Proximity Shaft Angle Measurement Using Variable-Radius Targets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for determining the angular position of a rotating shaft in turbine engines suffer from poor angular fidelity, particularly in blade stress tests and rig builds, due to reliance on 1/rev or multi-tooth sensors and time of arrival estimates.
Innovation Solution
A system utilizing proximity sensors to measure the gap between a rotating target surface of varying radius and a stationary sensor, correlating the gap change to angular change, with optional secondary sensors for variance detection and low-pass frequency filtering to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 1/rev or multi-tooth sensors are used to determine angular position, then the system is simple to implement, but the measurement precision is poor
Solution Approach 1:
The patent replaces conventional mechanical toothed sensors with a non-contact proximity sensor system. The varying radius target profile interacts with the proximity sensor to generate angular position information without mechanical contact, eliminating the need for complex toothed wheel mechanisms while achieving superior angular resolution in the tenths of a degree range.
Solution Approach 2:
The patent transforms the measurement approach by changing from discrete tooth-based signals to continuous proximity-based measurements. The varying radius target creates continuous changes in proximity sensor output as the shaft rotates, providing high-resolution angular information through analog parameter variation rather than discrete mechanical features.
2Measurement precision
If time of arrival estimates are used for angular measurement, then the system is simple, but the angular fidelity is poor
Solution Approach 1:
The patent replaces time-based arrival estimation with spatial-based proximity measurement. The varying radius target profile directly modulates the proximity sensor signal according to angular position, eliminating the need for complex time-correlation algorithms and providing immediate angular position information with high fidelity.
3Measurement precision
If multiple sensors are added to detect variance and improve accuracy, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent introduces a varying radius target profile as an intermediary element between the shaft and the proximity sensor. This target acts as a mechanical encoder that translates rotational position into varying gap distances, allowing a single proximity sensor to achieve the functionality of multiple sensors through the geometric encoding provided by the non-circular target.
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 high-accuracy, non-contact measurement of rotational angular position with tenths of a degree precision, minimizing errors from wobble, vibration, and thermal growth.
Implementation Method 1
a sensor configured to measure a distance between the sensor and an outer surface of the target
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A system (100; 300; 500) includes a shaft (305) configured to rotate about an axis (325). The system (100; 300; 500) also includes a target (310) coupled to the shaft (305) and having a radius that varies around a circumference of the target (310). The system (100; 300; 500) further includes a sensor (315) configured to measure a distance between the sensor (315) and an outer surface (330) of the target (310). In addition, the system (100; 300; 500) includes at least one processing device (202) configured to receive at least one distance measurement from the sensor (315) and determine a rotational angular position of the shaft (305) based on the at least one distance measurement and known profile data of the target (310).