New Generation N62 Engine
Chapter 4 P.25
Course Contents/Background Material
© BMW AG,
Service Training
- Valvetronic sensors
Each eccentric shaft is monitored by a detecting sensor. The
N62 engine has two sensors which are of the same design, and
function in exactly the same way. These are magneto-resistive
sensors (refer to N42 and M47 Tü).
These sensors are considerably more robust than Hall sensors
and therefore cope with vibrations and temperatures better.
There are two measuring sensors, two measuring and evaluation
electronic sensors and two transmitting sensors in each of the
two sensor housings.
One sensor is the guide sensor, while the other is the reference
sensor.
Both sensors cover a rotation angle of 180º of the eccentric
shaft. The signal course of the reference sensor is opposite to
that of the guide sensor.
The Valvetronic control unit supplies the guide and reference
sensors with 5 volts and the earth connection using common
wires. Each of the two sensors requires three interfaces for data
transfer:
- CS (chip select)
- DAT (data transfer)
- CLK (clock line)
There is only one clock line, but it works inside the sensor on
both the guide and reference sensor. The guide sensor transmits
the eccentric shaft positions to the Valvetronic control unit at
shorter intervals than the reference sensor.
Once the exact position of the eccentric shaft has been
recorded by the magneto-resistive bridge circuit, this value is
stored in an internal register.
The Valvetronic control unit sends the command to the guide
sensor via the CS line to transmit the data from the internal
register to the output register. The Valvetronic control unit then
sends the command to the output register via the CLK line to
transfer the data in serial.
