Rotary liquid pump, impeller / shaft assembly and flexible impeller pump assembly therefor

摘要

A pump housing has a plurality of chambers (34,52) formed therein, and a shaft (42) journaled within, the shaft having impellers keyed thereto. Each chamber has one of the impellers (32,60) disposed therein. One of the impellers (32) is the primary liquid-working element, and has rigid vanes. The vanes are generously spaced apart from the enclosing chamber (34) walls. A second impeller (60) has flexible vanes (61), and serves as a priming element; it has an intimate fit in its chamber (52) and cooperates with an outlet flapper valve (28) to create a negative pressure in the liquid inlet. Consequently, the pump can self-prime even when absolutely dry. IMAGE