US1778066A - Elastic fluid turbine - Google Patents

Description

Oct. 14, 1930. .1. H. DORAN ELASTIC FLUID TURBINE Filed April 25, 1929 Inventor. John H-DOY-21Y\, b His Attorneg Patented Oct. 14, 1930 UNITED STATES PAT NT? OFFICE JOHN H. nonan, or SCI-IENECTADY, new YORK, As'sren'on To GENERAL ELECTRIC COMPANY, A conronarroivor NEW YORK.

ELASTIC FLUID TURBINE Application filed April 25, 1929: fseriai No. 358,122.

The present invention relates to elasticfluid turbines and particularly relates to a construction of bucket dovetail attaching means which provides for heat expansion.

In turbine practice it is essential to obtain a rigidconstruction of the bucket bases and wheelswhich will withstand not only the stresses set up due to centrifugal action, but

also those Which'occur due to substantial ternperature changes which are continuously going on in the turbine by, virtue of changing conditions of such factors as load and vacuum. Hot steam entering the turbine may cause the ring of bucket bases to increase in circumference much faster than the wheel due to the more direct contact of the buckets with the steam. The bucket bases, as temperature conditions are varied, expand radially, laterally, and endwise. The radial and lateral. ex-

20. pansionsare not material since only single short dimensions are involved. However, the endwise expansion of the bucket bases is accumulative and constitutes the circumferential expansion of the ring or annulus of bases. The endwise dimension involved is the circumference of the ring and as this is large the endwise expansion of several hundred buckets which make up a'ring becomes very material. WVhere the bucket bases form a tight fit there is no room for expansion to take place. As the bucket bases are restricted from expanding circumferentially they f produce heavy forces on the dovetail connections in aradial direction, tending to break the bucket bases or the dovetail lug of the wheel. Breakages usually occur at or near stages where hot steam may initially enter the turbine.

. According to my invention I provide an improved structure and arrangement in a fas- Referring to the drawing, 5 indicates a turbine wheel carrying buckets 6. The base membersof the buckets are indicated at 7. They ar'e' formed with slits which provide legs which straddle the rim of the wheel and engage 1n grooves in: the sides of the rim. This is a known bucketfastening, means termed usually aninverted dovetail. connection.

According to my invention I provide base members 7 with cut-away portions 8 and 9 as shown in the drawing. The cut-away portions 8 are disposed adjacent the center of one end surface of alternate bucket bases 7 forming marginal lugs 10 thereon. The cut-away portions 9 are disposed adjacent to the outer edges of one end surface of the remaining bucket bases forming central lugs 11 thereon.

With the foregoing arrangement, when temperature changes take place during starting or changes of vacuum or load conditions the bucket bases expand into the cut-away portions and also may bow slightly to allow further expansion to take place without breakage. portion disposed adjacent the center of its end surface would bow in the direction of that surface. The remaining bases '7 would bendin the opposite direction.

It is obvious that other means may be employed in carrying out the present invention such as any provision. of bucket bases susceptible of yielding or elastic material in or between said bases.

I therefore do not desire that my invention shall be construed as limited to the specific structural details that are illustrated since they may be modified without departing from the spirit and scope of the invention as set forth in the appended claims.

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

1. In an elastic fluid turbine, a, wheel, a row of buckets having bases attached to the wheel, one-half of said bucket bases being provided with centrally located circumferentially projecting lugs and the other half of said bucket bases being provided with marginal circumferentially projecting lugs, said lugs serving to define spaces between the The bases having the cut-away bases whereby heat expansion of said bases may occur in a circumferential direction.

2. In an elastic fluid turbine, a wheel, a row of buckets having bases attached to said wheel by an inverted dovetail joint, lugs defining spaces between said bases, said lugs comprising central circumferentially projecting base lugs which define one-half of said spaces, and marginal circumferentially pro- 10 jecting base lugs which define the other onehalf of said spaces whereby expansion of said bases may occur in a circumferential direction.

15 arrow of buckets fastened thereon, and lugs disposed intermediate the bases of said buckets, said lugs defining centrally disposed spaces between alternate adjacent base sides and marginally disposed spaces between the 20 remaining adjacent base sides whereby expansion of said bases may take place in a circumferential direction,

In witness whereof, I have hereunto set In hand this 24th day of April, 1929.

25 j JOHN H. DORAN.

3. In an elastic fluid turbine, a wheel with

Images