Spark Plug Layered Insulator High Frequency Ignition
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Solution Overview
Problem
Conventional ignition systems for gasoline engines face limitations in combustion stability and emissions at leaner homogeneous gasoline mixtures and high exhaust gas recirculation rates, particularly due to dielectric loss and voltage drop across air gaps in high frequency ignition systems, which can lead to malfunction and increased fuel consumption.
Innovation Solution
A spark plug design featuring a tubular insulator with a core and peripheral layer of different dielectric constants, where the peripheral layer has a higher dielectric constant than the core, reducing the electric field and potential for surface discharges, and eliminating the need for an inner rod-type electrode by forming the centre electrode as a hollow shaft on the insulator bore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional concentric arrangement of spark plug is used, then the structure is simple and easy to manufacture, but voltage drop across air gaps at electrode-insulator interfaces increases and causes malfunction
Solution Approach 1:
The invention extracts and eliminates the air gaps at the electrode-insulator interfaces by repositioning the electrodes away from the insulator surface. The counter electrode is positioned at the end of the insulator rather than surrounding it, and the center electrode is configured to minimize contact with the insulator, thereby removing the source of voltage drop and malfunction.
Solution Approach 2:
The invention transitions from a conventional concentric arrangement to a planar or offset configuration where electrodes are positioned in a different spatial dimension relative to the insulator. This dimensional change eliminates the radial air gaps that cause voltage drop, replacing them with controlled spark gaps at the firing tip.
2Volume of moving object
If high frequency operation is used, then the size of electronics and resonators is reduced, but dielectric loss increases and attenuates power source output
Solution Approach 1:
The invention extracts and removes the insulator material from the high electric field regions where dielectric loss would occur. By positioning electrodes away from the insulator surface and eliminating air gaps, the design removes the problematic dielectric interfaces that cause energy loss at high frequencies.
Solution Approach 2:
The invention changes the electrical parameters of the system by eliminating dielectric interfaces and air gaps. This results in reduced dielectric loss and improved power transfer efficiency at high frequencies, allowing the system to operate effectively at reduced sizes.
3Reliability
If glass is used to fill air gaps, then surface discharge is avoided, but shear stresses appear due to differential thermal expansion and dielectric constant may be too low
Solution Approach 1:
Instead of filling air gaps with glass, the invention extracts and eliminates the air gaps themselves by repositioning the electrodes. This removes the need for glass filling and avoids the associated problems of shear stresses from differential thermal expansion and insufficient dielectric constant.
4Object-generated harmful factors
If leaner homogeneous gasoline mixtures with high exhaust gas recirculation rates are used, then emissions and fuel consumption are reduced, but combustion stability deteriorates
Solution Approach 1:
The invention applies preliminary action by providing a more stable and longer duration spark through improved voltage delivery. The eliminated air gaps and reduced dielectric loss ensure that sufficient voltage reaches the spark gap reliably, initiating combustion more consistently in challenging lean mixtures with high EGR rates.
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
This design effectively reduces the risk of electrical breakdown and surface discharges, enhancing combustion stability and reducing emissions and fuel consumption by managing dielectric losses and voltage distribution within the spark plug.
Implementation Method 1
the tubular insulator member comprises a core made from a dielectric material exhibiting a first dielectric constant and an outer, peripheral layer made from a material exhibiting a greater dielectric constant than the insulator core that faces the shell portion of the counter electrode
Data Source
Figure 1a~2b
AI summary
A spark plug (10) for a high frequency ignition system comprises a centre electrode (24) having a front end with a firing tip (28); a tubular insulator member (20) having a front end (26) and an axial bore (22) accommodating the centre electrode (24), the electrode firing tip (28) protruding beyond the insulator front end. A counter electrode (16) comprises a shell portion (12) receiving said tubular insulator member (20). The tubular insulator member (20) comprises a core (30) made from a dielectric material exhibiting a first dielectric constant and a peripheral layer (32) in a material exhibiting a greater dielectric constant that faces the shell (12) portion of the counter electrode.