Torque Sensor Abnormality Detection via Asymmetric Magnetic Sensors
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Solution Overview
Problem
Existing torque sensors with two magnetic sensors cannot determine which sensor has an abnormality, leading to failure in detecting torque when an abnormality occurs in one of the sensors.
Innovation Solution
A torque sensor design incorporating three magnetic sensors, where one is placed symmetrically to the magnetic environment of the other two, allowing for detection of torque even if one sensor is abnormal by comparing output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two magnetic sensors are used for torque detection, then the device complexity is reduced, but the reliability deteriorates because the system cannot identify which sensor has an abnormality when one fails
Solution Approach 1:
The patent applies local quality by positioning the three magnetic sensors at different locations with different magnetic environments. Specifically, the first magnetic sensor is positioned at a first location, the second at a second location, and the third at a third location, where each sensor experiences a unique magnetic field distribution. This spatial differentiation allows the system to identify which specific sensor has failed by comparing the output signals, thereby maintaining reliability while using a minimal number of sensors.
2Reliability
If three magnetic sensors are used for torque detection, then the reliability is improved by enabling abnormality identification, but the device complexity increases
Solution Approach 1:
The patent implements partial action by using exactly three magnetic sensors - the minimum number required to achieve sensor failure identification. With three sensors positioned at different locations, the system can detect torque while identifying which specific sensor has failed. This is the smallest configuration that enables abnormality detection, avoiding excessive sensor usage while achieving the reliability improvement goal.
3Reliability
If multiple magnetic sensors are used with different magnetic environments, then the ability to identify abnormal sensors is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies asymmetry by intentionally designing the magnetic sensor positions to experience different magnetic environments. The first magnetic sensor is positioned at a first location, the second at a second location, and the third at a third location, where each position creates a distinct magnetic field exposure. This asymmetric positioning ensures that when a sensor fails, its unique magnetic environment signature allows identification of the failed sensor, while the asymmetric design is robust to manufacturing variations.
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
Enables continuous torque detection and control in electric power steering systems by identifying and isolating abnormal sensors, improving accuracy and stability.
Implementation Method 1
a first magnetic sensor provided between a first magnetic collection mechanism and the second magnetic collection mechanism
Data Source
AI summary
A torque sensor is configured to detect torque even when an abnormality has occurred in one magnetic sensor among multiple magnetic sensors. An electric power steering apparatus using the torque sensor is provided. The torque sensor includes a first magnetic sensor between a first magnetic collection mechanism and a second magnetic collection mechanism, a second magnetic sensor between the first and second magnetic collection mechanisms and disposed at a same position as or a symmetric position to a magnetic environment of the first magnetic sensor, and a third magnetic sensor between the first and second magnetic collection mechanisms and disposed at a same position as or a symmetric position to the magnetic environments of the first and second magnetic sensors. The torque sensor detects torque generated on a rotational member based on an output signal of the first, second, or third magnetic sensor.