| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve the efficiency of and reduce the weight of a drainage pump having the possible smallest size and simplest structure and remove torque fluctuation caused by frequency by arranging a motor whose rotational speed is gradually increased at the starting time of the pump. SOLUTION: A motor 13 which increases its rotational speed gradually at start of a pump is used so that the rotational speed of a blade 121 gradually reaches normal rotational speed from a stop state. Cavitation of air and water inside a water discharge pump is loosened. Pumping is gradually performed without striking of drain water containing a large amount of air with the rotating blade 121, which may be caused by abrupt entering of the drain water into the pump. The water discharge pump does not generate abnormal noises and vibrations from the time of pumping to the time stating water supply. It is possible to gradually decelerate the rotation by the use of the dc motor 13, and possible to reduce size and weight of the pump, and suppress abnormal noises and vibrations.</p> |
