Camshaft Angular Position Detection Using X+1 Tooth Sensor
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Solution Overview
Problem
Existing methods for determining the angular position of a camshaft with an X+1 toothed wheel, characterized by equidistant teeth and an additional tooth, are obsolete due to reduced irregularity and asymmetry, making it difficult to accurately measure the angular position using traditional sensor technologies.
Innovation Solution
A method involving a sensor with a toothed wheel having p teeth distributed at equal angles and an additional tooth, where the angular position is determined by calculating a ratio of time intervals between tooth signals and comparing it to a threshold to identify specific teeth, allowing precise measurement of the camshaft's angular position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an X+1 toothed wheel with equidistant teeth is used, then the manufacturing precision and regularity are improved, but the measurement precision deteriorates due to reduced irregularity and asymmetry
Solution Approach 1:
The patent applies asymmetry by introducing one additional tooth among X equidistant teeth, creating a unique asymmetric pattern. This single asymmetric element (the extra tooth) provides a reference point that enables precise angular position measurement while maintaining the overall symmetry and manufacturing precision of the equidistant tooth arrangement.
Solution Approach 2:
The patent changes the parameter of tooth distribution from purely equidistant to equidistant with one exception. By modifying the tooth distribution pattern to include X equidistant teeth plus one additional tooth at a specific position, the system maintains manufacturing precision while creating measurable asymmetry for accurate angular position detection.
2Measurement precision
If traditional toothed wheels with irregular teeth are used, then the measurement precision is improved due to asymmetry, but the manufacturing precision deteriorates
Solution Approach 1:
The patent introduces controlled asymmetry by adding one tooth to an otherwise symmetric equidistant arrangement. This creates a single asymmetric feature that provides measurement reference without requiring irregular manufacturing of all teeth, thus maintaining high manufacturing precision while enabling accurate measurement.
Solution Approach 2:
The patent modifies the tooth distribution parameter from completely regular to regular with one exception. This parameter change creates sufficient asymmetry for precise measurement while maintaining the manufacturing simplicity and precision of equidistant tooth spacing for the majority of teeth.
3Manufacturing precision
If the number of teeth is increased to reduce irregularity, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The patent segments the toothed wheel structure into two distinct parts: X equidistant teeth that provide regular spacing and one additional tooth that provides asymmetric reference. This segmentation allows the majority of teeth to maintain simple equidistant manufacturing while the single additional tooth provides the necessary complexity for precise measurement without significantly increasing overall device complexity.
Data Source
AI summary
Disclosed is a method for determining the angular position of a shaft by a sensor including a toothed wheel including p teeth distributed at equal angles and an additional tooth and a sensitive element that is able to detect a tooth, including the following steps: receiving a tooth signal and the date thereof; shifting the preceding time intervals: Tn−3←Tn−2, Tn−2←Tn−1, Tn−1←Tn; determining the current time interval according to the formula Tn=tn−tn−1; calculating a ratio according to the formula Rn=(Tn*Tn−3)/(Tn−1*Tn−2); and comparing the ratio with a threshold, if the ratio is greater than the threshold, the current tooth signal corresponds to the second tooth immediately following the first tooth, itself immediately following the additional tooth.