JP5466049B2 - Tire performance prediction method and tire performance prediction apparatus - Google Patents

Description

  A tire performance prediction method for predicting tire performance by rolling a tire model obtained by modeling a pneumatic tire with a plurality of elements in contact with a road surface model with a plurality of elements modeled, and a tire performance prediction method The present invention relates to a tire performance prediction apparatus to be executed.

  In recent years, in the development of pneumatic tires, due to the development of numerical analysis methods such as the finite element method and computer environment, pneumatic tires were actually manufactured and newly designed without being mounted on automobiles and running tests It has become possible to predict and evaluate tire performance such as running performance and characteristics of pneumatic tires (see, for example, Patent Document 1). By using the tire performance prediction method and replacing part of the development cycle, such as the design, manufacture, and evaluation of pneumatic tires, with numerical analysis, the development period of pneumatic tires has been shortened.

Japanese Patent No. 3133738 Fig. 2

  However, the conventional tire performance prediction method has the following problems. That is, in the conventional tire performance prediction method, for example, when predicting wet braking performance on a paved road surface, a water film that has entered fine irregularities on the road surface and a narrow groove formed in a tread pattern of a pneumatic tire. The behavior of water flowing through a minute gap formed between the road and the minute unevenness of the road surface was not considered. For this reason, the conventional tire performance prediction method cannot correctly evaluate the tire performance of a pneumatic tire having a complicated tread pattern.

  Therefore, an object of the present invention is to provide a tire performance prediction method capable of accurately predicting the tire performance of a pneumatic tire having a newly designed tread pattern, and a tire performance prediction device that executes the tire performance prediction method.

  In order to solve the above-described problems, the present invention has the following features. That is, the first feature of the present invention is that at least a tire model in which the shape, structure, and material of a pneumatic tire are divided into a finite number of elements, and grooves and land portions formed in the tread portion of the pneumatic tire. The tire model setting step for setting a tread pattern model divided into a finite number of elements, the road surface model setting step for setting a road surface model in which a smooth road surface is divided into finite elements, and the tire model setting step are set. A rolling calculation step for performing rolling calculation for rolling the tread pattern model on the road surface model under a preset initial boundary condition, and a deformation trajectory of the tread pattern model from the calculation result of the rolling calculation step A deformation calculation step for calculating the unit block and a unit block model in which a narrow groove is formed in the unit block of the land portion are set. A unit block model setting step, a partial block model setting step for setting a partial block model formed by collecting a plurality of the unit blocks, and at least an area of the road surface model corresponding to the partial block model. A road surface undulation model setting step for setting a road surface undulation model in which a road surface including undulations smaller than the width is divided into finite elements, and a fluid film on the road surface undulation model set in the road surface undulation model setting step A fluid model setting step for setting a fluid model divided into individual elements, and a boundary condition for setting boundary conditions for the fluid model and the road surface undulation model based on the deformation trajectory of the tread pattern model calculated in the deformation calculation step A setting step and the fluid model in which the boundary condition is set A partial block model rolling calculation step for executing a partial block model rolling calculation for rolling the partial block model on a road surface undulation model, and the partial block from the calculation result of the partial block model rolling calculation step A tire performance prediction method comprising: a partial block model deformation calculation step for calculating a deformation trajectory of a model; and a physical quantity calculation step for obtaining a physical quantity generated in the partial block model or the fluid model calculated in the partial block model deformation calculation step. It is a summary.

  According to the present invention, a finite number of partial block models formed by collecting a plurality of unit block models each having a narrow groove and a road surface including undulations smaller than the width of the narrow groove in an area corresponding to the partial block model. In order to calculate the physical quantity change between the partial block model, the fluid model, and the road undulation model, the tire performance of the pneumatic tire having a fine tread pattern including narrow grooves is set. Predict accurately.

  Further, according to the present invention, when the design of the tread pattern, particularly the narrow groove, is changed, if the basic tire model is the same, only the calculation of the tread pattern model (that is, L analysis) is performed again. Just do it. Therefore, there is an advantage that man-hours for design change and evaluation can be shortened.

  The second feature of the present invention relates to the first feature of the present invention, and is summarized in that, in the road surface model setting step, a friction coefficient on a road surface wetted on the road surface model which is the smooth road surface is set.

  A third feature of the present invention relates to the first or second feature of the present invention, wherein the partial block model is formed by arranging a plurality of the unit blocks in a tread width direction and a circumferential direction of the tire. It is a summary.

  A fourth feature of the present invention is according to any one of the first to third features of the present invention, wherein the road surface undulation among the unit blocks constituting the partial block model that rolls on the road surface undulation model. The gist is that the narrow groove is set only in a unit block in which the normal of the contact surface with the model matches the normal of the road surface model.

  ADVANTAGE OF THE INVENTION According to this invention, the tire performance prediction method and tire performance prediction apparatus which can predict the tire performance of the pneumatic tire which has a newly designed tread pattern accurately can be provided.

FIG. 1 is a flowchart illustrating a tire performance prediction method according to an embodiment of the present invention. FIG. 2A is a plan view illustrating a tire cross-section model set in the tire performance prediction method according to the present embodiment, and FIG. 2B is a view of a tire in which the tire cross-section model is developed in the tire circumferential direction. It is a perspective view explaining a three-dimensional model. FIG. 3 is a perspective view illustrating a tread pattern model. FIG. 4 is a schematic diagram for explaining that the tread pattern model set on a part of the surface of the tire model changes due to rolling of the tire model. FIG. 5 is a perspective view of the unit block model. FIG. 6 is a plan view for explaining a partial block model including a plurality of unit block models. FIG. 7 is an enlarged view showing the road surface undulation model 200. FIG. 8 is a diagram illustrating images of the partial block model 32, the fluid model 50, and the road undulation model 200 set by the tire performance prediction method according to the present embodiment. FIG. 9 is a configuration diagram of a tire performance prediction apparatus that executes the tire performance prediction method according to the embodiment of the present invention.

  An embodiment of a tire performance prediction method according to the present invention will be described with reference to the drawings. Specifically, (1) global local analysis (GL analysis), (2) tire performance prediction device, (3) operation and effect, and (4) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

(1) Global local analysis (GL analysis)
In the present embodiment, GL analysis (Global-Local Analysis) that combines global analysis (Global Analysis: hereinafter referred to as G analysis) and local analysis (Local Analysis: hereinafter referred to as L analysis) is used. The present applicant has already proposed a technique (Japanese Patent No. 313338) related to a tire performance prediction method. Since the details of the GL analysis are disclosed in the above publication, the features of the present invention will be described in detail below.

  FIG. 1 is a flowchart for explaining a tire performance prediction method according to the present embodiment.

  In step S1, a new pneumatic tire to be evaluated by the tire performance prediction method is designed. Specifically, the tire size, shape, structure, material, tread pattern and the like of the pneumatic tire are determined. In steps S11 to S16 described later, G analysis of the pneumatic tire designed in step S1 is executed.

  As step S11, a tire model setting step is executed. Step S11 sets a tire model in which at least the shape, structure, and material of the pneumatic tire are divided into finite elements, and the basic structure of the grooves and land portions formed in the tread portion of the pneumatic tire is finite. Set the tread pattern model divided into elements. Here, the elements of the tread pattern model are preferably set smaller than the elements constituting the tire model.

  Specifically, in step S11, a model for numerical analysis (referred to as a tire model) is created based on a newly designed pneumatic tire. In this embodiment, a finite element method (FEM) is applied as a numerical analysis method for creating a tire model. The tire model is obtained by digitizing an actual pneumatic tire into a data format that can be input to a computer program created based on numerical and analytical methods.

  The tire model created in step S11 is divided into a plurality of elements by element division (for example, mesh division) corresponding to the finite element method (FEM). The element division refers to dividing a pneumatic tire, a road surface, a fluid, and the like into a finite number of small parts (referred to as elements). That is, the tire model is composed of a plurality of elements. In the finite element method, for example, calculation of physical quantities such as deformation, heat, viscoelasticity, etc. is individually calculated for all elements constituting the pneumatic tire, and then the calculation results for all the elements are integrated to calculate the whole tire model. This is a method of calculating a physical quantity.

  FIG. 2 is a diagram for explaining a tire cross-section model 10 and a three-dimensional model (smooth tire model 20) to be described next. In step S11, first, a model of a tire radial direction and tread width direction cross section (referred to as a tire cross section model) is created (see FIG. 2A). The tire cross-section model 10 is created based on data collected from a design drawing, for example. Alternatively, the outer shape of the pneumatic tire is created based on data collected by measuring with a laser shape measuring instrument or the like. In addition, data collected from design drawings about the structure inside the tire in a tire model such as a reinforcing material in which a reinforcing cord made of rubber, belt, ply, iron / organic fiber, etc. in a tire cross section is bundled in a sheet shape, or Based on data collected from actual tires, modeling is performed according to the modeling method of the finite element method.

  Subsequently, a three-dimensional (3D) model 20 of a tire is created by developing the tire cross-section model 10 by one turn in the tire circumferential direction (see FIG. 2B). In step S11, not all the newly designed tread patterns are modeled. The three-dimensional model is a smooth tire model 20 in which the entire tire circumference is set to be smooth. The model set in the G analysis is a model in which a smooth tire model 20 is provided with a belt model 21 and a tread pattern model 22 (see FIG. 3) in which only the basic structure of the groove and land is set. A model of a complete tire including a tread pattern is referred to as a complete tire model and is distinguished from a tire model.

  Next, in step S12, a road surface model setting step is executed. In the road surface model setting step, a road surface model is set in which a smooth road surface having a smooth entire surface is divided into a finite number of elements. In the road surface model setting step, it is possible to set a friction coefficient on a wet road surface to a smooth road surface model that is a smooth road surface. An example of the friction coefficient on a wet road surface is μ = 0.3 to 1.0. More preferably, μ = 0.5 to 0.8.

  In the next step S13, boundary conditions are set. The boundary conditions are various conditions given to the tire model when simulating the behavior of the tire model.

  In step S14, a rolling calculation step is executed. In the rolling calculation step, rolling calculation is performed in which the tread pattern model 22 set in the tire model setting step rolls on a smooth road surface model under preset initial boundary conditions. For example, in the rolling calculation step, a rolling calculation is performed in which the tire model rolls in a state where internal pressure is applied to the tire model, and at least one of rotational displacement and linear displacement is applied to the tire model and a predetermined load is applied. Run. The rolling calculation executed in the rolling calculation step includes rolling conditions during braking.

  In step S15, the calculation result is output as the prediction result of the tire model on the smooth road surface model. The evaluation of the prediction result uses the output value of the prediction result and the distribution of the output value, and numerically expresses how much the predetermined allowable value and allowable characteristics fit each output value and the distribution of the output value. Can be determined by.

  In step S16, a deformation calculation step is executed. In the deformation calculation step, the tread pattern model 22 (see FIG. 3) set as a part of the outermost layer of the tire model at the time of rolling the tire is stepped on the smooth road surface model based on the calculation result in the rolling calculation step. The deformation trajectory until it is put out is calculated (see FIG. 4).

  FIG. 3 is a perspective view for explaining the tread pattern model 22. FIG. 4 is a schematic diagram for explaining that the tread pattern model 22 set on a part of the surface of the tire model changes due to rolling of the tire model. As shown in FIG. 4, in the space S in which the smooth road surface model G is set, the trajectory of L1, L2,... L13 is drawn by calculation as time passes while the tread pattern model 22 is deformed. It is done. The subsequent L analysis is performed based on the obtained deformation trajectory of the tread pattern model 22. In the L analysis, a physical quantity change of a model in which a specific design value is introduced into a part of the tread pattern model is obtained.

  In FIG. 1, the processing from step S21 to step S27 corresponds to L analysis.

  In step S21, a unit block model setting step is executed. The unit block model setting step sets the unit block model 31 in which the narrow grooves 41 to 45 are formed in one block (referred to as a unit block) among the land blocks constituting the tread pattern model. FIG. 5 is a side view of the unit block model as seen from the tire tread width direction. In the present embodiment, the narrow groove is a groove having a groove width of about 0.3 mm to 4 mm as an example. Such a groove is closed by the ground pressure when grounded.

  In step S22, a partial block model setting step is executed. In the partial block model setting step, a partial block model 32 formed by collecting a plurality of unit blocks is set.

  FIG. 6 is a plan view for explaining the partial block model 32. The partial block model 32 is formed by arranging a plurality of unit block models 31 in the tire tread width direction TW and the circumferential direction TR.

  In the unit block model setting step, the normal of the contact surface when the partial block model 32 and the road surface undulation model contact each other is the normal of the road surface model (in the case of the road surface undulation model, the normal of the surface obtained by averaging the undulations) Narrow grooves may be set only in the reference unit block model that matches, and the other unit blocks may be treated as blocks without a narrow groove. Here, in the partial block model shown in FIG. 6, the reference unit block model refers to a unit block model that is arranged on the tire equator line CL and arranged in the center in the tire width direction (in FIG. 6, Unit block model 31C).

  In step S23-1, a road surface undulation model setting step is executed. The road surface undulation model setting step sets a road surface undulation model in which a road surface including undulations smaller than the width of the narrow groove is divided into a finite number of elements in an area corresponding to at least a partial block model of the smooth road surface model.

  FIG. 7 is an enlarged view showing the road surface undulation model 200. Here, the actual road surface undulation is created based on data collected by measurement with a laser shape measuring instrument or the like. For example, the road surface collected by measurement is modeled by an assembly of elements of a predetermined size (200a, 200b, 200c... Shown in FIG. 7).

  In addition, the one side of each element of the road surface undulation model 200 can be set to about 0.3 mm to 4 mm as an example in consideration of the groove width of the narrow groove. The road surface undulation model 200 is determined by the dimensions of the narrow grooves.

  In step S23-2, a fluid model setting step is executed. The fluid model setting step sets a fluid model obtained by dividing a fluid film (water film) into a finite number of elements on the road surface undulation model set in the road surface undulation model setting step.

  FIG. 8 is a diagram illustrating images of the partial block model 32, the fluid model 50, and the road undulation model 200 set by the tire performance prediction method according to the present embodiment. It is possible to calculate a physical quantity change among the three-party models of the partial block model 32, the fluid model 50, and the road surface undulation model 200 set by the road surface undulation model setting step and the fluid model setting step.

  The road surface undulation model setting step and the fluid model setting step are in accordance with the method disclosed in Japanese Patent Application Laid-Open No. 2006-199217. That is, a road surface including undulations is set by a finite element method, and a water film is set on the road surface.

  In step S24, a boundary condition setting step is executed. The boundary condition setting step sets a boundary condition for the road surface undulation model based on the deformation trajectory of the tread pattern model calculated in the deformation calculation step.

  In step S25, a partial block model rolling calculation step is executed. The partial block model rolling calculation step executes the partial block model rolling calculation for rolling the partial block model on the fluid model and road surface undulation model for which boundary conditions are set.

  In step S26, a partial block model deformation calculation step for calculating the deformation trajectory of the partial block model from the calculation result of the partial block model rolling calculation step is executed, and the result is output. In addition, a physical quantity calculation step and a prediction step are executed. In the physical quantity calculation step, a physical quantity generated in the partial block model calculated in the partial block model deformation calculation step is calculated. Further, the physical quantity generated in the fluid model calculated in the partial block model deformation calculation step is calculated.

  In the prediction step, the tire performance of the complete tire model corresponding to the entire pneumatic tire in which the partial block model is formed over the entire circumference of the tread portion is predicted based on the calculated physical quantity.

  In step S27, the prediction result is evaluated.

  In step S28, it is determined from the evaluation of the prediction result whether the prediction performance is good. In step S28, an allowable range is predetermined for the evaluation value, and when the evaluation value of the prediction result is within the allowable range, it is determined that the prediction performance is good. For example, the operator may input the quality of the prediction result from an input unit such as a keyboard.

  As a result of the evaluation of the predicted performance, if the target performance is insufficient, the result is negative in step S29. In step S29, the design plan is changed or corrected, and the L analysis is performed again. If the performance is sufficient, the result is affirmative in step S28, and in step S30, the tire of the design plan set in step S1 or the design plan modified in step S29 is adopted as a good performance, and this routine is terminated.

(2) Tire Performance Prediction Device FIG. 9 shows an outline of a computer 300 as a tire performance prediction device that executes a tire performance prediction method according to an embodiment of the present invention. As shown in FIG. 9, the computer 300 includes a main body 310 including a storage unit (not shown) such as a semiconductor memory and a hard disk, a processing unit (not shown), an input unit 320, and a display unit 330. . The processing unit executes the tire performance prediction method described with reference to FIG.

  The computer 300 may be provided with a removable storage medium (not shown) and a driver capable of writing / reading the storage medium. A program for executing the tire performance prediction method described with reference to FIG. 1 may be recorded in a storage medium in advance, and the program read from the storage medium may be executed. The program may be stored (installed) in the storage unit of the computer 300 and executed. Although not shown, the computer 300 may be connectable to a network, for example. You may acquire the program which performs a tire performance prediction method via a network.

(3) Action / Effect According to the tire performance prediction method according to the embodiment of the present invention, the partial block model 32 formed by a plurality of unit block models 31 formed with the narrow grooves 41 to 45, and the partial block By setting a road surface undulation model including undulations smaller than the width of the narrow grooves 41 to 45 in the region corresponding to the model 32, and calculating physical quantity changes between the partial block model 32, the fluid model and the road surface undulation model, The tire performance of a pneumatic tire having a fine tread pattern including the narrow grooves 41 to 45 can be accurately predicted.

  In the tire performance prediction method according to this embodiment, a model in which a plurality of unit block models 31 are arranged in the tire tread width direction TW and the circumferential direction TR is referred to as a partial block model 32. That is, by creating the partial block model 32 using the unit block model 31 as a repeating unit, the number of steps for creating the partial block model 32 can be reduced.

  Further, by creating the partial block model 32 using the unit block model 31 as a repeating unit, the influence of the adjacent unit block model 31 on the drainage performance can be calculated, and the prediction accuracy of the drainage performance is improved.

  Furthermore, in the tire performance prediction method according to this embodiment, in the unit block model setting step, the normal of the contact surface when the partial block model 32 and the road surface undulation model contact each other is the normal of the road surface model (the road surface undulation model). If there is a narrow groove only in the reference unit block model that matches the normal of the surface where the undulations are averaged), and other unit blocks are treated as blocks without a narrow groove, the amount of computation is greatly increased. Can be reduced. By defining a narrow groove only at least in the reference unit block, the amount of calculation for L analysis can be reduced.

(4) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments and examples will be apparent to those skilled in the art. For example, the embodiment of the present invention can be modified as follows.

  In the tire performance prediction method according to the present embodiment, the case where the finite element method is used as the numerical analysis method has been described. However, a difference method or a finite volume method can also be used.

  In the tire performance prediction method according to the present embodiment, in the tire model setting step of G analysis, the tire model is formed in the tire model in which the shape, structure, and material of the pneumatic tire are divided into finite elements, and the tread portion of the pneumatic tire. It was explained that the tread pattern model was set by dividing the basic structure of the groove and land part into finite elements. However, in the G analysis, a smooth tire model may be used, and the structure of the groove including the narrow groove formed in the tread portion and the land portion may be set by the L analysis.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

The time until the completion of prediction was compared between the simulation according to the present embodiment and the simulation according to the conventional method. As a sample pneumatic tire, a tire having a groove, a land portion, and a narrow groove formed in the land portion was used. This pneumatic tire is stipulated in “The Tire and Rim Association Inc. Year Book” in the United States, “The European Tire and Rim Technical Organization Standards Manual” in Europe, and “JATMA Year Book” of the Japan Automobile Tire Association in Japan. Standard braking load, standard internal pressure, standard rim, and driving performance on a wet road at a speed of 60km / h to predict braking performance when suddenly stopped with full braking. Compared. The simulation according to the conventional method is a method for calculating a rolling motion of a complete tire model.

  In the simulation according to the present embodiment, when the time index for G analysis is 100, the L analysis index is 284. In the conventional method, it was 1822.

  From the results shown in Table 1, in the simulation according to the present embodiment, a total calculation time of G analysis and L analysis (384) is required. For example, when the design of a tread pattern including a narrow groove is changed Therefore, only the L analysis needs to be executed, and the index of time related to the second and subsequent recalculations associated with the design change is 284. The conventional method requires 1822 every time the design is changed. Therefore, in the simulation according to the present embodiment, it can be understood that the calculation can be performed more efficiently as the design plan of the tread pattern to be calculated increases. By utilizing this, the tire development cycle can be accelerated.

  DESCRIPTION OF SYMBOLS 10 ... Tire cross-section model, 20 ... Smooth tire model, 21 ... Belt model, 22 ... Tread pattern model, 31 ... Unit block model, 31C ... Reference unit block model, 32 ... Partial block model, 41-45 ... Narrow groove, 50 ... fluid model, 200 ... road surface undulation model, 300 ... computer, 310 ... main body, 320 ... input unit, 330 ... display unit

Claims (6)

A tire that is modeled and calculated by a computer, and that predicts tire performance by rolling a tire model in which a pneumatic tire is modeled with multiple elements in contact with a road surface model that is modeled with multiple elements on the road surface A performance prediction method,
A tire model in which at least the shape, structure and material of the pneumatic tire are divided into finite elements, and a tread in which the basic structure of the groove and land formed in the tread portion of the pneumatic tire is divided into finite elements A tire model setting step for setting a pattern model;
A road surface model setting step for setting a road surface model obtained by dividing a smooth road surface into a finite number of elements;
A rolling calculation step for executing a rolling calculation for rolling the tread pattern model set by the tire model setting step on the road surface model under a preset initial boundary condition;
A deformation calculation step of calculating a deformation trajectory of the tread pattern model from the calculation result of the rolling calculation step;
A unit block model setting step for setting a unit block model in which a narrow groove is formed in the unit block of the land portion;
A partial block model setting step for setting a partial block model formed by collecting a plurality of the unit blocks;
A road surface undulation model setting step for setting a road surface undulation model in which a road surface including undulations smaller than the width of the narrow groove is divided into a finite number of elements in an area corresponding to at least the partial block model of the road surface model;
A fluid model setting step of setting a fluid model obtained by dividing a fluid film into a finite number of elements on the road surface undulation model set in the road surface undulation model setting step;
A boundary condition setting step for setting boundary conditions in the fluid model and the road surface undulation model based on the deformation trajectory of the tread pattern model calculated in the deformation calculation step;
A partial block model rolling calculation step for executing a partial block model rolling calculation for rolling the partial block model on the fluid model and road surface undulation model in which the boundary conditions are set;
A partial block model deformation calculation step of calculating a deformation locus of the partial block model from a calculation result of the partial block model rolling calculation step;
A tire performance prediction method comprising: a physical quantity calculation step for obtaining a physical quantity generated in the partial block model or the fluid model calculated in the partial block model deformation calculation step. The tire performance prediction method according to claim 1, wherein, in the road surface model setting step, a friction coefficient on a road surface wetted by the road surface model which is the smooth road surface is set to 0.3 to 1.0 .   The tire performance prediction method according to claim 1 or 2, wherein in the road surface undulation model setting step, one side of each element of the road surface undulation model is set to 0.3 mm to 4 mm. The tire performance prediction method according to any one of claims 1 to 3, wherein the partial block model is formed by arranging a plurality of the unit blocks in a tread width direction and a circumferential direction of the tire. Of the unit blocks constituting the partial block model that is allowed to roll on the road surface undulation model, only the unit block whose normal to the contact surface with the road surface undulation model coincides with the normal of the road surface model is the narrow groove. The tire performance prediction method according to any one of claims 1 to 4 , wherein: A tire performance prediction apparatus that executes the tire performance prediction method according to any one of claims 1 to 5 .

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