A miniature motor with a frequency generator comprising a motor portion having a stator with a permanent magnet for forming a magnetic field and a rotor with rotor windings wound on a rotor core; electric current being fed to the rotor windings via a commutator making sliding contact with brushes, and a frequency generator for detecting the revolution of the motor, in which the frequency generator comprises a frequency generator rotor, mounted on the motor rotor, having a disc-like rotor portion made of a soft magnetic material and equipped with a plurality of magnetic-pole teeth on the outer periphery thereof, an internal-gear core of an annular disc shape, made of a soft magnetic material, disposed in such a manner as to come in contact with the inside of a motor housing and face the outer circumferential surface of the rotor portion and equipped with a plurality of magnetic-pole teeth on the inner periphery thereof, a permanent magnet forming a magnetic field between the magnetic-pole teeth of the rotor portion and the magnetic-pole teeth of the inner-gear core, and a frequency generator stator having frequency-detecting coils which detect changes in magnetic flux in a magnetic circuit in which the magnetic fluxes caused by the permanent magnet pass, and generate an induced voltage proportional to the revolution of the rotor portion.
A d.c. motor unit with a rotational speed detector comprising a d.c. motor (1) having an output end and an idle end, and a rotational speed detector (14) water-tightly attached to the motor output end. The d.c. motor (1) comprises a motor frame (2) including an output end and an idle end, a mounting bracket (9) attached to the output end of the motor frame (2) and a rotary shaft (4) having an idle end rotatably supported by the motor frame (2) and an output end rotatably supported by and extending outwardly through the mounting bracket (9). The rotational speed detector (14) comprises a rotary portion mounted on the output end of the rotary shaft (4) and a stationary portion mounted to the mounting bracket at the output end of the motor frame (2). The rotational speed detector (14) comprises a substantially elastic permanent magnet plate (20) for generating a magnetic flux (.phi.) extending through a closed magnetic circuit including contact surfaces which are in pressure contact with the permanent magnet plate (20).
A PMDC motor 10 with a speed sensor 20 has a cup-like deep drawn rear housing 18 and an end cap 16. The speed sensor 20 is located on an inner surface of the end cap 16 and has a coil connected to two terminals of a connector 23 mounted on a brush plate 21 of the end cap 16. The connector 23 is aligned with a window 26 in the rear housing 18.
A PMDC motor with a speed sensor has a cup-like deep drawn rear housing. The speed sensor is located at the bottom of the housing and has an annular base plate supporting a coil with a steel pin core. The coil is connected to two terminals of a connector mounted on the base plate. The connector is aligned with a window in the rear housing.
A coil assembly for sensorless rotor angular position control of a single phase permanent magnet motor. The coil assembly is positioned axially adjacent one end of the motor's rotor core in magnetic coupling relationship with the rotor and substantially independent of the magnetic coupling relationship between the main winding of the motor's stator and rotor. The coil assembly comprises a coil of wire and a coil fixture for holding the coil of wire.
