KR100541924B1 - Pneumatic tire designing method - Google Patents

Abstract

Design the best mode of a tire under given conditions when trying to obtain a single performance or a plurality of yield-rate performances. Each block included in the two specified pitch groups in the pitch array is modeled (step 100), and the objective function representing the physical quantity for tire performance evaluation, the constraints for constraining the tire shape, and the design angle, which is the wall angle for determining the block shape, are selected. Determine (step 102). Next, the modified model is determined by changing the design variables by Δr _i (steps 104 to 108), and the sensitivity of the objective function and the constraint are calculated by calculating the target function value and the constraint value of the modified model (step 104-108). 110, 112), predicting the amount of change of the design variable to minimize the difference between the block stiffness, determine the shape correction model, calculate the objective function value and use the value of the design variable, each pitch group in the pitch array constituting the tire The block shape of is determined (steps 114 to 120).

Description

PNEUMATIC TIRE DESIGNING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of designing a pneumatic tire, and in particular, to design a pneumatic tire that can efficiently and easily design the design and development of a tire structure, shape, and the like, which achieves a single objective performance, yield-breaking performance, and the like of a tire. It is about a method.

Conventional tire design method has been made by the rule of thumb by repeated experiments and numerical experiments using a calculator. Therefore, the number of test productions and tests required for development has increased, development costs have increased, and the development period has hardly been shortened.

For example, the crown portion of the tire is designed by several arcs in the cross section including the rotation axis of the tire. The value of the arc was determined from several molds created and tested and evaluated by the mold, or was determined by a large number of numerical tests.

In addition, since the pattern design has a large degree of freedom, the basic pattern is grouped on the tire or the mold is actually made, and the tire is tested and manufactured to evaluate the actual vehicle, and the problem caused by the actual vehicle is solved by slightly modifying the pattern. Therefore, pattern design has become the most demanding field compared to tire shape and structural design.

However, in order to prevent hydroplaning and brake and traction performance during rain driving, pneumatic tires generally have rib grooves in the circumferential direction of the tire and lug grooves in the radial direction of the tires. So-called block patterns surrounded by grooves are common.

Such a block pattern requires the performance of the tire's kinetic performance, generally, straightness and cornering performance. Straightness performance requires a roughing force in the tire circumferential direction, and a relatively hard rubber is preferred. However, the cornering performance is required to have a grip force in the tire width direction, and relatively soft rubber is suitable for increasing the grip force at the cornering, but energy consumption is large due to the soft rubber.

Therefore, in recent years, a theoretical approach to designing a safe or quiet tire at high speeds in road conditions including dry, wet and ice snow has been tested, and grooves formed in the tread of the tire are plural according to mathematically calculated criteria. It is designed by the variable pitch repeat design cycle of. According to the design value, a tread having a transverse groove defining a pitch and pitch arrangement on the tire circumference and a hexapart divided in the circumferential direction is obtained. Here, the pitch indicates the relative length of the flesh, and the pitch arrangement refers to the order of the pitch used on the tire circumference. In addition, pitch may also use ratio of pitch length (pitch ratio).

Each pitch may be of various lengths, but is limited to about nine or less for practical purposes, and in certain pitch arrangements, the specific length of a particular pitch varies with the circumference of the tire (see Japanese Patent Application Laid-Open No. 4-232105).

However, the pitch and pitch arrangement are often determined by the improvement of the noise performance, the prevention of hydroplaning phenomenon, and the multilateral demand that meets the aesthetic appearance of the consumer, and a plurality of pitches are repeatedly used in the pitch arrangement. Therefore, the stiffness becomes nonuniform between the land parts by different pitches. Therefore, there is a problem in that uneven wear increases or roundness in manufacturing deteriorates between different pitches.

In view of the above facts, the present invention can design the best mode of a tire under given conditions, and at the same time, in order to obtain a plurality of performance rational performances, a design method of a pneumatic tire capable of increasing the efficiency of tire design and development. The purpose is to provide.

Disclosure of the Invention

Pneumatic tire design method of claim 1 for achieving the above object is (a) the shape of the block unit including the internal structure, the tire shape including the internal structure and the pattern of one part of the tire crown portion including the internal structure Tire basic model having a plurality of different shape basic models representing one shape selected from the shape of the land portion continuous in the direction, an objective function indicating physical quantity for tire performance evaluation, the shape or pattern of the block unit or the meat part (B) determining a design variable for determining a shape, a shape of a block unit, a shape selected from a pattern shape and a shape of a flesh, a constraint restricting at least one of a tire cross-sectional shape and a physical quantity for tire performance evaluation, and the like (b) By considering the constraints and changing the values of the design variables until the optimum value of the objective function is given, A step of obtaining the value, on the basis of the design variables that give an optimum value of (c) the objective function includes the step of designing the tire. The shape including the internal structure of step (a) means not only the outer shape but also the inner shape.

According to the invention of claim 2, the air tire designing method of claim 1, wherein the design variable determines the shape or pattern shape of the other block unit or the shape of the flesh by using at least one of the other basic shape models as a reference shape model. It is characterized in that it is intended to.

The invention of claim 3 is a method of designing a pneumatic tire according to claim 1, characterized in that for determining the shape or pattern of a block unit or the shape of a meat part by using the shape basic model predetermined by the design variable as a reference model. It is done.

According to the invention of claim 4, the air tire design method according to any one of claims 1 to 3, wherein in step (b), the sensitivity of the objective function is the ratio of the variation of the objective function to the unit variation of the design variable. And predicting a change amount of the design variable that gives an optimal value of the objective function while considering the constraint based on the sensitivity of the constraint, which is a ratio of the change amount of the constraint to the unit change amount of the design variable. It calculates the value of the objective function and the design variable when the quantity is changed to the predicted amount, and calculates the optimal value of the objective function based on the predicted value and the calculated value. It is characterized by obtaining the value of the design variable.

The invention of claim 5 is a method of designing a pneumatic tire according to claim 1, wherein in the step (a), the shape of the block unit including the internal structure, the pattern shape of one part of the tire crown part including the internal structure A selection target group including a plurality of tire basic models having a plurality of different basic shape models representing one selected shape among the shapes of the six parts continuous in the circumferential direction of the tire including the internal structure and the internal structure; In the tire basic model, an adaptive function that can be evaluated from the objective function, the design variable, the constraint, and the objective function and the constraint is determined, and in step (b), two tires of the selected target group are selected based on the adaptive function. Select the basic model and cross the design variables of each tire basic model with a certain probability to create a new tire basic model. At least one of generating and changing a part of design variables of at least one tire base model to generate a new tire base model is performed, and the objective function, constraints, and adaptation functions of the tire base model having changed design variables are obtained. Each tire basic model and the tire basic model which did not change the design variables are preserved, and the stored tire basic model is repeated until the predetermined number becomes a predetermined number, and a new group consisting of the predetermined number of the tire basic models is stored for predetermined procedure conditions. If it is determined whether the procedure is satisfied, and if the procedure is not satisfied, the new group is repeated as the selection target group until the selection target group satisfies a predetermined procedure condition and the predetermined procedure condition is satisfied. Objective function taking into account constraints among a given number of tire basic models To obtain the values of the design variables which give the optimum value is characterized.

According to the invention of claim 6, in the pneumatic tire design method according to any one of claims 1 to 5, the design variable should be formed by one shape selected from the shape of the block unit, the pattern shape, and the shape of the meat part. The angle of the surface connected to the surface of the tier, the height to the tire surface, the shape of the tire surface, the shape of the surface connected to the tire surface, the position, number, width, depth, slope, shape of the sipe and And a variable representing at least one of the sipe shapes of the length.

The invention according to claim 7 is characterized in that, in the pneumatic tire design method according to any one of claims 1 to 6, each of the tire basic models having a plurality of the shape basic models has a different length in the tire circumferential direction.

Step (a) of claim 1 is selected from among the shape of the block unit including the internal structure, the pattern shape of a part of the tire crown including the internal structure, and the land portion continuous in the circumferential direction of the tire including the internal structure. Tire basic model having a plurality of different basic shape models representing the shape of the dog, an objective function representing the physical quantity for tire performance evaluation, design variables for determining the shape or pattern of the block unit or the shape of the flesh, the shape of the block unit, the pattern shape and Constraints for determining at least one selected from the shape of the meat portion, the tire cross-sectional shape and the physical quantity for tire performance evaluation are determined. Further, the block unit tire crown portion including the internal structure and the land portion continuous in the tire circumferential direction include a medium formed only from a single rubber.

The shape basic model representing the shape of the block unit body may include a plurality of lines representing lines for specifying the outer shape of the block unit body and variables representing coordinate values of the inflection point. In addition, as a shape basic model showing the pattern shape of one part of the tire crown including the internal structure, a function capable of geometrically analyzing the pattern shape of the ground surface side of one of the tire crowns, for example, a rectangle and a ridge It can be configured as a function to determine the polygon. In addition, the shape basic model which shows the shape of the meat part which continues in the tire circumferential direction including an internal structure can be comprised from the function which shows a tire cross-sectional shape, and the variable which shows the coordinate value of an inflection point.

Each of these basic shape models includes the angle of the surface connected to the tire surface, the height to the tire surface, the shape of the tire surface, and the surface connected to the tire surface. At least one of the shape, the sipe position, the number, the width, the depth, the slope, the shape and the length of the sipe. In addition, the shape basic model may use the model by the method called the finite element method which divides into a some element, and may use the model by the analytical method.

The tire basic model has a plurality of different basic shape models among the basic shape models. For example, in order to design by a plurality of variable pitch iteration cycles, it is possible to use a model of a tread having a flesh defining a pitch and pitch arrangement on the tire circumference. In this case, a plurality of different pitches are formed on the tire circumference. In addition, the tire basic model may use the model by the method called the finite element method which divides into a several element, and may use the model by the analytical method.

In addition, each of the tire basic model, that is, the tire basic model having a plurality of shape basic models, may use a different tire circumferential length as in the invention of claim 7. There are tires (so-called pitch variation tires) in which tires are formed on the tire circumference at a plurality of different pitches in order to improve steering stability and staticness. This pitch variation tire usually changes only the length in the circumferential direction. Therefore, by designing a plurality of formed base models having different lengths in the circumferential direction as the tire base model, it is easy to design a tire that assumes a pitch variation tire.

As the objective function representing the physical quantity for performance evaluation, a physical quantity that governs the superiority of the kinetic performance of the tire such as block stiffness can be used. The design variable for determining the shape or pattern shape of the block unit body and the shape of the meat part is determined by a pattern selected from the shape of the block unit body, the pattern shape, and the shape of the meat part as described in claim 6. The angle of the surface connected to the tire flesh surface to be formed (that is, the block groove wall angle if it is a block unit), the height to the tire flesh surface (that is, the depth of the groove if the groove is formed), the shape of the tire flesh surface, the tire flesh Variables representing at least one of the shape of the face connected to the face, the position, the number, the width, the depth, the slope, the shape and the length of the sipe can be used. Constraints include tread thickness constraints, block stiffness constraints, and lateral angles (eg, block groove wall angles in the case of block units) formed of tires. In addition, the objective function, design variables, and constraints are not limited to the above examples, but may be variously determined according to the tire design purpose.

In the next step (b), the value of the design variable is calculated by changing the value of the design variable until the optimum value of the objective function is given while considering the constraints. In this case, constraints are based on the sensitivity of the objective function, which is the ratio of the variation of the objective function to the unit variation of the design variable, and the sensitivity of the constraint, which is the ratio of the variation of the constraint to the unit variation of the design variable, as claimed in claim 4 When considering the conditions and predicting the amount of change in the design variable that gives the optimal value of the objective function, and simultaneously changing the value of the objective function and the design variable by the amount corresponding to the predicted amount It is effective to calculate the value of the design variable that gives the optimal value of the objective function while calculating the constraint value of and considering the constraint based on the predicted value and the calculated value. By this, the value of the design variable is obtained when the value of the objective function becomes optimal in consideration of the constraints.

In step (c), the tire is designed by changing a shape basic model or the like based on a design variable that gives an optimal value of the objective function.

Therefore, a design variable that gives an optimal value of the objective function for the tire basic model having a plurality of different basic shape models, that is, a selected shape basic model representing the shape or pattern of the block unit or the shape of the flesh is determined. Therefore, a tire can be designed in which a shape determined by a pitch on the tire circumference is obtained and rigid uniformity is achieved.

As described in claim 2, the design variable may be set as at least one of the other basic shape models as a reference shape model, and for determining the shape or pattern shape of the other block unit or the shape of the flesh. By setting in this way, it is possible to design a tire which is based on the basic shape model set as the reference shape model and the rigid uniformity is made according to the reference shape model.

In addition, as in the invention of claim 3, the design variable may be set as a reference model based on the predetermined shape basic model and to determine the shape or pattern of the block unit or the shape of the flesh. By setting in this way, it is possible to design a tire in which a rigid uniformity or the like is formed according to the reference shape model based on the shape basic model set as the reference shape model. That is, in order to achieve a rigid uniformity, the shape basic model is determined in advance as an expected value, and a tire made of a rigid uniformity or the like is designed based on the reference shape model based on the shape basic model determined as the expected value.

In the invention of claim 5, in the step (a), the shape of the block unit including the internal structure, the pattern shape of one part of the tire crown part including the internal structure, and the shape of the land portion continuous in the circumferential direction including the internal structure, A selection target group including a plurality of tire models having a plurality of different shape basic models representing one selected shape is defined, and the objective function, the design variable, the constraint, and the objective function in each tire model of the selection target group. Determine the adaptation function that can be evaluated from and constraints.

Next, in step (b), selecting two shape basic models from the selection target group based on the adaptive function, and generating a new shape basic model by crossing design variables of each tire basic model with a predetermined probability; and At least one of generating a new tire basic model by changing a part of design variables of at least one tire basic model and obtaining the objective function, constraints, and adaptation functions of the tire basic model having changed design variables, and the tire basic model And preserving the tire basic model having changed design variables, and repeating until the number of stored tire basic models becomes a predetermined number, and judging whether a new group composed of the predetermined number of stored tire basic models satisfies predetermined procedure conditions. If the procedure is not satisfied, the new group is selected as the selection group. Repeat the process until the group satisfies the predetermined procedure, and select the value of the design variable that gives the optimal value of the objective function while considering the constraints among the predetermined number of shape basic models saved when the predetermined procedure is satisfied. Obtain The tire is designed by changing the shape basic model or the like in step (c) based on the value of the design variable giving the optimum value of this objective function.

In this case, in the tire basic model of which the design variable is changed in step (b), the sensitivity ratio of the objective function and the variation ratio of the constraint on the unit variation of the design variable are the ratio of the variation of the objective function to the unit variation of the design variable. Based on the sensitivity of the constraints, while predicting the variation of the design variable that gives the optimal value of the objective function while considering the constraints, the value of the objective function and the design variable when the amount of the design variable is significantly changed Calculate the value of the constraint when the quantity is changed to the predicted quantity, obtain the optimal function from the value of the objective function and the constraint, and preserve the basic model of the tire that did not change the basic model of the tire and the design variables. It is more effective to repeat until the tire basic model has become a predetermined number. By considering the constraints, the value of the design variable until the optimum value of the objective function is obtained is obtained. In addition, the adaptive function that can be evaluated in the objective function and the constraints can be used to obtain the adaptability to the tire model from the objective function and the constraints. In addition, the objective function, design variables, constraints and adaptation functions are not limited to the above examples but may be variously determined according to the tire design purpose. In addition, at the intersection of the design variables of the tire basic model, there is a method of exchanging design variables after a part or a predetermined portion of the design variables of the selected two tire models. In addition, a partial change of the design variables of the tire basic model includes a method of changing (muting) the design variables at a position determined by a predetermined probability.

As described above, according to the present invention, a design variable that gives an optimal value of an objective function in consideration of constraints can be obtained, and tires including other block shapes and patterns can be designed from this design variable. Unlike design and development, it is possible to evaluate the efficiency of the designed tire from the design of the optimum mode to the calculation of the optimum mode, mainly by computer calculation. It has the effect of being able to design block shapes and patterns.

1 is a schematic diagram of a personal computer used in an embodiment of the present invention.

2 is an image diagram showing a tire shape by pitch and pitch arrangement.

3 is a flowchart showing the flow of the tire shape design processing routine according to the first embodiment of the present invention.

4 is a flowchart showing the flow of an optimization routine.

5 is a flowchart showing the flow of an angular operation routine for determining a design variable.

Fig. 6 is a diagram showing one block-shaped basic model in the pitch group.

7 is an explanatory diagram for explaining a wall angle.

8 is a cross-sectional view of FIG. 7.

FIG. 9 is a diagram showing a shape of a tread face for explaining design variables by a plurality of wall faces.

10 is a diagram showing the shape of the tread of the chamfered block.

11 is a diagram showing the shape of the tread of a block having a curved wall.

FIG. 12 is a diagram showing a step surface shape of a block having a wall with curved surfaces in a direction different from that of FIG. 11.

13 is a flowchart illustrating another process flow of design parameter determination.

14 is an explanatory diagram for explaining another example of a design variable.

Fig. 15 is a diagram showing the shape of a sipe formed of blocks.

16 is a cross-sectional view taken along line II of FIG. 15.

17 is a diagram showing the length of the sipes formed up to the middle of the block.

18 is a flowchart showing the flow of the tire shape design processing routine according to the second embodiment of the present invention.

19 is a flowchart showing the flow of the tire shape design processing routine according to the third embodiment of the present invention.

20 is a flowchart showing the flow of cross processing.

21 is a flowchart showing the flow of mutation processing.

FIG. 22A is a diagram showing a continuous ridged mapping function, and FIG. 22B is a diagram showing a linear ridged mapping function.

FIG. 23A is a diagram showing a continuous curved function, and FIG. 23B is a diagram showing a linear curved function.

24 is a diagram showing a block according to the fourth embodiment.

25A and 25B are diagrams showing the stiffness per unit area with respect to the direction, and FIG. 25A shows the conventional stiffness before optimizing to make the tread thickness uniform, and FIG. 25B shows the stiffness after optimizing according to the present embodiment which makes the tread uniform. It was.

26th is a perspective view which shows the block which mutually faced in order to demonstrate the floor lift amount.

27 is an image view showing the tire shape according to the fifth embodiment.

FIG. 28 is a diagram showing the stiffness per unit area with respect to the direction after the thickness uniformity and the stiffness uniformity optimization have been performed according to the fifth embodiment.

29A to 29D show an indoor uniformity result of a tire made with pitch arrangement according to the configuration according to the fifth embodiment, FIG. 29A shows a result by RFV, FIG. 29B shows a result by high-speed RFV, 29C shows the results by the high speed TFV, and FIG. 29D shows the results by the LFV.

30 is a graph showing the measurement results of the tread thickness according to the fifth embodiment.

31A and 31B are diagrams showing stiffness per unit area with respect to direction in another tire as in the fifth embodiment, FIG. 31A is for conventional stiffness, and FIG. 31B is for tread thickness uniformity and stiffness uniformity. The stiffness after optimization by embodiment is shown.

32 is a diagram showing a tread pattern continuous from the pitch to the pitch according to the sixth embodiment.

Fig. 33A is a diagram showing the directionality of the block shapes of the pitch and the pitch, Fig. 33B is an image diagram showing the chamfering positions applied to the blocks of the pitch and the pitch, and Fig. 33C is a diagram showing the chamfering method.

Fig. 34 is an explanatory diagram for explaining the chamfering position in the tire circumferential direction shown in the blocks of the small pitch, the medium pitch, and the large pitch according to the first embodiment.

35A and 35B show block stiffness in the block chamfered according to the first embodiment, and FIG. 35A shows the conventional block stiffness, and FIG. 35B shows the block stiffness of the first embodiment.

FIG. 36 is an explanatory diagram for explaining a chamfering position in the tire width direction implemented with blocks of small pitch, medium pitch, and large pitch according to the second embodiment. FIG.

37A and 37B show block stiffness in the block chamfered according to the second embodiment, FIG. 37A shows the conventional block stiffness, and FIG. 37B shows the block stiffness of the first embodiment.

38 is an explanatory diagram for explaining a chamfering position in the tire width direction performed with the block of pitch according to the third embodiment.

FIG. 39 is an explanatory diagram for explaining a chamfering position in a tire width direction and a tire circumferential direction implemented with a block of medium pitch according to the third embodiment; FIG.

40 is an explanatory diagram for explaining a chamfering position performed with a block of medium pitches according to the third embodiment.

FIG. 41 is an explanatory diagram for explaining a chamfering position in the circumferential direction of the tire implemented with the block of the pitch according to the third embodiment; FIG.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, the example of embodiment of this invention is described in detail.

Fig. 1 shows an outline of a personal computer for carrying out the design method of the pneumatic tire of the present invention.

The personal computer includes a keyboard 10 for inputting data and the like, and a computer main body 12 that satisfies the constraints in accordance with a pre-stored program and calculates design variables that optimally, for example, maximize or minimize the objective function. And the CRT 14 for displaying the calculation result of the computer main body 12 and the like.

[First Embodiment]

First, the first embodiment will be described. The present embodiment is defined to improve quietness with low noise during driving, and the like, and uniforms the difference between the block stiffness in order to improve steering stability and wear resistance in a tire having a plurality of pitches and a pitch array in which the pitches are arranged. To determine the tire shape.

In addition, although each of the plurality of pitches has a pitch length, the pitch may correspond to a value obtained by integerizing the ratio of pitch lengths (hereinafter referred to as pitch ratio) for simplicity of calculation. For example, when three types of pitches are included: large pitch, medium pitch, and small pitch, each corresponds to an integer. In addition, to make the difference between the block stiffnesses uniform means that the distribution of stiffness is consistent or almost identical, that is, the difference in stiffness between groups of pitches that are different pitches with respect to pitch groups having opposite pitches on the pitch array. It says to be zero.

3 shows a processing routine of the program of the present embodiment. In steps 300 to 304, numerical input is made to enable numerical and analytical handling of the pitch array formed by the tread of the tire.

In detail, in step 300, a value or empirically obtained value for configuring the pitch arrangement of the static tire obtained in advance is input as a set value. This set value includes, for example, the total number N of pitches, the maximum pitch (pitch ratio: α _max = 11.0), and the minimum pitch (pitch ratio: α _min = 7.0). Alternatively, a pitch length value may be input.

In step 302, the number M of pitch types (M is a natural number, in the present embodiment, 3 is used as one of 2 to 9) is determined, and in step 304, the number of pitch types included in the pitch arrangement M is determined. A pitch array V having a total number of pitches of N and pitches is input, and this pitch array V is set as an initial value.

In other words, M pitches Yi (1 ≦ i ≦ 3) are mapped to natural numbers from 1 to 9, and the number of pitches N corresponds to each row of natural numbers where the pitch is an array value by specifying an array of N rows. To produce a pitch array (V). This pitch array V is calculated | required previously by experiment and calculation.

As shown in FIG. 2, the tire 20 determined by the pitch arrangement V includes three kinds of pitches, namely, small pitch Y ₁ , medium pitch Y ₂ , and large pitch Y ₃ . constructed and, small pitch (Y _1), the pitch group successive (PT _1), of the pitch (Y ₂₎ the pitch group successive (PT _2), for the pitch (Y ₃₎ the pitch group successive (PT ₃₎ It is formed on the tire 20. In the example of FIG. 2, the pitch group PT ₁ , PT _2, PT _3, PT _2, PT _2, PT _3, PT _2, PT _1, PT ₁ clockwise from the reference 20 _S of the tire 20. The pitch array V is configured to be continuous.

Further, in the present embodiment, each of the pitch groups PT ₁ , PT _2, PT ₃ is a plurality of pitches in which each of the small pitch Y ₁ , the medium pitch Y ₂ , _{and the} large pitch Y ₃ are continuous. Although described as being made, the present invention is not limited to this, and each of the pitch groups PT ₁ , PT _2, PT ₃ may be configured in a single pitch. In other words, at least one group of the pitch groups PT ₁ , PT _2, PT ₃ may consist of only one of the small pitch Y ₁ , the medium pitch Y ₂ , _{and the} large pitch Y ₃ .

Thus, the tire 20 which has a plurality of pitch groups in which a predetermined pitch is continuous and has a plurality of different pitch groups produces a difference in rigidity between these pitch groups. That is, in general, the stiffness block has a small rigidity in the tire circumferential direction but a large stiffness in the tire width direction. On the other hand, the block of the large pitch has a large rigidity in the tire circumferential direction but a small rigidity in the tire width direction. Since the stiffness difference is generated between the pitch group of the small pitch and the pitch group of the large pitch as described above, two pitch groups are designated in step 306, and optimization is performed to equalize the difference between the rigid groups between the pitch groups in the next step 308.

That is, in step 306, two pitch groups of the tire 20 specified by the pitch arrangement V are specified. In this embodiment, the case where the pitch group PT ₃ of a large pitch and the pitch group PT ₁ of a small pitch is specified is demonstrated. In the next step 308, these pitch groups PT ₁ and PT ₃ are optimized with the optimization routine of FIG.

In step 100 of Fig. 4 _, the block BL ₁ , BL ₃ included in each of the two pitch groups PT _1, PT ₃ specified in step 306 is used as a reference shape with one block of the tire shape specified by the pitch arrangement. The reference shape is modeled by a method that can obtain numerical and analytical block stiffness, such as finite element method, to represent the tire shape including the internal structure, and the shape basic model divided into a plurality of elements by mesh division. Obtained for each pitch group. The reference shape is not limited to one block of the tire shape in the natural equilibrium state, and may be any shape. Here, the modeling numerically identifies the tire shape, structure, material, and pattern. It digitizes the data into input data into a computer program created based on analytical techniques.

6 shows an example of the shape basic model of one block BL ₁ of the pitch group PT ₁ , and one block has eight points D _1, D _2, D _3, D _4, D _11, D _12, D _13, D ₁₄ ). In the figure, arrow A indicates the tire circumferential direction, arrow B indicates the tire width direction, and arrow C indicates the tire radial direction. In addition, PP represents one block of the answer surface, PL _1, PL _2, PL _{3, and} PL ₄ represent the answer surface shape, and D _1, D _2, D _{3, and} D ₄ represent the intersection point of the line representing the answer surface shape. Each vertex is shown. In this model, the answer surface (PP) is square, so the walls (HP _1, HP _2, HP _3, HP ₄ ) are connected to the answer surface (PP). In addition, the bottom surface BP is formed in parallel with the answer surface PP, and the bottom points D _11, D _12, D _{13, and} D ₁₄ are formed by the wall surface and the bottom surface.

The gap between the wall surface and the bottom surface may correspond to the so-called groove depth. In addition, the shape basic model can be divided into a plurality of elements, and may be divided into a plurality of elements by a plurality of normals on the tire surface, or may be divided into an arbitrary shape such as a triangle according to the design purpose.

The shape of the base model, a block (BL ₃₎ of the pitch group PT ₃ describes a code that is the same as the block (BL ₁₎ is omitted and the corresponding detailed description. Block (BL ₃₎ 8 opening _{(D 1, D 2, D} 3, D 4, D 11, D 12, D 13, D 14) that (D _5, D ₆ in response to the block (BL _1), D ₇ , D ₈ , D ₅₁ , D ₆₂ , D ₇₃ , D ₈₄ ). In addition, in response to the lines PL ₁ , PL ₂ , PL ₃ , and PL ₄ representing the tread shape of the block BL ₁ , the block BL ₃ represents the lines PL _5, PL _6, PL _7, PL ₈ . And points D ₅ , D ₆ , D ₇ and D ₈ corresponding to the vertex vertices D ₁ , D ₂ , D ₃ , and D ₄ of the block BL ₁ . Further, the block (BL ₁₎ a wall that is connected to the tread of the _{(HP 1, HP 2, HP} 3, HP 4) tread, the walls _{(HP 5, HP 6, HP} 7, HP 8) of the block BL ₃ in response to the Connected. Further, the bottom points D ₅₁ , D ₆₂ , D ₇₃ , and D ₈₄ are formed corresponding to the bottom points D ₁₁ , D ₁₂ , D ₁₃ , and D ₁₄ formed by the wall and bottom of the block BL ₁ .

In the next step 102, the physical quantity for tire performance evaluation determines the objective function indicated, the constraints for constraining the tire shape, and the tire shape. That is, design variables for determining a block shape are determined. In this embodiment, the objective function OBJ and the constraint G can be determined as follows in order to improve the steering stability and the wear resistance.

Objective function (OBJ): Makes the difference between block stiffness uniform.

Constraints (G): Make the tread thickness uniform to constrain the tire shape.

In addition, the difference between the block stiffness determined as the objective function OBJ determines the positions of the blocks BL _{1 and} BL ₃ provided on the tire for each pitch group PT ₁ and PT ₃ , and the tire circumferential direction in each block. From the stiffness of the tire to the stiffness in the width direction of the tire, obtain a known stiffness equation for each predetermined angle, and use the imbalance between the value and the difference in the stiffness difference between the blocks of the pitch groups PT _{1 and} PT ₃ . Can be calculated. Therefore _, the distribution of stiffness and the difference in stiffness between the pitch groups PT _{1 and} PT ₃ having opposite pitches on the pitch array are obtained. By obtaining the range and the angle difference value in the direction of obtaining the stiffness in advance, a block having directivity in the block stiffness can be designed.

Further, the tread thickness defined as the constraint G is a volume other than the volume required by the blocks BL _{1 and} BL ₃ when forming a tire having blocks BL _{1 and} BL ₃ provided on the tire, that is, a groove. It can be obtained from the volume of. That is, the flow volume of material such as rubber in the tire radial direction is determined according to the volume of the groove, and the tread thickness can be estimated from this value.

In addition, in this embodiment, the design variable employ | adopts a wall angle and is set by the angled face routine of FIG. In step 130 of this angle calculation routine, a reference point P is set at a predetermined point (for example, a tire center point) inside the tire as shown in FIG. In the next step 132, the range in which the wall surface of the block can be inclined is designated as the range in which the block shape is changed. In step 134, the wall surface of the block is selected by selecting a set of points that meet each other at the vertex of the answer surface. In the example of FIG. 7 there is selected that the wall (HP ₁₎ by selecting a (D _1, D ₂₎ of the block (BL ₁₎ of the pitch group (PT _1). In the next step 138 of the selected wall ridges, as a straight line, that is, base line a straight line in the tire radial direction of the reference point (P) passing through the line (PL ₁₎ In the example of Figure 7, as shown in Figs. 7 and 8 An angle θ ₁ constituting the wall surface HP ₁ selected as the reference line is calculated.

In the next step 140, it is determined whether there is a set of points that meet each other at the apex of the remaining road surface, and when the affirmative determination is made in the remaining step 140, the process returns to step 134 and repeats the above process. Thereby, angle (theta) ₁ , (theta) ₂ , (theta) ₃ ......) is hereafter represented by (theta) _i in general formula. However, i = 1,2 ... the maximum number of wall surfaces is computed. When the angle (θ _i) computed for all wall (negative determination in step 140), it is set as the design variables r _i a wall angle (θ _i) in the next step 142 the.

After determining the objective function (OBJ), the constraint (G) and the design variable (r _i ) in this way, in step 104 of FIG. 4, the objective function (OBJ) of the initial function (r ₀ ) of the design variable (r _i ) The initial value OBJ ₀ and the initial value G ₀ of the constraint G are calculated.

Next, in step 106 of Fig. 4, the design variable r _i for changing the shape basic model is changed Δr _i , respectively. In addition, changes in the design variables (r _i) is well possible to change all of the design variables (r _i) at the same time, and a plurality of design parameters of one or design variables (r _i) of the design variables (r _i) at the same time Δr _i The shape of each block formed by the changed angle of the side surface, that is, each point (D ₁ , D ₂ , D ₃ , D ₄ , D ₁₁ , D ₁₂ , D ₁₃ , D ₁₄ ) due to the change of the wall angle. The shape of each block after the change of the design variable Δr _i , that is, the shape correction model, is determined.

In step 110, in the image correction model obtained in step 108, the value of the objective function (OBJ _i ) and the constraint value (G _i ) of the objective function after changing the design variable Δr _i are calculated. The sensitivity of the objective function (dOBJ / dr _i ), which is the ratio of the variation of the objective function to the unit variation of, and the sensitivity of the constraint (dG / dr _i ), which is the ratio of the variation of the constraint to the unit variation of the design variable, Operate for each variable.

This sensitivity makes it possible to predict the degree of change in the value of the objective function and the constraint when the design variable is changed by Δr _i . This sensitivity may be analytically determined depending on the method used for modeling the tire and the nature of the design variables, so that the calculation of step 110 is unnecessary at that time.

In the next step 114, the objective function is satisfied by the mathematical programming method using the initial value of the objective function (OBJ ₀ ), the initial value of the constraint (G ₀ ), the initial value of the design variable (r ₀ ) and the sensitivity. Predict the variation of the design variable that minimizes, that is, minimizes the difference between block stiffness. Using the predicted values of the design variables, the shape correction model is determined in the same manner as in the steps 115 through 108, and at the same time, the objective function value is calculated. In step 116, it is determined whether the objective function value is converged by comparing the difference between the objective function value OBJ calculated in step 115 and the initial value OBJ ₀ of the objective function calculated in step 104 and a value previously input. If it is determined that the objective function value has not been converged, steps 104 through 116 are repeatedly executed with the design variable values obtained in step 114 as initial values. When it is judged that the value of the objective function is converged, the value of the design variable at this time is satisfied, and the value of the design variable that minimizes the objective function while satisfying the constraints is determined. Determine the shape of each block constituting each pitch. Thereby, the shape of the two pitch groups which comprise a part of tire is determined.

In this embodiment, the case where one block wall surface is four is mentioned as an example, However, the application of the block in which many wall surfaces were formed is also possible. It can be considered that the block on which the plurality of wall surfaces are formed has a plurality of lines representing the shape of the answer surface in which the answer surface forms a polygonal shape. For example, as shown in FIG. 9, the answer surface PPa of one block is based on four points D ₁ , D ₂ , D ₃ , and D ₄ , and a point D ₂ and a point D ₃ . Form a point (D _21, D _22, D _23, D ₂₄ ) between them, and instead of the line (PL ₂ ) (FIG. 6) joining the point (D ₂ ) and the point (D ₃ ), the lines (PL ₂₁ , PL ₂₂ , PL ₂₃ , PL ₂₄ , PL ₂₅ ) are formed. Similarly, the line in place of the points (D ₁₎ and point (D ₄₎ point between to form a _{(D 41, D 42, D} 43, D 44) lines _{(PL 4) (PL 41,} PL 42, PL 43, PL ₄₄ , PL ₄₅ ) are formed. Therefore, the road surface PPa is connected to a continuous wall surface (HP ₁ , HP ₂₁ , HP ₂₂ , HP ₂₄ , HP ₂₅ , HP ₃ , HP ₄₁ , HP ₄₂ , HP ₄₃ , HP ₄₄ , HP ₄₅ ) in each line. At least one of these walls (HP ₁ to HP ₄₅ ) can be defined as a design variable.

Also, as shown in Fig. 10, it is also easy to apply to a so-called chamfered block shape in which the angle of one block is reduced only by a predetermined amount. Tread (PPb) of one block in the example of FIG. 10 is an example of a case to a single flat side D ₁ and D ₄ side by the four points _{(D 1, D 2, D} 3, D 4) as standard. If chwiryang are the coordinates of the point (D ₁₎ dot to be formed side of each is reduced in the (D _1A, D _1B) and point (D ₄₎ point (D _3A, D _3B) which each have less formed on the side of the block It can be obtained by deciding. Therefore, if the amount of chamfering is set in advance, each position to be reduced, that is, a point can be determined, and at least one of the wall surfaces including the wall to be formed by the chamfering can be determined as a design variable.

In addition, although the case where the line which forms the wall surface of a block is straight was demonstrated above, a line is not limited to a straight line, As shown in FIG. 11, the curve shown by a predetermined function may be sufficient. In the example of FIG. 11, the answer surface PPc of one block has four points D ₁ , D ₂ , D ₃ , and D ₄ , but a line PL _1C joining the point D ₁ and the point D ₂ . The line PL _{3C represented} by this predetermined function (e.g., multidimensional curve and hyperbolic curve) and combining the points D ₃ and D ₄ is also a predetermined function (e.g., multidimensional curve and hyperbolic curve). appear. In this case, the lines PL _{1C and} PL _3C may be defined by Lagrangian interpolation or the curve itself may be changed into a design variable. In addition, although the wall surface continued from each line of the road surface PPc becomes a curved surface, one wall surface may be divided | segmented into a micro area | region (microplane), and a wall surface may be determined using raglan interpolation etc. In addition, as shown in FIG. 10, the shape of the wall surface continuous to the answer surface PPd may be made into a curved surface.

Thus, in the present embodiment, since the rigidity can be uniformized in all directions in the block unit, use is not applied to the widthwise division tread and does not affect the shape of the block on the ground surface of the tire tread portion. According to the frequency and the required performance, it is possible to steal the lug groove shape and the rib groove shape of the tire, and to optimize the tire in the width direction of the tire, and to achieve high wear resistance and movement performance of the tire.

In addition, the design variable may employ a squareness. This design variable is set by execution of the squareness arithmetic routine of FIG. 13 instead of the process of FIG. In step 150 of the rectangular calculation routine, as shown in FIG. 14, a reference point Q is set at a predetermined point (vertex D _{1 in} the example of FIG. 14) of the tire tread surface. In the next step 152, the range in which the tread line of the block can be tilted is designated as the range for changing the block shape (tread face shape). In step 154, the wall surface of the block is selected by selecting a point for inclining the line among the points viewed from each other with the designated vertex of the answer surface. In the example of FIG. 14, the line PL ₄ continuous to the wall surface HP ₄ is selected by selecting the point D ₄ . It is also preferable to select the corresponding line PL ₂ in accordance with the selection of the line PL _{4 in} order to keep the opposing lines in parallel as a block shape. In the next step 156, an angle δ that forms a reference line (a straight line parallel to the tire width direction) with the selected line PL ₄ is calculated. This angle δ is a square degree.

In the next step 158, the coordinate points of the points D ₃ and D ₄ defining the lines PL ₂ and PL ₄ as variables for changing the squareness are obtained. The tread shape is not without changing the length (L ₁₎ to the length (L ₂₎ is also pre-(δ) square without changing the length of each of the tire so determined main direction of the tire width direction. To do this, the points D ₃ and D ₄ may be moved in the tire circumferential direction. This movement amount S _i is set as a design variable r _i .

Another example of the design variable is the number of sipes to be formed in the block, and the sipes include the width Wa and the slope γa as shown in FIG. In addition, there is a depth wb of the sipe and a slope γb in the block as shown in FIG. In addition, the sipe is not limited to passing through the block, and there is a sipe length wc when forming to the middle of the block as shown in FIG.

When the optimization of the two pitch groups is completed as described above, in step 310 of FIG. 3, it is determined whether the above processing is finished for all the pitch groups in the pitch array V, and when there is a remaining pitch group, in step 306 Step 310 is repeated.

When the optimization is finished for all pitch groups in the pitch array V, the process proceeds to step 312, in which the block shape constituting each pitch of each pitch group is determined and the block shape of all pitch groups constituting the tire is determined. Determine the shape of.

In this way, the difference between the stiffness can be uniformized for each pitch group, so that the tire lug groove shape and the rib groove shape, etc. are appropriately adjusted without affecting the pitch size of the pitch array formed on the tire red portion, and the tire width direction position. Can be optimized and the tire's wear resistance and interlocking performance are highly compatible.

Second Embodiment

Next, a second embodiment will be described. In the above embodiment, the difference between the stiffnesses of the two pitch groups is equalized, but the value of the uniform block stiffness may be unbalanced in many pitch groups. Therefore, in this embodiment, the difference between rigidity is stabilized uniformly. In addition, since this embodiment is substantially the same structure as the said embodiment, the same code | symbol is attached | subjected to the same part and detailed description is abbreviate | omitted.

As shown in Fig. 18, when the optimization of the two pitch groups is completed as in the above embodiment, it is determined in step 320 whether the processing is finished for all the pitch groups in the pitch array V, and there may be remaining pitch groups. At that time, any pitch group of the two pitch groups optimized in step 322 is set as the reference pitch group. In the next step 324, any one of the remaining pitch groups is designated as the optimization pitch group, and the optimized optimization pitch group is optimized in the next step 326. In this step 326, only the optimized pitch group is changed and optimized without changing the design variable of the reference pitch group as the design variable (FIG. 4).

When the optimization of the optimization pitch group is finished, it is determined in step 328 whether the optimization is finished for all the pitch groups in the pitch array V, and if there is a remaining pitch group, step 328 is repeated in step 324. When the optimization is finished for all the pitch groups in the pitch array V, the process proceeds to step 330 to determine the block shape constituting each pitch of each pitch group and to determine the block shape of all pitch groups constituting the tire. Determine the shape.

In this way, since the difference between the stiffness can be uniformized for all pitch groups, it does not affect the pitch size of the pitch array formed on the tire tread portion, and the block stiffness value is not unbalanced, and the lug groove shape and rib groove shape of the tire are It is possible to optimize the back and the like at the tire width direction position, and to achieve high wear resistance and movement performance of the tire.

In each of the above embodiments, two pitch groups are designated to equalize the difference between the stiffness, but the value of the uniform block stiffness may be unbalanced. Therefore, the difference between the stiffnesses can be stabilized uniformly. For example, an arbitrary pitch group may be defined as the reference pitch group of the tire 20 and the other pitch group may be optimized to make the difference between the stiffness uniform with respect to the reference pitch group. In this case, any pitch group can use the pitch group by well-known data previously experimentally calculated. In addition, the block stiffness may be determined in advance, and the difference between the stiffnesses of the two pitch groups may be equalized in the block stiffness.

[Third Embodiment]

Next, a third embodiment will be described. This embodiment designs the block shape of a tire by a genetic algorithm. Design variables different from the above embodiment are used. In addition, since this embodiment is substantially the same structure as the said embodiment, the same code | symbol is attached | subjected to the same part and detailed description is abbreviate | omitted.

19 shows the program processing routine of this embodiment.

In step 200, each block shape of the plurality of pitch groups included in V is modeled by a method that can numerically and numerically obtain the block stiffness of a tire such as the finite element method, and obtain a shape basic model including an internal structure. . N is input by the user in advance. The one-block shape model used in this embodiment is the same as that shown in FIG. 6 of the first embodiment.

In the next step 202, the objective function representing the physical quantity for tire performance evaluation, the constraints for constraining the tire shape, and the design variables for determining the block shapes of the N shape models are determined. In this embodiment, the objective function OBJ and the constraint G are determined as follows in order to improve the wear resistance and the steering stability.

Objective function (OBJ): Makes block stiffness uniform in all directions.

Constraints (G): Make the tread thickness uniform to constrain the tire shape.

Further, the wall surface angle, which is a design variable, is determined for each of the N shape models by the angular calculation routine of FIG. 5 described in the first embodiment. Since this processing is the same as in the first embodiment, the description is omitted.

By repeating the angle calculation routine N times, the objective function OBJ, the constraint G, and the design variables r _iJ (J = 1, 2, ..., N) of each of the N shape models are determined. In operation 204, the objective function OBJ _J and the constraint G _J of the design variable r _iJ of each of the N tire shape models are calculated.

In the next step 206, the adaptive function F _J of each of the N shape models is calculated using the objective function (OBJ _J ) and the constraint (G _J ) of each of the N tire shape models obtained in step 204. Calculate according to In this embodiment, for example, by uniformizing block rigidity in all directions, the value (adaptability) by the adaptation function becomes larger when the standard deviation of the block rigidity becomes smaller in all directions.

or

or

only,

c: integer

r: penalty coefficient

Φ _J = penalty coefficient of Jth tire shape model of N shape models

     (J = 1,2,3,…, N)

In addition, c and γ are input by the user in advance.

In the next step 208, two cross-shaped shape models are selected from the N tire shape models. As a selection method, a commonly used adaptation proportional strategy is used, and the probability (Pe) of selecting each of the N shape models, e, is represented by the following equation.

However, Fe: adaptive function of individual (e) in N tire shape models

F _J = J-th adaptive function of N tire shape models

         J = 1,2,3,... , N

In the present embodiment, the adaptive proportional strategy is used as the selection method, but the expectation strategy, the rank strategy, the elite preservation strategy, the tournament selection strategy, or the GENITOR algorithm shown in the genetic algorithm (edited by Hiroaki Kitano) are used. You may also do it.

In the next step 210, it is determined whether the two selected shape models intersect with the probability T previously input by the user. Intersection here refers to exchanging a part of elements of two shape models as described later. If it does not intersect with the negative determination, the flow proceeds to step 216 as it is. On the other hand, when crossed with affirmative determination, two shape models are crossed as described later in step 214.

The intersection of the two shape models is performed by the intersection routine shown in FIG. First, the two shape models selected in step 208 are the shape model a and the shape model b, and at the same time, a design variable vector including the design variables of each of the shape models a and b is represented, and the design variable vector of the shape model a is V _r ^a. = (r ₁ ^a , r ₂ ^a …, r ₁ ^a ,…, r _n-1 ^a ), then designate the design vector of shape model b as V _r ^b = (r ₁ ^b , r ₂ ^b ,…, r _i ^b m…, r _n-1 ^b ). In operation 250 of FIG. 20, a predetermined random number is generated, and the intersection place i regarding the design variable vector of the shape models a and b is determined according to the random number.

In the next step 252, the distance d is found for the design variables r ₁ ^a and r ₁ ^b of the shape models a and b determined to intersect according to the following equation.

In the next step 254, the minimum value B _L and the maximum value B _U of the acquisition range of r _i ^a and r _i ^b are used, and a normalization distance d 'is obtained according to the following equation.

In step 256, the mapping function Z (X) (O≤X≤1, O≤Z (X) ≤0.5) of the mountain form is distributed by appropriately distributing the value of the normalization distance d 'as shown in Figs. 19A and 19B. Use to find the function value (Z _ab ) according to the following equation.

After the function value Z _ab is obtained in this way, the new design variables r _i ' ^a , r _i ' ^b ) are obtained in step 258 according to the following equation.

or,

In this way, after r _i ' ^a and r _i ' ^b are obtained, a design variable vector V _r ' ^a and V _r ' ^b , which is ^a new design variable in step 260, is obtained as follows.

Vr ' ^a = (r ₁ ^a , r ₂ ^a ,…, r _i ' ^a , r _{i + 1} ^b ,…, r _n-1 ^b )

Vr ' ^b = (r ₁ ^b , r ₂ ^b ,…, r _i ' ^b , r _{i + 1} ^a ,…, r _n-1 ^a )

In addition, the minimum value B _L and the maximum value Bu of the acquisition range of r _i are previously input by the user. The mapping function Z (x) may be a curved function as shown in Figs. 20A and 20B. In the above example, the crossover point (i) may be used in one place or in addition to the multiple point crossover or single form crossover shown in the genetic algorithm (edited by Kitano Hiroaki).

After generating two new shape models by this intersection, in step 216 of FIG. 19, it is determined whether to mutate with the probability S previously input by the user. This mutation is intended to make small changes to some of the design variables as described below, and to increase the probability of including the parent population that is the optimal design variable. In the case of not mutating the negative judgment in step 216, in step 226, the two current shape models are directly moved to the next step 222. In the case of affirmative mutation, the mutation is carried out as follows in step 220.

This mutation is shown in Fig. 21 and is performed by the mutation routine.

First, in step 262, a random number is generated and the location (i) of the mutation is determined by the random number. In the next step 264, the distance d '

O≤d'≤1

Determined by random numbers in the range of.

In the next step 266, the mapping function Z (x) of the mountain form shown in Figs. 22A and 22B (0≤X≤1 and 0≤Z (x) ≤0.5), or the mapping function Z of the curve shown in Figs. 23A and 23B. Using (x), the function value Zd is obtained according to the following equation.

Zd = Z (d ')

After the function value Zd is obtained in this way, a new design variable r _i 'is obtained in step 268 according to the following equation.

or

After the design variable r _i 'is obtained in this way, the design variable vector V _r ', which is a new design variable obtained in step 270, is as follows.

Vr '= (r ₁ , r ₂ ,…, r _i ', r _{i + 1} ,…, r _n-1 )

In this way, the values of the objective function and the constraints of the two newly created shape models are calculated in step 222 of FIG. In the next step 224, the adaptive function is calculated using the equation (4) as in the example of the embodiment from the obtained value of the objective function and the value of the constraint. In the next step 226, the two shape models are preserved.

In the next step 228, it is determined whether the number of the shape models saved in step 226 has reached N. If not, the process repeats the steps 208 and 228 until there are N pieces. On the other hand, if the number of shape models reaches N, the procedure is determined in step 230. If not, the N shape models are updated to the shape models stored in step 226, and step 230 is repeatedly executed. . On the other hand, if the procedure is determined in step 230, the objective function is maximized while satisfying the constraints with the value of the design variable of the shape model whose maximum value of the objective function is satisfied while satisfying the constraint among the N shape models. As the value of the design variable, the shape of the tire is determined using the value of this design variable in step 232.

The procedure of step 230 is regarded as a procedure if any one of the following conditions is satisfied.

1) The number of households reached M.

2) The number of lines with the large value of the first function is more than q% of the total.

3) The maximum objective function value is not continuously updated in p generations.

In addition, M, q, and p are previously input by the user.

As described above, in the present embodiment, the difference between the stiffness can be equalized between the pitch groups, so that the tire lug groove shape, the rib groove shape, the sipe shape, and the like are optimized according to the required performance such as cornering performance and straightness performance. The tire can be optimized in the widthwise position, and the tire wear resistance and movement performance can be highly compatible.

Fourth Embodiment

The following fourth embodiment will be described. In the above embodiment, the difference between the stiffness of the pitch or the pitchco is uniform. In this embodiment, the groove wall angle is optimized to uniform the tread thickness. In addition, since this embodiment is substantially the same structure as the said embodiment, the same code | symbol is attached | subjected to the same part and detailed description is abbreviate | omitted.

As shown in Fig. 24, the block shape has a long side of the length LB in the tire circumferential direction and at the same time has a short side of the length LA or a height DP in the tire width direction crossing the tire circumferential direction. have. The groove walls HP _{1 and} HP ₃ continuous to the short side of the length LA are set to the same groove wall angle ε, and the groove walls HP ₂ and HP ₄ continuous to the long side of the length LB are the same groove wall angle ( ø).

The groove wall angles ε, ø of this block are optimized as described in the above embodiment. In this embodiment, the objective function OBJ and the constraint condition G are determined as follows in order to uniformize the tire-shaped uniformity.

Objective function (OBJ): Makes the tread thickness uniform to constrain the tire shape.

Constraints (G): Make the difference between block stiffness uniform.

In this embodiment, since the tread thickness can be made uniform for each pitch or pitch group, the tire tread thickness nonuniformity can be eliminated without being influenced by the pitch magnitude of the pitch arrangement formed in the tire tread portion.

As a result of optimizing the block with the above objective function and constraints, each angle of groove wall angle ε = 10 degrees for groove pitch and groove wall angle ø = 3.5 degrees is obtained, and groove wall angle ε = 3 degrees for large pitch, In addition, the respective angles of the groove wall angle? = 10 degrees were obtained. The difference in tread thickness at this time was improved to 0.01 mm compared to 0.08 mm. 25A and 25B show the stiffness per unit area with respect to the direction, FIG. 25A shows the conventional stiffness before the optimization to make the tread thickness uniform, and FIG. 25B shows the stiffness after the optimization according to the present embodiment with the tread thickness uniform. . In this embodiment, the tire-shaped uniformity is uniform, but as understood in FIGS. 25A and 25B, the difference between the rigid pitches is somewhat matched or slightly improved to the conventional shape.

[Fifth Embodiment]

Next, a fifth embodiment will be described. In the above embodiment, the difference between the stiffness of the pitch or the pitch group was equalized, but the improvement of the difference between the stiffness pitch was very slight. In this embodiment, the groove wall angle is optimized to equalize the tread thickness and equalize the difference between the stiffness of the pitch or the pitch group. In addition, since this embodiment is substantially the same structure as the said embodiment, the same code | symbol is attached | subjected to the same part and detailed description is abbreviate | omitted.

When the groove wall angle is optimized, the groove wall angle has a variable angle range because the distance between the blocks facing each other is determined by the pitch arrangement and the groove depth is also determined. Therefore, there is a limit to the optimization by the groove wall angle only. In this embodiment, the floor lift amount is introduced into the design variable in order to equalize the tread thickness and the difference between the stiffness of the pitch or the pitch group.

As shown in Fig. 26, the floor lift amount is the height DS in the tread between the opposite blocks. In addition, as shown in FIG. 27, in the present embodiment, the tire 20 determined by the pitch arrangement V has three kinds of pitches, namely, small pitch (Y ₁ ) _, medium pitch (Y ₂ ), and large pitch (Y). ₃₎ it consists including small pitch (Y _1), a pitch group successive eight (PT _1), of the pitch (Y ₂₎ the pitch group consecutive four (PT _2), for the pitch (Y ₃₎ The pitch group PT _{3 in} which 5 is continuous is formed on the tire 20. In the example of FIG. 27, the pitch group PT _2, PT _3, PT _2, PT ₁ PT _2, PT _3, PT _2, PT _1, PT _2, PT ₃ clockwise from the reference 20 _S of the tire 20. _, PT _2, PT ₁ ) is configured such that the pitch array V is continuous.

In addition, in the present embodiment _, each of PT _1, PT _2, PT ₃ has been described as being composed of a plurality of pitches each of the small pitch (Y ₁ ), the medium pitch (Y ₂ ), and the large pitch (Y ₃ ). The invention is not limited to this, and each of the pitch groups PT ₁ , PT ₂ , PT ₃ may be composed of a single pitch. That is, at least one group of the pitch groups PT ₁ , PT ₂ , PT ₃ may be formed only in one of the small pitch Y ₁ , the medium pitch Y ₂ , and the large pitch Y ₃ .

In the tire 20 having a plurality of pitch groups in which the predetermined pitches are continuous and a plurality of different pitch groups, optimization of the groove wall angle and the floor lift amount is performed to optimize the thickness of the tread and the difference between the stiffness of the pitch or the pitch group. Say. In this embodiment, the floor rise amount is added to the thing of the said embodiment as a design variable.

In this embodiment, the difference between the tread thickness and the stiffness of the pitch or the pitch group can be equalized for each pitch or between each pitch group, so that the tire tread thickness nonuniformity can be eliminated without affecting the pitch magnitude of the arrangement formed in the tire tread portion. While being able to eliminate, the difference between the stiffness of a pitch or a pitch group can be made uniform.

As a result of optimizing the block according to the objective function, constraints, and design variables, the groove wall angle ε = 10 degrees and the groove wall angle ø = 2 degrees and the floor rise of 1 mm are obtained for the pitch. An angle with a groove wall angle ε of 3 degrees and a groove wall angle of ø = 10 degrees was obtained. The difference in tread thickness at this time was 0.01 mm. Fig. 28 shows the stiffness per unit area with respect to the direction, and as understood from this figure, the uniformity of the tire shape is uniform, and the difference between the pitches of the stiffness is coincident to some extent.

Here, the result of having produced the tire by the pitch arrangement by the said block structure and verifying the effect is shown below. The tires were fabricated by applying a three-pitch, three-mounted arrangement on the 195 / 65R 14 tires and the indoor uniformity was measured. The results are shown in FIG. 29. FIG. 29A shows the result by RFV (speed 10 km / h), FIG. 29B shows the result by high speed RFV (speed 120 km / h), FIG. 29C shows the result by high speed (speed 10 km / h) TFV, and FIG. 29D shows The result by LFV (speed 120 km / h) is shown. Incidentally, the hatched bars in the drawings indicate conventional tire results and the white bars indicate the results of tires to which the present embodiment is applied. As understood from the figure, an improvement of 11 to 50% was found in the tire according to the present embodiment compared to the conventional tire. In addition, as a result of measuring the steering stability by loading in the actual car, the result was improved to 6.5 compared to the conventional 5.5.

In addition, the 20 mm flat load was compared to verify the rigidity of the pattern mounting tire. In addition, this verification was performed by FEM analysis. If there is about 20% difference in block stiffness, it is 350.5kgf with the only pitch on the ground plane and 352.1kgf with the pitch only on the ground plane, resulting in a difference of 1.6kgf. Optimizing the groove wall angle and floor rise as in this embodiment, and equalizing the tread thickness and the difference between the stiffness of the pitch or the pitch group, the result is improved to 352.0 kgf in peach pitch and the stiffness difference to 0.1 kgf. It became.

Next, the present inventors verified the effect of making the tread thickness uniform. The result of having measured the tread thickness by manufacturing the tire of the structure designed by this embodiment as mentioned above is shown in FIG. As will be understood from the figure, the tread thickness is made within a difference of 0.05 mm, including a measurement error of about 0.02 mm with respect to a difference of 0.12 mm of the prior art. In addition, 20mm flat load was compared to verify the stiffness of this tire. In addition, this verification was performed by FEM analysis. If the thickness of the tread is increased to 0.1 mm, the thickness is increased from 352.1 kgf to 358.4 kgf, and the rigidity of 1.3 kgf is improved.

Next, the result of manufacturing experiment with respect to the other tire is shown. Here, the result produced by applying to the tire of RE711 is shown. 31A and 31B show the stiffness per unit area with respect to the direction, FIG. 31A shows the conventional stiffness, and FIG. 31B shows the stiffness after optimization by this embodiment in which the tread thickness is made uniform and rigid. As understood from Fig. 31A and Fig. 31B, the difference between the stiffness pitches is almost identical to that of the present embodiment compared with the conventional one.

[Sixth Embodiment]

Next, a sixth embodiment will be described. In the above embodiment, the case where the shape is optimized is explained, but in the present embodiment, the structure is changed to suppress the change in the grounding characteristic. In addition, this embodiment is substantially the same structure as the said embodiment, the same code | symbol is attached | subjected to the same part, and detailed description is abbreviate | omitted.

In this embodiment, the tire 20 determined by the pitch arrangement V shown in FIG. 27 is employed. In addition, as an example, the case where the tire is applied to a groove depth of 7.0 at 195 / 65R14 is described as an example. In addition, in this embodiment, it applies to the block-shaped central block of a longitudinal direction. FIG. 32 shows the tread patterns of portions continuous with the small pitch Y ₁ , the medium pitch Y ₂ , and the large pitch Y ₃ . The block BL _S of the small pitch Y ₁ is a length LX _{1 in the} tire width direction and a length LY _{1 in the} tire circumferential direction. Moreover, the block BL _M of the medium pitch Y ₂ is the length LX _{2 in the} tire width direction and the length LY _{2 in the} tire circumferential direction. Similarly, the block BL _L of the large pitch Y ₃ is the length LX ₃ in the tire width direction and the length LY _{3 in the} tire circumferential direction. In this embodiment, a case where LX ₁ + LX ₂ = LX ₃ is set to the same length (= 24 mm) in each block, and LY ₁ = 21, LY ₂ = 27, and LY ₃ = 33 is set. Explain.

Next, the chamfering position and the chamfering method which concern on this embodiment are demonstrated. As shown in Fig. 33A, for example, when the block BL _S of the small pitch Y ₁ and the block BL _L of the large pitch Y ₃ are taken as an example, the blocks are rhomboid, so that the angles are four and face each other. The angles are approximately the same shape. With respect to these blocks, as shown in Fig. 33B, the blocks BL _S of the pitch Y ₁ chamfer two angles in the tire width direction, and the blocks BL _L of the large pitch Y ₃ are in the tire circumferential direction. Chamfer 2 corners. As shown in Fig. 33C, the chamfered tread is a predetermined length LZ along the ridge at the point D ₁ on the side of the answer surface of the vertices D ₁ and D ₁₁ before chamfering, as the chamfering starting position. It is performed by cutting toward the side point D ₁₁ . By chamfering in this way, the uniformity of the difference between the blocks can be improved.

In the above, the case where one of the tire main direction and the tire width direction is chamfered is taken as an example, but the present invention is not limited thereto, and chamfering may be performed on at least one of the tire main direction and the tire width direction for each block.

The chamfering method is not limited to cutting toward the point D ₁₁ on the tread side, and may be cut to a depth equal to a predetermined length LZ or cut to a predetermined predetermined depth along the ridge line.

Next, the Example in the said 6th Embodiment is demonstrated.

[First Embodiment]

This embodiment is applied when the block is chamfered in the tire circumferential direction. As shown in Fig. 34, the block BL _S of the small pitch Y ₁ is not chamfered in the present embodiment, and the block BL _M of the medium pitch Y ₂ is 2 mm at an angle in the circumferential direction of the tire. subjected to chamfering blocks (BL _L) of large pitch (Y ₃₎ There was carried out a single flat 5㎜ of each of the tire main direction. Next, the present inventors conducted a block stiffness FEM analysis experiment on the block subjected to the area charging to obtain the results shown in FIG. 35. Fig. 35A shows the block stiffness per unit area for each of the pitch and large pitches of the conventional design without chamfering, and Fig. 35B shows the units for each of the pitch and large pitches according to the present embodiment where chamfering was performed. Block stiffness per area is shown. As understood from the figure, the block stiffness is improved.

The present invention has also been verified by actually applying the block to a tire. In the measurements of indoor uniformity, the third component is improved, 10% better for RFV, and 15% better for TFV. In addition, the steering stability was measured by loading the tire into the vehicle, and the result was improved to 5.5 from that of the conventional 5.0.

Second Embodiment

This embodiment is applied when the block is chamfered in the tire width direction. As shown in Fig. 36, in this embodiment, the block BL _L of the large pitch Y ₃ is not chamfered, but the block BL _S of the small pitch Y ₁ is chamfered 2 mm at an angle in the tire width direction. 0.8 mm was chamfered to the block BL _{m by} the angle of the tire width direction.

Next, the present inventors conducted a block stiffness FEM analysis experiment on the block chamfered above to obtain the results shown in FIGS. 37A and 37B. Fig. 37A shows the block stiffness per unit area for each of the pit pitch and the large pitch without chamfering. Indicated. As understood from the figure, the block stiffness is improved.

In addition, the present invention validated the block by actually applying it to the tire. In the measurement of indoor uniformity, the tertiary component was improved, 10% improved for RFV, and 10% improved for TFV. The steering stability was measured by loading the tires into the vehicle and the result was improved to 5.25 from that of the 5.0.

Third Embodiment

This embodiment is applied when the actual tire block is chamfered.

In this embodiment, a tire of 275 / 40ZR 18 type with a one-side tread width of 140 mm and a pitch length of 50.91: 80.01 is adopted.

As shown in Figure 38, the chamfer _(S M) of the block (BL _S) has in each of the tire width direction 2㎜ a predetermined pitch (Y ₁₎ in the present embodiment was conducted. That is, as shown to the left of FIG. 33B, each block of the pitch Y ₁ was chamfered in two angles of the tire width direction. As shown in FIG. 39, the block BL _M of the medium pitch Y ₂ is subjected to chamfering of 1 mm at an angle in the width direction of the tire (M _m2 ), and also to chamfering of 2 mm in the tire circumferential direction (M _m1 ). Is carried out. That is, the chamfered angle each of two second angle Thai main direction of the tire width direction was carried out on each block of the pitch (Y ₂₎ of the as shown in Figure 40. In addition, the block BL _L of the large pitch Y ₃ was chamfered 4 mm at an angle in the tire circumferential direction. That is, as shown in the right side of FIG. 33B, each block of the large pitch Y ₃ was chamfered M _L at two angles in the tire circumferential direction.

MEANS TO SOLVE THE PROBLEM As a result of measuring the steering stability by loading a tire in a real vehicle with respect to the actual tire which carried out the said chamfering, the present inventors obtained the result that it improved to 6.5 compared with 5.5 conventionally.

As mentioned above, although the Example of this invention was described, the Example of this invention has an aspect of the following various technical matters in addition to the requirements of a claim.

8. Pneumatic tire of a shape designed by the pneumatic tire design method of any one of claims 1 to 7.

9. The shape basic model of peach and the shape basic model of large pitch as described in item 7, wherein the pattern shape of one part of the tire crown part including the internal structure and the shape of the meat part continuous in the circumferential direction of the tire including the internal structure In the tire basic model consisting of a pneumatic tire having a shape designed to have an angle in at least one of the main direction and the width direction, the angle in the width direction of the pitch block is chamfered and the angle in the main direction of the large pitch is chamfered. Featuring pneumatic tires.

10. The method of item 9, wherein the width direction angle of the large pitch is smaller than the width direction angle of the pitch, and the main direction angle of the pitch is smaller than the main angle of the large pitch. Pneumatic Tire

11. The air tire according to 9 or 10, wherein a medium pitch is provided between the large pitch and the small pitch.

This aims to suppress the change of the grounding characteristic accompanying the change in the size of the block in one revolution of the tire and to improve the steering stability and uniformity (so-called uniformity).

This makes it possible to substantially match the grounding characteristic level during tire rotation due to the difference in block size. Specifically, the block stiffness can be set at the same level, and the deformation and force generation of the block can be approached in the same direction for each pitch.

As described above, the pneumatic tire design method according to the present invention is suitable for use in tire design of a pitch array composed of a plurality of pitches, and particularly, it is possible to achieve rigidity and uniformity (so-called uniformity) that are assumed to be due to shape mismatch. Suitable for use in homogenizing designs.

Claims (7)

(a) a plurality of shapes representing a selected one of a shape of a block unit including an internal structure, a pattern shape of a part of the tire crown portion including an internal structure, and a shape of a land portion continuous in the circumferential direction of the tire including the internal structure; Tire basic model having different basic shape models, objective function indicating physical quantity for tire performance evaluation, design variables that determine the shape or pattern of block unit or shape of flesh, shape of block unit, pattern shape and shape of meat Determining a constraint that constrains at least one of the selected one shape, tire cross-sectional shape, and physical quantity for tire performance evaluation; (b) calculating the value of the design variable by calculating while changing the value of the design variable until the optimum value of the objective function is given while considering the constraints; And and (c) designing a tire based on a design variable that gives an optimal value of the objective function. The method of claim 1, wherein the design variable is to determine the shape, pattern, or shape of another block unit body using at least one of the different shape basic models as a basic shape model. . The method of claim 1, wherein the design variable is used to determine the shape, pattern, or shape of the block unit body based on the predetermined shape basic model as a reference model. The method according to any one of claims 1 to 3, wherein in step (b), the change ratio of the sensitivity of the target function to the unit change amount of the design variable and the change ratio of the constraint on the unit change amount of the design variable The objective function value and design variable when the design variable is changed by an amount corresponding to the predicted amount while predicting the variation of the design variable that gives the optimal value of the objective function while considering the constraint based on the sensitivity of the A method of designing a pneumatic tire that calculates the value of a constraint when the value is changed by an amount corresponding to the predicted amount, and obtains the value of a design variable that gives the optimum value of the objective function while considering the constraint based on the predicted value and the calculated value. According to claim 1, wherein the step (a) is continuous in the circumferential direction of the tire including the shape of the block unit including the internal structure, the pattern shape of a portion of the tire crown including the internal structure and the internal structure A selection target group including a plurality of tire basic models having different shape basic models of voxes representing a selected one of the shapes of the flesh is defined, and the objective function and the design variable for each tire basic model of the selection target group. And an adaptation function that can be evaluated by the constraint and the objective function and the constraint. In step (b), two tire basic models are selected from the selection target group based on the adaptation function, and each tire has a predetermined probability. Creating a new tire base model by intersecting design variables of the base model and at least one side of the tire base model Do at least one of creating a new tire basic model by changing some of the design variables, and obtain the objective function, constraints and adaptation functions of the tire basic model with the changed design variables, and do not change the tire basic model and design variables. The tire basic model which is not stored is stored, and the stored tire basic model is repeated until the predetermined number is reached, and it is determined whether a new group consisting of the predetermined number of stored tire basic models satisfies the predetermined procedure conditions and does not satisfy the procedure conditions. If not, the new group is repeated as the selection group until the selection group satisfies a predetermined procedure condition while considering constraints from a predetermined number of tire basic models stored when the predetermined procedure condition is satisfied. Pneumatic tire design to find the value of design variable giving optimal value of objective function Law. The tire according to any one of claims 1 to 3, wherein the design variable is an angle of a surface connected to a surface of a tire flesh to be formed in a shape selected from a shape of a block unit, a pattern shape, and a shape of a meat part. A variable representing at least one of the height to the surface of the flesh, the surface shape of the tire meat, the surface shape connected to the surface of the tire meat, and the sipe shape of the position, number, width, depth, inclination, shape and length of the sipe. Air tire design method comprising. 4. The pneumatic tire design method according to any one of claims 1 to 3, wherein each of the tire basic models having a plurality of the shape basic models has a different length in the circumferential direction of the tire.