Abstract: A commutator includes a substantially tubular insulating core, a first slip ring fixed to the core, a plurality of first bars electrically connected to the first slip ring, a second slip ring fixed to the core, and a plurality of second bars electrically connected to the second slip ring. The first bars and the second bars are fixed to the outer surface of the core and are alternately arranged at equally spaced intervals in the circumferential direction of the core. The first slip ring and the second slip ring are arranged on the same side of the first bars and the second bars. The first and second slip rings respectively comprise a contact surface that is substantially perpendicular to the axis of the commutator and is configured for contacting brushes.

Abstract: An electric motor includes an inner stator including inner magnetic poles arranged circumferentially, an outer stator including outer magnets arranged circumferentially, and a rotor rotatably disposed between the inner and outer stators. The rotor includes a shaft, a rotor core fixed to the shaft and a winding wound on the rotor core. The rotor core includes a ring shaped yoke having a plurality of inner teeth extending inwardly and a plurality of outer teeth extending outwardly. The winding includes a plurality coils each including an inner side received in a corresponding inner slot formed between adjacent inner teeth and an outer side received in a corresponding outer slot formed between adjacent outer teeth.

Abstract: A cooling device includes an inner sleeve with an outer surface, an outer sleeve surrounding the inner sleeve, and two end portions extending between the inner sleeve and the outer sleeve at the ends. The inner sleeve, the outer sleeve and the end portions define a peripheral space. A flow guiding structure defines N channels in the peripheral space for coolant to flow, where N is an integer equal to or greater than 1. Each channel has at least two branches, and N pairs of inlet and outlet corresponding to the N channels. The branches of each channel are in fluid communication with a respective pair of inlet and outlet. Each branch extends over a half circumferential part of the outer surface of the inner sleeve. An electric motor incorporating the cooling device is also provided.

Abstract: A commutator includes a substantially tubular insulating core, a first slip ring fixed to the core, a plurality of first bars electrically connected to the first slip ring, a second slip ring fixed to the core, and a plurality of second bars electrically connected to the second slip ring. The first bars and the second bars are fixed to the outer surface of the core and are alternately arranged at equally spaced intervals in the circumferential direction of the core. The first slip ring and the second slip ring are arranged on the same side of the first bars and the second bars. The first and second slip rings respectively comprise a contact surface that is substantially perpendicular to the axis of the commutator and is configured for contacting brushes.

Abstract: An electric motor includes an inner stator including inner magnetic poles arranged circumferentially, an outer stator including outer magnets arranged circumferentially, and a rotor rotatably disposed between the inner and outer stators. The rotor includes a shaft, a rotor core fixed to the shaft and a winding wound on the rotor core. The rotor core includes a ring shaped yoke having a plurality of inner teeth extending inwardly and a plurality of outer teeth extending outwardly. The winding includes a plurality coils each including an inner side received in a corresponding inner slot formed between adjacent inner teeth and an outer side received in a corresponding outer slot formed between adjacent outer teeth.

Abstract: A cooling device includes an inner sleeve with an outer surface, an outer sleeve surrounding the inner sleeve, and two end portions extending between the inner sleeve and the outer sleeve at the ends. The inner sleeve, the outer sleeve and the end portions define a peripheral space. A flow guiding structure defines N channels in the peripheral space for coolant to flow, where N is an integer equal to or greater than 1. Each channel has at least two branches, and N pairs of inlet and outlet corresponding to the N channels. The branches of each channel are in fluid communication with a respective pair of inlet and outlet. Each branch extends over a half circumferential part of the outer surface of the inner sleeve. An electric motor incorporating the cooling device is also provided.