Rotary circulation pump has an axially moveable motor rotor which is automatically positioned to block back circulation when in the quiescent mode

摘要

The pump motor (4) has a rotor (30) and shaft (10), axially slidable within the housing (25) and stator (26), on which an impeller (8) is fixed to pump liquid from the inlet duct (19) into the outlet duct (12). A spring (37) normally urges the rotor forwards to close off the inlet duct from the outlet duct until the motor is activated, when suction through the hollow shaft returns the rotor assembly to allow passage from inlet to outlet.