| 摘要 |
PURPOSE:To quickly take a necessary measure and to prevent an electric fan from overheating, by a method wherein, when a part in an air flow path is clogged, its place is detected and displayed according to an output signal from a sensor and the electric fan is also controlled. CONSTITUTION:When air-permeability of a filter 15 deteriorates by dust being held in a compartment 14, in cleaning, a differential pressure detected by a No.1 sensor 38 for differential pressure increases by degrees. When a comparator 59 decides that the differential pressure is larger than a specified pressure, a controller 56 increases a speed of an electric fan 20 and compensates the deterioration of suction force because of the filter 15 clogging up. At the same time, the No.1 light emitting device 67 on a displaying device 66 is emitted and it is informed to an operator that the dust has collected in the collecting case 14. On the other hand, when large dust such as a vinyl bag, a cloth and the like is sucked and it is clogged up in a hose 25, only the differential pressure which is detected by a No.2 sensor 39 for the differential pressure, increases suddenly. When its differential pressure exceeds a specified pressure, the No.2 LED 68 on the displaying device 66 is lighted to inform the operator of clogging up. |
