| 摘要 |
PURPOSE:To obtain a remarkably small-sized and compact pump apparatus by arranging a valve device in a bypath passage formed in a diffuser. CONSTITUTION:When the amount of discharge of water reduces markedly, the pressurization action of a diffuser 4 is improved markedly, and the pressure in a suction chamber 11 increases over the pressure at a suction port 21, and a large amount of water in the suction chamber 11 flows backward through a bypath passage 7, and at the same time, the diffuser 4 shifts towards the suction port side 21 against its dead load, and a collar part 41 contacts onto the seat surface of a valve seat 23. Therefore, the pressure at the suction port 12 increases markedly. Accordingly, the pressure at the discharge port 12 increases up to the off-pressure of a pressure switch 9, which is turned OFF to stop a centrifugal pump 1. |
