Pre-chamber Catalyst Heating via Exhaust Post-Injection
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Solution Overview
Problem
Internal combustion engines with pre-chamber ignition systems face inefficiencies in emissions control during cold start conditions, as emissions control devices like three-way catalysts or SCR devices do not operate efficiently until they reach a threshold temperature, leading to increased emissions before catalyst light-off.
Innovation Solution
A method is implemented where an additional amount of fuel is injected into the cylinder during the exhaust stroke based on the air-fuel ratios of the pre-chamber and cylinder mixtures, with pre-chamber combustion occurring during the compression and exhaust strokes to increase the emissions control device temperature, maintaining overall stoichiometry and generating heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If pre-chamber ignition is used to improve combustion efficiency and power output, then burn rate and power increase, but emissions control device temperature rises slowly during cold start
Solution Approach 1:
The system performs preliminary heating action by injecting fuel during the exhaust stroke before normal combustion begins, pre-heating the emissions control device to enable it to reach operational temperature faster during cold start conditions
Solution Approach 2:
The system applies periodic fuel injection pulses during the exhaust stroke at cold start conditions, creating repeated heating cycles that progressively raise the emissions control device temperature until it reaches light-off temperature
2Temperature
If additional fuel is injected during exhaust stroke to heat the catalyst, then emissions control device temperature increases, but maintaining stoichiometry becomes more complex
Solution Approach 1:
The system uses feedback from exhaust gas oxygen sensors to monitor air-fuel ratio and continuously adjusts the amount of post-injection fuel to maintain stoichiometric balance while heating the catalyst, creating a closed-loop control system
Solution Approach 2:
The system dynamically changes fuel injection parameters including timing, duration, and amount of post-injection fuel based on engine operating conditions and catalyst temperature requirements, allowing flexible control of the heating process
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 raises the temperature of the emissions control device, enhancing its efficiency and reducing engine emissions during cold start conditions by ensuring the device operates within optimal temperature ranges more quickly.
Implementation Method 1
When ignition is indicated, the spark plug in the pre-chamber actuates, igniting the first air-fuel mixture. As the first air-fuel mixture combusts, jets of flame and hot gas may exit the pre-chamber and enter the cylinder via one or more holes in the pre-chamber walls. These jets ignite the second air-fuel mixture in the cylinder air-fuel to produce torque.
Implementation Method 2
during a cold start condition, injecting an amount of post-injection fuel in a cylinder during an exhaust stroke of the cylinder, the amount based on an air-fuel ratio (AFR) of a first pre-chamber air-fuel mixture and an AFR of a first cylinder air-fuel mixture. In this way, a temperature of an emissions control device may be increased after a cold start, as post-injection fuel generates additional heat in the exhaust gas
Data Source
AI summary
Methods and systems are provided for operating a cylinder of an engine including a pre-chamber ignition system during a cold start condition. In one example, a method may include performing a post-injection in the cylinder, and then performing a pre-chamber combustion during an exhaust stroke of the cylinder. In this way, a temperature of a catalyst of the engine may be increased, which may decrease vehicle emissions during the cold start condition.