Multi-Periodic Magnetic Position Sensor for Automotive Steering
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Solution Overview
Problem
Current magnetic position sensors for automotive steering columns face challenges in achieving high precision and reliability over multiple turns, with existing solutions often relying on mechanical reducers that introduce friction, complexity, and increased cost, while also requiring power to maintain position memory.
Innovation Solution
A contactless magnetic position sensor system utilizing a magnetized unit with sinusoidal magnetic field components measured by a first magnetosensitive probe for absolute position and a second probe for incremental rotation counting, allowing for precise angle determination without mechanical parts and power supply, enabling True Power On operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical reducers are used to achieve multi-turn position sensing, then the measurement range is extended, but friction and mechanical wear increase reducing reliability
Solution Approach 1:
The patent replaces mechanical reducers with a magnetic field-based sensing system. A magnetized unit with sinusoidal magnetization pattern generates magnetic field components that are detected by magnetosensitive probes, eliminating mechanical contact and friction while achieving multi-turn position sensing through magnetic field periodicity.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the moving part (magnetized unit) and the sensing system (probes). The magnetic field carries position information without requiring mechanical contact, allowing the magnetized unit to rotate multiple times while the probes remain stationary and contactless.
2Measurement precision
If mechanical reducers are used for multi-turn sensing, then the measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent substitutes complex mechanical reducer structures with a simplified magnetic sensing approach. The magnetized unit with its sinusoidal magnetization pattern inherently encodes multi-turn position information in the magnetic field, which is directly detected by the probes without requiring mechanical reduction gears or linkages.
Solution Approach 2:
The patent changes the magnetization parameters of the magnetized unit, specifically creating a sinusoidal magnetization pattern with a specific period. This parameter change allows the magnetic field to naturally encode multi-turn position information, replacing the need for mechanical reducers with a field-based encoding scheme.
3Measurement precision
If power is supplied to maintain position memory, then the position accuracy is maintained, but energy consumption increases
Solution Approach 1:
The patent makes the sensing system self-powered by using the motion of the magnetized unit itself to generate the measurement signals. The magnetosensitive probes detect the magnetic field components generated by the moving magnetized unit, converting the kinetic energy of the moving part directly into measurement signals without requiring external power for the sensing operation.
Solution Approach 2:
The patent replaces powered memory systems with a passive magnetic field-based position encoding system. The position information is continuously encoded in the magnetic field generated by the magnetized unit, allowing the system to maintain position accuracy without active power consumption for memory retention.
4Reliability
If contactless magnetic sensing is used, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise magnetization parameters for the magnetized unit, including the sinusoidal magnetization pattern and its period. By carefully controlling these magnetization parameters during manufacturing, the system achieves reliable contactless sensing while managing the precision requirements through field-based encoding rather than mechanical tolerances.
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 solution provides high precision and reliability over multiple turns with reduced cost and complexity, eliminating mechanical parts and power requirements, thus enhancing the sensor's accuracy and lifespan.
Implementation Method 1
the magnetized unit producing in the vicinity of the first magnetosensitive probe a magnetic field having a normal component and at least one tangential or transverse component, varying sinusoidally and periodically over N periods
Data Source
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AI summary
The invention relates to a magnetic position sensor comprising at least one permanent magnet. The invention also relates to a magnetic device for detecting a torque between a first shaft and a second shaft that are connected via a torsion bar. The aim of the invention is to provide a device for determining the multi-periodic absolute position of a magnetized unit. The subject of the invention is therefore a magnetic position sensor (A) comprising at least the following: a magnetized unit (1), a first magnetosensitive probe (2) and a second magnetosensitive probe (3). The second magnetosensitive probe (3) is capable of measuring a number of complete rotations of the magnetic field in an absolute, incremental and reversible manner so as to determine a second datum relating to the position of the magnet (1), whether or not this second magnetosensitive probe (3) is powered. The sensor further includes a module for calculating the absolute position of the magnet (1) on the basis of the first and second data coming from the first and second probes (2, 3) respectively.