PIEZOELECTRIC BASED SYSTEM AND METHOD FOR DETERMINING TIRE LOAD

• US 20130278406A1
• Filed: 12/30/2010
• Published: 10/24/2013
• Est. Priority Date: 12/30/2010
• Status: Active Grant

• Current Assignee: Compagnie générale des établissements Michelin
• Original Assignee: Compagnie générale des établissements Michelin, Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Weston, David Alan
• Granted Patent: US 10,000,100 B2
• Time in Patent Office: Days
• US Class Current: 340/442
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: B60C 23/0488 Movement sensor, e.g. for sensing angular speed, acceleration or centripetal force
• CPC Class Codes: B60C 23/0489 for detecting the actual angular position of the monitoring device while the wheel is turning
• CPC Class Codes: B60C 23/0493 for attachment on the tyre
• CPC Class Codes: B60C 23/064 comprising tyre mounted deformation sensors, e.g. to determine road contact area

Abstract

Systems and methods of determining tire load from measured tire parameters include using a piezoelectric based sensor to obtain one or more contact patch parameters (e.g., contact patch entry time, contact patch exit time total contact patch time and contact patch angle) and one or more additional sensors to obtain tire pressure. Selected contact patch parameter measurements and pressure values are then compared with known combinations of contact patch parameter values and pressure values stored in a look-up table. A corresponding determined tire load value is then provided as electronic output.

Claims

1. A method of electronically determining tire load, comprising:

determining tire pressure within a tire;

determining one or more contact patch parameters related to the tire'"'"'s operation within a contact patch area adjacent to a ground surface by analyzing the output of a piezoelectric sensor provided with the tire;

electronically comparing the determined tire pressure and the one or more contact patch parameters to a database of known values to determine a corresponding tire load value for the tire; and

providing the determined corresponding tire load value for the tire as electronic output.

2. The method of claim 1, wherein the one or more contact patch parameters comprise a plurality of contact patch parameters respectively associated with a plurality of piezoelectric elements provided within the piezoelectric sensor.

3. The method of claim 1, wherein said one or more contact patch parameters comprises one or more of a contact patch entry time, contact patch exit time, total contact patch time and contact patch angle.

4. The method of claim 3, wherein said one or more contact patch parameters are determined by identifying maximum and minimum values of the first derivative of the raw signal obtained from the piezoelectric sensor.

5. The method of claim 3, wherein said one or more contact patch parameters are determined by identifying zero crossings of the second derivative of the raw signal obtained from the piezoelectric sensor.

6. The method of claim 1, wherein said one or more contact patch parameters comprises a contact patch angle indicative of the angular portion of a tire that is in contact with the ground surface during operation.

7. The method of claim 6, wherein said contact patch angle for a given iteration of the piezoelectric sensor traveling through the tire'"'"'s contact patch is determined by subtracting the contact patch exit time from the contact patch entry time to obtain a first difference;

obtaining a second difference by measuring the amount of time for one revolution of a tire; and

dividing the first difference by the second difference.

8. The method of claim 1, wherein the tire pressure is determined using an absolute pressure gauge.

9. The method of claim 1, wherein determining tire pressure comprises determining absolute tire pressure by measuring both pressure and temperature within a tire.

10. The method of claim 1, further comprising a step of transmitting the tire pressure and the one or more contact patch parameters to a location remote from the tire.

11. The method of claim 1, further comprising a step of providing operational power for various electronic components within the tire from a separate piezoelectric element than the piezoelectric sensor.

12. A piezoelectric system for determining tire load within a tire, comprising:

a sensor configured to measure tire pressure;

one or more piezoelectric elements configured to generate one or more respective electric signals indicative of tire deformation at entry into and exit from a contact patch area present within the tire when the tire is rolling along a ground surface and supporting a load;

a first microprocessor for receiving the electric signal output from said one or more piezoelectric elements and determining one or more contact patch parameters;

a memory for storing a look-up table correlating known combinations of tire pressure and contact patch parameters to tire load values such that an electronic comparison can be made of the tire pressure and the one or more contact patch parameters to the look-up table stored in memory to determine a corresponding tire load value; and

an output device for relaying the determined corresponding tire load value as electronic output.

13. The piezoelectric system of claim 12, wherein said one or more piezoelectric elements comprise a plurality of piezoelectric elements that are provided on a common substantially planar surface and are mounted laterally across the interior surface of a tire beneath the tire crown;

14. The piezoelectric system of claim 12, further comprising an additional piezoelectric element used for generating power for selected electronic components within the piezoelectric system such that none of the one or more piezoelectric elements configured to generate one or more respective electric signals indicative of tire deformation is used for power generation within the tire.

15. The piezoelectric system of claim 14, wherein said plurality of piezoelectric elements are configured in a linear array with selected piezoelectric elements aligned relative to selected tread features of a tire.

16. The piezoelectric system of claim 12, wherein said system comprises an in-tire module containing said sensor configured to measure tire pressure and said one or more piezoelectric elements.

17. The piezoelectric system of claim 16, wherein said in-tire module also contains said first microprocessor and a wireless transceiver.

18. The piezoelectric system of claim 16, wherein said system comprises a vehicle on-board system configured to wirelessly receive the tire pressure and the one or more contact patch parameters for a plurality of tires within a vehicle.

19. The piezoelectric system of claim 18, wherein said vehicle on-board system comprises said memory for storing a look-up table and a second microprocessor communicatively coupled to said memory and configured to implement the electronic comparison of tire pressure and the one or more contact patch parameters to the look-up table stored in memory to determine a corresponding tire load value.

20. The piezoelectric system of claim 12, wherein said one or more contact patch parameters comprises an interpolation of data points obtained across a plurality of piezoelectric elements.

21. The piezoelectric system of claim 12, wherein said one or more contact patch parameters comprises one or more of a contact patch entry time, contact patch exit time, total contact patch time and contact patch angle for each of said one or more piezoelectric elements.