JP2022047824A - Simulation method and device of tire - Google Patents

Abstract

To provide a simulation method etc. which can calculate a travel state of a tire with high precision.SOLUTION: The simulation method of a tire comprises a simulation step of causing, by a computer, a tire model to travel on a road surface model. The simulation step comprises: a first step S21 of determining an initial friction coefficient in a contact part of the tire model and the road surface model; a second step S22 of calculating a plurality of physical quantities of the tire model during travel by using the initial friction coefficient; a third step S23 of changing the initial friction coefficient on the basis of at least one of the plurality of physical quantities calculated at the second step S22; and a fourth step S24 of calculating the plurality of physical quantities of the tire model during travel by using the changed friction coefficient.SELECTED DRAWING: Figure 5

Description

The present invention relates to a tire simulation method and the like.

The following Patent Document 1 describes a simulation method for grounding and rolling a tire FEM model in which a tire is divided into a plurality of elements with a predetermined load. In this method, the three-component force generated on the ground contact surface is calculated for each element based on the coefficient of friction, and the lateral force or cornering force applied to the tire shaft is calculated.

Japanese Unexamined Patent Publication No. 2018-96783

In recent years, the running performance of tires has been evaluated more severely. Therefore, even in the tire running simulation, a more accurate calculation result is required, but the above method has room for further improvement in the accuracy of the calculation result.

The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a simulation method or the like capable of calculating a running state of a tire with high accuracy.

The present invention is a method for simulating a tire, in which a step of inputting a tire and a road surface into a computer as a tire model and a road surface model modeled by a finite number of elements, respectively, and a process in which the computer inputs the tire model to the road surface. The simulation step includes a simulation step of running on the model, and the simulation step uses the first step of defining the initial friction coefficient at the contact portion between the tire model and the road surface model and the running using the initial friction coefficient. A second step of calculating a plurality of physical quantities of the tire model in the tire model, and a third step of changing the initial friction coefficient based on at least one of the plurality of physical quantities calculated in the second step. It is characterized by including a fourth step of calculating the plurality of physical quantities of the running tire model using the changed friction coefficient.

In the tire simulation method according to the present invention, the third step and the fourth step may be repeated every minute time.

In the tire simulation method according to the present invention, the plurality of physical quantities include at least one of the contact pressure at the contact portion, the slip speed at the contact portion, and the temperature of the tire model, and the third step is described. , The initial coefficient of friction may be varied based on at least one of the ground pressure, the slip speed, and the temperature.

In the tire simulation method according to the present invention, the third step may change the initial coefficient of friction based on at least two of the contact pressure, the slip speed, and the temperature.

In the tire simulation method according to the present invention, the plurality of physical quantities may further include the calorific value of the tire model, and the temperature may be calculated in consideration of the calorific value.

The tire simulation method according to the present invention further includes a step of inputting the temperature distribution of the running tire into the computer prior to the simulation step, and the temperature is obtained in consideration of the temperature distribution. You may.

In the tire simulation method according to the present invention, the plurality of physical quantities may further include at least one of the front-rear force and the lateral force of the tire model.

The present invention is a device including a calculation processing device for executing a tire simulation, and the calculation processing device sets a tire and a road surface as a tire model and a road surface model modeled by a finite number of elements, respectively. The model setting unit and the simulation calculation unit for running the tire model on the road surface model are included, and the simulation calculation unit defines an initial friction coefficient at a contact portion between the tire model and the road surface model. 1 calculation unit, a second calculation unit that calculates a plurality of physical quantities of the tire model in running using the initial friction coefficient, and at least one of the plurality of physical quantities calculated by the second calculation unit. Includes a third calculation unit that changes the initial friction coefficient and a fourth calculation unit that calculates the plurality of physical quantities of the running tire model using the changed friction coefficient. It is a feature.

By adopting the above process, the tire simulation method of the present invention can calculate the running state of the tire with high accuracy.

It is a block diagram which shows an example of the computer (tire simulation apparatus) which executes the tire simulation method. It is a flowchart which shows an example of the processing procedure of the tire simulation method. It is a perspective view which shows an example of a tire model and a road surface model. It is sectional drawing which shows an example of a tire model. It is a flowchart which shows an example of the processing procedure of a simulation process. It is a figure which shows an example of a friction coefficient table. It is a flowchart which shows an example of the processing procedure of the simulation method of another Embodiment of this invention. It is a figure which shows an example of the temperature distribution of a tire.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that each drawing is for enhancing the understanding of the content of the invention, and it is pointed out in advance that the scales and the like do not exactly match between the drawings, in addition to the exaggerated display.

[Tire simulation method (first embodiment)]
In the tire simulation method of the present embodiment (hereinafter, may be simply referred to as a "simulation method"), the running state of the tire is calculated using a computer. FIG. 1 is a block diagram showing an example of a computer (tire simulation device) in which a tire simulation method is executed.

[Tire simulation device]
The computer 1 of the present embodiment is configured as a tire simulation device (hereinafter, may be simply referred to as a “simulation device”) 1A. The computer 1 of the present embodiment includes an input unit 2 as an input device, an output unit 3 as an output device, and an arithmetic processing unit 4 for calculating a physical quantity of a tire and the like.

As the input unit 2, for example, a keyboard, a mouse, or the like is used. As the output unit 3, for example, a display device, a printer, or the like is used. The arithmetic processing device 4 includes an arithmetic unit (CPU) 4A for performing various arithmetic operations, a storage unit 4B for storing data, programs, and the like, and a working memory 4C.

The storage unit 4B is a non-volatile information storage device including, for example, a magnetic disk, an optical disk, an SSD, or the like. The storage unit 4B is provided with a data unit 5 and a program unit 6.

The data unit 5 includes an initial data unit 5A in which information about the tire to be evaluated and the road surface (for example, CAD data) is stored, and a model input unit 5B in which the tire model and the road surface model are input. Further, the data unit 5 includes a condition input unit 5C into which the boundary conditions and the like of the simulation are input, and a physical quantity input unit 5D in which the physical quantity and the like calculated by the calculation unit 4A are input.

The program unit 6 is a program executed by the arithmetic unit 4A. The program unit 6 includes a model setting unit 6A for setting a tire model and a road surface model, and a simulation calculation unit 6B for running the tire model on the road surface model. Further, the program unit 6 of the present embodiment includes a performance evaluation unit 6C for evaluating the running performance of the tire (tire model) to be analyzed.

The simulation calculation unit 6B includes a first calculation unit 7, a second calculation unit 8, a third calculation unit 9, and a fourth calculation unit 10. Further, the simulation calculation unit 6B of the present embodiment further includes an end determination unit 11. The functions of the first calculation unit 7 to the fourth calculation unit 10 and the end determination unit 11 will be described in each step described later in the simulation method.

[Tire model and road surface model input process]
FIG. 2 is a flowchart showing an example of a processing procedure of a tire simulation method. In the simulation method of the present embodiment, first, the tire and the road surface are input to the computer 1 as a tire model and a road surface model modeled by a finite number of elements, respectively (step S1).

In step S1 of the present embodiment, first, as shown in FIG. 1, information about the tire and the road surface (for example, contour data and the like) input to the initial data unit 5A is input to the working memory 4C. Further, the model setting unit 6A is read into the working memory 4C. Then, the model setting unit 6A is executed by the calculation unit 4A.

FIG. 3 is a perspective view showing an example of the tire model 13 and the road surface model 14. FIG. 4 is a cross-sectional view showing an example of the tire model 13. Note that, in FIG. 3, the tire model 13 is shown in a simplified manner, and the tread pattern of the tread portion 13a, the element F (i) shown in FIG. 4, and the like are omitted.

The tire model 13 is a model of a tire (not shown) to be analyzed. It does not matter whether the tire to be analyzed actually exists or not. Examples of tires to be analyzed include pneumatic tires for passenger cars, but tires for heavy loads such as trucks and buses, and tires of other categories such as airless tires may be used.

As shown in FIG. 4, in the tire model 13, for example, the tire to be analyzed (not shown) has a finite number of elements F (i) (i = 1, 2, ...) That can be handled by the numerical analysis method. It can be defined by being modeled (discretized).

As the numerical analysis method, for example, a finite element method, a finite volume method, a difference method, or a boundary element method (in this embodiment, the finite element method) can be appropriately adopted. For the element F (i), for example, a three-dimensional tetrahedral solid element, a pentahedral solid element, a hexahedral solid element, or the like is used. Each element F (i) is configured to include a plurality of nodes 15. Each element F (i) includes an element number, a node number 15, a coordinate value of the node 15, material properties (for example, density, Young's modulus, attenuation coefficient, thermal conductivity, heat transfer coefficient, etc.) and the like. Numerical data is defined.

In step S1, for example, the rubber portion including the tread rubber of the tire to be analyzed (not shown), the carcass ply forming the skeleton of the tire, and the belt ply arranged on the outer side of the carcass ply in the radial direction of the tire are elements F. Each is discretized (modeled) in (i). As a result, a rubber member model (for example, a tread rubber model) 16, a carcass ply model 17, and a belt ply model 18 are set in the tire model 13.

As shown in FIG. 3, in step S1, the road surface has a finite number of elements G (i) that can be handled by the numerical analysis method (in this embodiment, the finite element method) based on the information on the road surface (not shown). ) (I = 1, 2, ...) To be discretized. As a result, in step S1, a road surface model 14 that models the road surface is set.

The element G (i) is defined as an indeformably defined rigid plane element. The element G (i) is provided with a plurality of nodes 19. Further, in the element G (i), numerical data such as an element number and a coordinate value of a node 19 is defined.

In this embodiment, a road surface model 14 having a smooth surface is defined, but the present invention is not limited to such an embodiment. For example, a road surface model 14 (not shown) may be defined in which minute irregularities such as an asphalt road surface, irregular steps, dents, swells, or irregularities similar to an actual running road surface such as ruts are provided. The tire model 13 and the road surface model 14 are stored in the model input unit 5B (that is, the computer 1).

[Simulation process]
Next, in the simulation method of the present embodiment, the computer 1 runs the tire model 13 on the road surface model 14 (simulation step S2).

In the simulation step S2 of the present embodiment, first, as shown in FIG. 1, the tire model 13 and the road surface model 14 (shown in FIG. 3) stored in the model input unit 5B are read into the working memory 4C. .. Further, the boundary condition (including the internal pressure condition and the load condition) stored in the condition input unit 5C and the simulation calculation unit 6B (including the first calculation unit 7 to the fourth calculation unit 10 and the end determination unit 11) , Read into the working memory 4C. Then, the simulation calculation unit 6B is executed by the calculation unit 4A.

By the way, in a running tire, for example, the coefficient of friction with the road surface changes from moment to moment due to the influence of physical quantities such as ground pressure. It is desirable that such a change in the coefficient of friction be taken into consideration in the calculation of the running state of the tire using the computer 1. In the simulation step S2 of the present embodiment, the state in which the tire model 13 is run on the road surface model 14 is calculated in consideration of the change in the friction coefficient. FIG. 5 is a flowchart showing an example of the processing procedure of the simulation step S2.

[First step]
In the simulation method of the present embodiment, first, the initial friction coefficient at the contact portion 21 between the tire model 13 and the road surface model 14 is defined (first step S21). In the first step S21, the first calculation unit 7 included in the simulation calculation unit 6B shown in FIG. 1 is executed by the calculation unit 4A. The first calculation unit 7 is for defining the initial friction coefficient in the contact portion 21 between the tire model 13 and the road surface model 14 shown in FIG.

In the first step S21 of the present embodiment, first, as shown in FIG. 4, the bead portions 13c and 13c of the tire model 13 are restrained by the rim model 22 that models the tire rim (not shown). Then, the deformation of the tire model 13 is calculated based on the evenly distributed load w corresponding to the internal pressure condition (included in the boundary condition). As a result, in the first step S21, the tire model 13 after the internal pressure filling is calculated. Internal pressure conditions can be set as appropriate. For example, in a standard system including a standard on which a tire is based, it is desirable that the air pressure defined for each tire by each standard is set as an internal pressure condition.

The deformation calculation (including the rolling calculation described later) of the tire model 13 is based on the shape and material properties of each element F (i), and the mass matrix, rigidity matrix, and damping of each element F (i). Each matrix is created. Furthermore, each of these matrices is combined to form the matrix of the entire system. Then, the equations of motion are created by applying the various conditions, and these are calculated for each minute time (unit time) T (x) (x = 0, 1, ...). As a result, the deformation calculation of the tire model 13 is performed. The length of the minute time is appropriately set (for example, 1 μsec) based on the required simulation accuracy.

For the deformation calculation of the tire model 13 (including the rolling calculation described later), for example, commercially available finite element analysis application software such as LS-DYNA manufactured by LSTC is used. The minute time T (x) is appropriately set according to the required simulation accuracy.

Next, in the first step S21 of the present embodiment, as shown in FIG. 3, the tire model 13 after the internal pressure filling is brought into contact with the road surface model 14. Similar to the conventional simulation, conditions for preventing slip-through (conditions different from the initial friction coefficient in the present embodiment) are predefined between the tire model 13 and the road surface model 14.

Next, in the first step S21 of the present embodiment, the deformation of the tire model 13 is calculated based on the load condition L and the camber angle (included in the boundary condition). As a result, in the first step S21, the tire model 13 after the load applied to the road surface model 14 is calculated.

The load condition L can be set as appropriate. For example, in a standard system including a standard on which a tire is based, it is desirable that the normal load defined for each tire by each standard is set as the load condition L.

Then, in the first step S21 of the present embodiment, the initial friction coefficient is defined in the contact portion 21 (shown in FIG. 3) between the tire model 13 and the road surface model 14. In the present embodiment, the initial coefficient of friction is defined for each element F (i) constituting the contact portion 21. The initial coefficient of friction can be specified as appropriate. In the first step S21 of the present embodiment, the initial friction coefficient is acquired by using a predetermined friction coefficient table. FIG. 6 is a diagram showing an example of the friction coefficient table 23.

The coefficient of friction table 23 shows the relationship between the coefficient of friction and the physical quantity (having a dependency) that affects the coefficient of friction. As this physical quantity, one that affects the coefficient of friction is appropriately selected. The physical quantity of the present embodiment includes at least one of the contact pressure at the contact portion 21 (shown in FIG. 3), the slip speed at the contact portion 21, and the temperature of the tire model 13.

In FIG. 6, a plurality of small tables 24 showing the relationship between the contact pressure, the slip speed, and the friction coefficient are provided for each temperature of the tire model 13. In each small table 24, the value on the vertical axis is the ground pressure, and the value on the horizontal axis is the slip speed. The values corresponding to the vertical axis and the horizontal axis are the friction coefficient.

The aggregate of the small tables 24 set for each temperature of the tire model 13 shows the relationship between the contact pressure at the contact portion 21, the slip speed at the contact portion 21, the temperature of the tire model 13, and the friction coefficient. The friction coefficient table 23 is configured. In such a friction coefficient table 23, by specifying the contact pressure, the sliding speed, and the temperature, the friction coefficient corresponding to those physical quantities can be uniquely obtained.

The coefficient of friction table 23 can be obtained as appropriate. In the present embodiment, in order to acquire the friction coefficient table 23, first, a rubber piece (not shown) having the same composition as the tread rubber of the tire to be evaluated is acquired. Next, the coefficient of friction is measured under a plurality of conditions in which the combination of physical quantities (ground pressure of the rubber piece, sliding speed of the rubber piece, and temperature of the rubber piece) given to the rubber piece is different. As a result, the coefficient of friction table 23 can be obtained. The friction coefficient table 23 may be obtained by a simulation by a computer 1 instead of the actual measurement using a rubber piece.

The friction coefficient table 23 of the present embodiment shows the contact pressure at the contact portion 21, the slip speed at the contact portion 21, and the tire model 13 as physical quantities (affecting the friction coefficient) for specifying the friction coefficient. All, but not limited to, such aspects. Of these physical quantities, those containing at least one physical quantity may be included. In order to accurately specify the coefficient of friction, it is desirable to include at least two physical quantities of these contact pressures, slip speeds and temperatures, and it is further desirable to include all of these physical quantities. Further, apart from these physical quantities (ground pressure, slip speed and temperature), the friction coefficient table 23 may be acquired based on other physical quantities that affect the friction coefficient.

Further, instead of the friction coefficient table 23, a friction coefficient function may be obtained. This friction coefficient function is for obtaining the friction coefficient by using, for example, physical quantities (in this example, contact pressure, sliding speed and temperature) as variables, and is approximate (fitting) to the physical quantities and friction coefficient of the friction coefficient table 23. It can be obtained by letting it. By obtaining such a friction coefficient function, it is possible to supplement and obtain a friction coefficient that has not actually been measured.

In the present embodiment, the friction coefficient table 23 (or the friction coefficient function) is obtained before the simulation method is implemented, and is stored in advance in the condition input unit 5C (shown in FIG. 1). Then, at the start of the first step S21, the friction coefficient table 23 is read into the working memory 4C (shown in FIG. 1).

Then, in the first step S21 of the present embodiment, the initial friction coefficient in the contact portion 21 (shown in FIG. 3) is defined based on the friction coefficient table 23 (shown in FIG. 6). The initial coefficient of friction of the present embodiment is obtained for each element F (i) (shown in FIG. 4) constituting the contact portion 21.

The initial coefficient of friction of each element F (i) corresponds to the physical quantity of each element F (i) (in this embodiment, the contact pressure, the sliding speed, and the temperature) in the friction coefficient of the friction coefficient table 23. Specified by the coefficient of friction. The physical quantity of each element F (i) for specifying the friction coefficient is, for example, based on the angular velocity V1 (running velocity V3) of the tire model 13 and the temperature condition of the outside air (both are included in the boundary condition). Any value can be set respectively. Further, when the friction coefficient of the tire in a stationary state (non-rolling state) is specified as the initial friction coefficient, the slip speed may be set to zero. The specified initial coefficient of friction is stored in the physical quantity input unit 5D (shown in FIG. 1).

[Second step]
Next, in the simulation method of the present embodiment, a plurality of physical quantities of the running tire model 13 (shown in FIG. 3) are calculated using the initial friction coefficient (second step S22). In the second step S22, the second calculation unit 8 included in the simulation calculation unit 6B shown in FIG. 1 is executed by the calculation unit 4A. The second calculation unit 8 is for calculating a plurality of physical quantities of the running tire model 13 by using the initial friction coefficient.

In the second step S22 of the present embodiment, as shown in FIG. 3, the angular velocity V1 is set on the rotating shaft 25 of the tire model 13. Further, a translational speed V2 is set in the road surface model 14. These angular velocities V1 and translational velocities V2 are set based on predetermined traveling velocities V3 (included in the boundary conditions). As a result, the tire model 13 traveling (straight ahead) on the road surface model 14 is calculated. By defining the slip angle, lateral force, etc. (not shown) in the tire model 13, the tire model 13 during turning may be calculated.

In the second step S22 of the present embodiment, after the calculation of the running tire model 13 is started (after the angular velocity V1 and the translational velocity V2 are set in the stationary tire model 13), one minute time (for example, after the translational velocity V2 is set). The running tire model 13 after 1 μsec) has passed is calculated. The running tire model 13 (that is, the tire model 13 after one minute time has elapsed) is running on the road surface model 14 based on the initial coefficient of friction. Then, a plurality of physical quantities (that is, a plurality of physical quantities using the initial friction coefficient) are calculated from the calculated running tire model 13.

The plurality of physical quantities calculated in the second step S22 can be appropriately set. In the present embodiment, a physical quantity that affects the friction coefficient in order to change the initial friction coefficient in the next third step S23 (in this embodiment, the contact pressure at the contact portion 21 and the slip speed at the contact portion 21). , And the temperature of the tire model 13). These physical quantities are obtained for each element F (i) of the contact portion 21 in the tire model 13 in which the running state is calculated using the initial friction coefficient. The ground pressure, slip speed, and temperature can be appropriately calculated based on, for example, the above-mentioned Patent Document 1 and the description of the conventional simulation method. These physical quantities can be appropriately calculated by using, for example, the above-mentioned application software.

In order to calculate the temperature of the tire model 13 with high accuracy, it is important to consider the calorific value of the tire model 13 (tire). Therefore, the plurality of physical quantities calculated by the running tire model 13 may include the calorific value of the tire model 13. As a result, in the simulation step S2, the temperature of the tire model 13 can be calculated in consideration of the calorific value of the tire model 13.

In the present embodiment, for example, as in the conventional simulation method, each element F is used by using the strain of each element F (i) of the tire model 13 in the running state and the loss tangent tan δ of each element F (i). The calorific value of (i) is calculated. Further, the frictional energy of the contact portion 21 may be further considered in the calculation of the calorific value. The calculation of such a calorific value can be appropriately calculated using the above application software.

Further, in order to calculate the temperature of the tire model 13 with high accuracy, it is desirable to consider not only the heat generation amount of the tire model 13 but also the heat dissipation amount of the tire model 13 (tire). In the present embodiment, for example, the heat transfer coefficient, the temperature of the outside air, and each element F set on the outer surface of the tire model 13 and the inner surface of the tire, respectively, based on the same procedure as in Japanese Patent Application Laid-Open No. 2017-226392. The amount of heat released from each element F (i) is calculated using the thermal conductivity of (i) and the like.

In the present embodiment, the heat balance of the heat generation amount and the heat dissipation amount of each element F (i) is calculated, so that, for example, the tire model 13 does not need to execute a fluid simulation modeling air (fluid). The temperature (including the temperature of the contact portion 21) can be calculated in a short time.

In the present embodiment, in order to predict (evaluate) the running performance of the tire (tire model 13) to be analyzed, it is desirable that at least one of the front-rear force and the lateral force of the tire model 13 is included as a plurality of physical quantities. .. The front-rear force and lateral force of the tire model 13 can be appropriately calculated by using the above application software as in the conventional simulation. The plurality of physical quantities calculated in the second step are stored in the physical quantity input unit 5D (shown in FIG. 1).

[Third step]
Next, in the simulation step S2 of the present embodiment, the initial friction coefficient is changed based on at least one of the plurality of physical quantities calculated in the second step (third step S23). In the third step S23, the third calculation unit 9 included in the simulation calculation unit 6B shown in FIG. 1 is executed by the calculation unit 4A. The third calculation unit 9 is for changing the initial friction coefficient based on at least one of the plurality of physical quantities calculated by the second calculation unit 8.

In the third step S23 of the present embodiment, the initial friction calculation is changed in each element F (i) (shown in FIG. 4) constituting the contact portion 21 shown in FIG. In the present embodiment, the physical quantities calculated in the second step S22 (ground pressure at the contact portion 21, slip speed at the contact portion 21, and temperature of the tire model 13) and the friction coefficient table 23 shown in FIG. 6 And are used. Then, among the friction coefficients of the friction coefficient table 23, the friction coefficient that matches the physical quantity (ground pressure, slip speed, and temperature) of each element F (i) is used as a new friction coefficient of each element F (i). , Each updated (changed). The changed coefficient of friction is stored in the physical quantity input unit 5D (shown in FIG. 1).

[Fourth step]
Next, in the simulation step S2 of the present embodiment, a plurality of physical quantities of the running tire model 13 are calculated using the changed friction coefficient (fourth step S24). In the fourth step S24, the fourth calculation unit 10 included in the simulation calculation unit 6B shown in FIG. 1 is executed by the calculation unit 4A. The fourth calculation unit 10 is for calculating a plurality of physical quantities of the running tire model 13 by using the changed friction coefficient.

The plurality of physical quantities calculated in the fourth step S24 can be appropriately set. In the fourth step S24 of the present embodiment, the same physical quantity as that calculated in the second step S22 can be calculated.

In the fourth step S24, one minute from the running tire model 13 calculated in the previous step (before the next step S25 is executed, the second step S22) based on the changed coefficient of friction. A running tire model 13 over time (eg, 1 μsec) is calculated. Then, a plurality of physical quantities (that is, a plurality of physical quantities using the changed coefficient of friction) are calculated from the calculated running tire model 13 (that is, the tire model 13 after one minute time has elapsed). Will be done.

In the simulation step S2 of the present embodiment, the initial friction coefficient is changed (third step S23) based on a plurality of physical quantities (second step S22) calculated using the initial friction coefficient, and the changed friction. A plurality of physical quantities are calculated using the coefficients (4th step S24). Therefore, in the simulation step S2, the physical quantity can be calculated in consideration of the change in the friction coefficient that changes from moment to moment, so that the running state of the tire model 13 can be calculated with high accuracy. The plurality of physical quantities calculated in the fourth step are stored in the physical quantity input unit 5D (shown in FIG. 1).

[End judgment process]
Next, in the simulation step S2 of the present embodiment, it is determined whether or not the predetermined end condition is satisfied (step S25). In step S25, the end determination unit 11 included in the simulation calculation unit 6B shown in FIG. 1 is executed by the calculation unit 4A. The end determination unit 11 is for determining whether or not the end condition is satisfied.

The end condition can be set as appropriate. For this end condition, for example, the total number of rotations of the tire model 13, the calculation end time, and the like are set.

When it is determined in step S25 that the end condition is satisfied (“Y” in step S25), a series of processes in simulation step S2 is completed, and the next step S3 (shown in FIG. 2) is carried out. On the other hand, if it is determined in step S25 that the end condition is not satisfied (“N” in step S25), the third step S23, the fourth step S24, and the step S25 are carried out again.

In the third step S23 to be carried out again, the coefficient of friction changed in the previous third step S23 is further changed based on at least one of the plurality of physical quantities calculated in the fourth step S24. Then, in the fourth step S24 to be carried out next, a plurality of physical quantities of the running tire model 13 are calculated using the friction coefficient further changed in the third step S23.

As described above, in the simulation step S2 of the present embodiment, the third step S23 and the fourth step S24 are repeated every minute time (for example, 1 μsec). Therefore, in the simulation step S2, it is possible to calculate a plurality of physical quantities of the running tire model 13 while changing the friction coefficient every minute time. As a result, in the simulation step S2 of the present embodiment, it is possible to consider the friction coefficient that changes from moment to moment under the influence of physical quantities such as the contact pressure, as in the case of the actual tire friction coefficient. Therefore, in the simulation method (simulation device 1A) of the present embodiment, it is possible to calculate the transient response of the front-back force and the lateral force that change from moment to moment together with the friction coefficient, and a more accurate calculation result can be obtained.

Next, in the simulation method of the present embodiment, as shown in FIG. 2, it is determined whether or not the running performance of the tire to be analyzed (the tire model 13 shown in FIG. 3) is good (step S3). .. In step S3, first, as shown in FIG. 1, the physical quantity of the tire model 13 stored in the physical quantity input unit 5D (in this embodiment, at least one of the front-rear force and the lateral force of the tire model) is worked. It is input to the memory 4C. Further, the performance evaluation unit 6C is read into the working memory 4C. Then, the performance evaluation unit 6C is executed by the calculation unit 4A.

In step S3, it can be appropriately determined whether or not the running performance of the tire (tire model 13) to be analyzed is good. For example, the quality of the running performance can be determined by comparing the physical quantity of the tire model 13 (in the present embodiment, the front-rear force and the lateral force of the tire model) with a predetermined threshold value for the physical quantity. The threshold value can be appropriately set based on the running performance and the like required for the tire to be analyzed.

When it is determined in step S3 that the running performance of the tire to be analyzed (tire model 13) is good (“Y” in step S3), the tire design factor (information about the tire) used to create the tire model 13 is used. ), The tire is designed and manufactured (step S4). On the other hand, when it is determined in step S3 that the running performance of the tire to be analyzed (tire model 13) is not good (“N” in step S3), at least one of the tire design factors is changed (step S5). Steps S1 to S3 are carried out again.

As described above, in the simulation method of the present embodiment, the tire design factor is changed until the running performance is judged to be good, so that the tire having good running performance can be reliably designed and manufactured.

[Tire simulation method (second embodiment)]
In the simulation method of the embodiment so far, the temperature of the tire model is calculated based on the calorific value of the tire model 13, but the present invention is not limited to such an embodiment. For example, the temperature of the tire model 13 may be calculated in consideration of the temperature distribution of the running tire.

FIG. 7 is a flowchart showing an example of a processing procedure of the simulation method of another embodiment of the present invention. FIG. 8 is a diagram showing an example of the temperature distribution of the tire. In this embodiment, the same configurations as those in the previous embodiments are designated by the same reference numerals, and the description thereof may be omitted.

In the simulation method of this embodiment, the temperature distribution of the running tire is input to the computer prior to the simulation step S2 (step S6). The step S6 of this embodiment is executed prior to the step S1 for inputting the tire model 13 and the road surface model 14, but may be executed after the step S1.

The temperature distribution of the running tire can be obtained as appropriate. In the present embodiment, the temperature of the tire (including the temperature of the contact portion) when the tire is run on the road surface can be obtained by measuring it based on a temperature sensor or the like.

The running conditions of the tire for obtaining the temperature distribution are set to be the same as the running conditions of the tire model 13 in the simulation step S2 (for example, internal pressure condition, load condition L, running speed V3 (shown in FIG. 3), etc.). Is desirable. As a result, the temperature of the tire model 13 can be predicted with high accuracy.

Further, in this embodiment, the temperature distribution when the tire is driven to a state where the temperature does not change (equilibrium state) may be obtained, or a plurality of temperature distributions that change from moment to moment may be acquired. .. The temperature distribution is input to the temperature distribution input unit (not shown) of the data unit 5 shown in FIG.

In the simulation step S2 of this embodiment, in the second step S22 and the fourth step S24 shown in FIG. 5, each element F (i) of the tire model 13 is taken into consideration in consideration of the tire temperature distribution (shown in FIG. 8). The temperature of is calculated. In the present embodiment, the temperature of each element F (i) is obtained by associating the position (coordinate value) of each element F (i) with the position (coordinate value) of the tire in the temperature distribution. Then, in the third step S23, a new friction coefficient of each element F (i) is obtained based on the obtained physical quantity including the temperature of each element F (i) and the friction coefficient table (shown in FIG. 6). Desired.

In the simulation method of this embodiment, the temperature distribution of the running tire (shown in FIG. 8) is used, so that each element F (i) of the tire model 13 is calculated even if the calorific value of the tire model 13 is not calculated. ) Can be obtained. Therefore, in the simulation method of this embodiment, it is possible to shorten the calculation time while maintaining the calculation accuracy of the running state of the tire.

Although the particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments.

Based on the processing procedure shown in FIG. 2, the physical quantity of the running tire model was calculated (Examples 1 and 2). In Examples 1 and 2, the physical quantity (front-rear force) of the running tire model was calculated while changing the coefficient of friction based on the processing procedure shown in FIG.

In Examples 1 and 2, the coefficient of friction was changed based on the contact pressure at the contact, the slip speed at the contact, and the temperature of the tire model. The temperature of the tire model of the first embodiment was set to a predetermined temperature without considering the calorific value of the tire model. On the other hand, the temperature of the tire model of Example 2 was calculated in consideration of the calorific value of the tire model.

For comparison, the physical quantity (front-rear force) of the running tire model was calculated based on a predetermined friction coefficient without changing the friction coefficient (comparative example). The running conditions of the comparative example are the same as those of the first and second embodiments.

The physical quantities (front-rear force) when the actual tires were run on the road surface were measured under the same running conditions as those of Examples 1 and 2 and Comparative Example (Experimental Example). Then, the physical quantities of the experimental examples and the physical quantities of Examples 1 and 2 and the comparative examples were compared. The common specifications are as follows.
Tire size: 195 / 65R15 91H
Rim size: 15 x 6J
Internal pressure condition: 230kPa
Load condition: 4.24kN
Physical quantity; Front-back axial force test results are shown in Table 1.

In Table 1, the physical quantities (front-back force) of Examples 1 and 2 and the comparative example are shown by an index with the physical quantity (front-back force) of the experimental example as 100. The closer the index is to 100, the higher the accuracy of the tire running condition is calculated.

As a result of the test, Examples 1 and 2 in which the friction coefficient was changed could be approximated to the physical quantity of the experimental example as compared with the comparative example in which the friction coefficient was not changed, and the running state of the tire could be calculated with high accuracy. Further, Example 2 in which the calorific value of the tire model is taken into consideration can be approximated to the physical quantity of the experimental example as compared with Example 1 in which the calorific value of the tire model is not taken into consideration, and the running state of the tire can be made more accurate. I was able to calculate with.

S21 1st process S22 2nd process S23 3rd process S24 4th process

Claims (8)

It ’s a tire simulation method.
A process of inputting a tire and a road surface into a computer as a tire model and a road surface model modeled by a finite number of elements, respectively.
The computer includes a simulation step of running the tire model on the road surface model.
The simulation step includes a first step of defining an initial coefficient of friction at a contact portion between the tire model and the road surface model.
A second step of calculating a plurality of physical quantities of the tire model in motion using the initial coefficient of friction, and
A third step of changing the initial coefficient of friction based on at least one of the plurality of physical quantities calculated in the second step, and
A fourth step of calculating the plurality of physical quantities of the running tire model using the changed coefficient of friction.
Tire simulation method. The tire simulation method according to claim 1, wherein the third step and the fourth step are repeated every minute time. The plurality of physical quantities include at least one of the contact pressure at the contact portion, the slip speed at the contact portion, and the temperature of the tire model.
The tire simulation method according to claim 1 or 2, wherein the third step changes the initial coefficient of friction based on at least one of the contact pressure, the slip speed, and the temperature. The tire simulation method according to claim 3, wherein the third step changes the initial friction coefficient based on at least two of the contact pressure, the slip speed, and the temperature. The plurality of physical quantities further include the calorific value of the tire model.
The tire simulation method according to claim 3 or 4, wherein the temperature is calculated in consideration of the calorific value. Prior to the simulation step, the step of inputting the temperature distribution of the running tire into the computer is further included.
The tire simulation method according to claim 3 or 4, wherein the temperature is obtained in consideration of the temperature distribution. The tire simulation method according to any one of claims 1 to 6, wherein the plurality of physical quantities further include at least one of a front-rear force and a lateral force of the tire model. It is a device equipped with an arithmetic processing unit for executing tire simulation.
The arithmetic processing unit is
A model setting unit that sets the tire and the road surface as a tire model and a road surface model modeled by a finite number of elements, respectively.
A simulation calculation unit for running the tire model on the road surface model is included.
The simulation calculation unit
A first calculation unit that defines an initial coefficient of friction at a contact portion between the tire model and the road surface model, and a first calculation unit.
A second calculation unit that calculates a plurality of physical quantities of the tire model in motion using the initial friction coefficient, and
A third calculation unit that changes the initial coefficient of friction based on at least one of the plurality of physical quantities calculated by the second calculation unit.
Includes a fourth calculation unit that calculates the plurality of physical quantities of the tire model in motion using the changed coefficient of friction.
Tire simulation device.

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