Multi-layer Ceramic Igniter with Converging Facets for Rapid Gas Mixture Ignition
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Solution Overview
Problem
Existing multi-layer ceramic heaters and igniters face challenges in achieving rapid response time and durability while maintaining competitive manufacturing costs, particularly in applications requiring quick start-up and prolonged high-temperature operation.
Innovation Solution
A rod-shaped ceramic heater/igniter design featuring a central resistive core with annular segments and slightly converging facets, where the annular segments are connected to positive and negative electrical potentials, and an insulative layer is used between the core and outer resistive layers, allowing for unique electrical properties and potentially eliminating the need for a conductive core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional single-layer ceramic heater design is used, then the manufacturing process is simple, but the response time from room temperature to ignition temperature is slow
Solution Approach 1:
The heater is divided into multiple functional layers with distinct purposes: a PTC resistive layer for rapid self-regulating heating, a conductive layer for efficient electrical connection, and an insulative layer for thermal management. This segmentation allows each layer to optimize its specific function, resulting in faster overall response time while maintaining manufacturability through standard ceramic layering techniques
Solution Approach 2:
The heater employs a composite structure combining different ceramic materials with complementary properties: PTC ceramic for positive temperature coefficient heating, conductive ceramic for electrical pathways, and insulative ceramic for thermal isolation. This composite approach enables rapid temperature rise and precise thermal control without requiring complex single-material solutions
2Duration of action of stationary object
If the heater operates at high temperatures for extended periods, then the ignition function is effective, but the durability and reliability decrease
Solution Approach 1:
The insulative layer is positioned between the resistive heating elements and the substrate to provide thermal cushioning before excessive heat can damage the structural support. This pre-positioned thermal barrier protects the heater structure from thermal degradation during extended high-temperature operation, maintaining reliability over prolonged duration
Solution Approach 2:
The PTC material exhibits a positive temperature coefficient where its electrical resistance increases with temperature. This automatic parameter change allows the heater to self-regulate: as temperature rises to the ignition point, resistance increases, reducing current and preventing overheating. This self-regulating mechanism enables sustained operation at high temperatures without degradation
3Ease of manufacture
If a multi-layer structure with insulative and conductive layers is implemented, then the electrical properties and heating efficiency improve, but the manufacturing complexity increases
Solution Approach 1:
Each ceramic layer serves multiple functions simultaneously: the resistive layer provides both heating and structural integrity, the conductive layer provides both electrical connection and mechanical support, and the insulative layer provides both thermal isolation and layer separation. This multi-functionality reduces the need for additional specialized components, simplifying the overall manufacturing process despite the multi-layer structure
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 design achieves faster response times and enhanced durability, enabling the heater/igniter to efficiently ignite gas mixtures and operate for extended periods without replacement, while maintaining cost-effectiveness.
Implementation Method 1
The resistive layer has a positive temperature coefficient (PTC) of electrical resistance
Implementation Method 2
an insulative layer disposed over the electrode, a resistive layer disposed over the insulative layer
Implementation Method 3
a portion of the heater extends into the combustion chamber to transfer heat to the fuel-air mixtures
Implementation Method 4
transfer heat to the fuel-air mixtures contained in the cylinder
Data Source
AI summary
A multi-layer rod shaped ceramic igniter includes an elongated tapered electrode having a central core of resistant material and two annular segments. One of the segments in on one side of the core and the other on an opposite side and connected to two slightly converging facets extending along the core. The multi-layered rod shaped ceramic igniters disclosed herein may be manufactured by slip-casting, injection molding or extruding a green annular body and removing material from opposite sides of the green body to form two almost parallel but slightly converging facets that extend over the heater igniter between the back surface and the tip of the igniter. After removing material between the annular segments the igniter is air dried and then heated in a vacuum at atmospheric pressure to approximately 900° C. in order to burn off the organic binder. The ceramic is then held in an inert atmosphere and heated to a temperature of 1600° C. and under an isotatic pressure of greater than 10 mega pascales for sintering the layer into a unitary monolithic structure.