Automatic dishwasher with a pump having a selectively adjustable impeller clearance

摘要

An automatic dishwasher includes a cabinet enclosing an interior washing chamber with a pump mounted in the cabinet for pumping liquids into and out of the washing chamber. The pump includes a housing having spaced apart walls and a rotatable motor shaft extending into the housing from a first one of the walls. A rotatable impeller is mounted for longitudinal movement along the motor shaft and is keyed to rotate with the motor shaft between the spaced apart walls of the housing. A removable bearing mount that supports a thrust bearing is threaded into the pump housing and, with the thrust bearing, provides an axial stop for limiting the movement of the impeller along the motor shaft. The bearing mount also includes an annular surface disposed near the exposed edges of the blades of the impeller and spaced therefrom by a predetermined, desired clearance or gap. The optimization of the clearance maximizes the efficiency of the pump. This clearance is automatically provided in a final pump assembly step when the bearing mount is threaded into place in engagement with the pump housing.