Dynamoelectric machines

Claim 1

In a dynamoelectric machine of the type comprising a housing, a stator and rotor contained in said housing, said housing including an inlet opening and a discharge opening for cooling air, tortuous passages between said inlet and discharge openings and in the interior of said housing for preventing foreign matter in atmospheric cooling air from entering into said stator and rotor, a fan mounted on a shaft of the rotor for circulating the cooling air through said inlet opening, said tortuous passages, said stator and rotor and said discharge opening, slip rings mounted on said rotor shaft on the outside of said housing, and a casing enclosing said slip rings and defining a slip ring chamber, the interior of said housing and said slip ring chamber being separated by a portion of said housing defining a first partition wall, the improvement which comprises a second partition wall including an annular portion mounted in said housing to encircle said fan and means for circulating a portion of the cooling air circulated by said fan through another opening in said housing in said first partition wall and into said slip ring chamber, said means for circulating including conduit means defining said another opening and connecting said second partition wall to said slip ring chamber.