US1353797A - Elastic-fluid turbine - Google Patents

Description

'0. STEENSTRUP. ELASTIC FLUID TURBINE.

APPLIGATI'ON FILED FEB. I6, i920.

` Patented Sert. 21,1920

ZSHEETS-SHEET l l' l i HE .M mv

, lvenntor': Chr-is anSLeernstw-up, by n* sTEENsTRuP. ELASTIC FLUID TU RBINE. APPLICATION FILED FEB. I6, I920.

vPatented Sept. 2 SHEETS--SHEET 2- a. o A

I I Inventor: y I

\ Chris imSteenstri-llnk ba. I' {ME/f HIE, Amor-neg CHRISTIAN STEENS'IRUP, OF SCHENECTADY, NEW YORK, ASSIGNOB/,TO GENERAL ELECTRIC COMPANY, A CORPORATON OF NEW' YQRK.- I

,mesmo-FLUID Tunisian.

1,553; roi.

Application filed February 16, 1920. SerialNoi 359,077.

'1'0 all w la om) it may coaccwt:

Beit known that I, CiiinsiriAN SiiinnTn s'iiiur, a citizen'ot the United States` residing at Schenectady, county of Schenectady, Stateof New York, have invented certain new land useful Improvements in Elastic- Fluid Turbines, of which the following is a I specification The: present invention' relates to elasticy i'uid turbines and particularly yto bucket or blade fasteninfr means.

*11n applyingqbuckets to a bucket-carrying element, for example, tothe rim of a turbine wheel, particularly when the Jfastening means is of the so-termed inverted dovetailed type, itis desirable that the adjacent sides of the bucket bases engage each other around the periphery vot the y vwheel so tightly as to set' up stresses in the buckets of such a magnitude that when the wheel is rotating. the centrifugal forces set up will not be sufficient to stretchv the buckets to an eX- tent which would cause the buckets to separate from each other around the wheel. ln other words, it 'is desirable thatthe sides of the bucket bases engage each other with toms ofthe bucket i an improved Suiicient pressure to set up a tension in" the buckets themselves equivalent, at least, lto the stress that will be applied by centrifugal "force when' the machine is in operation. Likewise, it is desirable that the botbases engage the annularA shoulders at the baseof the rim with sufficient pressure, so that the stress set up is equivalent, at least, to the stress that will be applied by centrifugal torce when the inachine iS in operation, so that the bucket bases will not separate from the shoulders. However, it is essential, on the other hand, that initial stresses of too great magnitude should not be set up in the bucket ring when the buckets are being put on the wheel, as this may result in improper positioning of the buckets and in injury to the wheel. and to the buckets. y

The object or my invention is to provide structure and arrangement whereby it is only possible'to set up' initial stresses in thebucket rings of a desired magnitude, and to this end ing stripsl along the edges of the buckets,

' or alongtheir bottoms, or both", which, when the stressesreach a certain value,

I provide crushf Specication ci" Letters Patent. Patent-.ed 21, '1920i` lFor a consideration of whatl believe to be novel and my invention, attentionis directed to the accompanying description and the claims appended thereto.

in the drawing, Figure l is a radial sectional view ott a portion oi aturbine motor having bucket fastening means embodying my invention; Fig. 2 is a' side elevation or' the arrangement showniin Fig. 1; Fig 8 is a section taken on line 3-3 F ig. 1; Figs, 4 and 5 are views similar to Figs.v l-,and 2 of a modiiication, and Figa@ is a radial sectional view of a furthermodiicationj ln Figs. 1, 2 and 3 my invention is illustrated as applied to a bucket structure of the type wherein the bucket-carrying memfV ber 9, shown as being a wheel, hasa rim` lO whiclrisprovided on opposite sides' with. annular concentric undercut grooves providing ridges or projections 1.1 which slope or incline toward the center oi' the n'iein'ber);

At the base oi' rini 10 are shoulders 12. f The:l i

particular type may, according to one known` method, beasseinbled ou the/wheelriiifiby inaking the bucket base legs 14 suthcientlyi, wide apart that-ijshe same may-'be slippedra dially astraddle the rim 10` after which the legs are squeezed together and the buckets are moved radially to bring ridges 1li-and 11 into engagement. According tothis method the entire'ring ot buckets is first-assembled around the wheel in a temporary manner and in correct spaced relation to each other, after whichthe bucket legs of each bucket are squeezed 'or pressed together toward the rim, the Abuckets at the same time) being displaced outwardly, thereby interlocking ridges 11 and 15. Now, during thisrsqueezing up operation, the metal ofthe` bucket base legs 'liows circumferentially `and in some cases this has had the eliect of pressing ad jacent buckets vtogether so tightly that stresses would be set up in the vbucketring the bucket legs are squeezed togethouthe los ridges 15 in moving radially outwardly,

slide up the outer surfaces of ridges 11` and are crushed up by said ridges,

'and the rici tion brought about by this action causes at times, ridges 15 to liow circumferentially and engage so tightly the surta-:es o' the next adjacent buckets as to prevent lthe radial movement of ridges l5 to correct posi tions under ridges 1l. The result is an im perfect interlocking of ridges l5 and t1.

According to my invention, I overcome the above referred to diliiculties by providing crushing strips 16 between the bucket bases which serve to reduce the area oiA contact between adjacent buckets so that rc`A gardless of the amount o'l pressure that may be applied on the sides oi" the buckets, stresses exceeding a predetermined value cannot be set up in the bucket ring since it' such stresses are. exceeded, strips l6 will be crushed. At. the same time, the crushing strips 16 serve to space apart slightly adjacent buckets at the ends oi" the ridges 15 so that even though such ridges do flow cir cumferentially somewhat during the'squcezing-up operation', they will not come into cngagement with adjacent buckets so as to prevent radially outward movement. In other Words, ridges 15 Willjnot liow circumferentially sufiiciently during the squeezing` up operations to frictionally engage, and lock themselves against the next adjacent buckets.

By the provision of such crushing strips, therefore, I am enabled to guard against excessive stresses being set up in the bucket ring when the buckets are assembled utter the manner describedbut still l am enabled to obtain the desired degree of strcssdn the bucket ring. At the same time .l overcome. a serious difficulty which. has hereto'l'ore been encountered in assembling buckets on a rotor by the method re terred to, duc to the ridges kor projections on the bucket legs .flowing sidewise and binding against adjacent bucket surfaces. l

After the bucket legs have been squeezed onto the wheel rim there are small spaces left between the inner end ol' the bucket legs and shoulders l2, and these spaces may be .filled by upsetting the ends ol the bucket legs. or the material of thel shoulders or by driii'ing in a separate calking strip. lin the present instance, the spaces arc shown being filled by a separate calking 'strip 17.

Referring now to Figs. 4l; and 6, an inverted dovetail fastening means is shown ot i thetypc wherein the buckets are put on the rim oi the Wheel through filling slots and moved around into correct spaced relation 'to'each other, the bases olE adjacent buckets vbeing brought into engagement with each other, or with suit-able spacing blocks located between the bucket bases. 2() indicates a bucket wheel having' a rim 2l provided with an annular head 22. which forms projections 23. The buckctslr are provided with U- shaped bases comprising legs 25 which.

straddle rim 2l and have projections 26 which lit under projections 23. At the base ola rim 2l are annular shoulders 2T against which the inner endsI olI bucket legs 25 rest, and at 25 are annular llangcs which prevent tho bucket legs l'rom spreading laterally. lletwccn adjacent buckets are crushing strips )l similar to crushing strips i6 ot ll`igs. l to Il and at the inner ends of the bucket base legs are crushing strips 3l) located between. the bottoms of such legs and iianges 2S.

ln carrying out my invention inv connection with a wheel structure, as shown in Figs. l and 5, l lirst mount the ring of buckets on the wheel rim in the usual manner, the lilling openings being closed by blocks as is well understood. YVhen so assembled, the bucket bases are in nice engagement with each other. I. now take a suitable calking tool and calk a number of the buckets at spaced intervals around the wheel so as to set up a tension in the buckets themselves` equivalent or substan tially equivalent to the stresses that will be applied by centrifugal torce when the machine is in operation. Stresses beyonid a predetermined amount cannotrbe set up in the bucket ring by calking, however, as strips 2S) will be crushed. I also calk the Wheel along the side surtaces of shoulders 27 so as to drive these shoulders out radially and bring projections 26 firmly into engagement with projections ,lfand by utilizing crushing strips il() l avoid the possibility oi setl100 ting up stresses of too great a value in rim 2l and the legs ot thel buckets. During this latter calking operation a small amount of material may be forced up or caused to flow into the spaces between crushing strips 3() 105 as indicated at A in Fig. 5 and this assists in locking the. buckets into position.

Crushing strips 30 may extend either crosswise or circumferentially as found de,-

sirable. ln Figs. 4 and 5 l have shown them 11o as estenihng crosswisc while in Fig. 6 l` have shown a modified arrangement in which they extend circumferentially.

In Fig. 6, 20L indicates the bucket-carry ing member, 24 the buckets, and 29 and 115 30a the crushing strips corresj'ionding to crushing strips 29 and $3() of Figs. 4 and 5. n this connection it will of course be obvious that crushing strips as shown at 30I and 30 in Figs. 4 to 6 inclusive, may be 120 used in connection with a structure as shown in Figs. 1 to 3 inclusive if found desirable.

lln accordance `with the provisions o'l' the patent statutes, l have described the prin- 125 ciple of loperation of my invention y with the apparatus which I n fdvv vonsiuer to represent 'the best 'embodime thereof, but l desire to have it understoodtthat the together .sui .Y i il, apparatus shown 1s only illustiative, and 130 ring having crushing pieces between adia-v cent buckets.

3. In ,anl elastic fluid turbine, a bucketlcarrying memberhaving a rim, and buckets having bases which straddle said rim, said buckets being provided with crushing strips which serve to limit the stresses set up in the bucket ring.

4. In an elastic fluid turbine, a bucketcarrying.' member having a rim with ridges .thereong buckets which straddle said rim and havia ridges which interlock with said 4first named ridges, and integral crushing strips located between adjacent surfaces of the buckets.

5'. In van lelastic fluid turbine having a bucket-carrying member provided with a rim and shoulders, buckets having bases which areattached to said rim and terminate at said shoulders, and crushing strips between the bottoms of the bucket bases and said shoulders.

6. In an elastic fluid turbine having a bucket-carrying member provided with a rim and shoulders, vbuckets having bases which are attached to said rim and terminate at said shoulders, crushing strips between the bottom of the bucket bases and said shoulders, and crushing strips between adjacent surfaces of the buckets.

7'. In an elastic `lluid turbine, a bucket ring 'having buckets provided with crushing strips along their sides and at' their bottoms.

In witness whereof, I have hereunto set my hand.

CHRIsTIAN -s'rniwsra-m

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