Gas Igniter Shroud Geometry for Faster Burner Ignition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gas igniter shrouds in home appliances suffer from delayed gas ignition due to convection heat pushing gas away from the igniter, leading to inefficiencies in oven temperature stability and safety concerns from unburned gas accumulation.
Innovation Solution
A redesigned igniter shroud with a convergent/divergent nozzle configuration that directs the gas/air mixture towards the heater element, enhancing rapid ignition by creating a fluid flow path that draws the mixture into a region of higher temperature for quicker ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional shroud with vented walls is used, then the igniter provides protection and allows heat to escape, but convection heat pushes gas away from the heater element causing delayed ignition
Solution Approach 1:
The patent inverts the conventional approach by using a solid wall shroud instead of vented walls. This reversal prevents convection currents from pushing gas away, and the solid structure actually helps direct heat and gas interaction more effectively for faster ignition.
Solution Approach 2:
The patent changes the physical parameters of the shroud from vented to solid wall construction. This parameter change fundamentally alters the flow dynamics, eliminating the harmful convection effect that caused gas to be pushed away from the heater element.
2Device complexity
If the heater element is located centrally within the shroud, then the structure is simple and symmetrical, but gas from the gas pipe is blown away into lower temperature regions causing lean gas/air mixture and delayed ignition
Solution Approach 1:
The patent introduces asymmetry in the shroud design with an off-center heater element position and an angled gas inlet. This asymmetric configuration creates a specific flow pattern that directs gas toward the heater element rather than allowing it to be blown away, improving ignition speed.
Solution Approach 2:
The patent applies local quality by creating a specific high-temperature zone at the gas inlet area through the angled inlet design. This localized modification ensures that gas enters a region optimized for rapid ignition without requiring complete redesign of the entire shroud structure.
3Temperature
If the shroud allows free convection flow, then heat can escape naturally, but this causes gas to be directed into lower temperature regions and disburse the gas/air mixture
Solution Approach 1:
The patent changes the thermal flow parameter from free convection to controlled flow through the solid wall design. This parameter change maintains necessary heat dissipation while preventing the gas mixture from being dispersed into lower temperature regions, thereby improving ignition reliability.
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 improved igniter achieves gas ignition within four seconds or less, improving oven temperature stability and safety by reducing the risk of unburned gas accumulation, and enhancing appliance efficiency.
Implementation Method 1
a user control or a thermostat switches power to an igniter and a gas valve circuit which are connected in series. As power flows through the igniter the current draw causes the igniter to produce heat. The igniter includes a resistive heater element
Implementation Method 2
As the heater element 110 is heated, convection heat is emitted... a fluid flow path through the chamber whereby a fluid stream is directed from the inlet opening, across the heater element, through the constriction to the outlet opening
Implementation Method 3
a constriction intermediate the inlet opening and the outlet opening, thereby defining a fluid flow path through the chamber whereby a fluid stream is directed from the inlet opening
Data Source
AI summary
A home appliance having an improved gas igniter (or ignitor) including an appliance body, at least one burner assembly supported in the appliance body to provide a heat source for cooking, with the burner assembly including a gas pipe, an igniter in operational communication with the gas pipe, the igniter including a heater element and a shroud covering a portion of the heater element, the shroud including a shroud body defining a chamber having the heater element therein, an inlet opening facing the gas pipe, an outlet opening facing away from the gas pipe, and a constriction intermediate the inlet opening and the outlet opening, thereby defining a fluid flow path through the chamber whereby a fluid stream is directed from the inlet opening, across the heater element, through the constriction to the outlet opening.