| 摘要 |
PURPOSE: To eliminate insufficient amount of air caused by clogging at a proper timing in response to clogging condition of an air filter by controlling an electric energization indicating value according to the clogging condition of the air filter and a deviation of the number of revolutions of a blower and an aimed number of revolutions. CONSTITUTION: When an electric energization indicated value is lowered below an allowable lower limit value by clogging of an air filter 12, the allowable lower limit value is generated and outputted as indicating value. At this point, a blower 5 is energized to blow by a fixed amount and the number of revolutions of the blower 5 is increased naturally with a decrease in a load following a progress in the clogging of the air filter. As a result, a lowering of the amount of air attributed to the clogging of the air filter 12 is suppressed. The clogging of the air filter 12 further progresses and when a deviation of the detected frequency of the blower 5 by a number of revolutions sensor 18 and a target number of revolutions exceeds a specified value, the electric energization indicating value is increased to enlarge the electric energization of the blower 5 thereby securing a necessary amount of air. |
