This patent discloses improvements over a mechanism to modulate the pitch of the blades of a fan, turbine or propeller driven by a rotating shaft bearing a helical thread onto which a nut made of a ferromagnetic material was threaded; this nut was spun by electromagnets disposed about it on the stator system and its resultant axial motion manipulated the blades' pitch. This patent discloses refinement of control of the electromagnets employed to spin the axial modulator by embedding a plurality of ferrous protuberances in this nut—the rotational position of which is determined via metallic edge detection sensors whose logic levels are used to selectively energize electromagnets that apply a force onto the protuberances in order to induce rotation and axial motion on the nut. This additional degree of rotational freedom is controlled by this reluctance-motor like configuration while a second motor is used to spin the blades.

This patent discloses improvements over a mechanism to modulate the pitch of the blades of a fan, turbine or propeller driven by a rotating shaft bearing a helical thread onto which a nut made of a ferromagnetic material was threaded; this nut was spun by electromagnets disposed about it on the stator system and its resultant axial motion manipulated the blades' pitch. This patent discloses refinement of control of the electromagnets employed to spin the axial modulator by embedding a plurality of ferrous protuberances in this nut—the rotational position of which is determined via metallic edge detection sensors whose logic levels are used to selectively energize electromagnets that apply a force onto the protuberances in order to induce rotation and axial motion on the nut. This additional degree of rotational freedom is controlled by this reluctance-motor like configuration while a second motor is used to spin the blades.

A rotor head is provided and includes a non-rotating frame, a rotating frame rotatable relative to the non-rotating frame and configured to impart motion to the rotating frame, a rotor hub assembly rotatable about a rotation axis and including a hub and blades extending outwardly from the hub and being pivotable about respective pitch axes thereof and rocker assemblies respectively associated with corresponding ones of the blades. Each rocker assembly is interconnected between the rotating frame and the corresponding one of the blades and configured to convert the motion imparted to the rotating frame into a pitching of one of the blades about the respective pitch axes and amplify the motion such that an angle of the pitching exceeds an angle that would be achieved if the corresponding one of the blades were connected directly to the rotating frame.

A variable pitch fan assembly includes a plurality of rotating trunnion assemblies, a plurality of counterweight assemblies, a first unison ring gear engaged with the trunnion assemblies, and a second unison ring member that restricts out of synch movement of the counterweights relative to each other.

Apparatus are disclosed that are configured to passively rotate a propeller blade from a first pitch angle to a second pitch angle. An example apparatus involves: (a) a rotor hub, (b) at least one dual-pitch support coupled to the rotor hub, wherein the dual-pitch support has a first surface, a second surface and a cavity defined there between, and (c) at least one propeller blade rotatably coupled to the rotor hub such that a blade root is disposed within the dual-pitch support's cavity, where the blade root's front face is positioned against the dual-pitch support's first surface in a first position and the blade root's back face is positioned against the dual-pitch support's second surface in a second position, and the propeller blade is oriented at a first pitch angle in the first position and is oriented at a second pitch angle in the second position.

In response to a torque that is applied to a clutch module not exceeding a torque threshold, the clutch module is locked where a blade is configured to be at a first pitch angle in response to the clutch module being locked. In response to the torque that is applied to the clutch module exceeding the torque threshold, the clutch module is released where the blade has a range of motion which extends from the first pitch angle to a second pitch angle in response to the clutch module being released.

A novel approach to optimizing control accuracy of pitch angle of the blades of an airplane propeller or wind turbine rotor by using laminated rubber (elastomeric) bearings in place of rolling element bearings so that the former's smooth torque vs. deflection characteristics minimally influence the balance of passive control torques upon the pitch axis due to calibrated springs and forces resulting from rotation speed and/or aerodynamic drag.

A propeller includes a blade free to rotate. A first stop is positioned to mechanically engage one or both of a first portion of the blade and a first structure coupled to the blade when the blade is in a first position at a first end of the rotational range of motion. A second stop is positioned to mechanically engage one or both of a second portion of the blade and a second structure coupled to the blade when the blade is in a second position at a second end of the defined rotational range. The blade rotates to the first position against the first stop when the propeller is rotated in a first direction and to the second position against the second stop when the propeller is rotated in a second direction.

A pitch control system configured to vary a pitch angle of at least one of a plurality of propeller blades of a propeller system is provided including a switch movable between a neutral position and a plurality of non-neutral positions. Movement of the switch to a first non-neutral position generates a command to move the propeller blades in a first direction. Movement of the switch to a second non-neutral position generates a command to move the propeller blades in a second direction. Movement of the switch to a third non-neutral position generates a command to move the propeller blades to a zero thrust position.

An exemplary continuous variable pitch rotor system includes a blade extending radially from a hub along a longitudinal axis, the blade rotationally coupled to the hub to permit limited rotation of the blade about the longitudinal axis in response to a change in a rotational speed of the hub. In some embodiments, the blade is held in a radially fixed position relative to the hub. In some embodiments, the blade is permitted to translate radially.