Ion Current Sensing for Combustion Phasing Estimation

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Solution Overview

Problem

Conventional internal combustion engines rely on expensive in-cylinder pressure transducers or complex artificial neural networks (ANNs) to estimate combustion phasing, which increases vehicle costs and processing requirements.

Innovation Solution

An ion sensing system generates an ion current signal across spark plug electrodes, with a controller monitoring peaks to estimate the location of peak pressure (LPP) and crankshaft angle (CA50) for precise combustion phasing control, eliminating the need for pressure transducers and ANNs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If in-cylinder pressure transducers are used to detect peak in-cylinder pressure for combustion control, then measurement precision is improved, but device complexity and vehicle cost increase

Engineering Contradiction:

Improvepeak in-cylinder pressure detectionVSAvoidsensor system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses ion current signal as an intermediary to indirectly detect peak in-cylinder pressure. Instead of directly measuring pressure with transducers, the system monitors ion current peaks generated during combustion, which correlate with pressure events. This intermediary approach enables pressure detection without requiring physical pressure sensors in the cylinder.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical pressure transducer system with an electrical ion current sensing system. By substituting the mechanical measurement approach (pressure transducers) with an electrical measurement approach (ion current through spark plug electrodes), the system achieves the same measurement function with reduced complexity and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If artificial neural networks are used to estimate combustion phasing, then measurement precision is improved, but processing complexity and computational requirements increase

Engineering Contradiction:

Improvecombustion phasing estimationVSAvoidprocessing system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex, computationally intensive artificial neural networks with simpler, more efficient signal processing algorithms. By using straightforward peak detection and correlation methods on ion current signals, the system achieves comparable estimation accuracy with significantly reduced processing complexity and computational resources.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If pressure transducers are installed in each cylinder for combustion control, then reliability of combustion phasing control is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecombustion phasing controlVSAvoidvehicle manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent makes the existing spark plug electrodes serve multiple functions: their primary function for ignition and a secondary function for sensing ion current during combustion. This multi-functionality eliminates the need for separate pressure sensing components, reducing manufacturing complexity and cost while maintaining combustion control reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the spark plug's own electrodes to generate the sensing signal (ion current) needed for combustion control. The spark plug serves itself by providing both the ignition function and the sensing function, eliminating the need for additional external sensors and simplifying the overall system architecture.

Inventive Principle:

Principle #25Self-service

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 approach reduces vehicle costs and processing complexity while providing accurate combustion phasing control and improved engine efficiency without additional sensors or complex neural networks.

Implementation Method 1

an ion sensing system configured to generate an ion current signal indicative of a measured current across electrodes of a spark plug

Methodology Applied

Scientific EffectIon current sensing: Ionisation

Data Source

PatentUS11187201B1Ion current sensing for estimation of combustion phasing in an internal combustion engine

Publication Date: 2021.11.30 FCA US LLC

AI summary

A combustion control system for an engine of a vehicle includes an ion sensing system configured to generate an ion current signal indicative of a measured current across electrodes of a spark plug associated with a cylinder of the engine and a controller configured to monitor for peaks in the ion current signal and, upon detecting at least a first peak and a second peak in the ion current signal, estimate a location of peak pressure (LPP) based on the detected second peak in the ion current signal, estimate an angle (CA50) of a crankshaft of the engine at which approximately 50% of the heat generated during combustion in the cylinder of the engine is released, and control combustion phasing of the engine based on the estimated CA50 angle.