GB767907A - Improved variable pitch air-driven bladed rotor unit - Google Patents

Abstract

767,907. Wind-motors. GENERAL MOTORS CORPORATION. March 23, 1955 [April 1, 1954; April 1, 1954], No. 8393/55. Class 110 (3). A wind motor comprising flyweights, responsive to centrifugal force due to the rotation of the rotor, rotatable about the longitudinal axis of each blade so as to move upon rotation of the rotor in a direction similar to that of the blade toward a high pitch position has resilient means interconnecting each blade and associated flyweight which biases the blade toward the high pitch position and resilient means connected with the flyweights to oppose their movement under the action of centrifugal force. The rotor of a wind motor comprises a hub 20 in which are pivotably mounted the aerofoil section blades 31 by ball bearings 30. A retainer 50 is attached to the root of each blade by a nut 40 and relative movement between the blade and retainer is prevented by tangs 57. One end of a torsion spring 55 located in a groove 51 of the retainer is passed through wall 58 and the other end is attached to a flyweight 65, Fig. 4. Each flyweight is mounted by a ball bearing 62 in the retainer 50 and carries a pair of pins 66, 67. The pins 66 abut against the output shaft 25 and the pins 67 project into the cut-away portion of the wall 52, Fig. 6, of the retainer 50. The pins 67 are also engaged by a pair of links 70 which are pivotally connected to a collar 73 slidable on the shaft 25. The collar 73 is urged to the left by a spring 74. When the rotor is stationary, the pins 67 engage the shoulder 53, Fig. 6, and the pins 66 engage the shaft 25 and the blades are set to a high pitch stop position of approximately 75 degrees. When the rotor starts to rotate, the forces on the blades rotate the retainers 50 until the shoulders 54, Fig. 4, engage the pins 67. In this position the opposed forces of the governor spring 74 and the centrifugal twisting moments on the blades are in equilibrium with the centrifugal force on the flyweights and the aerodynamic twisting moment on the blades. The flyweights then govern the speed of the rotor. A pin 80 coacts with surfaces 82, 83 to limit the movement of the blade. In a modification the torsion spring 55 is replaced by a coiled tension spring and the flyweights in the form of a major segment of a cylinder having an arm which engages the shaft 25. This arm enables the pin 66 to be dispensed with. The governor spring 74 may be replaced by a pair of coaxial springs.