US1892930A - Impeller for blowers - Google Patents

Description

Jan. 3, 1933. F, v BURMAN 1,892,930

IMPELLER FOR LowERs Filed Feb. 3, 1930 I/mfeuor @Zim/g?! wumw" 557m Heimweg;

Patentedv dan. 3, 1933 ENT @FWQ FRANK V. BURMAN, OF ST. PAUL, MINNESOTA IMPELLER FOR BLOWERS Application led February 3, 1930.

This invention relates to fans or impellers and has for an object the provision of a simple, highly ecient impeller which is perfectly balanced and centered and which will opcrate noiselessly.

It is a further object of my present invention to provide an impeller of the type having a multiplicity of circumferentially arranged blades wherein the body, fraine and ll@ blades are integrally formed and accurately constructed from a single piece of material.

Most impellers used at the present time for Ventilating systems, oil burners and analogous uses have been objectionably noisy, due

l5 to the fact that the balance and centering have not been perfect. Casting of an integral impeller including the frame and blades has been attempted and has been found entirely unsatisfactory, since the blades and other portions will vary somewhat in thickness and consequently in weight. Many impellers comprise a frame or body and a multiplicity of independent blades rigidly attached to the body. it is practically impossible in such structure to secure all the blades at the same angulation and the same distance from the center, and it is usually difficult to perfectly center the hub with reference to the body. Moreover, independently attached impeller blades, in many instances, become detached from the body or frame of the impeller due to the effect of centrifugal force and are projected through the air with much violence, often causing considerable damage.

A further object of rn invention is to overcome the above noted o jections and to provide an impeller, the body and blades of which are pressed from a single sheet of material, whereby the device will be perfectly 0 centered and balanced and each blade identical in structure and angulation, since all blades are cut and pressed by the same die.

Another object is to provide a comparatively inexpensive and efficient impeller ressed from a symmetrical pan-shaped ody, 'wherein the portions of the body between the several pressed blades will be entirely'unobstructed to permit free passage of a1r.

Another object is to provide a simple effi- Serial No. 425,438.

cient method for making an integral irnpeller of the class above described.

These and other objects and advantages of the invention will be fully set forth in the following description made in connection with the accompanying drawing wherein like reference characters refer to similar parts throughout the several views` and wherein;

Fig. l is a front elevation of the intake of a blower having my impeller mounted therein;

FigQQ'is-a vertical section taken on the line 2 2 of Fig'. i;

Fig. 3 is a detail View showing a fragment of the impeller in front elevation;

Fig. 4.- is a fragmentary side elevation of my impeller detached, a portion of the reinforced and turned outer edge of thebody being broken away; and- Fig. 5 is a side elevation illustrating the step of my method, which consists in longitudinally slitting a symmetrical perfectly centered pan-shaped body.

As shown in the drawing, my impeller is mounted in a conventional blower casing, comprising telescoped shell sections 5 and 6, said shell sections being constructed to afford a spiral passage surrounding the blower and terminating in a discharge 7. The shell sections 5 and 6 are rigidly secured to a base 8 by suitable means, such as a pair of angle brackets 9 and 10, spot-welded or otherwise rigidly connected with base 8 and with the exterior of the shells. Shell member 5 carries a symmetrical converging intake casing 11, which, as shown, is provided with an outwardly projecting annular lip lla. A suitable electric motor M is mounted rear- 4wardly of the shell 6 and secured to base 8 by a bracket 12, the armature shaft 13 of said motor being axiall alined with the intake casing 11 and progecting within the center of the housing formed by shells 5 and 6. My impeller is fixed to armature shaft 13 and disposed substantially centrally of the blower casing and concentrically with the intake casing 11 and directly therebehind.

My impeller is constructed from a single sheet or disc of material, such as sheet metal and the material is first pressed or spun to provided with a perfectly centered circular hub-receiving aperture 14a and a series of relatively small circumferentially spaced attachment apertures (as shown, four in number) surrounding said-hub-receiving aperture. If the body is die-pressed, the base is preferably formed fiat by the die and the hub-receiving aperture and attachment a ertures are precisely positioned and forme by the die in the pressing operation.

The body so formed is next preferably placed on a spinner and the base 14 is spun in the shape of a cone projecting inwardly toward the peripheral edge of the body. During the spinning operation, I also prefer to turn the edge of the body into a reinforcing bead X. -It will,of course, be understood that my lmethod is not limited to the step of spinning the base or die-pressing the body,

but that the pan-shaped body may be formed from sheet material by any suitable means whereby the body is perfectly balanced, symmetrically formed and the hub-receiving aperture perfectly centered.

The pan-shaped body so formed is next progressively rotated and at each rotative step a suitable die slits the body longitudinally from a point adjacent its rim to a point adjacent its base and simultaneously presses inwardly a relatively narrow portion of the stock to form one of the blades 15, the angulation of the blades being determined by the shape'of the die and the width of the blades being determined by timing and actuating mechanism for progressively rotating the .body before each operation of the die. 'llhe blades are of concave-convex cross section with their concave sides disposed inwardly of the body and are so formed in the lstep of my method above described. In the steps of forming the blades, the material at the connected ends of the blades is'drawn by the die so that it will not break or separate but will leave curved webs 15a and 15b at the ends of the blades. The material of the bod is only severed along straight lines exten ing longitudinally of the body and circumferentlally` thereof. After the blades are slit and pressed out, the body may be progressively run through the die again to perfect the shaping of the blades and their inclination.

The portions of the body between two slits are skewed by the die or angled withrespect to the peripheral ed e of the body, and since they are ressed an die-made each one will bea per ect replica of the other.

A hub is formed for thebody and is preferably made on a screw machine to insure perfect symmetry, balance and centering. This hub includes a heavy sleeve which is provided with a" threaded radially extending From the foregoing descri tion it will beseen that a very perfect impel er can be made from sheet material at exceedingly low cost, and that the angulation of the multiplicity of blades, as well as the weight and shape of the blades, will be identical since the impeller is die formed. It further will beapparent that the impeller will be perfectly centered, and

consequently will operate eiliciently and practically noiselessly,` and can never throw a blade.

One of the most important features of my invention is that the body of the impeller is comparatively unobstructed, thereby effecting the displacement of a relatively` great 'amount of air in comparison with other im`` pellers of the Sirocco type. It will be noticed that no material of the vbody extends between the blades nor are the blades provided with any flanges or' other obstructions at their longitudinal edges. This is due to the fact that the blades are slit longitudinall from the material of the body and the sit portions turned on their longitudinal axes, the only connections of said blades with the'body being the webs 15a and 15b at their extremities. As has been stated, the material of the bod is only severed along straight lines exten ing longitudinally thereof and the material is drawn at the ends and no rib or reinforcement member obstructing the passages between the 'blades is necessary to support the y same. The passage of air radially and outwardly of the impeller is only obstructed by the thickness of the sheet material, which is almost negligible.

Due to the structure and advantages above described, my impeller has been found to have much greater capacity and eciency than other sheet-metal impellers -known to me at f this time.

It will, of course, be understood that va'- rious changes may be made in the form, details, arrangementand proportions of the parts without departing from the scope of my invention. What is claimed is:

1. An impeller comprising a symmetrical lrim constructed of sheet metal and with a series of longitudinal slits intermediate its edges, the portions of said rim be tween said slits being bent out of the curve channel in which a set screw is disposed for of said rim providing spaced blades connected rovided renee@ withA the rim only et their ends, the ende of the bent portions between seid longitudinal slits being uncut and drawn in seid bending to form triangular-shaped ends for the blades angled with respect to the mein portions of the blades and bent out of the periphery ot the rim.

2. An impeller comprising e syetricel annular rim constructed of sheet metal and provided with e series ot longitudinal slits intermediate its ends, the entire portions et the material of said rim between seid slits FRANK V. BURR/MN.

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