Rail Pressure Sensor

Rail Pressure Sensor

Rail pressure sensor
The rail-pressure sensor is threaded into the end of the fuel-distribution rail. and delivers information on the fuel pressure downstream of the high pressure pump to the engine control. The rail-pressure sensor supports the rail-pressure control process. The signal from the rail pressure sensor is an important input signal for the engine control for activating the quantity control valve. The quantity-control valve is a component within the high-pressure pump.

Functional description
Strain gauge are used for detecting the pressure. A steel membrane equipped with strain gauge in the sensor is deformed by the adjacent pressure. The changes in resistance in the strain gauge are electronically detected by a Wheatstone bridge and evaluated. The measured voltage is then used as an actual value in the rail pressure control.







Structure and inner electrical connection
The rail pressure sensor is connected via a 3-pin plug connection.
The sensor is supplied with 5 Volts by the engine control.







Characteristic curve and setpoint values
The information on the rail pressure is transmitted to the engine control on a signal line. The effective signal for rail pressure fluctuates according to pressure levels. The measuring range of approx. 0.5 - 4.5 volts corresponds to a rail pressure of between 0 kPa (0 bar) and 25 MPa (250 bar).







Observe the following setpoint values for the rail pressure sensor:

Size Value
Voltage range of rail 0.5 to 4.5 volts
pressure sensor

Measuring range of rail 0 to 250 bar
pressure

Maximum output current 10 mA

Temperature range -40 °C to 140 °C

Diagnosis instructions

Failure of the component

If the rail pressure sensor fails, the following behavior is to be expected:
- Fault entry in the engine control unit
- Emergency operation with substitute value

General notes
Diagnosis of the rail pressure sensor is started as soon as the ignition is switched on. After that, the diagnosis runs continuously every 100 ms.
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