Remote Counterweight Pitch Control for Variable-Pitch Rotors
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Solution Overview
Problem
Existing variable-pitch rotor systems face challenges in safely controlling blade pitch angles during actuator failures, with traditional counterweights mounted directly to blades limiting design flexibility and potentially causing overspeeding or excessive structural loads.
Innovation Solution
A pitch control mechanism featuring remotely mounted counterweights that are mechanically interconnected to the blades via a gear system, allowing independent design of counterweights and blades, and utilizing an actuator to adjust pitch angles, ensuring safe operation even in actuator failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If counterweights are mounted directly to the blades, then pitch control safety is improved, but design flexibility is limited
Solution Approach 1:
The system separates the counterweight assembly from the blade structure, with counterweights mounted on a carrier assembly that is independent of the blades. This segmentation allows the counterweights to be designed and positioned independently from the blade design, resolving the contradiction between safety functionality and design flexibility.
Solution Approach 2:
A carrier assembly acts as an intermediary between the counterweights and the rotor hub. The carrier assembly includes a carrier arm that connects the counterweight to the hub, allowing the counterweight to influence blade pitch through mechanical linkage without being directly attached to the blade. This intermediary structure enables both safe pitch control and design flexibility.
2Reliability
If traditional pitch lock mechanisms are used, then actuator failure safety is improved, but device complexity increases
Solution Approach 1:
The system uses a counterweight mounted on a carrier assembly that provides passive safety through centrifugal force during actuator failure. The counterweight automatically drives the blades to a safe pitch angle without requiring complex mechanical locking mechanisms, thus improving safety while reducing complexity.
Solution Approach 2:
The counterweight system is self-regulating through centrifugal force, automatically responding to actuator failure without requiring additional control systems or complex mechanical locks. The system serves itself by using the rotational motion of the rotor to generate the necessary centrifugal force that drives the pitch change.
3Adaptability or versatility
If counterweights are mounted remotely from blades, then design flexibility is improved, but mechanical interconnection complexity increases
Solution Approach 1:
The carrier assembly serves multiple functions: it mounts the counterweight, provides the mechanical linkage to the rotor hub, and transmits the pitch control force. This multi-functionality reduces the need for separate components and simplifies the overall interconnection system despite the remote mounting of counterweights.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables safe control of blade pitch angles during actuator failures while enhancing design flexibility and reducing hub size, thereby improving aerodynamic efficiency and reducing the risk of overspeeding.
Implementation Method 1
at least one moveable counterweight carried by the rotor structure, remote from the blades; and an interconnection between the blades and the counterweight, such that movement of the counterweight causes a change in the pitch angle of the blades
Data Source
AI summary
A pitch control mechanism includes: a rotor structure configured for rotation about a longitudinal axis; a row of blades carried by the rotor structure, each blade having an airfoil and a trunnion mounted for pivoting movement relative to the rotor structure, about a trunnion axis which is perpendicular to the longitudinal axis; a unison ring interconnecting the blades; an actuator connected to the unison ring and the rotor structure, operable to move the unison ring relative to the rotor structure; at least one moveable counterweight carried by the rotor structure, remote from the blades; and an interconnection between the blades and the counterweight, such that movement of the counterweight causes a change in the pitch angle of the blades.