| 摘要 |
PURPOSE:To contrive to maintain normal combustion without employing a motor with large capacity and at the same time to reduce cost by a method wherein the rate of blasting air flow of a fan to a burner is controlled so as to nearly constant within a range, in which normal combustion is maintained, when a high flow rate region, in which the quantity of fuel supplied exceeds a certain fixed value, is reached. CONSTITUTION:A fan motor drive voltage VM, which is given from an AC supply through a transformer, a rectifier 11, and a capacitor 12 to a fan motor drive circuit 2, is controlled by a motor rotational frequency setting voltage VC, which is outputted from a voltage level conversion circuit 6. VC is obtained by converting pulse signals, which are outputted from a circuit controlling the quantity of fuel supplied and have a fixed pulse interval and variable pulse lengths, through a pulse-voltage conversion circuit 4, an amplifier circuit 5, and a voltage level conversion circuit 6 to a voltage level. Because of being requested to shape the wave form, the pulse signals are shaped their wave forms by means of the pulse-voltage conversion circuit 4. |
