Spark Plug Head Protrusion for Ignition Stagnation
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Solution Overview
Problem
Existing ignition devices for internal combustion engines face challenges in enhancing ignitability of the air-fuel mixture without increasing ignition energy, as high-speed mixture flow disrupts flame growth and increasing energy leads to mechanical wear of spark plug electrodes.
Innovation Solution
An ignition device with a spark plug having a housing with a protruding head downstream of the spark gap, creating a stagnating region where mixture flow is slowed, allowing sequential ignitions to combine and enhance flame growth without increasing ignition energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple ignition events are produced to enhance ignitability, then flame growth is disturbed by high-speed mixture flow, but increasing ignition energy accelerates mechanical wear of electrodes
Solution Approach 1:
The protruding head of the housing acts as an intermediary structure that modifies the mixture flow pattern. It creates a stagnating region that serves as a mediator between the spark gap and the high-speed flow, allowing flames to develop without being immediately swept away, thereby reducing the need for excessive ignition energy
Solution Approach 2:
The housing head is designed with a specific protruding shape that creates localized flow characteristics. The stagnating region formed at the downstream side of the protruding head provides a local area with reduced flow velocity, enabling controlled flame development in that specific zone while maintaining normal flow elsewhere
2Reliability
If ignition energy is increased to improve ignitability, then flame growth is enhanced, but service life of spark plug decreases due to electrode wear
Solution Approach 1:
The protruding head structure serves as a flow mediator that creates favorable conditions for flame development without requiring increased energy input. By modifying the local flow field to produce a stagnating region, it enables efficient combustion at lower ignition energies, thereby reducing electrode wear and extending service life
Solution Approach 2:
The invention changes the flow velocity parameter in the region downstream of the spark gap by introducing the protruding head structure. This creates a localized parameter change (reduced velocity) that allows flames to remain in the combustion chamber longer and combine effectively, achieving good ignitability without increasing ignition energy
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 device improves ignitability of the mixture by allowing flames to collide and combine in the stagnating region, enhancing combustion without the need for increased ignition energy, thus prolonging spark plug service life and reducing mechanical wear.
Implementation Method 1
The protruding head of the housing has at least a portion located downstream of the spark gap in a mixture flow within the combustion chamber. A stagnating region is formed which is located adjacent and downstream of the protruding portion and where the mixture flow has a lower flow velocity.
Data Source
AI summary
An ignition device for an internal combustion engine is provided which includes a spark plug and a controller. The spark plug has a housing with a head protruding into a combustion chamber of the engine. The head has at least a portion located downstream of a spark gap of the spark plug in an air-fuel mixture flow within the combustion chamber. The controller works to perform a plurality of discharge events in the spark plug in each cycle of an operation of the engine. This improves the ability of the spark plug to ignite the mixture without need to increase an ignition energy.