Interleaved Tooth Reference Tubes for Torque and Azimuth Sensing
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Solution Overview
Problem
Existing torque measurement systems for rotor masts in aircraft are susceptible to temperature variations and require multiple sensors, increasing complexity and accuracy issues.
Innovation Solution
A system using three redundant variable reluctance sensors positioned around an interleaved array of teeth on two reference tubes, where one tube is associated with the rotor mast and the other with an input gear, allowing for simultaneous measurement of torque, RPM, and azimuth, with a missing tooth on the rotor mast tube enabling azimuth determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple sensors are used to measure torque, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple measurement functions (torque, RPM, azimuth) into a single sensor system. The variable reluctance sensor simultaneously detects torque through the rotor mast reference tube and measures rotational speed and angular position through the gear reference tube, eliminating the need for multiple separate sensors and reducing system complexity while maintaining measurement reliability
Solution Approach 2:
The reference tube system serves multiple functions: it acts as both a torque measurement element (through the rotor mast reference tube experiencing torsional force) and a rotational position/speed measurement element (through the gear reference tube with teeth). This multi-functionality allows a single sensor system to perform what would traditionally require multiple specialized sensors
2Reliability
If multiple sensors are deployed, then measurement coverage is improved, but susceptibility to temperature variations increases
Solution Approach 1:
By merging torque and rotational measurements into a single sensor system, the patent reduces the number of electronic components exposed to temperature variations. The single variable reluctance sensor is housed in a protected manifold, minimizing thermal exposure while maintaining comprehensive measurement coverage through the combined reference tube system
3Device complexity
If a single sensor system is used, then device complexity is reduced, but measurement precision may be compromised
Solution Approach 1:
The patent segments the measurement function into two separate reference tubes: the rotor mast reference tube for torque measurement and the gear reference tube for rotational position and speed measurement. This segmentation allows each tube to be optimized for its specific function while being measured by a single sensor, maintaining precision without requiring multiple sensor systems
Solution Approach 2:
The reference tubes act as intermediary elements that translate physical quantities (torque, rotational position) into geometric variations (distance between teeth) that the variable reluctance sensor can detect. This intermediary mechanism ensures high measurement precision while keeping the sensor system simple and unified
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
Enables accurate measurement of torque, RPM, and azimuth at a single point, reducing complexity and susceptibility to temperature variations, while detecting torsional anomalies and mast misalignment.
Implementation Method 1
a sensor system comprising a first variable resistance sensor ('VRS') configured to detect a presence of successive teeth of the interleaved set of teeth and generate an output signal indicative thereof
Data Source
AI summary
One embodiment is an apparatus including an inner reference tube associated with a load-bearing rotating shaft and having a first set of teeth associated therewith and disposed around a periphery thereof; an outer reference tube associated with an input gear and disposed about the inner reference, the outer reference tube and having a second set of teeth associated therewith and disposed around a periphery thereof wherein teeth comprising the second set of teeth are interleaved with teeth comprising the first set of teeth to comprise an interleaved set of teeth and wherein the inner reference tube and the outer reference tube rotate about a same longitudinal axis and at a same speed as the rotating shaft; and a sensor system comprising a first variable resistance sensor (“VRS”) configured to detect a presence of successive teeth of the interleaved set of teeth and generate an output signal indicative thereof.