Fuel Injection Control for Pre-Ignition Prevention

Solution Overview

Problem

Internal combustion engines with high compression ratios and high EGR levels are prone to pre-ignition combustion events, which can cause damage due to high in-cylinder pressures, and existing methods for predicting and mitigating pre-ignition are not always effective, particularly as they may lead to increased HC, CO, and soot emissions.

Innovation Solution

A fuel injection control system that predicts in-cylinder temperature during compression and adjusts fuel injection timing and volume between the exhaust and intake strokes to prevent pre-ignition, using a fuel injector positioned upstream of the intake valve, with correction coefficients for various engine conditions to ensure accurate temperature prediction and reduced emissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fuel is injected during intake stroke to cool cylinder charge and reduce pre-ignition, then pre-ignition combustion events are reduced, but HC and CO emissions increase due to unburned fuel

Engineering Contradiction:

Improvepre-ignition preventionVSAvoidHC and CO emissions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The system performs preliminary cooling of the cylinder charge by injecting fuel during the intake stroke before compression occurs. This preliminary action reduces the peak temperature during compression, preventing pre-ignition while the fuel is subsequently burned in a controlled manner during the power stroke, minimizing unburned emissions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system dynamically adjusts fuel injection timing, injection amount, and injection duration based on detected engine operating conditions such as intake air temperature, engine load, and compression ratio. By changing these parameters adaptively, the system optimizes the balance between pre-ignition prevention and emission control.

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If fuel is injected during exhaust stroke to reduce HC, CO, and soot emissions, then emissions are reduced, but pre-ignition prevention is less effective

Engineering Contradiction:

ImproveHC, CO, and soot emissionsVSAvoidpre-ignition prevention

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The fuel injection process is segmented into multiple phases: an initial injection during the intake stroke for charge cooling and pre-ignition prevention, followed by additional injection during the exhaust stroke for emission control. This segmentation allows each injection event to serve its specific primary function while both contribute to overall engine efficiency.

Inventive Principle:

Principle #1Segmentation

3Power

If compression ratio is increased to improve engine power output, then power increases, but pre-ignition combustion events become more likely

Engineering Contradiction:

Improveengine power outputVSAvoidpre-ignition resistance

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The system performs preliminary cooling of the cylinder charge by injecting fuel during the intake stroke before compression occurs. This preliminary action reduces the peak temperature during compression, preventing pre-ignition while the fuel is subsequently burned in a controlled manner during the power stroke, minimizing unburned emissions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system dynamically adjusts fuel injection timing, injection amount, and injection duration based on detected engine operating conditions such as intake air temperature, engine load, and compression ratio. By changing these parameters adaptively, the system optimizes the balance between pre-ignition prevention and emission control.

Inventive Principle:

Principle #35Parameter changes

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 system effectively reduces pre-ignition events by injecting fuel during the intake stroke when high temperatures are predicted, minimizing unburned gas emissions and preventing engine damage, while also optimizing fuel injection to reduce HC, CO, and soot production.

Implementation Method 1

by injecting fuel into a cylinder of a PFI (Port Fuel Injection) type engine during intake stroke when an intake valve opens, the vaporization heat of fuel is utilized to achieve cylinder charge cooling

Methodology Applied

Scientific EffectVaporization heat: Evaporation

Implementation Method 2

The injection of fuel during exhaust stroke may reduce likelihood of the occurrence of HC, CO, soot and so forth because of the atomization of the injected fuel within an intake port before the injected fuel is combusted in a cylinder

Methodology Applied

Scientific EffectAtomization: Aerosol

Data Source

PatentUS9382856B2System for fuel injection control in an internal combustion engine

Publication Date: 2016.07.05 SUZUKI MOTOR CORP

AI summary

A system for fuel injection control in internal combustion engine is provided. Fuel is injected during exhaust stroke from a fuel injector for port injection upstream of an intake valve. In-cylinder temperature as the engine cylinder undergoes compression is predicted. Fuel is injected during intake stroke from the fuel injector to supply fuel to the inside of the cylinder upon determining that the predicated in-cylinder temperature is greater than a temperature beyond which pre-ignition is expected to happen.