Magnetostrictive Torque Sensor Gain Adjustment
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Solution Overview
Problem
Conventional magnetostrictive torque sensors in electric power steering systems face challenges in manufacturing, including nonuniformities in gain due to variations in heating temperatures and torque applied during anisotropy creation, leading to sensors with reduced rigidity, linearity, and increased complexity in production.
Innovation Solution
A method involving the use of magnetostrictive parts with magnetic anisotropy, detection coils, and a gain adjuster in the detection circuit to compensate for variations, allowing for the production of sensors with high rigidity and linearity, and simplifying the manufacturing process by adjusting the gain post-installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetostrictive films are heated while torque is applied to create magnetic anisotropy, then the sensor can detect steering torque, but variations in heating temperature and applied torque cause non-uniform gain and reduced linearity
Solution Approach 1:
The patent changes the operational parameters of the magnetostrictive torque sensor by introducing a variable gain adjuster that can dynamically adjust the gain based on the detected torque magnitude. This allows the sensor to compensate for non-uniform gain characteristics caused by manufacturing variations, thereby improving detection accuracy without requiring extremely precise manufacturing control
Solution Approach 2:
The patent implements a feedback mechanism where the detection circuit monitors the output signal and feeds it back to the gain adjuster. The gain adjuster then adjusts the amplification level based on the detected signal characteristics, creating a closed-loop system that compensates for manufacturing variations and maintains consistent detection performance
2Ease of manufacture
If conventional manufacturing methods are used without gain adjustment, then the assembly process is simpler, but product non-uniformities require pre-sorting and reduce productivity
Solution Approach 1:
The patent enables the magnetostrictive torque sensor to self-adjust its gain characteristics through the variable gain adjuster and detection circuit. Each sensor unit independently compensates for its own manufacturing variations, eliminating the need for external sorting or manual adjustment processes, thereby improving both assembly simplicity and mass production efficiency
Solution Approach 2:
The patent introduces dynamic gain adjustment capability to the sensor system, allowing the gain to vary based on operating conditions rather than being fixed during manufacturing. This dynamic adaptation enables mass production of sensors with a wider tolerance range while maintaining consistent performance, thereby improving productivity without sacrificing ease of manufacture
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 approach results in magnetostrictive torque sensors with improved rigidity, linearity, and reduced nonuniformities among individual sensors, enhancing steering comfort and simplifying the manufacturing and distribution process.
Implementation Method 1
Magnetostrictive effects are generated in the magnetostrictive films 302, 303 in accordance with this stress
Implementation Method 2
an exciting coil 304 disposed in proximity to the magnetostrictive films 302, 303
Implementation Method 3
the change in magnetic field caused by the magnetostrictive effects of the magnetostrictive films 302, 303 is detected by the detecting coils 306, 307 as a change in impedance
Data Source
AI summary
A method for manufacturing a magnetostrictive torque sensor device includes the steps of: providing a steering shaft or another such rotating shaft with two magnetostrictive parts endowed with magnetic anisotropy; disposing detection coils around the magnetostrictive parts to detect changes in magnetostrictive characteristics of the magnetostrictive parts; providing a detection circuit for bringing out detection signals from signals outputted from the detection coils; and adjusting a gain of a gain adjuster included in the detection circuit.