Granted Patent B2

US 7,181,366 · App. 11/105,055 · Granted Feb 20, 2007

Assignee: GM Global Technologies Operations, Inc.

Abstract

Claims (57)

1. A method for determining the cause of tire pressure change, comprising:

obtaining a first tire pressure (P 1 ) for a first tire temperature (T 1 );

obtaining a measured second tire pressure (P 2 ) for a second tire temperature (T 2 );

calculating an estimated tire pressure (P est ) for the second tire temperature (T 2 );

comparing the estimated tire pressure (P est ) to the measured second tire pressure (T 2 );

and generating, based on the comparing step, a diagnostic message on a display, the diagnostic message indicative of a cause of a pressure change between P 2 and P 1 wherein the diagnostic message indicates a cause selected from the group comprising air loss and temperature.

2. The method of claim 1 , wherein:

if the estimated tire pressure (P est ) is equivalent to the second tire pressure (P 2 ), determining that the pressure change is due to temperature;

if the estimated tire pressure (P est ) is not equivalent to the second tire pressure (P 2 ), determining that the pressure change is due to air loss; and

further comprising communicating the results of the comparison of the estimated tire pressure (P est ) to the second tire pressure (P 2 ).

3. The method of claim 2 , wherein if the estimated tire pressure (P est ) is equivalent to the second tire pressure (P 2 ), the step of communicating the results includes setting the diagnostic message to a “Maintain Tire” message.

4. The method of claim 2 , wherein if the estimated tire pressure (P est ) is not equivalent to the second tire pressure (P 2 ), the step of communicating the results includes setting the diagnostic message to a “Service Tire” message.

5. The method of claim 1 , wherein obtaining a first tire pressure (P 1 ) for the first tire temperature (T 1 ) includes obtaining a placard tire pressure (P 1 ) for a placard temperature (T 1 ).

6. The method of claim 1 , wherein obtaining a first tire pressure (P 1 ) for the first tire temperature (T 1 ) includes a learn procedure providing a learned pressure (P LearnedPressure ) at a learned tire temperature (T LearnedTemp ).

7. The method of claim 6 , wherein the learn procedure is user actuated.

8. The method of claim 6 , wherein the learn procedure takes place automatically based on a detected tire fill event.

9. The method of claim 6 , wherein if the second tire temperature (T 2 ) is greater than the learned tire temperature (T LearnedTemp ) by a designated amount, the method further comprising setting the diagnostic message to a “Tire Overheat” message.

10. The method of claim 6 , further comprising estimating the ambient temperature at which seasonal adjustment will be required (T EstSeasonalAdjTemp ).

11. The method of claim 10 , wherein

T

EstSeasonalAdjTemp

=

T

LearnedTemp

±

(

0.25

)

⁢

(

5.5555556

)

⁢

P

LearnedPressure

6.894757

.

12. The method of claim 1 , wherein P Estimated =P 1 +P Change .

13. The method of claim 12 , wherein P Change =(T 1 −T 2 )·1.24 kPa.

14. A method for determining the cause of tire pressure change from a first tire temperature (T 1 ) to a second tire temperature (T 2 ), comprising:

estimating tire pressure (P est ) for the second tire temperature (T 2 );

measuring a second tire pressure (P 2 ) for the second tire temperature (T 2 );

comparing the estimated tire pressure (P est ) to the second tire pressure (P 2 );

if the estimated tire pressure (P est ) is equivalent to the second tire pressure (P 2 ), indicating on a display that the pressure change is due to temperature;

and if the estimated tire pressure (P est ) is not equivalent to the second tire pressure (P 2 ), indicating, on the display that the pressure change is due to air loss.

15. The method of claim 14 , further comprising communicating the results of the comparison of the estimated tire pressure (P est ) to the second tire pressure (P 2 ).

16. The method of claim 14 , wherein if the pressure change is due to temperature, the method further comprising providing a “Maintain Tire” message.

17. The method of claim 14 , wherein if the pressure change is due to air loss, the method further comprising providing a “Service Tire” message.

18. A tire pressure system, comprising:

a tire pressure sensor associated with at least one tire, the tire pressure sensor capable of measuring a tire pressure of the at least one tire;

a tire temperature sensor associated with the at least one tire, the tire temperature sensor capable of measuring tire temperature of the at least one tire;

processing logic in communication with the tire pressure sensor and the tire temperature sensor, the processing logic capable of estimating and comparing tire pressures at different temperatures for determining a tire pressure change in the at least one tire caused by one of temperature and air loss; and a display in communication with the processing logic, the display capable of communicating the cause of the tire pressure change.

19. The system of claim 18 , further comprising a memory in communication with the control logic, the tire temperature sensor, and the tire pressure sensor, wherein:

the memory is capable of storage and retrieval of a first tire pressure (P 1 ) for the at least one tire received from the tire pressure sensor for a first tire temperature (T 1 ) received from the tire temperature sensor, storing a second tire pressure (P 2 ) for the at least one tire received from the tire pressure sensor for a second tire temperature (T 2 ) received from the tire temperature sensor; and wherein;

the control logic is capable estimating a tire pressure (P est ) at (T 2 ) for the at least one tire, and capable of determining one of:

the pressure change is caused by temperature (P est ) is equivalent to (P 2 ), and

the pressure change is caused by air loss if the estimated tire pressure (P est ) is not equivalent to (P 2 ).

Assignments (12)

Continuity (1)