Hall Sensor
Disassembled Hall sensor of the engine with a displacement of 1.8 liters. The most important details are the Hall integral system (in housing with connector) and diaphragm rotor.
In a very simplified way, we can say: the Hall sensor provides switching on and off the current to the ignition coil (bypass through the control unit and final stage). It is named after the discoverer of the Hall effect, which is used in this sensor.
The Hall sensor consists of the following parts: a diaphragm rotor, e.g. with four recesses (depending on the number of cylinders), a permanent magnet and the direct integral Hall system located opposite it. All this works like a light shutter, only here instead of light they work with electromagnetic radiation.
If the rotor diaphragm is in an electromagnetic field, then the Hall sensor starts current to the control unit. When the diaphragm moves away from the air gap between the Hall integral system and the permanent magnet, no current flows to the control unit. These are ignition signals. Hall sensor is located:
- in a 74 kW engine under the distributor;
- in the 92 kW engine and in the 110 kW four-cylinder engine, front left on the cylinder head;
- in a six-cylinder engine, at the rear on the left cylinder head.
RPM sensor and ignition timing sensor
In addition to the Hall sensor, the control unit receives information from the engine speed sensor and the ignition timing sensor (the latter only in a six-cylinder engine). Both are so-called inductive sensors.
The engine speed sensor functions as follows: a coil and a magnet are placed in the sensor. The mating part is formed by jagged hills on the flywheel ring gear at the rear of the crankshaft. Each time a tooth passes under the sensor, the magnetic field of the permanent magnet changes and voltage is applied to the coil. This small voltage signal is sufficient for further processing in the control unit. Information on the crankshaft speed is also available.
In order to determine the exact position of the crankshaft, a steel pin was placed at a specific location on the perimeter of the flywheel. When the pin passes under the sensor, a voltage peak occurs, which is used by the control unit to determine the position of the crankshaft.
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