Steering Sensor Decoupling Torque Crosstalk
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Solution Overview
Problem
Existing sensor devices with incremental and torque sensor units for steering shafts in motor vehicles experience undesired coupling and interference due to the magnetic fields of permanent magnets, leading to 'crosstalk' between the incremental and torque sensor units.
Innovation Solution
A sensor device with a housing-fixed incremental sensor unit and a shielding element that moves radially during shaft rotation, minimizing interference by avoiding direct interaction with the torque sensor unit's magnetic field, and generating a signal pulse through signal path interruption or attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a permanent magnet is used in the incremental sensor unit to generate signal pulses, then rotational angle position can be detected, but magnetic field interference and crosstalk with the torque sensor unit occur
Solution Approach 1:
The permanent magnet is extracted from the incremental sensor unit and replaced with a non-magnetic transmitting element (such as an optical or electromagnetic transmitter). This removes the source of magnetic field interference while preserving the signal generation function through alternative physical principles.
Solution Approach 2:
A non-magnetic intermediate field (optical or electromagnetic) is introduced as a mediator between the transmitting element and receiving element. This intermediary enables signal transmission without introducing magnetic field interference to the torque sensor unit.
2Measurement precision
If the incremental sensor unit uses a moving permanent magnet relative to a fixed receiving element, then signal pulses are generated upon reaching defined rotational angle positions, but interference with the torque sensor unit's magnetic field occurs
Solution Approach 1:
The mechanical magnetic field interaction system is replaced with a non-contact optical or electromagnetic transmission system. The transmitting element and receiving element communicate through light or electromagnetic waves rather than direct magnetic field interaction, eliminating interference with the torque sensor.
3Device complexity
If both incremental sensor unit and torque sensor unit are integrated in the same sensor device, then space is saved, but crosstalk between the two units occurs
Solution Approach 1:
The magnetic field source (permanent magnet) is extracted from the incremental sensor unit, removing the cause of crosstalk. This allows both sensor units to coexist in the same housing without magnetic interference between them.
Solution Approach 2:
The physical parameter used for signal transmission is changed from magnetic field to optical or electromagnetic field. This parameter change eliminates the harmful magnetic interaction between the incremental sensor unit and torque sensor unit while maintaining integration benefits.
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 design effectively decouples the incremental sensor unit from the torque sensor unit, reducing interference and allowing accurate measurement of rotational angles and torque applied to the steering shaft, enhancing the reliability of steering angle and torque detection.
Implementation Method 1
a transmitting element (41) fixed on the housing (51, 52) and a housing-fixed receiving element (42), wherein a signal emitted by the transmitting element (41) and transmitted along a signal path can be received by the receiving element (42)
Implementation Method 2
the incremental sensor unit (40) is designed to generate a signal pulse upon reaching the defined rotational angle position
Data Source
AI summary
The invention relates to a sensor device (100) having an incremental sensor unit (40, 40′, 40″) for a shaft rotatable about a rotational axis, in particular for a steering shaft of a motor vehicle, wherein the incremental sensor unit (40, 40′, 40″) is designed to acquire at least one defined rotational angle position of the shaft. The incremental sensor unit (40, 40′, 40″) comprises a transmitting element (41, 41″) and a housing-fixed receiving element (42), wherein a signal (MInk_planar) emitted by the transmitting element (41, 41″) and transmitted along a signal path is receivable by the receiving element (42) and it is recognizable on the basis of the signal (MInk_planar) received by the receiving element (42) whether the shaft is located in the defined rotational angle position (δdef) or not. If the shaft reaches the defined rotational angle position (δdef), a signal pulse can be generated. In this case, the transmitting element (41, 41″) is also arranged fixed on the housing, wherein a change of the signal (MInk_planar) can be caused by a rotational movement of the shaft. Furthermore, the invention relates to a motor vehicle having a sensor device (100).