US2726844A - Automatic variable angle turbo-jet rotor blades - Google Patents

Description

3, 1955 .1. E. WALTON 2,726,844

AUTOMATIC VARIABLE ANGLE TURBO-JET ROTOR BLADES Filed Sept. 25, 1952 gimme/whom JOHN E. WALTON .United States Patent AUTOMATIC VARIABLE ANGLE TURBO-JET ROTOR BLADES John Edward Walton, Drexel Hill, Pa., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application September 25, 1952, Serial No. 311,385

2 Claims. (Cl. 253- 59) This invention relates generally to blade angle adjustment assemblies for rotating bladed bodies, and particularly to improved means for adjusting the blade angle setting of turbo jet rotor blades in response to an engine variable, as rotor speed, to obtain better turbine and compressor operating efiiciency throughout the entire speed range of these engines.

The angle at which turbine and compressor blades are set, is a compromise to realize the best average efiiciency over the entire engine speed range, wherefore operation at a speed at variance with the average speed results in a considerable loss of efliciency. Accordingly an object of the invention is to provide means responsive to an engine characteristic that varies with engine operation, such as rotor speed, compressor pressure rise, and turbine outlet temperature, for constantly resetting the blade angle setting to maintain a higher blade efliciency.

Another object of the invention is to provide rotor blade angle adjusting means that derives its operating force and breaks the force down into two components, one directed to rotate the blades and the other directed to oppose the centrifugal force of the rotating blades so as to alleviate any frictional resistance to blade rotation caused by the blade centrifugal force.

Other objects and features of importance will become apparent in following the description of the drawing, wherein Fig. l is a fragmentary perspective view of a rotor with its setting adjustment means.

Fig. 2 is a fragmentary sectional view of the rotor, the blade angle adjusting means shown in elevation, and

Fig. 3 is a sectional view taken on the line 33 of Fig. 2 and in the direction of the arrows.

The rotor fragment is schematically illustrated and represents either a compressor or turbine component. It is provided with a radial bore 12 extending inwardly from the rotary periphery and a recess 14 in communication with the lower end thereof. A blade 16 forming a part of the rotor, has its shank 18 disposed in the bore 12 and is mounted for rotation about its longitudinal axis in the rotor. A blade retainer such as ring 20, is fixed to the blade shank 18 intermediate the ends of the shank, and is mounted for rotation in the cylindrical opening 22, the latter being larger in diameter than bore 12 and located between the inner and outer ends of the bore. The upper wall 24 of opening 22 serves as an abutment or seat for the retainer 20, preventing the blade and shank from sliding radially from the rotor, but permitting rotary movement of the blade.

Means responsive to an engine variable, are provided for constantly shifting the blade setting for the reasons mentioned hereinbefore. The illustrated means consists of a flyweight 26 including a weight 28 mounted at the outer end of a lever arm 30, the latter being a part of a lever of the first class. Hence, there is a pivot pin 32 constituting a fulcrum for the lever between the ends of arm 30, and this pin is secured to the rotor in recess 14.

2,726,844 Patented Dec. 13, 1955 The inner end of lever arm 30 has bifurcations 34 to which driver pins or trunnions 36; are secured. It is noted that only one trunnion may be used, if desired, or a single pin may be substituted. When a pair of trunnions are used-generally helical grooves or slots 38 are formed in the lower end of shank 18 accommodating the driver trunnions, so that the shank 18 is rotated in the rotor in response to lever actuation through the action of the driver trunnions 36 sliding in the slots 38.

In operation the rotor is actuated in the usual way. Instead of the blade setting being fixed in a compromise position for average speed, it is constantly adjusted to the most efiicient setting for each speed. This is accomplished by centrifugal force applied to one end of the lever arm 30 and acting at the counterweight 28 tending to move the lever about its pivot 32. Any lever motion is converted to rotary movement of the blade shank 18 by the driver pins 36 sliding in the grooves 38. However, the application of force F to the blade shank is in two directions in as much as this force is applied as two components T and N at the center of pins 36. The component T exerts a torsional load on the blade shank 18 while the component N is applied generally in the direction opposite to the centrifugal force of rotating blade 16. This component N alleviates the frictional resistance to rotation which is present at the point of contact between retainer 20 and its seat 24. To show the action of force N, the space between the retainer and seat 24 is present in Fig. 2, although in practice it would not appear.

It is apparent that various modifications may be made without departing from the scope of the following claims.

What is claimed is:

1. In an elastic fluid engine, a rotor having a bore extending radially inwardly from the periphery thereof and a recess extending laterally through a side surface thereof and communicating with the inner end of said bore, a rotor blade having a shank, said shank being rotatably disposed in said bore, an opening in said bore of larger diameter than said bore and retaining means fixed to said shank mounted for rotation in said opening, said retaining means bearing against a wall of said opening to thereby retain said blade in said rotor under the action of centrifugal force, a lever having a weight at one end thereof pivotally mounted between its ends on a pivot pin, said pivot pin being secured to said rotor and lying transversely of the direction of centrifugal force, a part of said shank traversing said recess and having a groove therein and curving thereabout, the other end of said lever having means thereon accommodated in said groove, whereby as centrifugal force acts on said weight, said latter mentioned means will exert a force on said shank, one component of which will tend to rotate said shank and blade and one component of which will tend to alleviate the frictional resistance to rotation present at the point of contact between said retaining means and said wall of said opening.

2. In a turbine rotor, a bore in said rotor extending radially inwardly from the periphery thereof, a recess extending laterally through one side surface of said rotor and communicating with the inner end of said bore, a rotor blade, a shank extending from said blade and disposed in said bore, the inner end of said shank extending into said recess and having a groove therein and curving thereabout, a lever having a weight at one end and pivotally supported intermediate its ends by a pivot pin, said pivot pin being secured to said rotor in said recess and being disposed to permit said weight to move said lever under the action of centrifugal force as said rotor rotates, a driver pin carried by said lever at the end thereof opposite to said weight, said pin being accommodated in the groove of said shank, wher eby said lever will be pivoted about said pivot pin under the action of centrifugal force, and said lever motion will be converted to rotary movement of the blade shank in said bore, said rotor having a wall adjacent said bore and extending generally transversely thereofi and meanson said shank inwardly of said wall and engaging said wall at least during certain periods of rotation of'said rotor to retain said shank in said bore.

References Cited in the file of this patent UNITED STATES PATENTS 1,482,690 Lanzius Feb. 5, 1924 1,903,628 Landrum Apr. 11, 1933 FOREIGN PATENTS 705,835 France Mar. 17, 193 945,342 France Nov. 29, 1948

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