Rotation detecting device and bearing having rotation detecting device

摘要

Provided are a rotation detecting device that highly precisely detects absolute angle with low noise, as well as a bearing assembly with such a rotation detecting device. Such a rotation detecting device includes magnetic encoders arranged coaxially with different number of magnetic poles as well as magnetic sensors that detect magnetic fields of those encoders. Each of the magnetic sensors can detect the encoders within each magnetic pole, and includes sensor elements as well as a phase detector that determines the phase of the sensor element in reference to a detected magnetic field signal and then outputs an ABZ phase signal. Such a rotation detecting device further includes a phase difference detector that determines a phase difference of the magnetic field signals in reference to an output from the phase detectors and an angle calculator that calculates the absolute angle of the encoders based on the detected phase difference.

主权项

1. A rotation detecting device comprising:
a plurality of magnetic encoders arranged in a coaxial ring arrangement and having respective number of magnetic poles different from each other; a plurality of magnetic sensors for detecting respective magnetic fields of those magnetic encoders, each of the magnetic sensors having a function of detecting information on the position of the magnetic encoders within each of the magnetic poles, each of the magnetic sensors includes a plurality of sensor elements arranged at respective positions displaced from each other within the pitch of the neighboring magnetic poles, each of the sensor elements is configured to obtain two phase signal outputs representative of sine and cosine curves and to accomplish detection of the position within the magnetic poles by interpolation between the two phase signal outputs, and a phase detector for determining the phase of the magnetic field signals in reference to the magnetic field signals detected by the sensor elements and outputting an ABZ phase signal including A-phase and B-phase pulse signals A and B, which are displaced 90° in phase from each other, and a Z-phase pulse signal Z indicative of start position; a phase difference detector for determining a phase difference of the magnetic field signals in reference to an output from the phase detectors; and an angle calculator for calculating the absolute angle of the magnetic encoders based on the phase difference so detected.