Hybrid Speed Sensing System for Aircraft Engines
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Solution Overview
Problem
Existing engine speed sensing systems are complex, expensive, and increase the weight and size of engines due to the need for additional features like dedicated readable markers, which complicates axial space and length.
Innovation Solution
A feedback system for aircraft engines featuring a hybrid feedback device with non-ferromagnetic and ferromagnetic materials, including position markers and a sealing member, which are designed to fit into cavities and securely couple to the engine shaft, using Mu-metal for enhanced signal strength and a thermoplastic body for reduced weight and improved signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated readable markers are added for speed sensing, then speed measurement capability is improved, but weight and size of the engine increase
Solution Approach 1:
The feedback device combines multiple functions into a single integrated component: speed sensing through position markers, sealing function through the sealing member, and structural support through the body with cavities. This merging eliminates the need for separate dedicated speed sensing markers, reducing overall weight and size while maintaining speed measurement capability.
Solution Approach 2:
The feedback device serves multiple purposes simultaneously: it provides speed sensing information through position markers, acts as a seal between the rotating and stationary portions, and provides structural mounting features. This multi-functionality reduces the need for additional separate components that would increase weight and size.
2Measurement precision
If dedicated readable markers are added for speed sensing, then speed measurement capability is improved, but axial space and overall engine length increase
Solution Approach 1:
The position markers are arranged circumferentially around the feedback device rather than extending axially. This circumferential arrangement allows speed sensing information to be obtained in the radial dimension, eliminating the need for additional axial space that would be required for linear marker arrangements.
Solution Approach 2:
The position markers are embedded within cavities in the feedback device body, creating a nested structure. This nesting allows the markers to be contained within the existing axial envelope of the feedback device without extending the overall engine length.
3Measurement precision
If existing speed measurement systems are used, then speed sensing is achieved, but system complexity and cost increase
Solution Approach 1:
The feedback device merges speed sensing functionality with the existing sealing and structural requirements of the engine. By integrating position markers into the feedback device that already serves sealing and mounting functions, the system avoids adding separate dedicated speed sensing components, thereby reducing overall system complexity.
Solution Approach 2:
The feedback device provides its own speed sensing capability through integrated position markers without requiring external dedicated speed sensing systems. The device serves itself by incorporating the necessary sensing features into its own structure, eliminating the need for additional complex external systems.
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 measures rotational speed with reduced weight and size, improved signal strength, and enhanced accuracy by using Mu-metal position markers and a thermoplastic body, addressing the complexity and cost issues of existing systems.
Implementation Method 1
the non-ferromagnetic material has a first magnetic permeability and the ferromagnetic material has a second magnetic permeability greater than the first magnetic permeability
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A feedback device (204; 204') or phonic wheel is coupled to rotate with a rotating component of an aircraft engine (10). The feedback device (204; 204') comprises a body (302; 302'; 606) having cavities (406) defined therein and circumferentially spaced thereabout, each cavity (406) configured to receive therein a position marker (306; 306'), the body (302; 302'; 606) made of a non-ferromagnetic material and the position markers (306; 306') comprising a ferromagnetic material. A sealing member (304; 304') is configured to be secured to the body (302; 302'; 606) for retaining the position markers (306; 306') within the cavities (406). At least one sensor (212) is positioned adjacent the feedback device (204; 204') and configured for producing, as the feedback device (204; 204') rotates about a longitudinal axis (A) with the rotating component, at least one sensor signal in response to detecting passage of the position markers (306; 306'). A processing unit (220) is communicatively coupled to the at least one sensor (212) and configured to determine a rotational speed of the rotating component from the at least one sensor signal received from the at least one sensor (212).