US Patent 10550847 Mixed-flow or diagonal ventilating fan with consistent cooling

A self-cooling diagonal ventilating fan (30; 130) has a fan housing (36) and a fan wheel (80), rotatable around a rotation axis (168), that has, associated with it, an electronically commutated motor (73) which has an internal stator (64) and an external rotor (68, 152). Cooling air, after it emerges from the electric motor (73), is drawn through at least one opening (90) formed in the fan wheel (80) to the outer side of the fan wheel (80), in order, during operation, to maintain a constant cooling air stream (158) in a consistent flow direction through the internal stator (64) of the electric motor (73), regardless of possible backpressure.