| 摘要 |
PURPOSE:To increase a combustion amount regulating ratio and to stabilize an air-fuel ratio, by a method wherein according to the load of a burner, either an air amount regulating means or a gas amount regulating means is controlled, and the other is controlled according to a difference between two output signals from a differential pressure signal discriminating circuit. CONSTITUTION:A first pressure guiding hole 13 in a differential pressure sensor 12 is connected to the common port of a 3-way switching valve 14, and a first state port of the 3-way pressure switching valve 14 is connected to a gas passage on the upstream side of a gas throttle 5. A second state port is connected to a second pressure guiding hole 15 of the differential pressure sensor 12, and is further connected to an air passage on the upstream side of an air throttle 2. An output signal from the differential pressure sensor 12 is inputted to a differential pressure signal discriminating circuit 17 through a differential pressure sensor detecting circuit 16, and two signals from a differential pressure signal discriminating circuit 17 are respectively inputted to the positive-phase and the negative-phase of a differential amplifier 18. An output signal from the differential amplifier 18 is inputted to an air-fuel ratio regulting circuit 19, and a gas proportional control valve 10 is operated by means of the output thereof. |
