US893077A - Turbine-wheel. - Google Patents

Description

PATENTE I D J. KARRER. D JULY l 1.908 TURBINE WHEEL.

APPLICATION FILED JAN. 15 1907. Fig.2

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JOSEF KARRER,

OF ZURICH, SWITZERLAND, ASSIGNOR TO THE FIRM OF MASCHINENFABRIK OERLIKON, OF OERLIKQN, NEAR ZURICH, SWITZERLAND.

TURBINE-WHEEL.

' Specification of Letters Patent.

Patented July 14, 1908.

Application filed January 15, 1907. Serial No. 352,377.

To all whom it may concern:

Be it known that I, JosEF KARRER, a citizen of'the Republic of Switzerland, residing at Zurich, in Switzerland, have invented certain new and useful Improvements in Turbine-Wheels for- Steam or Gas Turbines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains' to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon,'which form a part of this specification.

This invention relates to a turbine wheel for steam or gas turbines, the blading 'of which consists of blades and distance pieces, or of blades alone,- inserted in dovetail shaped, or other undercut grooves. 1 In such a turbine wheel the blades and distance pieces or the blades or the distance pieces alone, are riveted axially of the rotor. The object of this axial riveting is to obtain a more solid or rigid attachment of the blades than heretofore usual and to prevent the rotor groove walls at their narrowest cross section breaking away.

In order that blades of considerable radial length may be efficiently secured according to this invention in the bottom of .the undercut groove may be out another groove into which the long blades extend and wherein they are secured by axial rivets.

The accompanying drawings show examples of constructional forms of turbine wheels embodying this invention.

Figure 1 is a transverse section through a portion of a rotor and blades. 'Fig. 2 is a vertical longitudinal section. Figs. 3, 4, 5, and 6 are views similar to Fig. 2, showing modifications of peripheral grooves in the rotor. Fig. 7 is a view similar to Fig. 2. Fig. 8 is a view similar to Fig. 1 showing the manner of mounting the blades in rotor periphery shown in section in Fig. 6.

Figs. 1 and 2 show a turbine wheel having a peripheral dovetail-like groove a which is filled up by blades and distance pieces and wherein for example the distance pieces are riveted to the groove walls .9 in the outer portion of the groove which is not undercut at all, by transverse rivets b and the blades are riveted through the walls of the inner dovetail portion of the groove by similar transverse rivets c. ,7

Fig. 3 shows a groove undercut at right angles and Figs. 4, 5 and 6 show under cut grooves of dovetail sha e; in these cases the centrifugal force of the lades is divided into two com onents, the greater component acting radia 1y, exerts a pulling strain upon the rotor groove walls, while the smaller component acts axially and puts a bendin strain upon those portions of the wall whic areof narrowest cross section;'the rivets are for the purpose of taking up this latter or axial strain and thus preventing breaking away at the critical cross section. 1

It will be noted that in all of the figures except Fig. 5, the grooves have a portion 1" or r, in some cases above and in others below the dovetailed portion, the walls of which groove are parallel or nearly so. Fig. 7, also shows a groove 1 having parallel walls at the bottom of the dovetail groove a to serve for the attachment of very long blades as illustrated in Figs. 7 and 8. The distance pieces are mounted in this case in the dovetailed portion of the groove while the roots or shanks of the blades extend beyond the dovetailed portion into the parallel walled portion 0 of thegroove. It is advantageous in such construction to let the radial strain be taken up by the rotor groove walls only. In this case the rivets are only intended to hold the rotor groove walls together and to secure them against breaking away. The radial depth h, Fig. 7, of the groove is not sufficient however, tofix the blades as it is .very small compared with the radial length H -of the effective blade surface. It is for the purpose of increasing the radial depth of the holding portion of the groove that the additional annular groove 1" is turned in the bottom of the dovetail groove a and into whichthe roots of the blades extend. The distance pieces, for example, are riveted into the outer or dovetailed portion of the groove by rivets b and the blades into the inner narrower portion of the groove,to the side walls thereof by rivets c for the purpose of securing the side walls together. The inner narrower groove 1" is also of advantage for blades of smaller. radial depth. The distance pieces and the blades are, it is true, not all exactly equal and are therefore not equally 'well secured; if however there is a groove at the base of the dovetail-like groove, into which the blades and distance pieces do not extend elastic lugs are formed by the side walls of the groove which, by means of the rivets, hold the blades and distance pieces firmly together. By the riveting of the blades it is also possible to entirely omit the distance pieces, as the blades are already fixed by the rivets.

I claim:

1. In a turbine the combination with a rotor having an undercut groove therein; of a comparatively long blade whose root 1S shaped to fit into said groove and rivets transversely through the groove and blade root mounted therein, whereby the centrifugal force exerted on the blade during its rotation and the bending moments set up thereby will be transmitted to the web of the rotor.

2. In a turbine the combination with the rotor having a peripheral undercut groove therein; of two kinds of elements comprising distance pieces and blades mounted in the groove and rivets passing transversely through one of the kinds of elements and the groove.

3. In a turbine the combination with a rotor having a peripheral undercut groove therein; of distance pieces and blades whose shanks are mounted in the groove, and rivets passing transversely through the distance pieces, blades, shanks and grooves.

4. In a turbine the combination with a rotor having a peripheral undercut groove therein; of blades whose shanks aremounted in the groove and distance pieces in the groove alternating with the blades and rivets passing transversely through the distance pieces, blade shanks and groove, those rivets passing through the distance pieces being at a different radial distance from the center of the rotor, than the rivets passing through the shanks.

5. In a turbine, the combination with a rotor having a dovetailed groove therein; of a comparatively long blade whose root is shaped to fit .into said groove and rivets transversely through the groove and blade root mounted therein, whereby the centrifugal force exerted on the blade during its rotation and the bending moments set up thereby will be transmitted to the web of the rotor. v

6. In a turbine the combination with a rotor having a peripheral dovetailed groove therein; of distance pieces and blades whose shanks are shaped to lit the groove, both mounted in the groove and rivets passing transversely through the distance pieces and blade shanks, the rivets passing through the distance pieces being at a different radial dis tance from the axis of the rotor than those passing through the blade roots.

7. In a turbine the combination with, a retor having a peripheral undercut groove therein and a narrower groove cut 111 the wider base of the undercut portion; of blades having shanks fitting said grooves and rivets passing transversely through the shanks and the narrower groove.

8. In a turbine the combination with a rotor having a peripheral dovetail groove therein and a narrower groove cut in the wider base of the dovetail groove; of blades having shanks extending into the narrow groove and rivets passing transversely through the blade shanks and the narrower groove.

9. In a turbine the combination with a retor havin a peripheral dovetail groove therein ant a parallel walled narrower groove cut in the wider base of the dovetail groove; of blades whose shanks fit both grooves and distance pieces in the dovetail groove, rivets transverse to the distance pieces, blade shanks and grooves, those rivets passing through the blade shanks being passed transversely through the narrow groove and those rivets passing through the distance pieces passing transversely through the dovetail groove.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

J OSEF KARRER.

Witnesses:

JosEPn SIMON, E. C. REDINGER.

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