Movable Piston Crown Pre-Chamber for Combustion Efficiency
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Solution Overview
Problem
Passive pre-chambers in engines are limited in efficiency across a wide range of operating conditions due to their size, ability to discharge residual gases, and the speed at which ignited gases ignite the main combustion mixture, necessitating an enhancement to improve performance.
Innovation Solution
A system with a pre-chamber positioned in the cylinder, featuring a piston crown with a pocket to direct squish flow into the pre-chamber, expelling residual gases and enhancing efficiency by aligning the pre-chamber and pocket along a central axis, and configuring the pre-chamber with openings to facilitate efficient gas flow and ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a passive pre-chamber is used to reduce cost and packaging space, then device complexity and cost are reduced, but combustion efficiency is limited to certain loads only
Solution Approach 1:
The patent introduces a movable piston crown that dynamically changes the pre-chamber volume during the engine cycle. The piston crown moves between a first position (expanding pre-chamber volume) and a second position (reducing pre-chamber volume), enabling the passive pre-chamber to adapt its characteristics throughout the operating cycle and improve combustion efficiency across a broader range of conditions.
Solution Approach 2:
The piston crown performs preliminary action by positioning itself in advance to control the pre-chamber volume before combustion occurs. By pre-adjusting the chamber volume during the compression stroke, the system optimizes combustion conditions before the actual combustion event takes place.
2Productivity
If the pre-chamber volume is increased to improve combustion efficiency, then ignition performance is enhanced, but packaging space requirement increases
Solution Approach 1:
The patent uses a movable piston crown to dynamically adjust the pre-chamber volume during the engine cycle. The piston crown transitions between a first position (increasing pre-chamber volume for better combustion) and a second position (reducing volume to save packaging space), allowing the system to achieve high combustion efficiency only when needed while minimizing space constraints.
Solution Approach 2:
The invention adds a temporal dimension to the pre-chamber volume by making it variable throughout the engine cycle. Instead of a fixed volume, the pre-chamber volume changes dynamically, allowing the system to achieve large effective volume during combustion while maintaining compact overall dimensions.
3Volume of stationary object
If the pre-chamber volume is reduced to save packaging space, then packaging space is optimized, but residual gas discharge ability deteriorates
Solution Approach 1:
The movable piston crown dynamically adjusts the pre-chamber volume to optimize residual gas discharge. During the compression stroke, the piston crown moves to its first position, maximizing the pre-chamber volume to facilitate effective residual gas discharge through the squish effect, then transitions to the second position to minimize volume for packaging efficiency.
Solution Approach 2:
The piston crown performs periodic motion between two positions during each engine cycle. This periodic action creates alternating phases of volume expansion (for residual gas discharge) and volume reduction (for packaging efficiency), ensuring that harmful residual gases are consistently removed while maintaining compact dimensions.
4Productivity
If ignition timing is advanced to improve combustion efficiency, then combustion completeness is enhanced, but risk of pre-ignition increases
Solution Approach 1:
The piston crown performs preliminary action by positioning itself in advance during the compression stroke to optimize the pre-chamber volume before ignition occurs. This pre-positioning allows for more flexible ignition timing control, enabling advanced ignition timing for complete combustion while the optimized chamber geometry prevents pre-ignition by ensuring proper charge preparation.
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 solution increases combustion efficiency across a broader range of operating conditions by effectively purging residual gases and promoting even ignition, thereby improving engine performance.
Implementation Method 1
the pocket may direct squish flow into the pre-chamber and expel residual gases therefrom
Data Source
AI summary
Methods and systems are provided for a pre-chamber. In one example, a system includes a pre-chamber and a piston arranged in a combustion chamber. The piston and/or combustion chamber comprise one or more features configured to force squish flow into the pre-chamber.