Phonic Wheel Tooth Design for Accurate Pitch Feedback
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Solution Overview
Problem
Providing accurate and reliable feedback on the angular position of variable pitch propeller blades in aircraft is challenging due to limited space on aircraft engines, which can lead to hazardous conditions if blades transition into excessively low or reverse beta angles.
Innovation Solution
A phonic wheel system with a tooth configuration that includes a raised axial end and a mid portion of substantially uniform height, used in conjunction with a sensor to generate a feedback signal indicative of the pitch position of pitch-adjustable blades, mitigating edge effects and allowing for accurate detection of the tooth's position within a magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional phonic wheel with uniform tooth height is used, then the structure is simple, but the sensor detection accuracy is reduced due to edge effects in the magnetic field
Solution Approach 1:
The tooth structure is designed with different heights at different locations: the first axial end has a greater height than the mid portion, creating local variation in the magnetic field interaction. This local quality change allows the sensor to detect the tooth more accurately by reducing edge effects at the detection point while maintaining a relatively simple overall structure.
2Measurement precision
If the phonic wheel is placed in limited engine space, then the system fits within available space, but the sensor cannot accurately detect tooth position due to spatial constraints affecting magnetic field distribution
Solution Approach 1:
By creating a localized height variation at the first axial end of the tooth, the invention optimizes the magnetic field interaction specifically at the sensor detection point. This allows accurate detection within constrained engine space without requiring additional axial length or modifying the overall compact structure of the phonic wheel.
Solution Approach 2:
The invention addresses the two-dimensional constraint of engine space by introducing a dimensional variation in the tooth height along the axial direction. This creates a third dimension (height variation) that improves detection accuracy without increasing the radial or circumferential footprint of the phonic wheel, allowing it to fit within limited engine space.
3Measurement precision
If the tooth height is increased to improve sensor detection, then detection accuracy improves, but the device occupies more axial space which is not available in constrained engine environments
Solution Approach 1:
Instead of uniformly increasing the tooth height along its entire length, the invention applies height increase only at the first axial end where the sensor detects the tooth. The mid portion maintains a substantially uniform, compact height. This localized approach improves sensor signal accuracy while minimizing the axial length occupied by the tooth, making it suitable for constrained engine environments.
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 effectively provides accurate feedback on the angular position of propeller blades, reducing the risk of hazardous conditions by ensuring precise control of blade pitch, even in constrained engine spaces.
Implementation Method 1
directing a magnetic field from a sensor toward a location that a tooth of the phonic wheel is expected to occupy as the tooth rotates relative to the sensor, the magnetic field including magnetic flux intersecting the location that the rotating tooth is expected to occupy
Implementation Method 2
detecting a variation in the magnetic field caused by movement of the tooth in the magnetic field
Data Source
AI summary
A phonic wheel having a body and a tooth is disclosed. An embodiment of the phonic wheel includes a body that is configured to rotate about a rotation axis. The tooth is attached to the body. The tooth has a first axial end relative to the rotation axis, a second axial end opposite the first axial end, and a mid portion extending between the first and second axial ends. The mid portion has a substantially axially uniform height from the body. The first axial end has a greater height from the body than the height of the mid portion.