JP2008049725A - Method for designing tire in consideration of tire friction ellipse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine a dynamic characteristic of a tire that can be realized at the time of designing the tire as its requisite characteristic. <P>SOLUTION: Parameter values having characteristic curves of a tire longitudinal force, lateral force and self-aligning torque approximated by "Magic Formula" are applied to a vehicle model, their simulations are carried out to perform a performance evaluation. In this case, when the vehicle model does not fulfill a predetermined performance, the parameter values are corrected to perform the vehicle performance evaluation again and at the same time the tire performance curves defined by the corrected parameter values are calculated and the values of tire dynamics element parameters are calculated on the basis of a tire dynamics model in reference to the tire performance curves. The tire dynamics model is that in which a center position of a ground contact surface moves according to the generated longitudinal force when a slip ratio in a brake driving direction is given. In the case where the vehicle model fulfills the predetermined performance, the values of tire dynamics element parameters corresponding to the parameters are defined as tire requisite characteristics. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tire design method that takes into account a tire friction ellipse that determines a required characteristic of a tire by performing a running simulation of the vehicle in order to realize desired vehicle performance.

Currently, in the initial stage of vehicle development, determination of vehicle specifications that achieve desired vehicle performance is performed by performing a simulation using a computer and determining whether to achieve desired vehicle performance. In other words, a vehicle model is generated based on the set vehicle specification data, a tire driving force is applied to the vehicle model, a vehicle running simulation is performed, and the vehicle performance evaluation for the vehicle specification is performed from the simulation result. Is called.
In particular, when performing a running simulation of a vehicle, the tire is the only component that transmits the force received from the road surface to the vehicle, and therefore it is necessary to accurately determine the generated force of the tire. The generated force described here is a longitudinal force and a lateral force during cornering. As the generated force of this tire, the characteristic curve indicating the slip angle dependency of the lateral force and self-aligning torque generated during cornering of the tire, the characteristic curve of the longitudinal force generated during braking and driving, and also during braking and cornering It has been proposed to approximate the characteristic curves of the longitudinal force, lateral force, and self-aligning torque generated in the interior by a “Magic Formula” represented by the following basic formula (20).
Y (x) = Dsin [Ctan ⁻¹ {Bx−E (Bx−tan ⁻¹ (Bx))}] (20)
“Magic Formula” is a non-analytic model that uses a nonlinear approximation expression that represents tire characteristics by determining the values of parameters B to E in Expression (20). In this model, for example, the lateral force F _{y in the} case of representing a composite characteristic such as “the change in the slip angle dependency of the lateral force due to the slip rate S” is applied with the slip rate represented by the above formula (20). For the lateral force F _y0 under the above condition, correction is made as shown in the following formula (21). The above correction is applied to the longitudinal force and the self-aligning torque as well as the lateral force.
F _y = G _yk · F _y0 + S _vyk (21)
(G _yk : coefficient related to slip ratio S, S _vyk : coefficient related to slip ratio S)
It is common practice to perform a vehicle running simulation using values of parameters “B” to “ _E ”, “G _yk ”, “S _vyk ”, and the like (hereinafter referred to as “Magic Formula” parameters) of the “Magic Formula”.

  In particular, tire manufacturers who deliver tires to automobile manufacturers perform vehicle running simulations using the values of the parameters of the “Magic Formula”, so that the desired performance can achieve the target value. The parameter value is determined, and the tire structural design and material design are performed to realize the parameter value.

The following Patent Document 1 discloses a tire design method capable of performing an optimum design by evaluating tire performance in combination with a vehicle on which a tire is mounted.
FIG. 17 is a diagram illustrating a flow of the tire design method disclosed in Patent Document 1.

Specifically, a tire running simulation is performed by modeling with a finite element of the tire based on the input of the design value of the tire. By this running simulation, tire characteristic data is calculated, and parameters of “Magic Formula” are obtained from the tire characteristic data.
On the other hand, a vehicle model, which is a mechanism analysis model, is created based on the setting of vehicle specification data. Next, a travel simulation condition is set, and the travel simulation of the vehicle is performed by being given to the vehicle model together with the previously obtained “Magic Formula” parameter. Performance evaluation data is calculated from the result of the running simulation.
In general, for example, in the case of durability performance, the maximum value of stress applied to a specific member and the deformation amount of the specific member are used as performance evaluation data. In the case of emergency avoidance performance, the stability based on the time trace of the relationship between the traveling speed of the vehicle and the maximum lateral acceleration or the slip angle of the vehicle and the rate of change thereof is evaluated.
When the performance evaluation data does not achieve the target value, it is determined that the target is not achieved, and the design value of the tire is corrected. In response to this correction, a tire model composed of finite elements is regenerated.
In this way, the design value of the tire is repeatedly corrected until the performance evaluation data in the vehicle travel simulation result achieves the target value. When the performance evaluation data achieves the target value, the modified tire design value is determined as the tire design specification.

  However, in the above design method, if the specified target performance cannot be achieved in the performance evaluation, the design value of the tire (the shape of the tire, the dimensions of each part of the tire, etc.) is corrected. It is difficult to understand how the “Formula” parameter is modified by the modified tire design value, and it is not fully understood whether the target performance is approached by modifying the tire design value. For this reason, in order to correct the design value of the tire and efficiently determine the design specification of the tire, it is necessary to be performed by a skilled designer, and no one can easily determine the design specification. That is, since the tire is modeled finely with a finite element, there are a large number of parts to be corrected, and it is often unclear where to correct, and it is necessary to rely on a skilled designer. In addition, every time the design value of the tire is corrected, there is a complexity of regenerating a tire model that is a finite element model. Further, it is necessary to repeat many time-consuming tire running simulations and vehicle running simulations, and it is difficult to efficiently find tire design values that achieve satisfactory performance. In particular, it is difficult to efficiently find a design value of a tire in a vehicle running simulation in which a slip angle and a slip ratio in the braking / driving direction are given to the tire.

JP 2002-356106 A

  Accordingly, the present invention provides tire dynamics in which approximate expression parameters in approximate expressions such as “Magic Formula” expressed as tire cornering characteristics and braking / driving characteristics when a slip ratio is given to the tire include various rigidity of the tire. Tire design specifications that are linked to element parameters and that can be used to determine the value of approximate formula parameters such as `` Magic Formula '' and achieve target performance regardless of whether or not they are skilled designers An object of the present invention is to provide a tire design method capable of efficiently determining the tire.

According to the present invention, the characteristic curve information representing the slip ratio dependency of at least one of the tire axial force and the torque acting on the tire rotation shaft when the slip ratio is given to the tire and the vehicle specification information are obtained. A tire design method that takes into account tire friction ellipses to design a tire that achieves a desired performance by performing a vehicle running simulation using the vehicle specification information and creating a vehicle model using vehicle specification information Based on a tire dynamic model configured using a creating step and a plurality of tire dynamic element parameters, a value of the tire dynamic element parameter that defines the characteristic curve is set, and a characteristic curve calculated by the tire dynamic element parameter When the vehicle model is approximated with a nonlinear approximation formula, the value of the approximate formula parameter that defines the nonlinear approximation formula is attached to the vehicle model. A performance evaluation step of performing a travel simulation under a predetermined travel condition and evaluating the performance of the vehicle using a result of the travel simulation; and in the performance evaluation, if the vehicle model does not satisfy the target performance, the approximate expression The parameter value is corrected, the corrected value is assigned to the vehicle model, a running simulation is performed, the vehicle performance is evaluated using the result of the running simulation, and the value of the approximate expression parameter is corrected. A tire characteristic correcting step for deriving a value of the tire dynamic element parameter based on the tire dynamic model using a characteristic curve calculated from a prescribed nonlinear approximate expression, and the vehicle model satisfies a predetermined performance In this case, the derived value of the tire dynamic element parameter is determined as a tire target characteristic. And a tire characteristic determination step, wherein when the slip rate in the braking / driving direction is given, the position of the ground contact surface with respect to the road surface of the tire is changed in the front-rear direction by the longitudinal force generated as the tire axial force. Provided is a tire design method that takes into account a tire friction ellipse, which is a model in which the center position of a contact surface moves in accordance with the generated longitudinal force so as to move.
The slip ratio in the present invention includes both a slip angle and a slip ratio in the braking / driving direction. When the slip angle is α, the slip rate in the lateral direction can be expressed as tan α and integrated with the slip rate in the braking / driving direction. Therefore, the slip rate-dependent characteristic curve in the present invention includes a slip angle-dependent characteristic curve in addition to the slip rate-dependent characteristic curve in the braking / driving direction.
Further, “considering the tire friction ellipse” means that the tire characteristics caused by the slip angle given to the tire and the slip ratio in the braking / driving direction are taken into consideration.

  Further, the tire dynamic model calculates a lateral force when a slip angle is given to the tire, a self-aligning torque, a lateral force torque component generated by a lateral force acting on the tire contact surface, It is preferable that the self-aligning torque be calculated separately for the longitudinal force torque component generated by the longitudinal force acting on the contact surface.

  Further, the tire axial force includes at least a lateral force acting in a direction parallel to the tire rotation axis when a slip ratio is given to the tire, and when calculating the characteristic curve using the tire dynamic model In addition to the lateral force characteristic curve, it is preferable to calculate a slip rate-dependent characteristic curve of the self-aligning torque generated by the lateral force and the longitudinal force acting on the road surface.

  In that case, when deriving the value of the tire dynamic element parameter in the tire characteristic correction step, the sum of square residuals of the characteristic curve of the longitudinal force and the corresponding curve of the longitudinal force calculated by the tire dynamic model, The sum of square residuals of the characteristic curve of the lateral force and the corresponding curve of the lateral force calculated by the tire dynamic model, the self-aligning torque calculated by the characteristic curve of the self-aligning torque and the tire dynamic model Is a value obtained by weighting and adding a square residual sum with a corresponding curve of each of the characteristic curves of the longitudinal force, the lateral force, and the self-aligning torque as the weighting factor. , So that the value of the composite square residual sum using the coefficient obtained from the information on the variation of the value that varies depending on the slip ratio is less than or equal to the predetermined value. It is preferred to derive the values of the tire dynamic element parameters.

  Further, in the tire characteristic correction step, when deriving the value of the tire dynamic element parameter from the characteristic curve based on the tire dynamic model, it is given by the torsional deformation of the tire generated by the self-aligning torque. It is preferable to derive the value of the tire dynamic element parameter using the effective slip angle in which the slip angle is corrected.

  Further, the value of the tire dynamic element parameter derived in the tire characteristic correcting step is a coefficient for defining the adhesion friction coefficient between the tire tread member and the road surface, a coefficient of sliding friction, and a shape defining coefficient that defines the shape of the contact pressure distribution. It is preferable to include.

Further, when the slip angle and the slip ratio in the braking / driving direction are given as the slip ratio, the tire dynamic model calculates the slip area in the contact surface when calculating the longitudinal force, the lateral force, and the self-aligning torque. The slip direction of the tire is determined by the given slip angle and the slip ratio in the braking / driving direction, and it is preferable to calculate the longitudinal force, lateral force, and cell aligning torque using the slip direction.
Furthermore, it is preferable to design a tire by using a value of the tire dynamic element parameter determined in the tire characteristic determining step to determine a combination of a tire member material and a tire structure that realizes the value.

  In the present invention, an approximate expression parameter is given to the vehicle model to perform a travel simulation. If the vehicle model does not satisfy the target performance in the performance evaluation at that time, the approximate expression parameter is corrected and the travel simulation is performed again. At this time, a characteristic curve is calculated from the nonlinear approximation formula defined by the corrected approximation formula parameter, and the value of the tire dynamic element parameter is derived from the characteristic curve based on the tire dynamic model. For this reason, the approximate expression parameters in the nonlinear approximate expression expressed as the cornering characteristics of the tire given the slip angle and the slip ratio in the braking / driving direction are linked to the tire dynamic element parameters including various tire stiffnesses. Even if not, the tire design specifications can be determined efficiently using parameters that can be realized in an actual tire.

  The tire dynamic element parameters are parameters that are easily understood by the tire manufacturer, and since it is relatively known what tire dimensions and shapes should be used to adjust the tire dynamic element parameters, A trader can easily design a tire based on the determined tire design specification.

  Hereinafter, a tire design method considering a tire friction ellipse according to the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

FIG. 1 is a configuration diagram of an apparatus 1 that implements a tire design method considering a tire friction ellipse according to the present invention. The apparatus 1 includes a computer that performs a tire design method by executing various programs.
The device 1 is a vehicle specification data (wheel base, height of center of gravity, total weight of the vehicle, weight distribution of the front and rear wheels of the vehicle, etc.) and the movement of the tire when a slip ratio is given to the tire which is a component of the vehicle. This is a device that determines the required characteristics of a tire that achieves desired vehicle performance from information on characteristics (cornering characteristics and braking / driving characteristics of a tire) (hereinafter, these characteristics are referred to as dynamic characteristics under braking / driving conditions).

  The apparatus 1 includes a CPU 2 that manages and controls the execution of each part of the computer and each program, a memory 4 that stores various conditions and calculation results via the bus 3, and a mouse and a keyboard that inputs various conditions and various information. An input operation system 5 such as an interface 6, an interface 6 for connecting the input operation system 5 to the bus 3, and an output device for displaying processing results of various programs including various conditions and information input screens and simulation results, and printing them out. 7 and a program group 8 having various programs to be described later and realizing the functions of the apparatus 1.

Here, the program group 8 includes a setting program 9, a vehicle running simulation program 10, a “Magic Formula” data / parameter calculation program 11, a tire dynamic model program group 12, and an integration / management program 13. Composed.
The setting program 9 sets data of vehicle specifications and parameter values of “Magic Formula”. The vehicle travel simulation program 10 performs a vehicle travel simulation using a vehicle model. “Magic Formula” data parameter calculation program 11
Given the value of the “Magic Formula” parameter, calculate the characteristic curve data of the dynamic characteristics of the tire under braking / driving conditions. Is calculated. The tire dynamic model program group 12 derives values of a plurality of tire dynamic element parameters (hereinafter referred to as dynamic element parameters) based on a tire dynamic model described later, when a characteristic curve of dynamic characteristics under braking / driving conditions is given. Alternatively, when a value of a dynamic element parameter in the tire dynamic model is given, a characteristic curve of dynamic characteristics of longitudinal force, lateral force, and self-aligning torque (hereinafter referred to as torque) is calculated using the tire dynamic model. The integration / management program 13 integrates control and management of the above program, corrects the value of the “Magic Formula” parameter according to the simulation result, and evaluates the performance of the vehicle from the simulation result.
Here, the characteristic curve of the dynamic characteristics under the braking / driving conditions is a curve representing the lateral force and the slip angle dependency of the torque when the slip ratio in the braking / driving direction and the load load are constant values, or the slip angle and the load. It is a curve showing the slip ratio dependence of the braking / driving direction of a tire when a load is a constant value.
The “Magic Formula” parameter is an approximate expression parameter that defines a nonlinear approximate expression when the characteristic curve of the dynamic characteristic is approximated by the nonlinear approximate expression shown in the above formula (20). The nonlinear approximate expression in the present invention is not limited to “Magic Formula” represented by Expression (20). For example, a nonlinear approximation expression using an exponential function or a polynomial may be used.

The setting program 9 is a part for setting vehicle specification data and “Magic Formula” parameter values. For example, the wheel base, the height of the center of gravity, the total weight of the vehicle, the weight distribution of the front and rear wheels of the vehicle, the suspension characteristics, etc. Are set through the input operation system 5. Alternatively, it is set by calling data stored in the memory 4. The parameter value of “Magic Formula” is set by calling data stored in the memory 4.
The vehicle travel simulation program 10 creates a vehicle model according to the data of the vehicle specifications, calls the travel simulation condition given from the operation input system 5 or the travel condition stored in the memory 4, and creates the generated vehicle model. This is a part for performing a running simulation of a vehicle by assigning a set parameter value. The parameter value is, for example, a set of slip rates and load loads in a plurality of braking / driving directions, and approximates a slip angle-dependent characteristic curve for each slip rate and load load in the braking / driving directions, or A plurality of slip angles and load loads are set, and the characteristic curve of the slip ratio dependency in the braking / driving direction is approximated for each slip ratio and load load in the braking / driving direction.

The vehicle model used for the traveling simulation is a mechanism analysis model, for example, a model created by mechanism analysis software ADAMS. Alternatively, an analysis model defined by the motion analysis software CarSim or the control system design software MatLab may be used.
The traveling simulation conditions include the traveling speed of the vehicle including braking / driving, the steering angle, the profile shape of the road surface, and the like, and different traveling simulation conditions are set according to the performance to be evaluated.
The running simulation is performed by mechanism analysis software ADAMS. Further, the calculation of the running simulation may be performed by the motion analysis software CarSim or the control system design software MatLab.

  The “Magic Formula” data parameter calculation program 11 uses the value of this parameter to set the longitudinal force, lateral force and self-aligning torque according to the above equation (20) when a value is given to the “Magic Formula” parameter. The value is calculated, and the characteristic curves of the longitudinal force, lateral force and self-aligning torque are obtained. For example, when parameter values are given for a plurality of slip rates and load loads in a plurality of braking / driving directions, a longitudinal force, a lateral force and a self force are used for each slip ratio and load loads in the braking / driving directions using these parameters. A characteristic curve of slip angle dependency regarding the aligning torque is obtained. Alternatively, when parameter values are given for each of a plurality of slip angles and a plurality of load loads, these are used to determine the braking / driving direction for the longitudinal force, lateral force, and self-aligning torque for each slip angle and load load. A characteristic curve dependent on the slip ratio is obtained. Further, by using the parameter value, it is possible to obtain a load-dependent characteristic curve of the longitudinal force, the lateral force, and the self-aligning torque when the slip angle in the slip ratio in the braking / driving direction is a constant value of 1 degree.

On the other hand, when the characteristic curves of the longitudinal force, the lateral force and the self-aligning torque are given to the “Magic Formula” data / parameter calculation program 11, the parameter values are obtained from the characteristic curves. The method for obtaining the parameter value is not particularly limited. For example, since Equation (20) is non-linear with respect to the parameter, it is preferably performed according to the Newton-Raphson method. For example, when the characteristic curve is given for each of a plurality of slip rates and a plurality of load loads in the braking / driving directions, a parameter value is obtained for each of the slip rates and load loads in the braking / driving directions. Similarly, when the characteristic curve is given for each of a plurality of slip angles and a plurality of load loads, a parameter value is obtained for each slip angle and each load load.
The tire dynamic model program group 12 will be described in detail later.

  The integration / management program 13 integrates control and management of the above program, and corrects the data of the vehicle specifications and the values of the parameters “B” to “E” of the “Magic Formula” according to the vehicle simulation result. In addition, the vehicle performance is evaluated from the simulation result. When the predetermined evaluation data calculated as performance evaluation does not reach the set target value, the integration / management program 13 sets the evaluation data for the vehicle specification data and the parameter value of “Magic Formula”. Make corrections repeatedly until the target value is satisfied. The correction method is not particularly limited. For example, the data of the vehicle specifications or the parameter value of “Magic Formula” is changed within a predetermined range. When the evaluation data calculated as performance evaluation reaches the set target value, it is derived from the corrected vehicle specification data, the value of the “Magic Formula” parameter, and the value of the “Magic Formula” parameter described later. The dynamic element parameters are determined as design specifications that achieve the desired performance. The mechanical element parameter is determined as a required characteristic of the tire. Such required characteristics of the tire are output to the output device 7.

  The tire dynamic model program group 12 represents a tire dynamic model as an analytical expression, and calculates a longitudinal force, a lateral force, and a torque using the set dynamic element parameter values, a tire dynamic model calculation program 14, and a tire dynamic model calculation A program for deriving values of various mechanical element parameters by causing the program 14 to calculate in a predetermined sequence, or for calculating longitudinal force, lateral force and torque in which the force is balanced (equilibrium) with the tire dynamic model. Including. The values of various mechanical element parameters derived by the tire dynamic model program group 12 or the calculated characteristic curves of longitudinal force, lateral force and torque are configured to be output to the output device 7.

Examples of the dynamic element parameters calculated based on the tire dynamic model are as follows.
(A) the lateral stiffness K _y determined by the lateral shear stiffness of the tire tread portion,
(B) longitudinal rigidity K _x determined by shear rigidity in the longitudinal direction (braking / driving direction) of the tire tread portion;
(C) Torsional rigidity A _y around the tire central axis of the tire tread portion,
(D) Static coefficient μ _s between road surface and tire,
(E) Dynamic coefficient between road surface and tire μ _d (μ _d0 , b _V ),
(F) the transverse bending coefficient ε of the belt member,
(G) Torsional compliance (1 / _Gmz ) which is the reciprocal of torsional rigidity around the tire central axis of the tire,
(H) Coefficient n that defines the contact pressure distribution on the contact surface during the generation of lateral force,
(I) a coefficient C _q representing the degree of deflection of the ground pressure distribution,
(J) a movement coefficient C _xc indicating the degree of movement of the center position of the tire contact surface in the front-rear direction;
(K) The effective contact length l when a lateral force is generated.

Here, the lateral stiffness K _y , the longitudinal stiffness K _x , and the torsional stiffness A _y are respectively the lateral stiffness parameter against the shear deformation of the tire tread portion, the longitudinal stiffness parameter, the tire center axis circumference (the tire center The torsional stiffness parameter about the axis perpendicular to the contact surface), the lateral bending coefficient ε, and the torsional compliance (1 / _Gmz ) _Gmz are the stiffness parameter of the tire against the lateral bending deformation and the tire It is a rigidity parameter with respect to torsional deformation. Further, the lateral direction in which the lateral force is generated means the axial direction of the tire rotation axis. Therefore, the lateral direction when the tire rolls in a straight line state is the left-right direction with respect to the rolling direction, and the direction coincides. However, when the slip angle is added, the lateral direction is the slip angle with respect to the rolling direction of the tire. I can't tell. The front-rear direction refers to a direction that is parallel to the road surface on which the tire contacts and that is orthogonal to the axial direction of the rotation axis of the tire. Further, the tire center axis (referred to as the axis CL in FIGS. 6A and 6B) is perpendicular to the road surface perpendicular to the rotation axis of the tire and passing through the center plane in the tire width direction. Is the axis.

The tire dynamic model program group 12 has four different types of sequences. Corresponding to each sequence, a small slip angle condition parameter calculation program 20, an _Fx / _Fy / _Mz parameter calculation program 22, a small slip angle condition _Fx / _Fy / _Mz data calculation program 24, And F _x / F _y / M _z data calculation program 26.
The small slip angle condition parameter calculation program 20 determines the value of the dynamic element parameter from the load dependency curves of the longitudinal force, lateral force, and self-aligning torque when the slip angle is 1 degree. The F _x / F _y / M _z parameter calculation program 22 determines the value of the dynamic element parameter from the characteristic curves of the applied longitudinal force, lateral force and self-aligning torque. The small slip angle condition F _x / F _y / M _z data calculation program 24 obtains calculation data of longitudinal force, lateral force, and self-aligning torque at a slip angle of 1 degree in a state of force balance in the tire dynamic model. The F _x / F _y / M _z data calculation program 26 obtains calculation data of longitudinal force, lateral force, and torque in a state of balance of force in the tire dynamic model.
The small slip angle condition parameter calculation program 20, the F _x / F _y / M _z parameter calculation program 22, the small slip angle condition F _x / F _y / M _z data calculation program 24 and the F _x / F _y / M _z data More detailed functions of the calculation program 26 will be described later.

When the longitudinal force, lateral force and torque values of the characteristic curve are input to the tire dynamic model calculation program 14, the corresponding calculation data (front / rear force F _x ′, lateral force F) calculated by the tire dynamic model using these values. _y ′ and torque M _z ′) are output as processing results, small slip angle condition parameter calculation program 20, F _x / F _y / M _z parameter calculation program 22, and small slip angle condition F _x / F _y / M _z data. This is a calculation unit that returns to the calculation program 24 or the F _x / F _y / M _z data calculation program 26. The longitudinal force, lateral force and torque values of the characteristic curve input to the tire dynamic model calculation program 14 are the values of the “Magic Formula” parameters set in the setting program 9 or the integration / management program 13. This is calculated using the corrected “Magic Formula” parameter values.
2, 3, 4, 5 (a) to 5 (e), 6 (a) to (d), 7 (a) to (c), and FIG. 8 are diagrams illustrating a tire dynamic model. is there.

  As shown in FIG. 2, the tire dynamic model includes a sidewall model composed of a plurality of spring elements representing the spring characteristics of the sidewalls on a rigid cylindrical member, and a belt model composed of an elastic ring body connected to these spring elements. And a tread model composed of an elastic element representing a tread model connected to the surface of the elastic ring body.

More specifically, in the tire dynamic model determined by the tire dynamic element calculation program 14, the following processing is performed. FIG. 3 shows the processing contents when the slip ratio S in the braking / driving direction is braking, and FIG. 4 shows the processing contents when the slip ratio S in the braking / driving direction is driving.
In the case of braking, as shown in FIG. 3, the values of dynamic element parameters including linear parameters such as lateral stiffness K _y and torsional stiffness A _y and nonlinear parameters such as lateral bending coefficient ε and coefficient C _{q of the} belt member are set. By inputting the slip angle α, the slip ratio S during braking, the tire traveling speed V _r , the longitudinal force F _x , the lateral force F _y , and the torque M _z , the equations (1) to (8) in FIG. ) To calculate the longitudinal force, lateral force, and torque values (hereinafter referred to as longitudinal force F _x ′, lateral force F _y ′, and torque M _z ′) processed by (). Of course, an error between the input longitudinal force F _x , lateral force F _y and torque M _z and the processed longitudinal force F _x ′, lateral force F _y ′ and torque M _z ′ is less than a predetermined value. That is, the values of the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ realize the force balanced state only when they are substantially coincident (converged and the force is balanced in the tire dynamic model). This is determined as the value of the longitudinal force, lateral force, and torque of the tire.
The linear parameter means a dynamic element parameter expressed in a linear form in the equations (6) to (8), and the nonlinear parameter is expressed in a non-linear form in the equations (6) to (8). It is a dynamic element parameter.

The tire dynamic element calculation program 14 is shown in FIG. 5 (a), and further, as shown in the equation (1), the torsion return angle determined by the input torque _Mz and torsional compliance (1 / _Gmz ). is calculated, the twist back angle by subtracting from the slip angle alpha granted, to calculate the effective slip angle alpha _e. The reason why the effective slip angle α _e is calculated in this manner is that when the torque M _z is larger than 0, the torque acts on the tire itself so as to reduce the applied slip angle, and has a function of twisting back. . Therefore, when the torque M _z is larger than 0, as shown in FIG. 5A, the effective slip angle α _e becomes smaller than the actually applied slip angle α.

Furthermore, by the equation (2) to calculate the bias coefficient q defining the shape of the contact pressure distribution from the longitudinal force F _x. The bias coefficient q, contact pressure distribution of the straight traveling state of the slip angle alpha = 0 (see FIG. 6 (a)), progress ground pressure distribution longitudinal force F _x is generated as shown in FIG. 6 (b) This is a parameter representing the shape of the contact pressure distribution deflected toward the front in the direction (the stepping end on the contact surface). This contact pressure distribution is represented by p (t) (where t is the coordinate position normalized by the contact length when the t-axis is taken in the backward direction of travel in FIGS. 6A and 6B). Then, the shape of the ground pressure distribution p (t) is defined by the function D _gsp (t; n, q) represented by the equation (9) in FIG.
Here, the coefficient n in the function D _gsp (t; n, q) defines the contact pressure distribution of the contact surface during the generation of the lateral force. As shown in FIG. And a coefficient that regulates the contact pressure distribution so that it is angular (the curvature increases) in the vicinity of the kicking edge. Further, as shown in FIG. 6D, the peak position of the contact pressure distribution is set so as to move toward the stepping-end side as the coefficient q is changed from 0 to 1. Thus, the coefficient q and the coefficient n are shape defining coefficients that define the shape of the contact pressure distribution.

Further, the amount by which the center position of the tire contact surface moves in the front-rear direction due to the generation of the front-rear force F _x is calculated from the equation (3). As shown in FIG. 5C, a value (x _c / l) representing the degree to which the ground contact center position of the tire moves in the front-rear direction when the front-rear force F _x is generated is determined according to the formula (3). Calculated in association with F _x . That is, when a slip ratio in the braking / driving direction is given, the position of the ground contact surface according to the generated longitudinal force is such that the position of the ground contact surface with respect to the road surface of the tire moves in the longitudinal direction due to the longitudinal force generated as the tire axial force. The tire dynamic model is configured so that the center position moves. This amount of movement (x _c / l) is used in the second term of equation (8) for calculating torque M _z described later. Here, l is the contact length. In this way, the movement of the center position of the ground contact surface of the tire is defined in the equation (3) because the tire deformation in the vicinity of the ground contact during tire braking is actually applied during braking and driving as shown in FIG. This is because the shape of the tire in the vicinity of the ground contact surface is different from each other and the ground contact center position is moved by braking / driving. FIG. 5 (d) is a diagram showing an actual measurement result obtained by measuring a tire shape of 195 / 65R15 91H (internal pressure 230 kPa, load 4 kPa, traveling speed 60 km / hour) with a laser scanner.

Further, according to the equation (4), the boundary position (l _h / l) between the sliding friction and the adhesion friction in the contact surface that occurs when the slip ratio (the slip ratio S and the slip angle α in the braking / driving direction) is large is obtained. Calculated. The boundary position (l _h / l) is defined as follows.
The maximum friction curves shown in FIGS. 7A to 7C are obtained by multiplying the adhesion friction coefficient _μs by the contact pressure distribution p (t). The tread member of the tire that is in contact with the road surface at the stepping end is gradually sheared laterally from the road surface by the slip angle α as it moves to the kicking end, and a lateral shearing force (adhesion frictional force) is generated on the tread member. To do. Further, the tread member is gradually sheared in the longitudinal direction from the road surface by the slip ratio S in the braking / driving direction caused by the difference between the road surface moving speed (tire traveling speed) and the tire rotational speed, and the tread member is sheared in the longitudinal direction. Force (adhesion frictional force) is generated. The shearing force generated between the tire and the road surface is represented by the resultant force of the lateral shearing force and the longitudinal shearing force.
Resultant of the shear forces, reaching the maximum friction curve gradually increases, tire tread elements which have adhesion to the road surface Suberidashi, sliding friction multiplied by the contact pressure distribution p (t) sliding friction coefficient mu _d A sliding friction force is generated according to the curve. In FIG. 7 (a), the region at the stepping end side from the boundary position (l _h / l) is an adhesion region in which the tire tread member is adhered to the road surface, and the region on the kick-out side is the tire tread member with respect to the road surface. It will be a sliding area. The boundary position (l _h / l) is determined by equation (4).

The slip angle α can be expressed in the same dimensionless unit as the slip ratio S in the braking / driving direction by representing the slip ratio tanα in the lateral direction, and is integrated as a slip ratio together with the slip ratio S in the braking / driving direction. can do. In the following description, a description will be given mainly using the slip angle α in place of the slip rate obtained by integrating the slip rate S in the braking / driving direction and the slip angle α.
FIG. 7B shows a state where the slip angle α is larger than the slip angle α shown in FIG. The boundary position (l _h / l) has moved to the stepping end side as compared with FIG. Furthermore, when the slip angle α increases, as shown in FIG. 7C, a sliding friction is generated from the position of the stepping end of the ground contact surface.

As can be seen from FIGS. 7A to 7C, the ratio of the adhesion region to the slip region varies greatly depending on the slip angle α. The lateral force F _y ′ can be calculated by integrating the lateral frictional force in the adhesion region and the sliding region, that is, the lateral force component along the tire width direction, and the moment around the tire center O can be calculated. By calculating, the torque M _z ′ can be calculated.
Similarly, also in the front-rear direction, the front-rear force F _x ′ can be calculated by integrating the front-rear direction frictional force in the adhesion region and the slip region, that is, the front-rear force component along the tire width direction.
In the equation (6), the longitudinal force F _x ′ is calculated separately for the above-mentioned adhesion region and the slip region, and in the equations (7) and (8), the lateral force F _y ′ is calculated using the effective slip angle α _e. And torque M _z ′ is calculated.
The sliding friction coefficient μ _d is defined to have a sliding speed dependency (the second term on the right side of Expression (5)) as shown in Expression (5). The coefficient representing the slip speed dependency changes according to the slip angle α and the slip ratio S in the braking / driving direction.

FIGS. 5A to 5C schematically show the ground contact surface with respect to the effective slip angle α _e , the relaxed adhesion lateral force component generated by the deformation of the belt, and the movement of the ground contact surface center position. It is the behavior represented by the formulas (6) to (8).
In FIG. 5A, as described above, when the slip angle α is applied, the tire itself acts so as to reduce the slip angle α by the torque generated by the slip angle α, and the effective slip angle α _e is obtained. Indicates the state. FIG. 5 (b) shows the relationship between the lateral displacement caused by the lateral bending deformation of the lateral displacement and the belt caused by the effective slip angle alpha _e. FIG.5 (c) has shown that the contact surface of a tire moves to the front-back direction with the front-back force.

Next, equations (6) to (8) will be described in more detail.
Equation (6) calculates the longitudinal force F _x ′ by the sum of two terms (two longitudinal force components). The first term is an integration result in an integration range of 0 to (l _h / l), and represents an adhesion longitudinal force component generated in the adhesion region. The second term is an integral having an integration range of (l _h / l) to 1, and represents a slip longitudinal force component generated in the slip region.
In equation (7), the lateral force F _y ′ is calculated by the sum of two terms (two lateral force components). The first term is an integral having an integration range of 0 to (l _h / l), and represents an adhesion lateral force component generated in the adhesion region. The second term is an integral having an integration range of (l _h / l) to 1, and represents a slip lateral force component generated in the slip region. Adhesive lateral force component of the first term in equation (7) is a lateral force in the adhesive region, in Formula (7), lateral transverse displacement of the belt tread element caused by the effective slip angle alpha _e bending deformation The adhesion lateral force component is calculated by expressing the state relaxed by. The sliding lateral force component of the second term is a lateral force in the sliding region. In the equation (7), the shape of the contact pressure distribution p (t) generated by the effective slip angle α _e is expressed by the function D _gsp (t; n, q). The sliding lateral force component is calculated by

In Equation (8), the first term is an integral with an integration range of 0 to (l _h / l), and represents the torque component generated by the adhesion lateral force component generated in the adhesion region, and the second term. Is an integral with an integration range of (l _h / l) to 1 and represents a torque component generated by a slip lateral force component generated in the slip region. In the equation (8), in addition to the two torque components, another torque component, that is, a third term is provided. The third term is a term proportional to (l _h / l) · tan α _e , and the tire contact surface is moved laterally by the slip angle α, and the tire generated by the amount of movement at this time and the longitudinal force generated on the tire. This represents the torque component around the central axis. That is, the torque M _z ′ is calculated based on a torque component generated by an adhesion lateral force, a torque component generated by a sliding lateral force, a torque component generated by an adhesion longitudinal force, and a torque component generated by a sliding longitudinal force.

Regarding the sliding friction coefficient μ _d in the sliding region, the same sliding friction coefficient is used in the formula (6) for calculating the longitudinal force and the formula (7) for calculating the lateral force, but the sliding friction coefficient varies depending on the tread pattern. Moreover, you may treat as a different parameter in Formula (6) and Formula (7).
Further, β used in the equations (6) to (8) represents an angle in the sliding direction in the sliding area of the ground contact surface during braking / driving, and is determined by the slip angle and the slip ratio in the braking / driving direction. Since the frictional force acts on this sliding direction, in Equation (6), the cosine component of the longitudinal force relative to the sliding direction, in Equation (7) the sin component of the lateral force relative to the sliding direction, and in Equation (8) the torque The sin component of the contributing lateral force contributes to the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′, respectively. That is, the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ are calculated using the angle β in the sliding direction.
The slip direction in the slip region does not necessarily result in the slip angle α direction and the braking / driving direction because the slip in the braking / driving direction and the slip by the slip angle α occur simultaneously. Specifically, as shown in FIG. 5 (e), different running speed V _w and the direction of the rotational velocity V _r of the tires, the difference in this orientation, the slip velocity V _s, the slip direction of the angle β Determined. The angle β in the sliding direction at this time is defined in parentheses in the expressions (6) to (8) and the expressions (16) to (18). The definition of β in the equations (6) to (8) and the equations (16) to (18) is different because the definition of the slip ratio S in the braking / driving direction during braking and during driving is different as described later.

In the case of braking, as shown in FIG. 4, as in the case of braking, dynamic element parameters including linear parameters and nonlinear parameters are set, and the slip angle α, the slip ratio S in the braking / driving direction, and the tire traveling speed are set. By inputting V _r , longitudinal force F _x , lateral force F _y , and torque M _z , the longitudinal force, lateral force, and torque values processed by the equations (11) to (18) in FIG. , The longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′) are calculated. Of course, an error between the input longitudinal force F _x , lateral force F _y and torque M _z and the processed longitudinal force F _x ′, lateral force F _y ′ and torque M _z ′ is less than a predetermined value. That is, the values of the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ realize the force balanced state only when they are substantially coincident (converged and the force is balanced in the tire dynamic model). It is determined as the value of the lateral force and torque of the tire.
Although each of Formula (14), Formula (15), and Formulas (16) to (18) is different from Formula (4), Formula (5), and Formulas (6) to (8) in FIG. Is due to the difference in definition of slip ratio. Specifically, the slip ratio S during braking is defined by S = (V _r cos α−V _w ) / V _r cos α (tire running speed V _r , tire rotational speed V _w , slip angle α), The slip ratio S during driving is defined by S = (V _r cos α−V _w ) / V _w . For this reason, when considering the force generated in the tire, the tire side moving speed (the denominator on the right side in the above definition) defined by the slip ratio is different, and therefore the expressions (14), (15), and (16) Each of (18) is different from the expressions (4), (5), and (6) to (8) in FIG. Other expressions are the same as the corresponding expressions in FIG. Therefore, explanation of these equations is omitted.

FIG. 8 is a processing block diagram until the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ are calculated based on the tire dynamic model with the slip angle α and the slip ratio S in the braking / driving direction applied. is there. As can be seen from FIG. 8, the tire dynamic model according to the present invention is such that when calculating the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′, the lateral bending deformation of the belt, the contact pressure distribution, and the center of the contact surface. Each of the change in position and the torsional deformation of the tire is fed back and calculated by the equations (6) to (8) or the equations (16) to (18). Note that the lateral bending deformation of the belt, the change in the contact pressure distribution and the center position of the contact surface, and the torsional deformation of the tire used for calculating the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ The applied longitudinal force F _x and lateral force F _y are used.

Note that the longitudinal force F _x ′, lateral force F _y ′, and torque M _z ′ calculated in the tire dynamic model calculation program 14 do not necessarily match the applied longitudinal force F _x , lateral force F _y, and torque M _z. . However, the longitudinal force F _x , the lateral force F _y and the torque M _z which are applied and the longitudinal force F _x ′, the lateral force F _y ′ and the torque which are calculated by the sequence processing performed in the tire dynamic model program group 12 which will be described later. The longitudinal force F _x , the lateral force F _y, and the torque M _z are searched so that M _z ′ substantially coincides (becomes a force balanced state), and the longitudinal force, lateral force, and Torque is calculated.

Next, the small slip angle condition parameter calculation program 20, the F _x / F _y / M _z parameter calculation program 22, the small slip angle condition F _x / F _y / M _z data calculation program 24, F _x / F _y / M The function of the _z data calculation program 26 will be described.
The small slip angle condition parameter calculation program 20 includes a longitudinal force F _x and a lateral force at a slip angle of 1 degree determined by using the value of the “Magic Formula” parameter set or corrected in the “Magic Formula”. When the characteristic curves of F _y and torque M _z are supplied, the longitudinal force F _x , the lateral force F _y and the torque M _z , the longitudinal force F _x ′ calculated by the tire dynamic model calculation program 14, and the lateral force F The linear and non-linear parameters described above are set so that the error between _y ′ and torque M _z ′ is not more than a predetermined value, that is, so that the longitudinal force, lateral force and torque are balanced in the tire dynamic model. This is a program to derive. The characteristic curve at the slip angle α = 1 degree is supplied for each load ratio and slip ratio S in the braking / driving direction.

FIG. 8 shows the flow of processing performed in the small slip angle condition parameter calculation program 20.
Specifically, the data on the longitudinal force F _x , the lateral force F _y and the torque M _z of the characteristic curve at the slip angle α = 1 degree, and the ground contact of the tire in the non-rolling state at the load load F _z and the load load F _z . Data of the length l and the contact width w is acquired in advance (step S100). These data are data stored in the memory 4 and are called from the memory 4. Alternatively, an instruction input from the input operation system 5 may be used.
Furthermore, non-linear parameters such as the lateral bending coefficient ε and torsional compliance (1 / G _mz ) are initially set to predetermined values (step S102).

Next, the values of linear parameters are calculated by linear square regression, which is a known technique, using the initial set values of the lateral bending coefficient ε and torsional compliance (1 / G _mz ) (step S104).
Here, since the nonlinear parameter is set to a predetermined value, a normal equation for the linear parameter can be determined, and the value of the linear parameter can be uniquely calculated by solving the normal equation. Specifically, the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ calculated by the equations (6), (7), and (8) are the supplied longitudinal force F _x , A normal equation related to the linear parameter is created from the equation of the sum of squared residuals using the set nonlinear parameter so as to optimally return to the lateral force F _y and the torque M _z, and by solving this normal equation, Calculate the value. Here, the normal equation is an equation for partial differentiation of an equation for determining the residual sum of squares with respect to each linear parameter and setting the partial differential value to 0, and is an equation relating to the linear parameter created by the number of linear parameters. .

Next, the supplied data of the longitudinal force F _x , the lateral force F _y and the torque M _z , the calculated linear parameters, and the initialized nonlinear parameters are given to the tire dynamic model calculation program 14. In the tire dynamic model calculation program 14, the longitudinal force F _x , lateral force F _y, torque M _z data, linear parameters, and non-linear parameters are applied to the front and rear at the slip angle α = 1 degree according to the flow of the processing block diagram shown in FIG. A force F _x ′, a lateral force F _y ′, and a torque M _z ′ are calculated. In this case, since the slip angle α is 1 degree, the ground pressure distribution coefficient n of the ground pressure distribution at the slip angle α = 0 degree is fixed, and the deflection coefficient q is set to 0. Furthermore, the boundary position (l _h / l) between the adhesion area and the sliding area is set to 1. That is, there is no slip area on the ground contact surface, and all are adhesion areas. Therefore, the slip longitudinal force component, the slip lateral force component, and the torque component generated by the slip lateral force component in the equations (6) to (8). Becomes 0. Further, since the contact length l is given as the measurement data, the function of the contact length and regression exponential function of the measured contact length l of the applied load F _z, i.e., a function having the applied load F _z dependence is used .

  Here, the ground contact width w is the width in the lateral direction of the tread portion of the tire, and a tire groove that forms a tread pattern is provided in the tread portion. For this reason, since the actual ground contact area actually in contact with the road surface is different from the total ground contact area of the tread member, the ground contact width w corrected using the ratio of actual ground contact area / total ground contact area is used.

Next, the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′, which are the corresponding calculation data of the longitudinal force, lateral force and torque at the slip angle α = 1 degree calculated by the tire dynamic model calculation program 14, are as follows. Is returned to the small slip angle condition parameter calculation program 20, and the calculated data of the longitudinal force _Fx ', the lateral force _Fy ' and the torque _Mz ', the longitudinal force _Fx and the lateral force F at the slip angle α = 1 degree. Using the data of _y and torque M _z , a composite square residual sum Q _c represented by the following equation (19) is calculated (step S106).

Here, N is the number of conditions set for the load load and the slip ratio S in the braking / driving direction, and i is an integer from 1 to N. Further, g _x, g _y and _{g m} is the longitudinal force _{F x,} the lateral force _{F y} and _the torque _{M z} longitudinal force _{F x} in the N condition for the data of the dispersion of the lateral force _{F y} and _the torque _{M z} sigma _{When x} ² , σ _y ^2, and σ _m ² , the coefficients are expressed by the following formulas, and are weighting coefficients used when obtaining the composite square residual sum Q _c .
g _x = 1 / σ _x ²
g _y = 1 / σ _y ²
g _m = 1 / σ _m ²
That is, the composite square residual sum Q _c is obtained by weighting and adding the square residual sums of the longitudinal force, the lateral force, and the torque with the reciprocal of the variance, which is information on the dispersion of the characteristic curve values, as a weighting coefficient. .

As described above, the sum of squared residuals of the value of the longitudinal force F _x of the measurement data and the value of the longitudinal force F _x ′ of the calculated data is multiplied by the weighting coefficient g _x , the value of the lateral force F _y and the calculated data. The residual sum of squares of the value obtained by multiplying the sum of squared residuals with the value of the lateral force F _y ′ by the weighting coefficient g _f and the value of the torque M _z of the measured data and the value of the torque M _z ′ of the calculated data The composite square residual sum is calculated by adding the weighted coefficient g _m multiplied by the sum.
Here, the composite sum of squared residuals is used to calculate the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ of a plurality of conditions in the calculation of the nonlinear parameter, and the corresponding longitudinal force F _x and lateral force. This is for optimally matching _Fy and torque _Mz .

Further, it is determined whether or not the composite square residual sum is equal to or less than a predetermined value (step S108).
If it is determined that it has not converged, the previously set nonlinear parameter value is adjusted (step S110). Adjustment of the value of this nonlinear parameter is performed, for example, according to the Newton-Raphson method. Specifically, an equation relating the matrix and the adjustment amount of the nonlinear parameter is obtained by performing a second-order partial differentiation of the composite square residual sum with respect to the nonlinear parameter, and the equation is solved with respect to the adjustment amount. The amount of adjustment of the nonlinear parameter value is calculated. This calculation method is described in detail in Japanese Patent Application No. 2001-242059 (Japanese Patent Laid-Open No. 2003-57134) filed by the applicant of the present application.

Each time the value of this nonlinear parameter is adjusted, linear least square regression (step S104) and calculation of a composite square residual sum (step S106) regarding the linear parameter are performed to obtain a composite square residual sum according to equation (19). . Then, the adjustment of the value of the nonlinear parameter is repeated until the composite square residual sum becomes a predetermined value or less.
When the composite square residual sum becomes equal to or less than a predetermined value, the value of the linear parameter and the value of the nonlinear parameter calculated by the linear least square regression are determined as parameters (step S112). The parameter value is determined for each supplied condition. The determined parameter value is stored in the memory 20. Alternatively, the parameter value is output to the output device 7.
The flow of calculation of the linear parameter and the nonlinear parameter at the slip angle α = 1 degree using the tire dynamic model performed by the small slip angle condition parameter calculation program 20 has been described above.

Next, the F _x / F _y / M _z parameter calculation program 22 will be described.
FIG. 10 shows the flow of processing performed in the F _x / F _y / M _z parameter calculation program 22.
As shown in FIG. 10, first, the F _x / F _y / M _z parameter calculation program 22 is set to a slip angle of 0 to 20 under a plurality of conditions in which the slip ratio in the braking / driving direction is variously changed under a constant load. The characteristic curves of the longitudinal force F _x , the lateral force F _y and the torque M _z when the degree is changed are supplied and acquired (step S202). Alternatively, the longitudinal force F _x , lateral force F _y, and torque M when the slip ratio in the braking / driving direction is changed in the range of −1 to 1 under a plurality of conditions in which the slip angle is variously changed under a constant load. A characteristic curve of _z is supplied and acquired.
Next, the lateral bending coefficient ε, torsional compliance (1 / G _mz ), coefficient n, etc., which are nonlinear parameters, are initially set to predetermined values (step S204).

Next, linear least square regression is performed using the characteristic curves of the longitudinal force F _x , the lateral force F _y and the torque M _z and the initially set nonlinear parameters (step S206). Specifically, a normal equation regarding linear parameters such as a sliding friction coefficient μ _d0 and a coefficient b _{v at} a sliding speed of 0 is created, and the value of the linear parameter is calculated by solving this normal equation. That is, linear least square regression is performed. Here, as described above, the normal equation is an equation related to linear parameters created by the number of linear parameters in which the residual sum of squares is partially differentiated with respect to each of the linear parameters and the partial differential value is zero.
The tire dynamic model calculation program 14 is provided with the nonlinear parameter values thus initialized and the linear parameter values calculated using the normal equations and the characteristic curves of the longitudinal force F _x , lateral force F _y and torque M _z. To do. With this provision, the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′, which are corresponding calculation data, are calculated according to the flow of the block diagram of FIG.

Next, the calculated data of the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ and the characteristic curves of the longitudinal force F _x , the lateral force F _y, and the torque M _{z at} the applied slip angle α are shown. using the data to calculate the combined sum of squared residuals _{Q c} represented by the above formula (19) (step S208). In this case, N in the equation (19) is the condition setting number of the slip ratio S and slip angle α in the braking / driving direction to be given. Further, the weighting coefficients g _x , g _y , and g _{m at} this time are obtained from variances of the longitudinal force F _x , the lateral force F _y , and the torque M _z under N conditions.

Further, g _x, g _y and _{g m} is the longitudinal force _{F x,} the lateral force _{F y} and _the torque _{M z} longitudinal force F _x in the N condition for the data of the dispersion of the lateral force _{F y} and _the torque _{M z} sigma _{When x} ² , σ _y ^2, and σ _m ² , the coefficients are expressed by the following formulas, and are weighting coefficients used when obtaining the composite square residual sum Q _c .
g _x = 1 / σ _x ²
g _y = 1 / σ _y ²
g _m = 1 / σ _m ²
That is, the composite square residual sum Q _c is obtained by weighting and adding the square residual sums of the longitudinal force, the lateral force, and the torque with the reciprocal of the variance, which is information on the dispersion of the characteristic curve values, as a weighting coefficient. .

Thus, as obtained by multiplying the residual square weighting factor to the sum g _x and the value of the longitudinal force F _x 'calculated by the values and the tire dynamic model computation program 14 of the characteristic curve of _the longitudinal force F _{x, the} lateral and multiplied by the residual weighting factor g _y to the square sum of the value of the calculated at the value of the characteristic curve of the force F _y and tire dynamic model computation program 12 lateral force F _{y ',} the characteristic curve of the torque M _z Is added to the sum of the squares of the residuals of the torque M _z ′ calculated by the tire dynamic model calculation program 14 and the weighting coefficient g _m to calculate a composite square residual sum. Here, similar to the above-mentioned case, the composite square residual sum is used in the calculation of the nonlinear parameter in the longitudinal force F _x ′ and the lateral force F _y ′ under the condition of a plurality of slip angles and the slip ratio in the braking / driving direction. This is because the torque M _z ′ and the longitudinal force F _x , the lateral force F _y, and the torque M _z are simultaneously matched.
It is determined whether or not the composite square residual sum is equal to or less than a predetermined value (step S210).
If it is determined that it has not converged, the nonlinear parameter initially set in step S204 is adjusted (step S212). The adjustment of the nonlinear parameter is performed according to, for example, the Newton-Raphson method.

  The nonlinear parameter is adjusted until it is determined that it converges in step S210. Each time this adjustment is performed, linear least square regression (step S206) and calculation of a composite square residual sum (step S208) regarding the linear parameter are performed. Then, the composite residual sum of squares according to the above equation (19) is obtained. Then, the non-linear parameter adjustment is performed until the composite square residual sum becomes a predetermined value or less. When the composite square residual sum becomes a predetermined value or less, the values of the respective nonlinear parameters calculated by the linear least square regression are determined (step S214), and the values of these dynamic element parameters are stored in the memory 4. Alternatively, the parameter value is output to the output device 7.

The initial setting of the nonlinear parameter value in step S202 in FIG. 10 may be performed by setting the nonlinear parameter value obtained as a result of the processing shown in FIG. 9 as an initial value, or a parameter whose value is undetermined. The initial value may be set independently. However, if the value of the nonlinear parameter is calculated in the process shown in FIG. 9, it is preferable to use the calculated value. This is because the value of the dynamic element parameter obtained by the small slip angle condition parameter calculation program 20 and the value of the dynamic element parameter obtained by the F _x / F _y / M _z parameter calculation program 22 are matched.
The above is a flow of calculation of the values of the linear parameter and the nonlinear parameter using the tire dynamic model performed in the F _x / F _y / M _z parameter calculation program 22.

The small slip angle condition F _x / F _y / M _z data calculation program 24 fixes the slip angle α to 1 degree and the slip ratio S in the braking / driving direction to a constant value, and changes the load load before and after. This is a part for calculating data of force F _x ′, lateral force F _y ′, and torque M _z ′. Further, the slip angle α is fixed to 1 degree, the load is fixed to a constant value, and the slip ratio S in the braking / driving direction is changed to change the longitudinal force F _x ′, lateral force F _y ′, and torque M _z ′. Data can also be calculated.
FIG. 11 shows a case where the data of the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ are calculated by changing the applied load in the small slip angle condition F _x / F _y / M _z data calculation program 24. The flow of processing is shown.

Specifically, as shown in FIG. 11, the small slip angle condition F _x / F _y / M _z data calculation program 24 first calculates linear parameters and nonlinear parameters calculated by the small slip angle condition parameter calculation program 20. The value is read from the memory 4 and set (step S300). The parameter value is set for each load.
Furthermore, the longitudinal force _{F x} under the applied load _{F z,} the lateral force _{F y} and _the torque _{M z} is initialized (step S302).
Thereafter, the linear parameter and the non-linear parameter are given to the tire dynamic model calculation program 14 together with the slip angle α = 1 degree and the initial set longitudinal force F _x , lateral force F _y and torque M _z . The tire dynamic model calculation program 14 uses the given linear and nonlinear parameters, and the initially set longitudinal force F _x , lateral force F _y, and torque M _{z and} uses equations (6) to (8) in FIG. ) Or the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ are calculated according to the equations (16) to (18) in FIG. 4 (step S304).

  In this case, since the slip angle α is 1 degree, the ground pressure distribution coefficient n of the ground pressure distribution at the slip angle α = 0 degree is fixed, and the deflection coefficient q is set to 0. When the contact length l is given, the contact length l is used as a default value.

The longitudinal force F _x ′, lateral force F _y ′ and torque M _z ′ calculated in this way at a slip angle of 1 degree are returned to the small slip angle condition F _x / F _y / M _z data calculation program 24. The small slip angle condition F _x / F _y / M _z data calculation program 24 is a set value of the longitudinal force F _x , lateral force F _y and torque M _z applied to the tire dynamic model calculation program 14 and the calculated longitudinal force F. The composite square residual sum with the calculated values of _x ′, lateral force F _y ′, and torque M _z ′ is calculated according to equation (19) (step S306).

Next, it is determined whether or not the composite square residual sum is equal to or less than a predetermined value (step S308).
If it is determined that it has not converged, the previously set lateral force F _y and torque M _z set values are adjusted (step S310). The adjusted longitudinal force F _x , lateral force F _y and torque M _z are provided to the tire dynamic model calculation program 14 together with the linear parameter and the nonlinear parameter.
Thus, the set values of the longitudinal force F _x , the lateral force F _y and the torque M _z are adjusted until the composite square residual sum becomes a predetermined value or less and converges. This set value is adjusted, for example, according to the Newton-Raphson method described above. Thus, the converged longitudinal force F _x ′, lateral force F _y ′, and torque M _z ′ are determined (step S312).

Furthermore, the conditions of _the applied load _{F z} is changed (step S314). Each time the applied load F _z is changed, the longitudinal force F _x , the lateral force F _y and the torque M _z are initially set (step S302), and the longitudinal force F _x 'and the lateral force F _y ' are set using these set values. And the torque M _z ′ are calculated (step S304), the composite square residual sum is calculated (step S306), and the convergence of the composite square residual sum is determined (step S308).
Thus, changes in sequence constant direction applied load F _z, repeatedly changed until the predetermined load (step S316). Every time the applied load F _z is changed, the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ are calculated, and the convergent longitudinal force F _x ′, lateral force F _y ′, and torque M _z ′ are determined. . The determined longitudinal force F _x ′, lateral force F _y ′ and torque M _z ′ are stored in the memory 20.
Thus, the slip ratio S of the braking-driving direction a predetermined value, obtains the curve at the slip angle alpha = 1 degree dependent on the applied load F _z. Of course, it is also possible to obtain a curve at the slip angle α = 1 degree depending on the slip ratio S in the braking / driving direction with the load _Fz being a constant value.
The above is the flow of processing using the tire dynamic model performed in the small slip angle condition F _x / F _y / M _z data calculation program 24.

The F _x / F _y / M _z data calculation program 26 uses a linear parameter and a non-linear parameter, which are tire dynamic element parameters in the tire dynamic model, at a predetermined load, to calculate the slip ratio and slip angle in the braking / driving direction. This is a part for calculating data of longitudinal force, lateral force, and torque while fixing one to a constant value. For example, the characteristic curve when the slip angle α is changed from 0 to 20 degrees with the slip ratio S in the braking / driving direction as a constant value is obtained, or the slip ratio S in the braking / driving direction is determined with the slip angle α as a constant value. The characteristic curve when changing in the range of −1 to 1 is obtained, or the slip ratio S and the slip angle α in the braking / driving direction are freely changed, the vertical axis is the lateral force, and the horizontal axis is the longitudinal force. Find the friction ellipse.

FIG. 12 shows an example of the flow of processing performed in the F _x / F _y / M _z data calculation program 26. This example is an example in which the characteristic curve representing the dependence of the longitudinal force, lateral force and torque on the slip angle α is calculated with the slip ratio S and the load applied in the braking / driving direction fixed to constant values.
The F _x / F _y / M _z data calculation program 26 first reads and sets the derived linear parameter value and nonlinear parameter value from the memory 4 (step S400).
Furthermore, the longitudinal force _{F x} under the applied load F _z, the lateral force _{F y} and _the torque _{M z} is initialized (step S402).
Thereafter, when calculating a characteristic curve representing the slip angle dependency, the linear and non-linear parameters, the initial longitudinal force F _x , the lateral force F _y and the torque M _z are set with the set slip angle α = Δα. The dynamic model calculation program 14 is given. In the tire dynamic model calculation program 14, the given linear and non-linear parameters and the initial longitudinal force F _x , lateral force F _y, and torque M _z are used to formula (6) to (8) or formula ( The longitudinal force F _x ′, lateral force F _y ′, and torque M _z ′ are calculated according to 16) to (18) (step S404).

The longitudinal force F _x ′, lateral force F _y ′, and torque M _z ′ thus calculated are returned to the F _x / F _y / M _z data calculation program 26. The F _x / F _y / M _z data calculation program 26 is a set value of the longitudinal force F _x , lateral force F _y and torque M _z given to the tire dynamic model calculation program 14 and the calculated longitudinal force F _x ′, lateral force. A compound square residual sum with the calculated values of force F _y ′ and torque M _z ′ is calculated according to equation (19) (step S406).
Next, it is determined whether or not the calculated composite square residual sum is equal to or smaller than a predetermined value (step S408).
If it is determined that it has not converged, the set values of the longitudinal force F _x , lateral force F _y and torque M _z set previously are adjusted (step S410). The adjusted longitudinal force F _x , lateral force F _y, torque M _z , linear parameters and non-linear parameters are provided to the tire dynamic model calculation program 14 again.

In this manner, the set values of the longitudinal force F _x , the lateral force F _y and the torque M _z are adjusted until the composite square residual sum becomes a predetermined value or less and converges. This set value is adjusted, for example, according to the Newton-Raphson method described above. Thus, the longitudinal force F _x ′, the lateral force F _y ′, and the torque M _z ′ are determined (step S412).

Next, it is determined whether or not the slip angle α is equal to or smaller than a predetermined slip angle (step S416).
When it is determined that the slip angle α is equal to or smaller than the predetermined slip angle, the condition of the slip angle α is changed (α → α + Δα) (step S414). Then, initial values of the longitudinal force F _x , lateral force F _y , and torque M _{z at} the changed slip angle α are set (step S402), and the longitudinal force F _x ′, lateral force F _y ′, and torque M _z ′ are It is calculated (step S404), a composite square residual sum is calculated (step S406), and the convergence of this composite square residual sum is determined (step S408).
Thus, the slip angle α is repeatedly changed until the predetermined slip angle is reached (step S416). The longitudinal force F _x ′, lateral force F _y ′ and torque M _z ′ are calculated every time the slip angle is changed, and the convergent longitudinal force F _x ′, lateral force F _y ′ and torque M _z ′ are determined. Data of the determined longitudinal force F _x ′, lateral force F _y ′ and torque M _z ′ is stored in the memory 4. Alternatively, these data are output to the output device 7.

  In this way, the characteristic curves of the longitudinal force, lateral force and torque depending on the slip angle α are obtained. In the above example, the slip angle α is changed under the condition that the slip ratio S in the braking / driving direction is a constant value. Thereafter, the slip ratio S in the braking / driving direction is changed to change the longitudinal force, lateral force, A characteristic curve depending on the slip angle α of force and torque can also be obtained. In addition, the slip ratio S in the braking / driving direction can be changed under the condition that the slip angle α is a constant value. In this case, the slip ratio S is repeatedly changed until the slip ratio S in the braking / driving direction reaches a predetermined value.

Using such an apparatus 1, tires are designed according to the flow shown in FIG.
First, in the setting program 9, vehicle specification data and tire design values (dynamic element parameter values) are set (steps S600 and S602). These settings may be set by calling predetermined data from the memory 4, or may be input by an input operation system 5.
Next, the vehicle travel simulation program 10 generates a vehicle model based on the set vehicle specification data. For example, a vehicle model based on a mechanism analysis model is generated (step S604). Further, a traveling simulation condition is set (step S606). Different driving simulation conditions are set according to the performance to be evaluated. For example, when the performance evaluation is durability evaluation, profile data such as the vehicle traveling speed and road surface roughness is set as the traveling condition. In the case of the emergency avoidance performance evaluation, data such as vehicle traveling speed and steering angle, actual road surface profile data, and the like are set as traveling conditions.
On the other hand, based on the dynamic element parameters set in step S600, the F _x / F _y / M _z data calculation program 26 calculates the characteristic curves of the longitudinal force, the lateral force, and the torque that are the dynamic characteristics of the tire. (Step S608).

Next, using the calculated characteristic curve, the “Magic Formula” data parameter calculation program 11 calculates the value of the “Magic Formula” parameter (step S610). Since the dynamic element parameters are set under a plurality of load conditions and a plurality of slip ratio conditions in the braking / driving direction, the characteristic curve is calculated for each condition. For this reason, the value of the “Magic Formula” parameter is also calculated for each condition. Such parameter values are used in the vehicle travel simulation together with the travel simulation conditions.
Next, under the traveling simulation conditions, the vehicle traveling simulation is performed using the vehicle model created in step S604 while calculating the longitudinal force, lateral force and torque from the set “Magic Formula” parameter values. This is performed (step S612).
The running simulation result is stored in the memory 4.

Next, in the integration / management program 13, the driving simulation result is called from the memory 4, the performance evaluation data of the set performance index is calculated (step S614), and the performance evaluation data is set to a preset target value. It is determined whether or not it is satisfied (step S616). If the performance evaluation data does not satisfy the target value, the value of the “Magic Formula” parameter is corrected (step S618). The corrected value is stored in the memory 4.
Note that the performance evaluation data is, for example, the maximum value of stress applied to a specific member or the deformation amount of the specific member in the case of durability performance. In the case of emergency avoidance performance, it is data on the relationship between the traveling speed including braking / driving of the vehicle and the maximum lateral acceleration.
The method of correcting the “Magic Formula” parameter value is not particularly limited, and for example, the parameter value is sequentially changed within a predetermined width.

Next, a dynamic element parameter in the tire dynamic model is derived using the value of the parameter to which this correction has been applied (step S620). Specifically, the “Magic Formula” data parameter calculation program 11 calculates the characteristic curves of the longitudinal force, the lateral force, and the torque, and stores these characteristic curves in the memory 4. Since the value of the “Magic Formula” parameter is set for each of a plurality of load conditions and a plurality of slip ratio conditions in the braking / driving directions, for example, a slip angle-dependent characteristic curve is generated for each condition. . Next, the mechanical element parameters in the tire dynamic model are extracted by the small slip angle condition parameter calculation program 20, and the remaining dynamic elements in the tire dynamic model are further calculated by the F _x / F _y / M _z parameter calculation program 22. A parameter is derived (step S620). The derived dynamic element parameter value is stored in the memory 4 as a dynamic element parameter value corresponding to the “Magic Formula” parameter after modification.

After derivation of the value of the dynamic element parameter, the determination about the achievement of the target is repeatedly performed through steps S606, S612, S614, and S616.
Thus, the dynamic element parameters are repeatedly corrected until the performance evaluation data achieves the target value.
If the result in step S616 is affirmative, the value of the dynamic element parameter stored in the memory 4 is determined as the tire design specification (step S622).
For the value of the dynamic element parameter determined as the tire design specification, a combination of the material of the actual tire member and the tire structure that realizes this value is set. For example, when the determined lateral bending coefficient ε of the belt member is realized by an actual tire, a value of the lateral bending rigidity EI _z (rigidity against the lateral bending of the belt) determined from the lateral bending coefficient ε is realized. As described above, the belt width, belt cord angle, cord material, cord diameter, cord density, and the like are determined. At this time, there are many design factors such as the belt width, belt cord angle, cord material, cord diameter, cord density, etc., which determine the value of the lateral bending rigidity EI _z . Design factors such as belt width, belt cord angle, cord material, cord diameter, cord density and the like are determined in consideration of riding comfort. Such tire design elements include not only the tire structure but also the material type of the tire member. Of these combinations, the tire mechanical element parameter value is maintained while maintaining the durability and riding comfort of the tire. The optimum design element that realizes is determined.

In this way, the tire design specification is expressed by dynamic element parameters that are easy to understand for the tire designer, which constitutes the tire dynamic model reproduced based on the structural mechanics of the tire. It is easy to see if it should be corrected, and it can be easily corrected. In addition, the value of the mechanical parameter in the tire dynamic model can be determined as the tire design specification and can be matched with the value of the “Magic Formula” parameter familiar to vehicle designers. It becomes possible, and development efficiency improves dramatically.
Further, since the mechanical element parameter can be realized by a tire dynamic model, it can be said that the tire design specification can be realized by structural design and material design of the tire. Therefore, a realizable tire design specification can be determined according to the vehicle specification data.

As described above, the apparatus 1 uses the characteristic curves shown in FIGS. 14A and 15B to connect the value of the “Magic Formula” parameter and the value of the dynamic element parameter of the tire.
FIG. 14A shows characteristic curves of the longitudinal force F _x , lateral force F _y , and torque M _z when the load load and the slip ratio S in the braking / driving direction are fixed and the slip angle α is changed. Indicates. FIG. 15B shows characteristic curves of the longitudinal force F _x , the lateral force F _y , and the torque M _z when the load load and the slip angle α are fixed to a constant value and the slip ratio S in the braking / driving direction is changed. Indicates. In these figures, however, the initial torque Mz when applying a positive slip angle α with a slip ratio S = 0 in accordance with the definition of “Magic Formula” and “negative slip ratio and longitudinal force on the braking side” is shown. Negative.

Note that the values of the mechanical element parameters of the tires A and B in FIGS. 14A and 15B are as shown in Table 1 below. The tire traveling speed is 60 km / hour and the load is 4 kmN.
Table 1

Table 2 below shows an example of parameter values of “Magic Formula” obtained from the characteristic curves shown in FIGS. 14 (a) and 15 (b). The parameter values of “Magic Formula” are different values for the tires A and B reflecting the values of the tire dynamic element parameters.
Table 2

FIGS. 16A and 16B are graphs showing load dependency and slip angle dependency graphs for the lateral force F _y , the longitudinal force F _x , and the torque M _z calculated in the device 1.
The values of the dynamic element parameters of the tire are n = 4, C _q = 0.04 (1 / kN), C _xc = (1 / kN), l = 0.117 (m) (load load F _z = 4 kN) , K _x = K _y = 109.7 (kN), A _y = 2.08 (kN · m), ε = 0.06 (1 / (kN · m)), G _mz = 12.0 (kN · m) m / rad), μ _s = 1.8, μ _d = 1.1, and b _v = 0.008.

FIG. 16 (a) shows that the slip angle α is fixed at 1 degree, the slip ratio S in the braking / driving direction is changed within the braking and driving ranges, and the longitudinal force F _x , lateral force F _y and torque M at that time are changed. _It shows the tire friction ellipse in which the calculated value of _z is plotted for each load (2 kN, 4 kN, 6 kN). The upper graph of FIG. 16 (a), the horizontal axis _F x / _{F z} normalized longitudinal force _{F x} in the applied load _{F z,} the lateral force _{F y} applied load _{F z} in normalized _F y / _Fz is plotted along the vertical axis. The lower graph of FIG. 16 (a), the horizontal axis _F x / _{F z} normalized longitudinal force _{F x} in the applied load _{F z, M} z / F normalized torque _{M z} in the applied load _{F z z} is on the vertical axis.

On the other hand, FIG. 16 (b), by fixing the applied load F _z in 4 (kN), braking the slip ratio S of the braking-driving direction, the longitudinal force F _x at that time is varied in a range of driving, the lateral force 3 shows tire friction ellipses in which calculated values of F _y and torque M _z are plotted for each slip angle α (1, 2, 4 and 6 degrees). The upper and lower graphs in FIG. 16B have the same vertical and horizontal axes as the upper and lower graphs in FIG.

FIG. 17 shows a friction ellipse plotted with the longitudinal force F _{x on} the horizontal axis and the lateral force F _y on the vertical axis based on the actual measurement results of the tire at 315 / 80R22.5, high load load 11 kN, and camber angle 0 degree. Some of them are shown. In this friction ellipse, as shown in the figure, the friction ellipse has a negative gradient inclined rightward. Such a gradient is generated by adjusting the value of the movement coefficient C _xc of the contact surface (C _xc = 0% → 50% → 100%) as shown in FIG. Depending on, a negative slope is shown. In addition, the example shown in FIG.20 (d) differs in a tire size and a load load. Also in FIG. 16 (a), the exhibit a negative slope at high applied load _F Z = 6 kN, when the transfer coefficient is a dynamic element parameters in this case _C xc (= 0.04) is set to 0, 16 18 (a) and 18 (b) showing friction ellipses corresponding to (a) and (b), no negative gradient is seen.

As a result, the center position of the ground contact surface of the tire, which has not been considered in the past, is adjusted by using the movement coefficient C _xc that changes according to the longitudinal force F _x , thereby adjusting the negative gradient generated in the actual tire. It becomes possible to represent.

FIGS. 19A, 19B, 20C, and 20D show examples of changes in the tire friction ellipse when the values of the tire dynamic element parameters are changed. FIG. 19A shows the tire friction ellipse when K _x = K _y is changed to 75% and 125% of the current set value (100%), respectively. FIG. 19B shows the tire friction ellipse when the lateral bending stiffness EI _z of the belt is changed to 75% and 125% of the current set value (100%), respectively. FIG. 20 (c) 75% of the current set value sidewall stiffness _{k y} of the tire (100%), shows a tire friction ellipse when changing respectively to 125%.

Note that the lateral bending stiffness EI _z in FIG. 19B has the following relationship with the nonlinear parameter ε.
ε ∝ (EI _z ) ^(−3/2)
Also, the sidewall stiffness _{k y} in FIG. 20 (c) non-linear parameter _epsilon, those having the following relationship with _{G mz.}
ε Α k _y ^(-1/4)
G _mz ｋ k _y
FIG. 20 (d) shows 50% and 0% of the current set value (100%) in which the movement coefficient C _xc that changes according to the longitudinal force F _x is set to a predetermined value for the center position of the tire contact surface. The tire friction ellipse when changed to is shown. Accordingly, by increasing the movement coefficient C _xc , the value on the driving side of the friction ellipse having a line symmetry with the longitudinal force Fx = 0 as the center increases, and the value on the braking side decreases, which makes the friction ellipse negative. It can be seen that the slope of
Thus, it can be seen that the friction ellipse changes by changing the value of the tire dynamic element parameter. Such tire friction ellipse information can be reflected in the value of the “Magic Formula” parameter via the characteristic curve, and can be used effectively for vehicle development.

From the above, the approximate expression parameters in the nonlinear approximate expression that can be expressed as the dynamic characteristics of the tire under braking / driving conditions are connected to the tire dynamic element parameters including various tire stiffnesses through the characteristic curve, and the actual tire The value can be determined as a feasible parameter. Further, since the value of the tire dynamic element parameter is derived every time the value of the approximate expression parameter is corrected, when the vehicle model satisfies a predetermined performance, the value of the tire dynamic element parameter that is easily understood by the tire manufacturer is also determined. . For this reason, the approximate expression parameters in the nonlinear approximate expression expressed as the dynamic characteristics of the tire are linked to the tire dynamic element parameters including various tire stiffnesses, and parameters that can be realized in an actual tire without being a skilled designer. Can be used to efficiently determine the tire design specifications.
The tire dynamic element parameters are parameters that are easily understood by the tire manufacturer, and since it is relatively known what tire dimensions and shapes should be used to adjust the tire dynamic element parameters, A trader can easily design a tire based on the determined tire design specification.

  As described above, the tire design method considering the tire friction ellipse of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention. Of course.

It is a block diagram of the apparatus of one Example which implements the tire design method in consideration of the tire friction ellipse of this invention. It is a figure explaining the tire dynamic model used in the tire design method in consideration of the tire friction ellipse of the present invention. It is another figure explaining the tire dynamic model used in the tire design method in consideration of the tire friction ellipse of the present invention. It is another figure explaining the tire dynamic model used in the tire design method in consideration of the tire friction ellipse of the present invention. (A)-(e) is another figure explaining the tire dynamic model used in the tire design method in consideration of the tire friction ellipse of the present invention. (A)-(d) is another figure explaining the tire dynamic model used in the tire design method in consideration of the tire friction ellipse of the present invention. (A)-(c) is another figure explaining the tire dynamic model used in the tire design method in consideration of the tire friction ellipse of the present invention. It is a processing block diagram until it calculates a lateral force and torque in a tire dynamic model used in a tire design method in consideration of a tire friction ellipse of the present invention. It is a flowchart which shows the flow of one process implemented in the tire design method in consideration of the tire friction ellipse of this invention. It is a flowchart which shows the flow of the other process implemented in the tire design method in consideration of the tire friction ellipse of this invention. It is a flowchart which shows the flow of one process implemented in the tire design method in consideration of the tire friction ellipse of this invention. It is a flowchart which shows the flow of the other process implemented in the tire design method in consideration of the tire friction ellipse of this invention. It is a flowchart which shows the flow of an example of the design method of the tire which considered the tire friction ellipse of this invention. (A) is a figure which shows the example of the characteristic curve used with the design method of the tire which considered the tire friction ellipse of this invention. (B) is a figure which shows the example of the characteristic curve used with the design method of the tire which considered the tire friction ellipse of this invention. (A), (b) is a figure which shows an example of the result of the tire friction ellipse obtained by the design method of the tire which considered the tire friction ellipse of this invention. It is a figure which shows an example of the result of the example of the tire friction ellipse obtained using the conventional tire dynamic element model. (A), (b) is a figure which shows an example of the result of the tire friction ellipse obtained by the design method of the tire which considered the tire friction ellipse of this invention. (A), (b) is a figure which shows an example of the result of the tire friction ellipse obtained by the design method of the tire which considered the tire friction ellipse of this invention. (C), (d) is a figure which shows the other example of the result of the tire friction ellipse obtained by the tire design method in consideration of the tire friction ellipse of this invention.

Explanation of symbols

1 Device 2 CPU
3 Bus 4 Memory 5 Input operation system 6 Interface 7 Output device 8 Program group 9 Setting program 10 Vehicle running simulation program 11 “Magic Formula” data / parameter calculation program 12 Tire dynamic model program group 13 Integration / management program 14 Tire dynamic model calculation Program 20 Small slip angle condition parameter calculation program 22 F _x / F _y / M _z parameter calculation program 24 Small slip angle condition F _x / F _y / M _z data calculation program 26 F _x / F _y / M _z data calculation program

Claims (8)

Of the tire axial force and torque acting on the tire rotation shaft when a slip ratio is given to the tire, information on the characteristic curve representing the slip ratio dependence of at least one of the tire axial force and torque and information on the vehicle specifications are used. A tire design method that takes into account a tire friction ellipse to design a tire that achieves a desired performance by performing a running simulation,
A model creation step for creating a vehicle model using information on vehicle specifications;
Based on a tire dynamic model configured using a plurality of tire dynamic element parameters, the value of the tire dynamic element parameter that defines the characteristic curve is set, and the characteristic curve calculated by the tire dynamic element parameter is a nonlinear approximation formula The approximate equation parameter value that defines the nonlinear approximate equation when approximated by is given to the vehicle model, a travel simulation is performed under a predetermined travel condition, and the performance of the vehicle is evaluated using the result of the travel simulation A performance evaluation step;
In the performance evaluation, when the vehicle model does not satisfy the target performance, the value of the approximate expression parameter is corrected, the corrected value is given to the vehicle model, a driving simulation is performed, and the result of the driving simulation is used. Vehicle performance evaluation, and using a characteristic curve calculated from a nonlinear approximation formula defined by the corrected approximate formula parameter value, the tire dynamic element parameter value is calculated based on the tire dynamic model. A tire characteristic correction step to be derived;
A tire characteristic determination step for determining a value of the derived tire dynamic element parameter as a tire target characteristic when the vehicle model satisfies a predetermined performance;
The tire dynamic model has a longitudinal force generated so that the position of the ground contact surface with respect to the road surface of the tire moves in the front-rear direction due to the longitudinal force generated as the tire axial force when a slip ratio in the braking / driving direction is given. A tire design method that takes into account a tire friction ellipse, characterized in that the center position of the contact surface moves accordingly.   The tire dynamic model calculates a lateral force when a slip angle is given to the tire, a self-aligning torque, a lateral force torque component generated by a lateral force acting on the tire contact surface, and a tire contact surface. The tire design method considering a tire friction ellipse according to claim 1, wherein the model is a model for calculating a self-aligning torque separately for a longitudinal force torque component generated by a longitudinal force acting on the tire. The tire axial force includes at least a lateral force acting in a direction parallel to the tire rotation axis when a slip ratio is given to the tire.
When calculating the characteristic curve using the tire dynamic model, in addition to the lateral force characteristic curve, the slip rate dependence of self-aligning torque generated by lateral force and longitudinal force acting on the road surface The tire design method taking into account the tire friction ellipse according to claim 1 or 2, wherein the characteristic curve is calculated.   When deriving the value of the tire dynamic element parameter in the tire characteristic correction step, the sum of square residuals of the characteristic curve of the longitudinal force and the corresponding curve of the longitudinal force calculated by the tire dynamic model, and the lateral force Corresponding to the square residual sum of the characteristic curve of the tire and the corresponding curve of the lateral force calculated by the tire dynamic model, and the characteristic curve of the self-aligning torque and the self-aligning torque calculated by the tire dynamic model The sum of squared residuals with a curve is a value obtained by weighted addition using a weighting coefficient, and the slip ratio of each characteristic curve of the longitudinal force, the lateral force, and the self-aligning torque is used as the weighting coefficient. The tire so that the value of the composite square residual sum using the coefficient obtained from the information of the variation in the value that varies depending on the value is equal to or less than a predetermined value. Tire design method in consideration of the tire friction ellipse of claim 3 to derive the value of academic element parameters.   In the tire characteristic correction step, when deriving the value of the tire dynamic element parameter from the characteristic curve based on the tire dynamic model, it is given by the torsional deformation of the tire generated by self-aligning torque. The tire design method considering a tire friction ellipse according to any one of claims 1 to 4, wherein a value of a tire dynamic element parameter is derived using an effective slip angle in which the slip angle is corrected.   The value of the tire dynamic element parameter derived in the tire characteristic correction step includes an adhesion friction coefficient between a tire tread member and a road surface, a sliding friction coefficient, and a shape defining coefficient that defines a shape of a contact pressure distribution. Item 6. A tire design method considering the tire friction ellipse according to any one of Items 1-5. When the slip ratio and the slip ratio in the braking / driving direction are given as the slip ratio,
In the tire dynamic model, when calculating the longitudinal force, lateral force and self-aligning torque, the slip direction of the tire in the slip region in the contact surface is determined by a given slip angle and a slip ratio in the braking / driving direction. The method for designing a tire in consideration of a tire friction ellipse according to any one of claims 1 to 6, wherein a longitudinal force, a lateral force, and a cell aligning torque are calculated using the slip direction.   8. The tire design is performed by using a value of the tire dynamic element parameter determined in the tire characteristic determination step to determine a combination of a material and a tire structure of a tire member that realizes the value. The tire design method considering the tire friction ellipse described in the item.

Images