Device to detect rotation position of crankshaft; has transmitter wheel with twice number of teeth to simulate desired wheel with desired number of teeth and has differential magnetoresistive sensor

摘要

The device has a transmitter wheel (10) that simulates a desired transmitter wheel. A differential sensor (50) has two magnetoresistors (MR1,MR2) and is magnetized using permanent magnets (56). The transmitter wheel has 2n teeth (12,12') and 2n gaps, with broad gaps (14') and narrow gaps (14) arranged sequentially. The transmitter wheel rotates with respect to the sensors and is spaced from the magnetoresistors. Current sources (72,74) are connected to the differential sensor, to supply first and second output voltages (VMR1,VMR2) according to the gaps, as they pass the differential sensor. A signal processing circuit (80) is connected to the differential sensor, to deliver two different voltage outputs (0,1), where one characterises the center of a broad gap followed by the center of a narrow gap, and the other characterises the center of a narrow gap followed by the center of a broad gap. A desired transmitter wheel with n gaps and n teeth is simulated, where each tooth of the desired transmitter wheel is assigned the first voltage output and each gap of the desired transmitter wheel is assigned the second voltage output. An Independent claim is included for a method for using the device.