Method and device for detecting decompression of tires, and program for judging decompression of tires

• US 20050087008A1
• Filed: 10/20/2004
• Published: 04/28/2005
• Est. Priority Date: 10/27/2003
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Yanase, Minao
• Granted Patent: US 7,136,775 B2
• Time in Patent Office: Days
• US Class Current: 73/146
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00

Abstract

A detection method of reducing the air pressure of tires based on the rotational speed of wheels mounted on a vehicle. The method includes steps of: determining the rotational speed of said each wheel, memorizing the rotational speed of said wheel, determining the loading sensitivity of the dynamic load radius of tires caused by movement of a load during turning, comparing said loading sensitivity with the loading sensitivity of the dynamic load radii of tires at initialization which are preliminarily memorized, and judging decompression of tires based on the result of said comparison. Further, a loading sensitivity-calculating method of determining the loading sensitivity of the dynamic load radii of tires includes steps of: determining an lateral acceleration during turning of a vehicle, determining the shift rate of a judgment value which is the relative comparison of rotational speed of wheels on a pair of diagonals of a vehicle, and determining the loading sensitivity, by dividing said shift rate by an lateral acceleration by every vehicle speed region.

Claims

1. A method for detecting decompression of tires based on rotational speed of wheels mounted on a vehicle, comprising the steps of:

determining rotational speeds of said wheels;

memorizing the rotational speeds of said wheels;

determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle;

comparing the loading sensitivity of dynamic load radii of said tires caused by movement of a load during said turning with predetermined loading sensitivity of dynamic load radii of said tires during normal air pressure; and

judging decompression of said tires based on a result of said comparison.

2. The method for detecting decompression of tires of claim 1 further comprising a steps of determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle by calculating a relation equation between lateral acceleration of said vehicle and a relative comparison between sums of said wheel rotational speeds on a pair of diagonals of said vehicle.

7. The method for detecting decompression of tires of claim 1 further comprising the steps of:

comparing the loading sensitivity of the dynamic load radii of tires caused by movement of a load during turning of said vehicle with predetermined loading sensitivities of the dynamic load radii of various tires; and

judging reduction of air pressure of tires based on the result of said comparison, including the steps of;

deducing reduced pressure sensitivity of the dynamic load radii of said tires based on the result of said comparison, and

judging reduction of air pressure of said tires based on a result of said deduction.

8. The method for detecting decompression of tires of claim 7 further comprising a steps of determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle by calculating a relation equation between lateral acceleration of said vehicle and a relative comparison between sums of said wheel rotational speeds on a pair of diagonals of said vehicle.

9. The detection method of reducing the air pressure of tires of claim 7 or 8, further comprising a step of changing a threshold for judging decompression of said tires by said reduced pressure sensitivity.

25. The method for detecting decompression of tires of claim 1, 2, 7 or 8 further comprising a step of determining the loading sensitivity of the dynamic load radii of tires by a loading sensitivity-calculating method of claim 16.

26. The method for detecting decompression of tires of claim 1, 2, 7 or 8 further comprising a step of determining the loading sensitivity of the dynamic load radii of tires by a loading sensitivity-calculating method of claim 17.

27. The method for detecting decompression of tires of claim 1, 2, 7 or 8 further comprising a step of determining the loading sensitivity of the dynamic load radii of tires by a loading sensitivity-calculating method of claim 18.

3. A device for detecting decompression of tires based on rotational speed of wheels mounted on a vehicle, comprising:

a rotational speed-detecting means for determining rotational speeds of said wheels;

a memory means for memorizing the rotational speeds of said wheels;

a sensitivity-calculating means for determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle;

a sensitivity-comparing means for comparing the loading sensitivity of dynamic load radii of said tires caused by movement of a load during said turning with predetermined loading sensitivity of dynamic load radii of said tires during normal air pressure; and

a judgment means for judging reduction of air pressure of tires based on a result of said comparison.

4. The device for detecting decompression of tires of claim 3 further comprising a sensitivity-calculating means for determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle by calculating a relation equation between lateral acceleration of said vehicle and a relative comparison between sums of said wheel rotational speeds on a pair of diagonals of said vehicle.

10. A device for detecting decompression of tires of claim 3 further comprising:

a sensitivity-comparing means for comparing the loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle with predetermined loading sensitivities of dynamic load radii of various tires; and

a judgment means for judging decompression of tires based on the result of said comparison, including;

a sensitivity-deducing means for deducing reduced pressure sensitivity of dynamic load radii of said tires based on the result of said comparison; and

a judgment means for judging decompression of tires based on the result of said deduction.

11. The device for detecting decompression of tires of claim 10 further comprising a sensitivity-calculating means for determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle by calculating a relation equation between lateral acceleration of said vehicle and a relative comparison between sums of said wheel rotational speeds on a pair of diagonals of said vehicle.

12. The device for detecting decompression of tires of claim 10 or 11, further comprising a threshold-changing means for changing a threshold for judging decompression of said tires by said reduced pressure sensitivity.

28. The device for detecting decompression of tires of claim 3, 4, 10 or 11 further comprising means for determining the loading sensitivity of the dynamic load radii of tires, including a loading sensitivity-calculating device of claim 19.

29. The device for detecting decompression of tires of claim 3, 4, 10 or 11 further comprising means for determining the loading sensitivity of the dynamic load radii of tires, including a loading sensitivity-calculating device of claim 20.

30. The device for detecting decompression of tires of claim 3, 4, 10 or 11 further comprising means for determining the loading sensitivity of the dynamic load radii of tires, including a loading sensitivity-calculating device of claim 21.

5. A program for judging decompression of tires based on rotational speed of wheels mounted on a vehicle, comprising:

means for memorizing rotational speeds of said wheels;

means for determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle;

means for comparing the loading sensitivity of dynamic load radii of said tires caused by movement of a load during said turning with loading sensitivity of dynamic load radii of said tires during normal air pressure; and

means for judging decompression of said tires based on a result of said comparison.

6. The program for judging decompression of tires of claim 5 further comprising means for determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle by calculating a relation equation between lateral acceleration of said vehicle and a relative comparison between sums of said wheel rotational speeds on a pair of diagonals of said vehicle.

13. The program for judging decompression of tires of claim 5 further comprising:

means for comparing the loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle with predetermined loading sensitivities of dynamic load radii of various tires; and

means for judging decompression of tires based on the result of said comparison, including;

means for deducing reduced pressure sensitivity of dynamic load radii of said tires based on a result of said comparison; and

means for judging decompression of tires based on the result of said deduction.

14. The program for judging decompression of tires of claim 13 further comprising means for determining loading sensitivity of dynamic load radii of said tires caused by movement of a load during turning of said vehicle by calculating a relation equation between lateral acceleration of said vehicle and a relative comparison between sums of said wheel rotational speeds on a pair of diagonals of said vehicle.

15. The program for judging decompression of tires of claim 13 or 14, further comprising means for changing a threshold for judging decompression of said tires by said reduced pressure sensitivity.

31. The program for judging decompression of tires of claim 5, 6, 13 or 14 further comprising means for determining the loading sensitivity of the dynamic load radii of tires, including a program for calculating loading sensitivity of tires of claim 22.

32. The program for judging decompression of tires of claim 5, 6, 13 or 14 further comprising means for determining the loading sensitivity of the dynamic load radii of tires, including a program for calculating loading sensitivity of tires of claim 23.

33. The program for judging decompression of tires of claim 5, 6, 13 or 14 further comprising means for determining the loading sensitivity of the dynamic load radii of tires, including a program for calculating loading sensitivity of tires of claim 24.

16. A loading sensitivity-calculating method for determining loading sensitivity of dynamic load radii by loading fluctuation of tires, comprising the steps of:

determining lateral acceleration of a vehicle during turning of said vehicle;

determining a shift rate of a judgment value calculated by relative comparison between sums of said wheel rotational speeds on a pair of diagonals of said vehicle during turning of the vehicle; and

determining loading sensitivity obtained by dividing said shift rate by lateral acceleration at every vehicle speed region.

17. The loading sensitivity-calculating method of claim 16 further comprising a step of determining a shift rate of a judgment value including the steps of:

determining a yaw rate of said vehicle;

determining reciprocal of a turning radius obtained from wheel rotational speed of said vehicle and reciprocal of a turning radius obtained from said yaw rate; and

determining a value corresponding to said shift rate calculated by a difference between the reciprocal of a turning radius obtained from said wheel rotational speed and the reciprocal of a turning radius obtained from said yaw rate.

18. The loading sensitivity-calculating method of claim 16 further comprising a step of determining a shift rate of a judgment value including the steps of:

determining reciprocal of a turning radius obtained from wheel rotational speed of said vehicle and reciprocal of a turning radius obtained from lateral acceleration of said vehicle; and

determining a value corresponding to said shift rate calculated by a difference between the reciprocal of a turning radius obtained from said wheel rotational speed and the reciprocal of a turning radius obtained from said lateral acceleration.

19. A loading sensitivity-calculating device for determining the loading sensitivity of dynamic load radii by loading fluctuation of tires, comprising:

a lateral acceleration-calculation means for determining lateral acceleration of a vehicle during turning of said vehicle;

a shift rate-calculating means for determining a shift rate of a judgment value calculated by relative comparison of sums of said wheel rotational speeds on a pair of diagonals of said vehicle; and

a loading sensitivity-calculating means for determining loading sensitivity obtained by dividing said shift rate by said lateral acceleration at every vehicle speed region.

20. The loading sensitivity-calculating device of claim 19 further comprising means for determining a shift rate of a judgment value including:

means for determining a yaw rate of said vehicle;

means for determining reciprocal of a turning radius obtained from wheel rotational speed of said vehicle and reciprocal of a turning radius obtained from said yaw rate; and

means for determining a value corresponding to said shift rate calculated by a difference between the reciprocal of a turning radius obtained from said wheel rotational speed and the reciprocal of a turning radius obtained from said yaw rate.

21. The loading sensitivity-calculating device of claim 19 further comprising means for determining a shift rate of a judgment value including:

means for determining the reciprocal of a turning radius obtained from wheel rotational speed of said vehicle and reciprocal of a turning radius obtained from said lateral acceleration; and

means for determining a value corresponding to said shift rate calculated by a difference between the reciprocal of a turning radius obtained from said wheel rotational speed and the reciprocal of a turning radius obtained from said lateral acceleration.

22. A program for calculating loading sensitivity of tires comprising:

means for determining lateral acceleration of a vehicle during turning of said vehicle;

means for determining a shift rate of a judgment value calculated by relative comparison of sums of said wheel rotational speeds on a pair of diagonals of said vehicle; and

means of determining loading sensitivity obtained by dividing said shift rate by said lateral acceleration at every vehicle speed region.

23. The program for calculating loading sensitivity of tires of claim 22 further comprising means for determining a shift rate of a judgment value including:

means for determining a yaw rate of said vehicle;

means for determining reciprocal of a turning radius obtained from wheel rotational speed of said vehicle and reciprocal of a turning radius obtained from said yaw rate; and

means for determining a value corresponding to said shift rate calculated by a difference between the reciprocal of a turning radius obtained from said wheel rotational speed and the reciprocal of a turning radius obtained from said yaw rate.

24. The program for calculating loading sensitivity of tires of claim 22 further comprising means for determining a shift rate of a judgment value including:

means for determining the reciprocal of a turning radius obtained from wheel rotational speed of said vehicle and reciprocal of a turning radius obtained from said lateral acceleration; and

means for determining a value corresponding to said shift rate calculated by a difference between the reciprocal of a turning radius obtained from said wheel rotational speed and the reciprocal of a turning radius obtained from said lateral acceleration.