US 2463722 A
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March 8, 1949. L. SPRARAGEN 2,463,722
- AIR FILTER 5 Sheets-Sheet 1 Filed June 15, 1944 INVENTOR LauzwJ/Jrmu en, BY r ATTORNEYS March 8, 1949. L. SPRARAGEN r 2,463,722
AIR FILTER Filed June 15, 1944 s Sheets-Sheet 2 HEJVENTOR lows 529761211 871,, BY
ATTORNEYS March 8, 1949. SPRARAGEN 2,463,722
AIR FILTER Filed June 15, 1944 v .3 Sheets-Sheet 3 Fly. 72 g "In-:- YIIIIIIIII/IIIIII/IIIIIIIIIIIIIIIIQ VIIIIW/IIIIfl/IIIII IIIIIIII/I ngvENToR 04m" ,Jwamgeh,
ATTORNEYS Patented Mar. 8, 1949 UNITED STATES PATENT OFFICE AIR FILTER Louis Spraragen, Bridgeport, Conn.
Application June 15, 1944, Serial No. 540,441
1 Claim. 1
This invention relates to air filters, and more particularly to a filtering unit attachable to airsucking equipment such as pumps, internal combustion engines and the like to purify air being used by same.
Filters commonly used for this general purpose have screening elements which in some cases are made of woven or felt cloth, and in other cases are in the form of sponge-like pads made of metallic ribbon. In purifying air, the latter type are generally coated with a non-drying or viscous dust-collecting substance such as oil, whereas the cloth elements are usually operated dry, and depend on the closeness of the weave and the fibrous character of the material for cleaning the air.
In the case of filters employing metallic pads, the elements are formed by severing a predetermined amount of material from a large supply, and shaping the material usually into the form of an annulus, for insertion into a supporting housing. When this is done, the interstices of the material, which originally are not too uniform in size and shape due to the lack of resilience of the metallic ribbon and due to handling, are further deformed so that a considerable diverging exists when the element is finally resting in the filter. Moreover, at the point where the ends of the element meet, in an annulus, large irregular spaces are created, a condition which cannot be readily corrected.
As a result, incompletely filtered air is permitted to enter the equipment through the large openings and interstices of the irregular pad structure, and may under severe and adverse atmospheric conditions cause considerable damage.
Textile cloth or fabric filter elements generally obviate this condition, but are more costly to make, requiring especially constructed supporting structures and more expensive assembly operations. Also, the elements may not be readily cleaned, so that when they become dirty replacement with new elements is necessary. Whereas cleaning of the metallic sponge element of air filters may be accomplished in a simple manner by merely dipping them into a solvent and recoating with fresh oil. This procedure would cause sagging and deterioration of the material if applied to a textile fabric air-filter element. Also, with textile fabric there is the likelihood of tearing or unraveling, which would defeat the purpose of the filter.
It is an object of the present invention to obviate the above disadvantages in filters. This is accomplished by the provision of a filtering unit having comparatively rigid self-supporting screening elements which are non-deteriorating and provide numerous interstices substantially uniform in size and shape and also provide fibrous tendrils extending about and into the interstices to intercept and facilitate the collecting of foreign matter from the incoming air.
Due to the absence of inadvertent large openings either at or between junctures of the screening material, the cleaning of the air is accomplished uniformly and by the use of fibrous tendrils the dirt collecting surfaces and areas are greatly increased, and the filtering action generally improved.
The filter or screening elements may be used in a dry condition to filter air, or may be coated with a non-drying viscous substance such as oil, depending on requirements, and in either case cleaning of the elements may be carried out without detriment thereto by employing a simple rinsing procedure. The interstices of the elements may be accurately controlled as to size and uniformity, may be made small or large to suit particular conditions, and the elements themselves may be conveniently formed and interfitted if desired to provide consecutive screenings of the air.
In one form of the invention, the filter elements comprise formed pieces of wire mesh, the wires of which at their points of contact are bound together by cement, the mesh havin a uniform coating of flock also secured by cement and arranged so that the fibers thereof extend from the wires in all directions. According to this arrangement the use of pieces of pliable textile fabric in a filter, with their accompanying disadvantages, is not necessary.
In an illustrated embodiment of this invention, the construction of the unit provides two such flocked elements, each cylindrical, one of larger diameter than the other, which are concentrically mounted in a housing, and a third element is zigzag folded so that when the ends are connected it forms a multi-pointed star which may be disposed between the two cylindrical elements.
In another illustrated form of the invention a. plurality of cylindrical concentrically disposed elements is carried in a holder.
In each of these constructions the air may pass through the elements consecutively, the outer one first.
According to the present invention rigid screening elements may be woven or molded plastic screening, formed of Vinylite or other plastic material, or may be made of expanded metal or paper, formed papier-mach, and the like, with the flock coating secured to the screen through the use of adhesives suitable to each particular material.
The end of the screen elements may be bound with a soft textile fabric so as to seal the same and housing plates between which the screen elements are located. Or a felt strip may be interwoven in the mesh, when the elements arebeing made so that when the mesh is cut to divide the felt strip, the cut edges of the mesh have felt edging which functions as a gasket at the points where the filter housing engages the edge of the screens. Also, the surfaces of the housing which engage and support the elements may-be heavily coated with a yieldable material into which the edges of the mesh may be embedded, to provide an air-tight connection.
A novel supporting or housing structure provides for quick and convenient removal of the elements for cleaning purposes, yet prevents leakage past co-engaging surfaces. By this construction replacement of' the elements may be quickly accomplished also.
Other features and advantages will hereinafter appear.
In-the accompanying drawings- Figure 1 is a top view of a filtering unit made according to the invention, with the top plate of the housing removed.
.Fig, 2 is an axial section .taken on the line -2--2 .of Fig. lgparts of the screens being shown diagrammatically.
Fig. 3 is aperspective viewof the central supportingwtube .of the unit.
Fig. .4 is a perspective view of the top closure .forthe tube.
Fig. .5 is a-perspective view of .an end plate carrier for the star-.shaped'filter element.
Fig-6- is .a fragmentary elevational detail of the filter mesh construction, showing the largemesh employedin the outer cylindrical ,elementof the filtering tunit.
Pier-7 is similar to Fig; 6,.butshows the smaller mesh employedinthe inner-cylindrical element of the unit.
.Fig. 8is-aperspective view of the .zigzag folded mesh .for the star-shaped .intermediate element. before beingexpanded andformed to finalshape.
Fig.9 is an enlarged fragmentary sectional view .of a folded edge of an element made according tozthe invention.
.Fig. 10 is atop view'of amodified form .of filtering unit, with the top-plate of the housing removed.
Fig. 11 is a top view of another modified form of filteringunit, top housing plate removed.
Fig. 12 is a side elevation, partly in section, of
vanother modified form of .filtering unit, for .mounting with its axis horizontal.
Fig. 13 is atransverse section taken on theline .|3l3 of Fig. 12.
Fig. 1.4.is. a transverse section taken on the line M-l 4 ofFig. .12.
The filtering .unit shown in Figs. 1 through 9,
which may be advantageously used to filter intake air for the carburetors of internal combustion engines, for pumps and the like, has a housing comprising. a central tubular stem 20 which carries circular bottom and top plates 2| and 22, respectively. The bottom plate 2] has an upturned central flan e 2la which snugly fits the outside diameter of the stem 20 and is spot Welded I thereto as indicated in Fig. 2.
The-top end of the stem "2ll-is provided with a formed sheet metal closure 23 which fits snugly inside the stem and is also spot welded thereto (Fig. 2). The closure 23 is at its center extruded and threaded to carry a stud 24 extending through the center of the top plate 22, a winged nut 25 being provided for demountably securing the top plate to the stern.
According to the invention the bottom and top plates '2! and 22 are shaped to carry the selfsupporting filtering elements of the unit, and for this purpose as shown in Fig. 2 the peripheral edges of the plates have flanges 2H; and 22a respectively, extending toward each other. Carried between the top and bottom plates in engagement 0 with the flanges 2 lb and 22a is a novel comparatively rigidself-supporting filtering element 26. This element is of wire mesh having a coating of flock disposed on it in such a manner that the fibers thereof extend in all directions from the wires. forming dirt-collecting tendrils which effectively filter and clean air which may pass through the element. The flock may be deposited on the mesh by being blown against it, and made to adhere to the wires by a suitable adhesive or cement, whichmay also bind the wires themselves where they cross. As shown in Fig. 1 the flocked mesh is formed into a cylinder which fits closely inside and against the flanges Zlb and 22a of the top and bottom plates. the joining edges of the cylinder being secured by a clamp strip 26a having lanced fingers 28b which pass through the interstices ,of the mesh and are folded over on the latter at the inside. The filtering element 26 as thus constructed is substantially rigid so that it may be firmly held between the top and bottom plates of the filtering unit by drawing these plates together by means of the winged nut 25. Due to the engagement of the flanges 21b and 22a with the filtering element 26 at the open ends thereof,
.: a seal is effected so that the likelihood of air by passing the element at its edges Without being filtered is minimized.
A second self-supporting cylindrical filtering element 21 located closely adjacent and concentric with the stem 20 is also provided. The element 2! is coated with flock substantially in the same manner as the cylindrical element Ziiand has a diameter to fit closely around the central flange Zia of the bottom plate. For the purpose of centralizing it at the top plate, the latter is embossed to provide a downwardly dished center portion 22b closely fitting inside the upper end .of the element 21. The meeting ends of the element 21 are joined in a, manner similar to that used for the element 25, by a clamp strip 270. having lanced fingers 21b, as shown in Fig. l.
The invention also provides another noveland self-supporting filtering element 28 in the form of a multi-pointed star which is disposed between the elements 26 and 2.1 to provide somewhat of a tortuous path for the air passing through the filter unit. The element 28 is of flocked mesh, being shaped by initially zigzag folding it into a pack as shown in Fig. 8, in which form it may be conveniently handled for shipment, replacement, etc. The detail shown in Fig. 9 illustrates the bending of the mesh, as at one of the points of the star. For supporting the star-shaped element 28, a pair of identical spacer rings 29 and 3B] are provided, one such ring being illustrated in Fig. 5. Referring to Fig. 2, the bottom and top plates 2i and 22 of the filter have embossed circular beads Mo and 220 respectively, adapted to engage and centralize the spacing rings '29 and 3B, the latter having cylindrical fianges'ZSa and 30a respectively, engaging the inner bends of the star, and also having pluralities of fingers 29b and 38b which are lanced from the rings for clamping selected bends of the star to the flanges. As shown in Fig. 1, the meeting ends of the element 28 are overlapped in the manner indicated.
Preferably the star-shaped element 28 is provided with'cloth binding strips 28a and 281) which are folded over the bottom and top edges respectively. These strips, which may be cemented in place to securely hold them, may function as gaskets in engaging the inner surfaces of the top and bottom plates to prevent the passage of air at these points.
The filtering unit is adapted to be mounted on an air intake pipe by means of the stem 20, the air supply to flow through the bore of the stem. As shown in Figs. 2 and 3, for this latter purpose the walls of the stem 2|] are cut away to provide a pair of oppositely located enlongate slots a. and 261) which open into the interior of the element 21.
By this construction suction applied to the stem 20 will cause air to be sucked through the elements 26, 28 and 21 consecutively in the order given. As is often customary in air filters, the elements may be coated with a viscous non-drying substance such as lubricating oil, so that the dust-collecting action of the flock is enhanced. According to the invention by the provision of the upturned flanges 21a and 2lb on the lower plate 2!, the latter may carry a quantity of oil when the filtering unit is mounted with its axis vertical, this oil traveling by capillary attraction up the elements 26, 21 and 28 and maintaining a dirt-trapping coating or film on the flock. Preferably the size of the mesh of the element 26, pictured in Fig. 6, is larger than that of the element 28, and the latter in turn larger than that of the element 21, pictured in Fig. 7, as an example, the element 26 may be ten mesh, the element 28 fourteen mesh, and the element 21 sixteen mesh. This is advantageous since the speed of the air flow through the element 26 is slower than through the element 28, and the speed through the element 21 faster than through the element 28.
The filter elements 26, 21 and 28 being comparatively rigid, will be adequately supported by the respective associated parts of the housing of the unit, and will not loosen if the unit is subjected to vibrations not greatly in excess of those normally encountered. In connection with this, the reinforcement provided by the cementitious binder at the points where the wires of the mesh cross each other contributes to the mechanical stability and strength.
If, as a result of damage, or clogging of the mesh due to long continued use, it is desired to remove the elements, this may be quickly and conveniently accomplished by loosening the winged nut and removing the top plate 22. The elements may then be easily lifted out and either cleaned by dipping in cleaning solution, or replaced with new.
If the filter is to be used where it is desirable to have an oil or other viscous coating on the elements, the nature of the cement or adhesive used to secure the flock to the wire should be such that it will not be affected by this coating, nor the cleaning solution employed to remove the coating in cleaning the element.
A modified form of the invention is shown in Fig. 10. According to this form'a single selfsupporting filtering element 3| of flocked mesh shaped like a multi-pointed star is mounted between the plates 21 and 22 so that the points of the star engage and are positioned by the flanges 2Ib and 22a. Preferably the top and bottom edges of the mesh of the element 3| are provided with folded cloth binding strips, as in the case of the element 28, to act as gaskets and prevent by-pass of air without filtering.
By forming the element 3| in the shape of a multi-pointed star, a large surface area is presented for the passage of air, so that the speed of flow is reduced, thereby resulting in a more effective removal of dust, dirt, etc.
In another modified form of the invention, shown in Fig. 11, a plurality of concentric cylindrical flock-coated mesh filtering elements 32, 33, 34 and 35 are provided, nested one within another. The outermost element 32 fits closely within the peripheral flanges of the top and bottom plates, the latter only, designated by the character 36, being shown, with flange 36a.
For spacing the elements in concentric positions, the bottom and top plates are embossed to provide knobs 31 which are located as shown,
' engaging the edge portions of the elements and preventing movement of same.
The meeting edges of the cylindrically formed mesh elements are secured together by folding to form interlocked seams 38 which prevent bypass of air along these edges.
Due to the elements having surface areas which are graduated, the speed of air flow through the respective elements is also graduated, and preferably the size of mesh is chosen accordingly, the outermost element having the largest mesh, and the innermost the smallest.
Also, preferably the end portions of the cylindrical elements are provided with folded cloth binding strips which engage the end plates and function as gaskets.
An air filtering unit adapted for mounting with its axis horizontal is shown in Figs. 12, 13 and 14.
As shown, a housing isprovided comprising a pair of circular substantially parallel end plates 39 and 40, the plates having inwardly extending peripheral flanges 33a and 48a, and central inwardly dished portions 3% and 48b respectively.
Each plate is centrally apertured to receive a bolt 4! which, by means of a nut 42, holds the end plates from separating.
A self-supporting cylindrical flocked mesh filtering element 43 is mounted between the plates 38 and 40, the ends of the element fitting closely about the dished portions 3% and b for positioning thereby. Engaging the exterior surfaces of the flanges 39a and 48a is a self-supporting semi-cylindrical flocked mesh element 44, the two straight edges 44a of which (Figs. 13 and 14) are clamped between folded straight edges 45 of a concavo-convex mounting plate 46 which latter also engages the outside surfaces of the flanges and complements the element so that together they form a complete cylinder.
The filtering element 44 and plate 46 are securely clamped to the end-plates 38 and 40 by bands 41 and 48 which may be tightened by bolts 49, as shown in Fig. 12.
In addition to the cylindrical filtering elements 43 and 44, a self-supporting star-shaped fllocked mesh element 50 is mounted between the end plates, the straight edges 50a of the element being hooked under the folded inturned edges 45 of the mounting plate.
Referring to Fig. 12, the inner surface of the end plate .39 is covered 'or coated with a yielding substance 3390 such as rubber, the synthetic Thiokol being for instance suitable, so that when the-filtering elements are properly positioned and the end plates 39 and 40 drawn together by the bolt 4|, prior to finally tightening the bands 41 and 48, the edge of the star element 50 will be embedded in the rubber and the latter will function as a seal toprevent by-pass of air.
. An-alternative structure for accomplishing the same result is also shown in Fig. 12, in connection With the end plate 40. A strip of felt is interwoven in the edge of the element 50, so that when the plate 40 is held against the edge the felt will be engaged and seal all openings.
In making up the element 50 for use with felt sealing strips, the mesh might be fabricated in large widths with a wide strip of felt interwoven at regular intervals, and the elements then formed by cutting the mesh along the center lines of the felt strips, so that each edge formed by the cut would have an interwoven felt strip.
In assembling, when the elements 4-3, M and 50 have been mounted between the end plates 39 and 40, the tie bolt 4| is tightened to draw together the plates, which thereby clamp the elements 43 and 50 between them. The bands 47 and 48 are then tightened, securely clamping the mounting plate 46 and element M to the end plates.
For the purpose of supporting the filter unit on an air intake pipe of a carburetor or the like, a tubular stem 52 is provided passing radially through the center of the mounting plate 49, which is formed to receive it, and into the cylindrical element 43, the stem being rigidly fastened to the plate. As shown in Fig. 13, the mesh of the element 43 is formed to fit closely to the outside of the stem 52, and may be welded or otherwise fastened to the latter.
The connections between the end plates 39, 40 and the mounting plate 46, and between the latter and the stem 53 are preferably leak-proof so that oil or other viscous liquid may be placed inside the mounting plate to mount by capillary attraction on the filtering element 50.
The self-supporting flock-coated filtering grids of the present invention may be formed of stamped sheet metal, perforated paper, or of wire mesh both metallic or non-metallic. With re gard to the latter the mesh may be made of wires of Vinylite or other suitable plastic. Or the grids may be made of expanded metal, expanded paper, papier-mach and the like, depending on the use, in each case the adhesive for securing the flock to the grid being chosen with particular reference to the grid material.
Where comparatively soft materials are used in constructing the filtering grid, the portions of the latter which engage the end plates may de- Number form slightly when the plates are drawn together, and conform closely to the plate surfaces, making gaskets unnecessary.
Variations and modifications may be made within the scope of this invention and portions of the improvements may be used without others.
An air filtering unit comprising a pair of spaced substantially parallel circular plates each having a pair of circular flanges one at its periphery and the other adjacent its center, extending toward the other plate; a tubular support for the plates, of smaller diameter than the flanges thereof, extending from the center of ne plate through the center of the other and rigi ly fastened to the latter, the protruding end of he support being adapted to connect to an air ntake line, and said support having an aperture opening into the space between the plates for passage of air; a pair of cylindrical grids having the surfaces thereof covered with flock, mounted between the plates, respectively engaging the peripheral and center flanges thereof to be positioned thereby; a pair of rings having flanges mounted against the inner surfaces of the circular plates, said plate having means for positioning the rings centrally of the plates; a zigzag grid covered with flock, mounted between the plates and engaging the flanges to be positioned thereby, said grid extending in a star-shaped path between the cylindrical grids so that air entering the aperture of the support will first pass through the grids consecutively and be filtered thereby; and means demountably fastening said one plate to the support so that the grids may be demounted when the plate is removed.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Name Date Young Oct. 13, 1903 Dunlap Apr. 19, 1910 Blanchette Feb. 2, 1915 Foster Mar. 13, 1917 Porter Mar. 27, 1917 Goodloe Jan. 29, 1929 Slauson Sept. 24, 1929 Orem Aug. 11, 1936 Campbell Feb. 6, 1940 FOREIGN PATENTS Country Date 1 France Oct. 30, 1936; France Oct. 14, 1938 Great Britain Mar. 6, 1930 Great Britain May 11. 1933 Number