Steering Torque Sensor With Offset Sensors For Interference Rejection
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Solution Overview
Problem
Existing devices for determining steering torque in motor vehicles are prone to interference from magnetic fields, which can affect the accuracy of torque measurements.
Innovation Solution
A device comprising a first and second shaft connected via a twistable means, with multi-pole magnetic means and sensors arranged to measure magnetic flux densities in opposite directions, and a rotational offset of the second sensor relative to the first to reduce interference fields, allowing for precise calculation of steering torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are arranged to measure magnetic flux density in a single direction, then the device complexity is reduced, but measurement precision deteriorates due to interference from magnetic fields in other directions
Solution Approach 1:
The patent applies dimensionality change by adding a second sensor that measures magnetic flux density in a direction perpendicular to the first sensor. This transforms the measurement from a single-dimensional approach to a two-dimensional approach, enabling the system to capture magnetic field components in multiple directions. The two measurement vectors are then combined through vector subtraction to eliminate interference fields and isolate the steering torque signal, thereby improving measurement precision without excessively increasing device complexity.
2Measurement precision
If multiple sensors are added to reduce interference fields, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the stator into multiple stator elements (first, second, third, and fourth stator elements) arranged around the magnetic means. Each stator element is associated with specific sensors that measure magnetic flux density in particular directions. This segmentation allows the system to selectively measure and process magnetic field components from different spatial locations and orientations, improving measurement precision while organizing the complexity into manageable, modular components.
3Area of stationary object
If sensors are positioned close to the magnetic means for compact design, then device compactness improves, but measurement precision deteriorates due to increased interference from other magnetic fields
Solution Approach 1:
The patent positions sensors in multiple spatial dimensions around the magnetic means, with sensors arranged to measure magnetic flux density in perpendicular directions. By utilizing three-dimensional spatial arrangement rather than simply increasing distance in one direction, the system maintains compactness while achieving superior interference rejection. The multi-directional sensor placement enables vector-based interference cancellation, allowing compact design without sacrificing measurement precision.
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 effectively reduces interference fields, enhancing the accuracy of steering torque measurement and simplifying the design and construction of the stator elements, while maintaining operational efficiency.
Implementation Method 1
The first sensor means is designed for measuring a first magnetic flux density in a first direction in the case of a relative rotary movement of the magnetic means relative to the stator means
Implementation Method 2
In a twisted state, an elastic self-aligning torque acts on the means of connection in the direction of the non-twisted state. This can be, for example, a torsion bar.
Data Source
AI summary
A device is provided for determining a steering torque in a motor vehicle. The device includes a first shaft, a second shaft, a twistable connector, a stator, a multipole magnet, a first sensor, and a second sensor. The first shaft is connected to the second shaft via the twistable connector, and the magnet is fixed to the first shaft. The stator is fixed to the second shaft, and the first sensor is designed for measuring, in the case of a relative rotary movement of the magnet relative to the stator, a first magnetic flux density in a first direction. The second sensor is designed for measuring a second magnetic flux density in a second direction. The second direction is opposite to the first direction, and the second sensor is arranged to be rotationally offset by more than 90° relative to the first sensor.