| 摘要 |
PURPOSE:To prevent generation of malfunction in wear sensing due to tempera ture variation by providing a permanent magnet inside of a ball joint for arrang ing a Hall effect element sensible of the magnetic force of the permanent mag net opposed to the same to drive the Hall element with constant current. CONSTITUTION:A magnetic field due to a permanent magnet (11) stretches to the outside of a closedown plate (10), and the magnetic force of said field is sensed strongly by a Hall element (12). Supposing that a ball joint wears abnormally and the cylinder (9) of a wear compensating bearing (8) restores by its elastic spring force, a ball head (5) and the permanent magnet (11) move in the direction to a socket opening (6). Then, a facing distance (L) between the permanent magnet (11) and the Hall element (12) gets large to get weak the magnetic force detected by the Hall element (12). And when the facing distance (L) gets its set value, reached it is sensed that the ball joint (1) gets its wear limit reaches. Thus, malfunction in wear sensing due to temperature variation can be prevented substantially.
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