US2271971A - Turbine bucket wheel - Google Patents

Description

Feb. 3, H DORAN TURBINE BUCKET WHEEL Filed Feb. 3, 1941 Inventor:

John H. Devan,

His Attorney.

Patented Feb.: 3, 1942 UNITED STATES PATENT OFFICE TURBINE BUCKET WHEEL John H. Doran, Scotla, N. Y., assignor to General Electric Company, a corporation or New York Application February 3, 1941, Serial no. 317,112-

Claims. ((1253-77) accurately machined to form a tight connection with the machined bases of the buckets. The machining of bucket wheels with narrow slots or grooves is diflicult and expensive when theparts are small and require very accurate machining Similarly each bucket I l has a blade 20 and a base 2|. The blades I8. and 20 of the buckets l6 and I1 01' each pair are identical. The bases I9 and 2| of the buckets in accordance with my invention constitute mirror images to each other,

that is, the bases l9 and 2| have the same shape but each base constitutes the image produced by a mirror of the other. Each base has a side 22 which in the assembly is located in a radial plane and a serrated or dovetailed side 23 in intermeshing relationship with one of the serrated sides l4, l5 of a groove. During assembly the pairs of. buckets with their plane surfaces 22 ento get good engagement on both sides of the dovetails.

The object of my invention is to provide an improved bucket wheel or like structure of the type above set forth whereby such structure may.

be readily produced at reduced manufacturing cost.

This is accomplished in accordance with my invention by the provision of a bucket wheel structure in which pairs of separate buckets are held in serrated or dovetailed grooves. In a preferred embodiment the bases of each pair of buckets constitute mirror images relative to each other. In other words, the base of one bucket of such pair is the same or substantially the same as the tion; and Fig. 2 is a modification according to my invention.

The bucket wheel structure in Fig. 1 comprises a disk or like supporting member Ill with an outer rim II for supporting a plurality of buckets l2. The rim has a plurality of axial grooves or slots I3 substantially V-shaped in cross section and with a circumferential width increasing in radial direction of the disk l0. Each g-roove' has two serrated surfaces ll and IS inclined in opposite direction towards the radial plane through the center of the groove. The buckets are arranged in pairs, each pair comprising a first bucket I6 and a second bucket l'l. Each bucket It has a blade l8 and a base I9 gaging each other are inserted axially into the slots l3. An upper portion of each base near the thin edges of the blades forms a projection 24 in engagement with the outer surface 25 of the rim intermediate adjacent slots l3 and with a similar projection of an adjacent bucket.

The arrangement of Fig. 2 comprises a pair of buckets with bases 26 and 21 corresponding to the bases l9 and 2| of a'pair of buckets in Fig. 1. The bases 26, 21 have adjacent surfaces engaging each other. The surface of the base 21 has radially spaced axial grooves or serrations 28 for receiving radially spaced projections 29 formed on the adjacent face of the base 21. Thus the adjacent surfaces of the bases of this pair of buckets are interlocked. v The other surfaces of the bases have serrations or grooves 30 and 3| respectively in intermeshing relationship with corresponding serrations or grooves formed on a disk 32. The buckets may be prevented from axial movement by suitable known means such as peening-over portions of the rim of the disk.

Thus, with my invention I have accomplished :an improved construction of turbine bucket wheels and like structures. Briefly, a bucket wheel structure according to my invention comprises a supporting member or disk with a row of separate buckets secured thereto. Each bucket has a base with dovetailed, grooved or serrated portions in intermeshing relationship with correspondingly dovetailed, grooved or serrated portions of the disk. In the arrangement illustrated the base of each bucket has a width increasing outwardly in radial direction, that is, in the direction towards the blade. In addition, the means for securely connecting the buckets to the disk may also include serrated or grooved portions of adjacent bucket bases in intermeshing relationship with each other. With this in view, a bucket wheel according to my invention comprises a disk with a group or row of buckets viewpoint, a structure according to my invention comprises a plurality of pairs of blades with pairs of bases attached to the ends of the blades.

Opposite surfaces of the bases are inclined in opposite directions with respect to adjacent surfaces thereof. The cross-sectional area of each base increases towards the end of the blade to which it is attached. A grooved supporting member is secured to opposite surfaces of each pair of bases. With this arrangement the center-lines of gravity of the buckets pass substantially through the center portions of the supporting surfaces and with the bucket bases increasing in width towards the blades the latter exert only small bending forces on the bases, thus assuring a rigid construction which may be safely operated at comparatively high load.

Having described the method of operation of my invention, together with the-apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is uily illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a turbine bucket wheel comprising a disk having a rim with a plurality of circumferentially spaced substantially V-shaped axial slots, each slot having a circumferential width increasing of pairs of buckets having blades and separate V-shaped bases with adjacent surfaces of the bases engaging each other and opposite serrated Sing-1088 meshing with the serrated sides of the s o 3. In a turbine, a structure comprising a supporting member having V-shaped slots with serrations in both sides thereof, and pairs of separate buckets each having a blade and a base increasing in width towards the blade with adjacent surfaces of the bases of each pair engaging each other, one of the adjacent surfaces having a groove and the other of the adjacent surfaces having a projection filling the groove, the opposite surfaces of the bases of each pair being inclined in opposite directions towards the adjacent surfaces and having serrations intermesh-- ing with the serrations of the slots.

4. A bucket wheel structure comprising a supporting member having a rim with a plurality of axial grooved slots, each slot having a circumferential width increasing outwardly in radial direction, and a group of buckets each having a base with grooved sides, the grooved bases of each group of buckets filling one of the slots and being arranged in intermeshing relationship with each other and with the grooved slot.

5.. In a turbine, a structure comprising a plurality of pairs of blades, pairs of separate bases attached to the ends of the pairs of blades, adjacent surfaces of the bases of each pair engaging,

each other and opposite surfaces of each pair of bases being inclined in opposite direction with respect to adjacent surfaces thereof, each pair of bases having a cross-sectional area increasing towards the ends of the blades to which they are attached, a support having a plurality of grooved portions, both bases of each pair of bases being disposed in and substantially filling 'the groove of a grooved portion, and means locking opposite surfaces of each pair of bases to opposite surfaces of such groove.

- JOHN H. DORAN.

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