# US 11,999,204 B2 · Method for obtaining the deformation of a tire under load during running

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- Number: US 11,999,204 B2
- Document ID: US11999204B2
- Status: Granted
- Kind: B2
- Application number: 17/416,872
- Filed: 2019-12-16
- Published: 2022-03-17
- Granted: 2024-06-04
- Earliest claimed: 2018-12-21
- Assignees: Compagnie Generale Des Etablissements Michelin
- Applicants: Compagnie Generale Des Etablissements Michelin
- Inventors: Denis Alff
- Web page: https://patentgrep.com/patent/US11999204B2

## CPC

- B60C 11/246: {Tread wear monitoring systems}
- B60C 23/061: {by monitoring wheel speed (measuring distance traversed on the ground by vehicles G01C22/00)}
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES

## Abstract

A method for obtaining the deformation of a tire casing subjected to a load, rotating at a rotational speed W, comprises the following steps: acquiring a signal comprising the amplitude of the acceleration in the direction normal to the crown when running at the rotational speed W; delimiting the signal over a number of wheel revolutions, so as to construct a wheel revolution signal; determining a reference acceleration; defining a first energy density S which is a function of the wheel revolution signal, and of the reference acceleration, and which is denoted S+ when the wheel revolution signal is above a threshold value A, or is denoted S− when the wheel revolution signal is below or equal to said threshold value A; and identifying the deformation generated by the load as a function of the reference acceleration and of the first energy density S.

## Claims

### Claim 1

A method for obtaining the deformation of a tire casing subjected to a load, in an inflated and laden state rotating at a rotational speed W, the tire casing having a crown, two sidewalls and two beads of revolution about a natural axis of rotation and a median plane, an intersection between the median plane and the natural axis of rotation defining a wheel center, the method comprising the following steps:
fixing at least one sensor on the tire casing in line with the crown at a radial position R with respect to the natural axis of rotation, the sensor being configured to generate at least one output signal proportional to acceleration experienced by the sensor in the tire casing;
acquiring a first signal comprising at least the amplitude of the acceleration in a direction normal to the crown when running at the rotational speed W;
delimiting the first signal over a number NTdR of wheel revolutions, NTdR being greater than or equal to 1, so as to construct a wheel revolution signal;
determining a reference acceleration γreference that is a function of the rotational speed W and of the position of the at least one sensor;
defining a first energy density S which is a function of the wheel revolution signal, and of the reference acceleration γreference, and which is denoted S+ when the wheel revolution signal is above a threshold value A, or is denoted S− when the wheel revolution signal is below or equal to the threshold value A; and
identifying the deformation of the tire casing, which deformation is generated by the load as a function of the reference acceleration γreference and of the first energy density S which are associated with a position of the at least one sensor.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the identification of the deformation of the tire casing subjected to a load is determined using the following formula:
Def
%
=
(
S
)
(
N
TdR
*
γ
Reference
)
.
[
Math
⁢
⁢
1
]

### Claim 3 (depends on 1)

The method according to claim 1, wherein the identification of the deformation of the tire casing subjected to a load is determined using the following formula:
Def
%
=
(
S
+
+
S
-
)
(
2
*
N
TdR
*
γ
Reference
)
.
[
Math
⁢
⁢
2
]

### Claim 4 (depends on 1)

The method according to claim 1, wherein the delimitation of the first signal over a number NTdR of wheel revolutions is achieved by the first signal crossing below or above a threshold value less than or equal to half the value of the reference acceleration γreference.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the threshold value A for defining the first energy density is a function of the reference acceleration γreference.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the threshold value A for defining the first energy density is a function of a factor C, the factor C being greater than or equal to 0.5 and less than or equal to 0.9, using the following formula:
A=C*γReference [Math 3].

### Claim 7 (depends on 1)

The method according to claim 1, wherein the determination of the reference acceleration γreference is defined using the following formula:
γreference=R*W2 [Math 4].

### Claim 8 (depends on 1)

The method according to claim 1, wherein the determination of the reference acceleration γreference is defined as a mean value for the wheel revolution signal SigTdR.

### Claim 9 (depends on 1)

The method according to claim 1, further comprising the step of, having phased the wheel revolution signal SigTdR with respect to an angular position of the tire casing, making a correction Corr to the wheel revolution signal SigTdR to take account of the effect of the Earth's gravity.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the energy densities that are negative S− and positive S+ are defined according to the following formulae:
S+=|∫SigTdR>AU(SigTdR−γReference)*du| [Math 5a]; and
S−=|∫SigTdR≤AU(SigTdR−γReference)*du| [Math 5b];
where u is an abscissa value of the wheel revolution signal SigTdR.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the acquisition of the first signal is performed for a rotational speed W greater than or equal to a threshold rotational speed Wseuil defined by the following formula:
W
seuil
=
12
Dev
,
[
Math
⁢
⁢
6
]
where Dev is the development of the tire casing.

### Claim 12 (depends on 1)

The method according to claim 1, wherein the acquisition of the first signal is performed at a constant sampling frequency and a spatial discretization of the sampling of the first signal is less than 6 degrees.

### Claim 13 (depends on 12)

The method according to claim 12, wherein the energy densities that are negative S− and positive S+ are defined according to the following formulae:
S
+
=

Σ
Sig
TdR
>
A
⁡
(
Sig
TdR
-
γ
Reference
)

*
N
TdR
N
U
;
and
[
Math
⁢
⁢
7
⁢
a
]
S
-
=

Σ
Sig
TdR
≤
A
⁢
(
Sig
TdR
-
γ
Reference
)

*
N
TdR
N
U
,
[
Math
⁢
⁢
7
⁢
b
]
where NU is the total number of points discretized in the wheel revolution signal SigTdR.

### Claim 14 (depends on 12)

The method according to claim 12, wherein the determination of the reference acceleration γreference is defined using the following formula:
γ
reference
=
(
Σ
Sig
TdR
⁢
Sig
TdR
)
N
U
,
[
Math
⁢
⁢
8
]
where NU is the total number of points discretized in the wheel revolution signal SigTdR.

### Claim 15 (depends on 12)

The method according to claim 12, wherein the energy densities that are negative S− and positive S+ are defined according to the following formulae:
S
+
=

Σ
Sig
TdR
>
A
⁡
(
Sig
TdR
-
γ
Reference
)

*
N
TdR
N
U
;
and
[
Math
⁢
⁢
7
⁢
a
]
S
-
=

Σ
Sig
TdR
≤
A
⁢
(
Sig
TdR
-
γ
Reference
)

*
N
TdR
N
U
,
[
Math
⁢
⁢
7
⁢
b
]
wherein the determination of the reference acceleration γreference is defined using the following formula:
γ
reference
=
(
Σ
Sig
TdR
⁢
Sig
TdR
)
N
U
,
[
Math
⁢
⁢
8
]
where NU is the total number of points discretized in the wheel revolution signal SigTdR; and
wherein the identification of the deformation of the tire casing subjected to a load is determined using the following formulae:
Def
%
=

Σ
Sig
TdR
>
A
⁡
(
Sig
TdR
-
γ
Reference
)

(
Σ
Sig
TdR
⁢
Sig
TdR
)
;
or
[
Math
⁢
⁢
9
⁢
a
]
Def
%
=

Σ
Sig
TdR
≤
A
⁡
(
Sig
TdR
-
γ
Reference
)

(
Σ
Sig
TdR
⁢
Sig
TdR
)
;
or
[
Math
⁢
⁢
9
⁢
b
]
Def
%
=

Σ
Sig
TdR
>
A
⁡
(
Sig
TdR
-
γ
Reference
)

+

Σ
Sig
TdR
≤
A
⁡
(
Sig
TdR
-
γ
Reference
)

(
2
*
(
Σ
Sig
TdR
⁢
Sig
TdR
)
)
.
[
Math
⁢
⁢
9
⁢
c
]