| 摘要 |
PURPOSE:To make the structure simple and to expand the area where combustion can be controlled by providing a flame detection positive element and a flame detection negative element both facing flame holes respectively provided on flame hole plates, and using a part of the flame detection negative element also as an ignition electrode. CONSTITUTION:Each of flame holes 18 is opposite to each of the flame holes 18 on two flame hole plates 17 facing each other, and a flame detection positive element 20 is inserted in a combustion chamber 16 near one of flame holes 18 on one of the flame hole plates 17. A negative flame detection element 21 is provided in the vicinity of flame holes 18 excepting those facing the positive flame detection element 20. A flame detection part is made up of the positive flame detection element 20, the negative element 21 and the flame hole plates 17, and connected to a combustion control device 25. An ignition electrode 27 operated by a voltage booster 26 is provided in a position opposite to the positive flame detection element 20 in longitudinal direction of the combustion chamber 16 so as to cause spark discharge at its end with the flame hole 17 as a negative electrode. The other part except the end is in contact with the flame at the time of normal combustion. Through this constitution, even when the air ratio is high and the flames float above the flame holes, the value of ionic current is not low because of the existence of the negative flame detection element in the flame. Therefore, combustion can be expanded to the range of higher air ratio. |
