Pre-Chamber Ignition Timing During Catalyst Heating
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Solution Overview
Problem
Pre-chamber ignition systems face challenges in achieving stable late ignition timings during catalyst heating, leading to increased misfires due to dissipated turbulence and fast burn rates, which also result in higher hydrocarbon emissions and increased costs from additional spark plugs and complex control systems.
Innovation Solution
Injecting fuel and air into the pre-chamber during the expansion stroke, after the compression stroke, to effectively purge residual gases and maintain turbulence, allowing for reliable ignition timing adjustments based on catalyst temperature and torque output, thereby reducing emissions and system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If pre-chamber ignition is used to achieve fast burn rate and increased power, then power output is improved, but turbulence dissipates by late ignition timing causing misfire
Solution Approach 1:
The system dynamically switches between pre-chamber ignition and direct spark ignition based on operating conditions. During catalyst heating when late ignition timing is required, direct spark ignition is used to maintain stability. During normal operation, pre-chamber ignition provides fast burn rate and high power. This dynamic adaptation resolves the contradiction between power output and ignition stability.
Solution Approach 2:
The ignition system changes the ignition method parameter based on the required spark timing. When catalyst heating is detected and late timing is needed, the system transitions from pre-chamber ignition to direct spark ignition. This parameter change allows the system to maintain reliable ignition under late timing conditions while preserving the high power capability of pre-chamber ignition during appropriate operating conditions.
2Reliability
If additional spark plug is added to provide ignition during catalyst heating, then ignition reliability is improved, but system cost and complexity increase
Solution Approach 1:
The pre-chamber serves multiple functions: it provides fast burn rate during normal operation for high power output, and it can be purged and reused during catalyst heating conditions to support late ignition timing. This multi-functionality eliminates the need for separate ignition components, maintaining reliability without increasing system complexity.
Solution Approach 2:
During catalyst heating, the pre-chamber is temporarily discarded from the ignition process and instead used for storing fresh charge. The pre-chamber is purged of residual gases and refilled with fresh air-fuel mixture, then this stored charge is utilized for ignition during late timing operations. This recovering approach allows the same component to serve different functions based on operating conditions, avoiding additional complexity.
3Loss of time
If pre-chamber is used during catalyst heating, then ignition timing can be delayed, but hydrocarbon emissions increase due to large crevice volume
Solution Approach 1:
The harmful residual gases that would otherwise remain trapped in the pre-chamber crevice volume are extracted and purged into the main combustion chamber during the transition to direct spark ignition mode. This extraction of residuals before the large crevice volume issue occurs during catalyst heating reduces hydrocarbon emissions while allowing the necessary ignition timing delay.
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 method enables robust and efficient pre-chamber ignition during catalyst heating, reducing emissions and costs by eliminating the need for additional spark plugs and optimizing ignition timing for improved combustion stability and fuel efficiency.
Implementation Method 1
turbulence in the pre-chamber is largely generated from combustion chamber gases being forced into the pre-chamber through the small orifices during the compression stroke of the cylinder
Implementation Method 2
the spark plug in the pre-chamber is actuated, igniting an air-fuel mixture in the pre-chamber
Implementation Method 3
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
Data Source
AI summary
Methods and systems are provided for operating a pre-chamber to provide ignition to a cylinder during catalyst heating. In one example, a method may include injecting fuel and air into a pre-chamber of an engine cylinder during an expansion stroke of the engine cylinder responsive to a temperature of a catalyst being less than a threshold temperature, and injecting the fuel and the air into the pre-chamber during a compression stroke of the engine cylinder responsive to the temperature of the catalyst being greater than or equal to the threshold temperature. In this way, the pre-chamber may provide robust ignition to the cylinder during a variety of operating conditions.