US2315612A - Turbine shrouding - Google Patents

Description

April 6, 1943. c. c. FRANCK TURBINE SHROUDING' Filed Feb. 14, 1942 a4 23 161: aa'

INVENTOR CLRRENCE C. FRR'NCK.

7b, 0 km ATTORNEY Patented Apr. 6, 1943 TURBINE SHROUDING Clarence C. Franck, Swarthmore, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 14, 1942, Serial No. 430,843

4 Claims.

The invention relates to turbine blading of the shrouded type and it has for an object to provide a shroud construction comprised by overlapping shroud portions formed integral with the blades and riveted together.

A further object of the invention is to provide a shroud construction for a row of blades which is comprised by lapping elements formed integrally with the blade and connected by rivets positioned so as to be subject to minimum bending stresses.

A further object of the invention is to provide a shroud construction for a row of blades which is comprised by shroud elements or portions integral with the blades, each shroud element including spaced tongues or portions extending from the concave face of its blade and disposed adjacent to the side edges thereof and a tongue or portion extending from the convex face of the blade and having a width conforming to and positioned so as to fit between tongues extending from the concave face of the adjacent blade together with rivets for connecting the interfitting tongues, the tongues being so arranged as to avoid overlapping of blade sections thereby.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a sectional detail view showing one embodiment of the invention;

Fig. 2 is a plan view of the shroud construction of Fig. 1;

Fig. 3 is a sectional view taken along the line I III- -III of Fig. 2;

Fig. 4 is a view similar to Fig. 1, but showing a modified form of shroud construction;

Fig. 5 is a plan view of the shroud construction of Fig. 4;

Fig. 6 is a sectional view taken along the line VI-VI of Fig. 5;

Fig. 7 is a view similar to Fig. l, but showin a further modified form of the shroud construction;

Fig. 8 is a plan view of the shroud construction of Fig. '7; and,

Fig. 9 is a sectional View taken along the line IXIX of Fig. 8.

In Fig. 1, there are shown a plurality of blades ID of a row, the blades having root portions 1| arranged circumferentially in contiguous relation. A shroud construction, at 12, is provided for the tips or outer ends of the blades Hi, the shroud construction including lapping portions I4 and I5 formed integrally with the blades, extending circumferentially so as to overlap in tangential planes, and connected by rivets l6 which extend radially with respect to the blade row.

As the rivets l6 extend substantially centrally of the mid-section of the blade passage, they are positioned where th bending moment is a minimum, that is, the rivets are subjected to mini mum bending stresses.

Figs. 4, 5, and 6 illustrate an embodiment wherein the shroud construction at 12a for the blade row is comprised by lapping portions or tongues l8 and a lapping portion or tongue l9 formed as parts of the shroud element 20 integral with each blade Illa. The lapping portions 18 extend forwardly of the concave face of each blade and the portion l9 extends rearwardly of the convex face thereof so that they do not overlap the blade section. The lapping portions l8 extend to the sides of the blade and are spaced so as to receive the portion IQ of the adjacent blade.

The lapping portions l8 and I9 overlap in radial planes and are connected by rivets l6a extending substantially parallel to the axis of rotation.

Aside from the arrangement shown in Figs. 4, 5, and 6 not having any of the lapping portions overlapping the blade sections, whereby cutting of the latter to provide for interfitting of the shroud construction is avoided, this arrangement provides for a relatively strong riveted connection in that each of the rivets ltd acts in double shear.

The embodiment shown in Figs. 7, 8 and 9 is similar to that just described with respect to having the lapping portions overlap in radial planes. It diliers therefrom in that each blade is provided with tongues or overlapping portions 22 and 23 extending in opposite directions, the lapping portions 22 and 23 of adjacent blades overlapping in radial planes and being connected by the rivets lEb extending parallel to the turbine axis. Assuming that the lapping portions or tongues 23 extend rearwardly of the convex faces of the blades, it will be apparent that it is necessary to cut back the shroud element 24 of each blade so that the tongue 23 of the adjacent blade may overlap a portion of the blad section of the first blade, as shown in Fig. 8.

While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is:

1. In a turbine, a rotor, a row of blades connected to the rotor and defining blade passages, and a shroud construction for the blades; said shroud construction including lapping portions formed integrally with the blades and extending from the concave and convex faces of the latter so as to overlap and cover the blade passages and rivets for connecting the overlapping portions, th rivet for the overlapping portions of each blade passage being so located that the stress area effective to connect the overlapping portions is located substantially midway of the width of the blade passage.

2. The combination as claimed in claim 1, wherein the lapping portions overlap in tangential planes and are connected by rivets which extend radially with respect to the rotor.

3. The combination as claimed in claim 1, wherein the lapping portions overlap in radial planes and ar connected by rivets extending substantially parallel to the turbine axis.

4. In a turbine, a rotor, a row of blades connected to the rotor and defining blade passages, and a shroud construction for the blades; said shroud construction including lapping portions formed integrally with the blades, said lapping portions including a pair of spaced lapping portions extending from the concave face of each blade and adjoining the side edges of th latter and a portion extending from the convex face of the blade and arranged to fill the space between the pair of lapping portions extending from the concave face of the adjacent blade and overlap the latter lapping portions, said lapping portions being so formed as to avoid overlapping of sections of the blades and to cover the blade passages, and rivets for connecting the overlapped lapping portions and extending substantially parallel to the turbine axis, the rivet for the overlapping portions of each blade passage being so located that the stress area effective to connect the overlapping portions is located substantially midway of the Width of the blade passage.

CLARENCE C. FRANCK.

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