METHOD FOR DETECTING A WIRING FAULT IN A CAPACITIVE SENSOR

• US 20160097799A1
• Filed: 10/01/2015
• Published: 04/07/2016
• Est. Priority Date: 10/01/2014
• Status: Active Grant

• Current Assignee: Vitesco Technologies GmbH (Continental AG)
• Original Assignee: Continental Automotive France (Continental AG), Continental Automotive GmbH (Continental AG)
• Inventors: ROCHER, Jacques
• Granted Patent: US 9,835,667 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01L 27/002 Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination
• CPC Class Codes: G01L 27/007 Malfunction diagnosis, i.e. diagnosing a sensor defect
• CPC Class Codes: G01R 31/50 Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections testing of sparking plugs H01T13/58

Abstract

A method for detecting a wiring fault in a capacitive sensor (1), such as a knock sensor, connected, via a passive acquisition interface (5), to a communication port (P1), that can be configured in either input mode or output mode, of a computer (2), wherein the communication port (P1) is configured in output mode, and a square wave voltage Vn capable of at least partially charging the capacitors (C6, C7, C8a, C8b, C10) of the acquisition interface (5) and the capacitive sensor (1) is generated during a time interval Tc, after which the communication port is switched to its input mode, so that at least one data element representative of the voltage of the capacitors and of the capacitive sensor is acquired, and finally these data are compared with previously stored reference data so that a wiring fault can be deduced if there is no matching between the data.

Claims

1. A method for detecting a wiring fault in a capacitive sensor (1), such as a knock sensor, connected, via a passive acquisition interface (5) comprising capacitors (C6, C7, C8a, C8b, C10), to a communication port (P1), that can be configured in either input mode or output mode, of a computer (2), wherein:

in a preliminary calibration step, a square wave voltage Vn capable of at least partially charging the capacitors (C6, C7, C8a, C8b, C10) of said acquisition interface and the capacitive sensor 1 is delivered to the acquisition interface (5) during a charging time Tc, after which at least one data element, called the reference data element, is acquired and stored, this data element being representative, after at least one time interval tm≧

0 following the interruption of the square wave voltage, of the voltage of said capacitors and capacitive sensor in the absence of a wiring fault,

and procedures for detecting wiring faults are followed, these procedures consisting in;

configuring the communication port (P1) in output mode and generating a square wave voltage Vn during a charging time Tc,

switching the communication port (P1) to its input mode at the end of the charging time Tc, and acquiring at least one data element, called the measured data element, which is representative, after each time interval tm≧

0 following the interruption of the square wave voltage, of the voltage of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1),

and comparing each measured data element with the corresponding reference data element, so that a wiring fault in the capacitive sensor (1) can be deduced if said data elements do not coincide.

2. The detection method as claimed in claim 1, wherein the reference and measurement data are acquired at the time of the interruption of the square wave voltage, for the purpose of comparing the reference and measurement data representative of the charging voltage of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1) after the generation of said square wave voltage.

3. The detection method as claimed in claim 1, wherein the reference and measurement data are acquired after a time interval tm>

0 following the interruption of the square wave voltage, for the purpose of comparing the reference and measurement data representative of the discharge voltage of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1).

4. The detection method as claimed in claim 3, wherein a data element representative of the voltage time constant is acquired during the discharging of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1).

5. The detection method as claimed in claim 1, wherein in the preliminary step, reference data representative of the voltage of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1) are also acquired and stored for different types of wiring faults, so that said wiring faults can be distinguished.

6. The method as claimed in claim 1, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.

7. The method as claimed in claim 1, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein a square wave voltage Vn is generated, either simultaneously or with a time lag, during charging times Tc1 and Tc2 respectively, on each of the two communication ports (P1, P2), and the data representative of the voltage of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1) respectively are acquired, for each of said communication ports, at the ends of the charging times Tc1 and Tc2 respectively.

8. The detection method as claimed in claim 2, wherein in the preliminary step, reference data representative of the voltage of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1) are also acquired and stored for different types of wiring faults, so that said wiring faults can be distinguished.

9. The detection method as claimed in claim 3, wherein in the preliminary step, reference data representative of the voltage of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1) are also acquired and stored for different types of wiring faults, so that said wiring faults can be distinguished.

10. The detection method as claimed in claim 4, wherein in the preliminary step, reference data representative of the voltage of the capacitors (C6, C7, C8a, C8b, C10) and of the capacitive sensor (1) are also acquired and stored for different types of wiring faults, so that said wiring faults can be distinguished.

11. The method as claimed in claim 2, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.

12. The method as claimed in claim 3, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.

13. The method as claimed in claim 4, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.

14. The method as claimed in claim 5, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.

15. The method as claimed in claim 2, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.

16. The method as claimed in claim 3, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.

17. The method as claimed in claim 4, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.

18. The method as claimed in claim 5, for detecting wiring faults in a capacitive sensor (1) wired in differential mode by means of an acquisition interface (5) having two branches (6, 7), each connecting one terminal (1a, 1b) of said capacitive sensor to a communication port (P1, P2), wherein each detection procedure is divided into two successive steps, namely a first step in which a square wave voltage Vn is generated on one of the communication ports (P1), while the other communication port (P2) is grounded, and a second step in which the functions of the two communication ports (P1, P2) are reversed.