METHOD OF MODELLING A TIRE IN RUNNING CONDITIONS AT A DEFINED SPEED
A method is provided for modelling a tire in running conditions at a defined speed. During running, the tire is subjected to a downward vehicle load (F z ) representing a vehicle and to a transverse thrust stress (F y ), and the tire is inclined with respect to a vertical direction by a camber angle (γ). The method includes modelling an overturning moment (Mx) exerted on the tire, in which the overturning moment (Mx) is a sum of at least: a moment (Mx 1 ) produced by an offset of the vehicle load (F z ) by the camber angle (γ); a moment (Mx 2 ) produced by the transverse thrust stress (F y ); a moment (Mx 3 ) produced by a ground reaction (F R ) under the vehicle load (F z ), with the ground reaction (F R ) being decentred from a reference point (C) of the tire by the transverse thrust stress (F y ).
1 - 7 . (canceled)
8 : A method of modelling a tire in running conditions at a defined speed, the tire being subjected to a downward vehicle load (F z ) representing a vehicle and to a transverse thrust stress (F y ), and the tire being inclined with respect to a vertical direction by a camber angle (γ), the method comprising the steps of:
calculating a moment (Mx 3 ) produced by a ground reaction (F R ) of the tire under the vehicle load (F z ); and
modelling an overturning moment (Mx) exerted on the tire as a sum of at least:
a moment (Mx 1 ) produced by an offset of the vehicle load (F z ) by the camber angle (γ),
a moment (Mx 2 ) produced by the transverse thrust stress (F y ), and
the moment (Mx 3 ) produced by the ground reaction (F R ) of the tire under the vehicle load (F z ),
wherein the ground reaction (F R ) of the tire is decentered from a reference point (C) of the tire by the transverse thrust stress (F y ), and
wherein, in the calculating step, the moment (Mx 3 ) is calculated by a formula having a form of:
Mx
31
+
Mx
32
×
(
F
z
-
Mx
33
)
×
γ
+
F
z
×
arctan
(
Mx
34
×
δ
×
F
z
)
×
Mx
35
×
(
1
+
Mx
36
×
V
)
×
(
1
+
Mx
37
×
(
Mx
38
-
P
)
Mx
38
)
,
where Mx 31 , Mx 32 , Mx 33 , Mx 34 , Mx 35 , Mx 36 , Mx 37 and Mx 38 are predefined coefficients, F z is the vehicle load, γ is the camber angle, δ is a drift angle, V is a speed, and P is an inflation pressure.
9 : The method according to claim 8 ,
wherein the drift angle (δ) and the inflation pressure (P) are quantities corresponding to the tire, and
wherein the moment (Mx 3 ) is a function of the vehicle load (F z ), the speed (V), the camber angle (γ), the drift angle (δ), and the inflation pressure (P).
10 : The method according to claim 8 , wherein the coefficients Mx 31 , Mx 31 , Mx 32 , Mx 33 , Mx 34 , Mx 35 , Mx 36 , Mx 37 and Mx 38 are predefined during a preliminary step that includes:
performing bench measurements of the tire, and then
iteratively adjusting the coefficients until a model reproduces the bench measurements to within a predefined error margin.
11 : The method according to claim 8 , wherein the method is used to define a behaviour of a vehicle equipped with the tire.
12 : The method according to claim 11 , wherein the behaviour of the vehicle when rolling over is defined.
13 : A computer-readable storage medium storing a program that, when read by a computer and executed by a computer processor, performs a method of modelling a tire in running conditions at a defined speed, the tire being subjected to a downward vehicle load (F z ) representing a vehicle and to a transverse thrust stress (F y ), and the tire being inclined with respect to a vertical direction by a camber angle (γ), the method comprising steps of:
calculating a moment (Mx 3 ) produced by a ground reaction (F R ) of the tire under the vehicle load (F z ); and
modelling an overturning moment (Mx) exerted on the tire as a sum of at least:
a moment (Mx 1 ) produced by an offset of the vehicle load (F z ) by the camber angle (γ),
a moment (Mx 2 ) produced by the transverse thrust stress (F y ), and
the moment (Mx 3 ) produced by the ground reaction (F R ) of the tire under the vehicle load (F z ),
wherein the ground reaction (F R ) of the tire is decentered from a reference point (C) of the tire by the transverse thrust stress (F y ), and
wherein, in the calculating step, the moment (Mx 3 ) is calculated by a formula having a form of:
Mx
31
+
Mx
32
×
(
F
z
-
Mx
33
)
×
γ
+
F
z
×
arctan
(
Mx
34
×
δ
×
F
z
)
×
Mx
35
×
(
1
+
Mx
36
×
V
)
×
(
1
+
Mx
37
×
(
Mx
38
-
P
)
Mx
38
)
,
where Mx 31 , Mx 32 , Mx 33 , Mx 34 , Mx 35 , Mx 36 , Mx 37 and Mx 38 are predefined coefficients, F z is the vehicle load, γ is the camber angle, δ is a drift angle, V is a speed, and P is an inflation pressure.
14 : A real-time stabilizing system for a vehicle, the system comprising:
a tire; and
a processor programmed to model the tire in running conditions at a defined speed, with the tire being subjected to a downward vehicle load (F z ) and to a transverse thrust stress (F y ), and with the tire being inclined with respect to a vertical direction by a camber angle (γ),
wherein the processor calculates a moment (Mx 3 ) produced by a ground reaction (F R ) of the tire under the vehicle load (F z ), and models an overturning moment (Mx) exerted on the tire as a sum of at least:
a moment (Mx 1 ) produced by an offset of the vehicle load (F z ) by the camber angle (γ),
a moment (Mx 2 ) produced by the transverse thrust stress (F y ), and
the moment (Mx 3 ) produced by the ground reaction (F R ) of the tire under the vehicle load (F z ),
wherein the ground reaction (F R ) of the tire is decentered from a reference point (C) of the tire by the transverse thrust stress (F y ), and
wherein the moment (Mx 3 ) is calculated by a formula in which:
Mx
31
+
Mx
32
×
(
F
z
-
Mx
33
)
×
γ
+
F
z
×
arctan
(
Mx
34
×
δ
×
F
z
)
×
Mx
35
×
(
1
+
Mx
36
×
V
)
×
(
1
+
Mx
37
×
(
Mx
38
-
P
)
Mx
38
)
,
where Mx 31 , Mx 32 , Mx 33 , Mx 34 , Mx 35 , Mx 36 , Mx 37 and Mx 38 are predefined coefficients; F z is the vehicle load, γ is the camber angle, δ is a drift angle, V is a speed, and P is an inflation pressure.