| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that in the conventional method for controlling a rotating speed of an impeller, the rotating speed of the impeller is set high and therefore, the impeller is needlessly worn out and the impeller is decreased in the service life. <P>SOLUTION: A controller 5 reads a load current value I measured with a current measuring device 6 when the impeller 3 is rotated with the set rotating speed X<SB POS="POST">0</SB>memorized in a memory device 7, and then, in the case of determining that the read load current value I is less than a threshold value I<SB POS="POST">0</SB>memorized in the memory device 7, the rotating speed of the impeller 3 is raised up so that the load current value I becomes equal to or higher than the threshold value I<SB POS="POST">0</SB>. <P>COPYRIGHT: (C)2012,JPO&INPIT |
