| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a backflow prevention system which combines the prevention of the backflow to a chamber caused by the stop of a vacuum pump and the facilitation of its restoration, and to provide a vacuum pump provided with the backflow prevention system. <P>SOLUTION: When a comparator 17 or a comparator 27 determines that the value of current flowing through an inverter circuit 13 lies in a temporary overload state by a timing t1, the closing signal of a gate valve 3 is transmitted as a pulse only for 1 second, e.g., from t1 to t2, and the gate valve 3 starts a closing operation from the t1. The overload state is temporary, and the vacuum pump 5 continuously operates without being stopped as it is in the case where it converges immediately. But, since the gate valve 3 is perfectly closed after almost 1 second by the receiving of a closing command, a monitor checks that the operation of the vacuum pump is continued in a center, and thereafter transmits the opening command of the gate valve 3 in t3. <P>COPYRIGHT: (C)2012,JPO&INPIT |
