Fan impeller

Aug. 4, 1942.

Μ. H. FR1SBIE

FAN IMPELLER

Filed April 8, 1937

2,292,115

Sheets-Sheet 1

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INVENTOR

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ATTORNEY

Aug. 4, 1942. μ. η. frisbie 2,292,115

FAN IMPELLER

Filed April 8, 1937 2 Sheets-Sheet 2

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ATTORNEY

Patented Aug. 4, 1942

UNITED STATES PATENT OFFICE

2,292,115

2,292,115

FAN IMPELLER

Marshall H. Frisbie, Hamden, Conn., assignor to The A. C. Gilbert Company, New Haven, Conn., a corporation of Maryland

Application April 8, 1937, Serial No. 135,717

Claims. (CI. 170—173)

This invention relates to safety impellers for blades are combined with and extend from the fans and to fan impellers in general in which inside to the outside of the peripheral wall of a hollow shell-like structure surrounding or com- κ prising a central hub.

In safety impellers the blades may be made of relatively soft and flexible material preferably possessing enough resilient stability to maintain a designed curvature and disposition relative to the io hub when stationary and to depart therefrom within only a limited range of deformity as a result of the forces occasioned by rapid rotation. Blades of this character when made of suitably soft material, of which rubber is an example, will 15 yield and collapse upon striking an object even if rapidly rotating, and thus spare the object from damage, immediately reassuming their normal contours and disposition for fanning the air.

An object of the present improvements is to 20 provide blades of this nature by cutting a flat sheet of the blade material to form an annularly continuous central portion with a plurality of blade shapes continuous therewith and radiating outwardly therefrom. This saves the cost of 25 molding special material into the form of individual blades as well as the cost of connecting or attaching separate blades to a common means of support. This cut sheet of material is hereinafter referred to as the blade sheet. 30

Another object is to provide a rigid and hollow central rotor structure for holding the blade portions of the blade sheet in suitably pitched condition and which shall be comprised of the fewest possible number of light weight parts suit- 35 ed for assemblage if desired, without the use of separate fastening means such as rivets, eyelets or screws.

A further object is to provide in the wall of a hollow rotor or hub shell, inclined elongated 40 openings accommodating and imparting pitch to the blades with respect to the plane of rotation, the opposite sides of each such opening being formed by separable edges of the shell wall which edges may be forced toward each other to securely clamp the blades therebetween. Such edges may, if preferred, be rigidly held in definitely spaced relation to form a slot slightly wider than the thickness of the blades for enabling the blades to assume different angles of inclination ⁵⁰toward the front or rear of the impeller with respect to the axis of rotation.

A further object is to form a hollow hub shell from, axially separable cup-like parts whose rims 55 are cooperatively shaped to register and engage while leaving between opposed edges thereof elongated narrow spaces through which impeller blades may extend.

A further object is to provide one of the said cup-like parts with a central lug by which it may be mounted upon the shaft of a fan motor.

A further object is to provide one of the cuplike parts with one or more stud-like projections adapted to engage with one or more perforations in the blade sheet inside the hub shell for centering the blades relative to said shell and to their axis of rotation.

A still further object is to provide removable holding means for determining the axial position of the blade sheet inside the hub shell and for varying such position when desired as an expedient for determining the inclination of the blade surfaces relative to the impeller axis in their portions outside the hub shell.

The foregoing and other objects will appear in fuither detail from the following description of structures by which these objects may be accomplished and in which reference is had to the accompanying drawings wherein:

Fig. 1 is a front view of a fan impeller embodying the present improvements, the lower half of the front impeller cup being broken away to expose the central portion of the blade sheet interior therof, and the developed shape of the blade sheet being indicated by broken lines.

Fig. 2 is a side elevation of the complete impeller of Fig. 1 looking in the direction of arrow A and showing the centrally positioned blade in broken lines to better expose the slotted surface of the blade shell.

Fig. 3 is a fragmentary rear view of the impeller of Figs. 1 and 2 showing the rear wall of the rear shell cup broken away in two locations to expose the interior portion of the blade sheet.

Fig. 4 is a sectional view taken on the plane 4—4 in Fig. 1 looking in the direction of the arrows.

Mg. 5 is a side elevation of the shell cup of Fig. 2 which comprises the rear part of the hub shell structure.

Fig. 6 is a corresponding side elevation of the front shell cup of Fig. 2.

Fig. 7 is a sectional view taken through the developed blade sheet of Fig. 1 on the plane 7—7.

Fig. 8 shows on an enlarged scale one form of retaining member for the blade sheet taken in section on the plane 4—4 in Fig. 1 looking in the direction of the arrows.

. Fig. 9 shows a modified construction of retaining means for the blade sheet taken in section to correspond with Fig. 4.

Fig. 10 is a fragmentary view showing a stop construction for determining the width of the blade slots in the hub shell.

Fig. 7 represents in section a flat blade sheet of resilient flexible material which may be cut to the contours represented in part by the broken lines and in part by the full lines of the blades in Fig. 1. While the material may be metal, Celluloid, or any other flexible substance, in safety fans rubber has been found to be suitable, j Many other substances of correspondingly resilient and non brittle qualities may-be used. The blade sheet as a whole is designated 10. The parts thereof which take the form of blades are designated 11. Blade sheet 10 has the central . aperture 12 or may be otherwise perforated to engage with locating projections inside the hub shell of the present improvements.

A cup-like member 13 comprises the rear portion of .the hub shell structure and in the form shown includes a solid disc which may be cast integrally with a central mounting lug 15 having an axial hole 16 to accommodate the shaft of a fan motor to which it may be secured by the set screw 17. Extending toward the front from the peripheral edge of disc 14 are fin-like projections, flanges or rim portions 18 between which the disc 14 is peripherally notched at 19 to receive projections 20 comprising the rear terminals of the notched wall of the cup-like member 21 which comprises the front portion of the hub shell structure. Thus each of members 13 and 21 possesses walls which extend to the periphery of the hub structure. Projections 20 and equivalents therefor are referred to in certain of the appended claims as “shell sections.”

Members 13 and 21 assemble to make up the hub shell of the present improvements and each may have many cup-like forms other than herein shown. Preferably, however, the hub shell which they combine to form will have an exterior surface of uninterrupted smoothness provided by the matching or registering of the circumferential walls of parts 13 and 21. These walls- may be termed the rim portions of flange-like cup members ! 3 and 21 and the edges of these rim portions may be cooperatively formed so that certain edges 22 of the fins 18 are parallel to the axis of rotation as are abutting edges 23 of the said rim portions formed by cut-outs in the shell wall of member 21.

The inclined edge 24 of the fin-like projections or flanges 18 is shaped correspondingly to the inclined edge 25 of the corresponding notch produced flanges of the walls of member 21, and the dimensions are further such that when members 13 and 2i are assembled as in Fig. 2, a narrow elongated space 26 is left between edges 24 and 25 through which spaces the blades 11 may respectively project.

One or more stud-like inward projections, such as 27 and apart from the hub or mounting lug 15, may be of a size to fit one or more apertures such as 12 in the blade sheet 10 for centering the latter with respect to the hub shell and its axis of rotation. When the central portion of the blade sheet of Fig. 7 is placed over the lug 27, the rear face of the former may be thrust into contact with the front face of disc 14, except for such portions of the blades 11 as are held from so contacting with disc ί 4 by the inclined edges 24. Thus, in Figs. 1 to 4 inclusive, the relatively straight edge 28 of the blade may closely flank the plane of disc 14 throughout its length, whereas the relatively curved edge 29 of and fit the notches 19 in the periphery of 14, after which these rear edge portions at points such as 32 to hold the mem13 and 2! securely together in concentric

2,292,115 blade 11 will be forced forwardly by the arcuate edge 24 of flange 18 thereby establishing the “pitch” of the blade and also determining its normal working surface curvature when the impeller is assembled.

To maintain the central portion of the blade sheet 10 flat against the disc 14, a retaining washer 30 may be employed having centrally extending lock fingers 31 possessing enough spring to press and grab against the lug 27 when forced over the same. The front or nose cup 21 of Fig. 6 may then be forced to its position in Figs. 2 and 4 in which the rearmost edge portions 20 of its flange-like projections respectively engage with and fit the notches 19 in the periphery of disc 14, after which these rear edge portions may be peaned over against the rear surf ace disc ’ bers relationship.

These improvements contemplate the optional use of the structures herein disclosed for solidly clamping the blade sheet between wall edges 24 and 25 or for permitting the blades 11 to pass through the slots 26 more or less loosely as to the fit of the surfaces of the blades 11 in the width of the slots. It is preferable that there shall be no play of the blade longitudinally of the slot for which purpose the width of the blade along the edge of the slot equals the length of the slot causing the assembled peripheral hub walls to embrace both faces and both edges of the blade.

If the flange edges 24 and 25 are not arranged ί to clamp the blades ί I firmly therebetween, a certain control of the shape and position of the blade outside the hub shell may be effected by adjustively shifting the axial position of the center portion of blade sheet 10. Means for doing this are illustrated in Fig. 9 wherein the lug 27' is shown to be externally threaded and carrying two lock nuts 33 and 34 having threaded engagement therewith. A central shoulder 35 on one of these nuts may be of less height than is the thickness of the blade sheet 10 so that the nuts 33 and 34 may jam together in metal-to-metal locking contact while squeezing therebetween the blade sheet 10.

Fig. 10 illustrates a simple expedient for determining a positive width of slot 26 consisting of an eyelid projection 36 punched inwardly from the metal wall of each projection 20 to engage with the front surface of cup disc i 4.

Among the advantages of my improved impeller construction herein proposed are the support of a hollow dome shaped hub housing solely at its rear end of greatest circumference enabling the walls of the cap member forming such housing to be extremely thin and light since for the most part they are required to transmit no rotary power from a motor shaft to the fan blades; the provision of a fully enclosed chamber containing and protecting the central portion of the blade sheet and the inner end of the blades; the edgewise holding of each blade within a wall slot closed at both ends whereby each blade is held as securely for movement in one rotational direction as in the other; the curvature of the blade surface conforming in general to that of the curved surface of a true cone because of the disposition of the blade constraining edges 24 and 25 which imparts a maximum degree of stiffness to any flexible sheet-like body; and the ease and low cost with which any parts of the improved la impeller may be salvaged and used over again in case of defective workmanship or repair.

All of these advantages arise from underlying Principles of construction of which the present examples are but illustrative and the appended claims will be understood as intended to cover all equivalents thereof and substitutes therefor which might be suggested to those skilled in the art by the disclosure hereof.