US 2460849 A
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v Feb. 8, 1949. J. A. SENN CONSTANT SPEED ROTOR FOR TURBINES Filed July 16, 1945 Patented Feb. 8, 1949 CONSTANT SPEED ROTOR FOR TURBINES Jurg A. Senn, Milwaukee, Wis., assignor to the United States of America as represented by the Secretary of War Application July 16, 1945, Serial No. 605,449
3 Claims.- (Cl. 170-159) (Granted under the act of March 3, 1883, as
amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment of any royalty thereon.
This invention relates to rotors, and more particularly to improvements in rotors especially adapted for use in turbines to provide automatic speed regulation.
In turbines operated by steam, air, water, or other fluids, it is often difficult to maintain a uniform speed, with the result, for example, that the voltage output of an electric generator connected to the turbine varies widely with variable fluid flow, or with variable load. This is objectionable where a constant value of voltage is desired, as the voltage of the generator varies with the speed of the turbine rotor.
It is, therefore, an object of this invention to provide in a turbine a rotor having flexible blades to compensate for variations of the fluid flow or load so that the speed regulation will be good without requiring bulky or complicated equipment for controlling speed.
A further object is the provision of a rotor for a turbine which is so constructed as to effectively react to and direct the flow of air or other fluids against the blades.
These and other objects are attained by the novel construction hereinafter described and illustrated by the accompanying drawings, forming a part hereof, and in which:
Fig. 1 is a perspective view of the base piece of a rotor embodying the invention.
Fig. 2 is a plan or frontview of the complete rotor, the arrows a indicating air deflection currents, and the arrow b indicating the direction of rotation of the rotor.
Fig. 3 is an elevational view of the rotor, the arrow a indicating the relative direction of incident fluid.
Referring to the drawings, the rotor body is shown to comprise a square flat plate base 6 from which rectangular legs 3 project upwardly at respective edges of the plate 6. These legs are in the form of thin planiform walls of uniform height flush with respective edges of the plate and each extending from an intermediate point at its side of the plate in a counter clockwise direction to the next corner of the plate, somewhat less than one-half the length of the side of the plate 6. The height of these legs is nearly one-half the height of the rotor body piece. The upper edges of the legs 3 are provided with projections 4, under which are clipped extremities 2 of flexible elastic curved turbine blades 2, the latter being also snugly fitted about the legs 3. It will be seen that this structure enables the blades to be readily and conveniently clipped about the legs without necessitating the use of tools.
It may be seen that the blades are of thin band metal of uniform thickness throughout, and rectilinear in their transverse dimension, this dimension being coincident with the direction of relative flow of ambient fluid in operation of the device.
An air distributor extends upwardly from the base 6, and comprises four vanes 5 having leading edges forming a cross at the top and center of the rotor. The arms of the cross in this instance are normal to the vertical planes of the sides of the plate 6, and stop short of such planes a distance. The rotor is intended to rotate in a clockwise direction as viewed in Fig. 2, and from the advancing edges of the cross-shaped top of the body respective vertical planiform faces of the vanes 5 extend to the plate 6. From the rear side of the arm of the cross at the top of each vane 5, a curved incident surface or airfoil l slopes down to a trailing edge at the base. An air stream striking the surfaces axially is divided and directed outwardly against the blades 2. In the present instance the surfaces 1 are each in the form of the geometrical projection of a segment of a cylinder having its axis parallel to the respective arm of the cross and very near the plane of the cross, so that a plane perpendicular to the plate 6 at said free edge of this arm is approximately or nearly tangent to such projected cylinder. degrees, more or less, around the said axis in the instance illustrated. The shape of the curve of the surface I and its extent, may, however, be designed in accordance with turbine practices. It is to be noted that the surface 1 is of such form and extent that the reaction forces applied to the turbine at the surfaces 1 will be substantially less than the total potential. practicably convertible energy of inertia of the fluid encountered by the rotor when advanced along its axis. The surfaces I will deflect the incident fluid, resulting in imparting a radial component of motion to the current with respect to the axis of the rotor, and impingment of the current upon the inner faces of the blades 2. At slow speeds this impingement of the current will produce a minimum defiection of the blades, and will be at a maximum angle of incidence, so that efllciency of the blades The surface at I subtends an angle of 72 smaller increment of power from the blades.
It will be evident from the shape and sizes of the parts of the rotor body as described, that it is a rigid structure with no quality of variation of contours in use such as would materially afiect its reaction efliciency. The inclination of the foil surface I or its chord may be termed the pitch of the foil surface for the purpose of this application, and it is apparent that it has components of inclinationradially at its lower part. The base may be fastened to a suitable shaft (not shown).
The blades vary in curvature with speed, thus changing the effective projected area and, therefore, providing substantially constant speed.
The reaction of the fluid leaving the curved distributor surfaces 7 also adds to the torque, especially since these surfaces are off-center. the blades straighten into radial positions their back surfaces interfere with the free discha ge of the congested air in the turbine so that a braking action is applied to the rotor for high speeds.
The above description is to be considered as illustrative and not limitative of the invention, of
which modifications can be made without departing from the spirit and scope: as denoted in the appended claims.
The invention having been described, what is claimed is:
1. A rotor for a turbine comprising a rectangular base, rectangular legs projecting from the base, flexible blades having one end wound about the legs, projections of the legs to hold the blades in place, four vanes projecting from and forming a cross at the center of the base, and curved surfaces sloping from the free edges of the vanes to the base.
said legs and projecting laterally therefrom, intersecting vanes projecting from the base, and curved surfaces extending from the free edges of the vanes to the base.
3. In a constant speed rotor for turbines, a rigid rotor body having lateral rigid vane elements thereon each formed with a leading edge and a trailing edge and an inclined incident surface therebetween-having a pitch with a substantial component of radial inclination, said incident surface being of such extent and form as to derive a fraction of the sum of torque forces which the rotor is designed to produce when the rotor is relativelyadvanced axially in a fluid, and respective thin elastic radially flexible curved blades for each said air foil element, each blade having one end flxed to said body, said blades having a uniform thickness and being substantially rectilinear transversely, their transverse dimensions being coincident with the direction of the said axis of the rotor whereby to offer a minimum reaction to a fluid current moving axially in relation to the rotor, said blades being inclined across the paths of fluid deflected 'by the respective rigid foil elements and being yieldable to at least said deflected fluid exceeding predetermined velocity in the direction of incidence of such deflected fluid on the blades so as to derive supplemental torque forces in the rotor inversely proportional to increase of said relative speed of the fluid above said predetermined value.
JURG A. SENN.
Bar-masons orren The following references are of record in the flle of this patent:
UNITED STATES PATENTS 40 Number Name Date 346,471 Falcon Aug. 3, 1886 632,740 Parker Sept. 12, 1899 1,142,915 Scott June 15, 1915 1,416,384 Schmelzer May 16,- 1922 1,473,066 Wells Nov. 6, 1923 1,869,802 Dore Aug. 2, 1932 2,144,860 Thorp Jan. 24, 1939