US2350739A - Centrifugal fan - Google Patents

Description

June 6, 1944.

r F. FERRE CENTRIFUGAL FAN Filed Aug. 16, 1939 fig 5a INVENTORQ,

FEEDINANDO 1 5mg Brim Z49 ATTORNEYS and compensate for.

Patented June 6, 1944 I oau'rarruoar. ran Ferdinando Fer-n6, Milan, Italy; vested in the Alien Property Gustodian Application August 1c, 1939, Serial No. 290.346

In Italy August 2'1 193s 4 Claims. (01. est-134) This invention relates to centrifugal fans, and has for one of its objects the elimination of the defects ordinarily incident to such fans. As now generally constructed, centrifugal fans are formed with cast rotors, with sheet metal rotors, or with sheet metal parts combined with forged or cast parts.

Fans with cast rotors are objectionable because they are diillcult to maintainin balance at high speeds and also because their speed of rotation is limited, in as much as stresses incident to the relatively great weight of the cast material develops rapidly as the speed increases, whereby the resistant limits of the material is soon exceeded.

The sheet metal fans are objectionable because the various members are connected by rivets or electric welds, which tend to unbalance the rotor in positions and to extents quite difllcult to detect When the sheet metal parts are combined with forged or cast parts, the latter are generally limited to hub or spider parts to which the former are connected by rivets or welds, offering the same objections above noted. In addition, welds often alter the brittleness or other properties of the material, particularly if not properly heat treated, and such heat treatment might itself cause warping. I

The use of centrifugal fans nowadays is extending to increasingly higher temperatures, both for circulation of heated air and for industrial purposes, as ,for heat treatments in which the uniformity of temperature has a particular importance, and may be maintained only by a strong circulation of the air or other heating medium. This is true not merely for relatively low temperatures (under 600 C.) in which-the convection of the heat bears the greatest importance, but also for highertemperatures in which heat radiation becomes more important, since materials are often made in compact bulk and only some of the superficial layers receive the direct action of the radiating heat.

The present invention will in large part ob- 1 viate the above defects.

stamped or machine parts with constant and uniformly distributed weights.

In the attached drawing are shown designs adapted for fans with a single lateral inlet and for a' fan with two axial inlets, wherein 1 Fig. 1 shows a central sectional view through my improved centrifugal fan with a single suction inlet.

Fig. 2 is a similar view of my improved fan ar-' ranged with two axial inlets.

Fig. 3 is a front elevation of the diskon which the fan blades shown in Fig. 1 are mounted.

Fig. 3a is a section taken substantially on the central dotted line of Fig. 3.

' Fig. 3b is a front elevation of the disk on which the fan blades shown in Fig. 2 are mounted.

Fig. 4 is a front elevation of the hub.

Fig. 5 is a plan view, and Fig. 50- an edge view of a fan blade for a single inlet fan, and

Fig. 6 isa plan view, and Fig. 6a an edge view of a fan blade for a double axial inlet fan.

In thedrawing the reference character a designates a supporting disk made of sheet metal and formed with a central aperture surrounded by a series of upset extensions no as shown in blade useable in a single inlet fan, and as best balancing of the fan, both because of the symshown in Figs. 1 and 5 is formed with arcuate feet b and hooks j for purposes presently to be described. As best shown in Fig. 3 the disk a when used, for singleinlet fans is formed with spaced slots (1 of relatively short lengths and spaced radially and circumferentially around the disk. The hOOks j of each fan blade e may be inserted through the slots d of the disk substantially as shown in Fig. 1, and when properly positioned the arcuate feet .b will complete a ring engaging the inner faces of the upset portions a of the disk and the shaft c, a hub member h servingto secure'the assembled fan blades and disk on to the shaft, substantiallyvas shown in Fig. 1. wherein a shoulder on the shaft retains the disk a from axial movement in one direction and the hub his pressed against the opposite face of the disk by threading the nut 1 upon the threaded end of the shaft. Obviously, other methods of securing the disk blades and hub upon the shaft may be utilized.

In the construction of fans with a double axial air inlet, the disk a is formed with radial slots e' extending from the central aperture of the disk into close proximity'to the periphery of the disk substantially as shown in Fig. 3b. Blades m extend through the elongated radial slots e and are formedsubstantially centrally of their outer edges with short slots or notches 12, such slots or notches corresponding in length to the distance between the outer edge of the radial slots e and the periphery of the disk a. The duplex blades m are formed with arcuate feet b, and may be secured upon the shaft in a manner similar to that utilized with the single inlet fan. Thus after each blade m is inserted into its respective slot until its notch palines with the disk, it is then moved radially outward, the diameter of the central aperture in the disk permitting initial positioning and then radial displacement into the positions shown in Fig. 2. When moved into extreme radial position the feet b of the blades m will complete a ring engaging the upset extensions Go of the disk a and the shaft, respectively. Half-hubs k may be utilized for retaining the blades m in position, and a nut l cooperating with a shoulder upon the shaft may be used tohold the fan from axial movement thereon.

The above describes preferred adaptations of my invention and points out the manner in which my invention may be utilized.

I claim: l

1. In a rotor for a centrifugal fan having hub means secured upon a rotatable shaft and a plurality of spaced fan blades projecting radially from said hub means, the combination of a metal disk projecting from said hub means in a plane of which is perpendicular to the axis of said shaft and said disk having a diameter substantially equal to the extreme extension of said fan blades from the opposite sides of the hub means, the fan blades being made symmetrically of sheet metal and having integral intermediate radially disposed portions thereof engaging in slots extending outwardly from the central portion of said disk, so that said blades are 'disposed symmetrically of-said disk in radial planes substantially parallel to said axis of the shaft, and stamped or; bent integral means disposed in the axial direction upon said disk in the portion thereof nearest the shaft and about the same and secured upon said hub means, and there being retaining means disposed upon the inner end of each fan blade at an angle to the general plane thereof for engaging with the hub means.

2. In a rotor for a centrifugal fan having hub means secured upon a rotatable shaft and a'plurality of spaced fan blades projecting radially from said hub means, the combination of a metal disk projecting from said hub means in a plane which is perpendicular to the axis of said shaft and said disk having a diameter substantially equal to the extreme extension of said fan blades from' the opposite sides of the hub means, the fan blades being made of sheet metal and having integral portions thereof engaging in slots in said disk extending radially therein from the central portion thereof, said integral portions on the blades including hook portions lying substantially in the same planes with the blades from which they extend and in a direction substantially parallel to said axis of the shaft, and stamped or bent integral means disposed in the axial direction upon said disk in the portion thereof nearest the shaft and secured upon said hub means, and there being means upon the inner end of each fan blade for engaging with the hub means.

3. In a rotor for a centrifugal fan having hub means secured upon a rotatable shaft and a plurality of spaced fan blades projecting radially from said hub means, the combination of sheet metal disk projecting from said hub means in a plane which is perpendicular to the axis of said shaft and said disk having a diameter substantially equal to the extreme extension of said fan blades from the opposite sides of the hub means, the fan blades being made symmetrically of sheet metal and having integral intermediate radially disposed portions thereof engaging in and extending through radially disposed slots in said disk in substantially the same planes with the blades from which they extend in a direction shbstantially parallel to said axis of the shaft, and integral retaining portions stamped or bent in the axial direction upon the disk adjacent to and secured upon said hub means, and there being retaining means disposed upon the inner end of each fan blade at an angle to the general plane thereof for engaging with the hub means.

4. In a rotor for a centrifugal fan having hub means secured upon a rotatable shaft and a plurality of spaced fan blades projecting radially from said hub means, the combination of a sheet metal disk projecting from said hub means in a plane which is perpendicular to the axis of said shaft and said disk having a diameter substantially equal to the extreme extension of said fan blades from the opposite sides of the hub means, the fan blades being substantially plane, symmetrical sheet metal blades extending through elongated radially disposed slots in the disk from both sides of said disk, said elongated slots extending outwardly from an open central area in the disk occupied by said hub means and dividing the major portion of the disk into a group of segments each of which has a stamped or bent integral retaining means disposed in the axial direction adjacent to and secured upon said hub means, and there being retaining means disposed upon the inner end of each fan blade at an angle to the general plane thereof for engaging with and being retained by the hub means, said hub means having slotted portions for receiving the retaining means of the disk segments and of the blades.

- -FERDINANDO FERRE.

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