Abstract: A spindle motor comprises a rotational member supported by bearings for rotation about a rotational axis, a rotational body and a motor rotor mounted on the rotational member for rotation therewith, and a motor stator mounted around the motor rotor. The rotational body has an outer diameter determined so that a windage loss of the rotational body is proportional to the third power of a peripheral velocity of the rotational body and an air gap diameter of the bearings and the diameter of the motor stator are determined so that the air loss of each of the bearings and the motor rotor is proportional to the square of the peripheral velocity of each of the bearings and the motor rotor at a range of constant speed of rotation of the rotational member.

Abstract: A spindle motor comprises a permanent magnet having an outer diameter, an outer circumference, and a number of poles. A stator core is disposed around and spaced from the outer circumference of the permanent magnet rotor. The stator core has a yoke portion, a number of lengthwise extending and circumferentially spaced slots, and a tooth portion between each adjacent two of the slots. The slots are disposed in close proximity to the outer circumference of the permanent magnet rotor, and a width of each of the slots in a radial direction of the stator core is smaller than a width of the yoke portion and equal to or greater than 1/20 of the outer diameter of the permanent magnet rotor. A coil has two or less turns and is comprised of a conductor disposed in the slots of the stator core.

Abstract: A brushless motor has a rotor magnet integrated with an output shaft. The armature coil unit is comprised of an integral number of coil blocks superposed with one another. Respective coil blocks have a displacement angle of X.sub.M =360.times.M/n degrees relative to a reference coil block, wherein X.sub.M denotes the displacement angle of the Mth coil block relative to the reference block, M denotes a positive integer from 1 to n-1 (the Mth coil block relative to the reference block), and n represents the number of coil blocks and is an even integer having a value of 4 or more. Each coil block shares a center angle of X.sub.2 +360/P degrees, wherein X.sub.2 denotes the displacement angle of the second coil block relative to the reference block, and P denotes the number of poles of the permanent magnet. The coil blocks are connected in series to form respective phases of the armature coil blocks such that the armature coil blocks of each phase pass an electric current in the same direction.

Abstract: In a stationary coil type direct current motor, the motor comprises a case supported by a shaft, and the case is made of magnetic material being high saturation magnetic flux density and high magnetic permeability, whereby magnetic saturation and iron loss can be reduced. The motor is further provided with a plurality of coils mounted on the inner circumference of the case, and the shaft on which a magnet is secured. The magnet is arranged so as to be spaced a predetermined gap from the coils. Furthermore, the case may be a less iron loss material constructed of two layers. A plurality of coils ace mounted on the inner circumference of the case, and the magnet secured to the shaft is spaced a predetermined gap from the coils.

Abstract: A coreless motor has a permanent magnet integrated with a casing, a commutator, and a rotor coil unit integrated with an output shaft. The rotor coil unit is comprised of an integral number of coil blocks superposed with one another. Respective coil blocks have a displacement angle of X.sub.M =360.times.M/n degrees relative to a reference coil block, wherein X.sub.M denotes the displacement angle of the Mth coil block relative to the reference block, M denotes a positive integer from 1 to n-1 (the Mth coil block relative to the reference block), and n represents the number of coil blocks and is an even integer having a value of 4 or more. Each coil block shares a center angle of X.sub.2 +360/P degrees, wherein X.sub.2 denotes the displacement angle of the second coil block relative to the reference block, and P denotes the number of poles of the permanent magnet.

Abstract: A coreless motor has a permanent magnet integrated with a casing, a commutator, and a rotor coil unit integrated with an output shaft. The rotor coil unit is comprised of an integral number of coil blocks superposed with one another. Respective coil blocks have a displacement angle of X.sub.M =360.times.M/n degrees relative to a reference coil block, wherein X.sub.M denotes the displacement angle of the Mth coil block removed from the reference block, M denotes a positive integer from 1 to n-1 (the Mth coil block removed from the reference block), and n represents the number of coil blocks and is an odd integer having a value of 3 or more. Each coil block shares a center angle of X.sub.2 +360/p degrees, wherein X.sub.2 denotes the displacement angle of the second coil block removed from the reference block, and p denotes the number of poles of the permanent magnet.

Abstract: A compact, high-torque electric motor in which one motor element (either the stator or rotor) has magnetic poles whose effective magnetic width is substantially equal and which span equal center angles. The second motor element has a plurality of armature groups, each of which occupies a phase sector of the motor element formed by dividing the total periphery by a natural number. All of the armatures within an armature group are connected electrically in series and excited with a current of one phase (either an alternating current phase or an equivalent phase generated by commutator action). Within on pole group the poles may have equal widths or different widths.

Abstract: A DC brushless motor wherein each of circular-arc pole shoes of a stator arranged facing a rotor having a cylindrical permanent magnet with N- and S-poles magnetized alternately around the circumference thereof has a narrow groove extending along almost half the length of the arc from one end thereof near the surface facing the permanent magnet. The permanent magnet provided for the rotor is constituted in such a manner that the radius of its surface facing the stator varies continuously over the length of arc of each pole shoe from one end thereof to the other.