| 摘要 |
PURPOSE:To suppress the generation of whistling sounds caused by a disturbance in the combustion flame by changing stepwise by a step in the range beforehand specified the rotational speed of a forced and exhaust fan from the rotational speed corresponding to the combustion quantity before switching according to the change in the gas pressure at the time of switching from a low combustion quantity to a high combustion quantity. CONSTITUTION:At time t0 combustion quantity is switched from a low combustion quantity to a high combustion quantity, a control device calculates a target value P1 of gas pressure which corresponds to the high combustion quantity and a final rotational speed W1 of a forced and exhaust fan which corresponds to this target value P1, and the control device changes the gas pressure from P0 which corresponds to the low combustion quantity to P1. On the other hand, a division width W3 of the fan rotational speed is selected, and the initial rotational speed W0 and the final rotational speed W1 are compared, and if (W1-W0)>Ws, a target rotational speed Wm is set at Wm=W0+Ws. In 0.1 second this value and the final rotational speed W1 are compared, and if W-(W0+Ws)>Ws, the division width Ws is added and the sum is made the target rotational speed value. This procedure is repeated at every 0.1 second to make Wm reach the final rotational speed W1. By the way if W1-W0<=Ws, the target rotational speed Wm is set at the final rotational speed W1. |
