Dual Sensor Loop Angle Sensing Using Magnetostrictive Transit Time
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing angular rotor position measurement methods using magnetic sensors are prone to errors due to magnetic interference, tolerances, and environmental influences, making them difficult to integrate and precise, especially in systems where the angle of a rotating component needs to be measured accurately.
Innovation Solution
A magnetostrictive sensor structure with two sensor loops, each adapted to the movement direction of the rotating component, uses a common transmitting element and separate receiving elements to determine the angular position from the ratio of transit times, eliminating the need for magnetic flux measurement and making the system immune to interference and tolerances by utilizing only the saturation point for pulse reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If magnetic measuring methods are used for angular rotor position measurement, then the measurement can be performed with simple sensor structure, but the measurement precision deteriorates due to magnetic interference, tolerances, and environmental influences
Solution Approach 1:
The patent replaces magnetic field-based measurement with a magnetostrictive wave-based measurement system. A transmitting element generates elastic waves that propagate through a magnetostrictive sensor structure, and a magnet on the rotor reflects these waves. The time-of-flight measurement is immune to magnetic interference while maintaining structural simplicity.
Solution Approach 2:
The patent introduces a magnetostrictive sensor structure as an intermediary medium between the transmitting element and the magnet. This structure converts the interaction into a wave propagation problem through the medium, where the magnet's position is determined by measuring the time for elastic waves to travel through the magnetostrictive material and reflect off the magnet.
2Measurement precision
If magnetic flux measurement is used, then the angular position can be determined, but the system becomes susceptible to magnetic interference and environmental influences
Solution Approach 1:
The patent substitutes magnetic flux measurement with elastic wave propagation measurement through a magnetostrictive medium. The measurement principle changes from detecting magnetic field strength to measuring the time-of-flight of mechanical waves, thereby eliminating susceptibility to magnetic interference while maintaining angular position determination capability.
3Device complexity
If a single sensor loop is used for transit time measurement, then the device complexity is reduced, but the measurement reliability deteriorates due to inability to compensate for directional errors
Solution Approach 1:
The patent divides the measurement system into two separate sensor loops (first and second loops) that measure transit times in opposite rotational directions. Each loop provides independent measurement data, and the combination of both measurements compensates for directional errors and improves overall measurement reliability.
Solution Approach 2:
The patent uses the difference between the two transit time measurements as feedback to detect and correct for runout errors and directional inaccuracies. By comparing the forward and reverse transit times, the system can identify and compensate for systematic errors in the measurement process.
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
This solution enables accurate angular measurement of rotating components, tolerant to tolerances and environmental influences, with the ability to set asymmetric saturation zones and reduce magnetic interference, allowing for precise position determination across a complete revolution.
Implementation Method 1
a magnetostrictive sensor structure, which is coupled to a transmitting and receiving element and along which a magnet secured to the moving component moves
Implementation Method 2
the transmitted signal is reflected at the saturation zone produced by the magnet in the magnetostrictive sensor structure
Data Source
AI summary
A device having two mutually spaced sensor loops is provided. The device includes a magnetostrictive sensor structure coupled to a plurality of transmitters and a plurality of receivers, and along which a magnet that is secured to the rotating component moves. Each sensor loop has a shape corresponding to a rotating direction of the rotating component. Two saturation zones are in both sensor loops. Each transmitting element is provided for simultaneously coupling two current pulses in opposite direction into one respective sensor loop. Each receiving element is positioned to receive a reflected pulse by the magnet at the respective saturation zone. The receiving elements are connected to evaluation electronics configured to for determine an angular position of the rotating component based on transit times for the current pulse to travel along the respective sensor loop from the respective transmitting element to the respective saturation zone and for each reflected pulse to travel along the respective sensor loop from the respective saturation zone to the respective receiving element.