US1949679A - Reversing turbine - Google Patents

Description

March 6, 1934- J. H. DORAN REVERSING TURBINE Filed Sept. 50, 1933 Dozlom,

W .W m nnn um e @Q m Two .6 J 9 b 6 Z Patented Mar. 6, 1934 Uisii'ihih TATE REVERSING TURBINE John H. Duran, Scotia, N. Y., assignor to General Electric Company, a corporation of New York The present invention relates to reversing turbines such as are used for ship propulsion, more particularly to the kind of reversing turbines which comprise an ahead part and an astern part exhausting into a common exhaust casing.

With the use of extremely high pressure, high temperature elastic fluid in modern turbine arrangements, particular attention must be paid to the relative expansion caused by the high temperatures between certain parts of the turbines. This applies particularly to the astern or reversing part of a reversing turbine, which part usually comprises a single double-row bucket wheel. The flow of high temperature elastic fluid through this single wheel causes the same to be highly heated and therefore expanded, whereas the massive, heavy shaft and other adjacent members, l ss exposed to the heat of the elastic fluid, are accordingly less heated and expand less than the bucket wheel.

The object of my invention is to provide an improved construction and arrangement of the kind of reversing turbines above specified, particularly with respect to turbines which comprise two shafts, a shaft or drum for the ahead part and a stub fastened to the shaft for carrying the wheel of the astern part.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawing.

In Fig. 1 of the drawing I have shown a sectional View, partly broken away, of a reversing turbine embodying my invention, and in Fig. 2 a cross sectional view along line 2--2 of Fig. 1.

The turbine comprises an outer welded casing 10, a drum or hollow shaft 11 for the ahead part supporting bucket-carrying disks or wheels 12 which in the present instance have been shown as being integrally formed with the drum 11. A diaphragm 13 supported by the casing and packed against the shaft is interposed between adjacent bucket wheels for properly directing the flow of elastic fluid from a higher stage to the succeeding lower stage. The astern or reversing part comprises a stub 14 which has an end portion 15 projecting into and engaging an end portion of the shaft 11. The stub 14 has an intermediate portion defining a collar 16 which with its rear face 17 bears against the end face of the shaft or drum and is fastened thereto by means of axial bolts 18. The reversing part has a double-row bucket wheel including a disk 19 and two rows of buckets 20 and 21 respectively.

The bucket wheel in accordance with my invention is supported by both the shaft and the stub and fastened thereto in such manner that it may expand relatively to the shaft and the stub without setting up undue stresses. This is accomplished by a plurality of circumferentially equally spaced pins projecting through radial holes or bores in the bucket wheel and at least the shaft, or through both the shaft and the stub. To secure uniform expansion and concentric relation between the various parts, it is necessary to provide at least three radial pins displaced at 120 angular degrees.

In the drawing I have shown pins 22 projecting through radial holes in the bucket wheel and the overlapping portions of the shaft and the stub. Each pin is prevented from sliding outward by means of a plug 23 screwed into the hole of the wheel. The reversing part has an inlet conduit 24 for elastic fluid and a diaphragm 25 for directing elastic fluid from the first row of buckets 20 to the second row 21. The casing is packed against the shaft stub by a plurality of packings 26. The outer casing and the first wheel define a chamber 27. A part of the clastic fluid conducted through conduit 24 into the turbine leaks past the entrance side of the doublerow bucket wheel into the chamber 27. To prevent this leakage fiuid from coming into contact with the stub and excessively heating it, I provide in a preferred embodiment the entrance side of the bucket wheel with an inwardly projectin? disk portion 28 which near its inner circumference engages the front face 29 of the collar. The disk portion 28 also reinforces the bucket wheel.

During operation of the reversing part the bucket wheel thereof may expand freely in radial direction. Uniform expansion and eccentric relation between the bucket Wheel, the shaft and the stub are maintained by the radial pins. Excessive heating of the stub is prevented by the inwardly projecting disk portion of the bucket wheel.

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

1. In a reversing turbine, an ahead and an astern part with a common exhaust casing for both, a bucket wheel for the ahead part, a shaft for each part, the shafts having portions overlapping each other, a bucket wheel for the astern part, and at least three circumferentially spaced pins projecting through radial holes in the shaft and the last named bucket wheel for permitting relative expansion and at the same time maintaining concentric relation between said wheel and the shaft.

2. In a reversing turbine, an ahead and an astern part with a common exhaust casing for both, a bucket wheel for the ahead part, a shaft for each part, the shafts having portions overlapping each other, a bucket wheel for the astern part, at least three circumferentially spaced pins sliding through radial holes in the shafts and the last named bucket wheel for permitting relative expansion and at the same time maintaining concentric relation between said wheel and the shaft, and plugs screwed into the holes in the wheel retaining the pins in the holes, the last named bucket wheel having a portion on the entrance side of the reversing part engaging the front face of a shoulder formed on the shaft of the reversing part to prevent elastic fluid from coming into contact with the major portion of said reversing shaft during operation of the reversing part.

3. In a reversing turbine, an ahead and an astern part with a common exhaust casing for both, the ahead part having a hollow shaft and a bucket wheel, the astern part having a stub with a portion seated within the hollow end portion of said shaft and a collar with a rear face engaging the end face of the shaft, a double-row wheel of the astern part being seated on the end portion of the shaft and the circumference of the collar and having a disk portion engaging the front face of the collar, at least three circumferentially equally spaced, radial pins projecting into holes in the shaft and the double row bucket wheel, and axial bolts for fastening the collar to the shaft.

JOHN H. DORAN.

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