Phonic Wheel Angular Position Detection Under Speed Variations

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Solution Overview

Problem

High-performance internal combustion engines with high compression ratios and light flywheels experience significant angular speed variations, leading to incorrect recognition of the singularity passage in existing phonic wheel position sensors, resulting in inaccurate determination of the drive shaft's angular position.

Innovation Solution

An electronic control unit analyzes tooth times using multiple equations to identify the singularity, ensuring accurate recognition by satisfying at least two and preferably three conditions, thereby enhancing the robustness of the identification process even under strong accelerations or decelerations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a simple tooth time comparison method is used to identify singularity passage, then the device complexity is low and ease of manufacture is high, but the reliability of singularity recognition deteriorates under high angular speed variations

Engineering Contradiction:

Improvesingularity recognition accuracyVSAvoididentification algorithm complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the parameters used for singularity identification from simple tooth time comparison to a multi-parameter analysis including current tooth time, previous tooth time, and following tooth time. This parameter expansion enables reliable singularity detection even under high angular speed variations, resolving the contradiction between reliability and complexity by using available temporal parameters in a more sophisticated comparison framework.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by comparing the current tooth time with both the previous tooth time and the following tooth time to confirm singularity passage. This feedback mechanism ensures that singularity identification is not based on a single measurement but on consistent temporal patterns, significantly improving reliability while maintaining computational feasibility through structured comparison logic.

Inventive Principle:

Principle #23Feedback

2Reliability

If the phonic wheel system is used to determine angular position, then the measurement capability is provided, but the reliability deteriorates when angular speed variations are very high

Engineering Contradiction:

Improveangular position determination accuracyVSAvoidangular speed variations

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of high angular speed variations into a beneficial identification criterion. By analyzing the temporal pattern of tooth times (current, previous, and following), the system identifies that singularity passage creates a distinctive temporal signature even under high speed variations. This approach transforms the previously harmful speed variations into a detectable pattern that confirms singularity passage, thereby improving reliability without requiring mechanical modifications.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If traditional singularity recognition methods are used, then the method simplicity is maintained, but the measurement precision deteriorates under strong accelerations or decelerations

Engineering Contradiction:

Improvesingularity passage detection accuracyVSAvoidalgorithm complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the tooth time analysis into three distinct temporal components: current tooth time, previous tooth time, and following tooth time. This segmentation allows the system to analyze the singularity passage event from multiple temporal perspectives, improving measurement precision by confirming the singularity through consistent patterns across all three segments rather than relying on a single measurement point.

Inventive Principle:

Principle #1Segmentation

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 method provides a reliable and fast recognition of the singularity passage without introducing delays, maintaining accuracy and simplicity, and can be implemented without adding new components, making it cost-effective and suitable for existing engines.

Implementation Method 1

a reader (e.g. of the inductive type having a varying reluctance or a Hall effect), which is arranged in a fixed position close to the phonic wheel and is adapted to read the passage of each tooth of the phonic wheel

Methodology Applied

Scientific EffectReluctance variation: Magnetic Reluctance

Implementation Method 2

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentEP2163856B1Method for determining the angular position of a drive shaft of an internal combustion engine

Publication Date: 2015.12.23 FAB ITAL MAGNETI MARELLI SPA

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AI summary

A method for determining the angular position of a drive shaft (4) of an internal combustion engine (1) provided with a phonic wheel (5), which is integral with the drive shaft (4), is provided with a plurality of equally spaced teeth (6), and has a singularity (S) consisting of at least one missing tooth (6) at a predetermined angular position; the method has the steps of: determining the passage of each tooth (6) of the phonic wheel (5) facing a reader (7) arranged in a fixed position; calculating in sequence each tooth time (T), i.e. the interval of time which elapses between the passage of a tooth (6) and the passage of the next tooth (6); and determining the passage of the singularity (S) according to the tooth times (T).