Abstract: An AC dynamo electric machine for a motor vehicle includes an AC dynamo machine body 100 composed of a rotor 10 constituted by a first rotatable shaft 12 supported rotatably by a pair of bearings 16, 17, a rotor core 8 fixedly secured to the first rotatable shaft 12 and a field winding 9 wound on the rotor core 8, a stator 3 composed of a stator core 1 disposed in opposition to the rotor 10 and a polyphase stator winding 2 wound on the stator core 1 and a bracket 80 supporting the pair of bearings 16, 17 and the stator 3, and a rotational position detector for the control purpose composed of a second rotatable shaft 30 coupled to the first rotatable shaft 12 through a large magnetic reluctance portion 32, 33, a second rotor 21 fixedly secured to the second rotatable shaft 30 and a second stator winding 22a for generating an output voltage based on rotation of the second rotor 21.

Abstract: According to the present invention, a moving element Ai such as an electrostatically driven actuator is displaced by supplying a drive signal thereto. Meanwhile, a displacement sensing section 6 senses its displacement and a calibrating section 15 automatically calibrates the correlation between the drive signal and the displacement, thereby compensating for a variation in the characteristic of the actuator with time and according to the environment. A switching section 7 selectively connects the single displacement sensing section to a plurality of moving elements Ai one after another, thereby cutting down the circuit for displacement sensing.

Abstract: An end surface of a rotor core is offset from an end surface of a stator core by a predetermined amount in an axial direction going away from Hall ICs. In an operating condition of the motor, magnetomotive forces generating from the stator core induce a thrust force acting on the rotor core. The gap (i.e. distance) between the magnet and the Hall ICs does not exceed a pre-designated appropriate distance, and is stably maintained at a constant level (or range). In other words, the gap (i.e. distance) between the magnet and the Hall ICs can be accurately maintained at the pre-designated appropriate distance by utilizing the magnetic attraction force generating from the stator core.