RF-Aided Pre-Chamber Igniter for Lean Mixture Combustion
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Solution Overview
Problem
Conventional spark plugs struggle to ignite very lean air/fuel mixtures due to high breakdown voltage requirements, limiting emission reduction in engines and suffering from low component life, especially in larger combustion chambers without pre-combustion chambers.
Innovation Solution
An RF-aided pre-chamber igniter with a body and integral pre-combustion chamber, featuring at least one electrode that directs RF energy to lower ignition breakdown voltage and generates an arc to ignite the air/fuel mixture, using a combination of RF and DC power to create a corona and sustain combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional spark plug is used to ignite lean air/fuel mixtures, then the ignition breakdown voltage requirement becomes excessively high, but the component life decreases due to high voltage stress
Solution Approach 1:
The invention divides the single-point spark ignition into multi-point ignition by incorporating multiple electrodes (at least three) arranged in a triangular configuration within the pre-combustion chamber. This segmentation distributes the ignition stress across multiple points, reducing the breakdown voltage requirement at each electrode while extending component life through lower electrical stress on each individual electrode.
2Device complexity
If a single point arc from a conventional spark plug is used, then the device complexity remains low, but the ability to ignite very lean air/fuel mixtures is insufficient
Solution Approach 1:
The invention introduces a pre-combustion chamber as a preliminary ignition stage before the main combustion chamber. The lean air/fuel mixture is first ignited in this smaller pre-chamber using the multi-electrode spark plug, creating a pilot flame that then propagates into the main combustion chamber. This preliminary action in the pre-chamber makes it possible to successfully ignite very lean mixtures that would be difficult or impossible to ignite directly in the larger main combustion chamber.
3Temperature
If RF energy is used alone to ignite lean air/fuel mixtures, then the breakdown voltage requirement is reduced, but the energy is insufficient to sustain combustion
Solution Approach 1:
The invention combines two ignition mechanisms into a hybrid system: RF (radio frequency) energy and conventional electrical spark. The RF energy component (at frequencies such as 2.45 GHz) pre-heats and ionizes the lean air/fuel mixture, reducing the breakdown voltage requirement and facilitating easier ignition. The conventional electrical spark component then provides the additional energy needed to reliably ignite and sustain combustion. This merging of RF and spark technologies allows successful ignition of very lean mixtures while maintaining combustion stability.
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 igniter effectively reduces ignition breakdown voltage, improving combustion efficiency and extending component life by using a corona to facilitate ignition of lean air/fuel mixtures with lower energy requirements, applicable to various combustion engines.
Implementation Method 1
The at least one electrode is configured to direct RF energy to lower an ignition breakdown voltage requirement of an air and fuel mixture within the pre-combustion chamber
Implementation Method 2
The at least one electrode is configured to generate an arc that extends to an internal wall of the pre-combustion chamber and ignites the air and fuel mixture
Implementation Method 3
using a combination of RF and DC power to create a corona and sustain combustion
Data Source
AI summary
An igniter for an internal combustion engine is disclosed. The igniter may have a body, and a pre-combustion chamber integral with the body and having at least one orifice. The igniter may also have at least one electrode associated with the pre-combustion chamber. The at least one electrode may be configured to direct RF energy to lower an ignition breakdown voltage requirement of an air and fuel mixture in the pre-combustion chamber. The RF energy alone may be insufficient to ignite and sustain combustion of the air and fuel mixture. The at least one electrode may also be configured to generate an arc that extends to an internal wall of the pre-combustion chamber and ignites the air and fuel mixture.