Pre-Chamber Fueling Adjustment for Air-Fuel Ratio Control
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Solution Overview
Problem
In engines with pre-chamber ignition, gases flowing from the pre-chamber to the cylinder can disrupt the air-fuel ratio (AFR), leading to inaccurate fuel consumption and increased emissions, as residual gases from the pre-chamber can dilute or enrich the cylinder's air-fuel mixture.
Innovation Solution
Adjusting the fuel injection amount to the cylinder based on the amount and composition of pre-chamber gases during the compression stroke, using pressure differences and injection pressures to compensate for the effects of pre-chamber gases, thereby maintaining a desired AFR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If pre-chamber ignition is used to increase burn rate and power output, then engine power and efficiency are improved, but air-fuel ratio control accuracy deteriorates due to gas flow from pre-chamber to cylinder
Solution Approach 1:
The system uses oxygen sensors in the exhaust manifold to detect actual AFR conditions and feeds this information back to the controller. The controller then adjusts the cylinder fuel injector pulse width in real-time to compensate for AFR deviations caused by pre-chamber gas flow, maintaining accurate AFR control while utilizing pre-chamber ignition for improved power output.
Solution Approach 2:
The system dynamically changes the fuel injection amount (pulse width) based on detected AFR conditions. When pre-chamber gas flow causes leaner or richer conditions in the cylinder, the controller adjusts the cylinder fueling parameter to compensate, allowing the engine to maintain optimal AFR despite the disruptive gas flow from the pre-chamber.
2Productivity
If active purging is performed by injecting air into the pre-chamber to remove residual gases, then combustion efficiency is improved, but cylinder air-fuel ratio accuracy deteriorates due to uncontrolled gas flow into the cylinder
Solution Approach 1:
The oxygen sensors continuously monitor exhaust AFR and provide feedback to the controller about the net effect of pre-chamber gas flow on cylinder AFR. The controller uses this feedback to adjust cylinder fueling, compensating for the uncontrolled air flow from active purging and maintaining accurate AFR control throughout the operating range.
Solution Approach 2:
The system dynamically adjusts the cylinder fuel injection amount based on the detected AFR conditions resulting from active purging. When purging causes additional air to enter the cylinder and lean out the mixture, the controller increases fuel injection to compensate, maintaining the desired AFR while benefiting from improved combustion efficiency.
3Reliability
If residual gases from pre-chamber are allowed to flow to cylinder, then dilution effect may reduce knocking, but air-fuel ratio control deteriorates leading to increased emissions
Solution Approach 1:
The system adjusts the cylinder fuel injection amount based on detected AFR conditions caused by pre-chamber residual gas flow. When residual gases enrich or lean out the cylinder mixture, the controller compensates by changing the fuel injection parameter, maintaining optimal AFR for emissions control while allowing the beneficial dilution effect to reduce knocking.
Solution Approach 2:
Oxygen sensors provide continuous feedback on the actual AFR resulting from pre-chamber residual gas flow into the cylinder. The controller uses this feedback to make real-time adjustments to cylinder fueling, ensuring that emissions remain controlled even as residual gases naturally flow to dilute the charge and reduce knocking tendency.
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 enhances fuel efficiency and reduces emissions by accurately controlling the cylinder's air-fuel ratio, preventing non-stoichiometric operation and ensuring optimal engine performance.
Implementation Method 1
using pressure differences and injection pressures to compensate for the effects of pre-chamber gases
Implementation Method 2
When ignition is requested, 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
Data Source
AI summary
Methods and systems are provided for operating a cylinder of an engine including a pre-chamber ignition system. In one example, a method may include determining amounts of pre-chamber gases in the cylinder prior to combustion, and adjusting an amount of fuel injected into the cylinder based on the amounts of pre-chamber gases in the cylinder. In this way, cylinder fueling may be compensated for additional air and/or fuel from the pre-chamber gases, which may increase an accuracy of the cylinder fueling and increase cylinder efficiency.