Method and device for detecting an inverted connection of a crankshaft sensor

1. A method for diagnosing an inverted connection of a crankshaft sensor including a toothed wheel rigidly connected to the crankshaft and a magnetic sensing element rigidly connected to a frame, the toothed wheel including teeth regularly spaced at a periphery thereof and a turn marker, the magnetic sensing element configured to detect a presence and/or an absence of matter, the magnetic sensing element disposed in proximity to the periphery of said toothed wheel in order to detect one or more of a presence and an absence of one or more of (i) a tooth of the teeth and (ii) the turn marker, when said toothed wheel moves in front of the magnetic sensing element, the method comprising:

acquiring a signal by the crankshaft sensor, when the crankshaft rotates in a direction during engine start-up,

at each detection of one tooth of the teeth,

determining a tooth time Ti elapsed since a previous tooth detection, and

calculating a ratio Ri of the tooth times according to the formula Ri=(Ti−1) 2 /(Ti*Ti−2), where Ri is the ratio, Ti is the last tooth time, Ti−1 is the penultimate tooth time, and Ti−2 is the tooth time preceding the penultimate tooth time; and

comparing the ratio Ri with a low threshold indicative of the turn marker, and a high threshold indicative of an absence of an inverted connection,

wherein the ratio Ri being between the two thresholds is indicative of the inverted connection.

2. The method as claimed in claim 1 , wherein the low threshold is between 1 and a first value, the low threshold being equal to the maximum of the ratio Ri obtained using a sensor with an inverted connection, and the high threshold is between the first value and a second value, the high threshold being equal to the maximum of the ratio Ri obtained with a correctly-connected sensor.

3. The method as claimed in claim 1 , wherein the ratio Ri being greater than the high threshold is indicative of an absence of inversion.

4. The method as claimed in claim 1 , wherein the ratio Ri being between the low and high thresholds is only indicative of the inverted connection of the crankshaft sensor after a number P max of repetitions.

5. The method as claimed in claim 1 , wherein the ratio Ri being greater than the high threshold is only indicative of an absence of the inverted connection of the crankshaft sensor after a number M max of repetitions.

6. The method as claimed in claim 1 , wherein a tooth detection corresponds to a downward zero crossing of the signal.

7. The method as claimed in claim 1 , wherein a tooth detection corresponds to an upward zero crossing of the signal.

8. The method as claimed in claim 2 , wherein the ratio Ri being greater than the high threshold is indicative of an absence of inversion.

9. The method as claimed in claim 2 , wherein the ratio Ri being between the low and high thresholds is only indicative of the inverted connection of the crankshaft sensor after a number P max of repetitions.

10. The method as claimed in claim 3 , wherein the ratio Ri being between the low and high thresholds is only indicative of the inverted connection of the crankshaft sensor after a number P max of repetitions.

11. The method as claimed in claim 2 , wherein the ratio Ri being greater than the high threshold is only indicative of an absence of the inverted connection of the crankshaft sensor after a number M max of repetitions.

12. The method as claimed in claim 3 , wherein the ratio Ri being greater than the high threshold is only indicative of an absence of the inverted connection of the crankshaft sensor after a number M max of repetitions.

13. The method as claimed in claim 4 , wherein the ratio Ri being greater than the high threshold is only indicative of an absence of the inverted connection of the crankshaft sensor after a number M max of repetitions.

14. The method as claimed in claim 2 , wherein a tooth detection corresponds to a downward zero crossing of the signal.

15. The method as claimed in claim 3 , wherein a tooth detection corresponds to a downward zero crossing of the signal.

16. The method as claimed in claim 2 , wherein a tooth detection corresponds to an upward zero crossing of the signal.

17. The method as claimed in claim 3 , wherein a tooth detection corresponds to an upward zero crossing of the signal.

18. The method as claimed in claim 1 , wherein the ratio Ri being between the low and high thresholds is only indicative of the inverted connection of the crankshaft sensor after a number P max of repetitions equal to 6.

19. The method as claimed in claim 1 , wherein the ratio Ri being greater than the high threshold is only indicative of an absence of the inverted connection of the crankshaft sensor after a number M max of repetitions equal to 10.

20. A device being configured to diagnose the inverted connection of a crankshaft sensor, the device comprising:

at least one computer; and

a crankshaft sensor comprising

a toothed wheel rigidly connected to the crankshaft, the toothed wheel including teeth regularly spaced at the periphery thereof and a turn marker, and

a magnetic sensing element rigidly connected to a frame, the magnetic sensing element configured to detect a presence and/or an absence of matter, the magnetic sensing element in proximity to the periphery of said toothed wheel, in order to detect the presence and/or the absence of a tooth and/or of the turn marker, when said toothed wheel moves in front of the sensing element,

wherein the crankshaft sensor is configured to acquire a signal, when the crankshaft rotates in a direction during engine start-up, and

wherein the computer is configured, at each detection of one tooth of the teeth, to

determine a tooth time Ti elapsed since a previous tooth detection, and

calculate a ratio Ri of the tooth times according to the formula Ri=(Ti−1) 2 /(Ti*Ti−2), where Ri is the ratio, Ti is the last tooth time, Ti−1 is the penultimate tooth time, and Ti−2 is the tooth time preceding the penultimate tooth time,

wherein the computer is configured to compare the ratio Ri with a low threshold indicative of the turn marker, and a high threshold indicative of an absence of an inverted connection, and

wherein the ratio Ri being between the two thresholds is indicative of the inverted connection.