Circular Magnetostrictive Rotary Encoder for Compact Angle Detection
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Solution Overview
Problem
Existing rotary encoders for detecting the angle of rotation of a shaft are not robust and cost-effective, limiting their application in industrial settings where space-saving and accurate measurements are crucial.
Innovation Solution
A rotary encoder design utilizing a magnetostrictive principle with a circularly bent waveguide, multiple position magnets, and a measuring transducer that ignores signals from overlapping areas to ensure accurate angle determination, allowing for flexible adaptation to different shaft diameters and providing redundant position signals for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear magnetostrictive measuring principle is used for rotary encoders, then position detection capability is achieved, but the device becomes bulky and complex
Solution Approach 1:
The waveguide is bent into a circular shape that can be arranged around the encoder shaft, replacing the conventional linear waveguide structure. This curvature adaptation enables the magnetostrictive measuring principle to function in a rotary application while maintaining a compact and simple device structure, directly resolving the contradiction between achieving position detection and avoiding structural complexity
2Volume of moving object
If the waveguide is bent into a circular shape with overlapping ends, then space-saving compact design is achieved, but electrical contact at the overlapping area may occur
Solution Approach 1:
An insulating element is introduced as an intermediary component at the overlapping area of the circular waveguide. This insulating element prevents direct electrical contact between the waveguide ends while allowing the mechanical and magnetic functions to continue, thus enabling the compact circular design without the harmful effect of electrical contact interference
3Measurement precision
If multiple position magnets are used spaced at equal angular distances, then measurement accuracy is improved through signal comparison, but device complexity increases
Solution Approach 1:
The transducer is designed with localized signal evaluation capabilities that can distinguish and process signals from multiple position magnets based on their specific angular positions. By implementing position-specific signal processing, the system can utilize multiple magnets for improved measurement accuracy while the transducer's localized processing prevents overall system complexity from increasing proportionally
4Quantity of substance
If the transducer processes all signals from position magnets including those at overlapping areas, then signal reception is maximized, but angle determination accuracy decreases
Solution Approach 1:
The transducer is designed to extract and process only the relevant signals from position magnets, specifically excluding signals from magnets located at the overlapping area of the circular waveguide. This selective signal extraction ensures that only high-quality, unambiguous signals are used for angle determination, maintaining measurement precision while still utilizing multiple position magnets for improved accuracy
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 results in a robust, space-efficient rotary encoder capable of precise angle measurement with clear distinction between position magnets, adaptable to various shaft diameters, and ensuring accurate single-turn and multi-turn measurements.
Implementation Method 1
A magnetic field is created by means of an electrical impulse, which propagates along the waveguide
Implementation Method 2
A position magnet causes a mechanical impulse with its magnetic field together with the generated magnetic field, which is generated on the waveguide
Implementation Method 3
The mechanical impulse is detected by the transducer, with an absolute position of the position magnet being calculated from a time difference
Data Source
Figure 1~2
AI summary
To enable a robust and simply constructed rotary encoder for detecting a rotation angle of an encoder shaft, a rotary encoder is provided comprising a waveguide (2) made of magnetostrictive material, a transducer (3) at a first end of the waveguide (2) for coupling a current pulse into the waveguide (2) and for detecting a mechanical pulse guided by the waveguide (2) in the direction of the transducer (3), a damping element at a second end of the waveguide (2) for damping a mechanical pulse propagating in the direction of the second end, and at least two position magnets (4a, 4b) spaced apart at a predetermined angle, which are attached to the encoder shaft (W) and rotate with the encoder shaft (W), wherein the waveguide (2) is bent into a circular shape and arranged around the encoder shaft (W).that a circle with an overlap region (UB) is formed between the first and the second end of the waveguide (2), and the at least two position magnets (4a, 4b) move at a fixed distance and on a path to the circularly curved waveguide (2), the path being located in a plane (E).