Adjustable Pre-Chamber Volume Ratio for Engine Ignition
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Solution Overview
Problem
Passive pre-chambers without a series gap igniter often fail to provide reliable ignition across a wide range of engine operating conditions, leading to increased costs and reduced engine performance due to hot spots caused by electrode heating, which can decrease power output and combustion stability.
Innovation Solution
An engine system with a pre-chamber that includes a moveable element to adjust the ratio of dead volume to internal volume, allowing for enhanced combustion conditions across various engine conditions without a second spark plug, thereby improving reliability and longevity of the ignition device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a passive pre-chamber without a series gap igniter is used, then the packaging size is reduced and cost is decreased, but reliable ignition cannot be provided over the full range of engine operating conditions
Solution Approach 1:
The patent applies the Dynamics principle by making the pre-chamber volume adjustable through a moveable element that can change the dead volume. This allows the pre-chamber to dynamically adapt its volume ratio in response to varying engine operating conditions, ensuring reliable ignition across the full operating range while maintaining a simpler structure than a fixed series gap igniter
2Reliability
If a series gap igniter is used, then reliable ignition is provided over a wide range of conditions, but electrode heating causes hot spots that decrease power output and combustion stability
Solution Approach 1:
The patent applies the Parameter changes principle by changing the dead volume to internal volume ratio parameter in response to engine operating conditions. By adjusting this volume ratio, the system optimizes combustion conditions and reduces electrode heating that leads to hot spots, while maintaining reliable ignition across different operating conditions
3Reliability
If a series gap igniter is used, then reliable ignition is achieved, but the packaging size of the pre-chamber is increased
Solution Approach 1:
The patent uses a moveable element that can shift positions to adjust the dead volume, allowing the pre-chamber to achieve reliable ignition with a compact packaging size. The dynamic adjustment of volume ratio eliminates the need for a larger series gap igniter structure while maintaining ignition reliability
4Device complexity
If the pre-chamber volume is not adjusted, then the structure is simple, but combustion conditions cannot be optimized across various engine conditions
Solution Approach 1:
The patent applies parameter changes by adjusting the dead volume to internal volume ratio in response to engine operating conditions such as intake valve closing timing. This optimization of combustion conditions across various engine conditions is achieved through a relatively simple moveable element mechanism
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 system ensures reliable ignition and increased fuel economy by adjusting the pre-chamber volume ratio in response to intake valve closing timing, reducing the likelihood of hot spots and extending the life of the ignition device.
Implementation Method 1
A moveable element is positioned in the internal volume and fluidly coupled to the dead volume, wherein moving the moveable element changes a ratio of the dead volume to the internal volume
Implementation Method 2
When ignition is requested, 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. These jets ignite the air-fuel mixture in the cylinder to produce torque
Implementation Method 4
During engine operation, an air-fuel mixture is introduced into the cylinder, and 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
Data Source
AI summary
Methods and systems are provided for an engine, including an engine cylinder coupled to a cylinder head, and a pre-chamber. The pre-chamber includes a first end proximal to the cylinder head, a spark gap, and pre-chamber walls enclosing an internal volume including a dead volume. The dead volume includes all of the internal volume positioned between the first end and the spark gap. A moveable element is positioned in the internal volume and fluidly coupled to the dead volume, wherein moving the moveable element changes a ratio of the dead volume to the internal volume. In this way, combustion conditions may be enhanced at a plurality of engine conditions.