Blade Angle Feedback System with Profiled Marker Terminations
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Solution Overview
Problem
Existing blade angle feedback systems for aircraft propeller systems are vulnerable to 'edge-effects' that increase reading errors as sensors approach the edges of the feedback device, leading to inaccurate measurements of propeller blade pitch.
Innovation Solution
The geometry of the position markers on the feedback device is modified to be symmetrical about the geometric centerline, with beveled or arcuate terminations to maintain magnetic symmetry and reduce edge-related effects, allowing accurate detection by sensors even near the edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional position markers with straight terminations are used on the feedback device, then the device complexity is low and manufacturing is simple, but reading errors increase as the sensor approaches the edges of the feedback device due to edge-effects
Solution Approach 1:
The position markers are designed with different geometries based on their location on the feedback device. Markers near the edges have beveled or arcuate terminations to compensate for edge-effects, while central markers maintain straight terminations. This local differentiation optimizes measurement accuracy at each position without unnecessarily complicating the entire device.
Solution Approach 2:
The geometry parameters of the position markers are modified to address edge-effects. Specifically, the termination shapes are changed from straight to beveled or arcuate forms, and the radial distances of edge markers are adjusted. These parameter changes compensate for the magnetic field distortions that occur near the edges of the feedback device.
2Adaptability or versatility
If the sensor is positioned to read markers across the entire feedback device including edges, then complete blade angle coverage is achieved, but reading errors increase at edge positions
Solution Approach 1:
Different position markers are designed with different termination geometries according to their specific location on the feedback device. Edge markers feature beveled or arcuate terminations to mitigate edge-effects, while central markers use straight terminations. This localized optimization allows the sensor to accurately read markers across the entire feedback device perimeter.
Solution Approach 2:
The position markers are pre-configured with appropriate termination geometries during manufacturing to anticipate and compensate for edge-effects before the sensor encounters them. This preliminary geometric adjustment ensures that even when the sensor reads edge markers, the measurement accuracy is maintained.
3Area of stationary object
If position markers are placed at the edges of the feedback device to maximize measurement coverage, then the measurement range is improved, but edge-effects cause increased reading errors
Solution Approach 1:
Position markers at different locations on the feedback device are designed with location-specific termination geometries. Edge markers have beveled or arcuate terminations to compensate for edge-effects, while central markers have straight terminations. This allows full utilization of the feedback device area while maintaining measurement accuracy at all positions.
Solution Approach 2:
The markers are pre-positioned and pre-shaped during fabrication to account for edge-effects before operation. The beveled or arcuate terminations are built into the marker geometry at designated edge positions, enabling accurate readings across the maximum possible area of the feedback device.
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 modification reduces reading errors and improves the accuracy of blade pitch measurements, ensuring precise control of propeller blade angles in various operational modes.
Implementation Method 1
a sensor can be used to measure the rotation of the feedback device via the markers, providing a proxy value for the rotational velocity of the engine
Data Source
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AI summary
A blade angle feedback assembly (200) for an aircraft-bladed rotor (130) rotatable about a longitudinal axis (A) and having an adjustable blade pitch angle comprises a feedback device (204) coupled to rotate with the rotor (130), the feedback device (204) having a root surface (304) having a first edge (3021), first position markers (402) extending from the root surface (304) and oriented substantially parallel to the axis (A), the first position markers (402) circumferentially spaced from one another, at least one second position marker (404) extending from the root surface (304) and positioned between two adjacent first position markers (402) at an angle thereto, the at least one second position marker (404) having an end (406) positioned adjacent to the first edge (3021) and non-flush therewith, and at least one sensor (212) mounted adjacent the feedback device (204) and configured to detect a passage of the first position markers (402) and the at least one second position marker (404) as the feedback device (204) rotates about the axis (A).