Engine Load Management for Cold Start Particulate Reduction

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Solution Overview

Problem

Direct-injection engines emit increased particulate matter during cold starts due to inadequate fuel vaporization and excess fuel injection, exacerbated by higher engine loads which increase manifold air pressure, reducing atomization and vaporization efficiency.

Innovation Solution

Implementing a method that delays transmission up-shift during warm-up periods following a cold start, reduces air-charge pressure in cylinders, and adjusts intake valve schedules to enhance fuel atomization and vaporization, thereby reducing particulate emissions by operating at lower manifold pressures and higher speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If excess fuel injection is used during cold start to achieve stable combustion, then combustion stability is improved, but particulate emissions increase

Engineering Contradiction:

Improvecombustion stabilityVSAvoidparticulate emissions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the air-to-fuel ratio parameter during cold start by reducing excess fuel injection. The system maintains a controlled rich mixture (lambda < 1.0) rather than excessive rich mixture, optimizing the balance between combustion stability and particulate emission reduction through precise fuel quantity control

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamic adjustment of fuel injection strategy based on real-time engine operating conditions during cold start. The control system continuously monitors parameters such as coolant temperature, intake air temperature, and engine load to dynamically optimize the air-to-fuel ratio, transitioning from excessive fuel injection to controlled fuel injection as the engine warms up

Inventive Principle:

Principle #15Dynamics

2Power

If higher engine load is applied during cold start to meet driver demand, then acceleration performance is improved, but fuel atomization and vaporization deteriorate

Engineering Contradiction:

Improveacceleration performanceVSAvoidfuel atomization quality

Core Design Contradiction:

PowerVSManufacturing precision

Solution Approach 1:

The patent changes the manifold air pressure parameter during cold start by controlling the throttle position and intake valve timing to maintain lower MAP levels. This parameter change ensures better fuel atomization and vaporization by reducing the counter-pressure that opposes fuel injection, while still meeting acceleration demands through optimized ignition timing and air intake control

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary heating to the fuel injection system and intake air before cold start operation. The system pre-heats the fuel to improve its atomization characteristics and pre-warms the intake air to enhance vaporization, thereby preparing the system for better fuel-air mixing even under higher load conditions during cold start

Inventive Principle:

Principle #10Preliminary action

3Object-generated harmful factors

If manifold air pressure is reduced during cold start to improve fuel atomization, then particulate emissions decrease, but engine power output is reduced

Engineering Contradiction:

Improveparticulate emissionsVSAvoidengine power output

Core Design Contradiction:

Object-generated harmful factorsVSPower

Solution Approach 1:

The patent implements dynamic throttle control that adjusts manifold air pressure in real-time based on driver demand and engine temperature. During cold start, the system maintains lower MAP to improve atomization, but can quickly increase MAP when acceleration is demanded, providing dynamic balance between emission control and power delivery

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies different air-to-fuel ratio strategies to different cylinders or different phases of the engine cycle. By optimizing local combustion conditions in the intake manifold and combustion chambers, the system achieves good atomization and vaporization locally while maintaining overall engine power output through coordinated control of multiple parameters

Inventive Principle:

Principle #3Local quality

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 effectively reduces particulate emissions by improving fuel atomization and vaporization during cold starts without significant loss of acceleration potential, maintaining efficient engine operation and emissions control.

Implementation Method 1

inadequately vaporized, requiring excess fuel injection to achieve stable combustion. The excess fuel may result in an over-rich air-to-fuel ratio, which causes increased PM emission. This issue may be exacerbated when the engine is significantly loaded during the cold start, as higher engine load results in increased manifold air pressure (MAP), which may reduce the degree of atomization and vaporization of the injected fuel.

Methodology Applied

Scientific EffectAtomization:

Implementation Method 2

Methodology Applied

Scientific EffectVaporization: Evaporation

Data Source

PatentUS9169791B2Engine-load management to reduce particulate emissions

Publication Date: 2015.10.27 FORD GLOBAL TECH LLC

AI summary

A method for operating an engine of a vehicle. During a warm-up period following a cold start of the vehicle, a cylinder of the engine is charged to a reduced air-charge pressure, and fuel is injected into the cylinder. After the warm-up period, the cylinder is charged to a non-reduced air-charge pressure, greater for an equivalent driver demand than the reduced air-charge pressure, and fuel is injected into the cylinder.