US2272695A - Centrifugal blower wheel structure - Google Patents

Description

Feb. 10, 1942. A. w. EVANS 2,272,695

CENTRIFUGAL BLOWER WHEEL STRUCTURE Filed May 18, 1940 INVENTOR. ADDISON W. EVANS ATTO EY.

Patented Feb. 10, 1942 CENTRIFUGAL BLOWER WHEEL STRUCTURE Addison Evans, Torrington, Conn., assignor to The Torrington Manufacturing 00., Tori-ington, Conn, a corporation of Connecticut Application May 18, 1940, Serial No. 335,919

9 Claims.

This invention relates to improvements in centrifugal blower wheel structure, and more particularly to an improved arrangement for assembling the cylindrical body structure of a blower wheel, to an associated end ring or back plate thereof, and further providing an improved arrangement for assembling the back plate or end ring to a hub or shaft element.

' With the relatively recent commercial success of those types of centrifugal blower wheels in which the body structure is formed of a single element such as a sheet of metal in cylindrical form, punched and formed to provide parallel centrifugal blades, there has arisen an increased desirability for the use of one-piece punched and formed back plate elements, otherwise sometimes designated as end rings, end plates and the like. In a construction requiring besides a hub, no more than two pieces of metal for its manufacture, viz., the body element and the end ring, the problem arises of producing a sufliciently rigid structure; by this is meant one which will not become misalignedthrough careless handling as when dropped, or when subjected to superposed loading whenshipped or stored in quanties. Other factors tending to effect warping or other deformation, include stresses of operation. It is accordingly a majorpurpose and object of the present invention to enhance the rigidity and permanence of alignment of parts of centrifugal blower wheels of the type noted, without requiring heavier gauges of metal, or increase in weight of finished rotor to attain the result.

Another object of the invention, perhaps of an importance equal to the foregoing object, and related thereto, consists in an improved assembly of hub to end ring,,by which the wheel or rotor as such is better supported onto and by the hub than is the case with the prevailing arrangements in comparable types of centrifugal rotors.

Yet another important object is attained in the provision of an improved assembly feature employed for uniting the peripheral or body portion and the end ring or back plate, the latter termsv being used interchangeably herein, this feature being such that there is provided a continuous, annular truss portion supporting the bladed body over a substantial area inwardly of at least one of its lateral margins, and at the same time endwise bracing and abutting the blades proper in a zone radially inwardly of the cylindrical plane defined by the body.

A further general object may be stated as attained in an improvement in rigidity and maintenance of alignment of the parts of the rotor.

Yet another object of the invention is attained in an improved rotor structure requiring no more than two elements, exclusive of the mounting hub, viz., a back plate element and a body element, each of which may consist of a single piece of stamped and punched material. It will be understood, however, that the improvements herein described in reference to an assembly involving a single back plate or end ring, are equally applicable in many cases to those types of centrifugal blower wheels employing two or some other plurality of rings, rather than a single back plate.

The foregoing and numerous other objects will more clearly appear from the following detailed description of a presently preferred embodiment of the invention, considered in connection with the accompanying drawing, in which:

Fig. l is an end elevation partly broken away, of a centrifugal blower wheel embodying the present improvements, and showing in section certain of the blade elements; Fig. 2 is a side elevation, partly in section, of the rotor of Fig. 1, the sectional portion of'Fig. 2 being taken in a plane parallel to and including the axis of rotation of the wheel; Fig. 3 is an elevation of a portion of the periphery of the wheel or rotor shown by Figs. 1 and 2; Fig. 4 is a fragmentary sectional elevation through one of the groove or rib portions of the end ring or back plate, Fig. 4 appearing as if viewed along line 4,4 of Fig. 1, and Fig. 5 is a fragmentary center section, taken in a plane corresponding to that of Fig. 2, and showing a modified form of hub and hub assembly.

Referring now by characters of reference to the drawing, the example selected for disclosure, being one which'has met with favor in the trade in substantial numbers, includes a body-forming portion of generally cylindrical shape, and which is indicated generally at Ill. The body element lll'is initially comprised of a strip of sheet metal (not shown) which is first punched to provide a series-of parallel spaced lines of incision of the metal, the metal between such lines being turned out of the then fiat or cylindrical plane of the body sheet to constitute a seriesof parallel blades ll. As will be observed, the body In is imperforate beyond the ends of the blades, there reroughly defines the shape of the finished body.

The details of formation of the body strip do not of themselves constitute a part of the present invention, and are more fully described in and covered by Letters Patent No. 2,231,062 issued February 11, 1941, to the present applicant, and entitled Centrifugal blowers.

, It is desirable for continuity and hence rigidity of securement of the body to the end rings, that the body be secured over an uninterrupted annular zone, to the one or more end rings or plates employed, the single end ring or back plate shown as such in the present drawing, being designated generally at l3. An open ring I4 is employed in the example disclosed, to reinforce or stiffen the opposite margin of the body, the arrangement shown being that of a so-called single-inlet type of wheel. It will be understood of course that in wheels of greater axial extent and perhaps of larger diameter, known as double inlet wheels, the end ring structures will both be of sufliciently open construction to permit ready access of the inflow of air to the interior of the wheel.

A preferred mode of securement of the end rings and body is as shown by Fig. 2, involving a radially upturned flange I5 on each of the opposite margins of the body, each flange being received between, embraced by and crimped into permanent engagement with opposite lip portions l6 and I? on the end rings. As a convenient .means for mounting the wheel or rotor on a rotatable shaft or the like, there is provided a special hub, generally indicated at 20, provided with a shaft-receiving bore 2| and a set screw 22. Near one end of the hub is an enlargement 23 of somewhat greater diameter than the major part of the hub, this enlargement being initially formed or machined to provide a frustoconical face 24 which serves, as will later appear, as an inner abutment or seating portion for a correspondingly formed part of the end ring I3. Axially beyond the enlargement 23 the hub is provided with a relatively thin walled extension 25, and as will later appear, the end ring I3 is centrally apertured as at 26 so that its aperture snugly receives the extension 25, the latter being deformed, as by spinning over, the outer extremity of the extension into snug and embracing engagement with the metal adjacent the aperture 26 of the end plate, all as will clearly appear from Fig. 2.

Proceeding now to a description of the improvements identified with the structure of the end ring or back plate such as l3, this element may be and preferably is formed of a single stamped, punched piece of sheet metal of suitable gauge, and the various structural features of the element imparted thereto in a single operation as by suitable dies, as will be apparent to those skilled in the art of press-forming metal members of this kind. The plate or ring, just inwardly of its crimped peripheral portions |6--|'|, is provided with an annular indent portion 30, one wall 3| of which lies substantially ina cylindrical plane so as to constitute a shelf or seat for the circular-planar margins l2 of the body element of the wheel. The portion 3| is importantly fully coincidental with the portion l2, so as completely and continuously to underlie and form a wide support for the lateral margins of the body. The annular groove 30 is further characterized by a bottom portion 32 annular and planar in form, which part, as best appears from Fig. 2, lies in a plane normal to the axis of the wheel and constitutes a relative-.

ly wide end abutment for the blades ll of the wheel and materially coacts with the blades not only in bracing the latter and imparting rigidity referrred to.

, ing indicated at 4|.

thereto, but in reinforcing and strengthening the wheel against deformation.

Inwardly of the planar annular portion 32, the latter is continued into the opposite side of the trough or channel 30, the latter portion being designated at 33. This is somewhat wider than the supporting seat 3|, and is disposed at an angle of about 45 degrees to the plane of the body portion 34 of the plate l3. The length and angularity of the part 33 is such that it serves with portions 32 and 3|, a truss relation which materially improves the support of the body of the wheel and making for improved rigidity of the entire wheel assembly. The annular truss element 33 terminates inwardly, as will appear from Fig. 2, in the planar body 34, the plane of which lies normal to the axis of rotation and normal to the cylindrical plane of the body l|--l2.

At a substantial distance inwardly of the groove or channel 30 is disposed another channel, designated generally at 35, which, similarly to the channel 30, is of angulate section characterized by an outer wall 36, a somewhat wider inner wall 31 and a bottom portion 38. The angulate section of the grooves 30 and 35 has been found superior to a curved section for the purpose of strengthening and reinforcing the plate or ring, as well as providing a more rigid and more permanently shaped wheel.

As will readily appear, the wider side 31 of the annular groove 35 conforms in shape and slope to the frusto-conical face 24 on the hub element 20, so that in assembly the portion 3'! lies snugly against the face 24 which provides a firm and continuous abutment for the matching face portion 31. The frusto-conical face resulting from the shaping of the portion 31 is continued inwardly, i. e., toward the axis of the plate, to form an annular lip ill. The lip 40 is by preference planar in form and results from the formation of aperture 26 in the axial center of the plate |3. It is a distinct preference that the inner edges of the lip 40 be serrated, the serrations be- It has been found in production assembly practice that this serrated formation materially aids in enabling an accurate centering assembly of the hub 20 and plate I3. By disposing these parts in a suitable centering jig or the like, in the event either element fails slightly off of true coaxial relation to the other, such serrations enable a ready and accurate coaxial adjustment. Assembly of the end ring with the body 2 has been heretofore described, and the mode of assembly of the end ring to the hub 20, has been heretofore briefly The latter is completed, after bringing the hub 20 and ring l3 into true coaxial relation, by spinning over the projection 25, so that the latter snugly engages the outer surface of lip 40, and with the body of the hub 20, snugly and permanently embraces this portion of the ring. A further important advantage of the serrations 4|, is found in the fact that the spunover metal of projection 25 extends into the recesses between the teeth portions of the lip 40, thus securely anchoring the back plate to the hub, against angular displacement with respect thereto.

A further highly desirable feature of the end ring structure is found in the provision of any desired plurality, shown as four, of radial ribs or spoke-like portion generally indicated at 50. Each of-ribs 50 is of an angulate, shallow, U- shaped section as best shown by Fig. 4, the parts of the metal struck out from the body 34 to form the channels or ribs, including opposite side walls and 52 and a bottom 53. Each of the grooves or ribs 50, by great preference, merges at its inner end into the annular groove or channel 35, and at its outer end into the annular groove or channel 30; from this it results that each of the ribs extends continuously between the annular channels 30 and 35 so as to provide an uninterrupted stiffening section between the portion 3|, being part of the groove 30, and the frusto-conical seating portion 31 which engages the seat 24 on the hub.

It is a preference that the ribs be formed substantially as shown, namely, of tapering width from their inner ends to their outer ends. conformity is attained principally by varying the width of the bottom portion 53 of each of the radial grooves or ribs, portion 53 substantially vanishing in the zone wherein the ends of the ribs or grooves merge into the outer channel 30. It is a preference also, that the radial ribs or grooves shall be of decreasing depth from their inner to their outer ends.

The annular grooves 39 and 35 and the channel portions 50 resulting in the ribs have heretofore been referred to as recessed portions, chiefly for brevity of description, since their hollowed surfaces are presented outwardly of the wheel. It will appear, however, that when considered from the opposite or inner side of the back plate, each of the portions 30, 35 and 50 may be considered as raised from the plane of the body portion 34 of the plate, thus forming annular projections and true ribs. It will moreover appear from the drawing that the portions 30, 35 and 50 are constituted by instruck or deformed parts of the metal constituting the plate, all projecting in the same direction, i. e. inwardly of the wheel, from the plane of portion 34 of the plate. This is a preference both for structural reasons and for economy in cost of tools utilized in production.

It will have appeared from the description of the features of structure of the rotor, as an advantage that the seat constituted by the element 3| of the outer annular rib or groove 30 constitutes a wide seat for the margins of the body, which seat is radially aligned with the zone of abutment and engagement between the annular frusto-conical part 31 of the back plate, and the similarly conformed portion 24 of the hub. Special mention is herein made of some of the several advantages of providing the angular conforming abutment portions provided by the projection 23 on hub 20, faced as at 24, and the similarly formed part 31. This arrangement aids markedly, both in and after assembly of the wheel, in maintaining the end plate at an exact right angle to the axis of the hub and wheel, besides providing a much stronger bearing for the plate against the hub than is the case in usual arrangements wherein the inner portion of the back plate bears against a planar face portion of the hub along azone normal to the axis of the hub and wheel. As further conducing to rigidity of the wheel and resistance to structural stresses tending to deform the wheel, too much importance cannot be attached to the end abutment for the blades against the element 32. This fact, coupled with the securement of the bladed body at a point radially outwardly from the part 32, provides for engagement of the body and back plate in radially spaced zones, which conduces to rigidity of structure.

In certain assemblies including wheels of the This type described, it is necessary to provide an out side hub, as exemplified by the modified arrangement shown in Fig. 5. This slightly modified form of hub is indicated at 20A, being provided with a shaft bore HA and a set screw 22A. A shoulder 23A has its plate-engaging face undercut at a right angle for engagement with the portion 40 of the end plate l3. In this arrangement a collar or washer 23B is provided with the frusto-conical face 24A engaging the portion 31 of the ring l3, the collar being securely assembled with the central portion of the ring gripped between it and the shoulder 23A, as by the hammered bead or spunover portion 25A. It is noted that the collar or washer 23B serves'as an inside stiffening element against the ring or plate l3, the collar or washer being small enough in diameter to pass through the inlet ring and pass by the inside blade tips. It will be noted that the inside washer arrangement possesses certain advantages on wheels of the larger diameters, and may be utilized on either an inside or outside hub assembly.

It will have appeared from the foregoing detailed description that the finished wheel attained in utilization of the features described, serves fully to realize each and all of the several objects above specifically stated, as well as others implied from the more detailed description.

Although the disclosure has for completeness referred to many preferred details of structure and arrangement, such detail is to be understood in an illustrative, rather than in a limiting sense, since many changes may be made in the parts and their arrangement without departing from the full scope of the invention as defined by the claims hereunto appended.

I claim as my invention:

1. In a centrifugal blower wheel, a cylindrical sheet metal body, an end plate, the end plate being provided with an annular instruck portion near its periphery, forming a seat for the body, means located radially outwardly of the seat and securing the body and end plate in assembly, the body having a margin lying in a circular plane,

the body blades and margin being so proportioned that the annular instruck portion on the end plate, provides an abutment for the blade ends, extending radially and inwardly over a substantial portion of the blade depth.

2. In a rotor for a centrifugal blower, a cylindrical sheet metal body formed to provide a plurality of centrifugal blades, an end plate formed to provide an annular instruck portion near its periphery, said portion constituting a seat for the body, an extension on the outer marginal portion of the end plate, crimped into engagement with an end zone portion of the body, the annular instruck portion constituting a continuous supporting surface immediately adjacent to the body, and further formed to'provide a continuous annular truss portion connecting the body of the ring and the seat for the body, said truss portion extending inwardly of the plane of the end plate, thence along a substantial part of the adjacent end margins of the blades to constitute an end abutment therefor.

3. In a fluid displacement wheel, a back plate of pressed sheet metal, apertured centrally to receive a hub, a bladed body carried by the plate, a hub having an angular plate-seating face, a correspondingly formed seat shaped in the back plate, a thin wall portion of the hub extending through the hub aperture in the back plate, the plate being further provided, just beyond the hub aperture, with cut-away portions, and the thin wall portion of the hub being deformed to en-, gage said cut-away portions, whereby to prevent both axial and angular relative displacement of the plate and hub.

4. In a fluid displacement wheel, a plate of pressed sheet metal having a central hub aperture, a shouldered hub for shaft-mounting the wheel, provided with a relatively thin portion extending through the hub aperture of the plate, and deformed into engagement with the center area of the plate, the metal 01' the plate near the hub being recessed to receive the deformed portion of the hub, whereby to lock the hub and plate against relative angular displacement.

5. In a fluid displacement rotor, a plate of pressed sheet metal, provided with a central hub aperture, a hub for shaft-mounting the wheel, provided with a diametral enlargement angularly laced to form a plate seating portion, the plate being provided with a formed seating portion lying at a distinct angle to the plane of the plate, and conforming to the seating portion on the hub, the metal of the plate being serrated about the hub aperture therein, the hub being provided with a relatively thin wall extension extending through the hub aperture and compressed into engagement with the outer surface of the. plate, so as to coact with the shoulder in embracing the metal of the plate about its hub aperture, the metal of said extension further being compressed into the serrations adjacent the hub aperture, so as to lock the plate against displacement anguiarly with respect to the hub.

6. In a centrifugal blower wheel, a unitary laded sheet metal body, a one-piece back plate having its periphery secured into assembly with one margin of the body, the plate being characterized by formed radial portions providing a plurality of ribs, and further formed to provide an inner annular groove and an outer annular groove, each of said grooves communicating with and merging into the adjacent ends of the ribs, a hub for shaft-mounting the wheel, the hub being provided with a formed face matching in shape, one portion of said inner annular groove of the back plate, and means located inwardly of the annular grooves, for securing the hub and back plate in assembly.

7. In a rotor for a centrifugal blower, a onepiece, bladed sheet metal body, a one-piece back plate having its peripheral portion crimped into assembly with a side margin of the body, the plate being characterized by formed radial portions providing a plurality of ribs and further formed to provide an inner annular groove and an outer annular groove, each of the grooves merging into the adjacent ends 0! the ribs, a hub for shaft-mounting the rotor, the hub being provided with a. formed face matching at least a portion of the inner annular groove, means securing the hub and back plate in assembly, inwardly of the inner annular groove, the outer annular groove extending axially of the body of the back plate, to an extent to constiute a continuous underlying support for the adjacent margin of the body of the rotor, and extended inwardly, or in a radial direction, below the body to constitute an abutment engaging the adjacent ends of the blades over a substantial portion of the blade depth.

8. In a centrifugal blower wheel, a substantially cylindrical one-piece, bladed metal body, a onepiece back plate having its periphery secured to one margin of the body, the plate being characterized by linear, radial instruck portions providing a plurality of ribs of angulate section, and of tapering cross section from their inner to their outer ends, the back plate being further formed to provide an inner annular groove and an outer annular groove, the grooves communicating with and merging into the ends of the ribs, a hub by which the wheel is adapted to be mounted on a shaft or the like, the hub being provided with a frusto-conical plate-supporting lace, and one wall of the inner annular groove being formed to match said face, the hub being provided with an axial extension inwardly of its frusto-conical face, the plate being apertured snugly to receive said extension, and the extension being deformed to overlie, and, with the body of the hub, to embrace the central area of the plate, inwardly of the inner annular groove.

9. In a rotor of pressed sheet metal construction, a plate constituting a web or spider portion of the rotor, and apertured centrally to receive a hub, a hub provided with a relatively thin tubular portion extending through the hub aperture in the plate, the plate being further provided with cat-away portions in the region of the hub aperture, and the thin tubular portion of the hub being deformed to overlie areas of the plate adjacent the hub aperture, and to occupy said cutaway portions, whereby permanently to assemble the plate and the hub and to prevent both axial and relatively angular displacement thereof.

ADDISON W. EVANS.

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