control
Reexamination Certificate
2000-04-12
2001-09-04
Look, Edward K. (Department: 3745)
Motors: expansible chamber type
Working member position responsive motive fluid control
C091S405000
Reexamination Certificate
active
06283008
ABSTRACT:
The invention relates to a shockproof hydraulic cylinder that has
a) a cylinder housing, in which a plunger that is connected to a plunger shaft is arranged to move axially, and
b) an annular cylinder chamber, defined by the inner surface of the cylinder housing, the outer surface of the plunger shaft, the bottom side of the plunger shaft guide of the cylinder head and the top side of the plunger,
c) whereby in its lower area, the plunger shaft has at least one opening that connects the outside of the plunger shaft to a hydraulic medium reservoir and that is sealed by the plunger shaft guide of the cylinder head shortly before the upper plunger end position is reached.
Such hydraulic cylinders are used as, i.a., lifting cylinders for industrial trucks. From DE-OS 36 06 515 is known a hydraulic cylinder that is shockproof, but that consists of only a simple hydraulic arrangement. The transport of sensitive items requires that lifting shocks, which under certain circumstances create loud noises and can damage sensitive cargo items, are avoided as much as possible. This cannot be achieved with the hydraulic cylinder that is known from DE-OS 36 06 515. Moreover, it is disadvantageous in the case of this hydraulic cylinder that no other consumers may be downstream from the cylinder.
The object of this invention is to indicate a hydraulic cylinder that makes possible improved shockproofing.
To achieve this object, the invention proposes that the cylinder chamber be connected to a hydraulic medium reservoir via a defined choke site.
REFERENCES:
patent: 3213760 (1965-10-01), Carr
patent: 4638717 (1987-01-01), Carr
patent: 12 93 026 (1969-04-01), None
patent: 22 54 495 (1974-05-01), None
patent: 36 06 515 (1986-08-01), None
patent: 0 622 331 (1994-11-01), None
Baerwolff Christian
Gaffke Heniz
Schonewald Peter
Lazo Thomas E.
Look Edward K.
Millen White Zelano & Branigan P.C.
Still GmbH
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