Helical Blade Pitch Control via Centrifugal and Elastic Forces
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Solution Overview
Problem
Existing pitch control systems for turbomachines are complex, expensive, and prone to failures due to sensor inaccuracies, power outages, and user errors, limiting their applicability and reliability, especially in smaller turbomachines like RC aircraft propellers.
Innovation Solution
A simplified pitch control system featuring a hub with blade housings that allow blades to spiral along a helical path, utilizing elastic members and a guide mechanism with constrained-motion relationships to adjust pitch based on centrifugal and elastic forces, eliminating the need for complex electronics and sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If advanced pitch control systems with separate motors and sensors are used for each blade, then pitch control precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent merges the pitch control function from individual blade motors into a single hub-mounted mechanism. The hub mechanism controls the pitch of all blades simultaneously through a centralized system, eliminating the need for separate motors and sensors on each blade while maintaining control precision.
Solution Approach 2:
The hub-mounted pitch control mechanism serves as a universal control system that manages pitch for all blades in the array. This single mechanism performs the function that previously required multiple independent systems, reducing overall device complexity while maintaining control capabilities.
2Measurement precision
If multiple sensors and electronic components are installed on each blade, then pitch control accuracy is improved, but system reliability decreases due to more potential failure points
Solution Approach 1:
The patent extracts the electronic sensors and control components from the blade structure and relocates them to the hub. This removal eliminates potential failure points on the blades while concentrating the electronic systems in a more protected and accessible location for maintenance.
Solution Approach 2:
The system incorporates mechanical feedback mechanisms that allow the pitch control system to self-regulate based on blade position and aerodynamic forces, reducing dependence on electronic sensors and computational control, thereby improving reliability.
3Extent of automation
If complex linkages and swashplates are used for blade pitching, then continuous pitch variation is achieved, but device complexity and applicability range are limited
Solution Approach 1:
The patent replaces complex mechanical linkages and swashplates with a simpler hub-mounted mechanism that uses elastic members and centrifugal force principles to achieve continuous pitch variation. This substitution maintains the automated pitch control function while dramatically reducing mechanical complexity.
Solution Approach 2:
The system achieves continuous pitch variation by changing operational parameters such as rotational speed and elastic member tension rather than through complex mechanical linkages. This allows for smooth, continuous adjustment of blade pitch across a wide range of operating conditions.
4Extent of automation
If pitch control systems with multiple electronic components are deployed, then automated pitch adjustment is achieved, but susceptibility to power outages and electrical failures increases
Solution Approach 1:
The pitch control system incorporates passive mechanical elements such as elastic members and centrifugal force mechanisms that automatically adjust blade pitch based on physical parameters without requiring electrical power. This self-regulating capability maintains automated pitch adjustment functionality while eliminating vulnerability to power outages and electrical failures.
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
The system provides broad applicability, simplicity, low cost, low maintenance, durability, and reliability, unaffected by power losses, electronics failures, sensor inaccuracies, or user errors, enhancing the performance and endurance of turbomachines.
Implementation Method 1
One or more elastic members (3) directly or indirectly draw the blade (2) toward the hub axis (40)... The blade (1) is subjected to the elastic force and a centrifugal force.
Implementation Method 2
The centrifugal force arises as a result of hub (12) rotation, which causes blades (1) to rotate about the hub axis (40)... When the component of centrifugal force is greater than the component of elastic force the blade (1) is drawn away from the hub axis (40)
Data Source
AI summary
A pitch control system characterized by a hub with at least two blade housings on the hub that are disposed around the hub axis. The blade housings have corresponding blades that engage with them. The blades spiral along housing longitudinal axes toward and away from the hub axis about a segment of helical path to effect a change in the pitch of each blade. One or more elastic members draw the blades toward the hub axis, either directly or indirectly. There are pitch mechanisms effective to facilitate blades to spiral around housing-longitudinal axes. A blade will spiral away from the hub axis when the centrifugal force exerted on the blade exceeds the opposing elastic force in the housing-longitudinal direction (neglecting other forces). Conversely, blades spiral toward the hub axis when said centrifugal force is less than said elastic force. There is an imaginary plane orthogonal to the hub axis. Housing-longitudinal axes have angles with respect to the imaginary plane of not more than 30 degrees.