Magnetostrictive Torque Sensor With Insulating Layer
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Solution Overview
Problem
Magnetostrictive torque sensors face challenges in maintaining high sensitivity and stability due to magnetism from the torque transmission shaft and external sources, which affects the accuracy of steering torque detection in electric power steering systems.
Innovation Solution
Incorporating magnetically insulating layers made of nonmagnetic materials between the operating shaft and the magnetostrictive films, preventing magnetic interference and allowing for improved sensitivity and stability of the sensor signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat treatments or surface treatments are performed on the pinion to increase mechanical strength, then the pinion can transmit greater steering torque, but the torque transmission shaft becomes easily magnetized which reduces sensor stability
Solution Approach 1:
A magnetically insulating layer is introduced as an intermediary between the torque transmission shaft and the magnetostrictive film. This layer prevents magnetic flux from the shaft from reaching the film, thereby isolating the sensor from magnetic interference while allowing the shaft to undergo necessary heat treatments for strength
2Device complexity
If the magnetostrictive film is placed directly on the torque transmission shaft to detect steering torque, then the sensor structure is simple, but the film is affected by magnetism from the shaft and external sources reducing measurement precision
Solution Approach 1:
The magnetically insulating layer serves as a mediator that separates the magnetostrictive film from the magnetic field source (torque transmission shaft). This allows the film to detect only the magnetic field changes caused by torsion, improving measurement precision while adding minimal structural complexity
3Device complexity
If the magnetostrictive film is exposed to magnetic fields from the torque transmission shaft and external sources, then the sensor can be kept simple in configuration, but the sensitivity and stability of magnetostrictive properties deteriorate
Solution Approach 1:
The magnetically insulating layer acts as a protective intermediary that shields the magnetostrictive film from unwanted magnetic fields while allowing the sensor to maintain its relatively simple overall configuration. This layer enables the film to respond only to torsion-induced magnetic changes
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 enhances the sensitivity and stability of magnetostrictive properties, enabling precise and stable detection of steering torque, even under increased load conditions, and provides design flexibility by isolating the magnetostrictive films from magnetic influences.
Implementation Method 1
a magnetostrictive film is formed on an external peripheral surface of the torque transmission shaft. The magnetostrictive torque sensor makes it possible to detect a steering torque by using an electric coil and a magnetostriction sensor circuit to detect changes in magnetostriction that occur in the magnetostrictive film in accordance with the steering torque.
Implementation Method 2
at least one magnetically insulating layer provided on an outer peripheral surface of the operating shaft; and at least one magnetostrictive film provided on an outer peripheral surface of the magnetically insulating layer, wherein the magnetically insulating layers are formed of a nonmagnetic material
Data Source
AI summary
A magnetostrictive torque sensor for detecting a torque includes an operating shaft, magnetically insulating layers, and magnetostrictive films. The operating shaft is adapted to be applied with an external torque. The magnetically insulating layers are formed of a nonmagnetic material and provided on an outer peripheral surface of the operating shaft. The magnetostrictive films are provided on outer peripheral surfaces of the magnetically insulating layers.