US2171484A - Filtering device - Google Patents

Description

Aug. 29, 1939. A. E. SQUIRE 2,171,484

EILTERING DEVICE Filed July 1, 1937 I/mf/y 706. 56 (ya/e5 Patented Aug. 29, 1939 1 UNITED STATES PATENT OFFICE Application July 1, 1937, Serial No. 151,538 In Great Britain December 17, 1936 4 Claims.

The present invention relates to improvements in or relating to filtering means.

One well known form of filtering device consists of a conical member of suitable fluid-perme- 5 able material, for example paper, such member being formed by folding a circular piece of the permeable material, about a diametrical line so as to double the material and then folding the folded material again about a line at right angles to the first folding line so as to obtain four thicknesses or plies of material, the plies then being separated so that a cone is formed of which one half consists of a single thickness and the other half consists of three thicknesses. The so formed filter is then inserted in a funnel or other suitable support.

Various disadvantages are associated with the above mentioned filters. Thus in such devices a large amount of the material employed, i. e., two

of the three thicknesses forming one half of the cone, serve no useful purpose and indeed these additional plies introduce objections not only on the ground that they render the permeability non-uniform but also on the ground that they 5 reduce the total permeability of the filter.

One of the objects of the present invention is to provide filtering means which are simple and inexpensive to manufacture.

Another object is to provide filtering means 30 having a uniform degree of permeability over substantially the whole of their operative surfaces.

Yet another object is to provide a filtering device which can be made from a quantity of filter 35 paper or the like smaller than that previously necessary for making a filter of the same capacity.

With the above and other objects in view the present invention resides in filtering means as 40 hereinafter described and as defined in the appended claims.

Filtering means according to the present invention comprise a sheet of filtering material having edge portions brought together in over- 45 lapping or abutting relationship to provide a conical structure and secured together in any suitable manner, for instance by means of adhesive or by stitching said edge portions together or by crimping, embossing, perforating or otherwise de- 50 forming them.

The present invention also resides in a method of making a filtering device which includes the steps of bending or folding a sheet of suitable material so that it assumes or can be caused to 55 assume the form of a conical cup and then securing the abutting or overlapping portions of said sheet in any suitable manner, for instance by means of adhesive, by stitching said parts together, or by crimping, perforating, embossing or otherwise deforming said parts. 5

Preferably the aforesaid abutting or overlapping portions are secured together in such relationship that surfaces of the edge portions which are on the same side of the unfolded sheet of material contact with one another. The edge 10 portions so brought together and secured to one another are then preferably folded so that they lie against the outer surface of the conical structure, this step being of particular advantage where the said portions are secured together by 15 stitches or by a crimping or other operation which involves the perforating of the said portions since the perforations will become covered by the side of the conical structure and be effectively sealed against leakage. The said folding of the edge 20 portions moreover enables the conical structure to fit snugly into a filter funnel.

The aforesaid sheet may be of substantially semi-circular shape which may if desired have a flange along the length of the diametrical edge, the said edge or the flange where this is provided being doubled on itself and secured in such doubled relation by any suitable operation.

In order that the invention may be well understood I will now describe some embodiments thereof by way of examples and with reference to the accompanying drawing in which:

Figure 1 shows an unfolded piece of filter paper, Figures 2 and 3 show intermediate stages in the formation of the filtering device,

Figure 4 shows a perspective view of the finished device, and

Figures 5 and 6 show modified modes of securing together the overlapping parts of the device. 1

Referring to Figures 1 to 4 of the drawing, the filter device is made from a sheet of filter paper I of semi-circular form with a flange or extension 2 along its diametrical line 3. This sheet is folded about the radial line 4 so that the two halves of the paper are superimposed as shown in Figure 2. The over-lapping parts of the flange or extension 2 are then secured together for instance with the aid of a crimping or like machine forming two rows of depressions 5, 5.

The folded flange or projection 2 is then folded about the line 3 so that the crimped portion abuts against the body of the filter as shown in Figure 3. If desired the step of folding the flange may be automatically eifected by an attachment fitted to the crimping machine.

The filter papers can be conveniently stacked in collapsed condition as shown in Figure 3 and can be easily expanded, as shown in Figure 4, for use when required.

It will be readily appreciated from the form of the sheet I and the mode of folding such sheet that the possibility of any material escaping past the apex of the cone or through the over-lapping parts of the material without being filtered is prevented and at the same time the amount of material employed in the manufacture of the filter is greatly reduced as compared with'that required for the usual form of filter papers and the permeability is uniform over substantially the Whole area of the paper;

The above described embodiment of the present invention includes two rows of indentations serving to secure together the overlapping parts of the extension 2 and'these rows are located nearer to the edge of said flange than to the folding line 3. It is to be understood however that the particular position of such rows may be varied as also may be the number of rows. Thus for example Figure 5 shows a modification in which a single series of depressions 6 is formed, such depressions however being preferably a little longer than those shown. in Figures 2 and 3 in order to ensure the security of the assembled device.

Moreover it is to be understood that the doubled-flange need not necessarily be secured by a crimping, or embossing operation but may be subjected to any other suitable treatment. Thus for instance in some cases the overlapping portions of the flange may be secured together by means of adhesive and in other cases by means of stitches 1 as shown in Figure 6, the preferable mode of securing in some cases being determined by the nature of the filtering material and the use for which the filter is required.

Whilst I have hereinbefore described some examples of my invention I wish it to be understood that there may be various other embodiments falling within the scope of the appended claims. Thus for example the devices may be made of any desiredshape and dimensions, any suitable material maybe employed from which to form such devices and in some cases the filter may be made from two or more sheets of superimposed material.

I claim:

I. A method of forming a filtering device comprising taking a sheet of filter paper of substantially semicircular shape with a flange projecting along its diametrical line, folding said sheet about a radial line perpendicular to said diametrical line so as to form two quadrants ofa circle, securing together the superimposed parts of said projecting flange portion, folding said secured flange portions about said diametrical line and then opening said two quadrants to form a conical structure.

- 2. A method of forming a filtering device comprising taking a sheet of filter paper of substantially semicircular form with a flange projecting along its diametrical line, folding said sheet about a radial line perpendicular to said diametrical line so as to form two superimposed quadrants and flange portions, crimping together the superimposed parts of said flange portion in a row spaced from said diametrical line and folding said flange portion about said diametrical line back on to folded sheet whereby to form a device which upon opening out forms a conical structure. r

3. A filter device comprising a sectorially shaped sheet of filter paper having flangedike projections extending along the subtending radii thereof, said sheet being folded symmetrically about a'bisecting radius and the superimposed flange-like projections being secured together and then folded back upon the body of the sheet j along the radius formed by said superimposed subtending radii. 7

l. A filter device comprising a s'ectorially shapedsheet of filter paper having flange-like projections extending along the subtending radii thereof, said sheet being folded symmetrically about a bisecting radius and the superimposed flange-like projections being secured together by a crimped line, said crimped line being spaced outwardly from said superimposed subtending radii and-the flange-like portion being folded back upon the body of the sheet about said superimposed subtending radii.

I ALFRED-EUSTACE- SQU'IRE.

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