Timing sensor

TIMING SENSOR

The Hall effect sensor is fitted to the cylinder head and faces the camshaft pulley.

An opening on the pulley allows the timing sensor to detect the engine timing position and indicate it to the injection control unit.

The injection control unit uses the timing sensor signal to detect TDC at the end of compression.

Operation

A semi-condulator layer, through which a current passes, immersed in a magnetic field (lines of force perpendicular to the direction of the current), produces a difference in power, known as Hall voltage.

If the intensity of the current remains constant, the voltage produced only depends on the intensity of the magnetic field. The intensity of the field can simply be altered periodically to produce a modulated electrical signal. Signal frequency is proportional to the speed with which the magnetic field changes.

To achieve this change, the sensor is crossed by a metal ring (inner part of the pulley) with an opening.

When it moves, the metal part of the ring covers the sensor to magnetic field and the output signal is therefore low; Conversely, the sensor generates a high signal at the opening when the magnetic field is present.

This signal, together with the rpm and TDC signals, allows the injection control unit to identify piston position and determine injection point.

AIR FLOW METER
(DEBIMETER)

The debimeter is located on the air intake sleeve and is hot film type.
The debimeter contains an intake air temperature sensor.

Operation

The principle of operation is based on a heated membrane fitted into a measurement channel through which engine intake air flows.

The hot film membrane is maintained at a constant temperature (about 120 °C higher than incoming air) by the heater coil.

The mass of air flowing through the measurement channel tends to take heat from the membrane. To keep the membrane at constant temperature, a certain current level must flow through the resistance.

Because this current is proportional to the mass of air that flows to the engine, it can be measured with a Wheatstone bridge and the resulting signal is sent to the injection control unit.

1. Covers
2. Electronic card
3. Sensor
4. Mounting plate
5. Mount
6. O-ring
7. Temperature sensor