An electrical contact device includes a high electric potential-side contact and a low electric potential-side contact having a lower electric potential than the high electric potential-side contact. The high electric potential-side contact and the low electric potential-side contact are configured to be brought into and out of contact with each other. At least one of the high electric potential-side contact and the low electric potential-side contact is formed of a low-boiling point material whose boiling point is lower than 2562 C. or a mixed material that contains the low-boiling point material.

A DC motor is provided for use in a starter that starts an ermine. The DC motor includes a commutator and a brush. The commutator is formed of copper or a copper alloy whose copper percentage content is higher than or equal to 99 mass %. The brush is arranged in sliding contact with a surface of the commutator. Moreover, the brush is formed of a sintered compact that contains graphite, copper and at least one metal sulfide solid lubricant. The percentage content of copper in the sintered compact is 30-70 mass %. The at least one metal sulfide solid lubricant includes tungsten disulfide. The percentage content of tungsten disulfide in the sintered compact is higher than or equal to 6.5 mass %.

A DC motor is provided for use in a starter that starts an ermine. The DC motor includes a commutator and a brush. The commutator is formed of copper or a copper alloy whose copper percentage content is higher than or equal to 99 mass %. The brush is arranged in sliding contact with a surface of the commutator. Moreover, the brush is formed of a sintered compact that contains graphite, copper and at least one metal sulfide solid lubricant. The percentage content of copper in the sintered compact is 30-70 mass %. The at least one metal sulfide solid lubricant includes tungsten disulfide. The percentage content of tungsten disulfide in the sintered compact is higher than or equal to 6.5 mass %.

An electric motor-generator with a plurality of field coils spaced about the periphery of a stator, and a plurality of permanent magnets spaced about the periphery of each of a pair of rotors, the pair of rotors disposed one on each side of the stator, such that during rotation of the rotors, a center of each magnet generally passes across a center of each coil. The magnets arrayed on respective rotors in alternate pole orientation N-S S-N, the magnets of one rotor offset from the magnets of the other rotor by one pole orientation, such that as a N pole on the one rotor is passing directly across one end of a field coil, a S pole of a corresponding magnet on the other rotor is passing directly across the other end of the field coll. A rotary electrical switch enables paired alternating periods of current flow and no current flow into respective stator field coils, such that in a period pair the period of current flow is shorter than the period of no current flow. A series of high capacity capacitors is wired in parallel with the field coil power supply such that the capacitors alternately discharge into the field coils when the field coils are switched on In a motor mode, and the capacitors are charged by power from the field coils when the field coils are switched off and are operating in a generator mode.

An electric motor-generator with a plurality of field coils spaced about the periphery of a stator, and a plurality of permanent magnets spaced about the periphery of each of a pair of rotors, the pair of rotors disposed one on each side of the stator, such that during rotation of the rotors, a center of each magnet generally passes across a center of each coil. The magnets arrayed on respective rotors in alternate pole orientation N-S S-N, the magnets of one rotor offset from the magnets of the other rotor by one pole orientation, such that as a N pole on the one rotor is passing directly across one end of a field coil, a S pole of a corresponding magnet on the other rotor is passing directly across the other end of the field coll. A rotary electrical switch enables paired alternating periods of current flow and no current flow into respective stator field coils, such that in a period pair the period of current flow is shorter than the period of no current flow. A series of high capacity capacitors is wired in parallel with the field coil power supply such that the capacitors alternately discharge into the field coils when the field coils are switched on In a motor mode, and the capacitors are charged by power from the field coils when the field coils are switched off and are operating in a generator mode.

An electric motor-generator with a plurality of field coils spaced about the periphery of a stator, and a plurality of permanent magnets spaced about the periphery of each of a pair of rotors, the pair of rotors disposed one on each side of the stator, such that during rotation of the rotors, a center of each magnet generally passes across a center of each coil.

The magnets arrayed on respective rotors in alternate pole orientation N-S S-N, the magnets of one rotor offset from the magnets of the other rotor by one pole orientation, such that as a N pole on the one rotor is passing directly across one end of a field coil, a S pole of a corresponding magnet on the other rotor is passing directly across the other end of the field coil.

An electric motor-generator with a plurality of field coils spaced about the periphery of a stator, and a plurality of permanent magnets spaced about the periphery of each of a pair of rotors, the pair of rotors disposed one on each side of the stator, such that during rotation of the rotors, a center of each magnet generally passes across a center of each coil.

The magnets arrayed on respective rotors in alternate pole orientation N-S S-N, the magnets of one rotor offset from the magnets of the other rotor by one pole orientation, such that as a N pole on the one rotor is passing directly across one end of a field coil, a S pole of a corresponding magnet on the other rotor is passing directly across the other end of the field coil.

Provided is a rotor of a brushed motor capable of reducing the occurrence of contamination during press-fitting of a commutator onto a knurling and reducing defect factors due to rotor contamination to improve productivity. In a rotor of a brushed motor having a commutator press-fitted onto a knurling of a shaft, an inclined surface is provided on an inner circumferential side of the commutator, and an angle of the inclined surface is configured to be smaller than an angle of an axial end portion of the knurling. The knurling may be configured to be at a position different from a shaft stepped end surface of the shaft and the knurling may be configured to be positioned axially inward of the commutator from an end surface of the commutator.

Provided is a rotor of a brushed motor capable of reducing the occurrence of contamination during press-fitting of a commutator onto a knurling and reducing defect factors due to rotor contamination to improve productivity. In a rotor of a brushed motor having a commutator press-fitted onto a knurling of a shaft, an inclined surface is provided on an inner circumferential side of the commutator, and an angle of the inclined surface is configured to be smaller than an angle of an axial end portion of the knurling. The knurling may be configured to be at a position different from a shaft stepped end surface of the shaft and the knurling may be configured to be positioned axially inward of the commutator from an end surface of the commutator.

A rotor includes coils that are formed by winding wires around bobbins of a core, terminals which are arranged on the bobbins and to which end portions of the wires are hooked, and a commutator arranged at an end portion of the core on a side where the terminals are arranged. The terminals and commutator segments of the commutator are electrically connected via metal pieces extending from the commutator segments and via a wiring board.