US2200287A

US2200287A - Turbine

Info

Publication number: US2200287A
Application number: US141388A
Authority: US
Inventors: Lysholm Alf
Original assignee: Individual
Current assignee: Milo AB
Priority date: 1933-02-10
Filing date: 1937-05-08
Publication date: 1940-05-14
Anticipated expiration: 1957-05-14

Description

Mmy14,1940.l A, YSHOLM 2,200,287

TURBINE 'Filed lay 8. 1937 Patented May 14, 1940 UNITEDA STATES 2,200,281 TURBINE Alf Lysholm,

poration of Sweden Application May 8,

Stockholm, Sweden, assignor to Aktiebolaget Milo, Stockholm,

Sweden, a cor- 1937, Serial 'No. 141,388

InfGermany February 10, 1933 9 Claims.` (Cl. 253-39) This application is a continuation in partl with respect to my-copending application Serial No. 710,465, .tiled February 9, 1934.

The present invention relates1to turbines and f has particular reference to turbines intended to ,be operated with motive `iluid of relatively very high temperature. kStill more particularly the invention relates to turbines adapted tobe operated as parts of gas turbine systems and to which 10 motive iiuid is admitted at an initial temperature of at least approximately 800 C. absolute.

When motive fluid is used which has an initial temperature of the labove noted or higher value, difliiculties are encountered in maintaining propy I ler clearances within the turbine and also in maintaining the parts of the turbine rotors as heretoiore constructed in rigidly connected relationship throughout the normal liie of the turbine. Such diilculties are largely traceable to the phenomenon commonly referred to as creep which occurs in the metals usually employed in turbine construction, whenthey are subjected to the combination of mechanical stresses and extremes of temperature which obtain in high temu. peinture-turbines, particularly gas turbines.

'I'he general object of the present invention is to provide improved turbine rotor construction of built-up form which will eliminate or substantially diminish the diiiiculties heretofore encoun- .n teredy in the construction and'operation of turbines of the character under consideration.

In accordance with the invention, the turbine rotor is built up of a number of separate parts including a series of turbine discs to whichV the 35- turblne blades are attached. 'I'he discs are annular in form and the parts of the rotor are welded together atbr near the inner periphery of the annular. discs so as to provide a hollow central shaft portion for the rotor, whichvshaft oh portion includes asan integral part thereof the hub portions of the d iscs. y v

y The discs at the ends of the welded group forming the main part of the rotor are welded to suitable ,end pieces to provide the necessary 45 bearing support for the rotor. 1t will be understood,v oi course, that the construction With respect to end pieces for bearings will vary depending upon the type of rotor, for which the turbine isy intended. Such pieces may be at the ends 50 of the rotor in the case of the usual type of axial iiow rotor having vbearings at its ends for its support. Other typesol" constructions having dierent bearing arrangements are. however,

contemplated within the scope of the invention.

u The invention may be carried into'eiiect'with ,different specific forms of construction, and its `more detailed nature'and the advantages to be derived from its use may best be understood from a consideration of the ensuing portion of this specification and the accompanying drawing in "which are described and illustrated by way. oi

example, suitable forms of rotor construction for vcarrying the invention into eiiect.

In the drawing:

Fig: 1 is a longitudinal central half section, 10 partly in elevation, of a turbine having a rotor embodying the invention in which the hub portions of the rotor discs are welded directly together to form the shaft portion of the rotor;

Fig. 2 is a fragmentary longitudinal central sec- `16 tion of rotor discs directly welded together but oi other form; 'l

F'ig` 3 is a view similar to Fig. 2 but showing still another form of rotor discs welded directly together: and

' Fig. 4 is a viewsimilar to Fig. 2 illustrating still another form of construction embodying the I invention. l l

Referring now toFig. l, thefturbine illustrated is of the axial flow multiple stage reaction type, .y the particular embodiment illustrated `being suitable for use as'a gas turbine adapted to operate at the very high temperatures at which such turbines usually run.

The outer turbine casing l0 is of generally con- .0.

ical form and in the embodiment illustrated, is attached by means of a series of radial pins l2 to an annular supporting member Il which is in turn secured to a second supporting member I6, the latter providing support for the rotor ,5'

bearing I8 at the inlet end of the turbine. An end member 20 attached to the rear end of the casing l0 providessupport for the second rotor bearing 22.

Casing l0 supports a series of stationary blade 0- rings 24, suitably spaced in axial direction to permit the rings of rotor bladesto be inserted therebetween.' The stationary blade ringsmay advantageously be secured to the casing I0 by means of radial pins 26, but ther particular mode 5f 'of mounting the stationary blades is not pertinent tothe present invention or to an understanding thereof.

The rotor comprises a seriesof annular blade carrying discs 28 which at their bases are thick- 50 ened laterally as at 30. The base portions 30 of the discs are permanently secured together by means of welds indicated `at32, and the end discs 28a and 28h are welded respectively to the annular end members 34 and 36 providing the journals 38 and 40 which are supported by bearings i8 and 22, respectively.

As will be evident from the drawing, the thlckened base portions 30, when welded together, form a continuous hollow rotor shaft from which the discs 28 project. This form of shaft not `only produces a relatively light rotor structure, but avoids the possibilityv of parts becoming loosened due to creep of the metal during the life of the turbine. The hollow shaft construction also permits the ready admission of motive uid to the interior of the shaft to aid in obtaining uniform heating and expansion of the rotor when the turbine is started from cold state. l

At the perimeters of the several discs 28 the moving turbine blades 42 are attached. The specific mode of attachment may vary Within the scope of the inventionbut the blades are preferably secured by welding, to provide a completely integral rotor structure. 'I'he joints may be dovetailed as well as welded and as will be appreciated by those skilled in the art, the specific form' of the joint may be in accordance with numerous known methods of attachment.

For purposes ofV illustration, a Vdove-tail or socket joint combined with weldingis diagramf matically indicated at 44.

In the drawing the usualtightening strips are indicated at 46, these strips sewing to minimize leakage between the moving blade discs of thev vv rotor and the stationary bladeringswhichepro- -ject radially inwardly between the rotating discs.

In the form shown in Fig. 2, the construction is the same as in Flg.- 1 in so far"as the general assembly of the rotor is concerned.V In the present instance, however, the discs 28e are provided Y with inwardly projecting ange portions 48 vwhich project radially inwardly from the thickened portions 58 that are welded together as at 52 to form the shaft of the rotor. The inwardly projecting iianges 48 serve to reduce the stresses setup in the discsv due to centrifugal force and are also useful in aligning the separate discs in a jig or the like prior to welding the parts together;

Instead of making full butt welds of the kindv shown in Fig. 2, the hubs of the discs in certain instances may advantageously be shouldered as the size and spacing oi the turbine discs which in some cases may accessible.

In Fig. y4 another form of construction is illustrated in which the discs 28e are not thickened sumciently to permit their being welded directly makea weld 88 relatively into eachother, in which case the hubs of the i discs have interposed between them a series of spacingrings 62. arranged so that the spacing rings and the hubA portions of the discs together form the central hollow shaft portion of the rotor. Y

For ease and accuracy of assembly and welding, the hubs of the discs and the spacing rings are advantageously flanged as indicated at 814 -andy the welds may be made either externally or internally of the rings as indicated at 68 and 68.

In the construction shown in Fig. 4 the rotor may be very readily and comparatively cheaply constructed of rolled plate material, which when of the kind of steel usually required for high temperature rotors, is much less expensive in sheet Y form than in the form of special forgings.

From the foregoing it will be evident that within the scope `of the invention the specinc designs hereinbefore described by way of example may be varied and the invention .fis to be understood as embracing all forms of-'construction falling within the scope of the appended claims.k

What I claim is:

1. For use in elastic huid-turbines, a. build-iup integral hollowl rotor comprisingY a pluralityfof yturbine discs having different blade root diameters and a centralrhollow shaft portion'fsaid discsl being generally symmetrical axially with respectL to' the respective central planes of the discs, said shaft portion being formed by axially abutting parts including the hub portions of said discs and said parts being united by welding, saidshaftl portion constituting the sole means for-retaining Y the discs in axially assembled relation andfthe radially outer portions of sai'ddiscs being Vin `axi-v` s Y kZ5 ally spaced relation. l 4

2., kFor use'in elastic iluid turbines, a build-up integral hollow rotor comprising a plurality of turbine discs of progressively greater blade rootY diameter from the inletto the outlet endl of the" rotor'forcarrying blades providing a generally,v

conical Vpathof flow for expansion of motive u'id, and a central hollow' shaft portion of substantially uniform.A diameter, said discs rbeing 'generg ally symmetrical axially with respect to thefrespective central'plans of the discs, said'shaft portion beingformed byaxially abuttingparts including the hub'portions of said discs and said partsbeing united by, welding, said'shaft portion Y constituting the sole means `for retaining the rotor i parts in axiallyassembled relation4 andthe vradially outer portions of said'discs being inl axially spaced'relation.

3. For use inA elastic fluid turbines, a build-up f integral hollow rotor-comprising va plurality of turbine discs of diierent blade root diameter having hub portions thickened axially on each side of Vthe respectivecentral planesof the discs, to provide discs substantially symmetricalv with respect to-said planes, andacentral hollow shaft portion, said shaft'portion beingformed bythe axially abutting h'ub portions cfy the Vdi'scsjand welds uniting the abutting hub portions,.said4 Vshaft portion constituting the sole means for maintaining the discs in axially assembled 'rela- 1 being in axially spaced relation.

4. For us'e in elasticruidyturbines, a built-up integral hollow rotor cinprisingA a plurality oi' turbine discs having different blade root`diamtion and the radially outer portions of said discsV eters and hub portions thickened'in axial direc- Vtion at each side of the respective central planes of the discs, vto provide discs substantially symmetriCal'With respect to said planes, said hubs having shoulders at their laxially opposite,V sides "to center them with Arespect to axially-*adjacent K hubs ,and said abutting hubs being united `by a welds to form a central hollow shaft portion, said Y shaft portion constituting the sole means*` for y tion and the radially outer portions being in axially 'spacedrelation' `5. For use in elastic iiuid'turbines, a built-up of said discs discs having inner portions Vthickened axially on `maintaining the discs in axially assembled rela.- 1 70;V

`hollow rotor including a plurality of annularV .each side of the respective central planes of the 16" discs, to provide discs substantially symmetrical with respect; to said planes, welds connecting said thickened portions to form a central shaft portion of the rotor, and flange portions projecting inwardly from the thickened portions of the discs, the flange portion and the radially outer portion of respective discs being substantially symmetrically located with respect to the central plane of the disc and the flange portion andthe radially outer portion of respective discs being axially spaced from the corresponding portions of adjacent discs.

6. For use in elastic iluid turbines, a built-up integralV hollow rotor including a plurality of annular discs of increasing diameter axially of the rotor, said discs having hub portions of substantially the same diameter thickened axially on each side of the respective central planesof the discs, to provide discs substantially symmetrical with respect to said planes, welds connecting said thickened portions to form a central hollow shaft portion ofV substantially uniformdiameter axially of the rotor from which the outer parts Aoi' said discs project radially in axially spaced relation, said central shaft portion providing the sole means for Vholding said discs in axially assembled relation, and flange portions on' `of the discs, and a plurality of annular spacing rings interposed between said discs and lwelded to the inner portions of the discs, the inner portions of the discs and said spacing rings providing a central hollow shaft portion for the rotor from which the discs project and the portions of the ldiscs radially outside said shaft portion being in axially spaced relation.y

8. For use in elastic fluid turbines; a built-up hollow rotor having a plurality of annularv turbine discs, said discs being generallyl symmetrical axially with respect to the respective central planes of the discs, and a plurality of annular spacing rings interposed between said discs, the'radially inner portions of said-discs and-the ends of saidr annular turbine discs having dii'lerent blade root diameters and hub portions of substantially the same diameter thickened in axial direction at each side of the central planes of the discs, to

' provide discs substantially symmetrical with respect to said planes, said hubs having shoulders at their axially opposite sides to center them with respect to axially adjacent hubs and said hubs being united by internal and external welds to form a central hollow shaft portion oi' substantially uniform diameter, said shaft portion constituting the sole means for maintaining the discs in axially assembled relation and the portions of said discs outside said hub portions being in axiallyspaced relation.