Method for characterizing the behaviour of a vehicle and use in the selection of the tyres of the vehicle

Patent metadata

Field	Value
Publication number	US-9435715-B2
Application number	US-201414763969-A
Country	US
Kind code	B2
Filing date	Jan 29, 2014
Priority date	Jan 31, 2013
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

To characterize a behavior of a vehicle, a subjective behavior test is conducted on a given configuration of a suspension device and a wheel disc of the vehicle to determine whether the vehicle's behavior is acceptable. Modifications are made to the given configuration so as to sweep through pairs of values corresponding to a lateral force Fy and a lateral offset Dy of the wheel in straight-line running. For each modified configuration of the suspension device and/or the wheel disc, the subjective behavior test is conducted again. For each configuration of the suspension device and the wheel disc tested, a determination is made of a pair of values of the lateral force Fy and the lateral offset Dy of the wheel in straight-line running. Areas Z of acceptable behavior of the vehicle in a plane Fy, Dy are determined.

First claim

The invention claimed is:

1. A method for characterizing a behavior of a vehicle that includes a body, a wheel having a wheel disc, a rim, and a tire, and a suspension device connecting the wheel to the body, the method comprising steps of:
for a physical configuration of the suspension device and the wheel disc, conducting a behavior test on the vehicle to determine whether the behavior of the vehicle is acceptable in straight-line running at a stabilized speed, the physical configuration corresponding to a reference pair of conditions for a lateral force (Fy) and a lateral offset (Dy) of the wheel in straight-line running;
modifying the physical configuration of the suspension device and the wheel disc a plurality of times so as to sweep through pairs of conditions presenting variations (ΔFy, ΔDy) from the reference pair of conditions for the lateral force (Fy) and the lateral offset (Dy) of the wheel in straight-line running, and, for each of the plurality of modified physical configurations of the suspension device and the wheel disc, conducting the behavior test again to determine whether the behavior of the vehicle is acceptable in straight-line running at the stabilized speed;
for each physical configuration and each of the modified physical configurations of the suspension device and the wheel disc tested, determining Fy, Dy values of the lateral force (Fy) and the lateral offset (Dy) of the wheel in straight-line running at the stabilized speed; and
representing, on a chart, Z-area pairs of the Fy, Dy values corresponding to acceptable configurations of the modified physical configurations and the physical configuration for which the acceptable behavior of the vehicle has been determined, the acceptable behavior being a linear response behavior in straight-line running at the stabilized speed,
wherein the chart showing the Z-area pairs is utilizable to optimize at least one of: a tire structure, a wheel structure, a vehicle structure, and a selection of a wheel and a tire for the vehicle.

2. The method according to claim 1 , wherein the step of modifying the physical configuration is performed by varying at least one of: a toe-in/toe-out parameter, a camber parameter, and an offset parameter of the wheel.

3. The method according to claim 1 , wherein the behavior test is conducted at a low lateral acceleration.

4. The method according to claim 1 , wherein, in the step of determining the Fy, Dy values, a value of the lateral force (Fy) and a value of the lateral offset (Dy) of the wheel are determined with respect to the physical configuration, which corresponds to a reference configuration of the suspension device and the wheel disc.

5. The method according to claim 4 ,
wherein, in the step of modifying the physical configuration, the lateral offset (Dy) of the wheel is varied by inserting at least one camber shim of a known thickness between the wheel disc and the suspension device, and, in the step of determining the Fy, Dy values, a value of the lateral offset (Dy) of the wheel is estimated from a total thickness of the at least one camber shim inserted, and
wherein, in the step of modifying step the physical configuration, the lateral force (Fy) of the wheel is varied by changing a toe-in or toe-out parameter, and, in the step of determining the Fy, Dy values, a value of the lateral force (Fy) is estimated from a product of a drift rigidity of the tire and the toe-in or toe-out parameter.

6. The method according to claim 1 , further comprising steps of:
using a model of the vehicle to determine relationships between an acceleration imparted to a center of gravity of the vehicle and forces, moments, and attitudes of vehicle wheels, in order to determine forces, moments, and attitudes at a wheel center of the wheel in straight-line running;
using a characterization relating the lateral force (Fy) to the lateral offset (Dy) of the wheel; and
for each physical configuration of the suspension device tested, determining a pair of values of the lateral force (Fy) and the lateral offset (Dy) of the wheel in straight-line running at the stabilized speed based on the model and the characterization.

7. The method according to claim 6 , further comprising a step of characterizing the wheel by:
mounting the wheel on a test machine, the test machine being structured to cause the wheel to roll on a moving rolling surface in given conditions, and to enable a rolling radius and a set of forces and moments at the wheel center to be measured;
rotating the wheel in a given rolling configuration, and measuring the rolling radius Re, a radial force (Fz), the lateral force (Fy), and a moment (MX) along a longitudinal axis;
varying a rolling condition of the wheel, and repeating the steps of rotating and measuring; and
determining a characteristic Fy=f(Dy), such that:
Dy =( MX−Fy*Re )/ Fz.

8. The method according to claim 1 , wherein the method is executed for each assembly of a suspension device and a wheel of the vehicle, in succession.

9. The method according to claim 1 ,
wherein the vehicle includes at least two axles, each axle of the at least two axles being fitted with two suspension devices and two wheels, and
wherein the method is executed axle by axle.

10. The method according to claim 6 , further comprising a step of selecting a wheel and tire combination, the selecting including:
characterizing the vehicle according to the Z-area pairs representing conditions of acceptable behavior of the vehicle,
characterizing the wheel by determining a characteristic Fy=f(Dy) of the wheel, and
selecting the wheel and tire combination by adjusting the suspension device of the vehicle in such a way that the vehicle when fitted with the wheel and tire combination exhibits a pair of values of the lateral force (Fy) and the lateral offset (Dy) in straight-line running in an area corresponding to one of the Z-area pairs representing conditions of acceptable behavior of the vehicle.

11. A method for characterizing a behavior of a vehicle that includes a body, a wheel having a wheel disc, a rim, and a tire, and a suspension device connecting the wheel to the body, the method comprising steps of:
using a model of the vehicle to determine relationships between an acceleration imparted to a center of gravity of the vehicle and forces, moments, and attitudes of vehicle wheels, in order to determine forces, moments, and attitudes at a wheel center of the wheel in straight-line running;
using a characterization relating a lateral force (Fy) to a lateral offset (Dy) of the wheel;
for each physical configuration of a plurality of physical configurations of the suspension device, determining a pair of values of the lateral force (Fy) and the lateral offset (Dy) of the wheel in straight-line running at a stabilized speed; and
for each physical configuration of the plurality of physical configurations, performing a behavior test to determine whether the vehicle exhibits a linear response behavior in straight-line running at the stabilized speed,
wherein pairs of values (Fy, Dy) corresponding to physical configurations determined to cause the vehicle to exhibit the linear response behavior are utilizable to optimize at least one of: a tire structure, a wheel structure, a vehicle structure, and a selection of a wheel and a tire of the vehicle.

12. The method according to claim 11 , further comprising a step of characterizing the wheel by:
mounting the wheel on a test machine, the test machine being structured to cause the wheel to roll on a moving rolling surface in given conditions, and to enable a rolling radius and a set of forces and moments at the wheel center to be measure

Assignees

• Michelin & Cie
• Michelin Rech Tech

Inventors

• Egerszegi Christophe

Classifications

• G01M17/06

  Steering behaviour; Rolling behaviour · CPC title

• G01M17/04 Primary

  Suspension or damping · CPC title