| 摘要 |
PROBLEM TO BE SOLVED: To provide a fan filter unit which stably starts in a short time without receiving effects of wind pressure caused by mutual interference of all fans, after power is supplied, even when plural fans driven by a sensor-less DC motor are loaded on it. SOLUTION: By closing a damper 9 driven by a second motor 8 mounted to a supply opening 7 of a casing of four fans 4a, 4b, 4c, 4d driven by a sensor- less DC motor, after power supply until the fans 4a, 4b, 4c, 4d rotate at a given target rotation speed, each of the fans 4a, 4b, 4c, 4d can be driven in a short time at the target rotation speed without receiving effects of mutual wind pressure. |
