1. An ignition system for a gas appliance, comprising:
- an ignition controller coupled to a power source;
- an ignitor coupled to said ignition controller, the ignitor receiving a current from the ignition controller; and
- a valve, coupled to said ignition controller,
- wherein the ignition controller comprises means for activating the valve when said current received by the ignitor is greater than a first current value and less than a second current value.
2. The ignition system of claim 1, further comprising:
- a burner coupled to said valve to receive a flow of gas, said ignitor located adjacent to said burner.
3. The ignition system of claim 1, wherein said ignitor comprises a material having a resistance that increases as the temperature of said material increases.
4. The ignition system of claim 1, wherein said ignitor comprises an insulating ceramic, a semiconductive ceramic, and a metallic conductor.
5. The ignition system of claim 1, wherein said ignitor is selected from the group consisting of SiC--MoSi.sub.2 --AlN and SiC--MoSi.sub.2 --Al.sub.2 O.sub.3.
6. The ignition system of claim 1, wherein said ignitor comprises SiC--MoSi.sub.2 --AlN.
7. The ignition system of claim 1, wherein said means for activating the valve comprises:
- a first relay that closes when said current is greater than the first current value (I.sub.1); and
- a second relay that opens when said current is greater than the second current value (I.sub.2), wherein I.sub.2 is greater than I.sub.1, wherein said valve releases a flow of gas when said current is between I.sub.1 and I.sub.2.
8. The ignition system of claim 1, wherein said means for activating the valve comprises:
- a multi-position relay that activates the valve when said current is greater than the first current value (I.sub.1) and less than the second current value (I.sub.2), wherein said valve releases a flow of gas when said current is between I.sub.1 and I.sub.2.
9. The ignition system of claim 1, further comprising:
- a valve actuation circuit coupled to said ignition controller and said valve, said valve actuation circuit comprising a relay.
10. The ignition system of claim 1, further comprising:
- a timing controller coupled to said ignition controller to synchronize the ignitor reaching a predetermined temperature and the opening of said valve.
11. The ignition system of claim 1, wherein said ignitor comprises a pressure-sintered composite material.
12. The ignition system of claim 1, wherein the ignitor comprises a resistive material disposed between two ceramic members.
13. A gas oven, comprising:
- an ignition controller coupled to a power source;
- an ignitor coupled to said ignition controller, the ignitor receiving a current from the ignition controller;
- a valve, coupled to said ignition controller,
- wherein the ignition controller comprises means for activating the valve when said current received by the ignitor is greater than a first current value and less than a second current value; and
- a burner coupled to said valve to receive a flow of gas.
14. The oven of claim 13, wherein the ignitor comprises a pressure-sintered composite material.
15. The oven of claim 13, wherein the ignitor comprises a resistive material disposed between two ceramic members.
16. The oven of claim 13, wherein said means for activating the valve comprises:
- a first relay that closes when said current is greater than the first current value (I.sub.1); and
- a second relay that opens when said current is greater than the second current value (I.sub.2), wherein I.sub.2 is greater than I.sub.1, wherein said valve releases a flow of gas when said current is between I.sub.1 and I.sub.2.
17. The oven of claim 13, wherein said means for activating the valve comprises:
- a multi-position relay that activates said valve when said current is greater than the first current value (I.sub.1) and less than the second current value (I.sub.2), wherein said valve releases a flow of gas when said current is between I.sub.1 and I.sub.2.
18. The oven of claim 13, wherein said ignitor comprises a material selected from the group consisting of SiC--MoSi.sub.2 --AlN and SiC--MoSi.sub.2 --Al.sub.2 O.sub.3.
19. A method for controlling the ignition of a burner with an ignitor, the ignitor having a resistance characteristic in which resistance increases with temperature, the method comprising:
- providing a current (I) to the ignitor; and
- opening a valve that releases a flow of gas to the burner when the current (I) is greater than a first current value (I.sub.1) and less than a second current value (I.sub.2), wherein I.sub.1 is less than I.sub.2, wherein the ignitor ignites gas flowing from the burner when I.sub.1 <I<I.sub.2.
20. The method of claim 19, wherein the ignitor comprises a pressure-sintered composite material.
21. The method of claim 19, wherein the ignitor comprises a resistive material disposed between two ceramic members.
22. The method of claim 19, further comprising:
- synchronizing the opening of the valve with the ignitor reaching a predetermined temperature.
23. The method of claim 19, wherein the ignitor is within a predetermined temperature range when I.sub.1 <I<I.sub.2.
24. The ignition system of claim 1, wherein the means for activating the valve activates the valve based on the magnitude of the current through the ignitor.
25. The oven of claim 13, wherein the means for activating the valve activates the valve based on the magnitude of the current through the ignitor.
