US Patent 9627934 Rotor windings for DC motor

A commutated DC motor (10) includes a stator (12) and a rotor (14) mounted in the stator (12). The stator (12) has 2P magnetic poles, wherein P is an integer greater than 1. The rotor (14) includes a rotor shaft (81) with a rotor core (85), and a commutator (83) fixed thereto. The rotor core (85) has multiple teeth defining m×P slots therebetween, wherein m is an odd integer greater than 1. The commutator (83) has k×m×P segments, wherein k is 1 or 2. A rotor winding (87) formed by winding a single continuous wire is received in the slots of the rotor core (85) and connected to the segments of the commutator (83), and has k×m winding units. Each winding unit includes P coils in series connection and is directly connected to only two segments.