Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M17/00—Testing of vehicles
  • G01M17/007—Wheeled or endless-tracked vehicles
  • G01M17/04—Suspension or damping
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M17/00—Testing of vehicles
  • G01M17/007—Wheeled or endless-tracked vehicles
  • G01M17/06—Steering behaviour; Rolling behaviour

Definitions

• the present invention relates to the field of improving the road behavior of vehicles.
• the manufacturer performs several tests to improve the behavior of the vehicle. These tests include tests, so-called objectives, to quantitatively qualify the behavior of the vehicle and so-called subjective tests, to qualitatively qualify the behavior of the vehicle.
• the subjective tests are carried out by testers who drive the vehicle and describe its behavior according to their impression.
• Objective tests include braking tests, adhesion, safety.
• Subjective tests include topics relating to behavior around the straight line, general behavior and active safety.
• the behavior around the straight line includes maneuvers performed for low lateral accelerations of the vehicle for example maneuvers said direction, linearity, driving pleasure, centering, etc. ..
• the heading relating to the behavior around the straight line is intended in particular to qualify the response of the vehicle according to a generally low demand steering angle amplitude exerted by the tester, that is to say say for example how the steering wheel torque or the yaw of the vehicle vary qualitatively and quantitatively in response to a steering wheel angle variation during a taxi at a steady speed, for example of the order of 100 km / h.
• a vehicle having a linear response has a behavior generally deemed satisfactory by the tester while a vehicle whose response is non-existent for a low angle of rotation of the steering wheel exhibits a behavior generally considered unacceptable for the tester.
• the vehicle is modified and then retried by the tester so that the latter check if the vehicle shows satisfactory behavior following the modifications made.
• the requests for changes are based on the experience of the latter. They relate in a non-exhaustive way the tires, the wheels, the steering system, the geometry and the elements of the suspension device. The steps listed above are repeated until the vehicle exhibits behavior around the straight line satisfactory to the tester.
• the vehicle design is relatively long and therefore expensive.
• wheel is taken in a particular sense, the wheel is then made of a disk and a rim, or in a general sense which corresponds to the mounted assembly consisting of a wheel (disc and rim) and a tire.
• the object of the invention is to provide a method of characterizing a given vehicle comprising a body, at least one wheel with a disk, a rim and a tire and at least one connecting suspension device. the wheel at the checkout.
• (D) determining in the plane Fy, Dy Z zones of acceptable behavior of the vehicle.
• the configuration of the suspension device and the wheel disk is modified by varying a parameter chosen in the group of the angle of clamp / opening, the camber angle, the offset of the wheel.
• the subjective behavior test is a behavior test with low lateral accelerations.
• the lateral force value pair Fy and lateral offset Dy are determined. in running straight relative to a reference configuration of the suspension device and the wheel disk.
• the lateral offset of the wheel is varied by introducing shim chops between the wheel disk and the suspension device and the variation in lateral offset is estimated by the thickness of the shims introduced.
• a vehicle model is used to obtain the relationships between the accelerations imposed on the center of gravity of the vehicle and the forces, moments and attitudes of the wheels of the vehicle to obtain the forces, moments and attitudes at the center-wheel of the wheel. rolling straight line;
• step (C) the rolling condition of the wheel is varied and step (B) is repeated;
• the invention is a method of choosing at least one wheel equipped with a tire of a vehicle in which:
• the vehicle is characterized by the previously described method to obtain the zones Z of acceptable behavior of the vehicle;
• the methods of the invention can be implemented wheel by wheel or axle by axle with respect to the characterization of the vehicle.
• the advantage of working axle by axle is to preserve for the tests of the subjective behavior the symmetry right / left.
• the main advantage of these methods is to independently characterize the vehicle, the wheels and the tires and from these characterizations to directly determine the choice of tires and wheels giving the vehicle a good behavior in rolling at low lateral accelerations and if necessary to guide the adjustment of the vehicle to obtain a good adaptation of the available tires. From a given given vehicle, the skilled person tire manufacturer, can also define the tire architecture characteristics necessary to directly obtain a satisfactory behavior of the vehicle equipped with these tires.
• FIG. 1 shows an axial sectional view of a vehicle wheel
• FIG. 2 shows schematically the forces and moments applied to the wheel mounted on a suspension device
• FIG. 4 shows a characterization in the plane Fy, Dy of a wheel.
• FIG 1 there is shown a vehicle wheel, in the particular sense defined above, comprising a disk D and a rim J.
• geometric elements usually identified on a wheel namely the median plane M and the axis A of the wheel and the center CA of the wheel, usually called center-wheel.
• the center CA is a point defined by the intersection of the axis A of the wheel and a face of the disk D intended to bear on a hub carrying the wheel.
• FIG. 1 There is also shown in Figure 1 a geometric reference whose origin is MA, intersection between the axis A and the median plane M, said wheel marker.
• This reference comprises axes X, Y and Z, orthogonal to each other, respectively corresponding to the usual directions longitudinal (X axis), transverse (Y axis) and vertical (Z axis) of a vehicle wheel.
• the transverse axis Y can also be denoted lateral axis or
• the positive direction of the Y axis is directed from the outside to the inside of the vehicle and the negative direction of the Y axis is directed from the inside to the outside of the vehicle. vehicle.
• a substantially longitudinal axis torque is considered positive when it tends to decrease the camber angle of the wheel and as negative when it tends to increase the camber angle of the wheel.
• the camber angle of a wheel is the angle that makes, in a plane perpendicular to the ground and containing the axis A of the wheel, the median plane M of the wheel with the median plane of the vehicle. We speak of against camber (or negative camber) when the median planes M wheels of the same axle intersect above the ground.
• Figure 2 shows very schematically the forces and moments applying to a wheel equipped with a tire P mounted on a suspension device 80 of a front axle of a vehicle.
• the suspension device 80 is shown schematically by a damper 82 and a suspension arm 84 both connected to the hub 86.
• the wheel 14 exerts a moment around the axis X on the suspension device: MX.
• This moment has two components, the first MXy is related to the resultant or barycentre of the forces in the contact area oriented along the Y axis or lateral force Fy, and the second MXz is related to the resultant of the efforts in the area contact points oriented along the Z axis or vertical force Fz.
• the first component MXy is equal to the product of the lateral force Fy by the rolling radius or crushed radius Re.
• the second MXz is equal to the product of the vertical force Fz by the offset of the wheel Dy.
• the offset of the wheel Dy corresponds to the offset between CA, the wheel center and the point of application of the vertical forces Fz.
• This offset has two components, a geometric component related to the value DyO previously illustrated, distance between CA and the median plane of the wheel M, and a dynamic component corresponding to the distance between the median plane of the wheel and the centroid of the vertical forces Fz.
• This dynamic component is called Dyp.
• the offset of the wheel can thus be obtained from measurements at the wheel center of the lateral force Fy, the vertical force Fz and the torque along the longitudinal axis MX with the measurement of the rolling radius or crushed radius Re .
• the moment along the longitudinal axis MX exerted by the wheel on the suspension device can be modified by two different ways, by variations of the lateral force Fy and by modifications of the offset of the wheel Dy.
• the lateral force Fy can be measured either at the wheel center or in the contact area of the tire on the ground.
• the method of characterizing the behavior of a vehicle according to an object of the invention is to perform subjective behavior tests at low side accelerations of the vehicle equipped with known tires by varying the configuration of at least one device. suspension and the associated wheel of the vehicle and preferably the two suspension devices and their associated wheels of the same axle.
• This scanning can be performed by varying the lateral force Fy in running straight line at a given stabilized speed, of the order of 100 km / h or more depending on the vehicles considered. This is achieved in particular by modifying the angles of clamp or opening of the two suspension devices considered. It is recalled that the gripper angle corresponds in running straight line to the angle between the median plane of the vehicle and the median plane of the wheel. This angle is called a clamp angle when the two median planes of the two wheels of an axle cross in front of the vehicle and is called opening in the opposite case.
• the sweeping can also be performed by varying the geometric offset of the wheel DyO, for example by inserting shim chops between the wheel center and the hub of the axle (negative variation) or by abrading the face of the wheel. disk in contact with the hub (positive variation of the geometric offset).
• Figure 3 shows the results of a characterization of a passenger vehicle. The sweeping of the conditions of the two suspension devices and their associated wheels of the same axle, the front axle of the vehicle, was realized taking as reference a given setting of parallelism and lateral offset of the two wheels. From these reference conditions, the Fy force was varied by progressively varying the parallelism of the vehicle, ie the clamp angles and opening up to determine the optimum behavior of the vehicle for the given wheel offset setting.
• Figure 4 shows the result of the characterization of a wheel having a tire, a rim and a given disk and a given geometric offset.
• the results show a direct, almost linear relationship between the wheel offset Dy and the lateral force Fy.
• a model of the vehicle can in particular be obtained by static characterizations on a K & C type bench. Such a model makes it possible to connect the accelerations to the center of gravity of the vehicle and the forces, moments and attitudes of the wheels of the vehicle for to obtain the forces, moments and attitudes at the center-wheel of the wheel while rolling straight line, and in particular the lateral forces Fy and radial Fz as well as the moment along the longitudinal axis MX and the rolling radius Re.
• a person skilled in the tire art can, in particular, adjust the tire construction parameters, for example their taper and their drift rigidity to play on the lateral forces as well as the relationship between the dynamic lateral offset and the the lateral force of the tire to obtain a priori excellent behavior of the vehicle equipped with these tires.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Vehicle Body Suspensions (AREA)
• Tires In General (AREA)
• Body Structure For Vehicles (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=47989295

Family Applications (1)

Country Status (7)

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• 2013
  • 2013-01-31 FR FR1350804A patent/FR3001541B1/fr not_active Expired - Fee Related
• 2014
  • 2014-01-29 EP EP14701576.2A patent/EP2951551A1/de not_active Withdrawn
  • 2014-01-29 CN CN201480006987.6A patent/CN104956196B/zh not_active Expired - Fee Related
  • 2014-01-29 US US14/763,969 patent/US9435715B2/en not_active Expired - Fee Related
  • 2014-01-29 JP JP2015555689A patent/JP6373875B2/ja not_active Expired - Fee Related
  • 2014-01-29 WO PCT/EP2014/051696 patent/WO2014118214A1/fr active Application Filing
  • 2014-01-29 BR BR112015018159A patent/BR112015018159A8/pt not_active Application Discontinuation

Non-Patent Citations (2)

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