Patent CA-1118686-A (CA)
Inventor: TELFORD JAMES W FALLEN LEAF CO
IPC: F03D3/00
Filed: 1978-08-23
Granted: 1982-02-23
Abstract: PIVOTED BLADE BARREL ROTOR WIND TURBINE                       Abstract of the Disclosure A pivoted blade barrel rotor wind turbine is dis-closed.  The disclosed wind turbine has zero mean camber airfoil blades vertically pivoted at the outer ends of pairs of radius arms.  The inner ends of the radius arms are fixed to a rotating mast.  The rotating mast is journalled in two bearings, one at its upper end and one at its lower end.  The lower bearing is fixed to the ground and the upper bearing is suspended in posi-tion directly above the lower bearing by means of a set of stays.          The outer ends of the stays are fixed to the upper ends of a corresponding set of struts or corner posts.  A second set of stays extends from strut to strut, and each strut is provided with a guy extending under tension from the top of the strut to an anchor affixed to the ground.  Each blade is provided with a steering vane.  Each steering vane is mounted on its associated blade by means of a pair of arms.  The steering vane arms are pivotably fixed to the upper and lower ends of their associated blades.  Each vane can be deflected from one side to the other of its associated blade, past the trailing edge of the associated blade, and thus can cause its associated blade to assume either positive or negative angles of attack with respect to the wind at the turbine.  Each blade can be feathered by locating its assoc-ciated vane in its chord, directly behind its trailing edge. The deflection of each vane with respect to its associated blade is controlled by a cam toggle mechanism.  Each can toggle mechanism is mounted between its associated blade and its associated lower radius arm.  The particularly disclosed cam toggle mechanism in-cludes a double-faced face cam, having a closed cam track on its upper face and another closed cam track on its lower face.  Each 1.     cam track consists of two circular dwell portions, a cuspate active portion, and a smooth or non-singular active portion. The dwell portions of the cam tracks partially overlie each other.      The cusps of the cam tracks lie on opposite sides of the center of the cam. Each cam is fixed to a hollow pivot shaft which in turn is fixed to an associated radius arm, and thus each cam rotates continuously with respect to its associated blade as the wind turbine turns and the blades stream downwind. The cam followers which follow the two tracks of each cam are mounted on a corresponding pair of pivot blocks. Each pair of pivot blocks is pivotably mounted on a member which is fixed to the associated blade. The axes of the cam followers associated with each cam lie on opposite sides of the common pivot axis of the associated pivot blocks. The pivot blocks of each pair are fixed to the opposites ends of a yoke. When the cams rotate continuously with respect to their associated blades, each pair of pivot blocks and their associated yoke are caused to oscillate between two extreme angular positions and to dwell in each extreme angular position for more than 90° of cam rotation each time the associ-ated cam rotates through 360° with respect to its associated blade. A toggle arm is fixed to each upper pivot block and oscillates with it through the same angular positions and dwells.      The outer end of each toggle arm is engaged with a lever con-nected to the vane mounted on its associated blade, and thus each vane can be caused to oscillate between two extreme angular positions on opposite sides of its associated blade and to dwell in those extreme angular positions for more than 90° of cam ro-tation each time its associated cam rotates through 360° with respect to its associated blade. The extreme angular dwell posi-tions of the vanes are substantially equidistant from the chords of their associated blades. Each pivot block is provided with a pair of projecting arms. The inside surfaces of each pair of 2.     projecting arms together define a cam profile.  The cam profiles on the projecting arms of the upper pivot blocks or upper cam profiles, and the cam profiles on the projecting arms of the lower pivot blocks, or lower cam profiles, are all generally U-shaped o C-shaped.  The cam profiles of each pair of pivot blocks are oppositely concave and are symmetrical with respect to a common plane.  That common plane includes the common pivot axis of the pair of pivot blocks.  each face cam is provided with a roller or pin which stands perpendicular to its upper face and is jour-nalled in bearings mounted in a recess in its body.  These upper rollers or pins cooperate with their associated upper cam pro-files to positively couple the respective plate cams to their associated upper pivot blocks during the passage of the upper cam followers through the central parts of the non-singular portions of the upper cam tracks and the passage of the lower cam fol-lowers through the cuspate portions of the lower cam tracks, since otherwise, at these transition times, the coupling between the cam tracks and their associated followers might be indeter-minate.  A similar roller or pin is provided in the lower face of each face cam.  These lower pins cooperate with the lower cam profiles during the passage of the lower cam follower through the central parts of the non-singular portions of the lower cam tracks and the passage of the upper cam followers through the cuspate portions of the upper cam tracks, for the same reason.          A wedge mounted on each lower vane support arm and a pair of vane stops slidably mounted on the bottom of each blade coop-erate to limit the maximum angular deflection of the vanes.  The angular extent of the maximum vane deflection at any time is de-termined by the position of the vane stops with respect to their associated wedges at that time.  At one extreme of travel of the vane stops they contact their associated wedges and thus prevent their associated vanes from being deflected at all, thus feathering their associated blades.  Each of the levers which is operated by one of the toggle arms to couple the motion of that toggle arm to its associated vane support arm is coupled to the associated vane support arm by means of a spring-loaded lost motion mechanism which allows the toggle arm to continue to os-cillate without damaging either its associated cam toggle mecha-nism or its associated vane support arm, etc., even though the vanes are prevented from oscillating by the wedges and vane stops the vane stop assemblies arc moved along guides fixed to the lower edges of the blades by means of control cables working against the restraining action of retracting springs.  Each control cable extends through its associated hollow pivot shaft to its asso-ciated radius arm and thence inwardly along the bottom of the associated radius arm to a pulley fixed to the bottom of the radius arm near the mast.  The inner ends of the control cables, after passing over the pulleys located near the mast, pass down-wardly, parallel to the mast, and are all fixed to a toroidal weight which surrounds the mast.  A massive carriage is mounted on each radius arm to slide outwardly on the radius arm in res-ponse to the centrifugal force resulting from the rotation of the turbine.  Each massive carriage is resiliently restrained from moving outwardly along its associated radius arm by a spring attached to the radius arm and to the carriage.  At a particular speed of rotation of the turbine each carriage will have moved outwardly sufficiently far to engage a stop which is fixed to its associated control cable.  As the speed of rotation of the tur-bine increases above that particular speed the centrifugal forces applied to the control cable stops by their associated carriages overcome the forces applied to the control cables by the toroidal weight and move the stops outwardly along the radius arms, thus tending to slack the control cables.  The parts of the control cables outside the control cable stops are kept taut by their associated retracting springs and thus the vane stops are moved in such a way as to decrease the maximum vane deflection angle.      At a maximum speed of rotation the carriages and thus their asso-ciated control cable stops will have moved sufficiently far out on their associated radius arms so that the vane stops, moved by the control cable retracting springs, contact their associated wedges.  In this condition the blades will be feathered, because the vanes cannot be deflected by the cam toggle mechanisms.  A slidable sleeve surrounds the mast and is of small enough diameter to pass between the toroidal weight and the mast.  This sleeve is provided with a set of ball bearing wheels or rollers on its outer face which are 60 located as to be able to carry the ro-tating toroidal weight when the sleeve is raised far enough up the mast,  The position of the sleeve on the mast is determined by a manual control lever which can be maintained in any one of several selected positions by a detent. The sleeve is prevented from rotating about the mast by the guide means for the linkage which interconnects the manual control lever with the sleeve.          When the sleeve is raised to its highest position by means of the manual control lever the toroidal weight is lifted to far that, independently of the massive carriages, etc., the control cables are slacked enough so that the vane stops are brought into contact with the wedges and thus the blades are feathered, shutting down the turbine under manual control.  The position of the toroidal weight on the mast is also affected by a downward biasing force exerted on the upper end of a sleeve fixed to the upper face of the toroidal weight.  This downward biasing force is provided by a set of levers pivotably mounted in suitable openings in the wall of the hollow mast.  The inner ends of these levers are jointed to a moveable block which can move up and down inside the hollow mast.  A cable fixed to the moveable block ex-tends upwardly through the interior of the hollow mast, through 5.     an extension of the mast, and through a bearing located in the upper end of the mast extension. The outer end of this cable is affixed to a parachute-like drogue, which acts to sense the force of the wind passing over the turbine. The pull on the cable exerted by the wind force acting on the drogue biases the torodial weight downwardly and thus tends to move the vane stops in such a way as to increase the maximum deflection of the vanes. When the strength of the wind at the turbine decreases, the downward bias force applied to the torodial weight is decreased, allowing the torodial weight to rise in response to the urging of the control cable retracting springs acting through the control cable. Thus the vane stops move closer to their associated wedges at low wind strengths, and the maximum angle of attack of the turbine blades is reduced. An alternative cam toggle mechanism is disclosed in which the cams are plate cams, rather than face cams.