Sinusoidal Sensor Wheel for Absolute Position Detection
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Solution Overview
Problem
Existing sensor systems for detecting rotation characteristics of rotating elements, such as camshafts, face challenges in achieving continuous position detection and absolute position determination, especially at power-on, and are sensitive to magnetic interference, requiring complex algorithms and being influenced by mechanical tolerances.
Innovation Solution
A sensor system comprising a sensor wheel with a sinusoidal-shaped coil arrangement, including an excitation coil and receiver coils, which generates sinusoidal signals to determine the angular position through demodulation and evaluation, allowing for absolute position detection at power-on and reduced sensitivity to magnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall sensors or incremental encoders are used for rotation detection, then the system can detect rotation characteristics, but absolute position determination at power-on is not possible and the system requires complex algorithms for position calculation
Solution Approach 1:
The patent replaces complex electronic algorithms with a simplified electromagnetic measurement system. By using a sinusoidal sensor wheel profile with raised cosines and orthogonal coil arrangements, the system directly generates position information through electromagnetic induction, eliminating the need for complex software algorithms to calculate position from discrete tooth flank interruptions.
Solution Approach 2:
The patent changes the physical parameter of the sensor wheel from discrete teeth to a continuous sinusoidal profile with raised cosines. This parameter change enables the generation of orthogonal sine and cosine signals that directly represent angular position, simplifying the measurement system while maintaining high precision.
2Reliability
If tooth flank interruption methods are used, then rotation speed can be measured, but continuous position detection is not available especially during start-up
Solution Approach 1:
The patent implements preliminary action by providing absolute position information immediately at power-on through the sinusoidal profile's continuous signals. The raised cosines ensure that valid position information is available from the first measurement point, eliminating the time delay associated with waiting for multiple tooth flanks to pass in incremental systems.
Solution Approach 2:
The sinusoidal sensor wheel profile with raised cosines provides continuous position information throughout the entire rotation cycle, including during start-up. The continuous nature of the sinusoidal signals ensures uninterrupted position detection, unlike discrete tooth-based systems that require multiple interruptions to calculate position.
3Measurement precision
If conventional magnetic sensors are used, then rotation characteristics can be detected, but the system exhibits high sensitivity to magnetic interference fields
Solution Approach 1:
The patent introduces a magnetic shield as an intermediary element between the sensor system and external magnetic interference fields. This shield blocks or attenuates external magnetic influences while allowing the system's own magnetic field to function normally, thereby protecting the measurement system from harmful interference.
Solution Approach 2:
The patent converts the potentially harmful effect of magnetic fields by using a controlled magnetic circuit design where the measurement field is confined and shielded. The system transforms external magnetic interference from a harmful factor into a manageable parameter through strategic placement of magnetic shielding materials.
4Ease of manufacture
If discrete tooth flanks are used on the sensor wheel, then the structure is simple, but mechanical tolerances significantly affect measurement accuracy
Solution Approach 1:
The patent changes the sensor wheel profile parameter from discrete teeth to a continuous sinusoidal waveform with raised cosines. This parameter change makes the system inherently more tolerant of mechanical variations because the continuous sinusoidal profile averages out small manufacturing imperfections, reducing the impact of mechanical tolerances on measurement accuracy.
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 sensor system simplifies the calculation of rotation characteristics, enhances reliability, reduces magnetic interference sensitivity, and allows for precise angular position detection with improved mechanical tolerance tolerance and cost-efficiency, enabling true-power-on functionality and expanded measurement range.
Implementation Method 1
an inductive position sensor (124) having a coil arrangement (126), in particular having at least one excitation coil and at least two receiver coils
Data Source
AI summary
A sensor system for determining at least one rotation characteristic of an element rotating about at least one rotation axis includes at least one sensor wheel having a profile and being connectable to the rotating element; and at least one inductive position sensor including at least one coil arrangement that includes at least one excitation coil and at least two receiver coils, where at least in sections of the at least two receiver coils have a sinusoidal shape.