US1453055A - Centrifugal fan - Google Patents

Description

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F. PHELPS CENTRIFUGAL FAN Filed Aug. 9, 1915 WH'meSSeB:

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the shaft and the IGNon To L. c. n, 'or

application exea aman e, isis. semi in. eases.

Toallwhomtmay concern.' i

it own that l, FRANK Ps, a citieen of the United States, residing at Little Roch, in the county of Pulaski and State of Arkansas, have Vinvented new and useful lmprovements in Centrifugal Fans, ot which the :ibllowing` is a specication, reference being had to the accompanying drawings, forming apart thereof.

The purpose ci this invention is to provide a 'simple and inexpensive type ci construction for a centrifugal fan or blast wheel, such construction beines especially designed to produce a wheel which when adjusted to l a condition oi still balance will also be found to be in satisfactory running balance. llhe usual practice in building blast wheels is to connect the blade with the shaft by means of a comparatively heavy web which is either I formed as a casting or may be built up from standard forms o? rolled steel,such as angles, plates, and the like. 'Whether this web be a cartine or or" auch built-up construction its 1s not perfectly centered when niet mounted' u on the shaft, and the latter is therefore p aced on temporary bearings, and the blast wheel is balanced by either adding weights to the light parts or by drilling out seine oi the-metal in the heavier places until it will stand at rest at any point oi? rotative adjustment on 'its temporary bearings ln this condition the suin of the moments ot all the individual masses which go to make up the wheel is equal to zero when such moments are talrenwith respect to the cris 'of the shaft. `Likewise the algebraic sum of the centrifugal forces or these various individual masses will be zero; but with this usual class oil construction'the centers of mass of the various parte of the wheel will not all lie in exactly the same plane perpendicular to the axis of rotation,-and this is especially true if additional metal has been applied to the wheel at an point for'balancing urposes. The resu t is that although the w eel will appear perfectly balanced so long as it stands at rest, the centrifugal forces set up when the wheel-is revolved and acting edectively in diderent lanes corresponding to the planes in which die centers of avity of the individual partshap en to he, willy produce one or more coup es tending to cause rotation of the wheel and its shaft in.

planes containing the shaft axis. 0f course wheel are restrained 6, of the` other two angles, being against such movement by the hearings balanced couples thus set up tend to cause m which the shaft is mounted, but the unexcessive journal friction on said bearings,

and if they succeed in causing even a very slight bending of the shaft during rotation the elastic ire-action of the shaft to such bending will set up a vibration of the parts which may be transmitted throughout thev entire machine, and which is nearly always detrimental tothe lattere To overcome these difficulties the present invention provides details of construction hereinafter described and shown in' the drawings and which are particularly set out in the appended claims.

in the drawings:

Figure l is anaxial section of a blast wheel and its mounting embodying this invention. Y

Figure 2 is a side elevation of the same with a part ci the casing broken away to reveal 'the construction or the wheel itl.

Figure 3 is an enlarged detail section taken asindicated at line 3--3 on Figure 2.

AFigure d is an enlarged detail section tahen as indicated at line 4 4 on Figure 2.

secured a thin metal dish, 5, which consti-l tutes the web of the wheel. The disk, 5', is cut exactly circular with a central opening to accommodate the hub, 2, and may be somewhat lightened by additional aper-v tures, 5a, punched out ci its area immediately surrounding the hub, 2. Near the eriphery of the dish, 5, are secured the pan blades, 6, and preferably these are arranged in symmetrical fashion projectin from mth faces of the disk, as indicate in the detail section of Figure 3.

Each blade unit is shown as composed of four parts, namely, two angles di osed with their shorter length, 6, oppose and secured together by rivets, 7, fastened to the disk, 5, and with their longer lengths,

t", extending oppositcly atl rlght angles from the disk, 5. The blades thus formed of the angles', 6, are reinforced by additional angles whose opposing` lengths, 8a, are connected by rivets, 9, passing through the web 5, while their other lengths, 8b, are brace against and riveted to the respective parte y hel los' by rivets, l0. lt will be understood that the angles of which the blades are thus composed may readily be formed as stamplng of sheet metal so as to be absolutely uniform in shape and Weight, so that with the vveb, 5, composed of a homogeneous sheet of metal there is little, if anything, in the construction to cause an imperfect balance in the wheel, and so that When itis first placed in temporary bearings it will be found to be very nearly in a condition of still balance. Slight inequalities in the heads of the rivets, 7, 9 and 10, or slight imperfections in the stock of Which the blade is composed may, however, require that a little Work be done on the Wheel to bring it into perfectly balanced condition. Any such imperfections or other slight modiications of the parts to oil-set them, is likely however to result in the distribution of mass centers into more than one transairial plane, so that when the wheel is rotated rapidly there may be set up couples of forces tending to throvv the shaft out of alignment as previously explained. Under this condition however slight, the mass centers of some of the elen ments composing the wheel are not quite in the mid-plane ci the web, 5, but the centril ugal force acting at any one ol these misplaced mass centers being opposed by the radial tension in the web, produces a small resultant force acting transversely of said web and tending to move the individual mass center in such transverse direction to bring thet centrifugal force and the opposing tension into a common line of action. Nowthe web, 5, being composed of sheet metal and being rendered especially flexible by virtue of the removal of a very con siderable portion of the material at apertures, 5a, is adapted to yield to this small transverse force to allow the misplaced mass to assume a position in a common plane with the majority of the individual mass centers of the Wheel; in other Words, any of the blade units Whose mass is not quite symmetrically distributed with respect to the web, 5, is ermitted to shift its position and thereby shiftits center of mass in a direction transverseto the web, 5, and approximately parallel to the axis of the Wheel,-such shifting being permitted by virtue of the flexibility of the disk, 5', by which the blades are carried. Thus While the Wheel is revolving with great velocity the dislr, 5, may be slightly bent or buckled out oi' its nor mal plane at certain parts, but the result Will be an elimination of all couples tending to displace the shalt axis or to exert bending strains upon the shalt.

rlhe casing for this wheel is quite simple in construction being composed of two side plates, il, both centrally apertured and having their apertures reinforced by annular members, l2, which are Z-shaped in cross section. Near the peripheral outline'ol each plate, 11, but slightly set in from such edge there is riveted to the plate a strip, 13, which thus serves as a lian e or shoulder for lodgment of the perip eral casing wall, lll, which is merely a strip of sheet metal of uniform Width laid in position upon the flange members, `13, and held in place by the tie bolts, 15, which transversely connect the side plates, 11, and cross between them just outside the Wall, 14. As indicated in Figure 2, the plates, 11, are cut to form the usual tangent discharge opening at 16, the peripheral Wall, 14, terminating at opposite sides of said opening.

Journal bearings for the shaft, l, are supported in a frame. l?, and the blast wheel casing is also supported on `this traine, 17, partly by means of three bolts,` 18, passing through a central plate, 19, which trictionally engages the web of the annular niembei212. An additional clamp is provided in the form of a. hook bolt, 20, at the upper portion ot said plate which also maintains rictional engagement between the plate and member, 12. rl-he nut of this bolt, 20, is accessible by reaching through one of the apertures, 5a, of the web, 5, it being understood that 'the central aperture in the side plate, ll, which is beyond the end ot the shalt, l, is lett open to serve as an intake for the. air supply to the blast Wheel. Thus, by virtue oll the Wholly irictional engagement between the casing and the plate, 19. of frame, 17, the casing may be rotatively adjusted to bring its discharge mouth, 16, at any angle, upon merely loosening the bolts, 18 and 20.

Since the blade portions, 6b, of the fan wheel are disposed in planes substantially radial to the axis of the Wheel it will be seen that the `wheel may be operated by rotation in either direction. rl`he side plates, 11. et the casing are therefore exactly similar in construction so that by removing the` bolts` 18 and 20. the friction plate, 19, may be completely disengaged from the Z-bar, 12. of the side Wall, il, permitting the casing to be taken apart and reassembled with the plate. 19, in the aperture of the other side wall, 11. rl`hus without any differences of construction the fans built according to this design are adapted to be operated either right-handed or left-handed. Furthermore, the design is so simple that the parts can be shipped in knock-down form and readily assembled by any ordinary mechanic. rThe first element to show signs of Wear is usually the peripheral Wall, 1.4i, but this is very easily renewed by merely removing the bolts, 15, replacing the Wall, 14, with a new strip of sheet metal and again clamping the bolts. 15. into position.

The journal bearings, 21, are shown as lined with the usual bearing metal, 22, and

provided with ring oilers 23, whose operation is Well understood. Both journal boxes are provided with oil filler tubes, 24, and' are formed with oil chambers, 25. surrounding the journal supports, 21. These chambers, however, are connected by a channel. 26, extending through the frame, 17, so that whenever oil is introduced in either of theY filler tubes, 24, it is supplied to both bearings rising to the same level in both oil chambers, 25, by virtue of the connection, 26. The connection, 26. is provided with a discharge openingand a plug, 27. therefor, to be used for draining oft1 the entire supply of o il if desired. A pulley, 28,

` is shown. fixed to the shaft, 1. between the i journal bearings, 21. but it will be understood that any suitable form of power transmission may be employed for driving the wheel.

I claim:

1. In a centrifugal fan, a casing comprising side plates having outwardly facing shoulders on their proximate sides, a peripheral wall member mounted upon said shoulders and spacing the side plates apart, and tie members extending from oneslde plate to the other just outside such periph-l eral Wall and holding the latter in place on the said shouders.

2. In a centrifugal fan, a casin comprising side plates having outwar ly facing shoulders on their proximate sides, a peripheral wall member mounted upon said shoulders and spacing the side lates apart, and removable tie bolts extending through said side plates justv outside the peripheral wall for disengageably holding the plates in position.

3. In the combination of a fan wheel, a shaft and journal bearings therefor, to gether with a casing and a standard adapted to support said bearings and said easing, the casing wall having a central aperture, a plate in the easing overlapping` the edge of said aperture, and clampin bolts extending from the standard throng the plate and within said central aperture for rictionally holding the casing to the standard.-

4. In the combination defined in claim 3, the aperture of the casing being reinforced by a circular member having a flange transverse to the casing wall, and the plate being fitted within said flange to center the casing for rotative adjustment on the standard.

In testimony whereof I have hereunto set

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