US2274684A - Filter medium and filter body made therefrom - Google Patents

Description

March 3,. 1942.

Filed NOV. 16, 1940 vf fi/ kw? @if .m @mf/MFA @y Y Mmmm www, 54M

A. M. GOODLOE YFILTER 'MEDIUM'AND FILTER BODY MADE THEREFROM INVENTOR.

ATTORNEY,

March 3, 1942. A. M. GooDLoE- n 2,274,684

FILTER MEDIUM AND FILTERBODYMADE'THEREFROM INVENTOR.

- ATTORNEY.

Patented Mar. 3, 1942 sans n m'rua Mmmm am mgm. nom? ma :lui: '.l' l

Alfred M.-Goodloe, Montclair, N. J., aeslgnor to Metal Textile Corporation, West O rauc, N. 3., a corporation of Delaware Application November 16, 1940, Serial No. 365,92#

4 Claims. This invention relates, generally, to anl im- (Cl. 18a-69) `upon themselves.

proved illter material for use in wet, viscous or vsemi-dry types of air and gas filters; and the invention has reference more particularly to an improved lter material in the form of a single ply warp knit metallic mesh fabric.

Wet, viscous or semi-dry air and gas filters have heretofore been used in which the porous lter medium employed has comprised a tubular knit metallic fabric. flattened to the form of a two-ply sheet; the sheet or sheets .thus formed being superposed or rolled upon themselves to produce the desired mass of illterybody. Such .two-ply metallic fabric when formed into the desired lter mass or body has certain disadvantages due to its two-ply form. For example, when the tubular knit fabric is flattened into sheet form, the knitted loop strands andloop openings of the opposed plies are disposed in asymmetrical relation with the strands brought into abutting or close contact one with another, with the result that distribution of the metallic material and of the loop openings of the contiguous plies lacks uniformity, and consequently eilect of the metallic materialas well as the porosity of the mass is likewise lacking in uniformity. Such lack of uniformity in these particulars makes for uneven resistance to flow of air or gas moving through the filter body. and also increases the likelihood of choking at points of excess resistance, especially where loop strands are closely aggregated in thecontiguous plies. Furthermore, such lack of uniformity renders difilcult the process of washing out the filter body when cleansing thereof is necessary.

Having in mind the disadvantages of a tubular knit two-ply metallic fabric in the make up of a wet, viscous or semi-dry illter body, an object of this invention is to provide a single ply metallicfabric for use in making up a filter bodyof such type which avoids said disadvantages. To this end I provide a single plywarp knit metallic fabric made of comparatively stiff wire, whereby the interengaged loops forming the l fabric tend to resist relative displacement and consequently tend to retain and maintain the initial shapes and uniform distribution of the loop denned openings throughout theol-ea of the fabric, as well as a considerable degree of self-supporting stability due to inherently greater resistance to both contraction and elongative stretch of the fabric; with the result that suoli` single plywarp knit fabric may be readily built up into a lter body of. desired mass by superposing sheets thereof or by rolling strips thereof in such manner as to obtain a uniform relative spacing of the layers, and consequent substantially uniform porosity of the body mass, thereby to assure, without loss of dust capturing capacity. a filter mass of substantially uniform resistance to air or gas movement therethrough, less tendency.. to clog or choke, and one more easily and efficiently penetrative by a .cleansing agent.

Another object of this invention is to provide a single ply knit metallic fabric having novel selvage edge formations especially advantageous in the make up of lter bodies of the oil bath type. wherein said selvage edges function to prevent oil pullover, facilitate oil run back, and prevent clogging. by coarse foreign substances.v of the air or gas entrance area of `such lter Other vobiects of this invention, not at this time more particularly enumerated, will be understood from the following detailed description of the same. l

Illustrative embodiments of this invention are single ply warp knit metallic fabric for making up nlter bodies according to'this invention; and Fig. 2 is a vsectional view thereof taken on line 2-2 in Fig. 1: Fig. 3 is a schematic face view of superposed corrugate'sheets of such single ply warp knit metallic fabric adapted for building up the mass of a desired filter body, in such manner that the superposed sheets arev uniformly spaced by said corrugations; and Fig. 4 .is a sectional view, taken online 4-4 in Fig. 3.

Fig. 5 is a cross-sectional view. with parts in elevation, of an oil bath vtype air filter equipped g with 'a filter body made of the single ply warp knit metallic fabric having novel selvaged edges according to this invention, said illter body being shown in part side elevation and in part transverse vertical section.

Fig. 6 is a perspective view of a ilatvtype air nlter or screen device equipped with a filter bodv made of the single ply warp knit metallic fabric according to this invention: and Fig. '7v is a vertical cross sectional'view thereof.

An illustrative form of `single ply knit metallic fabric comprises a plurality of warp strands of wire II which are interlinked together by knitted loops I I, thus providing a single open mesh sheet or'stripy like body. The number and spacing of the warp' strands il are so predetermined as to provide a widthv of fabric according to that required in the make up of a tllterbody or mass vof desired dimensions. The warp strands I0 comprise wires of comparatively stiff character,

and this fact, together with the form and interlocking relation of the interlinked knit loops Il,

produces a mesh fabric which is quite resistantv to contraction and stretch so that the apertures,

due to its' warp knit character, is provided along its opposite margins with selvage edges formed by outstanding free loops I2 spaced therealong. These loops may be wrought into desired shapes other than the. S-shape shown, as, for example, into inverted Ushape. In certain types of lter bodies, the selvage .edges thus provided have devided advantages, as will be hereinafter subsequently explained.

Filter bodies, made'up' of superposed sheets or layers of single ply mesh fabric of the general character above set forth, may be utilized with the plane of the mesh opposed to the direction of air or gas fiow therethrough, or with they plane of the mesh parallel to the direction of air or gas flow therethrough, accordingly as is most desirable under various conditions of use.

In filter bodies comprising superposed layers or sheets of the described single ply knitted metallicmesh, the stability of the mesh readily lends itself to uniform spacing of its contiguous layers, and since the apertures provided by and between the knitted loops of the mesh tend to maintain their initial shapes and uniform distribution, the porosity of the filter body and density of its mass is substantially uniform in ing pockets tending to greatly retard and sometimes even prevent-oilA run back. lOn the" other hand, duel to the more uniform resistance to air fiow attained in the body composed of single .ply mesh layers, i. e. air flow without varying restriction and impedance at different points within the body mass,`there is less chance of unevenv ous plies, as occurs in a two-ply mesh of the flattrance air area of the filter body. This is particularly true where the air flow is parallel to the plane of the m esh layers, since the selvage loops I2 provide a more open entrance area, while at the same time serving to fend off relatively large foreign particles, such as flakesof leaves, paper or the like, -in such manner as to 'prevent blanketing or choking thereby of the air entrance area of the filter body. Again due to the substantially uniform porosity of the filter body 'mass and elimination .therefrom of small obstructing pockets, dust masses accumulated thereall parts thereof, thus not only uniformly dis- Y resistance attained in the filter body according g to this invention permits the movement of a given volume of air through the body with less expenditure of power, or the movement of a greater volume of air with a given expenditure of power. 'f

In use, the einer body is wet with suitablevfiuid so that the metallic strands of the mesh are enabled to capture dust particles carried by the air when impinged thereupon. Wetting fiuids such as oil or other more or less viscous fluids are ordinarily employed, in which the filter body is immersed to coat the strands therewith, or which is caused .to fiowinto the filter `body .with the air` or other gas. In a filter body according tovthis invention draining of oil-.from an immersed body is more quickly and efficiently attained; while in the oil bath type of filter run back of the oil is likewise more rapid and eflicient, since the oil fiow is subject to less obstruc tion by the single ply mesh than is the case with a two-ply mesh of the attened tubular knit type, wherein intersections of loop strands of the contiguous plies form obstructing dams and holdin `in use may be more quickly and efiiciently washed out and away therefrom by a penetrating cleansing agent 4or fluid.

In Fig.' 5 is shown a filter body according to this invention f or use in an oil bath type of air filter, such e. g. as employed in connection withv the air intake of an internal combustion engine carburetor. An illustrative conventional form of oil bath type air filter as shown, comprises a cas# ing 20 formed to provide in its lower portion an oil reservoir or basin 2|, and an annular filter v body housing 22 above said reservoir or basin which opens into a domed top 23 leading to a central cleanair discharge conduit 24 around Y which'said housing 22 is disposed. The casing l 20 provides external side walls extending upwardly from said reservoir or basin 2l, said side walls being -spaced outwardly from the filter body housing 22, thereby to provide an annular air intake passage 25 leading into said reservoir or basin, and thence communicating with the lower or air receiving end o'f said filter body housing. I

A filter body 30 according to this invention is positioned Within the housing 22, so as to fill the interior thereof. Thisfilter body 30 is formed by winding upon itself a strip of the single ply metallic mesh; said strip being of a width corresponding to the required height.of the filter body mass. Thestrip of single ply metallic mesh is thus wound upon itself to form an' annular body sized for insertion Within the housing 22 so as to fill the interior thereof. When the strip of single ply metallic mesh is wound into such body form, thefreely projecting selvage edge loops I2 will project fromboth the air ingress and air egress ends of the formed body to provide air intake and air outlet areas of considerably less density than that of the. main body of the resultant lter mass, thereby to provide a novel construction with the attendant advantages hereinafter subsequently mentioned.

In the `operation of the -.ol bath type filter equipped with the novel filter body according to this invention as described, under the suction to which its air discharge passage is subjected in use, airis in-drawn through the intake passage 25and caused to take up from the reservoir or basin 2| and carry on therewith some of the oil with which the latter is supplied; such oil charged air thereupon enters through the bottom intake area of the filter body 36, for upward movement through the mass of the latter, so that the carried oil is deposited upon and so as to wet the strand surfaces of the mesh of which the lter body is formed. The wetted strand surfacesv are thus rendered capable of capturing and holding dust particles moving in and with the air stream into impingement upon such wet surfaces, whereby the dust is separated from the air. l,The air thus purified discharges from the top outlet area of the filter body for delivery through the discharge conduit 2d to the engine carburetor served by the filter.

In air'lters -used in connection with internal combustion engine carburetors, especially in the automotive field, there is frequently sucked into the lter coarse foreign material such as small pieces of paper, feathersfleaves and leaf flakes, and other aky bits and the like. Among the advantages of the less dense bottom intake area of the filter body, which is provided by the freely projecting loops I2 of the lower selvage edges of the described single ply mesh strips are the following. Such selvage edge loops I2 provide spaced apart downwardly projecting fingers which serve to arrest and fend of any bits or akes of foreign material so that the ingoing air may pass around such material into and through the main filter mass without obstructing ingoing movement of the air or causing undue rise ofresistance to air flow through the filter mass. Should an accumulation of such bits or flakes of foreign material occur, or the same entangle with the spaced selvage loops I2, they cannot work deeply into the main filter mass, and will be so loosely held by the selvage loops I2 or fingers formed thereby as to be subject to quick and `easy removal by the down wash of oil when the latter i runs back to the reservoir after the engine is shut down and the inrush of air thereby stopped. Another advantage of the spaced downwardly projecting free loops` I2 of the lower selvage edges oi the filter body mesh, is that the same tend to separate the emerging oil streams during oil run back so as to break down any tendency of the run back oil to accumulate in the lower portions` of the filter, and by adhesion or capillary eie'ct of the mesh be so held as to obstruct its quick discharge.

` of oil pull over.

thereby notonly defeatingl eflicient air cleaning"` functioning of the filter, but also wasting oil. Due to the presence ofthe spaced upwardly projecting fingers formed by the selvage edgeI loops I2 upstanding 'from the top outlet areas of the filter body, and by reason of the lessdense chara'cter of said top outlet areas formed thereby, the oil under the pressure of air flow tends to creep up on the loop formed fingers, thus preventing the oil from 'accumulating in more or less consolidated masses. The oil thus deposited on the loop formed fingers tends to cling thereto' with less back pressure effect upon the air flow, and consequently is less likely`to be blown off and thereby pulled over into the outgoing air stream.

As a consequence of s'uch eiect of the loop formed ngers, thev air stream may be caused to move at somewhat higher velocity with less risk In Figs. 6 and 7 is showna nlter structure of th'e air screen type such, for example, as used in air-conditioning installations and the like. For

such types o f filters, the novel filter body comprises a lter mass 40 formed .by superposed layers of the single ply knit metallic mesh, and such `iilter mass is supported in a suitable frame 6I in such manner that the plane of the mesh layers is perpendicular to the direction of air flow. The

filter mass 40 also includes the less dense areas In oil bath type air filters used in connection with internal combustion engine carburetors, the oil taken into the filter, when the air reaches a ,certain velocity', tends to accumulate in pools or masses in the upper sections cf the filter body. thus offering such resistance to air outflow es tends to cause the air pressure to blow or pull off drops of oilwhich are carried away with the outtween the reservoir and filter mass is interrupted,-

at the top and bottom 'ends which are provided by the loops I2 of th'e selvage edges of the-mesh.

Such less dense areas are also somewhat more rey sllient, and consequently permit of easy fitting of the mass into the frame without necessity for too precise dimensioning of the filter mass. When used in filter frames or screens of this type the novel filter mass provides the general advantages and' eflclency characteristics already above noted.

. As shownin Figs. 3 and e, in making up lter bodies from single ply knit mesh by superposing sheets or layers thereof, the mesh sheets or strips may be optionally 4nrst corrugated so that corrugations I3 are formed to extend obliquely across the width of the sheets or strips from one selvaged edge to the other. When assembling the sheets or strips in superposed filter body forming relation, by either piling or winding the corru'ga- .v

tions of alternate sheets-are disposed to cross each other, whereby the sheets or layers are spaced by said intersecting corrugations. This modified arrangement -is found to be especially advantageous for filter bodies desired to be somewhat less dense or of more open character.

Having now described my invention, I claim:

1. 'A filter body comprising a plurality of layers of warp-knit single ply metallic mesh made of comparatively stiff wire, each layer having along opposite margins thereof selvage forming sub-l stantially rigid loops, the aggregation of said selvage loops spaced apart in separated relation one to another and disposed to freely project from said margins in the -plane of the layer providing filter body -portions of .less density than that of the main portions of the filter body.

2. A 'filter body comprising warp knit single ply metallic knit mesh fabric, said fabric having along longitudinal margins thereof freely pro-'- jecting spaced selvage forming loops, said fabric being rolled longitudinally upon itself to provide body end portions of less density than that of the main portions-of the filter body.

disposed at ingress and egress ends thereof, the

aggregation of said selvage loops providing lter body end portions of less density than that of the main portions of the filter body.

4. nner body comprising warp knit single p1y metallic mesh strips, said strips having along longitudinal margins thereof freely projecting spaced selvage forming loops, said strips having corrugations extending diagonally between their longitudinal selvage margins, at least two of said strips being superposed so that the corrugations of one cross those of the other, and said superposed strips being rolled longitudinally upon themselves to provide a lter b ody wherein said selvage loops are disposedat ingress and egress ends thereof, the aggregation vof said selvage loops providing iilter body end portions of less density than that of the main portions of the filter body.

ALFRED M. GOODLOE.

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