Ducted rotor and lamination with deep radial passageway

Abstract

A squirrel cage rotor, and a lamination is disclosed, wherein cooling ducts and passages are provided in the rotor. A first rotor section may be of standard laminations and only one type of duct section has radially extending passageways between fingers. The entire duct section is made from a plurality of laminations having such fingers radially extending from the central core portion of the individual laminations so that the radial passageways extend to the inner wall of longitudinal ventilating ducts. In the outer ends of each finger a rotor bar aperture is formed so that the finger is a casing for such rotor bar. Initially, each duct lamination has a unitary bridge at the outer periphery joining adjacent fingers to add rigidity to the fingers. The assembled stacks of laminations making the two rotor sections are then cast with molten metal, e.g., aluminum, under low pressure to form a squirrel cage. Afterward, the rotor periphery is machined to remove the unitary bridges and to open the spaces between the fingers to act as radial vent passageways. These passageways communicate with longitudinally extending vent ducts within the rotor.