Liquid purification or separation – Filter – Supported – shaped or superimposed formed mediums
Patent
1994-05-16
1996-03-26
Dawson, Robert A.
Liquid purification or separation
Filter
Supported, shaped or superimposed formed mediums
2104935, 55497, 55521, B01D 2706
Patent
active
055017940
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND FIELD OF THE INVENTION
The invention is directed to a filter system for filtering fluids, particularly gases, particularly for filtering air streaming into the passenger cabin of a vehicle, comprising a filter element folded in a wave-shaped or zig-zag-shaped manner having bending lines and substantially plane filter element folding portions arranged therebetween, the filter element being adapted to be stretched in the direction of its successive folding portions and to be compressed in the opposite direction.
A pleated paper filter is known from French Patent No. 1,289,456, provided with longitudinal paper glued to the edge of the filter. The paper filter is maintained in the pleated zig-zag condition by a rigid peripheral framework in conjunction with longitudinal and transverse support wires. The transverse wires are attached to two parallel longitudinal-wires side edges of the filter. The transverse support wires engage the filter at the bending lines of each pleat fold maintaining the pleat structure and spacing.
Filter systems for filtering air streaming into the passenger cabin of a vehicle are known in a wide range of versions. Examples of such known filter devices are described in German Laid-open Application Nos. 25 57 444, 35 29 579, 35 34 318, 37 16 243 and 38 15 907, as well as in German Patent Specifications 21 38 412 and 34 39 255 and, finally, in German Utility Model 80 01 798. A common feature of all these filter systems resides in that the filter element is fixedly mounted in a filter frame so that exchange of the filter element is not possible without exchanging the filter frame along with it.
In known filter systems, the filter element is arranged in wave- or zig-zag-shaped folds for enlarging the filtering area. Since the filtering materials (for instance, paper or non-woven materials) have hardly any inherent stability of shape, there is either added an air-permeable reticular support structure to the filter element, or there are provided spacers for keeping the substantially plane folding portions of the filter element between successive bending lines of the filter element at mutual distances and thus maintaining said filter element folding portions in their V-shaped orientation relative to each other. The provision of spacers complicates the construction of the filter system.
The filter system known from EP 0 170 643 comprises a filter element adapted for insertion into a filter frame. The filter element is accommodated in the filter frame in a manner allowing exchange of the filter element. For providing stability of shape of the zig-zag-shaped filter element, also this known filter system includes special mutually engaging teeth on the two-part filter frame. By such teeth or spacers, not only the construction of the filter system but also the process of inserting a new filter element becomes more complicated.
It is the object of the invention to provide a filter system wherein-the filter element is automatically given stability of shape with increased stretching thereof.
For solving the above object, the invention provides a filter system of the initially mentioned type, wherein the filter element is provided with two tensioning members, which have a modulus such as to limit the stretching of the filter element and which also fix the filter element folding portions when the tensioning members are elongated under tension, and wherein the tensioning members at the two side edges of the filter element extending in stretching direction are tightly connected to the filter element.
In the filter system of the invention, the filter element is provided with a respective tensioning member on each of its two edges extending in stretching direction. This tensioning member is resistant to tensile forces and will not stretch to any noteworthy extent when subjected to tension; for instance, the tensioning member can be a flexible tensioning band resistant to tensile forces and being hardly stretchable. Typically, the tensioning member will be an inelastic, high modulus, flexible
REFERENCES:
patent: 3243943 (1966-04-01), Getzin
patent: 4042358 (1977-08-01), Frohmader
patent: 4135900 (1979-01-01), Westlin et al.
patent: 4142551 (1979-03-01), Wilms
patent: 4227953 (1980-10-01), Wasielewski et al.
patent: 4963171 (1990-10-01), Osendorf
Horsten Anton J. J.
Van de Graaf Peter
Bond William J.
Dawson Robert A.
Griswold Gary L.
Kirn Walter N.
Minnesota Mining and Manufacturing Company
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