Torque Sensor With Distinct Magnetic Sensors For Short Circuit Detection
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Solution Overview
Problem
Existing torque sensors in electric power steering systems face challenges in accurately determining failures, such as short circuits in signal lines, which can lead to erroneous torque detection and discomfort for drivers due to unstable steering assistance.
Innovation Solution
A torque sensor design with three magnetic sensors having distinct output characteristics, independent power and ground lines, allows for the detection of short circuits and failures by comparing outputs, ensuring continued accurate torque detection and steering assistance even in anomalous conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two magnetic sensors are arranged along the circumference of the magnetism collection ring with common power and ground lines, then torque detection is enabled, but failure determination becomes insufficient when short circuits occur in signal lines
Solution Approach 1:
The patent applies local quality by making each magnetic sensor have distinct output characteristics (different gains or offsets) rather than using identical sensors. This allows the ECU to identify which sensor has failed by comparing outputs, since a failed sensor will show abnormal output patterns that differ from the expected characteristics. The distinct characteristics are locally applied to each sensor to enable failure detection.
Solution Approach 2:
The patent segments the power supply system by providing independent power lines and ground lines to each magnetic sensor. This segmentation allows the ECU to determine whether a failure is due to sensor malfunction or signal line short circuit by checking which sensor's power/ground lines are affected. Each sensor's power and ground connections are separated to enable localized failure diagnosis.
2Measurement precision
If magnetic sensors with identical characteristics are used, then device simplicity is maintained, but accurate failure determination becomes impossible when short circuits occur
Solution Approach 1:
The patent applies local quality by making each magnetic sensor have distinct output characteristics (different gains or offsets) rather than using identical sensors. This allows the ECU to identify which sensor has failed by comparing outputs, since a failed sensor will show abnormal output patterns that differ from the expected characteristics. The distinct characteristics are locally applied to each sensor to enable failure detection.
3Reliability
If common power and ground lines are used for all magnetic sensors, then wiring simplicity is maintained, but failure determination cannot distinguish between sensor failure and signal line short circuit
Solution Approach 1:
The patent segments the power supply system by providing independent power lines and ground lines to each magnetic sensor. This segmentation allows the ECU to determine whether a failure is due to sensor malfunction or signal line short circuit by checking which sensor's power/ground lines are affected. Each sensor's power and ground connections are separated to enable localized failure diagnosis.
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 design effectively identifies and mitigates short circuits and sensor failures, preventing erroneous torque detection and ensuring stable steering assistance by using the outputs from functioning sensors, thus enhancing driver comfort and system reliability.
Implementation Method 1
a cylindrical magnet that rotates integrally with the first shaft; a pair of magnetic yokes that rotate integrally with the second shaft
Implementation Method 2
three magnetic sensors that respectively detect a change in magnetic flux of the magnetic yokes for calculating torque applied to the first and second shafts
Data Source
AI summary
A torque sensor includes a first shaft, a second shaft that is coaxially linked to the first shaft, a cylindrical magnet that rotates integrally with the first shaft, a pair of magnetic yokes that rotate integrally with the second shaft, and three magnetic sensors that respectively detect a change in magnetic flux of the magnetic yokes for calculating torque applied to the first and second shafts. Output characteristics of the three magnetic sensors are different from each other.