Rotation angle Detektierapparat

Rotation angle Detektierapparat, comprising a magnet (46) which is provided in a main gear (41) and a magnetic detector (39) positioned for facing the magnet (46). The magnet (46) rotates integrally with the main gear (41), and the magnetic detector (39) detects changes in the magnetic field of the magnet (46) so that a rotation angle of the main gear (41) is detected. The main gear (41) has a recessed portion (41a) with base and a plurality of mounting pins (41c) (41a) are arranged in the recessed part. The magnet (46) is in the recessed part (41a) is used, so that a part of the magnet (46) from an upper end of the recessed part (41a) protrudes. The magnet (46) in the recessed part (41a) is inserted is pressed against the main gear (41) by an elastically deformable holding plate (47) which is made of a non-magnetic material. An outer portion (47b) of the holding plate (47) has a plurality of mounting holes (47d). The magnet (46) in the recessed part (41a) is inserted, is pressed against the main gear (41) by the elastically deformed support plate (47), and each mounting bolt (41c) formed in the mounting holes (47d) used is , is thermally caulked, so that the magnet (46) is secured to the main gear (41).