US2008560A

US2008560A - Air filter medium

Info

Publication number: US2008560A
Application number: US649241A
Authority: US
Inventors: Nutting Arthur
Original assignee: American Air Filter Co Inc
Current assignee: American Air Filter Co Inc
Priority date: 1932-12-29
Filing date: 1932-12-29
Publication date: 1935-07-16
Anticipated expiration: 1952-07-16

Description

July 16, 1935. A. NUTTING 2,308,560

AIR FILTER MEDIUM Filed Dec.- 29, 1952 Fig. 1 24 Fig. 3

INVENTOR. Arthur" Nufiing mam ATTORNEY Patented July 16, 1935 UNITED STATES PATENT OFFICE AIR FILTER MEDIUM Application December 29, 1932, Serial No.649,241

5 Claims.

' This invention relates to air filter mediums and proposes certain novel improvements in filter mediums 'of the flat, blanket or pad type and particularly those fabricated by winding long strands of wire around spaced sup-' ports progressively from one end of the supports to the other. With filters of this type means are usually provided for holding the strands in their original positions so as to preserve'the uniform distribution of the strands and thereby prevent their separation and the consequent impairment of the filtering density provided by the pad as a whole.

The principal object of this invention is to provide a construction of this character in which the strands are arranged in a manner such that they cooperate to hold each other and thereby eliminate the necessity of special holding means.

Another object is to provide a pad of this general type which can be so cheaply manufactured as to render its replacement after a normal period of use economically feasible.

The invention is illustrated in the accompanying drawing wherein:

Figure l is a front elevation of a pad which is partly broken in order to bring out more clearly the relation of the various elements making up the pad;

Figure 2 is a section along line 22 of Figure l; and

Figure 3 is a front elevation of an alternative construction.

In carrying out my invention I utilize a strand of material having a hard, roughened or jagged surface, the sharp protuberances or iags of which are rigid. Steel wool is a particularly suitable material, not only because of its surface roughness and low cost, but also because it can now be obtained in standard rolls, a form which facilitates the fabrication of the filter medium into a blanket or pad. Any suitable method of winding or otherwise arranging the strands to form the pad can be utilized. In a construction of the character shown in Figures 1 and 2, this is usually done by winding the strands of steel wool around opposite sides of a supporting frame -I progressively from one end of the frame to the other. This results in the formation of separate layers 2 extending acrosswopposed faces of the frame I. The filtering density provided by these layers can be controlled or regulated during the winding by controlling the spacing of adjacent strands where one strand thickness is" desired, or, by building up the thickness of the layers where more than one strand thickness is wanted. Naturally the distribution of the strands will be made uniform in order'to provide a uniform filtering density.

Now in accordance with my invention another set of layers 3 are similarly wound over the frame I in a manner such that the strands of these layers extend at an angle to the strands of the layers 2 with which they contact. With a rectangular frame as shown, this is most easily accomplished by winding the layers 3 over the other two opposed sides of the frame I so that the strands of the layers 3 extend at right angles to, and in engagement with, the strands of the layers 2. With this arrangement I have discovered that the strands of the separate layers, by virtue of their rigid jags, interlock so effectively and firmly as to hold'each other in their original or wound positions and thereby firmly preserve or maintain the uniformity of the filtering density provided by them. In other words the strands of one layer mutually cooperate by surface contact with the cross strands of the other layers to prevent the separation which might otherwise occur as a result of the handling and vibration to which they are subjected during manufacture, shipment and use. It may be noted that the interlocking effect of the strands is so pronounced that it is unnecessary to provide means for holding the free ends of the strands. Furthermore, the interlocking effect is. substantial enough to permit the cleaning of the pads, either by vibration where a dry pad is utilized, or, by soaking in oil where a pad of the viscous impingement type is used.

In Figure 3 apad of this general type which is less expensive to manufacture, is shown. In this construction the arrangement of the layers 2 and 3 is the same as that of Figures 1 and 2 but the use of a supportingframe eliminated. In the construction shown in Figures 1 and 2 the sup- 40 porting frame maintains the pad in a flat condition. In order to maintain the pad of Figure 3 ina fiat condition it is welded at intervals as indicated at 4, the welded portions extending at an angle to the strands of the outside layer. These welded portions furthermore are made short and widely separated dn order to prevent curling or waving of the marginal edges of the strands, a condition which would result from a continuous line weld. Such condition is undesirable because it prevents the accurate fitting of the pad as a whole into the outside filter frame ordinarily provided. This latterconstruction is particularly intended for insertion into a frame composed of a material, such as card-board, so

that the entire filter can be disposed of by buming after a normal period of use. In this connection it may be noted that the strands of steel wool ordinarily used for filtering purposes are so thin that they will readily burn when fire is applied.

Having described my invention I claim:

1. A filter pad having at least two mutually engaging layers of stranded metallic material arranged so that the strands of one layer extend at an angle to the strands of the other layer, the strands of both layers presenting a jagged surface having rigid jags by virtue of which the crossed strands interlock with each other at the points of contact.

2. A filter pad having asupporting frame, a layer of stranded metallic material having a jagged surface wound over said frame with the strands extending in parallel relation, the jags of said surface being rigid, and another layer of similar material similarly wound over said frame with its strands extending at an angle to and in surface interlocking contact with the strands ofthe first layer.

3. A filter pad having a rectangular supporting frame, a layer of stranded material having a jagged surface wound over two opposed sides of said frame progressively from one end to the other with the strands extending in parallel relation, the Jags of said surface being rigid, and another layer of similar material similarly wound over said frame with its strands extending at right angles to and in surface interlocking contact with the strands of the first layer.

4. A filter pad having at least two mutually engaging layers of material in the form of wire strands arranged so that the strands of one layer extend at an angle to the strands of the other layer, the strands of both layers presenting a jagged surface having rigid jags by virtue of which the cross strands interlock with each other at the points of contact, and means for holding said layers in a fiat condition, said means consisting .of a series of short welds substantially spaced from each other.

5. A filter pad having an inner layer of stranded metallic material, and an outer layer of similar material wound over said inner layer, the strands of one layer extending at an angle to the strands of the other layer and the strands of both layers presenting a jagged surface having rigid lags by virtue of which the crossed strands interlock with each other at the point of contact.

ARTHUR NU'ITING.