Rotation speed detection device having a rotation angle detector of inductive type

A rotation speed detection device comprising:

• stator means having a plurality of primary poles arranged in a predetermined arrangement, a secondary pole, primary coils being wound on respective primary poles and a secondary coil being wound on the secondary pole, said poles having end portions;
• rotor means of such configuration as to oppose the end portions of the respective primary poles and the secondary pole with gaps therebetween, change reluctance of magnetic paths passing the respective primary poles in accordance with a rotation angle and receive a rotational movement or displacement by rotation which is an object of detection from outside;
• a first circuit for exciting each of said primary coils with one of a plurality of reference AC signals, each pole excitation signal being out of phase with the excitation signal of adjacent poles by a predetermined electrical angle and thereby producing in the secondary coil an output signal resulting by phase modulating the reference AC signals in accordance with the rotation speed of said rotor means;
• a second circuit for detecting the rotation speed of said rotor means in accordance with the difference in frequency or period between the reference AC signals and the output signal of the secondary coil;
• and
• a memory circuit for temporarily storing the rotation speed data having been detected by said second circuit, and a third circuit for detecting rotation acceleration of said rotor means in accordance with the difference between the rotation speed data temporarily held in said memory circuit and rotation speed data which has been newly detected by said second circuit.

A rotation speed detection device comprising:

• stator means having a plurality of poles which include end portions, said poles being arranged in a predetermined arrangement, said stator means further having primary coils being wound on respective poles and secondary coils being wound on the respective poles in association with the respective primary coils;
• rotor means of such configuration as to oppose the end portions of the respective poles with gaps therebetween, change reluctance of magnetic paths passing the respective poles in accordance with a rotation angle and receive a rotational movement or displacement by rotation, which is an object of detection from outside;
• a first circuit for exciting each of said primary coils with one of a plurality of reference AC signals, each pole excitation signal being out of phase with adjacent poles by a predetermined electrical angle;
• a second circuit for summing outputs of the respective secondary coils and thereby generating an output signal resulting by phase shifting the reference AC signals in accordance with a present rotation angle of said rotor means;
• a third circuit for digitally detecting the phase difference between a predetermined one of the reference AC signals and the output signal from the second circuit to obtain detected digital phase difference data as absolute rotation angle data;
• a fourth circuit for detecting the rotation speed of said rotor means on the basis of the change of said detected absolute rotation angle data;
• a memory circuit for temporarily storing the rotation speed data having been detected by said fourth circuit;
• and
• a fifth circuit for detecting rotation acceleration of said rotor means in accordance with the difference between the rotation speed data temporarily held in said memory circuit and rotation speed data which has been newly detected by said fourth circuit.