Sensors - ECU Master EMU User Manual

SENSORS

In case of sensors used in cars' electric installations, we are dealing with several types:
resistance sensors,
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voltage sensors,
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magneto-inductive sensors,
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optical sensors / Hall's,
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Resistance sensors are used to measure temperatures (e.g. temperature of cooling liquid) or the
position of a throttle (TPS sensors). Voltage sensors are characterised by the fact that the value
they measure is expressed in voltage. Such sensors include the sensor of absolute pressure in the
intake manifold or the knock sensor.
The key sensors, from the point of view of engine's management work, are sensors of crankshaft's
positions and/or of camshaft, thanks to which it is possible to read the speed of the engine and to
control the ignition angle and injection.
The most popular sensor of this type is the variable reluctant (VR) sensor. It works on the principle
of inducing the electromotive force in the winding of sensor's coil wound on a permanent magnet,
under the influence of ferromagnetic movement of the impulse wheel. The induced voltage is
proportional to the sensor's distance from the impulse wheel and its rotational speed.
Scope trace of VR sensor output using trigger wheel 60-2
Page 36
VR Sensor
VR Sensor