Camshaft Target Synchronization Without a Crankshaft Sensor

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Solution Overview

Problem

Existing synchronization methods for internal combustion engines are ineffective in the event of crankshaft sensor failure or significant acceleration, leading to unreliable engine phasing and increased synchronization time.

Innovation Solution

A method for determining the angular position of the camshaft target using a computing unit that acquires and processes signals from the camshaft sensor, computes theoretical and real ratios, and employs tolerance and confidence intervals to filter out unreliable edges, allowing for faster synchronization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing synchronization methods are used, then engine phasing can be determined under normal conditions, but the method becomes ineffective in the event of crankshaft sensor failure or significant acceleration

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidadaptability to sensor failure

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention extracts the synchronization function from the crankshaft sensor system and relocates it to the camshaft sensor system. By using only the camshaft target and sensor, the system removes the dependency on the crankshaft sensor, enabling synchronization to function independently when the crankshaft sensor fails or during conditions where it cannot provide reliable signals.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the operational parameters of the synchronization system by switching from crankshaft-based timing to camshaft-based timing. This parameter change allows the system to operate under different conditions (sensor failure, high acceleration) where the original crankshaft-based system would fail, thereby improving reliability and adaptability.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If traditional synchronization methods are used, then engine phasing can be determined, but synchronization time increases and phasing accuracy decreases under failure conditions

Engineering Contradiction:

Improvephasing accuracyVSAvoidsynchronization time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system continuously monitors the camshaft target signal in advance, maintaining readiness to perform synchronization at any moment. By having the camshaft-based measurement system already active and prepared, the system can immediately determine engine phasing without waiting for crankshaft sensor signals or performing extended synchronization routines, thereby reducing synchronization time while maintaining accuracy.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If the camshaft target has evenly distributed teeth, then the structure is simple, but correct phasing cannot be achieved without asymmetric tooth distribution

Engineering Contradiction:

Improvetarget manufacturing simplicityVSAvoidphasing precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention deliberately introduces asymmetry into the camshaft target by distributing teeth unevenly around the perimeter. This asymmetric pattern creates a unique signal signature that allows the system to determine the precise angular position of the camshaft and achieve correct engine phasing. The asymmetric design transforms a manufacturing complexity into a functional necessity for accurate synchronization.

Inventive Principle:

Principle #4Asymmetry

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 ensures reliable engine synchronization even in the absence of a crankshaft sensor, reducing synchronization time and improving phasing accuracy.

Implementation Method 1

The camshaft sensor interacts, in a manner known per se, with a disk-shaped camshaft target that is rigidly mounted on the camshaft. The rotation of the rotating target causes periodic modifications in the magnetic flux that are due to the passage of the markers

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

According to one example, the wheel is metal and the sensitive element, such as a Hall effect sensor, is able to detect metal

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS20260028944A1Method for synchronizing a combustion engine using a camshaft target

Publication Date: 2026.01.29 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

The invention relates to a method for determining the angular position of an unevenly toothed camshaft target. A sensor generates a signal upon each passage of the teeth, creating significant edges. A computing unit processes this signal in order to determine the time intervals between these edges, as well as to store theoretical ratios, tolerance intervals, and confidence intervals. Suspicion meters are associated with each edge. By computing real ratios based on the measured intervals, the unit discriminates the candidate edges: the edges that do not correspond to the tolerances are removed, those corresponding to the confidence intervals reset the suspicion meter, and those outside the confidence intervals increase the suspicion meter until they are removed. The steps are repeated until a single candidate edge is identified. The angular position of the target is then determined based on this single edge.