Pipes and tubular conduits – With pressure compensators – Variable capacity chambers
Reexamination Certificate
2000-07-27
2001-12-25
Hook, James (Department: 3752)
Pipes and tubular conduits
With pressure compensators
Variable capacity chambers
C138S030000
Reexamination Certificate
active
06332477
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a piston-type accumulator for a hydraulic fluid to be supplied to a consumer in a hydraulic installation, especially for hydraulic actuation of the discharge unit in the case of non-automotive vehicles for bulk commodities. A piston is mounted movably in a cylinder, dividing the cylinder into an oil chamber and a gas chamber. Connections are provided on the oil chamber for the supply of the loading fluid stream and discharge of the working fluid stream. An axially movable tappet is in the cylinder, cooperates with the piston with its inner end, and is guided with its outer end in the cylinder cover limiting the gas chamber. A control valve serves as shut-off device for the loading fluid stream, can be actuated by a bypassing conduit. The bypassing circuit is optionally connected or disconnected, for bridging of the piston-type accumulator with the connection for the loading fluid stream connected to the oil chamber. The outer end of the tappet is guided in a sealed manner through the cylinder cover to the outside, is accessible on the external surface of the cylinder as an operating member for the control valve, and forms a structural unit which can be mounted detachably on the outside of the cylinder cover.
BACKGROUND OF THE INVENTION
DE 91 13 007 U1 discloses a piston-type accumulator for the actuation of the bulk material discharge device in railway cars. The hydraulic installation provided for such railway cars has at least one hydraulic pump driven by an additional driving wheel set arrangement, which pumps a loading fluid stream into the piston-type accumulator during movement of the railway car. If the adjusted operation pressure is then attained in the accumulator in this manner, the shut-off device causes the loading fluid stream to be reversed in direction to pass through the bypassing conduit without pressure to the reservoir connection of the hydraulic installation. Therefore, the stream flows back into the fluid storage container.
With that piston-type accumulator, the combination of the traditional pressure accumulator and the shut-off device for the loading fluid stream with the required associated operating device leads to a costly structure, producing excessively high manufacturing and maintenance costs. The plurality of structural component parts which are movable relative to one another increases the wear on parts.
DE-A-1 185 025 discloses a piston-type accumulator for the actuation of the bulk commodities discharge device on railway cars. The hydraulic installation provided with such railway cars has at least one hydraulic pump powered by an additional set of wheels. The pump pumps a loading fluid stream into the piston-type accumulator during the movement of the railway car. If the adjusted operation pressure is then attained in the accumulator in this manner, the shut-off device causes the loading fluid stream to be reversed through the bypassing conduit without pressure to the reservoir connection of the hydraulic installation and to flow in reverse into the fluid storage reservoir.
SUMMARY OF THE INVENTION
Objects of the present invention are to provide a piston-type accumulator having a compact structure and a particularly favorable operational behavior.
In the case of a piston-type accumulator, the objects are attained according to the present invention by the inner end of the tappet, provided for cooperation with the piston, being guided longitudinally slidably in a traverse found in the gas chamber and fastened to the inner wall of the cylinder.
This inner guiding arrangement allows for the development of the part of the cylinder defining the gas chamber to a considerable structural length, providing considerable volume in the gas chamber within the piston-type accumulator as compared with the lifting volume of the piston in the oil chamber. This arrangement is particularly advantageous in that the pressure differential, despite the compact structure of the accumulator, is generated over the entire working or power stroke of the piston and remains quite small. Favorably, safe operation of the hydraulic installation is provided, including the special case of the bulk commodity discharge device.
Other objects, advantages and salient features of the present invention will become apparent form the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.
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Baltes Herbert
Scholl Josef
Hook James
Hydac Technology GmbH
Roylance Abrams Berdo & Goodman L.L.P.
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