TIRE AIR PRESSURE OPTIMIZATION SYSTEM FOR IMPROVING TREAD WEAR

• US 20150239303A1
• Filed: 05/13/2015
• Published: 08/27/2015
• Est. Priority Date: 09/30/2010
• 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: Clayton, William Bennett, McKibben, Dave Michael, Merrill, Zachary Alexander, Williamson, Lawrence Otis, Yount, Wayne Carl
• Granted Patent: US 9,555,673 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60C 23/002 by monitoring conditions other than tyre pressure or deformation
• CPC Class Codes: G01L 17/00 Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies

Abstract

A system is provided for automatically adjusting the air pressure of a tire based on variations in loading to improve tread wear. For a particular loading of the tire, the system provides for the determination of a preferred air pressure setting designed to minimize tread wear. This preferred air pressure, P_p, is determined from an analysis of the longitudinal stresses that occur within the contact patch of the tread.

Claims

1. A method for regulating air pressure of a tire on a vehicle, the tire having shoulders, a tread with a ground contacting portion, and defining lateral and longitudinal directions, the lateral direction being parallel to an axis of rotation of the tire, the longitudinal direction being perpendicular to the axis of rotation of the tire, the method comprising:

ascertaining an actual or anticipated tire load L_a on the tire;

selecting, from a correlation of preferred air pressures P_p for a range of multiple tire loads L_i on the tire, a preferred air pressure P_p for the actual or anticipated load L_a on the tire; and

adjusting the air pressure of the tire while on the vehicle to the preferred air pressure P_p for the actual or anticipated tire load L_a;

wherein the correlation of preferred air pressures P_p is based on average longitudinal stress σ

_x-avg in the tread at one or more loads L_i over the range of multiple loads L_i.

2. The method for regulating air pressure of a tire on a vehicle in claim 1, wherein adjusting the air pressure of the tire comprises increasing the air pressure, decreasing the air pressure, or both.

3. The method for regulating air pressure of a tire on a vehicle as in claim 1, wherein ascertaining the actual load comprises measuring a load carried by the vehicle.

4. The method for regulating air pressure of a tire on a vehicle as in claim 1, wherein the range of multiple tire loads L_i is defined as the loads between about a minimum operating load of the tire to about a maximum sidewall load of the tire.

5. The method for regulating air pressure of a tire on a vehicle as in claim 1, further comprising measuring the air pressure of the tire on the vehicle before the adjusting.

6. The method for regulating air pressure of a tire on a vehicle as in claim 1, wherein the tire is a non-ribbed tire.

7. The method for regulating air pressure of a tire on a vehicle as in claim 1, wherein determination of the correlation of preferred air pressures P_p comprises:

dividing the tread of the tire into multiple zones along the lateral direction, the multiple zones including a shoulder zone along each shoulder of the tire and one or more intermediate zones between the shoulder zones;

selecting a range of tire air pressures;

determining, for a load L_i in the range of multiple tire loads L_i, the average longitudinal stress σ

_x in each of the zones over the selected range of tire air pressures;

identifying, from the selected range of tire air pressures, the preferred air pressure P_p for the load L_i, wherein the preferred air pressure P_p is the pressure at which both i) the average longitudinal stress σ

_x-avg for all of the zones is minimized and ii) the average longitudinal stress σ

_x-avg for each of the intermediate zones is maintained at or above a predetermined threshold longitudinal stress σ

_x-th ; and

repeating, over the range of multiple tire loads L_i, the determining and identifying so as to provide the correlation of the preferred air pressures P_p.

8. The method for regulating air pressure of a tire on a vehicle as in claim 7, wherein the identifying comprises, for the load L_i:

eliminating from the selected range of air pressures all pressures at which the average longitudinal stress σ

_x-avg for any zone is less than the predetermined threshold longitudinal stress σ

_x-th and, if there is no pressure at which the average longitudinal stress σ

_x-avg for any zone is less than the threshold longitudinal stress σ

_x-th, then eliminating from the selected range of air pressures all pressures at which the average longitudinal stress σ

_x-avg for either of the shoulder zones is less than the threshold longitudinal stress σ

_x-th;

calculating S, the sum of the squares of the average longitudinal stress σ

_x-avg, of each of the zones, for each of the pressures remaining in the selected range of air pressures after the eliminating; and

selecting, from the pressures remaining in the selected range of air pressures after the eliminating, the preferred air pressure P_p as the greater of either a) the air pressure having the smallest value of S or b) the air pressure P_min that is the minimum recommended for the load L_i.

9. A system for adjustment of tire air pressure on a vehicle, comprising:

equipment for measuring the pressure of at least one tire on the vehicle;

equipment for adjusting the pressure of at least one tire on the vehicle; and

a controller configured for

ascertaining an actual or anticipated tire load L_a on the tire;

selecting, from a correlation of preferred air pressures P_p for a range of multiple tire loads L_i on the tire, a preferred air pressure P_p for the actual or anticipated load L_a on the tire; and

adjusting the air pressure of the tire while on the vehicle to the preferred air pressure P_p for the actual or anticipated tire load L_a;

wherein the correlation of preferred air pressures P_p is based on average longitudinal stress σ

_x-avg in the tread at one or more loads L_i over the range of multiple loads L_i.

10. The system for adjustment of tire air pressure on a vehicle as in claim 9, wherein the determination of the correlation of preferred air pressures P_p comprises:

dividing the tread of the tire into multiple zones along the lateral direction, the multiple zones including a shoulder zone along each shoulder of the tire and one or more intermediate zones between the shoulder zones;

selecting a range of tire air pressures;

determining, for a load L_i in the range of multiple tire loads L_i, the average longitudinal stress σ

_x in each of the zones over the selected range of tire air pressures;

identifying, from the selected range of tire air pressures, the preferred air pressure P_p for the load L_i, wherein the preferred air pressure P_p is the pressure at which both i) the average longitudinal stress σ

_x-avg for all of the zones is minimized and ii) the average longitudinal stress σ

_x-avg for each of the intermediate zones is maintained at or above a predetermined threshold longitudinal stress σ

_x-th; and

repeating, over the range of multiple tire loads L_i, the determining and identifying so as to provide the correlation of the preferred air pressures P_p.

11. The system for adjustment of tire air pressure on a vehicle as in claim 9, wherein the identifying comprises, for the load L_i:

eliminating from the selected range of air pressures all pressures at which the average longitudinal stress σ

_x-avg for any zone is less than the predetermined threshold longitudinal stress σ

_x-th and, if there is no pressure at which the average longitudinal stress σ

_x-avg for any zone is less than the threshold longitudinal stress σ

_x-th, then eliminating from the selected range of air pressures all pressures at which the average longitudinal stress σ

_x-avg for either of the shoulder zones is less than the threshold longitudinal stress σ

_x-th;

calculating S, the sum of the squares of the average longitudinal stress σ

_x-avg, of each of the zones, for each of the pressures remaining in the selected range of air pressures after the eliminating; and

selecting, from the pressures remaining in the selected range of air pressures after the eliminating, the preferred air pressure P_p as the greater of either a) the air pressure having the smallest value of S or b) the air pressure P_min that is the minimum recommended for the load L_i.