US Patent 7652402 Brushless motor

A plurality of coils wound around a stator magnetic-pole core are connected together and connected to output wires by use of a bus bar. The bus bar having a generally cylindrical body portion is disposed at one axial end of the stator magnetic-pole core, around which the coils are wound such that clearances are formed within magnetic-pole core slots, with an axial clearance formed between the bus bar and the coils. The body portion has such a radial dimension that at least a portion of the clearances within the magnetic-pole core slots is left uncovered. Air holes are formed in the motor housing on opposite sides of the stator magnetic-pole core to thereby form cooling air passages extending through the magnetic-pole core slots.