Rotational Angle Detection Using Magnetic Field Separation
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Solution Overview
Problem
Existing systems for contactless detection of rotational angles in rotatable elements require spatial integration of internal evaluation units and are prone to accuracy loss due to contamination, leading to increased manufacturing and assembly costs, as well as reduced robustness.
Innovation Solution
A device that detects rotational angles without the need for internal evaluation units, utilizing a magnet with a multipole design and two sensors positioned to detect the magnetic field, allowing for phase-shifted output signals to determine direction and increasing resolution without extensive design changes, while using a printed circuit board for logical operations and error recognition, and incorporating mechanical stability features like bending regions and snap hooks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If internal evaluation units are integrated into the sensor to compute absolute steering angle, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the evaluation unit from the sensor assembly and relocates it to a separate control unit. The sensor only detects magnetic field signals and transmits them to the control unit for processing. This separation eliminates the need for spatial integration of complex evaluation units within the sensor, reducing device complexity while maintaining measurement precision through centralized processing.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the rotatable element and the sensor. Instead of direct mechanical contact or integrated electronics, the magnetic field transmits rotational position information wirelessly to the sensor, which then transmits electrical signals to the control unit. This intermediary approach eliminates the need for physical integration of evaluation units.
2Measurement precision
If optical measuring elements are used for rotational detection, then measurement precision is improved, but reliability deteriorates due to contamination
Solution Approach 1:
The patent replaces optical measuring elements with a magnetic field-based detection system. A magnet is attached to the rotatable element, and magnetic sensors detect changes in the magnetic field as the element rotates. This substitution eliminates the vulnerability of optical systems to contamination by dust, moisture, and other environmental factors, as magnetic fields are not affected by such contaminants.
Solution Approach 2:
The patent changes the detection parameter from optical properties (light transmission, reflection) to magnetic field properties (field strength, direction). By measuring the magnetic field vector components instead of optical signals, the system achieves contamination resistance while maintaining measurement precision through alternative physical parameters.
3Measurement precision
If multiple sensors are added around the magnet to increase resolution, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent transitions from one-dimensional rotational detection to two-dimensional magnetic field vector detection. By measuring both the radial and tangential components of the magnetic field using a single sensor, the system achieves higher resolution angular detection. This dimensional approach allows precise angle measurement without requiring multiple sensors positioned around the magnet.
Solution Approach 2:
The patent makes a single magnetic sensor perform multiple functions by detecting different components of the magnetic field vector. The same sensor can determine both the magnitude and direction of the magnetic field, enabling full angular resolution without requiring separate sensors for different measurement aspects. This multi-functionality reduces the number of components needed.
4Ease of manufacture
If sensor signal levels are set close to supply voltage or ground, then ease of manufacture is improved, but reliability deteriorates due to difficulty in error detection
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the signal levels from the magnetic sensors and compares them against expected ranges. When signal levels deviate from normal operating parameters, the system generates error signals to indicate sensor malfunctions. This feedback loop enables reliable error detection while allowing flexible signal level configuration during manufacturing.
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 simplifies manufacturing, reduces costs, enhances robustness by eliminating contamination risks, and increases mechanical stability, allowing for precise detection of rotational angles with improved resolution and reduced cabling complexity.
Implementation Method 1
a magnet (10) is situated in the upper, outer circumferential region of an annular or hollow cylindrical hub (16)... which provides the option of placing a sensor (20) at a certain location in the measurable range of the magnetic field
Implementation Method 2
For this purpose a Hall sensor might be used as sensor (20), which emits a binary signal depending on whether its sensitive range is predominantly in the area of influence of a north pole (12) or of a south pole (14)
Data Source
AI summary
A device for detecting a rotational angle of a rotatable part, e.g., a steering wheel, includes at least one magnet, at least one sensor which detects the magnetic field of the magnet, at least one housing in which the sensor and/or the magnet is/are movably situated relative to one another, and at least one printed circuit board which is contacted in an electrically conductive manner by at least one connecting element of the sensor. The printed circuit board has at least one interface or a connector plug from which the output signal of the sensor or an output signal derived therefrom is relayed to an evaluation unit which ascertains the absolute position of the rotational angle as a function of the output signal.