Dual Air Injection for Catalyst Temperature Control

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Solution Overview

Problem

Existing engine systems face challenges in optimally converting hydrocarbon (HC), carbon monoxide (CO), and particulate matter (PM) emissions under non-stoichiometric conditions, particularly due to temperature limitations of catalysts in aftertreatment systems, which can lead to suboptimal performance and emissions exceeding regulatory standards.

Innovation Solution

The implementation of air injection systems before and/or after catalytic converters, with controlled air flow through upstream and downstream air injectors, to maintain catalysts within temperature limits and optimize conversion of HC, CO, and PM, using temperature sensors and a controller to manage air injection based on engine conditions and equivalence ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If air is injected into the exhaust system before the catalytic converter, then the conversion of HC, CO and PM is improved, but the catalyst temperature may exceed maximum temperature limits

Engineering Contradiction:

Improveconversion efficiencyVSAvoidcatalyst temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The air injection system is segmented into multiple injectors positioned at different locations (upstream and downstream of the catalytic converter) to distribute air injection across different zones, allowing conversion enhancement while controlling temperature rise through spatial distribution of the injection process

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Air is injected upstream of the catalytic converter before the exhaust gases enter the catalyst, allowing preliminary mixing and preparation of the exhaust stream to optimize conversion efficiency while controlling the temperature profile through advance air introduction

Inventive Principle:

Principle #10Preliminary action

2Temperature

If air is injected after the catalytic converter, then catalyst temperature is controlled below maximum limits, but conversion of HC, CO and PM may be suboptimal

Engineering Contradiction:

Improvecatalyst temperatureVSAvoidconversion efficiency

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The air injection function is extracted and placed downstream of the catalytic converter in addition to upstream injection, allowing the catalyst to operate at controlled temperatures while still achieving high conversion efficiency through post-catalyst air introduction and oxidation chamber processing

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

An oxidation chamber with a mixing plate is introduced as an intermediary component downstream of the catalytic converter to facilitate further conversion of HC, CO and PM through controlled air mixing and oxidation, enhancing overall conversion efficiency while maintaining catalyst temperature control

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the first orifice has a smaller flow area, then mixing and accuracy of upstream air injection is improved, but the system complexity increases

Engineering Contradiction:

Improveair injection accuracyVSAvoidorifice configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Different orifice flow areas are assigned to different injection locations (smaller orifice upstream, larger orifice downstream) to optimize the specific function of each injector, with the smaller upstream orifice providing precise mixing and accurate air dosage where needed most

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 tailpipe emissions of HC and CO, and PM while protecting catalyst components from excessive temperatures, ensuring optimal conversion across a wide range of engine operating conditions without exceeding catalyst temperature limits.

Implementation Method 1

an oxidation chamber. A mixing plate is disposed in the oxidation chamber and is configured to allow the exhaust gas stream to pass through the oxidation chamber

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

A catalytic converter is included in the exhaust system and is configured with upstream and downstream air injections

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 3

A first temperature sensor is disposed in the exhaust system upstream from the catalytic converter and a second temperature sensor disposed in the exhaust system downstream from the catalytic converter

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentUS11629625B1Systems and methods of engine exhaust air injection before and after catalytic converters

Publication Date: 2023.04.18 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Engine systems and methods use a dual air injection approach to control exhaust reactions and to maintain temperatures below a maximum limit of exhaust system components during engine enrichment operation conditions. Dual air injectors are disposed in the exhaust system with one upstream from, and another downstream from, the catalytic converter. Providing air injection before and/or after the converter helps convert all HC, CO, and PM emissions while keeping the catalyst temperature below the catalyst protection temperature limit. Air injection quantity may be controlled and diagnosed by monitoring the temperatures before and after the catalytic converter. The catalytic converter may be a three-way catalytic converter for lower cost or a downstream two-way catalytic converter may be added if further emission reduction is necessary.