Abstract: The contact surface (8') is constantly urged against the commutator (9) by spring means. The brush material is progressively worn away, without changing the shape of the contact surface (8'), owing to the rotation of the commutator (9). A cylindrical slot (17) separates the outer portion (5') of the brush body (5) from the inner portion (5b) thereof. Thus, the contact surface (8') is kept separated from the cylindrical portion (16') of the outer surface of the brush body as long as the brush material is not worn away to reach the merging zone of the portions (5a) and (5b) of the brush body. This allows a substantial limitation of the risk of sparking between the brush body and the commutator to be achieved, thus avoiding deposit of a carbon layer onto the peripheral surface of the commutator.

Abstract: The invention relates to a direct current micromotor having an iron-free rotor comprising a coil support in the form of a disc and a cylindrical coil 10 fixed at one of its ends to the periphery of this disc, the coil support bearing the collector segments and being constructed in the form of a printed circuit board 11. The collector segments are constituted by circular segments of conducting material 12 having a radial extension 13 which extends to the periphery of the disc. A peripheral connection sector 14 is separated from the sector 12 by an insulating zone 15.This arrangement enables damage to the brushing surface of the collector brushes to be avoided during manufacture, such damage being caused by a coating of welding flux or by inappropriate heating.

Abstract: A direct-current motor-generator comprises at least one stationary magnetic circuit including a permanent magnet and forming an air gap of substantially cylindrical shape, and a generally cup shaped rotor bearing a motor winding and a generator winding. The arrangement of the at least one magnetic circuit and the windings is such that the magnetic flux passing through the one of the said windings is separated in space from the flux passing through the other of the said windings.