Receptacles – High-pressure-gas tank
Reexamination Certificate
2000-07-05
2001-05-01
Pollard, Steven (Department: 3727)
Receptacles
High-pressure-gas tank
C220S565000
Reexamination Certificate
active
06223929
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a pressure-proof tank, specifically a pressure-proof tank for a transport container.
German Offenlegungsschrift 3,125,963 disclosed a pressure-proof tank which comprises an envelope formed by part-cylindrical envelope shells extending parallel to the longitudinal tank axis, the ends of the envelope being closed by bottoms formed by bottom shells. Gusset elements are disposed between the envelope and bottom shells.
The known tank is designed as a thick-walled receptacle for liquid gas as fuel for vehicle motors. The tank is made of one fully cylindrical shell and one part-cylindrical shell, with the part of the full cylinder extending through interior of the tank forming an intermediate wall, which may be flattened.
Membrane stresses in the curved tank skin caused by interior pressure lead to forces in the zones where the curved shell elements converge. These forces tend to expand the tank in a direction perpendicular to the tank axis.
A similar tank for high-volume containers with curved gusset elements, which is similarly problematic in terms of membrane stresses, is known from German patent specification 3,606,247.
SUMMARY OF THE INVENTION
It is an object of the present invention is to avoid stress problems in the transition region between the envelope shells and bottom shells, especially in high-volume tanks.
This object is met in accordance with the invention by a pressure-proof tank defining a longitudinal tank axis and comprising an envelope having ends and being formed by part-cylindrical envelope shells extending parallel to the tank axis, bottoms closing the ends and being formed by bottom shells defining bottom shell axes perpendicular to the tank axis, curved gusset elements disposed between the envelope shells and the bottom shells, and a pair of planar rib elements extending through the interior of the tank in planes transverse to the plane defined by the tank axis and the bottom shell axes, wherein the gusset elements are connected to the envelope shells through said rib elements.
In accordance with the invention, forces resulting from the membrane stresses explained above are absorbed by rib elements which extend through the tank in the direction of these forces. The rib elements are disposed between the converging envelope shells and gusset elements so that the various structural elements can be connected by fillet welds which are particularly easy to make.
The rib elements of the invention form an integral component of the tank, which ensures high pressure resistance of the entire tank, provides favourable continuous stress characteristics and acts as a damping element to counteract surge effects in both longitudinal and transverse directions.
As another advantage of the tank structure provided by the present invention, a container including the tank has a low centre of gravity as is particularly suitable for high-wheeled off-road vehicles, thereby further decreasing surge effects which tend to occur especially when the tank is only partially filled.
In a preferred embodiment, the rib elements are integrally formed by two wing portions of one bent metal sheet. This reduces the amount of welding work and the number of welded joints.
In accordance with another preferred embodiment, the tank comprises a profile element extending through the interior of the tank perpendicularly to the tank axis an welded to the rib elements. The profile element constitutes a tie rod cooperating with the rib elements to further reduce tensile forces exerted on the tank skin.
A hollow circular or Y-shaped cross-sectional shape of the profile element is advantageous in that it further avoids an accumulation of weld joints, especially in the zone where the longitudinally and diagonally extending beads formed between the envelope and bottom shells meet.
Additional reinforcement of the overall tank structure may be achieved by a planar tension wall extending through the interior of the tank in a plane containing the tank axis. The tension wall may have a portion protruding out of the tank and including a leg extending transversely of the plane of the tension wall to avoid buckling.
Preferably, the surface of the leg remote from the tank is coplanar with a plane defined by vertex lines of the envelope shells. This structure permits the bead zone formed between the envelope shells to be sealed by a flat plate. The resulting stabilised surface can serve as an operation platform or for fixing additional components in the upper tank region. In the lower region, the leg of the tension wall may serve as a support surface of the overall tank.
The rib elements are preferably welded to the tension wall or to the profile element to achieve a further stabilisation of the entire structure.
A structure which is especially favourable from the manufacturing standpoint is obtained if one of the rib elements and the tension wall are integrally formed by one metal sheet having a bend, with the other rib element being welded to the sheet along the bend.
REFERENCES:
patent: 2673001 (1954-03-01), Ulm et al.
patent: 2705349 (1955-04-01), Shaw
patent: 2818191 (1957-12-01), Arne
patent: 2975927 (1961-03-01), Arne
patent: 3112044 (1963-11-01), Larsen et al.
patent: 3314567 (1967-04-01), Becker et al.
patent: 3414153 (1968-12-01), Leroux
patent: 3645415 (1972-02-01), Phelps
patent: 3125963 A1 (1983-02-01), None
patent: 3606247 C1 (1987-05-01), None
Connolly Bove & Lodge & Hutz LLP
Pollard Steven
Wew Westerwaelder Eisenwerk GmbH
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