US2435427A - Turbine wheel - Google Patents

Description

TURB INE WH/EIEL Filed Sept. 16, 1946 2 Sheets-Sheet l I I l I I I I?? @enfer Feb.' 3, 1948. D. P. EAsTMAN i 2,435,427

Y TURBINE WHEEL Filed sept. 16, 1946 2 sheets-smet 2 Fey-5 "75 ggf-w ii I l' 12,3 /ef l l l' l l: I

l fgezf y l daad? 4.51m i? @MM Patented Feb. 3, 1948 UNITED lSTATES PATENT OFFICE TUBBINE WHEEL David 1. `Eastman, Chicago, Ill., asslgnjor to United Specialties Company, Chicago, Ill., a corporation ot Delaware Applieat'ion september 16, 1946, serial No. 697,361

9 Claims. l This invention relates to a turbine wheel and has for one object to secure a plurality of buckets onto the wheel. l

Another object is to secure 'the buckets on a turbine wheel without actually fastening the 6 are 'positionedv two annular members I2. As buckets by welding, braising or otherwise to the shown, some clearance I3 is Yprovided between wheel. these members I2 and the shoulder formed by the Another object is to provide a turbine wheel reduced portion 2. The members I2 are provided with parts which, under the influence of cenwith outwardextensions I4 and cut away portions trifugal force, tend to clamp the buckets tightly to l or clearances I5. `rIhe clearances I5 hold the the wheel. I

Another object is to provide a multi-part turbine wheel with a plurality of buckets, the parts being so arranged that the load of the buckets is distributed between the several parts.

Another object is to produce a Vturbine Wheel suitable for holding buckets 'madeirom-'flat-stock Other objects will appear from time to time throughout the speci'cation and claims.

This invention is illustrated more or less diagrammatically in the accompanying drawings, wherein:

Figure 1 is a section through that portion of the wheel in which the buckets are positioned;

Figure 2 is a side elevation of a bucket;

Figure 3 is a transverse section taken at line 3--3 of Figure 2;

Figure 4 is a plan view of one form of turbine Wheel;

Figure 5 is a section illustrating the Aform of Figure 1 on an enlarged scale and in a modiiied position, after use; and

Figures 6 and '7 are diagrams illustrating the factors which control the design of the bucket holding parts.

Like parts are indicated by like characters throughout the specification and the drawings.

The turbine wheel itself is Vformed lof a'main member I which may be a disc and is preferably reduced, as at 2, and enlarged, asiat 3, to form a peripheral bead or enlargement. The under or inner surfaces oi' the member 3 are inclined, as at 4. Buckets 5 are provided with tongues or extensions 6 which, when .the buckets are in position, embrace the bead 3 and are in contact with the inclined surface-s 4. The ends of the members' are laterally extended as -at 1.

Positioned on either side of the member I and secured to it by rivets 8, or otherwise, are plates 9, 9. Each plate is provided with an inwardly directed portion I0, having 'a depression I I. The members 6 and 1 lie flush against the inner faces of the inwardly bent .portions I0. The shape of the bead 3 and theportions VII! is such thatrl the 2 clearance between 'them is equal to the thickness of the portions 6, 1. n

In the clearance provided between the reduced portions 2 `of the member I and the plates 9 there The modified showing of Figure 5 diiers from I that of Figure 1 only by the change in shape of the portions 1 due to action lof the outer plate members. lAs the wheel is rotated, centrifugal action causes them'embers I2 to move, creep or enlarge, and thusforces the ends of the parts 'I into the depressions I'I The diagrams `of Figures 6 and 7 illustrate on an enlarged 'scale the action which takes place when the members 6,'1'of the buckets are affected by centrifugal force. These diagrams also illustrate the conditions which determine the parti'cular design and angular relationship or shape of the members IIJ and the bead -3 and its inclined surface 4.

For the purposes of this discussion, the members 6, 1 may be considered as comprising iiexible bands. They are anchored at A through the pressure of the weights I2 which press them into the depressions II or otherwise hold them. 4The weights I2 press against the portions 1 of the members S whether the depressions I I and the reduced portions M be provided or not. yIn other words, if the surface of the members I2 were smooth and if the inner. Ysurface of the members Ill were smooth the weights I2 would still press against the members 1 and hold them against the inner surfaces of the members Il).

.The load of the bucket 5 imposes tension, indicated by the letter T1 at the top of Figures 6 and 7. Neglecting, rfor the purposes of this calculation, the eiiect of friction around the bends, there will be an equal and opposite tension T2 at another point B. beyond the rst bend. Thereaction of these two tensions gives rise to a crowding of the membersl against and around the bend on the bead 3 and pressure is thus exerted against the band in the region of this radiusasindicated by the arrows Pin Figures/6 and 7. lThe resultant of all these pressures can be expressed by line R which acts at angle of such a value that R is on the bisector of the angle described by T1 and T2. The resultant R has a vertical component L which is a measure of the amount of pull of the bucket taken by the bead 3.

Figures 6, and 7 differ'only in thedegree of angular separation of T1 and T2; It is obvious. that as the angle between T1 and T2 is decreased as in Figure 7, the angle 0 is increased and the length of R is also increased as may be shown by Vments or extensions I4 bearing against the area .near the ends of the members 1. The outer parts u ilv arerput in place in the positions shown and a a full vector diagram of forces, and L increases both as a result of the increase in magnitude of R, and due to the geometry of the force-triangle here shown.

Load L would be equal to T1 if T1 and T2 were` Load L would be Zero if T1 and T2- 90 apart. were .180 apart. If load L is less than T1, the difference between L andTi is carried by the disc 9. Thus by changing the angular displacement of the surface 4 of the bead 3; and, consequently,

the angular displacement of T2, the bucket load 'suitable number of rivets is tightened in perforations formed in the parts and the wheel is thus held together. c Y Y Y Under the influence of centrifugal force the buckets tend to be distorted, broken or thrown olf the wheel. The shape ofthe wheel parts which engage and contact the bucket members 6, 'I is such as to resist any'displacemient of or damage to the buckets as a result Yof centrifugalforce. Y The portions I0 areA in effectunbalanced orl unsymmetri'cal, each with respect to its. member' 9. Un'derrthe inuence of centrifugal force these i A portions therefore tend not merely to move outnot essential, to cause this pressure of the weight .i

I2 to be exerted close to the base of the flange IIJ, because the flange I0 is in a sense a wealmess. The flange I0 is subject to bending with resulting non-uniform stress of the disc 9. Concen- Y The purpose of the clearance is to prevent jamming of the parts in assembly Vand to make certain that the parts I0 are pressing against the member 2 and the'bead 3. If no such clearance were provided, the parts I and 9 might come in contact prematurely when the wheel is assembled and might thus prevent adequate holding action of the parts I0 on the vbucket members 6, 'I. v

The clearances referred to are minute and usually amount to a Very few thousandths of an inch, but their presence is important and desirable. y* Y The cut away portions or depressions II and I5 vmight be omitted; ,if Ytheywere, the members I2 would have full contact with the portions 1, y andthe portions 'I would be pressed across their lengths in contact with the members I Il. The

provision of the cut away portions or depressions II and I5 is desirable, but the invention is not limited to this feature. j f

It will be realized that, whereas,v I have described and illustrated a practical and operative device, nevertheless many changes may be made wardly, but to rotate with respect to the3p'o`rtions 9 and they thus exertV anY additional pressure which tends to hold the portions 6 Vof'theb'ucket tightly against the bead 3. The parts I0 are also supported by the bead or part 3. The bead 3 thus strengthens the parts I 0 by supporting them and by limiting .their outward movement.V `VThe bead also takes a part of the bucket load since the parts 6, 'lare in part wrapped aroundits corner. The members I2 also tend to be thrown or expanded outwardly under the `iniiuencegof centrifugal force,V and, this causesthem, through Y their portions I4, -to exert an added pressure'upon`Y Y the ends Il of the members Iiandfthus .to force in the size, shape, number and disposition of parts without departing from `the spirit of my invenV tion. u I therefore wish my description and drawings toghe takenas in abroad sense illustrative or diagrammatic, rather thanV as limiting me to my preciseshowing'. i y. Y

LThe Yuse'and operation of thisinvention are as them into ever tighterv engagementrrwith vthe inner surfaces II ofthe members III..Y

The construction of the wheel which has just been described is such that `two means are proff vided for utilizing centrifugal force yto grip andV hold thebuckets in place. yThe greater the speed;

of the wheel the greater is this forceyand thus the tendency of the buckets to leave the wheel Y' under the inuence of centrifugalforce isir'esisted in response to Vcentrifugal force by a 'rela-j Y vtively-slight movement or deformation vofxthe wheel or parts Vof ,thev wheel.V Since the wheel parts are fastened togethenrthfe rmovements;just described arefnecessarilyslight.' Some distortion, displacementor .grow will,however, occur andr experience has Vshown that it does occur.

wheel of the present invention has been designed Vto take advantage of thisV movement or grov'vtli which/would otherwise be a'disadvantage andito utilize it in clamping and holding thebucke'tsY in' place.;

and hold the buckets in place.

Il claim: Y'

wheel member, said member'havingan/enlarged bead at its periphery,V a plurality of buckets Vpc'-YV sitioned on said wheel, said buckets provided'with parts embracing said bead, and a plurality ofV n holding members positioned'one, on eachrside Vof I said wheel member,V said holding VYmembers proa vided Ywith inwardlyiextending parts;V adapted;V Y

under the influenceV of centrifugal force, to grip Forv some purposes and where the wheel is not to be runat great speed., the Amembers I2 might be omitted and themovement of theportions IllV of themembers 9,*under. the .iniluenceof centrifugal'force, will beV found suicient to clamp said bucket parts, and means for holding parts of said bucket ltogether, and additional gripping members positioned between said wheel member and said holding members ,and shaped to contact said bucket members, said additional :members shaped, under the inuence of centrifugal force, to exert an increasing pressure upon said bucket members.

2. In 4combination in aturbine wheel, a main wheel member, said member having an enlarged bead .atits periphery, .a .plurality of buckets positioned on said wheel, said buckets provided with parts embracing said bead and being positioned in close contact therewith, and a plurality of holding members positioned one on each side of said wheel member, said holding members provided with inwardly extending parts adapted, under the iniiuence of centrifugal force, to grip said bucket parts, and means for holding parts of said bucket together, and additional gripping members positioned between said wheel member and said holding members and shaped to contact said bucket members, said additional members shaped, under the influence of centrifugal force, to exert an increasing pressure upon said bucket members.

3. In combination in a turbine wheel, a main wheel member, said member having an enlarged bead at its periphery, a plurality of buckets positioned on said wheel, said buckets provided With parts embracing said bead, and a plurality of holding members positioned one on each side of said wheel member, said holding members provided with inwardly extending parts adapted, under the influence of centrifugal force, to grip said bucket parts, said parts corresponding in contour to the contour of the bucket members which embrace the bead, and means for holding parts of said bucket together, and additional gripping members positioned between said Wheel member and said holding members and shaped to contact said bucket members, said additional members shaped, under the iniiuence of centrifugal force, to exert an increasing pressure upon said bucket members.

4. In combination in a turbine wheel, a main wheel member, said member having an enlarged bead at its periphery, a plurality of buckets positioned on said wheel, said buckets provided with parts embracing said bead, and a plurality of holding members positioned one on each side of said wheel member, said holding members provided with inwardly extending, unsymmetrical parts adapted, under the influence of centrifugal force, to grip said bucket parts, and means for holding parts of said bucket together, and additional gripping members positioned between said wheel member and said holding members and shaped to contact said bucket members, said additional members shaped, under the inuence of centrifugal force, to exert an increasing pressure upon said bucket members.

5. In combination in a turbine wheel, a `main Wheel member, said member having an enlarged bead at its periphery, a plurality of buckets positioned on said wheel, said buckets provided with parts embracing said bead, and a plurality of holding members positioned one on each side of said wheel member, said holding members provided with inwardly extending, unsymmetrical parts adapted, under the inuence of centrifugal force, to grip said bucket parts, said parts corresponding in contour to the contour of the bucket members which embrace the bead, and means for holding parts of said bucket together, and addi- 6 tional gripping members 'positioned between Asaid wllreel member `and'.fsaid'holding members and shaped `to contact said' bucket members, said additional members shaped, funder :the influence of .centrifugal force, to exert lan increasing pressure ,upon -said bucket members.

6. In combination in a turbine wheel, a main wheel member, 4said member having an enlarged bead at its periphery, a plurality of buckets positioned on said wheel, said buckets provided with parts-embracing l.said bead, yand a pluralityfof holding members positioned one on each side 4of said wheel member, said holding members provided with inwardly extending parts adapted, under the influence of centrifugal force, to grip said bucket parts, and means for holding parts of said bucket together, and additional gripping members positioned between said wheel member and said holding members and shaped to contact said bucket members adjacent their ends, said additional members shaped, under the inuence of centrifugal force, to exert an increasing pressure upon said bucket members at their ends.

'7. In combination in a turbine wheel, a main wheel member, said member having an enlarged bead at its periphery, a plurality of buckets positioned on said wheel, saldbuckets provided with parts embracing said bead, and a, plurality of holding members positioned one on each side of said wheel member, said holding members provided with inwardly extending, unsymmetrical parts adapted, under the influence of centrifugal force, to grip said'bucket parts, and means for holding parts of said bucket together, and additional gripping members positioned between said wheel member and said holding members and shaped to contact said bucket members adjacent their ends, said additional members shaped, under the influence of centrifugal force, to exert an increasing pressure upon said bucket members at their ends.

8. In combination in a turbine wheel, ya main wheel member, said member having an enlarged Abead at its periphery, a plurality of buckets positioned on said wheel, said buckets provided with parts embracing said bead, and a plurality of holding members positioned one on each side of said wheel member, said holding members provided with inwardly extending, unsymmetrical parts adapted, under the iniiuence of centrifugal force, to grip said bucket parts, said parts corresponding in contour to the contour of the bucket members which embrace the bead, and means for holding parts of said bucket together, and additional gripping members positioned between said wheel member and said holding members and shaped to contact said bucket members adjacent their ends, said additional members shaped, under the influence of centrifugal force, to exert an increasing pressure upon said bucket members at their ends.

9. In combination in a turbine wheel, a main wheel member, said member having an enlarged bead at its periphery, a plurality of buckets positioned on said wheel, said buckets provided with parts embracing said bead and being positioned in close Contact therewith, and a plurality o1' holding members positioned one on each side of said wheel member, said holding members provided with inwardly extending, unsymmetrical parts adapted, under the influence of centrifugal force, to grip said bucket parts, said parts corresponding in contour to the contour of the bucket members which embrace the bead, and means for holding parts of said bucket together, and addiunder the influence of centrifugal force, to exert 5 an increasing pressure upon said bucket members at their ends.

DAVID P. EAS'I'MAN.v

REFERENCES CITED The following referencesare of record' in the I file of this patent:

Number Number Name n YDate 'Y' Frikart et al. Apr. 9, 1907 Alexander et a1. I 'Apr. '1,1908

FORIQN 'PATENTS Country Date. .s Y

Great Britain 1906 Great Britain Jan. 23; 1913V Austria l rf. 1910

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