| 摘要 |
PURPOSE:To reduce costs by making a transformer for ignition plugs simultaneously serve as a converter for a flame sensor so as to avoid waste of a control circuit. CONSTITUTION:When a high d.c. voltage is impressed on a flame face sensor 6 by a constant-voltage circuit 72 connected to the other end of the secondary coil 78b of a transformer T, if the combustion flame of mixture generated by igniting it with an ignition plug has reached to the flame face sensor 6, a current flows between electrodes by the ions of charged particles. By detecting the presence of this current by a detecting circuit 73, it can be detected that the flame has reached to the flame face sensor 6. Further, since the current value due to the ions in flames is remarkably small, the voltage of capacitors C1 and C2 charged by the discharge current of the ignition plug can be maintained sufficiently high. Thus, a constant d.c. voltage can be supplied to the flame face sensor 6, making the transformer T for ignition plugs simultaneously serve as a converter for a flame sensor so as to avoid waste of a control circuit, and cost reduction can be achieved. |
