Abstract: A 5-phase dc motor which can be mass-produced readily at a reduced cost. The motor comprises a field magnet having four alternate north and south magnetic poles of an equal angular width, a rotor including a rotor armature core having five rotor pole shoes formed in an angularly equidistantly spaced relationship by an electrical angle of 144 degrees, a commutator including ten commutator segments provided successively on the rotor, and a pair of brushes disposed in a spaced relationship by an angular distance of 180.degree. electrical and for sliding contact with the commutator. A single conductor is electrically connected to the commutator segments and wound on the rotor pole shoes in a predetermined specific sequence to form armature windings which do not overlap with any other armature windings.

Abstract: A disk-type brushless motor comprises a 2p-pole magnet rotor (p represents an integer of 2 or more) having alternating N and S poles and a single position sensor element. A stator armature having an armature coil is formed on two conductors which contribute to the generation of torques and extend with an opening angle substantially equal to the width of each magnetic pole of the magnet rotor. A projection such as a screw for generating cogging to enable the self-start of the magnet rotor is disposed at a place somewhere short substantially by a widthPw4+n.multidot.PwwhereinPw is a width per pole of the magnet rotor, andn is a positive integer of 1 or more,from the conductor which contributes to the generation of torques toward the rotational direction of the magnet rotor.

Abstract: A brushless d.c. motor is equipped with a stator armature, which is composed of a stator yoke and at least one armature coil arranged on the stator yoke, and a 2p(p: a positive integer of 1 or more)-pole magnetic rotor facing the stator armature, rotatable relative to the stator armature and having alternating N and S poles. The motor can self-start by utilizing a cogging torque produced upon feeding a direct current to a position sensor. The stator yoke defines at such a point as permitting self-starting of the magnet rotor a cut-off portion of such a shape that ensures the self-starting of the magnet rotor and provides an ideal composite torque curve. The brushless d.c. motor enjoys easy assembly work, low manufacturing cost, compact size, good performance, good mass productivity, etc. It is suited particularly as a disk-type brushless motor or disk-type burshless fan motor.