Method for detecting a leak in a tire of a stationary vehicle

1. A method for detecting a leak from a tire of a vehicle, the tire including a member for surveillance of the tire with sensors for measuring pressure and temperature and having a driving operating mode and a stationary operating mode, and the method comprising:

determining that the vehicle is stationary;

then launching the stationary operating mode to detect, when the vehicle is stationary, a presence or an absence of a leak of inflating gas from the tire;

after launching the stationary operating mode of the member, periodically measuring the pressure pg and the temperature θ of the inflating gas in an internal cavity of the tire;

storing a series of pressure and temperature values and measurement times in a non-volatile memory;

converting the measured pressure pg values to absolute pressure P values and the measured temperature θ values to absolute temperature T values and calculating a ratio P/T to obtain a series of values; and

if the series of values decreases by an amount above a given threshold, triggering an alert.

2. The method according to claim 1 , wherein a measurement period is constant and between 30 minutes and 60 minutes inclusive.

3. The method according to claim 1 , wherein a measurement period increases continuously during at least a given number of measurements.

4. The method according to claim 3 , wherein the measurement period increases after each measurement by a factor between 1.5 and 4 inclusive.

5. The method according to claim 3 , wherein the measurement period is constant if it exceeds a given threshold.

6. The method according to claim 1 , wherein the threshold is between 2 and 7% inclusive of the ratio P/T.

7. The method according to claim 1 , wherein the threshold corresponds to a variation between 50 and 200 mbar inclusive of the pressure of the inflating gas from the internal cavity of the tire.

8. The method according to claim 6 , wherein the last measurement or measurements of pressure and of temperature obtained in the driving operating mode of the member are taken as a reference for the ratio P/T.

9. The method according to claim 6 , wherein the last measurement or measurements of pressure and of temperature obtained in the stationary operating mode of the member are taken as a reference for the ratio P/T.

10. The method according to claim 1 , wherein, upon triggering the alert, an alert message is sent to at least one pre-identified addressee.

11. The method according to claim 10 , wherein, the vehicle including a central unit for surveillance of the tires of the vehicle, upon triggering the alert, the member of the tire transmits the alert message to at least one pre-identified recipient via the surveillance central unit.

12. The method according to claim 1 , wherein the vehicle includes a circuit for powering up a dashboard, and wherein determining that the vehicle is stationary is determined when the power up circuit is open.

13. The method according to claim 1 , wherein determining that the vehicle is stationary is determined by virtue of an absence of weight on a seat of a driver.

14. The method according to claim 1 , wherein the member includes an accelerometer for detecting a movement of rotation of the tire, and wherein determining that the vehicle is stationary is determined by an absence of any signal linked to movement in rotation of the tire for a time above a given threshold.

15. The method according to claim 14 , wherein determining that the vehicle is stationary is determined after between 15 and 60 minutes inclusive.

16. The method according to claim 1 , wherein the stationary operating mode switches to the driving operating mode if it is identified that the vehicle is no longer stationary.

17. The method according to claim 1 , wherein the tire includes on at least a part of its interior wall a layer of a self-blocking product.

18. The method according to claim 1 , wherein the vehicle has an autonomous driving mode.