Liquid purification or separation – Filter – Supported – shaped or superimposed formed mediums
Patent
1990-10-31
1992-01-14
Sever, Frank
Liquid purification or separation
Filter
Supported, shaped or superimposed formed mediums
55497, 55500, 55521, B01D 2907
Patent
active
050807900
DESCRIPTION:
BRIEF SUMMARY
The invention relates to strip-shaped filter material, especially filter paper for liquid or gas filters, with crimps molded in, pursuant to the preamble of claim 1, as well as filter elements made of these materials, pursuant to the preambles of claims 7 and 10.
Crimps in filter papers have always had semi-circular cross-sections until now (for example, DE-OS [German laying-out statement] 19 30 715). With such crimps, the paper thickness is always least at the transition from the non-deformed level filter surface into the crimp, which can result in material-related filtration problems at these sites, which are under high static and dynamic stress during filter operation.
Filter elements made of strip material with crimps which is folded in zig-zags are also known, for example from DE-PS [German Patent] 12 48 618.
To the extent that filter elements with crimped filter strip materials are known beyond this, from DE-OS 19 22 976 and DE-OS 26 51 910, these do not demonstrate sufficient stability under extreme operating stress.
Proceeding from this situation, the invention is based on the task of providing crimps in the filter strip materials in such a way, and shaping them into filter elements with zig-zag-shaped folds, so that great static stability of the folds of the filter element can be achieved, while at the same time, the filter material is not damaged by the crimps.
This task is accomplished, for one thing, by the structure of the crimp shapes according to the characterizing section of claim 1, and for another thing, by the arrangement and shape of the crimps within the strip material, and its zig-zag folding to form a filter element according to the characterizing sections of claims 7, 8 and 10.
Practical developments of the invention are the object of the secondary claims.
Embodiments of the invention are shown in the drawing. The drawing shows:
FIG. 1 a cross-section through a crimp running vertical to the plane of the filter strip
FIG. 2 a top view of a part of a filter material strip
FIG. 3 a cross-section through the filter material strip along Line III--III on an enlarged scale
FIG. 4 a perspective view of a segment of a filter strip folded in zig-zag shape
FIG. 5 a view of the frontal side of a filter element folded in zig-zag shape
FIG. 6 a cross-section along Line VI--VI through the folds of the filter element according to FIG. 5
FIG. 7 a view of the frontal side of an alternative embodiment of a filter element folded in zig-zag shape
FIG. 8 a cross-section along Line VIII--VIII through the folds of the filter element according to FIG. 7
FIG. 9 a view of the frontal side of another embodiment of a filter element folded in zig-zag shape
FIG. 10 a cross-section along Line X--X through the folds of the filter element according to FIG. 9
In the crimp shown in cross-section in FIG. 1, the progression of the funicular curve, which determines the shape of the curvature of the crimp in this case, is entered with a dot-dash line.
A funicular curve is a mathematical concept and is defined by the progression of a chain with an infinite number of links, under the stress of its own weight. Such a funicular curve is also called a catenary curve, in some instances.
By adapting the curvature of the crimp to the progression of a funicular curve, a significant increase in inherent stability is achieved, as compared with known crimp shapes.
In FIG. 1, H stands for the crimp height, B for the crimp width and D for the filter paper thickness.
In the embodiment according to FIG. 1, the filter material has a thickness, in cross-sections placed perpendicular to the strip plane, which constantly decreases within the area of the crimps, starting from the non-deformed filter strip segments, to the zenith height H of the crimp, with the filter material being compressed in the direction of decreasing thickness.
In this embodiment, a dimensional reduction in thickness in the direction of the zenith height H of the crimp also exists perpendicular to the filter strip plane of a cross-sectional plane placed through a crimp.
REFERENCES:
patent: 3062378 (1962-11-01), Briggs
Knecht Filterwerke GmbH
Sever Frank
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