Eddy Current Sensor Asymmetry for Turbocharger Speed Detection
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Solution Overview
Problem
Existing sensor devices for detecting rotational properties, such as rotational speed of compressor wheels in turbochargers, face challenges due to high signal frequency complexity and limited measuring effectivity, requiring complex signal processing and being unsuitable for robust measurement acquisition in small, confined spaces.
Innovation Solution
A sensor device comprising a first and second element, where the first element is stationary and the second element is rotatable, with a field generator and field sensor arranged to generate and detect eddy currents, utilizing offset and angularly asymmetrical design to vary electromagnetic properties, allowing for precise detection of rotational properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small sensor device is used to accommodate limited space, then the device size is reduced, but the measurement effect is limited and signal processing complexity increases
Solution Approach 1:
The patent applies asymmetry by creating an angularly asymmetric magnetic field distribution through the specific arrangement of permanent magnets and ferromagnetic structures. This asymmetric field configuration generates distinctive eddy current patterns that vary with angular position, enabling simplified signal processing while maintaining compact sensor dimensions. The asymmetric design allows the sensor to detect rotational properties through characteristic signal variations without requiring complex processing algorithms.
2Reliability
If the air gap tolerance is kept small for robust measurement, then measurement reliability is improved, but the device complexity and signal processing requirements increase
Solution Approach 1:
The patent implements preliminary action by pre-configuring the magnetic field geometry through specific permanent magnet arrangements and ferromagnetic structures before the measurement process begins. This pre-established asymmetric magnetic field pattern ensures that eddy currents are generated with distinctive angular variations, allowing for robust measurement even with small air gap tolerances. The preliminary magnetic field configuration eliminates the need for complex real-time signal processing to achieve reliable measurements.
3Speed
If the signal frequency is high due to proportional relationship with compressor blade number, then rotational speed detection capability is improved, but signal processing complexity increases
Solution Approach 1:
The patent replaces complex mechanical signal processing with electromagnetic field-based detection. By using the asymmetric magnetic field to generate angularly varying eddy currents, the system converts rotational speed information into characteristic field pattern variations. This substitution allows high-frequency signals corresponding to high rotational speeds to be detected through simplified electromagnetic sensing rather than complex mechanical or electronic signal processing systems.
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 signal processing complexity and enhances measurement robustness by varying the eddy current field based on angular position, enabling accurate detection of rotational properties like rotational speed with improved signal clarity.
Implementation Method 1
The field generator (120) is configured to generate at least one eddy current (154) at at least one location of the second element (134)
Implementation Method 2
the field sensor (122) is configured to detect at least one field generated by the eddy current (154)
Data Source
Figure 1A~2
AI summary
The sensor device (110) has two elements (132,134) that are rotated about a rotation axis (136) relative to each other, where the elements are connected to a field generator (120). The field generator is arranged to a location of the latter element to produce the eddy current. The latter element is adapted to the field generated by the eddy current. An independent claim is also included for a compressor for compressing fluid media.