Ignition device for a gas appliance and method of operation

Abstract

An ignition device for a gas appliance is provided. The ignition device includes a membrane and a plurality of heating elements embedded in the membrane, wherein the heating elements comprise a plurality of patterned resistors and wherein the plurality of heating elements are configured to heat a surface on application of voltage through the heating elements. The ignition device also includes a cavity disposed adjacent to the heating elements and configured to provide thermal isolation of the heating elements.

1 . An ignition device for a gas appliance, comprising: 
 a membrane;    a plurality of heating elements embedded in the membrane, wherein the heating elements comprise a plurality of patterned resistors and wherein the plurality of heating elements are configured to heat a surface on application of voltage to the heating elements; and    a cavity disposed adjacent to the heating elements and configured to provide thermal isolation of the heating elements.    
   
   
       2 . The ignition device of  claim 1 , wherein the membrane comprises a non-electrically conductive material.  
   
   
       3 . The ignition device of  claim 2 , wherein the membrane comprises un-doped silicon carbide, or silicon nitride, or boron nitride.  
   
   
       4 . The ignition device of  claim 1 , wherein the heating elements comprise an electrically conductive material.  
   
   
       5 . The ignition device of  claim 4 , wherein the heating elements comprise doped silicon carbide.  
   
   
       6 . The ignition device of  claim 1 , wherein the cavity is sealed in vacuum, or in an inert environment to substantially prevent degradation of the heating elements.  
   
   
       7 . The ignition device of  claim 1 , wherein the membrane comprises contact pads configured to provide electrical connection for the ignition device.  
   
   
       8 . The ignition device of  claim 7 , wherein the contact pads comprise doped silicon carbide, or doped silicon carbide coated with nickel, or gold, or platinum, or tungsten, or combinations thereof.  
   
   
       9 . The ignition device of  claim 1 , wherein the ignition device is configured to sense a temperature based upon a measured resistivity of the heating elements.  
   
   
       10 . The ignition device of  claim 1 , wherein the membrane comprises a plurality of layers of doped and un-doped silicon carbide to provide a gradient of coefficient of thermal expansion for substantially reducing thermal stresses.  
   
   
       11 . The ignition device of  claim 1 , wherein the heating elements comprise a plurality of microwires sealed within the cavity in vacuum, or an inert environment and wherein the microwires comprise doped silicon, or tungsten, or molybdenum disilicide.  
   
   
       12 . The ignition device of  claim 11 , further comprising an anti-oxidation layer disposed adjacent to either side of the membrane for substantially preventing the membrane from oxidation at high temperatures.  
   
   
       13 . The ignition device of  claim 1 , further comprising mechanical stress relief structures to manage stress due to thermal expansion.  
   
   
       14 . The ignition device of  claim 1 , wherein the heating elements are disposed at a pre-determined distance from the membrane.  
   
   
       15 . A gas appliance, comprising: 
 a gas burner assembly configured to receive a flow of gas; and    an ignition device positioned adjacent to the gas burner assembly for igniting the flow of gas, wherein the ignition device comprises: 
 a two dimensional microplate including a membrane;  
 a plurality of heating elements embedded in the membrane, wherein the heating elements comprise a plurality of patterned resistors and wherein the plurality of heating elements are configured to heat the microplate on application of voltage to the heating elements; and  
 a cavity disposed adjacent to the heating elements and configured to provide thermal isolation of the heating elements.  
   
   
   
       16 . The gas appliance of  claim 15 , wherein the membrane comprises a non-electrically conductive material and the heating elements comprise an electrically conductive material.  
   
   
       17 . The gas appliance of  claim 15 , wherein the cavity is sealed in vacuum, or in an inert environment to substantially prevent degradation of the heating elements by oxidation.  
   
   
       18 . A method of igniting a flow of gas in a gas appliance, comprising 
 receiving the flow of gas adjacent a microplate having heating elements embedded within a membrane;    heating the microplate by applying a voltage to the heating elements embedded within the membrane; and    igniting the flow of gas via the heated microplate.    
   
   
       19 . The method of  claim 18 , wherein applying the voltage comprises applying the voltage to doped silicon carbide microscale resistors embedded within a un-doped silicon carbide membrane.  
   
   
       20 . The method of  claim 18 , further comprising sensing the temperature of the microplate via measuring a resistivity of the microplate.