Method for assessing the range of a run-flat system

• US 6,672,149 B2
• Filed: 01/23/2003
• Issued: 01/06/2004
• Est. Priority Date: 07/25/2000
• Status: Expired due to Fees

• Current Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Original Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Hottebart, Francois, Shepherd, Russell
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): ALLEN, ANDRE J
• Application Number:
  US10/350,259
• Publication Number:
  US 20030140687A1
• Time in Patent Office: 348 Days
• Field of Search: 731/46, 731/462, 731/463, 731/464, 731/465, 731/468, 152/158, 152/454, 152/517, 152/209, 152/154.2
• US Class Current: 73/146
• CPC Class Codes: B60C 23/02 Signalling devices actuated by tyre pressure hand-held tyre pressure gauges G01L17/00
• CPC Class Codes: B60C 23/0401 characterised by the type of alarm
• CPC Class Codes: Y10T 152/10027 with wear indicating feature

Abstract

The invention concerns a method for assessing the range of a motor vehicle run-flat system comprising at least for each wheel a tire casing, a deflation alarm and means supporting the running tread of the tire casing when the casing is deflated, which method, from the instant the deflation alarm has detected a predetermined deflating threshold, includes the steps of: periodically measuring the distance covered and a parameter C(t) characteristic of the running conditions; determining on the basis of C(t) and the measured distance over Δt a quantity characteristic of potential elementary damage of the system during the elapsed time Δt; calculating an estimate of the global damage by combining the calculated elementary damage levels since the start of flat running; and transmitting to the vehicle driver a quantity related to that estimate of the flat running system global damage.

Claims

1. A method for assessing the range of a run-flat system which is fitted to a vehicle, the system comprising, at least for each wheel, a tire, a deflation alarm and means for supporting the tread of the tire in the event that the tire is deflated, wherein upon detecting an inflation pressure in a tire below a predetermined threshold, the method comprising the steps of:

measuring periodically a distance travelled and a parameter C(t) characteristic of the travel conditions;

determining as a function of C(t) and the distance travelled over the period Δ

t, a quantity characteristic of a potential elementary damage to the system over the said elapsed period Δ

t;

calculating an estimate of the overall damage from a combination of the potential elementary damage determined since the start of run flat travelling; and

transmitting to the driver of the vehicle a quantity linked to this estimate of overall damage to the run flat.

2. A method according to claim 1, further comprising determining a function F(C) from a series of rolling tests in conditions corresponding to those of the characteristic parameter C giving an estimate e for any value of the parameter C of the range of the new run flat system in travel conditions C:

3. A method according to claim 2, wherein a potential elementary damage Δ

J over the period of travel Δ

t is estimated from a ratio;

4. A method according to claim 3, wherein a quantity J indicates the potential for using the run flat system at any period of measurement Δ

t, and wherein the estimate of J(t) is updated as;

5. A method according to claim 4, wherein J is set to 1 when the run flat system is new.

6. A method according to claim 4, wherein the updated value of J(t) is transmitted to the driver of the vehicle.

7. A method according to claim 4, further comprising determining a quantity E as the remaining range of the run flat system under current conditions of travel, and wherein a current value of E is transmitted to the driver of the vehicle.

8. A method according to claim 7, wherein E is estimated as:

9. A method according to claim 4, wherein when a given threshold J₀ is passed, the method further comprises transmitting a warning to the driver of the vehicle.

10. A method according to claim 1, wherein, when the measured pressure of inflation is below a given threshold, the tire concerned is considered to be in the run flat condition.

11. A method according to claim 1, further comprising the steps of measuring periodically the temperature of the inside air T, and using the temperature of the inside air as a parameter characteristic of the conditions of travel of the run flat system.

12. A method according to claim 11, further comprising calculating a value e(t)=F[T(t)] as:

$e<br><br>\left(t\right)=e_0<br><br>\exp <br><br>\left[\left(\ln <br><br>\text{\hspace{1em}<br><br>}<br><br>2\right)<br><br>\left(\frac{T_0-T<br><br>\left(t\right)}{\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>T}\right)\right]$

where;

e is the said modelled range expressed in kilometres, which corresponds to the available range before breakdown of a travelling run flat system travelling at a constant temperature T;

T is the temperature of the inside air (in degrees Celsius);

T₀ is an arbitrary reference temperature (in degrees Celsius);

e₀ is the estimated range at temperature T₀;

Δ

T (in degrees Celsius) is a difference in temperature corresponding to a reduction in the range by a factor of 2.

13. A method according to claim 11, further comprising calculating a value e(t)=F[T(t)] as:

14. A method according to claim 13, in which a maximum value of e is limited to an arbitrary given value.

15. A method according to claim 1, further comprising using an inflation pressure of the tire concerned as a complementary characteristic parameter of the conditions of travel of the run flat system.

16. A method according to claim 1, further comprising using a location on the vehicle of the tire concerned as a complementary characteristic parameter of the conditions of travel of the run flat system.

17. A method according to claim 1, wherein the vehicle includes means for estimating the load applied to the wheels, the method further comprising using the load applied to the wheel concerned as a complementary characteristic parameter of the conditions of travel of the run flat system.

18. A method according to claim 1, wherein the vehicle includes means for measuring the temperature outside the vehicle, the method further comprising using the outside temperature as a complementary characteristic parameter of the conditions of travel of the run flat system.

19. A method according to claim 1, further comprising using a speed of travel of the vehicle as a complementary characteristic parameter of the conditions of travel of the run flat system.

20. A method according to claim 1, wherein the vehicle includes means for measuring the transverse forces applied to the wheels, the method further comprising using transverse forces applied to the wheels as a complementary characteristic parameter of the conditions of travel of the run flat system.

21. A method according to claim 1, further comprising using at least one of the speed of motion of the windshield wipers, the type of vehicle, and the longitudinal forces as a complementary characteristic parameter of the conditions of travel of the run flat system.

22. A method according to claim 1, further comprising using at least one of the air temperature inside the other tires on the vehicle and the pressure of the other tires on the vehicle as a complementary characteristic parameter of the conditions of travel of the run flat system.

23. A method according to claim 1, wherein the means of structural reinforcement of the tire comprises a bearing disposed radially outside relative to the rim of the wheel to support the tread of the said tire in the event of loss of pressure of inflation.

24. A method according to claim 1, wherein the means of structural reinforcement of the tire comprises reinforcement inserted into the structure of the said tire.

25. The method according to claim 1, further comprising the step of evaluating a re-use potential of the tire implicated by travel in the flat condition.

26. The method according to claim 1, further comprising the step of evaluating a re-use potential of the safety insert of the tire implicated by travel in the flat condition.