Camshaft Sensor Tooth Front Validation via Speed Variation
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Solution Overview
Problem
Existing methods for validating tooth front detections in camshaft sensors are prone to errors due to high speed variations, leading to widened acceptance tolerances that can confuse interfering peaks with tooth fronts, especially in configurations with short or long teeth and inter-teeth spaces, resulting in loss of discriminating capacity.
Innovation Solution
A processing method that calculates and compares the rotational speed of the camshaft wheel between successive tooth front detections, validating a new tooth front if the speed variation is within specific thresholds, thereby enhancing the robustness of measurement signals without relying on crankshaft sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If temporal and angular indicators with widened tolerances are used to accommodate high speed variations, then the camshaft sensor can tolerate speed variations, but the discriminating capacity is lost and interfering peaks cannot be distinguished from tooth fronts
Solution Approach 1:
The patent applies dynamics by making the validation criteria adaptive rather than static. Instead of using fixed widened tolerances, the system dynamically adjusts validation thresholds based on the immediately preceding tooth period. This allows the system to tolerate speed variations while maintaining discriminating capacity, as the validation criteria evolve with the actual operating conditions rather than relying on predetermined static tolerances.
Solution Approach 2:
The patent changes the parameter used for validation from fixed temporal and angular tolerances to a dynamic reference based on the preceding tooth period. By comparing the current tooth period against the immediately preceding period rather than against fixed tolerance ranges, the system adapts to speed variations while preserving the ability to distinguish valid tooth fronts from interfering peaks.
2Ease of operation
If fixed temporal and angular tolerances are used for tooth front validation, then the validation process is simple, but it cannot adapt to high speed variations and confuses interfering peaks with tooth fronts
Solution Approach 1:
The system transitions from static fixed tolerances to dynamic adaptive validation. The validation criterion becomes the ratio between the current tooth period and the immediately preceding tooth period, allowing the system to automatically adapt to speed variations without complex processing. This dynamic approach maintains detection accuracy while preserving operational simplicity.
Solution Approach 2:
The validation mechanism serves itself by using its own historical data (the preceding tooth period) as the reference for validating the current tooth front. This self-referential approach eliminates the need for external reference data or complex multi-parameter comparisons, achieving both reliability and simplicity through a self-adapting single-criterion validation process.
3Adaptability or versatility
If the acceptance tolerances are greatly widened to adapt to short teeth or inter-teeth spaces, then the sensor can handle varied tooth configurations, but the tolerances become excessively wide for long teeth and inter-teeth spaces, losing discriminating capacity
Solution Approach 1:
The patent applies local quality by making the validation tolerance local to each specific tooth detection event rather than global and fixed. Each tooth front is validated against the immediately preceding tooth period, creating a localized adaptive tolerance that automatically scales to the specific tooth configuration being measured. This eliminates the need for overly wide global tolerances while maintaining adaptability to varied tooth configurations.
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 method improves the reliability of tooth front detection by reducing false positives and negatives, maintaining accurate angular position measurements even under high speed variations, and can be implemented in degraded modes without a functional crankshaft sensor.
Implementation Method 1
the sensing element 3 is able to detect the metal, like a Hall-effect sensor
Data Source
AI summary
The invention relates to a device and a processing method for a camshaft sensor (1) of the type comprising a toothed camshaft wheel (2) and an opposite sensing element (3) able to detect a tooth front, comprising the following steps: detection of a new tooth front (k) by said sensing element; calculation of a rotational speed (Wk) of the camshaft wheel (2) for the new tooth front (k); comparison with the rotational speed (Wk−1) of the camshaft wheel for the preceding tooth front (k−1) detected by said sensing element; if the variation in the rotational speed (Wk) of the camshaft wheel (2) between the new tooth front (k) and the preceding tooth front (k−1) is low, the new tooth front (k) is validated, otherwise the new tooth front (k) is rejected.