Patent ID: 7038351

Claim:
A metal-graphite brush for supplying electricity to a coil wound around a core provided at a rotor of a motor, wherein the metal-graphite brush is made of sintered material having porosities at a surface of, or inside, the sintered material, the metal-graphite brush is infiltrated by a liquid containing a plurality of kinds of glycol ether having varying numbers of alkylene oxide structure units, the liquid having a boiling point higher than that of water, and wherein a glycol ether, selected from the plurality of kinds of glycol ether according to a temperature of a slidable contacting surface of the metal-graphite brush with a commutator for supplying electricity to the coil, is selectively vaporized, transferred toward the slidable contacting surface and supplied between the slidable contacting surface of the metal-graphite brush and the commutator.