US 2122582 A
Description (OCR text may contain errors)
mm m T F I 2 @WAW R F. NORRIS July 5, 1938.
FILTER Filed Nov. 9, 1934 Patented July s, 1938 Ralph Forbush Norris, Madison, Wis, assignor to O. F. Burgess Laboratories, Inc., Chicago, 111., a corporation of Delaware Application November 9, 1934, Serial No. 752,246
8 Claims. (Cl. 183-45) This invention relates to improvements in filters and in particular filters used for cleaning the intake air of internal combustion engines.
Among the objects of this invention are the providing of a. highly efficient cleaner which has a high capacity, has a low air restriction, oc-
' cupies a relatively small space and is relatively cheap to construct.
The following specification should be read in connection with the accompanying drawing in which: I
Fig. 1 is a detailed view showing the construction of the gimped material of which the filter is made;-
Fig. 2 is a sectional view of an annular cylinder filter unit incorporating the gimped material of Fi Fig. 3 is a side elevation of a cross-wound cylindrical filter in which the carrier strands only are shown for-clarity; and
Fig. 4 is a view similar to Fig. 1 showing a construction in which a plurality of gimped members are arranged upon a single carrier strand.
Air filters satisfactory for internal combustion l engines and especially automobile engines should have the characteristics listed above. The filter of my invention. has these characteristics.
The gimped material ID of Fig. 1 is the basis of my improved filter body. It is made of a central flexible carrier strand l2 about which a second strand i4 is wound or gimped in the form of a helix. The strand I4 is made of a springlike material so that the helix is substantially a helical spring along the length of carrier strand II. The use of this springlike and resilient helix for the gimped material is a novel feature of my invention. Strand if is preferably made of metallic ribbon. Mechanically worked copper ribbon is usually used although aluminum, iron and any other metal or alloy may be used which has the desired physical properties or which may be either heat-treated or physically worked to give it the desired resiliency or springiness. Copper is the metal which is favored at present for automobile engine filters.
Excellent results are obtained with a filter body made as hereinafter described from a gimpedmaterial made or spring-like copper ribbon strands 0.025 inch wide b 0.002! inch thick, the helical spring being 0.1 5 inch in diameter with 18 coils per inch of length. These dimensions are merely illustrative, and my invention is not limited to gimped material made from copper ribbon of these dimensions.
Although the carrier strand i2 is indicated as being made of metal ribbon, nevertheless it may be made of any suitable flexible material which may be ordinary wire, yarn, textile cord, or any textile fabric which is not too large in proportion to the helix.
The shape of the filter body is determined annular cylinder as shown in Fig. 2 is used to a large extent for automobile intakes.
It is apparent that the type of winding also affects the characteristics of the finished cleaner. For example, winding under considerable tension results in a compact cleaner having small openings and a high restriction. The gimped material may be spool-wound, which is the type of winding used on ordinary spools ,of thread. It may also be cross-wound as shown in Fig. 3, this type of winding being preferred.
The preferred cross-wound filter body of Fig. 3 shows a structure in which the strands of gimped material in any one layer are spaced apart. The adjacent coils in any layer preferably are spaced apart at least about the diameter of the coils except at the edges where overlapping occurs. This spacing of the strands when combined with a light tension produces a filter body that is highly eiiicient with the above described gimped material. The cross winding should be effected in such a manner that a honeycomb structure is not produced, that is, the strands in alternate layers should be staggered as indicated by strand ii in Fig. 3 and should not be in alignment. As shown the layers are wound about a single'axis of the frame. The direction of the air flowing through the filter thereby is changed frequently. A more homogeneous filter body also is produced thereby. The annular cylindrical filter body of Fig. 2 may be produced by cross winding in the absence of retaining side walls. Such side walls are necessary if spool winding is used in order to keep the strands from rolling outwardly. Furthermore, cross winding prevents bunching of the gimped material which is characteristic of spool winding and thereby produces a filter of uniform porosity. It is essential to type are dipped in oil and drained before being put into service, the retained oil catching the dust passing through the coils. Each loop of the coils of wire is an eflicient retainer of 011 since the oil gathers as a droplet at the bottom thereof. These coils therefore retain a large amount of oil which in turn catches a large amount of dust. Because of the large number of loops and the large volume of voids the filter is capable of retaining a large quantity of dust before becoming clogged and it therefore has a high capacity.
Since the flexible carrier strand is relatively straight its oil retaining capacity is small if it is made of a single strand of metal. It therefore does not contribute greatly to the dust retaining capacity of the filter. Twine or cord or similar absorptive material functions mechanically in a manner similar to metallic wire or ribbon when used as the carrier strand. However, it retains a relatively large amount of oil] because of its wick-like properties and thereby adds to the cleaning efiiciency and dust capacity of the filter. I
When the filter is made in the form of an annular cylinder the gimped material I8 is cross wound exteriorly on a cylindrical screen or cloth 20. A second cylindrical screen or cloth 22 is mounted exteriorly of the cross wound gimped material where it may be soldered in place. The exposed strands of gimped material at the ends of the cylinder catch readily on any projecting points and therefore it is desirable to tie them in place to facilitate handling during assembly operations and during service. This is done by laying, before winding, four or more strands of gimped material 24 on the face of the inner cylinder 20, parallel to the axis thereof. These strands, being longer than the cylinder, project beyond the end and are held in this position on the face of the inner cylinder when the filter is formed upon them. After the winding is completed the projecting ends of these tie strands are turned over the ends of the annular cylinder of gimped material l8 as shown at 26 and held between the outer cylinder 22 and gimped material i8 when the outer cylinder is slipped into place.
In Fig. 4 of the drawing the gimped material 30 comprises a central flexib-ie carrier strand 32, having a plurality of strands 34 wound or gimped thereon in the form of a helix. The form shown in Fig. 4 consists of a pair of gimped strands arranged upon a single carrier strand, but will be apparent that any number of strands may be gimped on the carrier strand. The gimped material of Fig. 4 possesses the characteristics heretofore described in connection with Figs. 1 to 3 and it may be used in the construction of a filter body by winding it into the desired form as heretofore described in connection with Figs. 2 and 3, of the drawing.
The above specific example of my invention illustrates the principles involved therein. It will be apparent to those skilled in the art that constructions may be used which vary in detail over a considerable range and that equivalent constructions may be used without departing from the scope of the fc-ilowing claims. Two or more strands of the gimped material l0 may be wound'simultaneously to form thefilter instead of the single strand as described.
1. A filter body comprising an interstitial structure of a plurality of overlying layers of strands of gimped material comprising a flexible carrier strand having one or more metallic spring-like ribbons gimped thereon in the form of a continuous helical spring wound about said carrier strand throughout the length thereof. said strands of gimped material being wound upon a foraminous cylinder, the strands or" gimped material being cross wound, and the strands in any one layer being spaced apart.
2. A filter body in the form of an annular ring comprising overlying layers of cross-wound strands of gimped material comprising a flexible carrier strand and one or more metallic springlike strands gimped thereon in the form of a continuous helical spring wound about said carrier strand throughout the length thereof, said spring-like strands having sufficient stiffness to retain their shape when in operation in a filter of the type herein described.
3. The filter body of claim 2 in which the carrier strand is under light tension and in which the spring-like strands are in the form of ribbon.
4. The filter body of claim 2 in which the strands of gimped material in any layer are spaced apart on the average a distance equal to at least the diameter of said helicai spring.
5. The filter body of claim 2 in which the strands of gimped material in any layer are spaced apart, and the strands in alternate layers are staggered to change the direction of the air flowing through the opening between said spaced apart strands.
6. A filter body comprising an interstitial structure of a plurality of overlying layers of one or more strands of gimped material comprising a flexible carrier strand having one or more metallic spring-like strands gimped thereon in the form of a continuous helical spring Wound about said carrier strand along the length thereof, the strands of gimped material in one layer extending crosswise cf the strands in the adjacent layer and the strands in any one layer being spaced apart.
'7. A filter body comprising an interstitial structure of a plurality of overlyin= layers of one or more strands of gimpefmaterial comprising a flexible carrier strand having one or more metallic spring=1ikc strands gimped thereon in the form of a continuous helical spring wound about said carrier strand along the length thereof, the strands of gimped material in one layer extending crosswise of the strands in theadjacent layer.
8. The filter body of claim 2 in the shape of an annular ring mounted between two telescoped foraminous cylinders, the gimped material being wound upon the exterior surface of the inner cylinder.
RALPH FORBUSH NORRIS.