Variable Volume Pre-Chamber Igniter for Combustion Stability
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Solution Overview
Problem
Passive pre-chamber ignition systems in internal combustion engines lack direct control over fuel and oxygen levels, leading to decreased combustion stability and increased misfire incidents, especially at low load and cold start conditions, and active pre-chamber systems with additional injectors increase complexity and cost.
Innovation Solution
A variable volume pre-chamber igniter with an adjustable cap that changes internal volume based on engine load, speed, and temperature, allowing for robust ignition across a range of operating conditions without the need for additional fuel injectors, by increasing volume at low loads and decreasing volume at high loads and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive pre-chamber ignition is used, then the system is simple and cost-effective, but combustion stability decreases and misfire incidence increases at low load and cold start conditions
Solution Approach 1:
The pre-chamber volume is made variable through a movable cap that can adjust its position along the central axis of the pre-chamber. This dynamic volume adjustment allows the system to adapt to different operating conditions (load, speed, temperature) without adding complex injection systems, thereby maintaining combustion stability while avoiding the complexity of active pre-chamber systems with multiple injectors.
2Reliability
If active pre-chamber system with direct fuel and oxygen injection is used, then combustion stability improves, but device complexity and cost increase
Solution Approach 1:
The invention extracts only the essential function needed for combustion stability (volume control) while removing the complex fuel and oxygen injection systems. By using a movable cap to adjust pre-chamber volume, the system achieves combustion stability without the need for pre-chamber fuel injectors and air injectors, thereby reducing device complexity and cost.
Solution Approach 2:
The movable cap serves multiple functions: it adjusts pre-chamber volume, controls the spark gap distance, and regulates the amount of air-fuel mixture inducted into the pre-chamber. This multi-functionality replaces the need for separate fuel and air injection systems, achieving combustion stability while maintaining system simplicity.
3Reliability
If pre-chamber volume is increased, then combustion stability improves at low load, but system size and packaging constraints worsen
Solution Approach 1:
The pre-chamber volume is made variable through a movable cap that can adjust its position. This allows the system to increase volume when combustion stability is needed (low load, cold start) and decrease volume when packaging space is constrained or when operating at high load, providing adaptability without permanent increase in system size.
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 combustion stability and engine efficiency by providing reliable ignition at low engine loads and temperatures while reducing the complexity and cost of the pre-chamber system, allowing for larger intake and exhaust valves and increased engine power capacity.
Implementation Method 1
a fraction of the air-fuel mixture is inducted into the passive pre-chamber via a pressure differential between the passive pre-chamber and the cylinder during a compression stroke of the cylinder
Implementation Method 2
the spark plug in the pre-chamber is actuated, igniting the fraction of the air-fuel mixture in the pre-chamber
Implementation Method 3
After the fraction of the air-fuel mixture is ignited in the pre-chamber, 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
Data Source
AI summary
Systems and methods are provided for a variable volume pre-chamber igniter, which may be coupled in an engine system. In one example, a method may include adjusting an internal volume of a pre-chamber igniter based on operating conditions by adjusting a position of a cap of the pre-chamber igniter, the pre-chamber igniter including a plurality of orifices fluidically coupling the pre-chamber igniter to a main combustion chamber of a cylinder of an engine. By adjusting a position of the cap, the internal volume of the pre-chamber igniter may be increased or decreased to provide reliable ignition to the cylinder across a wide range of operating conditions.