Axially sliding contact type of a commutator, a rotor including the commutator, and an electric motor having the rotor

A rotor for an electric motor comprising:

• a bearing holder which includes a guide portion extending outwardly from a periphery of the bearing holder, for receiving a bearing;
• a plurality of air-core coils which is mounted on a surface of the guide portion, for generating a rotation force;
• and
• a commutator which is mounted on the periphery of the bearing holder, of which a surface comes in close contact with the other surface of the guide portion of the bearing holder, and which comprises:
• a plurality of metal plates made of copper;
• a separate layer which is plated on the metal plates, the separate layer being made of non-magnetic substance;
• and a plating layer which is coated on the separate layer, the plating layer being formed with noble metal.

An electric motor comprising:

• a bracket including a brush base;
• a magnet which is disposed on the bracket and on the brush base;
• a rotor assembly which is rotatably mounted on the bracket, the rotor assembly including an axially sliding contact type of a commutator;
• a brush which extends between the brush base and the rotor assembly, for supplying electricity to the rotor assembly;
• and
• a case which is combined with the bracket, for covering the rotor assembly.