Method and device for monitoring the instantaneous behaviour of a tyre during the running of a motor vehicle

• US 20020166373A1
• Filed: 05/10/2002
• Published: 11/14/2002
• Est. Priority Date: 11/18/1999
• Status: Active Grant

• Current Assignee: Pirelli Pneumatici S.P.A. (Pirelli & C SPA)
• Original Assignee: Pirelli Pneumatici S.P.A. (Pirelli & C SPA)
• Inventors: Mancosu, Federico, Matrascia, Giuseppe, Misani, Piero, Gelosa, Elda
• Granted Patent: US 6,561,018 B2
• Time in Patent Office: Days
• US Class Current: 73/146
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/1725 Using tyre sensors, e.g. Sidewall Torsion sensors [SWT] for tyre pressure and temperature detection B60C23/00

Abstract

A method for monitoring the instantaneous behavior of a tire includes the steps of acquiring and storing at least one basic reference curve representing variation of a displacement of at least one specified point of the tire in at least one of three spatial directions as a function of a spatial position of the at least one specified point during at least one portion of a revolution of the tire, continuously acquiring first signals representing the spatial position of the at least one specified point, deriving from the spatial position signals of the at least one specified point at least one cyclic curve of current operating displacement in at least one spatial direction, continuously comparing the at least one cyclic curve of current operating displacement with the at least one basic reference curve, and emitting a second signal depending on results of the comparison. A related device is also disclosed.

Claims

1. Method for monitoring the instantaneous behaviour of a tire (1) during the running of a motor vehicle, the said tire (1) comprising at least one tread and one casing, three spatial directions—

one longitudinal, one transverse and one vertical—

being associated with the said tire (1), and the said method comprising the steps of

a) acquiring and storing, at least temporarily, at least one basic reference curve which represents the variation of the displacement of at least one specified point of the said tire in at least one of the said three spatial directions, as a function of the spatial position of the said point, in at least one portion of a revolution of the said tire (1),

b) continuously acquiring signals of the position in space of the said at least one point of the said tire (1), in at least one portion of a revolution of the said tire (1),

c) deriving from the said position signals at least one cyclic curve of current operating displacement of the said at least one point in the said at least one of three specified spatial directions, as a function of the spatial position of the said point, in at least the said portion of a revolution of the said tire (1),

d) continuously comparing the said curve of current operating displacement with the said basic reference curve of displacement which is stored, and

e) emitting a signal depending on the said comparison, the said signal indicating the said instantaneous behaviour of the said tire (1).

2. Method according to claim 1, characterized in that the said basic reference curve of displacement mentioned in point a) above is acquired during the running of the motor vehicle on the road, in the course of one revolution of the tire, and is stored temporarily, for a specified period, to make the said comparison, as mentioned in point d) above, with the said curve of operating displacement acquired in a subsequent revolution of the said tire (1).

3. Method according to claim 2, characterized in that the said basic reference curve of displacement which is stored is that of the immediately preceding revolution.

4. Method according to claim 1, characterized in that the said basic reference curve of displacement mentioned in point a) above is acquired in a step which precedes the step of the operation of the said motor vehicle and is stored permanently in order to make the said comparison, as mentioned in point d) above, with the said curve of operating displacement acquired in the said at least one portion of a revolution of the said tire.

5. Method according to claim 1, characterized in that a basic reference curve of velocity of the said at least one point in one spatial direction is stored in the said step a), and a cyclic curve of operating velocity of the said at least one point in one spatial direction is determined in the said step c), the said curves of velocity being obtained, respectively, from the said basic reference curve of displacement and from the said curve of operating displacement by means of a mathematical derivative with respect to time, the said basic reference curve of velocity and the said curve of operating velocity being compared in the said step d).

6. Method according to claims 1 and 5, characterized in that the state of deformation of the said casing in the vicinity of one of its points in an area of contact between the tire and the road is measured by means of the said basic reference curve and the operating curve of displacement or velocity, to evaluate the adhesion present between the tire and the road, and the capacity of the said tire to develop forces tangential to the contact with the said road.

7. Method according to claims 1 and 5, characterized in that signals of the positions of at least two points of the said tire are acquired in the said step b), and the corresponding curves of operating displacement or velocity are also compared with each other in the said step d) to reveal rapid changes in the aforesaid state of deformation or any acquisition errors.

8. Device for monitoring the instantaneous behaviour of a tire (1) during the running of a motor vehicle, the said tire (1) comprising at least one tread and one casing, three spatial directions—

one longitudinal, one transverse and one vertical—

being associated with the said tire (1), and the said device comprising

i. means for acquiring and storing (7a;

7b), at least temporarily, at least one basic reference curve which represents the variation of the displacement of at least one specified point of the said tire in at least one of the said three spatial directions, as a function of the spatial position of the said point, in at least one portion of a revolution of the said tire (1),

ii. at least one sensor means (3;

4) associated with the said at least one specified point of the said tire (1), capable of emitting, over a period of time, signals of the position in space of the said point,

iii. pick-up means (6) capable of continuously acquiring the said signals of the position in space of the said at least one point of the said tire, in at least the said portion of a revolution of the said tire (1), and

iv. processor means (7c) incorporating a program capable of finding from the said position signals at least one cyclic curve of current operating displacement of the said at least one point in the said at least one of three specified spatial directions, as a function of the spatial position of the said point, in at least the said portion of a revolution of the said tire (1),

v. the said processor means (7c) being capable of continuously comparing the said curve of current operating displacement with the said basic reference curve of displacement which is stored,

vi. the said processor means (7c) being additionally capable of emitting a signal depending on the said comparison, the said signal indicating the said instantaneous behaviour of the said tire (1).

9. Device according to claim 8, characterized in that the said storage means (7a) are capable of acquiring and storing temporarily, for a specified time, the said basic reference curve of displacement mentioned in point i) above during the running of the motor vehicle on the road, in the course of one revolution of the tire, and the said processor means carry out the said comparison mentioned in point v) above between the said temporary basic reference curve of displacement and the said curve of operating displacement, acquired in a subsequent revolution of the said tire (1).

10. Device according to claim 9, characterized in that the said stored basic reference curve of displacement is that of the immediately preceding revolution.

11. Device according to claim 8, characterized in that the said storage means (7b) are capable of acquiring and storing permanently the said basic reference curve of displacement mentioned in point i) above in a step which precedes the step of operating the said motor vehicle, and the said processor means carry out the said comparison mentioned in point v) above between the said permanently stored basic reference curve of displacement and the said curve of operating displacement acquired in the said at least one portion of a revolution of the said tire.

12. Device according to claim 8, characterized in that the said processor means (7c) are capable of storing a basic reference curve of velocity of the said at least one point in one spatial direction and are capable of determining a cyclic curve of operating velocity of the said at least one point in one spatial direction, the said curves of velocity being obtained, respectively, from the said basic reference curve of displacement and from the said curve of operating displacement by means of a mathematical derivative with respect to time, the said processor means being capable of comparing the said basic reference curve of velocity with the said curve of operating velocity.

13. Device according to claims 8 and 12, characterized in that the said processor means (7c) measure the state of deformation of the said casing in the vicinity of one of its points in an area of contact between the tire and the road, by means of the said basic reference curve and the operating curve of displacement or velocity, to evaluate the adhesion present between the tire and the road, and the capacity of the said tire to develop forces tangential to the contact with the said road.

14. Device according to claim 8, characterized in that at least two sensor means (3, 4) are associated with at least two points of the said tire (1) and emit at least two signals of the position of the said at least two points, and the said processor means (7c) determine by means of the said signals at least two curves of operating displacement or velocity, and compare them with each other to reveal rapid changes in the aforesaid state of deformation or any errors in acquisition.