Eddy Current Angle Sensor for Deflected Shafts
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Solution Overview
Problem
Existing angle sensors face issues with low measurement accuracy, susceptibility to damage, bulkiness, and difficulty in maintaining contact with rotating shafts, especially when the shaft deflects, and require strict coaxial alignment, making them unsuitable for high-speed applications and environments with dust or vibration.
Innovation Solution
An angle sensor utilizing a gear structure with an eddy current probe and processing unit, where the eddy current probe faces gear teeth and tooth grooves, allowing for feature angle recognition and outputting precise angle measurement signals without the need for calibration, even with deflected rotating shafts, and can operate in harsh environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal ring is fixed on the rotating shaft for eddy current sensing, then angle measurement can be performed, but the mass distribution becomes non-uniform causing shaft deflection
Solution Approach 1:
The patent extracts the sensing function from a separate metal ring and integrates it directly into the gear structure. The gear teeth themselves serve as the eddy current sensing target, eliminating the need for an additional metal ring that would cause mass distribution issues and shaft deflection.
Solution Approach 2:
The patent combines the gear structure with the eddy current sensing function. The gear teeth and tooth grooves serve dual purposes: mechanical transmission and angle measurement target, merging two separate components into one integrated structure.
2Measurement precision
If the field coil and detection coil are fixed to separate structures with strict relative position requirements, then eddy current sensing can be performed, but the device becomes bulky and difficult to mount
Solution Approach 1:
The patent merges the field coil and detection coil into a single integrated eddy current probe assembly. This unified structure eliminates the need for strict relative positioning between separate coils and simplifies mounting to just one component rather than multiple precisely aligned parts.
Solution Approach 2:
The eddy current probe is designed as a self-contained unit that performs both field generation and detection functions, making it a universal component that can be mounted independently without requiring separate positioning structures for each coil.
3Productivity
If contact angle sensors use ball switches triggered by rotation, then angle measurement is achieved, but the sensor is easily damaged and can only test low-speed rotation
Solution Approach 1:
The patent replaces the mechanical ball switch contact system with a non-contact eddy current sensing system. The eddy current probe detects gear tooth passage through electromagnetic induction without physical contact, eliminating mechanical wear and enabling high-speed measurement while maintaining reliability.
4Measurement precision
If Hall angle sensors require strict coaxial alignment with clearance less than 0.5 mm, then measurement accuracy is maintained, but the sensor cannot handle deflected rotating shafts
Solution Approach 1:
The patent employs a dynamic eddy current sensing approach where the probe continuously tracks the gear structure's position. The system adapts to shaft deflection by measuring relative position changes between the probe and gear teeth, maintaining accuracy even when the shaft axis shifts during operation.
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 solution provides high-precision angle measurements with ±0.1° accuracy, is resistant to shaft deflection, and simplifies mounting and maintenance, enabling operation in diverse environments without the need for calibration, while being compact and efficient.
Implementation Method 1
the field coils sense that an eddy current field generated by the metal ring 51 varies, and then the variation of the eddy current field is calculated by using backend processing equipment such as the hardware circuit 54
Data Source
AI summary
Disclosed is an angle sensor, including a gear structure (1), an eddy current probe (2) and a processing unit (3), wherein the gear structure (1) is a gear mounted and fixed on the outer circumference of a rotating shaft or a gear formed by machining on the outer circumference of the rotating shaft, and a positioning structure (P) for feature angle recognition is provided on an outer circumferential side of the gear structure (1); the eddy current probe (2) is positioned at the outer circumferential side of the gear structure (1), and the eddy current probe (2) faces a gear tooth and a tooth groove of the gear; and the processing unit (3) is connected to the eddy current probe (2) and is used for processing signals and outputting an angle measurement signal. Also disclosed is an angle measurement method.