US2302437A - Impeller blade with mounting devices - Google Patents

Description

ATTORNEY M. H. FRISBIE.

IMPELLER BLADE WITH MOUNTING DEVICES Filed March 21, 1938 Nov. 17, 1942.

Patented Nov. 17, 1942 DEVICES Marshall H. Frisbie, Hamden, Conn, assignor to The A. C. Gilbert Company, New Haven, Conn., a corporation of Maryland Application March 21, 1938, Serial No. 197,183

7 Claims. (Cl. 170-173) This invention relates to impeller construction involving blades adapted to be rotated by power for producing a flow of fluid medium such as a current of air generated by a household electric fan, or adapted to be so rotated for propelling any movable body on which the impeller is mounted by pressure of the power rotated blades against the fluid medium. The invention also concerns impellers involving vanes arranged on a pivotally mounted hub to produce rotation of the hub responsive to a rate of fluid flow against the vanes as in fluid meters and windmills. The present improvements also relate to novel features of construction in an impeller blade or vane as an article of manufacture and apart from any hub structure on which it may be mounted.

One purpose of these improvements is to provide a simplified means for removably and securely mounting blades or vanes On an impeller hub of the character disclosed in U. S. Patent No. 2,022,417 granted to A. C. Hilbert et al. November 26, 1935, and irrespective of the particular composition or structural make-up of that portion of the blade which works against or responsive to the air or other fluid medium.

A further object is to provide means for so mounting on an impeller hub a sheet-like blade composed of hard or metallic substance, or of rubber or any other soft flexible substance particularly when resilient or not capable when bent or flexed of maintaining designed distortion of its shape, with sufficient rigidity when the blade is fastened to a hub.

A still further object is to produce a composite blade of soft and limber material utilizing a member or members of harder material for imparting to the softer material of the bladebody a designedly warped surface curvature and further for effecting the secure, yet removable, attachment of such a blade to the hub.

Still further objects of the invention are to provide impeller blades, however constituted and mounted on the hub, with novel features of surface curvature combined with novelly contoured edges affording a shape and proportion, and a relationship of a plurality of such blades about a common hub, yielding improved operating efficiency in the reaction of the fluid medium to the movement of the blades.

The above and related objectives will appear more clearly hereinafter and are attained by novel structural features of which examples are set forth in the following description having reference to the accompanying drawing, wherein:

Fig. 1 is a front view of an impeller embodying the present improvements.

- Fig. 2' is a view taken in central vertical section on the plane 22 in Fig. 1 looking in the direction of the arrows showing the central mounting lug inside the hub partially broken away.

Fig. 3 shows a portion of Fig. 2 drawn on a larger scale.

Fig. 4 is a correspondingly enlarged fragmentary view looking into the hollow interior of the hub shell from the rear, or from the right side of Fig. 2.

Fig. 5 is a still further enlarged fragmentary view taken in section on the staggered planes 5-5 in Fig. 4, looking in the direction of the arrows.

Fig. 6 shows the mounting member or strip separated from the softer material of the blade.

Fig. '7 shows the mounting member of Fig. 6 in its assembled relationship to the softer material of the blade, a portion of the latter being broken away or sectioned on the plane 'I'! in Fig. 5.

Fig. 8 is a view like Fig. 5 showing a modification of the construction.

The term rubber is employed in the following description for convenient designation of any suitably soft, flexible and preferably resilient material, of which the main sheet-like body I0 of the blade or vane may be composed. While this body may be of uniform thickness throughout, aswhen its outline is cut from some larger sheet of raw material, its thickness may vary and be configured as desired if the body I0 is produced by molding and setting into suitably toughened condition the material of which it' is composed.

As best shown in Figs. 5, 6 and 7, a thin flat member or strip II of material harder than rubber,

such as pliant sheet metal, may be partially embedded within, and/or bonded to, the softer material of body Ill and preferably in only a marginal portion of the latter. A portion, only, of the total width of strip I I, which may be termed the root margin terminating in a concavely disposed root edge, is left projecting beyond the edge of body I D as a mounting border for the latter.

In the embedded or bonded portion of its width, which may be termed the peripheral margin terminating in a convexly disposed edge, strip I I may contain the perforations I2. One or more preferably T-shaped cut-outs I3 open through the free'edge I4 of member II in a manner to form between such cut-outs the oppositely disposed tongues I6 which extend generally parallel to the free edge M of strip II. The'free'end of each tongue is separated from the adjacent end of a like tongue by the cut-outs I3. While cut-outs I3 are shown in the drawing to comprise an actual cut away of material forming notches having substantial width, this is for purposes peculiar to certain features of the cooperative hub structure and the cut-outs I3 in some cases may comprise mere cuts or breaks in the member I I having little or no width. For additional clinging and holding effect between the materials of body I and member II the notches I I may be formed in member I I and may open into the T-shaped out which separates tongues I6 from the embedded portion of strip I I.

Tongues I6 are free to be independently bent as shown in Fig. 5, straightened again, and then.

rebent-the metal or other material of which strip II is composed being preferably pliant enough to make this possible yet stiff enough to enable each tongue tomaintain firmly any dis torted shape and position into which it may be bent.

From the foregoing explanation of the physical characteristics of the material of the blade body I0 and mounting member II, it will be understood that when these two parts are securely bonded together throughout their contacting surfaces, the relative stiffness of member II presents a strength which will force the marginal portion of body ID to conform thereto. Such bonding is accomplished in well known ways and is suitably accomplished by vulcanizing the rubber of body ID in contact with the brass coated surface ofmember II which latter, for cheapness, may be composed of pliant sheet steel.

If the assembled parts in Fig. '7 be flexed to the arc of surface curvature indicated by broken lines in Fig. 3,member II is preferably stiff enough to maintain this curvature and to hold the marginal portion of body III in conformity therewith. Since all of the normally flat rubber body I0, other than its marginal portion bonded to member II, remains free to seek and assume some less degree of surface curvature nearer its normally flat shape as it extends away from member II, the surface of body II) which is free from member I I may assume a surface curvature conforming to that of the curved surface of a cone. This characteristic of the curvature produced in the free portion of body In is represented by the converging shade lines in Fig. l and results in an increase in pitch of the trailing I end T of the blade if the leading end L of the blade is so disposed that its surface has minimum or zero pitch or inclination in relation to the plane of rotation of the impeller as shown at L in Fig. 3.

The broken lines. in Fig. 5 indicate an interruption in the otherwise overall conformity of the blade surface to the curved surface of a cone which will result when member II, itself, is not flexed to conform to the curved surface of the same reference cone. An arcuately extending hump H may thus result where the free portion of body Ill meets the relatively stiffer marginal portion of body I0. But by flexing member II into conformity with the curved surface of a cone, an overall conical surface conformation may be given to the whole of the blade, or if preferred, the rubber blade surface may be so warped as to form a bowl-like cavity instead of a simple conical trough by flexing member I I to some different shape, such as into conformity with the surface of a cylinder.

' Each blade as a whole may be mounted in upface of the hub shell I8 I6 through slots I9, 20 in the hub shell. While in some constructions, slots I9 and 20 might join and form one continuous slot, slots I9 are here shown as longitudinally aligned with the intermediate slot 20 in the arcuate curve shown in Fig. 3 and spaced endwise from the latter by the uncut portion 2| of shell I8 which is made narrow enough'to enter between the adjacent ends of tongues I6 before any blade fastening bend is made in the latter. When, in the assembly operation, the radially inner or mounting edge of the blade body I which is thicker than the width of slots I9 an 20, has been brought into abutting contact with the outer surface of the hub shell I8 throughout the length of the mounting edge of the blade, the edge 23 of member II containing notches H, which registers with the mounting edge of blade body I6, abuts firmly against the unslotted portion 2| of the hub shell. Thus when tongues I6 are bent into their blade-holding positions inside the hub shell I8 as shown in Figs. 1 to 5, not only the soft material of body II] but also the harder material of member II presses directly and positively against the outside surface of the hub shell and resists the strong inward pulling and wedging action of the inclined top edges 22 of tongues I6 against the inside surface of the hub shell. This wedging action is due to the fact that at and near the root end of tongues IS the space between tongue edge 22 and member edge 23, which contains notches I1, is a little less than the thickness of the wall of hub shell I8, and such wedging action draws the blade edge very firmly against the outer surface of the hub shell throughout its mounted length while the tongues I6, when bent in opposite directions. firmly stabilize the blade in correctly upstanding relation to the surface of the hubshell.

Tongues I6 taper in width from their root ends to their free ends, whereby tongue edges 22, at the free ends of the tongues, are prevented from scraping or binding against the inside of the hub shell as the tongues are being bent for fastening the blades. Thus a concentration of all the wedging action is assured at the most effective holding point, namely, at the root ends of the tongues.

Blade bodies II] are seen to taper radially of the impeller but may be made of uniform thickness throughout. While the embedding of member- I I centrally within the thickness of body In and the abutting of the edge of body I0 against the hub shell combine to conceal the presence of member I I entirely at all points on the outside .of the impeller, it will be understood that where concealment is of no importance, member II may merely overlap one surface instead of both surfaces of body II and be bonded or otherwise securely fastened thereto as shown in Fig. 8. Within the principles of this invention body I0 and member II may be held together in devious ways. Also where there is no need for the blade materialto be softer than the hard material of member I I, this member may be modified so that its entire portion outside the hub shell corresponds to the full area, shape and surface curvature shown in the drawing, as embodied in the rubber body I0, whereby the blade will constitute an integral, instead of a composite, element characterized by the improved fastening means of these improvements.

The number of blade fastening tongues and hub shell slots may be varied at will to suit the circumstance of different numbers, shapes and by inserting the tongues arrangements 'of blades upon a common hub, and many other departures from the particular example of an embodiment of the invention herein illustrated and described will occur to workers in this art. The following claims are intended to define and cover all such departures and all equivalents which come within their terms.

I claim:

1. A composite sheet-like fan blade structure embodying in combination, a sheet of relatively soft and limber material having an arcuate margin terminating in a concavely disposed edge, and a mounting member comprising an arcuate plate of pliant material harder than the material of said sheet having a convexly disposed peripheral edge and a concavely disposed root edge and having a portion of its width between said edges overlapping and bonded to said arcuate margin of said sheet of soft material and having a remaining portion of its said width projecting edgewise beyond said sheet clear of said arcuate margin of the latter.

2. A composite sheet-like fan blade structure embodying in combination, a sheet of relatively soft and limber material having an arcuate margin terminating in a concavely disposed edge, and a mounting member comprising an arcuate plate of pliant material harder than the material of said sheet thinner than said sheet and having arcuate peripheral and root margins and having its said peripheral margin overlapping and bonded to said arcuate margin of said sheet of soft material and having its said root margin projecting edgewise beyond said sheet clear of said arcuate margin of the latter.

3. A composite hub and blade structure embodying in combination with a hub of hard material having slots therethrough, a sheet-like blade of relatively soft material having a mounting margin terminating in a mounting edge, and a member for mounting said blade on said hub comprising a, strip of pliant sheet metal having a portion of its width bonded to said mounting margin of the blade and having a remaining portion of its width extending beyond and free from the material of said body and cut inwardly from its edge most. remote from the material of the said blade in a manner to produce bendable sections shaped and disposed to enter said slots in the hub and to be bent independently of one another for securing said blade to said hub.

in substantially perpendicular relation to said mounting edge and lying in the plane of said marginal portion, and a hub wall perforated to form one or more elongated slots admitting said tongues to the interior of said hub wall, a part of said marginal portion of the fan blade structure abutting against the exterior surface of said hub wall and said tongues being bent respectively on the said spaced lines in a manner to wedge one edge of each tongue against the interior surface of said hub wall, said wedged tongue edge diverging from said hub wall as it extends toward the free end of the tongue.

5. A composite fan blade structure embodying in combination, a sheet-like body of relatively soft material having a mounting edge, and a mounting member comprising a strip of pliant material harder than the material of said body and having a portion of its width bonded to said sheet-like body, the remaining portion of its width being free from said body and terminating in a free edge, said free portion of said strip having at least one T-shaped cut opening through its said free edge in a manner to form separated bendable tongues on opposite sides of said out substantially paralleling the said free edge.

6. A composite fan blade structure embodying in combination, a sheet-like body of relatively soft material having a mounting edge, and a mounting member comprising a strip of pliant material harder than the material of said body and having a portion of its width bonded to said sheet-like body, the remaining portion of its width being free from said body and terminating in a free edge, said free portion of said strip having at least two outs opening through its said free edge so shaped as to form therebetween a T-shaped section of said strip having oppositely extending separately bendable tongues.

'7. A composite hub and blade structure embodying in combination with a hub of hard material having slots therethrough, a sheet-like blade of relatively soft material having a mounting margin terminating in a mounting edge, and a member for mounting said blade on said hub comprising a strip of pliant sheet metal having a portion of its width bonded to said mounting margin of the blade including an edge having notches filled with said soft material, and having a remaining portion of its width extending beyond and free from the material of said body and divided into separated bendable sections shaped and disposed to enter said slots in the hub and to be bent independently of one another for securing said blade to said hub.

MARSHALL H. FRISBIE.

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