Crankshaft Position Detection for Engine Start-Up

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Solution Overview

Problem

In indirect injection internal combustion engines, determining the crankshaft position accurately and quickly is challenging when the engine is stopped, which hinders efficient start-up and can lead to increased pollution.

Innovation Solution

A method involving a sensor with a target linked to the crankshaft, detecting a reference index to identify the crankshaft position, allowing early fuel injection into selected cylinders before inlet valves close, ensuring accurate position knowledge and efficient combustion without pollution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If conventional methods are used to determine crankshaft position by rotating the crankshaft and reading sensor parameters, then the engine can eventually start, but the start-up time is extended and the engine cannot function satisfactorily without increased pollution

Engineering Contradiction:

Improvestart-up timeVSAvoidengine function satisfaction

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent applies preliminary action by injecting fuel into selected cylinders before the inlet valves close, based on pre-determined crankshaft position thresholds. This early fuel injection, combined with the improved position detection method, allows the engine to start more quickly and reliably without increasing pollution, as the fuel is already in position when combustion is initiated.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces conventional mechanical position detection methods with an improved sensor-based detection system that uses a reference index and threshold comparisons to determine crankshaft position. This substitution enables more accurate and faster position detection, directly reducing start-up time while maintaining reliable engine function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of time

If fuel is injected early into cylinders before inlet valves close, then crankshaft position knowledge is assured and start-up time is reduced, but fuel injection timing must be precisely controlled

Engineering Contradiction:

Improvestart-up timeVSAvoidinjection control complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent determines in advance which cylinders should receive fuel injection based on their crankshaft position characteristics. By pre-identifying the selected group of cylinders and their optimal injection timing windows, the system simplifies real-time control while achieving early fuel injection that reduces start-up time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by treating different cylinders differently - only the selected group of cylinders receives early fuel injection while others follow conventional timing. This localized approach optimizes start-up performance for specific cylinders without requiring complex coordination across all cylinders, thereby reducing overall control complexity.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If the reference index detection method is used to identify crankshaft position, then position detection accuracy is improved, but the system requires a sensor with target and reference index components

Engineering Contradiction:

Improvecrankshaft position detection accuracyVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical position sensing mechanisms with an optical or magnetic sensor system that detects a reference index on the crankshaft target. This substitution achieves high measurement precision through non-contact detection while actually reducing mechanical complexity compared to traditional mechanical sensors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The sensor system with target and reference index serves multiple functions: it detects crankshaft position, determines rotation direction, and provides timing reference for fuel injection and ignition. This multi-functionality achieves high measurement precision without requiring separate systems for each function, thereby reducing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7661412B2Method of controlling the start-up of an internal combustion engine

Publication Date: 2010.02.16 VITESCO TECH FRANCE

AI summary

A method of controlling the startup of an engine using a sensor having a reference index, commanding the rotation of the crankshaft, detecting the rotation of the crankshaft, selecting a group of cylinders for which the reference index is detected less than a half-turn of the crankshaft before the piston reaches the top dead center, before the inlet valves of the selected group of cylinders closes, commanding the injectors of the selected group of cylinders, detecting the reference index, and commanding the ignition element.