Rotation detection device

Abstract

The invention provides a rotation detection device detecting rotation of gears. Error detection of a rotation state can be prevented even then a magnetic sensor detecting magnetic flux density is used and air gaps between the tooth face of the gear and the magnetic field change periodically due to vibration and the like. A rotation detection device (6) includes a magnet (2) that forms a magnetic field toward a tooth surface of a gear (3); and a magnetic sensor (1) disposed between the magnet (2) and the gear (3). The magnetic sensor includes at least a pair of Hall elements that outputs signals according to a magnetic flux density in a circumferential direction of the gear (3); and a DSP that sets a first threshold Bop on the basis of signals output from the Hall elements in the case in which the distance between the tooth surface of the gear (3) and the Hall elements is set as infinite, the DSP in the magnetic sensor (1) outputting a signal according to a rotation of the gear (3) on the basis of signals output from the Hall elements according to a variation in a magnetic flux density caused by the rotation of the gear (3) and the first threshold Bop.

Description

technical field [0001] The present invention relates to a rotation detection device. Background technique [0002] As a conventional technique, a rotation detection device that detects the rotation of a gear by measuring a change in the angle of a magnetic field has been proposed (see Patent Document 1, for example). [0003] The rotation detection device disclosed in Patent Document 1 includes a magnet forming a magnetic field toward a tooth surface of a gear, and a magnetic sensor provided between the gear and the magnet for detecting a change in the angle of the magnetic field according to the rotation of the gear. As the gear rotates, the signal output from the magnetic sensor changes periodically, whereby the rotational speed, angular velocity, etc. of the gear can be detected. In addition, since a change in the magnetic field angle is detected, the occurrence of false detection of the rotational state can be prevented even if the air gap between the tooth surface of t...

AI Technical Summary

Problems solved by technology

Therefore, this device prevents the occurrence of false detection of the rotational state of the gear even if the air gap changes periodically, but this device cannot be applied to the occasion where a magnetic sensor is used to detect the magnetic flux density, and thus, causes when the gear The problem that the occurrence of false detection cannot be prevented when the air gap between the tooth surface and the magnetic sensor changes periodically due to vibration, etc.

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