US3565547A - Turbomachine rotor construction - Google Patents

Abstract

A ROTOR WHEEL FOR USE IN A TURBOMACHINE WHEREIN THE CIRCUMFERENTIALLY ARRANGED BLADES ARE PROVIDED WITH EXTERNALLY THREADED SHANK PORTIONS FOR MATING WITH INTERNALLY THREADED OPENINGS PROVIDED WITHIN THE SUPPORTING DISC. INTERMEDIATE PORTIONS OF ALL BUT TWO BLADES HAVE AT LEAST ONE PERIPHERAL SECTION REMOVED WHILE ONE OF THE REMAINING TWO HAS NO REMOVED SECTION AND THE OTHER HAS TWO SHANK SECTIONS REMOVED SO AS TO PERMIT SEQUENTIAL ASSEM-

BLY OF THE BLADE IN A CIRCUMFERENTIAL PATH ABOUT THE DISC IN A PREDETERMINED MANNER.

Description

Feb. 23, R, E HANSEN TURBOMACHINE ROTOR CONSTRUCTIOS Filed Feb. 24, 1969 INVENTOR. RAYMOND E. HANSEN.

ATTORNEY.

United States Patent 3,565,547 TURBOMACHINE ROTOR CONSTRUCTION Raymond E. Hansen, New Alexandria, Pa., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Feb. 24, 1969, Ser. No. 801,687 Int. Cl. F01d /32 US. Cl. 416204 2 Claims ABSTRACT OF THE DISCLOSURE A rotor wheel for use in a turbomachine wherein the circumferentially arranged blades are provided with externally threaded shank portions for mating with internally threaded openings provided within the supporting disc. Intermediate portions of all but two blades have at least one peripheral section removed while one of the remaining two has no removed section and the other has two shank sections removed so as to permit sequential assembly of the blade in a circumferential path about the disc in a predetermined manner.

BACKGROUND OF THE INVENTION In a turbomachine such as a turbine or axial-flow compressor, fluid under pressure is directed against an annular array of blades or buckets disposed about the periphery of an annular support member secured to a power shaft. The fluid subjects the blades to severe vibrational stress and also in some instances stress due to thermal gradients imposed across the assembly as it strikes successively arranged blades from a substantially tangential direction. More importantly, rotation of the wheel sets up centrifugal forces which tend to throw the blades out from the wheel. These forces are ordinarily restrained by special attachments requiring expensive machinery, such as T-slots or pine-tree roots. In the present invention, a simple inexpensive screw-thread is substituted for these special root forms. It is extremely important that the individual blades be securely affixed to the support member in order to avoid destruction of the machine should one or more of the blades become loose during operation.

SUMMARY OF THE INVENTION This invention relates to an improved wheel particularly with regard to the manner in which the individual blades are assembled and secured to the outer peripheral surface of their associated annular support or disc.

In accordance with the invention, the annular supporting disc is provided with a plurality of circumferentially spaced tapped openings. The blades to be assembled with the disc each include an externally threaded shank portion so that the blade can be readily assembled with the tapped opening in the disc. In addition to the shank, there is provided a body portion having a cross-sectional configuration in the form of an airfoil as is generally known in the art. Located intermediate the body portion and the shank portion is a relatively thin flat circular section integrally formed with the blade and referred to hereinatfer as a platform. In order that the individual blades may be assembled and be maintained against relative movement insofar as the disc is concerned, the circular platform portion has in most instances an arcuate edge section removed so as to provide a relief. The first blade assembled with the disc is provided with opposed arcuate reliefs. The next adjacent blade is provided with a single relief as are each of the succeeding next adjacent blades until the last blade is ready for assembly. The last blade does not have an arcuate relief and serves to lock the cir- 3,565,547 Patented Feb. 23, 1971 cumferential array of blades in tight engagement, free from relative circumferential movement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an impeller wheel, in perspective, constructed in accordance with this invention;

FIG. 2 illustrates the arrangement of a portion of the individual blades relative to one another upon assembly with a rotor; and

FIG. 3 is a partial, fragmentary view in perspective of three blades constructed in accordance with this invention prior to their assembly with a supporting disc.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings for a description of one form of the invention, there is provided a Wheel 10 of the type employed with turbomachines such as turbines utilizing water steam or gas as an input fluid. As is well known in the art, the energy present in the input field is converted to mechanical energy through the rotation of the impeller wheel under the influence of the stream of fluid being brought into contact, through nozzles, with the individual blade members arranged about the periphery of the wheel. It will be appreciated the wheel is attached to a shaft which in turn is attached to a device utilizing the mechanical energy provided. Inasmuch as this invention is directed to the impeller wheel employed in turbomachines it is not necessary to illustrate and describe the other components of the machine such as the casing, nozzle assembly, steam chest, or controls, all of which are well known in the art.

It is extremely important in turbomachinery of the kind described that the blades be securely mounted to the periphery of the wheel. The present invention is directed to a blade configuration which readily lends itself to a secure connection with the supporting disc. The disc 11 is provided with a plurality of circumferentially spaced radially extending tapped openings 12 extending inwardly of the impeller wheel from the outer peripheral surface. The openings are in turn provided with a counterbore 13 for a purpose to be later described.

Arranged within the tapped openings are blade members 14 illustrated in detail in FIG. 3.

Referring more particularly to FIG. 3, each blade 14 is provided with an externally threaded shank portion 16 and a body portion 18 arranged to extend within a passage in the machine through which the high energy fluid flows during operation of the machine. Disposed intermediate the body portion 18 and the threaded shank portion 16 is a circular platform portion 20. The platform 20 is provided with a shape enabling it to be received within the counterbore 13 so as to provide a step-free surface, in the interest of more efficient fluid flow.

In accordance with the invention and with two exceptions, as will be more clearly apparent, at least one arcuate edge section is removed from each platform 20 so as to provide a relief. In one instance it is necessary to provide at least one of said blades 14a with opposed reliefs. In a second instance one of the blades 14b is unrelieved.

Considering the operation of the invention when it is desired to assemble the blades with the disc in order to provide a wheel for use in a turbomachine, the blade 14a having the opposed arcuate cut out sections or reliefs is initially assembled with an opening in the disc, not FIG. 2. Thereafter, a blade '14 having a single arcuate relief is mounted within an opening adjacent that accommodating the first blade. The arcuate relief section on blade 14a enables the second blade to be located without interference into tight engagement with the threaded opening in the disc. The parts are so arranged and assembled that once the second blade is tightly fastened within its opposed arcuate relief sections and the second to last blade 140 provided with a single arcuate relief Which confronts the first blade when assembled, the last iblade 14b does not require any relieved sections. In order to additionally secure the last blade to the disc, a pin through the shank may be provided if desired.

It will thus be apparent that a simple arrangement providing a threaded connection between a series of blades and a supporting disc for use as an impeller wheel has been provided.

While I have described a preferred embodiment of the invention, it is to be understood the invention is not limited thereto since it may be otherwise embodied Within the scope of the following claims.

I claim:

1. In a turbomachine, a rotor wheel Comprising an annular disc having a plurality of circumferentially spaced radially extending openings arranged about the outer peripheral surface, a plurality of blades disposed within the openings, said blades including a shank portion, a body portion and a platform portion interposed between the body and shank portions, a first group of said blades 4 having one edge section of the platform portion removed, a blade having opposed edge sections of said platform portion removed, and a blade having a substantially circular platform portion free of any relief defining a continuous arcuate edge.

2. In a turbomachine, an annular array of blade members arranged within a casing, at least one member having a threaded shank portion, a body portion and a platform portion, the said platform portion being provided with an arcuate relief positioned to receive and engage a full edge section of an adjacent blade of similar configuration so the blades oiIer mutual resistance to rotation.

References Cited UNITED STATES PATENTS 2,038,670 4/1936 Noack 416-219(UX) FOREIGN PATENTS 378,676 7/1923 Germany 416-207 892,740 3/1962 Great Britain 4l6-219(W) EVERETTE A. POWELL, JR. Primary Examiner US. Cl. X.R. 416-2l2,219

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,565,5 4? ated February 23, 1971 Inventor(s) RAYMOND E. HANSEN It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 21, "field" should read -fluid-- Column 2, line 65, "not" should read -note- Signed and sealed this 28th day of March 1972.

(SEAL) Attest:

EDWARD M.FIE'ICHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Images