JP4525263B2 - Physical quantity acquisition method in tire contact state - Google Patents

Description

The present invention relates to a physical quantity acquisition how the tire contact state to obtain a physical quantity of the ground state of the tire.

  A tread pattern is formed on the tread portion of the tire. This tread pattern is composed of land portions defined by a plurality of groove portions, that is, a plurality of blocks and / or ribs (hereinafter simply referred to as “blocks / ribs”). The ground contact state of the tire (the state where the tire is in contact with the road surface) affects various performances of the tire. Among them, handling stability, noise performance, wear characteristics, etc. are influenced by the rigidity of the block / rib group composed of a plurality of blocks / ribs existing on the contact surface with the road surface of the tire, that is, the pattern rigidity. Therefore, in order to improve these performances, it is important to accurately predict the pattern rigidity.

  Conventionally, as a method of predicting the pattern rigidity, the rigidity of the block / rib unit 100 is calculated by a linear theory using the sectional moment of the block / rib unit to which an external force is applied, and the calculated block / rib unit is calculated. There is a method of predicting based on 100 stiffness. FIG. 7A is a schematic diagram of bending deformation of the block / rib alone. FIG. 7-2 is a schematic diagram of shear deformation of a block / rib alone. Here, the transverse elastic constant C, which is an index of the rigidity of the block / rib unit 100, can be calculated by taking into account bending deformation and shear deformation of the block / rib unit 100.

Specifically, first, a deformation amount w ₁ due to bending is obtained from the following equation (1). As shown in FIG. 7A, P is an external force applied to the block / rib unit 100, l is a distance from a fixed surface that fixes one end of the block / rib unit 100, E is Young's modulus, and I is a cross section. Second moment.
w ₁ = (Pl ³ ) / (3EI) (1)

Next, the deformation amount w ₂ due to shear is obtained from the following equation (2). As shown in FIG. 7-2, A is the cross-sectional area of the block / rib unit 100, and G is the shear modulus.
w ₂ = (Pl) / (AG) (2)

The lateral elastic constant C is approximately calculated from the sum w of the deformation amount w ₁ by bending and the deformation amount w ₂ by bending obtained from the above equation (1) and the external force P applied to the block / rib unit 100. It can obtain | require by following formula (3). Here, in consideration of the incompressibility of rubber, G = E / 3.
C = P / w = P / (w ₁ + w ₂ ) = E / ((l ³ / 3I) + (3 l / A)) (3)

  The transverse elastic constant C of the block / rib unit 100 calculated by the above formula (3) is dominated by the change in the cross-sectional area A of the block / rib unit 100 when the sectional moment I of the block / rib unit 100 is large. Is done. That is, when the cross-sectional secondary moment I of the block / rib unit 100 increases, the influence of the cross-sectional secondary moment I on the transverse elastic constant C of the block / rib unit 100 decreases. Further, the cross-sectional area A does not include the shape effect of the block / rib unit 100, and does not take into account the influence of geometric nonlinearity. Therefore, it is difficult to accurately calculate the rigidity, which is a physical quantity generated in the block / rib unit 100 to which the external force is applied, and it is difficult to accurately predict the pattern rigidity.

  Therefore, as shown in Patent Document 1, a method of predicting the rigidity of the block / rib unit 100 by dividing the block / rib unit 100 into a finite number of elements has been proposed. According to this, the rigidity of the block / rib unit 100 can be predicted with higher accuracy than the rigidity of the block / rib unit 100 is calculated by the linear theory using the sectional moment of inertia.

International Publication No. 98/29270 Pamphlet

  However, in the method shown in Patent Document 1, the rigidity of each block / rib unit 100 of the block / rib group existing on the ground contact surface of the tire is predicted, and the predicted rigidity of each block / rib unit 100 is estimated. It was necessary to predict the pattern stiffness. That is, there is a problem that it is necessary to predict all the rigidity of the plurality of blocks / ribs 100 existing on the contact surface with the road surface of the tire, and it takes a lot of time to predict the pattern rigidity.

  Note that the force that the tire receives during cornering of the vehicle changes from moment to moment, and this force is applied as a shearing force that is an external force to the block / rib group existing on the ground contact surface of the tire. On the other hand, normal tire tread patterns are composed of blocks / ribs of various shapes, so in most cases the pattern stiffness does not become a constant value depending on the direction of the applied shear force, but is angle dependent. Have Therefore, when predicting the pattern rigidity, it is necessary to consider the angle dependency of the pattern rigidity, and therefore it is also necessary to predict the pattern rigidity for each direction in which a shear force is applied.

  Here, conventionally, prediction of tire performance has been performed by a tire model having only main grooves continuous in the tire circumferential direction or a tire model having no grooves at all. However, with the rapid development of computers, it is now possible to generate a full tire model that combines a tread pattern model model and a tire casing model, and to predict tire performance using this full tire model. became.

  However, in order to predict the pattern stiffness, which is a physical quantity generated in the pattern model included in the full tire model by applying external force to the full tire model, there are many elements that make up the full tire model, so a huge amount of calculation is required. Time is needed. In particular, in order to predict the pattern rigidity for each direction in which a shearing force, which is an external force, is applied in consideration of the angle dependency of the pattern rigidity, there is a problem that a much larger calculation time is required.

The present invention was made in view of the above, Oite the physical quantity acquisition how the tire contact state, thereby improving the prediction accuracy of the physical quantity occurring in the additional pattern model of an external force to obtain the physical quantity and to provide a physical quantity acquisition how in the tire contact state can suppress an increase in the total time for.

In order to solve the above-described problems and achieve the object, the present invention generates a pattern model composed of a finite number of elements based on the procedure for obtaining the tire contact shape and the acquired tire contact shape. A pattern stiffness based on the displacement, reaction force, and reaction force at each node of each element, which is a physical quantity generated in the pattern model to which the external force is applied, and a procedure for adding an external force to the generated pattern model see containing and a procedure for acquiring one of the pattern model, and characterized in that it is generated based on the groove bottom region adjacent to the tread pattern region and the tread pattern region constituting a ground contact shape of the tire To do.

According to the present invention, a model of a block / rib group existing on the contact surface with the road surface of the tire, that is, a pattern model, is generated from the acquired contact shape of the tire. An external force is applied to the generated pattern model, and a physical quantity generated in the pattern model to which the external force is applied, for example, a pattern rigidity that is a rigidity of a block / rib group existing on the contact surface with the road surface of the tire is acquired. Then, for example, an evaluation value in the ground contact state of the tire is acquired based on the acquired pattern rigidity. Therefore, since the physical quantity is predicted based on the pattern model generated from the acquired contact shape with respect to the road surface of the tire, the physical quantity of the block / rib alone calculated by the linear theory using the second moment of section, or the block / rib alone The prediction accuracy is improved compared to the method of predicting the physical quantity of the block / rib group existing on the contact surface with the road surface of the tire based on the physical quantity of the block / rib unit predicted by dividing the block into a finite number of elements can do. In addition, the pattern model is generated based on the acquired block / rib group on the contact surface with the road surface of the tire, and the evaluation is performed only with the pattern model. Therefore, the number of elements is greatly increased compared to the full tire model. Can be reduced. Therefore, the generation time for generating the pattern model can be shorter than the generation time for the full tire model. In addition, the calculation time for acquiring the physical quantity generated in the pattern model is significantly smaller than the full tire model, so external force is applied to the full tire model and the physical quantity generated in the pattern model of this full tire model is acquired. The calculation time can be shorter than the calculation time. By these, it is possible to suppress an increase in the total time for acquiring the physical quantity generated in the pattern model.
Here, the tread portion of the actual tire includes a plurality of blocks / ribs that are tread pattern areas, a groove under rubber that is a groove under area adjacent to the inside in the tire radial direction of the tread pattern area, and the groove under area. It is comprised by fiber reinforcement layers, such as a belt which is a fiber reinforcement layer area | region adjacent to the tire radial direction inner side. Therefore, according to the present invention, the pattern model is generated based on the tread pattern region and the sub-groove region, whereby the deformation state of the block / rib group on the contact surface with the actual road surface of the tire can be approximated. . Thereby, since pattern rigidity is estimated based on the pattern model produced | generated based on a tread pattern area | region and a groove bottom area | region, prediction accuracy can further be improved.

In the present invention, in the physical quantity acquisition method in the tire ground contact state, the external force is a compressive force and a shear force.

Further, in the present invention, the physical quantity acquisition method in the tire ground contact state is characterized in that the physical quantity generated in the pattern model to which the external force is applied is repeatedly acquired by changing the direction in which the shear force is applied.

  According to the present invention, the direction of the shearing force, which is an external force applied to the generated pattern model, is made different, and the pattern stiffness, which is a physical quantity generated in the pattern model, is obtained for each shearing force having a different direction. Therefore, since the physical quantity can be accurately predicted based on the pattern model generated from the acquired contact shape with respect to the road surface of the tire, the prediction accuracy of the physical quantity that changes due to the applied shear force can also be improved. In addition, the calculation time when acquiring a physical quantity that changes due to the applied shear force is significantly smaller than the full tire model in this pattern model, so shear force is applied to the full tire model from different directions, The calculation time required for acquiring the physical quantity generated in the pattern model of the full tire model that changes due to the applied shear force can be made shorter. Thereby, the increase in the total time for acquiring the physical quantity which arises in the pattern model which changes with the added shear force can be suppressed.

According to the present invention, in the physical quantity acquisition method in the tire ground contact state, the finite number of elements constituting the pattern model is at least one of a pentahedral element and a hexahedral element.

  Here, when the pattern model is configured to include tetrahedral elements, the accuracy of predicting the pattern rigidity, which is a physical quantity generated in the pattern model, is reduced by applying an external force. However, according to the present invention, the elements constituting the pattern model are pentahedral elements or hexahedral elements. Thereby, prediction accuracy can further be improved.

Further, in the present invention, in the physical quantity acquisition method in the tire contact state, the pattern model includes a tread pattern region that constitutes a contact shape of the tire, a groove region adjacent to the tread pattern region, and a groove region adjacent to the tread pattern region. It produces | generates based on the fiber reinforcement layer area | region to do.

According to the present invention, the pattern model is generated based on the tread pattern region and other regions (the sub-groove region and the fiber reinforcement layer region), so that the block / rib group on the contact surface with the road surface of the actual tire is generated. The deformation state can be approximated. Thus, preparative red pattern region, the predicted pattern stiffness based on the pattern models generated based on the groove bottom region and the fiber reinforced layer region, it is possible to further improve the prediction accuracy.

Physical quantity acquisition how the tire contact state according to the present invention, because it generates a pattern model from the ground state of the tire, while improving the prediction accuracy of the physical quantity occurring in the pattern model is added an external force, in order to obtain this physical quantity There is an effect that an increase in the total time can be suppressed.

Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following Example. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. Here, in the physical quantity acquisition method in the tire contact state in the following description, an external force, here, a physical quantity generated in a pattern model by adding a compressive force and a shearing force, here, a finite element method (analysis method for predicting pattern stiffness) The case where Finite Element Method (FEM) is used will be described. The analysis method applicable to the tire simulation method according to the present invention is not limited to the finite element method, but also uses a boundary element method (BEM), a finite difference method (FDM), or the like. Can do. Further, a plurality of these analysis methods may be used in combination. Here, the finite element method is an analysis method suitable for structural analysis, and is suitable for structural analysis of tires.

FIG. 1 is a diagram illustrating a configuration example of a tire contact shape evaluation apparatus that executes a physical quantity acquisition method in a tire contact state according to the present invention. As shown in the figure, the tire ground contact shape evaluation apparatus 10 includes a processing unit 11, a storage unit 12, an input port _13IN, and an output port _13OUT . The processing unit 11 and the storage unit 12 are connected to an input port 13 _IN and an output port 13 _OUT , respectively.

The processing unit 11 includes a grounding shape acquisition unit 14, a pattern model generation unit 15, an external force addition unit 16, an analysis unit 17, and a contact state evaluation unit 18. These performs a physical quantity acquisition method in tire contact state to obtain a physical quantity of the ground state of the tire. The ground shape acquisition unit 14, the pattern model generation unit 15, the external force addition unit 16, the analysis unit 17, and the contact state evaluation unit 18 are connected to the input port 13 _IN and the output port 13 _OUT , respectively.

The tire ground contact state evaluation device 10 is connected to a terminal device 20 and various data servers 30. That is, the terminal device 20 and the various data servers 30 are connected to the input port 13 _IN and the output port 13 _OUT , respectively. The terminal device 20 is used to input from the input device 21 connected to the data necessary for the terminal device 20 to perform the physical quantity acquisition method in tire ground state to the tire contact state evaluation device 10. The necessary data includes, for example, physical property values of a land material (rubber) constituting a tread pattern of a tire to be evaluated (not shown), compressive force and shear force which are external forces applied to a pattern model 4 described later. Each is the size and direction. The terminal device 20 receives the evaluation result in the tire ground contact state from the tire ground contact state evaluation device 10 and displays the evaluation result on the display device 22 connected to the terminal device 20. Moreover, when each part 14-18 of the process part 11 performs the physical quantity acquisition method in a tire ground contact state, the various databases stored in the said various data server 30 can be utilized.

The storage unit 12, data physical quantity acquisition computer program in the tire contact state physical quantity acquisition method is incorporated in a tire ground state (hereinafter, referred to as "program") and, later obtained from the various data servers 30 pattern Data such as material properties given to the model 4 is stored. Here, the storage unit 12 is configured by a combination of a memory device such as a RAM and a ROM, a fixed disk device such as a hard disk, a storage means such as a flexible disk and an optical disk, and the like.

The program is not necessarily limited to a single configuration, and functions in cooperation with a program already stored in a computer system, for example, a separate program represented by an OS (Operating System). It may be achieved. Further, the above-described program for realizing the units 14 to 18 of the processing unit 11 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. It may perform a physical quantity acquisition method in Rita bad ground state. The “computer system” includes hardware such as the OS and peripheral devices.

The processing unit 11 includes a memory such as a RAM and a ROM, and a CPU (Central Processing Unit). When executing the physical quantity acquisition method in the tire ground contact state, the processing unit 51 reads the program into a memory (not shown) of the processing unit 11 and performs calculation. Note that the processing unit 11 appropriately stores a numerical value in the middle of the calculation in the storage unit 12 and appropriately takes out the stored numerical value from the storage unit 12 and performs the calculation. The processing unit 11 implements a ground shape acquisition unit 14, a pattern model generation unit 15, an external force addition unit 16, an analysis unit 17, and a contact state evaluation unit 18 by using dedicated hardware instead of the program. It may be.

Next, a description will be given physical quantity acquisition method in tire ground. FIG. 2 is a diagram showing a flowchart of the physical quantity acquisition method in the tire ground contact state according to the present invention. FIG. 3 is a diagram showing the acquired ground contact shape of the tire. FIG. 4A is a diagram illustrating a processing state of the acquired tire ground contact shape. FIG. 4B is a diagram illustrating the generated pattern model and its deformation state.

As shown in FIG. 2, the physical quantity acquisition method in tire ground state, first, the ground contact shape acquiring unit 14 of the processing unit 11 acquires the contact shape of the tire (step ST1). There are various methods for obtaining the ground contact shape 1 of the tire. For example, the tire ground contact shape 1 may be obtained from an actual tire. In this case, first, an imaging device (not shown) images the actual ground contact state of the tire. As for the actual ground contact state of the tire, this actual tire is mounted on a specified rim specified in a standard such as JATMA, filled with air of a specified internal pressure, and made of a tempered glass having transparency, etc. This is achieved by adding a specified load to the shape. Next, light from an illuminating lamp is applied from the back surface of the actual tire support substrate, and an image is picked up by an image pickup device through a sheet-like medium. The imaging device generates image data from the captured ground state of the actual tire. Then, the ground contact shape acquisition unit 14 of the processing unit 11 of the tire ground contact state evaluation device 10 acquires the generated image data as the tire ground contact shape 1 as shown in FIG. The acquired tire ground contact shape is stored in the storage unit 12. The contact shape acquisition unit 14 may acquire the image data generated by the imaging device from the actual tire contact state in a state where the slip angle and the camber angle are given to the actual tire as the tire contact shape 1. good.

  Here, the contact shape 1 of the tire acquired by the contact shape acquisition unit 11 of the processing unit 11 is not limited to that acquired from the actual contact shape of the tire, but approximates the actual contact shape of the tire. It may be. For example, the contact shape acquisition unit 14 estimates the actual tire contact shape based on the tire outer diameter and tire cross-sectional shape of the actual tire stored in the storage unit 12 in advance, and the estimated actual tire The ground contact shape may be acquired as the tire ground contact shape 1. Further, in the contact shape acquisition unit 14, if the actual contact shape of the tire can be approximated to an ellipse that is a geometric shape, the geometric shape may be acquired as the contact shape 1 of the tire. good.

The image data is stored in a storage unit of an imaging device (not shown). Therefore, the image data may be stored in advance in the various data servers 30, and the ground shape acquisition unit 14 may acquire the image data from the various data servers 30. Further, the image data may be stored in advance in a recording medium (not shown), and the ground shape acquisition unit 14 may acquire the image data from the recording medium connected to the terminal device 20. Further, the tire contact shape evaluation device 10 and an imaging device (not shown) are connected in advance, and the contact shape acquisition unit 14 acquires image data via a storage unit, an output port, and an input port 13 _IN of the imaging device (not shown). May be.

  Next, the pattern model generation unit 15 of the processing unit 11 generates a pattern model 4 from the acquired ground contact shape 1 of the tire (step ST2). Specifically, first, the pattern model generation unit 15 recognizes the outline of each block / rib unit 2 in the tire contact shape 1 (image data) acquired by the contact shape acquisition unit 14 as shown in FIG. To do. Next, as shown in FIG. 4A, the area within the outline of each recognized block / rib unit 2 is divided into a finite number of two-dimensional elements 3a. That is, a pneumatic tire for which performance is predicted is divided into two-dimensional elements 3a based on the finite element method, so that a two-dimensional finite element model 3 is generated from the acquired ground contact shape 1 of the tire. Here, examples of the two-dimensional element 3a include a triangular element and a quadrilateral element. Then, as shown in FIG. 4B, the pattern model is obtained by sweeping the two-dimensional finite element model 3 in the thickness direction so as to have the same thickness as that of the actual tire tread rib / block alone. 4 is generated. The method for generating the pattern model 4 is not limited to the above method.

The generated pattern model 4 is composed of a finite number of three-dimensional elements 4a, and a block / rib unit model 5 is formed by a plurality of three-dimensional elements 4a. The three-dimensional element 4a constituting the pattern model 4 includes elements that can be used by a computer, such as a tetrahedral element, a pentahedral element, and a hexahedral element. Here, that were generated pattern model 4, as a three-dimensional element 4a constituting the pattern model 4 for use in the physical quantity acquisition method in tire contact state, constituting a three-dimensional element 4a is pentahedra elements and / or hexahedral elements It is preferable that As a result, a tetrahedral element that causes a decrease in the prediction accuracy of pattern rigidity, which is a physical quantity generated in the pattern model 4, by adding an external force described later to the generated three-dimensional elements of the pattern block 4. Is not included in the three-dimensional element 4a. Thus, the physical quantity acquisition method in tire ground state, predicts the pattern rigidity based on the pattern model 4 that consists of a three-dimensional element 4a, such as five tetrahedral elements and / or hexahedral elements, to improve the prediction accuracy Can do. The generated pattern model 4 includes three-dimensional elements that form the pattern model 4 such as sipes, narrow grooves, raised bottoms of grooves, and notches at the ends of blocks / ribs, which are formed in an actual tire tread pattern. It may be modeled by 4a. Here, the divided three-dimensional elements 4a are identified one by one using three-dimensional coordinates in the process of analysis by the pattern model generation unit 15 of the processing unit 11.

  The pattern model generation unit 15 sets material characteristics of each three-dimensional element 4a of the pattern model 4 before applying an external force described later to the pattern model 4. Here, a physical property value as a linear material may be set for each three-dimensional element 4a that approximates the block / rib group on the contact surface with the actual tire road surface. In order to approximate the rubber which is a material constituting the block / rib group on the ground contact surface, it is preferable to set physical property values as a rubber elastic material which is a non-compressible material as well as a non-linear material. Specifically, by inputting a material characteristic to be set for the pattern model 4 generated from the input device 21, a physical property value corresponding to various material characteristics stored in various data servers 30 is input. The physical property values of the material characteristics are set in each three-dimensional element 4a of the pattern model 4.

  Next, the external force adding unit 16 of the processing unit 11 applies an external force to the pattern model 4 (step ST3). Specifically, as shown in FIG. 4B, a compression force for compressing the pattern model 4 and a shearing force for shearing the pattern model 4 are added to the generated pattern model 4 as external forces. Here, this compressive force is an arbitrary value and is uniformly applied to each node of each three-dimensional element 4a constituting the pattern model 4 in the thickness direction (the direction toward the inner side in the tire radial direction of the actual tire). It is what is done. The external force adding unit 16 acquires pressure distribution data on the contact surface between the actual tire and the road in advance, and applies a compressive force to each node of each three-dimensional element 4a based on the acquired pressure distribution data. You may do it. On the other hand, the shearing force is an arbitrary value, and is added to the entire pattern model 4 in an arbitrary direction orthogonal to the thickness direction of the pattern model 4, that is, uniformly added to each node of each three-dimensional element 4a. . The compressive force and shear force are not limited to being applied as a force to each three-dimensional element 4a of the pattern model 4, and may be applied as a forced displacement. Specifically, for example, among the three-dimensional elements 4a constituting the pattern model 4, for reference to the nodes on the upper surface of the three-dimensional elements 4a constituting the surface of the pattern model 4, or the reference nodes of the nodes on the upper surface Forcible displacement may be added to.

  Next, the analysis unit 17 of the processing unit 11 analyzes the pattern model 4 in a state where the external force is applied, and acquires a physical quantity generated in the pattern model 4 due to the addition of the external force (step ST4). The physical quantity includes displacement and reaction force at each node of each three-dimensional element 4a. Here, pattern rigidity is acquired based on the reaction force. Specifically, for example, a reaction force per unit displacement amount when a node on the upper surface of each three-dimensional element 4a is displaced by adding an external force is calculated, and the sum of the calculated reaction forces is calculated as a pattern stiffness. To do.

  Then, the ground contact state evaluation unit 18 of the processing unit 11 acquires an evaluation value based on the pattern rigidity which is the acquired physical quantity, and based on the evaluation value, the tire ground contact state (the tire is in contact with the road surface). (State) is predicted and evaluated (step ST5). Here, the performance of the tire in the ground contact state includes, for example, steering stability, noise performance, wear characteristics, and the like.

Thus, to end the tires of the simulation method. The physical quantity acquisition method in tire contact state, acquired since predicting a physical quantity based on the pattern model 4 generated from the ground shape 1 of the tire, calculated block / rib itself by linear theory using second moment Predicting the physical quantity of a block / rib group existing on the contact surface with the road surface of the tire based on the physical quantity of the block or rib and dividing the block / rib simple substance into a finite number of elements. In comparison, the prediction accuracy can be improved. In addition, the pattern model 4 is generated based on the acquired block / rib group existing on the ground contact surface with the road surface of the tire, and evaluation is performed using only the pattern model 4, so the number of elements is smaller than that of the full tire model. It can be greatly reduced. Therefore, the generation time for generating the pattern model 4 can be shorter than the generation time for the full tire model. Furthermore, since the number of three-dimensional elements 4a constituting the pattern model 4 is significantly smaller than the number of elements of the full tire model, the calculation time when acquiring the physical quantity generated in the pattern model 4 is reduced. In addition, the calculation time for acquiring the physical quantity generated in the pattern model of the full tire model can be made shorter than the calculation time. As a result, it is possible to suppress an increase in the total time for acquiring the physical quantity generated in the pattern model 4.

  Note that the angle dependency of the pattern stiffness is taken into account when predicting the pattern stiffness during cornering of a vehicle equipped with actual tires. Accordingly, the direction in which the shearing force is applied is changed, and the pattern rigidity generated in the pattern model 4 for each direction in which the shearing force is applied is acquired. Specifically, the external force adding unit 16 of the processing unit 11 applies external force to the pattern model 4 in step ST3 and the external force applied to the analyzing unit 17 of the processing unit 11 in step ST4 is applied to the pattern model 4. Obtaining the pattern rigidity that occurs is repeated for each direction in which a shear force is applied (dotted line shown in FIG. 2). Then, in step ST5, the ground contact state evaluation unit 18 of the processing unit 11 acquires an evaluation value based on the pattern rigidity acquired for each direction in which the shearing force is applied, and based on the evaluation value, the ground contact state of the tire is acquired. Predict and evaluate performance in the state.

As described above, the direction of the shear force applied to the generated pattern model 4 is changed, and the physical quantity generated in the pattern model 4 is acquired for each shear force different in the added direction. The physical quantity can be accurately predicted based on the pattern model 4 generated from the ground contact shape 1, and the prediction accuracy of the physical quantity that changes due to the applied shear force can also be improved. In addition, since the total number of the three-dimensional elements 4a constituting the pattern model 4 is less than that of the full tire model, the calculation time for acquiring a physical quantity that changes due to the applied shear force is different from that of the full tire model. The force can be applied, and the calculation time required to acquire the physical quantity generated in the pattern model of the full tire model that changes due to the applied shear force can be made shorter than the calculation time. Thereby, the increase in the total time for acquiring the physical quantity which arises in the pattern model 4 which changes with the added shear force can be suppressed. Specifically, according to the physical quantity acquisition method in tire ground state, generates a full tire model adds an external force to the pattern model of the full tire model, a physical quantity generated pattern model of this added full tire model Can be significantly reduced compared to the total time required to obtain.

  Here, when applying a shearing force in a different direction to the pattern model 4, it is 5 ° to 30 ° with reference to the equator direction (0 °, 180 °) of the pattern model 4 corresponding to the actual tire equator direction. It is preferable to apply a shearing force at intervals within the range. This is because if a shear force is applied to the pattern model 4 at intervals smaller than 5 °, the calculation time for acquiring a physical quantity that changes due to the applied shear force becomes long, and the pattern model at intervals greater than 30 °. This is because if a shearing force is added to 4, the prediction accuracy of a physical quantity that changes due to the applied shearing force may be reduced. In the pattern model 4 generated from the actual tire ground contact shape 1 in which the tread pattern is a point-symmetric or directional pattern, it is preferable to apply a shearing force within a range of 0 ° to 180 °. Moreover, in the pattern model 4 produced | generated from the contact shape 1 of the actual tire whose tread pattern is an asymmetric pattern, it is preferable to add a shear force within the range of 0 degree-360 degrees.

5A and 5B are diagrams showing a comparison between the conventional example and the reference example . In Figure 5-1, the reference example shown in A were obtained by the physical quantity acquisition method in the tire contact state, a pattern stiffness change of pattern models 4 when changing the direction of the shearing force. On the other hand, in the conventional example shown in B, the cross-sectional secondary moment and cross-sectional area of the block / rib alone on the actual contact surface between the tire and the road surface were calculated, and the pattern stiffness was calculated by linear theory using them. Then, the cross-sectional secondary moment when the direction of the shear force is changed is calculated in the same manner, and the pattern stiffness when the direction of the shear force is changed is calculated. In Figure 5-2, the reference example shown in C is a pattern stiffness that occurs in the pattern model 4 that varies by shear force obtained by the physical quantity acquisition method in the tire contact state. On the other hand, in the conventional example shown in D, the rigidity of a block / rib unit having a typical shape of a block / rib group on a contact surface between a conventional actual tire and a road surface is calculated by a finite element method or the like. In FIGS. 5A and 5B, the pattern stiffness at each angle (the angle in the direction in which the shear force is applied to the equator direction) is defined with the pattern stiffness in the equator direction of the actual tire or the stiffness of the block / rib alone as 1. The rigidity or the rigidity of the block / rib alone is indexed.

As shown in FIG. 5A, in the reference example shown in A, when the shear force is applied in a direction substantially perpendicular to the equator direction, the pattern rigidity is the highest as compared with the case where the shear force is applied in the equator direction. Although it decreases, the amount of decrease is not as significant as in the conventional example shown in B. Although it depends on the pattern configuration, there are many cases in which the pattern rigidity does not change extremely depending on the direction in which the shearing force is applied. Therefore, the reference example shown in A has a higher prediction accuracy than the conventional example shown in B. I understand that it is expensive.

As shown in FIG. 5-2, in the reference example shown in C , the pattern rigidity is the highest when shear force is applied in a direction substantially perpendicular to the equator direction compared to the case where shear force is applied in the equator direction. The amount to be reduced is larger than the rigidity of the conventional block / rib alone shown in D.

  In addition, in the said Example, when adding a shear direction to the pattern model 4 from a different direction, the contact shape 1 of the tire which the contact shape acquisition part 14 of the process part 11 acquires is the shear force added to the pattern model 4 It is preferable to acquire according to the direction. Thereby, the pattern model generation unit 15 of the processing unit 11 can generate the pattern model 4 based on the ground contact shape 1 of the tire when the shearing force applied by the external force addition unit 16 is applied to the actual tire. . Thereby, the prediction precision of the physical quantity which changes with the added shear force can be further improved.

In the physical quantity acquisition method in tire ground state, external force applying unit 16 of the processing unit 11 is a compression force and shearing force in the generated pattern model 4 was added as the external force is not limited thereto. For example, a twisting force, that is, a rotational moment, may be added to the pattern model 4 instead of the shearing force. Specifically, the rotational moment about the pattern model 4 in the thickness direction of the pattern model 4 may be added to each three-dimensional element 4a.

  Further, the pattern model generation unit 15 of the processing unit 11 may generate the pattern model 4 in a curved state based on the actual curvature of the tire in the tire circumferential direction and the curvature in the tire width direction.

The physical quantity acquisition pattern model generated by the method 4 in tire ground state, limited to the case which is generated based on only the block / rib group in the ground plane of the road surface of the actual tire as described above is not. FIG. 6A is a diagram illustrating a cross-sectional shape of an actual tire. FIG. 6B is a diagram illustrating another generated pattern model. As shown in FIG. 6A, the tread portion of an actual tire is adjacent to the tread pattern region 41 formed by a plurality of blocks / ribs from the outer side in the tire radial direction toward the inner side. And a fiber reinforcement layer region 43 formed by a fiber reinforcement layer such as a belt adjacent to the groove region 42 and the like. Therefore, when the external force is applied, the block / rib group on the contact surface with the road surface of the actual tire is deformed while being influenced by the fiber reinforcing layer such as the rubber under the groove and the belt of the block / rib group. That is, by generating the pattern model 4 based on the tread pattern region 41 and the other region, the groove region 42 or the groove region 42 and the fiber reinforcing layer region 43, the actual contact surface with the road surface of the tire. It is possible to approximate the deformation state of the block / rib group in FIG.

  Accordingly, as shown in FIG. 6B, not only the tread pattern region model 6 generated from the acquired tire ground contact shape 1 but also the tread pattern region model 6 and the under-groove rubber forming the under-groove rubber region 42. Pattern rigidity is predicted based on a pattern model 4 configured by a sub-groove region model 7 in which the fiber is modeled and a fiber reinforcement layer region model 8 in which a fiber reinforcement layer such as a belt forming the fiber reinforcement layer region 43 is modeled. As a result, the prediction accuracy can be improved.

The physical quantity acquisition method pattern model 4 generated by the tire ground state, finite actual block / rib group is a plurality of block / rib itself that exists in the region corresponding to the ground plane of the road surface of the tire It is not limited to the case where it is generated by dividing it into pieces, and it is generated by dividing the block / rib group existing in the area corresponding to the contact surface with the road surface of the actual tire and its peripheral area into a finite number. May be. When a part of the block / rib unit 2 exists in a region corresponding to the contact surface with the road surface of the actual tire, the block / rib unit 2 generated by applying an external force to the generated pattern model 4 There is a possibility that the accuracy of the rigidity of the part corresponding to a part is lowered and the accuracy of the pattern rigidity is lowered. This is because a part of the block / rib unit 2 existing in the region corresponding to the contact surface with the road surface of the actual tire is integrated with another part of the block / rib unit 2 existing in the peripheral region. Therefore, this other part affects a part of the block / rib single body 2. Therefore, the pattern model 4 is generated by dividing a plurality of blocks / ribs 2 existing in an area corresponding to the contact surface with the road surface of the actual tire and its peripheral area into a finite number of pieces, thereby improving the accuracy of pattern rigidity. The decrease can be suppressed.

  This peripheral region is preferably a region including at least a block / rib unit 2 that partially exists in a region corresponding to a contact surface with the road surface of an actual tire. Specifically, the peripheral region in the tire circumferential direction is a range of 50% of the tire ground contact length that is the length in the tire circumferential direction of the ground contact surface from the actual contact surface with the road surface of the tire in the tire circumferential direction. In the tire width direction, it is within a range of 20% of the tire contact width, which is the length of the contact surface in the tire width direction from the actual contact surface with the road surface of the tire.

As described above, the physical quantity acquisition how the tire contact state according to the present invention is useful in predicting the performance of the ground state of the tire, in particular, the prediction accuracy of the physical quantity occurring in the pattern model is added an external force It is suitable for improving and suppressing the increase in the total time for acquiring this physical quantity.

It is a figure which shows the structural example of the tire ground-contact state evaluation apparatus concerning this invention. It is a figure which shows the flowchart of the physical quantity acquisition method in the tire ground contact state concerning this invention. It is a figure which shows the contact shape of the acquired tire. It is a figure which shows the processing state of the acquired contact shape of the tire. It is a figure which shows the produced | generated pattern model and its deformation | transformation state. It is a figure which shows the comparison with a prior art example and a reference example . It is a figure which shows the comparison with a prior art example and a reference example . It is a figure which shows the cross-sectional shape of an actual tire. It is a figure which shows the other pattern model produced | generated. It is a schematic diagram of the bending deformation of a block / rib simple substance. It is a schematic diagram of the shear deformation of a block / rib simple substance.

DESCRIPTION OF SYMBOLS 1 Tire contact shape 2 Block / rib single-piece 3 Two-dimensional finite element model 4 Pattern model 5 Block / rib single-piece model 6 Tread pattern area model 7 Under groove area model 8 Fiber reinforcement layer area model 10 Tire contact state evaluation apparatus 11 Processing part DESCRIPTION OF SYMBOLS 12 Memory _| storage part 13 _IN input port 13 _OUT output port 14 Ground shape acquisition part 15 Pattern model production | generation part 16 External force addition part 17 Analysis part 18 Contact state evaluation part 20 Terminal device 21 Input device 22 Output device 30 Various data servers 40 Tread part 41 Tread pattern area 42 Under groove area 43 Fiber reinforcement layer area 100 Block / rib alone

Claims (5)

The procedure to get the ground contact shape of the tire,
A procedure for generating a pattern model composed of a finite number of elements based on the ground contact shape of the acquired tire,
A procedure for applying an external force to the generated pattern model;
A procedure for obtaining any of displacement, reaction force, and pattern rigidity based on the reaction force at each node of each element, which is a physical quantity generated in the pattern model to which the external force is added,
Only including,
The physical quantity acquisition method in a tire ground contact state , wherein the pattern model is generated based on a tread pattern region constituting a ground contact shape of the tire and a groove under region adjacent to the tread pattern region . The physical quantity acquisition method according to claim 1, wherein the external force is a compressive force and a shear force. 3. The physical quantity acquisition method in a tire ground contact state according to claim 2, wherein the physical quantity generated in the pattern model to which the external force is applied is repeatedly acquired by changing the direction in which the shear force is applied. The physical quantity acquisition method in a tire ground contact state according to any one of claims 1 to 3, wherein the finite number of elements constituting the pattern model is at least one of a pentahedral element and a hexahedral element. The pattern model, characterized in that it is generated based on the tread pattern area, the fiber reinforced layer region adjacent to the groove bottom region and the groove bottom region adjacent to the tread pattern regions forming the contact shape of the tire The physical quantity acquisition method in the tire ground contact state according to any one of claims 1 to 4.

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