Variable Volume Pre-Chamber Igniter for Combustion Stability
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Solution Overview
Problem
Passive pre-chamber ignition systems lack direct control over fuel and oxygen levels, leading to decreased combustion stability and increased misfire incidents, especially during low load and cold start conditions, and active pre-chamber systems increase system complexity and cost due to additional injectors.
Innovation Solution
A pre-chamber igniter with an adjustable cap that varies the internal volume and spark gap to optimize ignition across a range of operating conditions, using an actuator to move the cap between retracted and extended positions, thereby adjusting the pre-chamber volume and spark gap to enhance combustion stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive pre-chamber ignition is used, then the system structure is simple, but combustion stability decreases and misfire incidence increases during low load and cold start conditions
Solution Approach 1:
The pre-chamber volume is made variable through a movable cap that can adjust between retracted and extended positions. This dynamic volume adjustment allows the system to adapt to different operating conditions, improving combustion stability during low load and cold start conditions while maintaining structural simplicity compared to active injection systems
Solution Approach 2:
The system changes the physical parameter of pre-chamber volume to optimize combustion characteristics. By varying the pre-chamber volume, the system can control the amount of air-fuel mixture inducted into the pre-chamber, thereby maintaining reliable ignition across different operating conditions without adding complex injection hardware
2Reliability
If active pre-chamber system with direct fuel and oxygen injection is used, then combustion stability improves, but system complexity and cost increase due to additional injectors
Solution Approach 1:
The invention extracts the volume adjustment function from complex injection systems and implements it through a simpler movable cap mechanism. This removes the need for pre-chamber fuel injectors and air injectors, thereby reducing system complexity and cost while maintaining the ability to control pre-chamber conditions for stable combustion
Solution Approach 2:
The movable cap system allows the pre-chamber to self-regulate its volume and air-fuel mixture induction based on operating conditions, eliminating the need for active injection systems. The system serves itself by using pressure differentials during compression stroke to induce the appropriate amount of air-fuel mixture into the pre-chamber
3Reliability
If pre-chamber volume is increased, then combustion stability improves during low load operation, but ignition speed decreases
Solution Approach 1:
The movable cap enables dynamic adjustment of pre-chamber volume, allowing the system to have a larger volume during low load operation for stability, and a smaller volume during high load operation for faster ignition speed. This dynamic adaptability resolves the trade-off between combustion stability and ignition speed
4Volume of stationary object
If cap is extended toward piston, then pre-chamber volume increases for better low load combustion, but space for other components is reduced
Solution Approach 1:
The movable cap provides a space-efficient solution by dynamically adjusting pre-chamber volume rather than requiring a permanently large pre-chamber. When extended, it increases volume for low load stability; when retracted, it maximizes space for other components, thereby resolving the packaging constraints
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
The adjustable pre-chamber system provides robust ignition across a wider range of conditions, reducing misfires and increasing engine efficiency while maintaining a lower cost and complexity compared to active pre-chamber systems, allowing for larger intake and exhaust valves and higher engine power capacity.
Implementation Method 1
the spark plug in the pre-chamber is actuated, igniting the fraction of the air-fuel mixture in the pre-chamber
Implementation Method 2
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
Implementation Method 3
the cap may be adjusted between the first position and the second position to vary the internal volume of the pre-chamber
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 system may include a pre-chamber igniter coupled to a cylinder of an engine, the pre-chamber igniter including a movable cap enclosing an internal volume of the pre-chamber igniter and separating the internal volume of the pre-chamber igniter from an internal volume of the cylinder. By adjusting a position of the cap, the internal volume of the pre-chamber igniter may be adjusted to provide reliable ignition to the cylinder across a wide range of operating conditions.