Method and apparatus for detecting a malfunctioning rail pressure sensor

1. A method for detecting a malfunctioning rail pressure sensor, the method comprising:

delivering an analog output signal of the rail pressure sensor characterizing the rail pressure to a control unit;

generating a differential rail pressure signal by the rail pressure sensor as a digital output signal;

delivering the differential rail pressure signal of the rail pressure sensor to the control unit;

analyzing the analog output signal and the differential rail pressure signal in the control unit; and

detecting a malfunctioning rail pressure sensor based on the analysis by the control unit.

2. The method as claimed in claim 1 , further comprising: comparing the transmitted differential rail pressure signal with a predetermined threshold value in the control unit; and

detecting the presence of a malfunctioning rail pressure sensor if the transmitted differential rail pressure signal exceeds the predetermined threshold value.

3. The method as claimed in claim 1 , wherein the rail pressure sensor generates the differential of the output signals of two rail pressure measurement values, each output by a rail pressure measurement device.

4. The method as claimed in claim 3 , wherein the rail pressure sensor generates the differential of the output signals of two rail pressure measurement values detected at the same time.

5. An apparatus for detecting a malfunctioning rail pressure sensor, the apparatus comprising:

a rail pressure sensor; and

a control unit connected to the rail pressure sensor; wherein

the rail pressure sensor comprises a first rail pressure measurement device generating an analog signal and a second rail pressure measurement device generating a digital signal, both signals characterizing the rail pressure; and

the control unit receives and analyzes the analog signal output and the digital signal output;

the rail pressure sensor further comprises a rail pressure differentiator forming a differential rail pressure signal from the output signal of the first rail pressure measurement device and the output signal of the second rail pressure measurement device;

the rail pressure sensor delivers the differential rail pressure signal as a digital signal to the control unit; and

the control unit analyzes the differential rail pressure signal.

6. The apparatus as claimed in claim 5 , wherein that the first and the second rail pressure measurement devices each comprise a measurement transducer.

7. The apparatus as claimed in claim 5 , wherein the first and the second rail pressure measurement devices each comprise an ASIC.

8. The apparatus as claimed in claim 5 , wherein the rail pressure sensor comprises a digital to analog converter connected to the output of the first rail pressure measurement device and providing the analog signal output.

9. The apparatus as claimed in claim 5 , wherein the control unit comprises:

a filter;

an analog to digital converter connected to the output of the filter; and

a computing unit analyzing the received analog signal.

10. The apparatus as claimed in claim 5 , wherein the control unit comprises a computing unit analyzing the differential rail pressure signal.

11. The apparatus as claimed in claim 10 , wherein the computing unit compares the differential rail pressure signal with a predetermined threshold value and detects the presence of a malfunctioning rail pressure sensor if the differential rail pressure signal exceeds the predetermined threshold value.