Component Description For Rail Pressure Sensor - Mercedes-Benz OM 471 Introduction Into Service Manual

GF07.04>W>6253H
ENGINES 471.9 in MODEL 963
Location
B622 Rail pressure sensor
The rail pressure sensor (B622) is located at
the front on the rail.
Task
The engine management (MCM) control
unit (A4) determines the current rail
pressure via the rail pressure sensor (B622).
Design
1 Sensor element
2 Sensor membrane
3 Hybrid element
B622 Rail pressure sensor
Function
The rail pressure operates on the sensor element (1) of the hybrid
element (3) and distorts the sensor membrane (2).
There are four pressure>dependent resistances (strain measuring
resistors) on the sensor membrane (2). Its bridge circuit is supplied
with voltage by an electronic analysis system which also serves for
signal amplification and signal correction. The electronics analysis
system itself is provided with a 5 V DC voltage by the engine
management (MCM) control unit (A4).
The resistors in the sensor membrane (2) are arranged in such a
way that on deforming the sensor membrane (2) two resistors are
clinched and two resistors elongated.
i Introduction of engine OM 471 and exhaust aftertreatment > 09/2011 >

Component description for rail pressure sensor

– This printout will not be recorded by the update service. Status: 09 / 2011 –
System components
Contraction and elongation changes the electrical resistance of
the resistors which in turn has effects upon the measurement
voltage, which is being applied to the electronic analysis system.
The electronic analysis system amplifies the measurement voltage,
compensating for possible temperature fluctuations or balancing
out possible manufacturing tolerances on the resistances and
passes on the cleared out measurement voltage to the engine
management (MCM) control unit (A4) which uses it to derive the
current rail pressure.
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