Pre-Chamber Ignition Gas Recirculation for Catalyst Temperature Control

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Solution Overview

Problem

During fuel shut-off conditions in internal combustion engines, the temperature of emission control devices like three-way catalysts can drop below efficient operating temperatures, leading to increased emissions and reduced fuel economy due to imbalanced oxidants and reductants, and the need for rich fueling to rebalance the catalyst.

Innovation Solution

A method involving a turbulent jet ignition system where pre-chamber injectors are opened during compression or expansion strokes to transfer hot, compressed gases between cylinders, maintaining the catalyst temperature above the light-off temperature and reducing the need for fuel enrichment by recirculating gases, thus preventing catalyst saturation with oxygen.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If fuel shut-off mode is used to reduce fuel consumption, then fuel economy is improved, but catalyst temperature decreases below light-off temperature and emissions increase

Engineering Contradiction:

Improvefuel consumptionVSAvoidcatalyst temperature

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

The pre-chamber injector serves as an intermediary component to transfer hot compressed gas from the pre-chamber to the main combustion chamber. This mediator mechanism allows heat transfer without requiring fuel combustion, enabling fuel shut-off mode to maintain catalyst temperature through gas recirculation rather than direct thermal contact or fuel enrichment

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the state parameters of the gas by compressing it in the pre-chamber to high pressure and temperature, then injecting it into the main chamber. This parameter transformation (compression heating) maintains exhaust temperature without fuel consumption, resolving the contradiction between fuel economy and catalyst temperature maintenance

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If fuel shut-off mode is used to reduce fuel consumption, then fuel economy is improved, but oxidant-reductant balance in catalyst is disturbed and nitrogen oxide emissions increase

Engineering Contradiction:

Improvefuel consumptionVSAvoidnitrogen oxide emissions

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The pre-chamber injector operates continuously during fuel shut-off mode to recirculate hot gas, maintaining continuous catalyst heating and oxidant-reductant balance. This continuous action prevents the disruption that would otherwise occur during fuel shut-off, allowing fuel economy improvement without nitrogen oxide emission increases

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system uses its own compressed gas (air or residual exhaust) as the recirculation medium, eliminating the need for external fuel or additional components. The pre-chamber compression process itself generates the hot gas needed for catalyst maintenance, making the system self-sufficient during fuel shut-off operation

Inventive Principle:

Principle #25Self-service

3Object-generated harmful factors

If rich fueling is used to restore oxidant-reductant balance in catalyst, then emissions are reduced, but fuel economy benefit from fuel shut-off mode is reduced

Engineering Contradiction:

ImproveemissionsVSAvoidfuel economy

Core Design Contradiction:

Object-generated harmful factorsVSUse of energy by moving object

Solution Approach 1:

The pre-chamber compression and hot gas recirculation occurs in advance during fuel shut-off mode, maintaining catalyst temperature and oxidant-reductant balance before combustion resumes. This preliminary action eliminates the need for subsequent rich fueling to restore catalyst state, preserving fuel economy benefits while preventing emissions

Inventive Principle:

Principle #10Preliminary action

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 maintains the catalyst temperature above the light-off temperature, reducing emissions and improving fuel economy by avoiding the need for rich fueling and minimizing oxygen saturation during fuel shut-off conditions.

Implementation Method 1

high pressure air and fuel are introduced into the pre-chamber via an injector of the TJI system, and when ignition is requested, the spark plug in the pre-chamber is actuated, igniting the air and fuel in the pre-chamber

Methodology Applied

Scientific EffectCompression heating: Adiabatic Heating

Implementation Method 2

Jets of flame and hot gas exit the pre-chamber and enter the cylinder via one or more small orifices in the pre-chamber walls

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS11352968B1Methods and systems for reducing catalyst cooling during fuel cut via pre-chamber ignition system

Publication Date: 2022.06.07 FORD GLOBAL TECH LLC

AI summary

Methods and systems are provided for transferring hot, compressed gases from one cylinder to another cylinder while fuel injection in both cylinders is deactivated. In one example, a method may include during a fuel shut-off event, opening a first pre-chamber injector of the first cylinder undergoing late compression or early expansion and opening a second pre-chamber injector of the second cylinder undergoing a late expansion and/or exhaust stroke or undergoing an intake stroke to allow a hot, compressed gas from the first cylinder to transfer to the second cylinder through the first and second pre-chamber injectors.