Variable Pitch Rotor Control Mechanism Reducing Parasitic Forces
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Solution Overview
Problem
Existing rotor systems with variable collective pitch blades require significant control forces to vary the pitch of blades due to parasitic forces generated by the current mechanical arrangements, leading to increased friction and maintenance needs.
Innovation Solution
A rotor system with a control plate that uses an angular positioning tube connected to the hub via a combined link, minimizing parasitic forces by maintaining pitch rods in a privileged position, and employing a rolling mechanism to reduce friction and wear, allowing for reduced control forces and optimized mass distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If splines are used to connect the control plate and hub in rotation, then the control plate can be mechanically connected to the hub, but significant friction forces are generated between the splines requiring relatively large control forces
Solution Approach 1:
The patent replaces the traditional spline mechanical connection with a compass mechanism that uses ball joints to connect the control plate to the hub. This substitution eliminates the sliding friction inherent in spline connections by using spherical roller contacts, thereby reducing the control forces required to operate the pitch control system while maintaining mechanical connection strength.
2Ease of operation
If ball joints are used to connect pitch rods to the control plate, then the pitch rods can be articulated to the control plate, but the translation of the control plate induces an inclination of the pitch rods creating tangential parasitic forces
Solution Approach 1:
The patent positions the ball joints of the pitch rods at the same radial distance from the rotor axis as the control plate's rotation center. This geometric arrangement ensures that when the control plate rotates, the pitch rods remain parallel to the rotor axis throughout the motion, eliminating the inclination-induced parasitic forces while maintaining smooth articulation.
3Force
If a compass is used to connect the control plate and hub in rotation, then torque can be transmitted without notable increase in control force, but the joints tend to wear out inducing regular maintenance operations
Solution Approach 1:
The patent designs the compass mechanism with self-lubricating properties and load-distributing ball joint geometry that automatically compensates for wear. The spherical contacts and proper clearance design allow the mechanism to maintain low friction operation over time, reducing the frequency of maintenance operations while keeping control forces low.
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 design reduces the control forces required to vary the pitch of blades, minimizes parasitic forces, and decreases maintenance needs by reducing friction and wear, while maintaining efficient operation of the rotor system.
Implementation Method 1
the control plate (40) being carried by the first end (32) by a rolling mechanism (50)
Data Source
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
The present invention relates to a variable collective pitch rotor (1) that rotates about an axis of rotation (AXROT). This variable collective pitch rotor comprises a plurality of blades (15). A control mechanism includes a control rod (31) mounted to move in translation relative to the hub (10) and a control plate (40) mounted to rotate on the control rod (31). Pitch rods (60) are articulated to the control plate (40) and to pitch levers (18) of the blades (15). The control mechanism includes an angular positioning tube (80) that is rotationally and translationally fixed to the control plate (40). The hub (10) and the angular positioning tube (80) are connected by a combined linkage (83) which induces rotation about the axis of rotation (AXROT) of said angular positioning tube (80) and said control plate (40) relative to the hub (10) during a translation of the angular positioning tube (80).