Air impeller housing
United States Patent 2442420
1U Ola mS 1 This: invention relates to improvements in air impeller orfanl housings and in methods of constiucdtng'them. The inventitnrelatesmore particularly to the structure and fabrication of impelleri'hou~ings of the general type showriin-the Vani Drn Patent No. 2,349,315, May 23, 1944....
Inventors:
Lindvall, Frederick C.
Beemer, Paul K.
Montgomery, Paul H.
Application Number:
Publication Date:
06/01/1948
Filing Date:
09/04/1945
Export Citation:
Primary Class:
Other Classes:
415/182.1,
415/214.1,
415/215.1,
International Classes:
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US Patent References:
22937202264897223106321574411484579
Foreign References:
Description:
1U Ola mS 1 This: invention relates to improvements in air impeller orfanl housings and in methods of constiucdtng'them. The inventitnrelatesmore particularly to the structure and fabrication of impelleri'hou~ings of the general type showriin-the Vani Drn Patent No. 2,349,315, May 23, 1944.
Impeller-housingsof that type embody an elongate box-like structure of-sheet metal, with top arid bottomdiwalls and-discontinuous or sectional side walls. The side wall sections along opposite sides re reelatively staggered along the length of the b6x, and transverse, partitions join the-side wall-sections in such manner as to form chambers which, pr6ceeding along the length of the box, openi0out alternately to opposite sides of the box. The several partitions have central circular openings-which are alined on a central longitudinal axis arnd a single drive shaft extending through the box :onthat axis carries air propeller fans in alternate chambers, that is, in the chambers which open out to one side of the box.
Difficulties have been found in fabricating such a housing inexpensively and in providing a finished structure which at the same time is- sufficie6tlyi strong and rigid to take -the static loads 2i and shock-loads to which the structure is subjected in' without distortions that will throw the shaft bearings out of alinement, those bearings being mounted on thestructure. Previously it has been the practice to flange the various comipoliebts and to weld them together either by nmarual arc or spot welding. That fabrication has-pr6vided for amnple rigidity but has been relatiVielyslow and expensive, due largely to the factthat the welding points have necessarily been 3 located in different situations where no single and siimple repetitive welding operation could be expeditiouiily applied.
It is one of the features of the present improvemerithtthat the entire operation of securing the coiiponient parts together involves nothing but the repetition of a simple operation applied only to the top and bottom faces of the structure. The securing points are easy to reach and the securing 4 operationri is very simple.
Another feature of the present improvements lies in the fact that the general design, and that of the securings, are such that fully welded connections are not necessary, connections of a forged riveted or headed type giving ample rigid- 5 ityto the finished structure. Temperatures need not be as high as requiredfor true welded connections and danger of buning the thin sheet metal is avoided. Ad a further-feature isin the provision of mounting plates, for the shaft bearings, which are secured in the structure in the same manner as the .transverse partitions and side wallsi -serve to further stiffen the structure, and requireonly repetitions of the same simple securing- operation.: The-features and characteristics of the invention will: be best understood from the following detailed description of typical structures and procedures embodying the invention, reference for the purpose of such description being .had to the accompanying drawings, in which Fig. 1 is a-plan, with part of the top plate broken. away, showing a housing- structure typi Fig. 2 is an enlarged fragmentary plan of the structure shown in Fig. 1, w Fig. 3 is a plan of the- corresponding portion of the- Fig. 4-is a vertical cross section taken as indicated by line 4-4 on Fig. 2, showing the top plate in placeand the-parts assembled ready for the Fig. 5 is asimilarsection online 5-5 of-Fig. 2; F 6 is a fragmentary plan-section of parts corresponding to those shown in Fig. 2 but showing the complete ass Fig.-7 is a cross section on line 7-i of Fig. 6; F 8 is a cross section on line 8-8 of Fig. 6; Fig. 9 is an enlarged detail section showing one Sunit of the securing means assembled ready for the fina Fig: 9a is a similar view showing another unit o Fig. 10 is-asection on line -0-10 of Fig. 9; Fig. 11 is a plan of the parts shown in Figs. 9 and 10; Fig. 12 is a bottom plan of the apertured part of a plate which forms one element of the securing .unit of Figs. 9, 10 and 11; 0 Figs. 13 and 14-are sections similar to those of Figs. 9 and 10 but showing the parts as they appear after the fina Fig. 13a is a-view similar to that of Fig. 13, but showing the securing unit of Fig. 9a; 5 Fig. 15 is ant enlarged vertical longitudinal-section online 6-15: of Fig. 7; Fig. 16 is an end elevation of suitable apparatus on which the repeated securing operations a and>0 Fig. 17 is an enlarged-detail section on line 1-17i ofFig. 16.
As showniillustratively inthe drawings, the casing is comtposed mainly of a bottom plate 20; top plate' 21, and"vertidal plate units 22 which pro5 vide both the sectional side wall units 23 and the transverse partition units 24. All these part and the bearing mounting plates 38, are con posed of relatively thin sheet metal. To give a idea of relative dimensions, a housing about 9 inches long and with a transverse body dimen sion of about 8 inches, is constructed entirely c sheet metal 0.105 inch thick. As is seen in F 1 and 2, the side wall sections and the transvers partitions make a formation, in plan, which ma: be described as being rectangularly sinuous. Th formation is such that the several side wall sec tions 23 and partitions 24 may be formed of single long sheet of metal bent to the desirec conformation and provided with the aperture, and tabs which will be described. And accord ingly the several vertical plate units 22 may b( considered as collectively forming one long sin. uous unit which includes all of the side wall sections and the transverse partitions. However, we prefer to make up that long unit of a plurality of duplicated units, such as the units 22, because of the manufacturing complications involved in makning the single long unit with the accuracy which is required of that unit to fit the other parts. The single long unit cannot be produced in one operation, whereas the small duplicated units can be simply produced by die pressing.
This subdivision into short duplicate units also facilitates the provision of drainage openings, as will appear.
Accordingly, the side wall sections and partitions are provided by a series of units 22, each of which is rectangularly U-shaped in plan.
These n e units are assembled in the configurations shown in Figs. 1 and 2, and in the final assembly are preferably separated by the slight vertical gaps shown at 25 in Fig. 2. While the several units might tightly abut at 25 at their meeting edges, slight gaps at those meeting edges provide convenient drainage escapes for water which might otherwise collect at one side of the casing. As shown in the issued patents previously referred to, these impeller casings extend transversely across the car floor, and unless some facility is provided for drainage of water past them, water from a car loading may bank up against one side of the casing. The provision of the drainage openings, easily provided by the gaps between unit 22, allows such water to pass the casing to find an outlet.
Although the several U-shaped wall units 22 may be full duplicates of each other, we prefer to make the units 22 which lie at one side of the casing a little wider than units 22a which lie at the opposite side of the casing. All units 22 are full duplicates and all units 22a are full duplicates. The resulting formation is such that the chambers 26 which are open at one side of the casing are somewhat wider than chambers 27 which open at the opposite side of the casing.
The wider chambers 26 are the ones which take the impeller fans, as will be described.
As shown in the drawings, the complete sinuous wall unit, made up essentially of units 22 and 22a, also includes a pair of end units 22b ( which, instead of being U-shaped, are L-shaped, and are composed of a partition section 24 and a short side wall section 23a. The standard and duplicated unit 22 and 22a, are made up of a side wall section 23 and of two partition half sec- 7 tions 24. Each partition, when the parts are assembled, is thus made up of two half sections.
Each partition has in it a circular opening made up of two semi-circular openings 30 which are formed in the two half sections 24. This cir- 7, ,442,420 4 s, cular opening is flanged at 31 to stiffen the pari- tition members, and to provide smooth and effin cient air flow through the opening into the ceni6 ter of the fan.
1- To make the structure of Figs. 1, 2 etc. more )f intelligible, we refer now to Figs. 6, 7 and 8, which s. show the structure and arrangement of the come plete finished impeller unit. As shown in those Y figures, the wider chambers 26 accommodate ime 10 peller fans of the radial blade type, such as - shown at 35. These fan units are set on their a single longitudinal shaft 38 which extends cen1 trally longitudinally of the housing structure s and is mounted in bearings 37 which are car- 15 ried on vertical bearing plates 38 located in some e of the narrower chambers 27 and, in one instance, located in the end space within one of the end S units 23b (see the right hand end of Figs. 1 and S 6). These bearing plates 38 are mounted on and 20 assembled with top and bottom plates 21 and 20 in the same manner that units 22 are assembled with those plates, so that the bearing plates become a rigid part of the finished structure, help to stiffen it, and maintain a rigid relation to the 25 partition walls of the structue and to each other.
The bearing plates are shown in Figs. 4 and 7, and Figs. 6, 7, and 15 show the mountings of the bearings 37 on those plates. The bearings proper are shown as ball bearings 40 mounted on 30 shaft 36. The outer members of these bearings 40 are mounted in internally grooved rubber rings 41 which have external grooves fitting interiorly into a flange 42 of a bearing base plate 43. Each bearing mounting plate 38 is provided 35 with a central opening 44 of sufficient size to accommodate ring 41 with clearance, and each plate 38 is also provided with a pair of slotted bolt openings 45 which are elongate in one direction, say vertically. Each bearing base plate 43 40 is provided with registering bolt holes 46 which are elongated horizontally. The arrangement provides for easy adjustment of all the bearings 37 in axial alinement on the finished and rigid housing structure, the bolts 48 being set up when 45 that alinement has been adjusted. Ears 49 are turned down against the bolt heads before setting up the nuts, and the latter are locked with an ordinary lock washer. When finally set in position, the several bearings are rigidly secured 60 to their several mounting plates 33. And, as will be seen, our invention provides a structure in which the several bearing plates 38 are rigidly maintained in alinement with each other and in alinement with the other parts of the structure. 55 Freedom of the bearings for angular alinement is allowed by the rubber rings 41.
The narrower chambers 27, in some of which the plates 38 are mounted, provide the chambers or passages by which air enters the casing from 60 one side, the air then passing through the partition openings 30 endwise into the impeller fans, and then being thrown out at the opposite side of the casing by the rotary action of the impeller fans.
I5 Going back now to Figs. 1, 2. and 3 we will explain how the various wall units of the casing, and the bearing plates 38, are assembled and secured in a rigid assembly. Each unit 22 is provided, along its top and bottom edges, with a 0 series of spaced, projecting, rectangular tabs 50, arranged in plan as is best shown in Fig. 2. At the edges which meet or form the gaps at 25, each of the units is. provided, on the top and bottom edges of its partition sections 24, with projecting tabs 51 which are only half the width .5 ~o-tas-50,-or preferablys omewhat:less than half ,wydth. ,The special end units 22b are provided ,ithsimalar tabsj50a and 5 1. The tabs .50 and 51 on-all units 2 are duplicates as .to size and ar' a4Agement, Iand. the same is true of all the tabs on- unit -2'2a. In- the :assembled. formation shown -in Figs .and- 2, the several-projecting-tabs of all .tihe'assebled uanits forpm a certain definite pattern at's-both the top and bottom edges of the -.assembled-:units.
"-Bearing mounting plates .38 :are provided at their, topand bottom edges with the same spaced t, bsa-5, arnd these tabs, in the final assembly, bear a, definite pattern relationship in plan to.thepat-temrn f the other tabs. r .. oth the bottom and, top plates 2 and .2 are .provided- with perforations 55 arranged on the SasseiBsly .pattern of tabs 50 and 5i and thus .ldapted. to. take and pass the several tabs 5S and .51-,when the parts are assembled. Perforations .55,areali of duplicate:size, a little larger than ithe cross-sectional size of tabs 50. This includes the -perforations 55a each of which take a pair .of- the.ehalf-sized tabs- S. rFig. 3 may be under:.steod'to show the pattern arrangement of the. .perforations in both bottom and top plates 20 .andj 21.
F . 9 to 12 show in enlarged detail the pre-ferred formation of the -tabs and perforations and their ,relationship to. each other when initially ,assembled, and-ready for the securing operations.
"These. figures-show a plate, for instance the half portion plate 24 with a tab 50 projecting through San opening-55 in top plate 21. The illustrations ,are however typical of all tabs 50 and their re,,ceiving perforations. The special openings 55a .which-taqlke the half tabs 5i are shown in Fig. 9a .in-'their initially assembled positions, and in Fig. 13a in-their -finally secured conditions.
' As shown in Figs. 9 to 12, the top plate 2 (and -likewise bottom plate 20) is exteriorly recessed .around- each opening 55, preferably with a recess :60 which is -circular in plan. The diameter of this -external recess is preferably slightly larger than the length dimension of opening 55. The recess is formed by. pressing the sheet metal inwardly,. in the same die pressing operation by which .openings 55 are formed. The recessing Soperation of course results in a corresponding .tonvex-protuberance C1 on the inner face of the sheet metal. plate 20 or 21, which protuberance .has, adiameter somewhat larger than the length sdimension of perforation slot 55. And, in order to allow-the: edges 62 of the vertical plates 23, 24, -etc. to lie directly against the inner faces of the top and, bottom plates, the areas at 63 on the inner faces, of the top and bottom plates which .would otherwise project slightly inward of those -inner-faces, are left flat in the same die-pressing operation to be flush with those inner faces. The resulting inner face-formation is shown in Fig. 12 ,where the perforation slot 55 is shown to have a less than semi-circular bulge at each of its longi..tudinal edges, but no bulge exists at its end edges.
As a -result of the described formation, the upper and lower edges of all the vertical plates or. sheets are-allowed to abut the inner faces of the top and bottom sheets, and the opposed straight edges 61a of the bulges 61 overhang the ,edges of-the vertical sheets on each side. Tabs .50eproject through the openings 55 and upwardly through and beyond the recesses 60. Proportionte, dimensions which have been found suitable .a;d.practicable for the assembly are shown in .he enlarged .detail figures, although of course the invention is .not tto be. limited to: the particular proportions illustrabted.
Fig. 9,ashows how :thesemi-tabs 5 - into-.and through the perforations,5.a, which.are identical with, and recessed:in the same m.anner, as .perforations 55. -When:the parts are initially assembled- they are as shown in Fig. 9Sc,,preferably with the gap .25 existing between the two partition sections-24- and between the two semir-tabss,s51. 0 T all the parts ,is .such Ithat, although perforations -.5 are all somewhat, Earger than the tabs 5thus allow some looseness when the parts are initially ,assembled,-thea gap at 25 is wide-enough that it will stillexist ,as-agap -even if two parts 24 happen ito be movedt, tward eachtlolseness yll..allaw.
The several components pf -the :whole p:asing assembly are -easily ,initially ,assembled.Ly -first laying down the. top r bottom plate on a skeletpn or lattice, support, and -then placing the several units.?22,-22a, 22-band 38 in their indieated,.assembly positions, with all of their: pweri tabs'rprFjeotin the corresponding perforations. Then -the .other, _plate is placed on: top the assembled vertical units and . by-slight adjustment of-.the parts all.of-the jupper tabs- are passed through the perforations in the plate which is placed on. top. Su.h,a -condition of assembly is indicated in Figs. 1, and.2 . ad-is shown in the sectional views ,-f-Figs. 4:,,and- 5.
0 The whole .assembly is then ready for the -final securing -operations which secure.all :of. the-various parts into one -rigid-.structure.
In their initially assembled condition, ,each! tab 5'3 or- 5 which-project2 . has a counter-part tabdirectly vertically oppossite it projecting- throughi-bottom plate:;20.. F 4:-.and for instance show how theetabs 5fl ndI : 1: on .vertical -units 24 :and -38 S.are arranged ,opposite 40each -other-at the- top .and bottom-those u4nits. And, as -stated, the patterns -of perforations in the top and bottom plate- are.othe same.
Consequentlyeach tab which projects ab:ovethe upper surface-of the initially assembled, structure 45 -has a corresponding tab directly opposite it projecting from the lower surface pf. the initially assembled- and that. arrangement.greatly facilitates the final securing operations. And all of these opposed pairs of tabs are substantial 50 duplicates of each other, the on!y difference being that the special tabs: 51 are, in: effect two parts which-together make:up a.co.mposite tab which is substantially like a tabu50. - That substantial duplication which exists throughout all of.the tab 55 sets,-and the fact that all of. the pairs of tabs have a common-positional relation .to the whole assembly, make it possible to perform the final securement by simple repetition of-a simpilesecuring operation.
60 Generally. described, the final securing operation consists in simultaneously .and oppositely - pressing and heating each pair of projecting tabs.
A suitable apparatus for performing the operation is shown in Figs. 16.and:17. A doubleheaded 65 apparatus of the electric welding type is provided, that apparatus, being here illustrated as having a U-frame 10 and .two -oppositely.- disposed operating heads 7 mounted in the frame-one above the other. A.carriage-2, is provided to:carry the ini70 tially assembled unit which is designated by the letter U in Fig. 16 and shown to be:supported in position-between the two heads 71. Carriage 72 is mounted on rollers- 3 on. a. suitable base 14 in such a manner:that ithe carriage can::be moved 75 -transversely of: its. lengths.and :of- thedlength.oof unit U; and the unit U is movable longitudinally of its length (normal to the plane of the drawing in Fig. 16) by sliding along the length of the carriage or by moving on transverse rollers 73a with which the carriage may be supplied. The arrangement has the result of allowing unit U to be easily moved either longitudinally or transversely with relation to t ohe opposed heads 71, and of being constantly maintaintaed in such orientation that when any upper projecting tab is brought under upper unit 71, the lower corresponding and opposite tab will be brought directly over the lower unit 71. With a pair of tabs in such positions, the two units 71 are operated simultaneously to perform the final securing operation on that pair of tabs.
Details of a suitable operating head for performing the securing operation are shown in Fig.
17. As there shown, the head includes a relatively stationary member 75 which has in it a cylinder 76 taking a plunger 7 er Plunger 77 is moved longitudinally (downwardly in Fig. 17) by admission of fluid pressure at 78. A pair of springs 79, seated upon lugs 80 which project from member 75, and acting on vertical studs 81 which move with plunger 77, are adapted to return the plunger to the normal position shown in Fig. 17 when the fluid pressure is relieved. Studs 81 are connected with ears 82 which are formed as extensions of plunger 77. The studs are connected to ears 82 3 in such a manner that the studs cannot move upwardly with relation to plunger 77 as for instance by having collars 83 under ears 82.
Studs 81 project downwardly below collars 83 and at their lower ends they carry a presser foot 3 member 84 slidable upon them. The presser foot member is supported by nuts 85 at the lower ends of studs 81 and is pressed down on the studs by a pair of springs 86 confined between foot member 84 and collars 83. The presser foot has a central 4 vertical opening 86 and has a lower annular foot 87 which is adapted to seat on the work with a pressure which is determined by the strength of springs 86. When plunger 77 moves down, foot 87 moves down with it until the foot seats on the work, and then further downward movement of the plunger applies the pressure of springs 86 to the work.
A cylindric electrode 90 is carried in an adapter 91 which is mounted on the lower face of plunger 77 with interposed insulation 92. An insulating sleeve 93 also surrounds adapter 91 where it passes into and through opening 86 in foot member 84.
In the normal position of the parts electrode 90 5r) lies with its end somewhat inward of the end of foot 87. When pressure is applied to plunger 77 the first operation is to move foot 87 into contact with the work under the pressure of springs 86.
During further movement of plunger 77, and as Co electrode 90 is moved into contact with a tab, the presser foot is maintained against the work under the spring pressure. That foot pressure is thus maintained constant while the pressure which may be applied directly to the electrode (i and to the tab depends upon the fluid pressure which is applied to plunger 77. That electrode pressure is sufficient to press and forge the tab when the tab is heated to a suitable temperature by the applied current. The preferred relationship of size, between a tab and its surrounding recess, and pressure foot 87 and electrode 90, is indicated in Fig. 17. As there shown, the internal diameter of annular foot 87 is larger than the diameter of the recess '60, and the diameter of heating and pressing electrode 90 is also preferably somewhat larger than the recessed diameter, so that the electrode may finally seat on the normal flat surface of the top or bottom plate of the assembled structure at the end .of a securing operation rather than seat in the recess 60. With this provision the tabs can be forged down and flattened to a condition flush with the outer surfaces of the plates, but the head which is formed on the tab cannot easily be reduced in thickness to a dimension less than that which is determined by the depth of recess 60.
The two operating heads 71 are duplicates and are operated simultaneously to apply their pressure feet oppositely to the assembly, and to apply their electrodes simultaneously and under equal pressures to the two opposite tabs of a set. When the electrodes are thus applied the heating current flows in series from one electrode through its contacted tab, and then through the immediately associated plate and the assembled structure in general, to and through the other contacted tab and the other electrode. The heating current and forging pressures are thus applied simultaneously 15 to the two opposed tabs of a pair. ig. 16 shows, merely diagrammatically, a piping system 100 for applying fluid pressure simultaneously to both heads 75 under control of a single valve which is indicated at 101; and also shows diagrammati0 cally the connector strips 102 which connect severally with the electrode adapters 91, and the circuit 103 in which the connectors 102 and the electrodes S9 are connected in series. In an actual practical embodiment of the apparatus, the 5 arrangements are such that foot valve 101 can first be operated to apply the fluid pressure to the heads to first bring feet 87 into opposing contact with the work, and then move the electrodes into pressure contact with the work. Further aca tuation of the foot device then initiates the electric heating cycle. The electrical circuiting and control are such that the heating current is not applied, to the circuit until the circuit is first closed by the electrode making i nitial contact i with the tabs, and the current is then automatically cut off after a time period sufficient for the heating and forging operation to be completed.
Such details however need no illustration or description here, as they form no part of our present invention. In fact we make no claim here to the apparatus of Figs. 16 and 17 in and of itself, only making claim to it as a part of certain method combinations and as involving means for performing the operations which are described.
The finished securings are illustrated in Figs. 13, 14 and 13a. Figs. 13 and 14 show the finished headed form which is taken by a tab 50, and Fig. 13a shows the finished headed form taken by a pair of semi-tabs 51. As shown in Figs. 13 and 14 the heated tab expands transversely in both planes, expanding so as to fill the length of perforation 55 at least in the outer part of the perforation. This expansion is illustrated in Fig. 13 at 50a. The outermost part of the tab also expands in the same direction to form at least a slight heading at 50b beyond the ends of perforation 55. In the direction crosswise of perforation 55 the tab expands laterally, as indicated at 50c to fill at least the outer part of opening 55.
That expansion may extend inwardly of plate edge 62 to fill more of the aperture, but not necessarily so. And outside of the aperture 55, in the recess 60, the tab expands laterally to form a considerable head as shown at 50d. It is not necessary that the heating current be large enough and the-temperature be carried- high enough to cause welding to- take& place- between' the- parts which are-"forced-intto heated contact: By' carrying-the tempera-tues& sufficiently- high, welding- may take place- to some extent, after the tabs: have been expanded into contact with-the plate. But such welding-is -not 'necessary. It is sufficient that the tabs-be--forged into rivet-like: heads which completely and-tightly fill the apertures-and- hich head tightly over the external surface of the 1 The plate is then -held-in solid and tight engagement: with- the edg such as 24; and when this tight-holding securement has been performed for-all of thle? several sets of tabsnthe lont ngitudinal side walls and the 1 transverse- partition walls- acnd the transverse bearings mounting plates, the 'whole-structure- is then so rigidly interconnected that,- although it is entirely made of relatively thin sheet metal, it is virtually an -integrated- structure which is ex- 2 ceptionally rigid -under all the-loads and thrusts to which it may be subjected.
The final form taken by the tabs 51 at gap in partition plate 24, is shown in Pig. 13a.. A transverse section, like that of Fig: 14, of the 2 final form of this tab, would be a duplicate of the showing of Fig. 14. And in the aspect of Fig. 13a the final form is the same. as that shown in Fig, .13,-anmd the same numerals .are applied, except that. the - outer parts of the: two half tabs *; are, forced- together- at-51b, -and, may be-partially welded there or are. at least integrated, so that-the resultant -integrated .whole head is in all essentials like that shown in Fig. 13. To provide the metal for forming the juncture at 51b, the tabs 51 may initially be a little higher than tabs 50; but-those tabs 51 are-in- practice-made of the same height as tabs 50, and the metal for forming that juncture is taken from the lateral overhang of the head (shown in Fig. 14) so that that lateral overhang in the case of tabs 51 may be slightly less than it is for tabs 59.
We claim: 1. An air impeller casing composed of sheet metal, comprising an elongate lower wall plate, an elongate upper wall plate, an intervening vertical wall plate unit contacting the lower and upper plates at its lower and upper edges, said vertical wall unit having a configuration in plan which is substantially rectangularly sinuous and extending longitudinally of the lower and upper plates, and said vertical wall unit forming a series of longitudinally arranged chambers between the lower and upper plates which chambers alternately have open sides at opposite sides of the casing, and a series of substantially identic securing units spaced along the upper and lower edges of the sinuous vertical wall plate unit, each of the substantially identic securing units comprising an integral tab projecting from the edge of the vertical plate through the upper or lower plate and headed over the external surface of that plate.
2. An air impeller casing composed of sheet metal, comprising an elongate lower wall plate, an elongate upper wall plate, an intervening vertical wall plate unit contacting the lower and upper plates at its lower and upper edges, said vertical wall unit having a configuration in plan which is substantially rectangularly sinuous rand extending longitudinally of the lower and upper plates, and having alternating side wall sections and longitudinally spaced transverse partition sections connecting side wall sections at opposite sides of the casing, and a series of substantially identic securing-units-spaced along the upper and lower- edges of the side wall sections -and the partition sections-, each of the substantially identic securing units comprising an integral tab projecting from the edge of the vertical wall unit through the upper or lowerplate- and headed over the external surface of that-plate.
3. An air impeller casing composed-of sheet metal, comprising an elongate lower- wall plate, 0 an elongate upper-wall plate, an intervening-vertical wall plate- unit: contacting 'the-lower and upper -plates at' its lower and upper- edges, said vertical wall unit'having a configuration in plan which -is substantially rectangularly sinuous and extending longitudinallypof:the lo and having alternating-side:wall sections and - longitudinally spaced- transverse partition sections- connecting -side, wall sections at opposite sides -of the casing, and -a series -of substantially O identic securing-units spaced alongthe upper and lower edgles -of the sidewall sections and the partition sections, each of the substantially identic securing- units comprising: an integral tab projecting- from- the -edge- of- the- vertical wall unit .5 through an aperture in the adjacent plate, the plate being externally recessed about the apertureo-and- having- internal :recess bulges which lie at opposite-sides of the. plate edge, and.the tab being-headed over the, external-surface of the 0 plate in the recess.
4. An impeller casing composed-of sheet metal, comprising an elongate'lower wall plate, an elongate upper wall* an intervening vertical. wall plate- unit contacting the lower. and upper 35 plates at-its lower andi-upper edges, said, vertical wall unit having a configuration? in :plan which is. substantially rectangularly' sinuous and extending longitudinally of the lower and upper plates, and having alternating side wall sections and 40 longitudinally spaced transverse partition sections connecting side wall sections at opposite sides of the casing, a plurality of transverse vertical bearing supporting plates arranged in some of the spaces between adjacent transverse parti45 tion sections, said bearing supporting plates having their upper and lower edges in contact with the upper and lower plates, and a series of substantially identic securing units spaced along the upper and lower edges of the bearing supporting 50 plates and the side wall sections and the partition sections, each of the substantially identic securing units comprising an integral tab projecting from the edge of the vertical wall unit through the upper or lower plate and headed over 55 the external surface of that plate.
5. An air impeller casing composed of sheet metal, comprising an elongate lower wall plate, an elongate upper wall plate, an intervening vertical wall plate unit contacting the lower and 60 upper plates at its lower and upper edges, said vertical wall unit having a configuration in plan which is substantially rectangularly sinuous and extending longitudinally of the lower and upper plates, and having alternating side wall sections 65 and longitudinally spaced transverse partition sections connecting side wall sections at opposite sides of the casing, a plurality of transverse vertical bearing supporting plates arranged in some of the spaces between adjacent transverse parti70 tion sections, said bearing supporting plates having their upper and lower edges in contact with the upper and lower plates, and a series of substantially identic securing units spaced along the upper and lower edges of the bearing support75 ing plates and the side wall sections and the par2,442,420 11 tition sections, each of the substantially identic along th securing units comprising an integral tab pro- vertical jecting from the edge of the vertical wall unit identic s through an aperture in the adjacent plate, the projectin plate being externally recessed about the aper- 5 through ture and having internal recess bulges which lie the exter at opposite sides of the plate edge, and the tab 8. An being headed over the external surface of the and in wl plate in the recess, on the v, 6. An air impeller casing composed of sheet 10 vertically metal, comprising an elongate lower wall plate, an 9. An a elongate upper wall plate, an intervening vertical and in wl wall plate unit contacting the lower and upper on the vei plates at its lower and upper edges, said vertical tically op: wall unit having a configuration in plan which is 15 10. An' substantially rectangularly sinuous and being 'and in wl composed of a plurality of substantially identic on the ve sub-units mutually spaced at their adjacent edges vertically to provide drainage passages, and a series of substantially identic securing units spaced along the 20 upper and lower edges of the sinuous vertical wall plate unit, each of the substantially identic securing units comprising an integral tab projecting from the edge of the vertical plate through The foil the upper or lower plate and headed over the ex- 25 file of thi ternal surface of that plate. 25 le 7. An air impeller casing composed of sheet metal, comprising an elongate lower wall plate, Number an elongate upper wall plate, an intervening ver- 1,484,579 tical wall plate unit contacting the lower and up- 30 2,157,441 per plates at its lower and upper edges, said ver- 2,231,063 tical wall unit having a configuration in plan 2,264,897 which is substantially rectangularly sinuous and 2,393,720 being composed of a plurality of substantially identic sub-units arranged in substantially abut- 35 ting relation at their adjacent edges, and a se- Number ries of substantially identic securing units spaced 450,322 e upper and lower edges of the sinuous vall plate unit, each of the substantially ecuring units comprising an Integral tab g from the edge of the vertical plate the upper or lower plate and headed over rnal surface of that plate.
lir impeller casing as defined in claim 1, hich the upper and lower securing units ertical wall plate unit are arranged in opposite pairs.
ir impeller casing as defined in claim 6, hich the upper and lower securing units rtical wall plate unit are arranged in verposite pairs.
air impeller casing as defined in claim 7, hich the upper and lower securing units ertical wall plate unit are arranged in opposite pairs.
FREDERICK C. LINDVALL.
PAUL K. BEEMER.
PAUL H. MONTGOMERy.
REFERENCES CITED owing references are of record in the s patent: JNITED STATES PATENTS Name Date Still ---_--------_ Feb. 19, 1924 Sullivan ___________ May 9, 1939 Evans ----------- Feb. 11, 1941 Becker et al. _------- Dec. 2, 1941 Swanson --_------ Jan. 29, 1946 FOREIGN PATENTS Country Date France ---------_ Jan. 16, 1913
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