JP5560677B2 - Tire lateral force calculation method and apparatus, tire stiffness parameter value extraction method and apparatus, tire characteristic calculation method and apparatus, tire design method, vehicle motion analysis method, and program - Google Patents

Description

  The present invention relates to a calculation method and apparatus for calculating a lateral force acting on a tire when a camber angle is imparted to a tire that rolls on the ground, and a camber angle that is imparted to a tire that rolls on the ground. Method and apparatus for extracting camber stiffness parameter value used for calculating lateral force in tire dynamic model for calculating lateral force acting on tire, tire characteristic calculating method and apparatus using these methods, and tire design The present invention relates to a method, a vehicle motion analysis method, and a computer-executable program.

Today, various methods have been proposed for predicting tire cornering characteristics and braking / driving characteristics using tire dynamic models.
Specifically, the cornering characteristics and braking / driving characteristics of a tire are tire characteristic curves represented by a graph in which the horizontal axis represents a slip angle and the vertical axis represents lateral force or braking / driving force. This characteristic curve data is incorporated into a separately created vehicle model and used for motion performance simulation using the vehicle model. Therefore, it is desired to accurately predict and calculate the cornering characteristics and braking / driving characteristics of a tire so that a motion performance simulation can be accurately performed and a correct evaluation can be performed.

  The tire dynamic model is an analysis model configured using a plurality of tire dynamic element parameters. The tire dynamic element parameters include the lateral stiffness determined by the lateral shear stiffness of the tire tread portion and the shear stiffness in the front-rear direction (braking / driving direction) of the tire tread portion, the coefficient of static friction between the road surface and the tire, the road surface In addition to the coefficient of dynamic friction between tires, various coefficients are included. Thus, since the tire dynamic element parameters in the tire dynamic model are defined with the same degree of fineness as the tire constituent members such as the tire tread portion and the belt portion, the values of the tire dynamic element parameters and the types of the tire constituent members are defined. There is a strong correspondence between Therefore, if the preferable direction of the value of the tire dynamic element parameter is determined from the result of the above-described motion performance simulation, the type of the tire constituent member may be changed according to this direction.

A tire design method using such a tire dynamic model is described in Patent Document 1 below.
However, in Patent Document 1, since the ground camber angle when the tire is mounted on the vehicle is 0 degree, the cornering characteristics and braking / driving characteristics calculated in Patent Document 1 are vehicle-mounted tires with ground camber angles. There is a problem that the cornering characteristics and braking / driving characteristics are not necessarily reproduced accurately.

On the other hand, Non-Patent Document 1 below shows a tire model having a camber angle. The right column on the third page of the document describes formulas for calculating canvas last (lateral force) (formulas (12) and (13)). According to the equation (12) of this document, the canvas last (lateral force) is calculated by multiplying the lateral stiffness _{Cy y} by the bending deformation of the belt. Therefore, the calculated canvas last (lateral force) increases linearly in proportion to the increase in camber angle. However, the camber angle dependence of the canvas last (lateral force) actually measured is indicated by a curve, not a straight line. In the canvas last of Fig. 12 shown on page 4 of this document, it can be seen that the measured value changes nonlinearly with the camber angle. Thus, it can be said that the camber angle dependence of canvas last (lateral force) in the document is not accurately expressed.

JP 2008-49725 A

“Modeling of tires with camber angle”, Ichiro Kageyama, Satoru Kuwahara, Proceedings of the 9th Annual Meeting of the Japan Society of Mechanical Engineers Transport and Logistics [2000-12.13-15, Kawasaki], pp. 27-30

  Therefore, in order to solve the conventional problems, the present invention provides a method and apparatus capable of accurately calculating the lateral force acting on the tire when the camber angle is given, and this method and apparatus Method and apparatus for extracting camber stiffness parameter value of tire dynamic model, method and apparatus for accurately calculating tire characteristic of tire with camber angle, tire design method, vehicle motion analysis method, and An object of the present invention is to provide a program for implementing these methods.

One aspect of the present invention is a calculation method for calculating a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground,
Setting a camber stiffness parameter value used in a tire dynamic model capable of calculating a lateral force;
Calculating a lateral force in accordance with the tire dynamic model using the set value of the camber stiffness parameter and a given camber angle. At that time, when calculating the lateral force, the tire dynamic model uses a corrected camber angle in which the assigned camber angle is corrected according to the lateral force.

Another aspect of the present invention is a tire dynamic model for calculating a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground, and a camber stiffness used for calculating the lateral force. A method for extracting parameter values,
Obtaining experimental data representing a relationship between a given camber angle and a lateral force generated by the camber angle;
Extracting a value of a camber stiffness parameter used in a tire dynamic model capable of calculating a lateral force using the experimental data;
Outputting the value of the extracted camber stiffness parameter. At that time, the tire dynamic model uses a corrected camber angle in which the assigned camber angle is corrected according to the lateral force.

Yet another aspect of the present invention is a computer-executable program for causing a computer to calculate a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground,
A procedure for causing the computer to set the value of the camber stiffness parameter used in the tire dynamic model capable of calculating the lateral force;
Using the value of the set camber stiffness parameter and the assigned camber angle to cause the computer to calculate and output a lateral force according to the tire dynamic model. At that time, when the lateral force is calculated using the tire dynamic model, a corrected camber angle obtained by correcting the applied camber angle according to the lateral force is used.

Yet another aspect of the present invention is a calculation device for calculating a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground,
A setting unit for setting a value of a camber stiffness parameter used in a tire dynamic model capable of calculating a lateral force;
A calculation unit that calculates a lateral force according to the tire dynamic model using the value of the set camber stiffness parameter and a given camber angle. At this time, when calculating the lateral force, the calculation unit uses a corrected camber angle in which the assigned camber angle is corrected according to the lateral force.

Still another aspect of the present invention is a tire dynamic model for calculating a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground, and the camber used for calculating the lateral force. A computer-executable program that causes a computer to extract the value of a stiffness parameter,
A procedure for causing a computer to acquire experimental data representing a relationship between a given camber angle and a lateral force generated by the camber angle;
A procedure for causing the computer to extract the value of the camber stiffness parameter used in the tire dynamic model capable of calculating the lateral force, using the experimental data;
And a procedure for outputting the extracted camber stiffness parameter value. At that time, the tire dynamic model uses a corrected camber angle in which the assigned camber angle is corrected according to the lateral force.

Yet another aspect of the present invention is used when calculating the lateral force in a tire dynamic model for calculating a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground. A device for extracting the value of a camber stiffness parameter,
A data acquisition unit that acquires experimental data representing the relationship between the assigned camber angle and the lateral force generated by the camber angle;
An extraction unit for extracting the value of the camber stiffness parameter used by the tire dynamic model capable of calculating the lateral force using the experimental data;
And an output unit that outputs the value of the extracted camber stiffness parameter. At that time, the tire dynamic model uses a corrected camber angle in which the assigned camber angle is corrected according to the lateral force.

Still another aspect of the present invention is a tire characteristic calculation for calculating a cornering characteristic and / or a braking / driving characteristic of a tire under a condition where a camber angle is given based on a tire dynamic model using a plurality of tire dynamic element parameters. A method,
Setting a value of a tire dynamic element parameter used in the tire dynamic model;
Calculating cornering characteristics and / or braking / driving characteristics in accordance with the tire dynamic model using the set values of the tire dynamic element parameters. In this case, the tire dynamic element parameter includes a tire stiffness parameter extracted by the tire stiffness parameter value extraction method.

Yet another aspect of the present invention is an evaluation step for evaluating cornering characteristics and / or braking / driving characteristics calculated by the tire characteristic calculation method,
And a design step of changing a tire shape or a tire constituent member that realizes the value of the tire dynamic element parameter in accordance with the evaluation result.

Still another aspect of the present invention is a step of obtaining cornering characteristics and / or braking / driving characteristics calculated by the tire characteristic calculation method;
Applying a cornering characteristic and / or a braking / driving characteristic to a vehicle model that reproduces the vehicle, and analyzing a vehicle movement characteristic.

Since the tire dynamic model used in the tire lateral force calculation method and device and the tire stiffness parameter value extraction method and device described above uses a modified camber angle, the tire characteristics of the tire to which the camber angle is given can be accurately calculated. In addition, the tire stiffness parameter value can be calculated accurately.
Therefore, using this tire dynamic model, the tire characteristic calculation method and apparatus, and the program can accurately calculate the tire characteristics such as the cornering characteristic or the braking / driving characteristic of the tire to which the camber angle is given. Therefore, the calculated tire characteristics can be effectively applied to a tire design method and a vehicle motion analysis method.

It is a figure explaining the force, moment, and direction which act on a tire. It is a figure which shows the structure of the apparatus of this embodiment. (A), (b) is a figure explaining the tire dynamic model used for the method of this embodiment. It is a figure explaining the partial model 1 of the tire dynamic model shown to Fig.3 (a), (b). (A), (b) is a figure explaining the change of the contact shape used with the partial model 1 shown in FIG. It is a figure explaining generation | occurrence | production of the canvas last used with the partial model 1 shown in FIG. (A), (b) is a figure explaining the correction camber angle used with the partial model 1 shown in FIG. It is a figure explaining the flow which extracts the value of the tire dynamic element parameter performed in the parameter extraction part and tire dynamic model calculation part shown in FIG. It is a figure explaining the flow which calculates the canvas last performed in the tire characteristic calculation part and tire dynamic model calculation part which are shown in FIG. It is a figure which shows an example of the calculation result of the tire characteristic showing the camber angle dependence of the canvas last calculated by the flow shown in FIG. It is a figure explaining the partial model 2 of the tire dynamic model shown to Fig.3 (a), (b). It is a figure explaining the partial model 3 of the tire dynamic model shown to Fig.3 (a), (b). (A)-(e) is a figure explaining the mechanism used by the partial models 2 and 3 shown in FIG. 11, FIG. (A)-(d) is a figure explaining the other mechanism used with the partial models 2 and 3 shown to FIG. 11, FIG. (A)-(c) is a figure explaining the other mechanism used by the partial models 2 and 3 shown in FIG. 11, FIG. It is a figure explaining the calculation process of the longitudinal force, lateral force, and self-aligning torque which are calculated by the partial models 2 and 3 shown in FIGS. It is a figure explaining the flow which calculates a tire characteristic using the partial models 2 and 3 shown by FIG. 11, FIG. (A), (b) is a figure which shows an example (camber angle (gamma) = 0) of the calculation result of a tire characteristic. (A), (b) is a figure which shows an example (camber angle (gamma) = + 4 degree | times) of the calculation result of a tire characteristic. (A), (b) is a figure which shows an example (camber angle (gamma) =-4 degree) of the calculation result of a tire characteristic. (A)-(c) is a figure which shows the other example of the calculation result of a tire characteristic.

  Hereinafter, a tire lateral force calculation method and apparatus, a tire stiffness parameter value extraction method and apparatus, a tire characteristic calculation method and apparatus, a tire design method, a vehicle motion analysis method, and a program according to the present invention will be described in detail. .

FIG. 1 is a diagram illustrating a force and a torque (moment) acting on a tire.
Lateral force F _y described later, among the forces which the tire receives from the road surface, means a direction component of the tire rotation axis, the longitudinal force F _x, of the forces which the tire receives from a road surface, the direction of the tire-wheel center plane Refers to the ingredients. The slip angle α is an angle at which the traveling direction of the tire deviates from the tire wheel center plane. The self-aligning torque M _z is a torque acting around an axis that passes through the center of contact of the tire and is perpendicular to the road surface. The self-aligning torque M _z is a torque for rotating the tire so as to increase or decrease the slip angle. The camber angle γ is an angle at which the tire wheel center plane is inclined with respect to a direction perpendicular to the ground.
The overturning moment M _x refers to a torque that acts in a direction to increase or decrease the camber angle γ.
Both the force and torque can be measured with an actual tire as physical quantities acting on the tire shaft.

(Outline of the apparatus of this embodiment)
FIG. 2 is a diagram illustrating a configuration of the apparatus 1 that performs a tire lateral force calculation method, a tire stiffness parameter value extraction method, a tire design method, a vehicle motion analysis method, and a tire characteristic calculation method.

  The device 1 is configured by a computer that executes various programs, calculates a lateral force (canvas last) of a tire, extracts a value of a tire stiffness parameter, calculates a tire characteristic, and performs vehicle motion analysis. Or, suggesting the design of the tire, such as changing the type of the tire component.

The device 1 calculates tire characteristics by calculating the lateral force of the tire with respect to the camber angle γ, and uses the tire characteristics to perform a vehicle running simulation and analyze the motion of the vehicle. The device 1 further suggests a change in the tire shape or the tire constituent member by knowing the preferable direction of the tire as seen from the vehicle running simulation and determining the value of the tire stiffness parameter that matches this direction. Furthermore, the apparatus 1 extracts the value of the tire stiffness parameter that determines the canvas last (lateral force F _y ) generated by applying the camber angle γ.

  As shown in FIG. 2, the apparatus 1 indicates a CPU 2 that manages and controls execution of each part of the computer and a program, a memory 4 that stores various conditions and calculation results via a bus 3, and indicates various conditions and various information. Input operation system 5 such as mouse and keyboard to be input, interface 6 that connects the input operation system 5 to the bus 3, various conditions and information input screens, and processing results of various programs including simulation results are displayed on the screen. And an output device 7 for printing out, and a module group 8 generated by executing various programs.

Here, the module group 8 includes a setting unit 9, a tire characteristic calculation unit 10, a parameter extraction unit 11, a tire dynamic model calculation unit 12, a vehicle travel simulation unit 13, and an integration / management unit 14.
The setting unit 9 sets values of various tire dynamic element parameters of a tire dynamic model described later. This set value is used for calculation of lateral force, longitudinal force, and self-aligning torque in the tire dynamic model calculation unit 12. Furthermore, the setting part 9 sets each value of the vehicle specification used for a vehicle running simulation. The set value is used for simulation in the vehicle travel simulation unit 13. These settings are made based on input by the operator using the input operation system 5.
The memory 4 stores the value of the tire dynamic element parameter of the tire currently under consideration and each value of the vehicle terms under consideration as a set, and the setting unit 9 calls the value of this set to set the value. Settings can also be made.
The setting unit 9 sets a tire load, a slip angle to be calculated, a slip ratio indicating braking / driving, a camber angle, or a range thereof. The set load load, slip angle, slip ratio, camber angle, or a range thereof is sent to the tire characteristic calculation unit 10 and parameter extraction unit 11, tire dynamic model calculation unit 12, and vehicle travel simulation unit 13. The setting unit 9 also sets processing details such as whether to calculate tire characteristics, to extract values of tire dynamic element parameters, or to perform a vehicle running simulation.

  The tire characteristic calculation unit 10 calculates a lateral force, a longitudinal force, or a self-aligning torque based on the set slip angle, slip ratio, and camber angle in accordance with an instruction from the integration / management unit 14. When the range of the slip angle, the slip ratio, or the camber angle is set, the tire characteristic calculation unit 10 sequentially determines the values of the slip angle, the slip ratio, and the camber angle with a predetermined step size within the set range, Calculate lateral force, longitudinal force, and self-aligning torque. Specifically, the determined slip angle, slip ratio, and camber angle values are provided from the tire characteristic calculation unit 10 to the tire dynamic model calculation unit 12, and the lateral force calculated by the tire dynamic model calculation unit 12, The force or self-aligning torque is returned to the tire characteristic calculator 10. That is, the part that mainly calculates the lateral force, the longitudinal force, and the self-aligning torque is the tire dynamic model calculation unit 12, and the tire characteristic calculation unit 10 calculates the lateral force and the longitudinal force calculated by the tire dynamic model calculation unit 12. The tire characteristics are obtained smoothly using the self-aligning torque. The calculated tire characteristic calculation results are stored in the memory 4. The calculation result of the tire characteristics is evaluated by the integrated management unit 14 and reflected in the tire design. Alternatively, the calculated calculation result of the tire characteristics is used in the vehicle travel simulation unit 13 and used for the tire travel simulation.

The tire characteristics include, for example, a characteristic curve determined on a graph represented by a slip angle on the horizontal axis and a lateral force or self-aligning torque on the vertical axis. In the case of conditions in which the slip ratio, camber angle, and tire load are varied, the tire characteristics include characteristic curves on the graph for each of these conditions.
Alternatively, the tire characteristics include a characteristic curve determined on a graph represented by a slip ratio on the horizontal axis and a lateral force or self-aligning torque on the vertical axis. In the case of conditions where the slip angle, camber angle and tire load are varied, the tire characteristics include characteristic curves on the graph for each of these conditions.
Alternatively, the tire characteristics include a characteristic curve determined on a graph represented by the longitudinal force on the horizontal axis and the lateral force on the vertical axis. For example, in the case of conditions in which the slip angle, the slip ratio, the camber angle, and the load load on the tire are variously changed, the tire characteristics include a characteristic curve on the graph for each of these conditions.
Alternatively, the tire characteristics include a characteristic curve determined on a graph represented by a camber angle on the horizontal axis and a lateral force or self-aligning torque on the vertical axis. For example, in the case of conditions in which the slip angle, the slip ratio, and the load load on the tire are variously changed, the tire characteristics include a characteristic curve determined by the above graph for each of these conditions.

The parameter extraction unit 11 calls and acquires experimental data representing the relationship between the assigned camber angle γ and the lateral force F _y generated by the camber angle γ from the memory 4 in accordance with an instruction from the integration / management unit 14. Then, using the tire dynamic model calculation unit 12, the value of canvas stiffness (camber stiffness parameter) is extracted from the acquired experimental data. The extraction result is stored in the memory 4. Further, the tire characteristic calculation unit 10 can calculate the tire characteristic using the extraction result.

The tire dynamic model calculation unit 12 gives a value of the tire dynamic element parameter to the tire dynamic model so that it can be calculated. From the tire characteristic calculation unit 10 or the parameter extraction unit 11, the load load, the contact length, the contact width, and the slip angle are obtained. When a value such as a slip ratio or a camber angle is provided, a lateral force F _y , a longitudinal force F _x , or a self-aligning torque M _z is calculated using a tire dynamic model that can be calculated. Is returned to the tire characteristic calculation unit 10 or the parameter extraction unit 11.
The tire dynamic model will be described later.

The vehicle running simulation unit 13 incorporates each value of the vehicle specifications set by the setting unit 9 into the vehicle model so as to enable simulation. Further, the vehicle travel simulation unit 13 uses the tire characteristic data generated by the tire characteristic calculation unit 10 based on an instruction from the integration / management unit 14 and travels the vehicle under the travel conditions set by the setting unit 9. Carry out simulation (vehicle motion analysis). In the running simulation, for example, a running condition including a running speed of the vehicle including braking / driving, a steering angle, or road surface unevenness is used. The calculation result is stored in the memory 4.
Thereafter, the calculation result is called from the integration / management unit 14, used for tire performance evaluation, and reflected in the tire trial manufacture.
As the vehicle model used in the vehicle running simulation, for example, a motion analysis software CarSim, an analysis model defined by the control design software MatLab, a model created by the mechanism analysis software ADAMS, or the like is used.
In addition, when the characteristic curve data representing the tire characteristics is approximated by a non-linear approximation formula defined by parameters and a vehicle running simulation is performed, the running simulation can also be performed using the parameter values of the non-linear approximation formula.
For example, the well-known “Magic Formula” (http://www.tytlabs.co.jp/japanese/review/rev343pdf/343_039mizuno.pdf) can be used as the nonlinear approximation formula.

The integration / management unit 14 instructs processing contents such as calculation of tire characteristics, extraction of values of tire dynamic element parameters, vehicle running simulation, and the like in the module group 8 according to the contents set in the setting unit 9. Further, the integration / management unit 14 performs tire performance evaluation on the tire characteristic data obtained by the tire characteristic calculation unit 10 or based on the calculation result obtained by the vehicle travel simulation unit 13. For example, the integration / management unit 14 corrects the value of the tire dynamic element parameter so that the tire characteristic data or the calculation result of the running simulation approaches the target, and the type of tire constituent member or the tire shape corresponding to the correction. Changes are suggested to the operator through the output device 7. Since the target of the tire characteristic or the calculation result of the running simulation is determined before the development of the tire, the type of the tire constituent member used for the tire under investigation can be easily changed. For example, when the value of the lateral force F _y in the tire characteristics is 5% lower than the target, the integration / management unit 14 suggests that the modulus of the tread rubber member of the tire is increased by 8% through the output device 7. Further, the integration / management unit 14 proposes to the operator the rubber composition of the tread rubber necessary for increasing the modulus by 8% through the output device 7.
The reason why such a tire can be designed is that there is a strong correspondence between the tire dynamic element parameters of the tire dynamic model and the tire constituent members. In this case, in order to efficiently suggest or propose a tire design, it is preferable to provide a table in which the values of the tire dynamic element parameters correspond to the types of the tire constituent members.

(Tire dynamic model)
A tire dynamic model used in the tire dynamic model calculation unit 12 in the apparatus 1 will be described.

The tire dynamic model used in the tire dynamic model calculation unit 12 is a model represented by an analytical expression, and the longitudinal force, lateral force, or self-aligning torque is calculated using the set value of the dynamic element parameter.
The tire dynamic model is used when the tire characteristic calculation unit 10 calculates tire characteristics and the parameter extraction unit 11 extracts tire dynamic element parameter values. In the parameter extraction section 11, the tire dynamic element parameters which value is extracted is a canvas stiffness C _gamma and lateral torsional rigidity G _my.

As shown in FIG. 3 (a), 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 an elastic ring body connected to these spring elements. And a tread model composed of an elastic element connected to the surface of the elastic ring body.
The tire dynamic model is integrated with a plurality of specialized partial models. The tire dynamic model includes a partial model 1 for calculating the canvas last (lateral force) used in the parameter extracting unit 11, and a partial model for calculating the lateral force _Fy , the longitudinal force _Fx, or the self-aligning torque _Mz in the braking state. 2 and a partial model 3 for calculating the lateral force F _y , the longitudinal force F _x, or the self-aligning torque M _z in the driving state. First, in order to facilitate understanding of the tire dynamic model, a description will be given from the partial model 1 for calculating the camber angle γ and the canvas last (lateral force F _y ) generated with the camber angle γ.

(Partial model 1)
FIG. 4 is a diagram for explaining the partial model 1 for calculating the canvas last (lateral force F _y ).
When the camber angle γ is input, the partial model 1 calculates the lateral force F _y that is the canvas last according to the equation (20) or the equation (21) in FIG. At this time, values are set for the lateral torsional stiffness G _my and the canvas stiffness (camber stiffness parameter) C _γ that are the tire dynamic element parameters, and further, values are set for the contact width w, the contact length l, and the distance h. Model 1 is ready for computation.
As shown in FIG. 4, since the equations (20) and (21) are recursive equations with respect to the lateral force F _y , the tire characteristic calculation unit 10 uses the Newton-Raphson method or the like to calculate the lateral force F _y. To decide.

The parameter extraction unit 11 can also extract the values of the lateral torsional rigidity G _my and canvas tiffine C _γ using the partial model 1. The parameter extraction unit 11 searches for the optimum value while changing the values of the lateral torsional rigidity G _my and canvas stiffness C _γ so as to optimally approximate the characteristic curve of the acquired experimental data. Therefore, the parameter extraction unit 11 changes the values of the lateral torsional rigidity G _my and canvas stiffness C _γ sequentially, and the lateral force F _y substantially matches each value of the experimental data within the set range of the camber angle γ. As described above, the values of the lateral torsional rigidity G _my and canvas tiffine C _γ are obtained. At this time, since the lateral force F _y that is the canvas last is calculated using equations (20) and (21) that are recursive equations of the partial model 1, the parameter extraction unit 11 uses the Newton-Raphson method or the like.

5A, 5B to 7A, 7B are diagrams for explaining the mechanism of the partial model 1. FIG. For easy understanding, as shown in FIG. 5 (a), the ground is inclined by the camber angle γ instead of the tire. In this case, the portion where the deflection changes most among the deflection of the tire due to the inclination changes by w · tan γ / 2 with respect to the center portion.
On the other hand, as shown in FIG. 5 (b), when the tire is viewed from the side, the tangential gradient of the ground contact edge of the tire in FIG. 5 (b) is l / (2h). By dividing / 2 by the tangential gradient l / (2h), the minimum contact length l _a (= 1−2 ht wan γ / l) and the maximum contact length l _b (= l + 2 ht γ γ / l) are calculated by the camber angle γ. l is the contact length at the contact center position at the camber angle γ = 0, and h is the distance between the contact center and the tire center. The contact length at the contact center position has a length l that is invariant with respect to the camber angle γ.
Thus, by giving the camber angle γ, as shown in FIG. 5B, the ground contact shape changes from a rectangular shape to a trapezoidal shape. Further, when the camber angle γ increases, the ground contact shape changes to a triangular shape with the minimum ground contact shape l _a = 0. That is, the ground contact shape changes to a triangular shape when | η |, which is an absolute value of η described later, is larger than 1. At this time, the grounding width w is narrowed.

On the other hand, FIG. 6 is a diagram for explaining a generation mechanism of the lateral force F _y that is the canvas last generated when the camber angle is given to the tire in the partial model 1.
As shown in FIG. 6, the state of the tire projected onto a plane parallel to the tire wheel center plane of the tire inclined with the camber angle γ is considered. At this time, the sin γ component of the radial force of the tire caused by the longitudinal deflection of the tire corresponds to the lateral force F _y that is the canvas last.
The longitudinal deflection is represented by l ² / (2r) · x ₁ / l · (1−x ₁ / l) using x ₁ in the figure. Therefore, the vertical deflection is multiplied by the stiffness C _z , and the camber angle γ is corrected to γ + η · F _y / G _my to obtain the trapezoidal ground contact surface shown in FIG. By performing the area integration along the side, the lateral force F _y which is the canvas last can be calculated. A product obtained by multiplying the stiffness C _z by w · l ³ / (12r) corresponds to the canvas stiffness C _γ . That is, C _γ = w · l ³ / (12r) · C _z .

As described above, the camber angle γ is corrected even if the camber angle γ is given as shown in FIG. 7A, according to the lateral force F _y as shown in FIG. This is because the assigned camber angle γ is corrected. Specifically, the camber angle is corrected by the overturning moment M _x generated due to the lateral force F _y . Η in the correction amount of the camber angle γ is a contact length change rate due to the camber angle γ, and the contact length l of the center portion in the contact surface (the contact length l of the center portion is invariable with respect to the camber angle γ). Is _a half value of the ratio of the difference between the maximum contact length l _b and the minimum contact length l _a . That is, η = (l _b −l _a ) / (2l).
The above explanation, a case camber angle γ is positive, in FIG. 5 (a), (b) , if camber angle γ is negative, l _a maximum contact length, l _b is minimized contact length, η also takes a negative value.

Specifically, the overturning moment M _x is increased by the movement of the ground contact surface due to the lateral force F _y , and in order to determine how much the camber angle γ is corrected by this increase, η · F _y is the lateral torsional rigidity. Divide by G _my . Therefore, the correction amount of the camber angle γ by the overturning moment M _x is η · F _y / G _my . The reason why the contact length change rate η is multiplied here is that the change in the shape of the contact surface and the contact pressure influence the overturning moment M _x .
Thus, as shown in the following equation, the lateral force F _y that is the canvas last is calculated by performing area integration of the ground contact surface. Depending on whether | η | is greater than or less than 1, Equation (20) or Equation (21) is selected as shown in FIG. This is because when | η | is greater than 1, the trapezoidal shape changes to a triangular grounding surface, and the area integration value of the grounding surface changes.

Thus, the partial model 1 of the tire dynamic model becomes a recursive equation by correcting the camber angle γ with the correction amount η · F _y / G _my as shown in the equations (20) and (21). For this reason, the canvas last does not change linearly according to the camber angle γ as in the prior art, but changes nonlinearly.

FIG. 8 is a diagram showing a flow for extracting values of the canvas stiffness C _γ and the lateral torsional rigidity G _{my in} the partial model 1.

First, the parameter extraction unit 11 sets the contact width w of the contact surface, the contact length l, and the distance h between the contact center and the tire center under the conditions of the set load load F _z and the camber angle γ = 0 (see FIG. 1). ) Is retrieved from the memory 4 (step S10).

Next, the parameter extraction unit 11 retrieves and acquires experimental data (lateral force F _{y for} each camber angle γ) on the camber angle γ of the lateral force F _y that is the canvas last from the memory 4 (step S20). Furthermore, the parameter extracting unit 11 sets the canvas tiff initial value Ness C _gamma and lateral torsional rigidity G _my (step S30). The initial value setting method is not particularly limited. The value of canvas stiffness C _γ determined in the past and the value of lateral torsional rigidity G _my may be used as initial values.

Parameter extracting unit 11, provides contact width w, and the contact length l, and the distance h, the experimental data, the initial value and the initial value of the lateral torsional rigidity G _my canvas stiffness C _gamma, the tire dynamic model computing section 12 Then, the partial model 1 of the tire dynamic model is put into a state where calculation is possible. Accordingly, the tire dynamic model calculation unit 12 calculates the lateral force F _y ′ for each camber angle γ according to the equations (20) and (21) of the partial model 1 using the lateral force F _y of the experimental data (step) S40). The calculated lateral force F _y ′ for each camber angle γ is provided to the parameter extraction unit 11.
The parameter extraction unit 11 calculates a square residual sum between the calculated lateral force F _y ′ for each camber angle γ and the corresponding lateral force F _y of the experimental data (step S50), and this square residual is calculated. It is determined whether or not the sum is equal to or less than a predetermined value, that is, whether or not the lateral force F _y ′ has converged on the lateral force F _y (step S60).

In the above determination, when the lateral force F _y ′ has not converged (in the case of No), the values of canvas stiffness C _γ and lateral torsional rigidity G _my are adjusted (step S70). The value is adjusted using, for example, the Newton-Raphson method.
In the above determination, when the lateral force F _y ′ converges (in the case of Yes), the parameter extraction unit 11 uses the values of the canvas stiffness C _γ and the lateral torsional rigidity G _{my that} are set to reproduce the tire characteristics. It determines as a value of an element parameter (step S80). The determined value is stored in the memory 4 and output to the output device 7.
Such processing is executed in the apparatus 1 using a program.

FIG. 9 shows a flow of calculating tire characteristics representing the camber angle γ dependence of the lateral force F _{y at} the slip angle α = 0 in the partial model 1 using the values of the canvas stiffness C _γ and the lateral torsional rigidity G _my. FIG.

First, the tire characteristic calculation unit 10 receives the range of the camber angle γ set by the setting unit 9, and further, the contact width w and the contact length l under the condition of the tire load load F _z set by the setting unit 9. And the value of the distance h is retrieved from the memory 4 (step S100). Moreover, the tire characteristic calculation unit 10 obtains from the memory 4 by calling the canvas tiff value Ness C _gamma and lateral torsional rigidity G _my (step S110).
Next, the tire characteristic calculation unit 10, the value of the lateral force F _y is initially set (step S120). The initial setting method is not limited, but the value is set with reference to the lateral force calculated in the past, for example.

Next, the tire characteristic calculation unit 10 provides the set values to the tire dynamic model calculation unit 12 so that the partial model 1 of the tire dynamic model can be calculated. Tire dynamic model computing section 12, wherein the partial model 1 using the lateral force F _y, which is the camber angle γ and setting set (20), calculates the according (21), the lateral force F _y '(step S130 ). The calculated lateral force F _y ′ is provided to the tire characteristic calculation unit 10.
The tire characteristic calculator 10 calculates an error between the lateral force F _y ′ and the lateral force F _y (step S140), and the lateral force F _y converges depending on whether or not the absolute value of this error is equal to or less than a predetermined value. It is determined whether or not (step S150).

Result of the determination, if the lateral force F _y is not converged (in the case of No), the tire characteristic calculating unit 10 adjusts the value of the lateral force F _y (step S160). The method for adjusting the lateral force F _y is not particularly limited, but is performed using, for example, the Newton-Raphson method. If the lateral force F _y is converged, the tire characteristic calculation unit 10, the value of the lateral force F _y is determined as a value representing a tire characteristic (step S170).

Next, the tire characteristic calculation unit 10 determines whether or not to determine the lateral force F _y for all camber angle gamma (step S180). In this determination, when the lateral force F _y is not determined for all the camber angles γ (in the case of No), the camber angle γ is changed by a predetermined step size (step S190), and the process returns to step S120. again, the initial setting of the lateral force F _y.
When the lateral force F _y is determined for all the camber angles γ (in the case of Yes), the tire characteristic calculation unit 10 ends the calculation of the tire characteristics and stores the calculation result in the memory 4. Further, the tire characteristic calculation unit 10 causes the output device 7 to output the calculation result.
Such processing is executed in the apparatus 1 using a program.

FIG. 10 is a diagram showing the camber angle γ dependency of the canvas last of a tire of 215 / 55R17 63V (air pressure 230 kPa, load load 4. rolling speed 5 km / hour).
The “present invention” in the figure extracts the values of the lateral torsional rigidity G _my and canvas stiffness C _γ (= C _z · w · l ³ / (12r)) so as to approximate the obtained experimental data, It is the result of having used the tire characteristic calculation part 10 and calculating the dependence of the camber angle γ of the canvas last.
The conventional example changes linearly with respect to the camber angle γ. On the other hand, the present invention using a tire dynamic model that adopts a modified camber angle in which the camber angle γ is corrected by a correction amount η · F _y / G _my is a calculation result that approximates the experimental data of the actual canvas last. Can be obtained.

(Partial models 2 and 3)
Next, the partial models 2 and 3 will be described.
The partial models 2 and 3 are models that incorporate the above-described partial model 1 and calculate tire characteristics in the braking / driving state of the tire. The partial models 2 and 3 calculate a longitudinal force F _x , a lateral force F _y and a self-aligning torque M _z in a braking state and a driving state in which the force is in a balanced state (equilibrium state) in the tire dynamic model. The partial model 2 is used when the slip ratio is in a braking state, and the partial model 3 is used when the slip ratio is in a driving state.
The tire dynamic model calculation unit 12 calculates the longitudinal force F _x , the lateral force F _y, or the self-aligning torque M _z using the value of the dynamic element parameter. The calculation result is stored in the memory 4 and output to the output device 7.

  In the partial models 2 and 3 to be described later, the grounding shape of the grounding surface becomes a trapezoidal shape or the trapezoidal shape further advances to a triangular shape depending on the magnitude of the camber angle γ. When the absolute value | η | of the contact length change rate is 1 or less, the contact surface has a trapezoidal shape. When | η | is greater than 1, the contact surface has a triangular shape. Since | η | is 1 or less in the range of the practical camber angle γ used in the vehicle, the following description will focus on an example in which | η | is 1 or less as a preferred embodiment. When | η | is larger than 1, Expression (4) described later is represented by the following Expression (4A), Expression (6) is represented by the following Expression (6A), Expression (7) is represented by the following Expression (7A), and Expression (8 ) In the following formula (8A), formula (14) in the following formula (14A), formula (16) in the formula (6A), formula (17) in the following formula (17A) and formula (18) in the following formula. It is changed to Formula (18A).

Examples of the tire dynamic element parameters used in 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) Coefficient of static friction between road surface and tire, μ _s ,
(E) Coefficient of dynamic friction 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) Canvas Tiffness C _γ that produces canvas last,
(I) Lateral torsional rigidity G _{my of} the ground plane
(J) Coefficients n, q ₀ that specify the contact pressure distribution on the contact surface during lateral force generation
(K) a coefficient C _q representing the degree of deflection of the ground pressure distribution,
(L) a movement coefficient C _xc indicating the degree of movement of the center position of the tire contact surface in the front-rear direction
(M) The effective contact length l when the lateral force is generated.

Here, the lateral stiffness K _y , the longitudinal stiffness K _x , and the torsional stiffness A _y are perpendicular to the ground contact surface through the lateral stiffness parameter, the longitudinal stiffness parameter, the tire ground contact center with respect to the shear deformation of the tire tread portion, respectively. This is a stiffness parameter of torsion around a specific axis. Lateral bending coefficient epsilon, G _mz of the torsional compliance (1 / G _mz) is a stiffness parameter with respect to the stiffness parameter and torsional deformation of tires with respect to the lateral bending deformation of the belt member. Canvas stiffness C _gamma, generates a radial force of the tire according to the deflection vertical shown in Figure 6. The lateral torsional rigidity G _my of the contact surface is a rigidity when the tire is twisted by being pulled in the lateral direction on the contact surface.
Note that the lateral direction, which is the direction in which the lateral force is generated, is the axial direction of the tire rotation axis, so the lateral direction when the tire rolls in a straight traveling state is a direction orthogonal to the traveling direction of the tire. Although the directions match, the lateral direction with a slip angle is shifted by the slip angle. Further, the tire center axis (referred to as the axis CL in FIGS. 14A and 14B) is an axis perpendicular to the road surface that is orthogonal to the tire rotation axis and passes through the tire center.

In the partial models 2 and 3 of the tire dynamic model, more specifically, the following processing is performed.
FIG. 11 shows the processing contents when the slip ratio S in the braking / driving direction is braking, and FIG. 12 shows the processing contents when the slip ratio S in the braking / driving direction is driving.
In the case of braking, the tire dynamic element parameter is composed of nonlinear parameters and linear parameters such as canvas stiffness C _γ , lateral torsional rigidity G _my, belt member lateral bending coefficient ε, coefficient C _q , lateral rigidity K _y and torsional rigidity A _y. The camber angle γ, slip angle α, braking slip ratio S, tire running speed V _r , longitudinal force F _x , lateral force F _y , self-aligning torque M _z , and contact width w , By inputting the contact length l and the distance h, the values of the longitudinal force, lateral force and self-aligning torque calculated according to the equations (1) to (8) in FIG. 11 (hereinafter referred to as the longitudinal force F _x ′, Lateral force F _y ′ and self-aligning torque M _z ′ are calculated). Of course, the tire characteristic calculation unit 10 calculates the input longitudinal force F _x , lateral force F _y and self-aligning torque M _z values, and the calculated longitudinal force F _x ′, lateral force F _y ′ and self-aligning. The longitudinal force F _x , the lateral force F _y, and the self-force only when the error from the value of the torque M _z ′ is equal to or less than a predetermined value, that is, substantially coincides (has converged and the force is balanced in the tire dynamic model). The value of the lining torque _Mz is determined as the value of the longitudinal force, the lateral force, and the torque of the tire that realizes the force balance state.
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 partial model 2 is obtained by the input self-aligning torque M _z and the torsional compliance (1 / G _mz ) as shown in FIG. 13A and further as shown in the equation (1) in FIG. An effective slip angle α _e is calculated by calculating a twist return angle to be obtained and subtracting the twist return angle from the applied slip angle α. FIG. 13A shows a state in which, when the slip angle α is applied, the tire itself acts so as to reduce the slip angle α by the self-aligning torque generated by the slip angle α, and the effective slip angle α _e is obtained. Show. Thus, the effective slip angle α _e is calculated when the slip angle α is relatively small, and the self-aligning torque M _z acts on the tire itself to reduce the applied slip angle α and twist back. It is because it has. Therefore, when the slip angle alpha is relatively small, as shown in FIG. 13 (a), the effective slip angle alpha _e respect actually granted slip angle alpha is small.
Incidentally, FIG. 13 (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. This content is shown in equation (7). FIG. 13C shows that the ground contact surface of the tire moves in the front-rear direction due to the front-rear force. This content is shown in equation (3).

Further, a deflection coefficient q that defines the shape of the contact pressure distribution is calculated from the longitudinal force F _x by the equation (2) in FIG. The deflection coefficient q has a value q ₀ when the longitudinal force F _x is zero. The deflection coefficient q is a contact pressure distribution in a straight traveling state with a slip angle α = 0 (see FIG. 14A). As shown in FIG. 14B, a longitudinal force F _x is generated and the contact pressure distribution advances. 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). The deflection coefficient q is set to 0 when the longitudinal force F _x is 0. This contact pressure distribution is represented by p (t) (t is a coordinate position normalized by the contact length when the t-axis is taken in the backward direction of travel in FIGS. 14 (a) and 14 (b)). 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. 14D, 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 ground contact surface of the tire moves in the front-rear direction due to the generation of the front-rear force F _x is calculated from Equation (3). As shown in FIG. 13 (c), 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 expression (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 model is configured so that the center position moves. This amount of movement (x _c / l) is used in equation (8) for calculating a self-aligning torque M _z described later. Here, l is the ground contact length of the center portion. In this way, the movement of the center position of the ground contact surface of the tire is determined in the equation (3) because the tire deformation near the ground contact during the tire braking is actually performed during braking and during 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. In addition, FIG.13 (d) is a figure which shows the measurement result measured with the laser scanner about the tire shape of 195 / 65R15 91H (internal pressure 230kPa, load 4kN, traveling speed 60km / h).

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. 15A to 15C 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. 15 (a), the region at the stepping-in end side from the boundary position (l _h / l) is an adhesion region where the tire tread member is adhered to the road surface, and the region on the kicking side is the tire tread member relative 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. 15B 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. Further, when the slip angle α is increased, as shown in FIG. 15C, a sliding friction is generated from the position of the stepping end of the ground contact surface.

As can be seen from FIGS. 15 (a) to 15 (c), the ratio of the adhesion area and the sliding area 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 slip region, that is, the lateral force component along the tire width direction, and the moment around the ground contact center of the tire. By calculating, self-aligning 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. As described above, in the partial models 2 and 3, the ground contact surface changes from a rectangular shape to a trapezoidal shape depending on the camber angle γ, but the boundary position (l _h / l) between the adhesion region and the sliding region at that time. ) Does not change in the width direction in the ground plane. That is, the boundary position (l _h / l) is assumed to be constant in the tire width direction.

In the equation (6) in FIG. 11, 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 is calculated using the effective slip angle α _e. The force F _y ′ and torque M _z ′ are calculated. Expressions (6) to (8) include the contact length change rate η depending on the camber angle γ, and the change in the contact shape due to the camber angle γ is taken into consideration. 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.

Next, equations (6) to (8) will be described in more detail.
Formula (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 three terms (three 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. The third term represents the lateral force component of the canvas last. 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 The lateral force component of the canvas last of the third term is the same as the lateral force calculated according to the equation (20) in FIG.

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. The third term is the component that the longitudinal force of the adhesive zone gives to M _z 'due to the trapezoidal shape of the ground contact, and the fourth term is the front and back of the slip zone due to the trapezoidal shape of the ground contact shape. This represents the component that the force gives to M _z '. Furthermore, a fifth term is provided. The fifth term is a term proportional to (l _h / l) · tan α _e , and the ground contact surface of the tire moves laterally by the effective slip angle α _e , and the amount of movement at this time and the adhesion area and slip generated on the tire This represents the torque component around the tire center caused by the longitudinal force in the region. In addition, in any of these terms, the effect that the ground contact shape becomes trapezoidal due to the camber angle γ is included through the contact length change rate η.

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 self-aligning torque M _z ′, respectively. That is, the longitudinal force F _x ′, the lateral force F _y ′, and the self-aligning 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 due to the slip angle α occur simultaneously. Specifically, as shown in FIG. 13 (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 of formulas (6) to (8) and formulas (16) to (18) in FIG. 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 driving, the partial model 3 is used. As shown in FIG. 12, as in the case of braking, dynamic element parameter values including linear parameters and nonlinear parameters are set, slip angle α, camber angle γ, slip ratio S in the braking / driving direction, and tire travel. By inputting the speed V _r , the longitudinal force F _x , the lateral force F _y , the self-aligning torque M _z , the contact length l, the contact width w, and the distance h, the equations (11) to (18) in FIG. The longitudinal force, lateral force and torque values (hereinafter referred to as longitudinal force F _x ′, lateral force F _y ′, and self-aligning torque M _z ′) processed by the above are calculated. Of course, the tire characteristic calculation unit 10 calculates the input longitudinal force F _x , lateral force F _y, and self-aligning torque M _z and the calculated longitudinal force F _x ′, lateral force F _y ′, and self-calculation. Only when the error from the value of the aligning torque M _z ′ is equal to or less than a predetermined value, that is, substantially coincides (converged, the force is balanced in the tire dynamic model), the longitudinal force F _x , the lateral force F _y, and The value of the self-aligning torque _Mz is determined as the value of the lateral force and the self-aligning torque of the tire that realizes the force balance state.

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. 16 shows that the slip angle α, the camber angle γ, the slip ratio S in the braking / driving direction, and the layer conception degree V _r are given, and the longitudinal force F _x ′ and the lateral force F based on the partial models 2 and 3 of the tire dynamic model. It is a processing block diagram until _y 'and cell aligning torque _Mz ' are calculated. As can be seen from FIG. 16, the partial models 2 and 3 of the tire dynamic model have the lateral bending deformation of the belt and the contact pressure when calculating the longitudinal force F _x ′, the lateral force F _y ′, and the cell aligning torque M _z ′. Formulas (6) to (8) or formulas (16) to (18) are fed back by the forward deflection of the distribution and the rearward shift of the ground contact surface, the torsional deformation of the tire sidewall, and the lateral torsional deformation of the ground contact portion. Is calculated in In addition, the lateral bending deformation of the belt used for calculating the longitudinal force F _x ′, the lateral force F _y ′, and the cell aligning torque M _z ′, forward deflection of the contact pressure distribution, rearward shift of the contact surface, tire sidewall The applied longitudinal force F _x , lateral force F _y , and self-aligning torque M _z are used for torsional deformation and lateral torsional deformation in the ground plane. Of course, when calculating the longitudinal force F _x ′, the lateral force F _y ′, and the cell aligning torque M _z ′, as shown in FIG. 3B, the ground contact surface may change to a trapezoidal shape due to the camber angle γ. include.

Note that the longitudinal force F _x ′, lateral force F _y ′ and cell aligning torque M _z ′ calculated by the tire dynamic model calculation unit 12 are the applied longitudinal force F _x , lateral force F _y and self-aligning torque. It does not necessarily match _Mz . However, the longitudinal force F _x , lateral force F _y, and self-aligning torque M _z that are applied and the longitudinal force F _x ′ calculated by the sequence processing performed in the tire characteristic calculation unit 10 or the parameter extraction unit 11, and the lateral force are calculated. The longitudinal force F _x , the lateral force F _y and the self-aligning torque M _z are searched so that F _y ′ and the cell aligning torque M _z ′ substantially coincide (become a force balance state), and the tire dynamic model The front-rear force, the lateral force, and the self-aligning torque in the balanced state are calculated.

FIG. 17 is a diagram illustrating an example of a flow for calculating tire characteristics. This example, by fixing the slip ratio S and the applied load F _z of the braking-driving direction at a constant value, in the example of calculating the characteristic curve representing the longitudinal force, lateral force, and dependence of the slip angle α of the self-aligning torque is there.
First, the tire characteristic calculation unit 12 reads the value of the linear parameter and the value of the nonlinear parameter from the memory 4 and sets the value of each parameter (step S200). The nonlinear parameter includes the value of canvas stiffness C _γ from which the value is extracted by the parameter extraction unit 11 and the value of the lateral torsional rigidity G _{my on} the contact surface. Furthermore, the longitudinal force F _x under the applied load F _z, the value of the lateral force F _y, and self-aligning torque _{M z} is initialized (step S210).

Thereafter, when calculating the characteristic curve representing the slip angle dependency, the tire characteristic calculating unit 10 sets the linear and non-linear parameters, the initial longitudinal force F _x and the lateral force F together with the set slip angle α = Δα. _y and the self-aligning torque M _z and various values are given to the tire dynamic model calculation unit 12. The tire dynamic model calculation unit 12 uses the given linear and non-linear parameters, and the initially set longitudinal force F _x , lateral force F _y, and self-aligning torque M _z to obtain equations (6) to (8) or The longitudinal force F _x ′, lateral force F _y ′, and cell aligning torque M _z ′ are calculated according to the equations (16) to (18) (step S220).

The longitudinal force F _x ′, lateral force F _y ′, and cell aligning torque M _z ′ calculated in this way are returned to the tire characteristic calculator 10. The tire characteristic calculation unit 10 sets the longitudinal force F _x , lateral force F _y, and self-aligning torque M _z applied to the tire dynamic model calculation unit 12 and the calculated longitudinal force F _x ′ and lateral force F _y ′. Then, a square residual sum with the calculated value of the cell aligning torque M _z ′ is calculated (step S230).
Next, the tire characteristic calculation unit 10 determines whether or not the calculated sum of squared residuals is equal to or smaller than a predetermined value (step S240). If it is determined that it has not converged, the set values of the longitudinal force F _x , lateral force F _y , and cell aligning torque M _z set previously are adjusted (step S250). The adjusted longitudinal force F _x , lateral force F _y, self-aligning torque M _z , values of linear parameters and nonlinear parameters are again applied to the tire dynamic model calculation unit 12.

Thus, the tire characteristic calculation unit 10 adjusts the set values of the longitudinal force F _x , the lateral force F _y, and the torque M _z until the sum of squared residuals converges to a predetermined value or less. This set value is adjusted according to, for example, the Newton-Raphson method. Thus, the longitudinal force F _x ′, the lateral force F _y ′, and the cell aligning torque M _z ′ are determined (step S260).

Next, the tire characteristic calculation unit 10 determines whether or not the slip angle α is equal to or less than a predetermined slip angle (step S270). When the tire characteristic calculation unit 10 determines that the slip angle α is equal to or less than the predetermined slip angle, the condition of the slip angle α is changed (α → α + Δα) (step S280). Thereafter, 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 S210), and the longitudinal force F _x ′, lateral force F _y ′, and self-aligning torque are set. M _z ′ is calculated (step S220), a square residual sum is calculated (step S230), and convergence is determined based on the square residual sum (step S240). Thus, the slip angle α is repeatedly changed until the predetermined slip angle is reached (step S270). Each time the slip angle is changed, the tire dynamic model calculation unit 12 calculates the longitudinal force F _x ′, the lateral force F _y ′, and the self-aligning torque M _z ′. The force F _x , lateral force F _y and self-aligning torque M _z are determined. The determined longitudinal force F _x , lateral force F _y and self-aligning torque M _z data are stored in the memory 4 and output to the output device 7.
Such processing is executed in the apparatus 1 using a program.

18 (a), 18 (b) to 20 (a), 20 (b) show the values of the canvas stiffness C _γ from which values are extracted by the parameter extraction unit 11 and the values of the lateral torsional rigidity G _my of the contact surface, Using the values of the other tire dynamic element parameters stored in the memory 4, the slip angle α is set to −20 under the conditions of the camber angle γ = 0 degrees, the camber angle γ = + 4 degrees, and the camber angle γ = -4 degrees. This is a result of calculating the lateral force _Fy and the self-aligning torque _Mz by setting in the range of degrees to +20 degrees. The value of the tire dynamic element parameter stored in the memory 4 is acquired in advance at the camber angle γ = 0. The values of the tire dynamic element parameters other than the value of the canvas stiffness C _{γ and} the value of the lateral torsional rigidity G _my of the contact surface can be obtained in advance using, for example, a method described in Japanese Patent Application Laid-Open No. 2008-49725. it can.

In the examples shown in FIGS. 18A, 18B to 20A, 20B, a 205 / 50R16 89V tire is operated with an air pressure of 230 kPa, a load load of 5.72 kN, a running speed of 80 km / hour, and a slip ratio S = The values of tire dynamic element parameters were obtained from experimental data (slip angle dependency data) of tire characteristics obtained by measurement under the conditions of 0 and camber angle γ = 0. The method of acquiring the value of the tire dynamic element parameter was performed using the method described in Japanese Patent Application Laid-Open No. 2008-49725. Furthermore, from the experimental data of the tire characteristics indicating the camber angle dependency of the canvas last obtained by changing the camber angle γ under the conditions of the slip angle α = 0 and the slip ratio S = 0, the value of the canvas stiffness C _γ and extracts the value of the torsional rigidity _{G my.} Using the values of the tire dynamic element parameters including the extracted canvas stiffness C _γ and the lateral torsional rigidity G _my , the lateral force F _y and the self-aligning torque M _z under the conditions of the camber angle γ = 0 and ± 4 degrees. Was calculated. Such tire characteristic calculation results are stored in the memory 4 and further output to the output device 7. In the figure, “+” is experimental data, and the tire characteristic calculation results obtained by the tire characteristic calculator 10 are indicated by solid lines.

According to FIGS. 18 (a), 18 (b) to 20 (a), 20 (b), when the camber angle γ = 0, both the lateral force F _y and the self-aligning torque M _z are very good in the experimental data (measured values). It can be seen that they are approximate. It can be seen that when the camber angle γ = ± 4 degrees, the slip angle α, which is important as a tire characteristic, is approximated to experimental data relatively well in the range of −5 degrees to +5 degrees.

21 (a) to 21 (c), respectively, acquire the values of the tire dynamic element parameters by the same method as in the examples of FIGS. 18 (a), (b) to 20 (a), (b), and angle gamma = 0, + 4 °, a diagram summarizing the data of the lateral force F _y, and longitudinal force F _x in -4 degrees. Such tire characteristic calculation results are stored in the memory 4 and output to the output device 7.

  Thus, as shown in FIG. 7B, the apparatus 1 uses the modified camber angle in which the applied camber angle is corrected according to the lateral force, thereby performing an experiment on the camber angle dependency of the canvas last. The data can be reproduced well. For this reason, the apparatus 1 can calculate tire characteristics (cornering characteristics, braking / driving characteristics, and composite characteristics thereof) under a condition in which a camber angle is given, with relatively good reproduction, using a tire dynamic model.

  The tire lateral force calculation method and apparatus, the tire stiffness parameter value extraction method and apparatus, the tire characteristic calculation method and apparatus, and the program according to the present invention have been described above in detail, but the present invention is limited to the above-described embodiment. Needless to say, various improvements and modifications may be made without departing from the spirit of the present invention.

1 Device 2 CPU
3 Bus 4 Memory 5 Input operation system 6 Interface 7 Output device 8 Module group 9 Setting unit 10 Tire characteristic calculation unit 11 Parameter extraction unit 12 Tire dynamic model calculation unit 13 Vehicle simulation unit 14 Integration / management unit

Claims (14)

A calculation method for calculating a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground,
Setting a camber stiffness parameter value used in a tire dynamic model capable of calculating a lateral force;
Calculating a lateral force in accordance with the tire dynamic model using the value of the set camber stiffness parameter and a given camber angle, and
The tire dynamic model uses the corrected camber angle in which the applied camber angle is corrected according to the lateral force when calculating the lateral force.   The correction amount used to obtain the corrected camber angle from the assigned camber angle is an amount proportional to the rate of change in the tire width direction of the tire contact length at the assigned camber angle and proportional to the lateral force. The tire lateral force calculation method according to claim 1, wherein In a tire dynamic model for calculating a lateral force acting on a tire when a camber angle is given to a tire rolling on the ground, a camber stiffness parameter value used for calculating the lateral force is extracted. And
Obtaining experimental data representing a relationship between a given camber angle and a lateral force generated by the camber angle;
Extracting a value of a camber stiffness parameter used in a tire dynamic model capable of calculating a lateral force using the experimental data;
Outputting the value of the extracted camber stiffness parameter,
The tire dynamic model uses a modified camber angle in which the assigned camber angle is modified in accordance with the lateral force, and extracts a tire stiffness parameter value.   The correction amount used to obtain the corrected camber angle from the assigned camber angle is an amount proportional to the rate of change in the tire width direction of the tire contact length at the assigned camber angle and proportional to the lateral force. The method for extracting the value of the tire stiffness parameter according to claim 3. A computer-executable program for causing a computer to calculate a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground,
A procedure for causing the computer to set the value of the camber stiffness parameter used in the tire dynamic model capable of calculating the lateral force;
A step of causing the computer to calculate and output a lateral force according to the tire dynamic model using the value of the set camber stiffness parameter and a given camber angle, and
When the lateral force is calculated using the tire dynamic model, a modified camber angle obtained by correcting the applied camber angle according to the lateral force is used. A calculation device for calculating a lateral force acting on a tire when a camber angle is given to the tire rolling on the ground,
A setting unit for setting a value of a camber stiffness parameter used in a tire dynamic model capable of calculating a lateral force;
A calculation unit that calculates a lateral force according to the tire dynamic model using the value of the set camber stiffness parameter and a given camber angle;
When calculating the lateral force, the calculation unit uses a corrected camber angle in which the applied camber angle is corrected in accordance with the lateral force. In a tire dynamic model for calculating a lateral force acting on a tire when a camber angle is given to a tire that rolls on the ground, a computer extracts a value of a camber stiffness parameter used to calculate the lateral force A computer-executable program,
A procedure for causing a computer to acquire experimental data representing a relationship between a given camber angle and a lateral force generated by the camber angle;
A procedure for causing the computer to extract the value of the camber stiffness parameter used in the tire dynamic model capable of calculating the lateral force, using the experimental data;
And a procedure for outputting the extracted camber stiffness parameter value,
The tire dynamic model uses a modified camber angle in which the assigned camber angle is modified according to the lateral force. In a tire dynamic model for calculating a lateral force acting on a tire when a camber angle is given to a tire rolling on the ground, an apparatus for extracting a value of a camber stiffness parameter used when calculating the lateral force There,
A data acquisition unit that acquires experimental data representing the relationship between the assigned camber angle and the lateral force generated by the camber angle;
An extraction unit for extracting the value of the camber stiffness parameter used by the tire dynamic model capable of calculating the lateral force using the experimental data;
An output unit that outputs the value of the extracted camber stiffness parameter;
The tire dynamic model uses a corrected camber angle in which the assigned camber angle is corrected in accordance with the lateral force, and the tire stiffness parameter value extracting apparatus. A tire characteristic calculation method for calculating cornering characteristics and / or braking / driving characteristics of a tire under a condition in which a camber angle is given based on a tire dynamic model using a plurality of tire dynamic element parameters,
Setting a value of a tire dynamic element parameter used in the tire dynamic model;
Calculating cornering characteristics and / or braking / driving characteristics according to the tire dynamic model using the set tire dynamic element parameter values,
The tire characteristic calculation method according to claim 3, wherein the tire dynamic element parameter includes a tire stiffness parameter extracted by the method according to claim 3.   The tire according to claim 9, wherein when calculating the cornering characteristic and / or braking / driving characteristic, a modified camber angle in which the applied camber angle is corrected according to the lateral force is used in the tire dynamic model. Characteristic calculation method. A computer-executable program for causing a computer to calculate cornering characteristics and / or braking / driving characteristics of a tire under a condition in which a camber angle is given based on a tire dynamic model using a plurality of tire dynamic element parameters,
A procedure for causing the computer to set the values of the tire dynamic element parameters used by the tire dynamic model;
Using the set value of the tire dynamic element parameter to cause the computer to calculate and output cornering characteristics and / or braking / driving characteristics according to the tire dynamic model, and
The program according to claim 3, wherein the tire dynamic element parameter includes a tire stiffness parameter extracted by the method according to claim 3 or 4. An apparatus for calculating cornering characteristics and / or braking / driving characteristics of a tire under a condition in which a camber angle is given based on a tire dynamic model using a plurality of tire dynamic element parameters,
A setting unit for setting a value of the tire dynamic element parameter;
A calculation unit that calculates cornering characteristics and / or braking / driving characteristics according to the tire dynamic model using the set tire dynamic element parameter values;
The tire characteristic calculation device according to claim 3, wherein the tire dynamic element parameter includes a tire stiffness parameter extracted by the method according to claim 3 or 4. An evaluation step for evaluating cornering characteristics and / or braking / driving characteristics calculated by the tire characteristic calculation method according to claim 9 or 10,
And a design step of changing a tire shape or a tire constituent member that realizes the value of the tire dynamic element parameter in accordance with the evaluation result. Obtaining a cornering characteristic and / or a braking / driving characteristic calculated by the tire characteristic calculating method according to claim 9 or 10,
Applying a cornering characteristic and / or a braking / driving characteristic to a vehicle model reproducing the vehicle, and analyzing a movement characteristic of the vehicle.