| 摘要 |
A star wheel, typically the starter gear of an internal combustion engine is magnetically coupled to a stationary pickup, for example a coil-core or yoke combination, a Hall generator, or the like. Upon rotation of the gear, or star wheel, sequential signals will be induced in the pickup which, related to time, provide an output signal representative of speed. To determine an angular reference position, an additional magnetically responsive reference element is included in the magnetic circuit formed by the stationary pickup and the teeth of the star wheel, to additionally modify the reluctance of the pickup-star wheel magnetic circuit, and change the characteristic of the output signal, for example by a phase jump, a discrete output level jump, or the like. The reference element may be a pin of soft iron, or of the material having soft iron characteristics, a pre-magnetized pin, or the like, exposed to the yoke arms of a pickup surrounding the star wheel, or otherwise magnetically coupled to the pickup.
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