JP6349951B2 - Tire wear prediction method and wear prediction computer program - Google Patents

Description

  The present invention relates to a tire wear prediction method and a wear prediction computer program.

  In tire development, for example, tire wear is predicted as disclosed in the following patent document.

Japanese Patent Publication No. 06-063933 JP-A-11-326143 JP 2007-139708 A JP2013-226975A

  However, predicting tire wear using conventional techniques can be labor intensive. Therefore, it is desired to devise a technique that can suppress an increase in labor in predicting tire wear.

  An object of the present invention is to provide a tire wear prediction method and a wear prediction computer program that can suppress an increase in labor.

  In order to solve the above-described problems and achieve the object, the tire wear prediction method according to the present invention creates an approximate model including a contact area defined by a specified shape for a contact surface of the tire with respect to a road surface. , A procedure for setting a first approximation function relating to the shear stress in the slip region of the ground contact surface, a procedure for setting a second approximation function relating to the slip amount of the slip region of the ground contact surface, and an action on the tire A procedure for obtaining a resultant force of a longitudinal force and a lateral force, a procedure for obtaining a slip ratio and a slip angle when the longitudinal force and the lateral force act on the tire, and the first approximate function and the resultant force. A procedure for obtaining an average shear stress in the slip region, and a procedure for obtaining a slip amount in the slip region based on the second approximate function, the slip ratio, and the slip angle; On the basis of the average shear stress and to said slip amount includes a step of obtaining the friction energy in the ground plane, on the basis of the friction energy obtained, the procedure for predicting the wear of the tire, the.

  According to the present invention, an approximate model is created for the ground contact surface of the tire, and a first approximate function related to shear stress and a second approximate function related to slip amount are set, and the longitudinal force and lateral force acting on the tire are And the slip ratio and the slip angle when the longitudinal force and lateral force are applied, the average shear stress of the slip region is obtained based on the first approximate function and the resultant force, and the second approximate function By obtaining the slip amount based on the slip ratio and the slip angle, it is possible to easily predict tire wear (amount of wear). That is, there is a correlation between tire wear and frictional energy. When the friction energy is large, the tire wear increases, and when the friction energy is small, the tire wear decreases. Therefore, tire wear can be predicted by obtaining the friction energy. Friction energy is defined as the product of the shear force (shear stress) acting on the tire contact surface and the slip amount (friction energy = shear force × slip amount). Therefore, if the shearing force and the slip amount can be easily obtained, the friction energy can be easily obtained. According to the present invention, an approximate model that is modeled using a specified predetermined shape is created for the contact surface of the tire. The frictional energy in the approximate model can be easily and accurately obtained using the first approximate function, the second approximate function, the resultant force, the slip rate, and the slip angle. That is, the average shear stress and the slip amount can be easily obtained simply by inputting parameters relating to the tire characteristics with respect to the first approximate function and the second approximate function. By considering the resultant force, slip ratio, and slip angle in the combined conditions in which the longitudinal force and lateral force act on the tire, it is possible to accurately determine the friction energy and predict the tire wear with high accuracy. .

  In the tire wear prediction method according to the present invention, the predetermined shape may include a rectangle.

  In the tire wear prediction method according to the present invention, the average shear stress in the slip region includes an average shear stress in the front-rear direction and an average shear stress in the lateral direction, and the slip amount in the slip region is in the front-rear direction. Including the amount of slip and the amount of slip in the lateral direction, the procedure for obtaining the friction energy is to obtain the friction energy in the front-rear direction based on the average shear stress in the front-rear direction and the amount of slip in the front-rear direction; And determining the transverse friction energy based on the transverse average shear stress and the transverse slip amount.

  In the tire wear prediction method according to the present invention, a procedure for setting an approximate function of braking / driving stiffness when a lateral force is applied to the tire, and an approximate function of a turning stiffness when a longitudinal force is applied to the tire are set. The slip ratio is determined based on the approximate function of the braking / driving stiffness and the lateral force and the longitudinal force acting on the tire, and the slip angle is an approximate function of the turning stiffness. Further, it may be determined based on the longitudinal force and lateral force acting on the tire.

  In the tire wear prediction method according to the present invention, a procedure for setting an approximate function of the slip ratio when a longitudinal force and a lateral force act on the tire, and a case where the longitudinal force and the lateral force act on the tire A slip angle approximation function, and the slip ratio is determined based on the slip ratio approximation function and the longitudinal force and lateral force acting on the tire. You may obtain | require based on the approximate function of a slip angle, and the longitudinal force and lateral force which act on the said tire.

  In the tire wear prediction method according to the present invention, a procedure for setting a two-dimensional frequency distribution of longitudinal force and lateral force acting on the tire based on the running conditions of the tire including driving, braking, and turning, At each level of the two-dimensional frequency distribution, a procedure for obtaining an average shear stress in the slip region based on the longitudinal force and lateral force associated with the level and the first approximate function, and the longitudinal force associated with the level And a step of obtaining a slip amount of a slip region based on the lateral force and the second approximate function, a step of obtaining the friction energy based on the average shear stress and the slip amount, and the friction energy, A procedure for obtaining a frequency average friction energy based on an integrated value with a frequency and a procedure for predicting the wear of the tire based on the frequency average friction energy may be included.

  In the tire wear prediction method according to the present invention, a procedure for setting a two-dimensional frequency distribution of longitudinal acceleration and lateral acceleration acting on the vehicle based on a running condition of the vehicle on which the tire is mounted, and the two-dimensional frequency A procedure for associating a lateral force and a longitudinal force acting on the tire with each level of the distribution, and a longitudinal force and a lateral force associated with the level and the first approximate function at each level of the two-dimensional frequency distribution; A step of obtaining an average shear stress in the slip region, a step of obtaining a slip amount in the slip region based on the longitudinal force and lateral force associated with the level and the second approximate function, and the average shear A procedure for obtaining the friction energy based on the stress and the amount of slip, a procedure for obtaining a frequency average friction energy based on an integrated value of the friction energy and the frequency, and the frequency average Based on the friction energy, and procedures for predicting the wear of the tire may contain.

  In the tire wear prediction method according to the present invention, a procedure for setting an initial load acting on the tire, a procedure for setting a first load correction function and a second load correction function related to the friction energy, and the tire A procedure for associating a load acting on the tire with each level of a two-dimensional frequency distribution of acting longitudinal force and lateral force, or a two-dimensional frequency distribution of longitudinal acceleration and lateral acceleration acting on the vehicle, and the two-dimensional frequency A procedure for setting tire characteristic parameters of the first approximate function and the second approximate function based on the initial load at each level of the distribution, and the first approximate function based on the tire characteristic parameter And the second approximate function, the longitudinal force and lateral force associated with the level, and the first approximate function, the average shear response of the slip region On the basis of the longitudinal force and lateral force associated with the level and the second approximate function, the procedure for obtaining the slip amount of the slip region, the average shear stress and the slip amount, A procedure for obtaining friction energy, a procedure for obtaining a first load correction friction energy associated with the longitudinal force and the lateral force based on the load acting on the tire when the vehicle is stationary and the first load correction function; Correcting the first load correction friction energy based on the load acting on the tire when the vehicle travels and the second load correction function to obtain a second load correction friction energy; A procedure for obtaining a frequency average friction energy based on the integrated value of the load correction friction energy and the frequency of 2, a procedure for predicting tire wear based on the frequency average friction energy, It may also include a.

  In the tire wear prediction method according to the present invention, the first load correction function is a function relating to a condition in which a longitudinal force and a lateral force acting on the tire change in proportion to a change in the load, The load correction function may be a function related to a condition in which the longitudinal force and the lateral force are constant regardless of the change in the load.

  In the tire wear prediction method according to the present invention, a procedure for setting tire characteristic parameters of the first approximate function and the second approximate function as a function having a load as a variable, a longitudinal force acting on the tire, A procedure for associating a load acting on the tire with each level of a two-dimensional frequency distribution of lateral force, or a two-dimensional frequency distribution of longitudinal acceleration and lateral acceleration acting on a vehicle, and each level of the two-dimensional frequency distribution, Based on the load associated with the level, tire characteristic parameters of the first approximate function and the second approximate function are determined, and based on the tire characteristic parameter, the first approximate function and the second approximate function are determined. A procedure for setting an approximate function of the above, a procedure for obtaining an average shear stress in the sliding region based on the longitudinal force and lateral force and the first approximate function, a longitudinal force and lateral force, and the second Based on an approximate function, a procedure for obtaining a slip amount in a slip region, a procedure for obtaining the friction energy based on the average shear stress and the slip amount, and an integrated value of the friction energy and frequency. A procedure for obtaining frequency average friction energy and a procedure for predicting wear of the tire based on the frequency average friction energy may be included.

  In the tire wear prediction method according to the present invention, a procedure for obtaining a wear amount of the tread rubber based on a wear amount per unit friction energy of the tread rubber of the tire and the obtained friction energy, and the tread rubber And a procedure for predicting the wear of the tire based on the wear amount of the tire.

  In the tire wear prediction method according to the present invention, the tread rubber per unit travel distance is based on the tire radius, the wear amount per unit friction energy of the tread rubber of the tire, and the obtained friction energy. And a procedure for predicting the wear of the tire based on the wear amount of the tread rubber.

  In the tire wear prediction method according to the present invention, a procedure for predicting tire wear for each of a right wheel and a left wheel of a vehicle to which the tire is mounted, and an average wear of the right wheel wear and the left wheel wear And a procedure for predicting.

  In the tire wear prediction method according to the present invention, a procedure for predicting wear of the tire for each of a front wheel and a rear wheel of a vehicle on which the tire is mounted, and an average wear of the front wheel wear and the rear wheel wear And a procedure for predicting one or both of the wear ratio between the wear of the front wheel and the wear of the rear wheel.

  In order to solve the above-mentioned problems and achieve the object, a computer program for tire wear prediction according to the present invention causes a computer to execute the tire wear prediction method.

  According to the present invention, it is possible to predict tire wear while suppressing an increase in labor.

FIG. 1 is a cross-sectional view showing an example of a tire according to the first embodiment. FIG. 2 is a diagram illustrating an example of a processing apparatus capable of executing the tire wear prediction method according to the first embodiment. FIG. 3 is a flowchart illustrating an example of a procedure of the tire wear prediction method according to the first embodiment. FIG. 4 is a diagram illustrating an example of a ground contact surface of the tire according to the first embodiment. FIG. 5 is a diagram illustrating an example of the approximate model according to the first embodiment. FIG. 6 is a diagram for explaining the adhesion area and the sliding area of the ground plane. FIG. 7 is a conceptual diagram of a shear stress distribution approximated by a linear function. FIG. 8 is an explanatory diagram of the adhesion area and the sliding area of the ground plane. FIG. 9 is an explanatory diagram of the adhesion area and the sliding area of the ground plane. FIG. 10 is a diagram illustrating an example of the approximate model according to the second embodiment. FIG. 11 is a diagram illustrating an example of the approximate model according to the second embodiment. FIG. 12 is a diagram illustrating an example of the approximate model according to the second embodiment. FIG. 13 is a diagram illustrating an example of the approximate model according to the second embodiment. FIG. 14 is a diagram illustrating an example of the approximate model according to the second embodiment. FIG. 15 is a diagram illustrating an example of the approximate model according to the third embodiment. FIG. 16 is a diagram illustrating an example of the approximate model according to the third embodiment. FIG. 17 is a diagram illustrating an example of the approximate model according to the fourth embodiment. FIG. 18 is a diagram illustrating an example of the approximate model according to the fourth embodiment. FIG. 19 is a diagram illustrating an example of a ground contact surface of the tire according to the fifth embodiment. FIG. 20 is a diagram illustrating an example of the approximate model according to the fifth embodiment. FIG. 21 is a diagram illustrating an example of the approximate model according to the fifth embodiment. FIG. 22 is a diagram illustrating an example of a ground contact surface of the tire according to the fifth embodiment. FIG. 23 is a diagram illustrating an example of the approximate model according to the fifth embodiment. FIG. 24 is a diagram illustrating an example of the approximate model according to the fifth embodiment. FIG. 25 is a flowchart illustrating an example of a procedure of a tire wear prediction method according to the sixth embodiment. FIG. 26 is a flowchart illustrating an example of a procedure of a tire wear prediction method according to the seventh embodiment. FIG. 27 is a flowchart illustrating an example of a procedure of a tire wear prediction method according to the eighth embodiment. FIG. 28 is a flowchart illustrating an example of a procedure of a tire wear prediction method according to the ninth embodiment. FIG. 29 is a flowchart illustrating an example of a procedure of a tire wear prediction method according to the tenth embodiment. FIG. 30 is an explanatory diagram of the relationship between the tire radius and the amount of wear according to the thirteenth embodiment. FIG. 31 is a diagram showing the results for the comparative example. FIG. 32 is a diagram showing the results of the example according to the present invention.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of the embodiments described below can be combined as appropriate. Some components may not be used. In addition, constituent elements in the embodiments described below include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range.

  In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each part will be described with reference to this XYZ orthogonal coordinate system. One direction in the horizontal plane is defined as the X-axis direction, a direction orthogonal to the X-axis direction in the horizontal plane is defined as the Y-axis direction, and a direction orthogonal to each of the X-axis direction and the Y-axis direction is defined as the Z-axis direction. Further, the rotation (inclination) directions around the X axis, Y axis, and Z axis are the θX, θY, and θZ directions, respectively. In the present embodiment, the rotation axis of the tire 1 and the Y axis are parallel. The Y-axis direction is the vehicle width direction or the width direction of the tire 1. The rotation direction (corresponding to the θY direction) of the tire 1 (the rotation axis of the tire 1) may be referred to as a circumferential direction. The X-axis direction and the Z-axis direction are radial directions with respect to the rotation axis. The radial direction with respect to the rotation axis may be referred to as a radial direction. The road surface on which the tire 1 rolls (runs) is substantially parallel to the XY plane.

<First Embodiment>
A first embodiment will be described. FIG. 1 is a cross-sectional view showing an example of a tire 1 according to this embodiment. FIG. 1 shows a meridional section through the rotation axis of the tire 1. The tire 1 includes a carcass 2, a belt layer 3, a belt cover 4, a bead core 5, a tread rubber 6, and a sidewall rubber 7. Each of the carcass 2, the belt layer 3, and the belt cover 4 includes a cord. The cord is a reinforcing material. The cord may be referred to as a wire. Each layer (part) including a cord (reinforcing material) such as the carcass 2, the belt layer 3, and the belt cover 4 may be referred to as a cord layer or a reinforcing material layer.

  The carcass 2 is a member (strength member) that forms the skeleton of the tire 1. The carcass 2 includes a cord (reinforcing material). The carcass 2 cord may be referred to as a carcass cord. The carcass 2 is a cord layer (reinforcing material layer) including cords. The carcass 2 functions as a pressure vessel when the tire 1 is filled with air. The carcass 2 is supported by the bead core 5. The bead cores 5 are arranged on one side and the other side of the carcass 2 with respect to the Y-axis direction. The carcass 2 is folded back at the bead core 5. The carcass 2 includes an organic fiber cord (carcass cord) and rubber covering the cord. The rubber covering the cord may be referred to as coat rubber or topping rubber. The carcass 2 may include a polyester cord, a nylon cord, an aramid cord, or a rayon cord.

  The belt layer 3 is a member (strength member) that holds the shape of the tire 1. The belt layer 3 includes a cord (reinforcing material). The cord of the belt layer 3 may be referred to as a belt cord. The belt layer 3 is a cord layer (reinforcing material layer) including a cord. The belt layer 3 is disposed between the carcass 2 and the tread rubber 6. The belt layer 3 includes, for example, a metal fiber cord (belt cord) such as steel and rubber (coat rubber, topping rubber) covering the cord. The belt layer 3 may include an organic fiber cord. In the present embodiment, the belt layer 3 includes a first belt ply 3A and a second belt ply 3B. The first belt ply 3A and the second belt ply 3B are laminated so that the cord of the first belt ply 3A and the cord of the second belt ply 3B intersect.

  The belt cover 4 is a member (strength member) that protects and reinforces the belt layer 3. The belt cover 4 includes a cord (reinforcing material). The cord of the belt cover 4 may be referred to as a cover cord. The belt cover 4 is a cord layer (reinforcing material layer) including a cord. The belt cover 4 is disposed outside the belt layer 3 (on the grounding surface side) with respect to the rotation axis of the tire 1. The belt cover 4 includes, for example, a metal fiber cord (cover cord) such as steel and rubber (coat rubber, topping rubber) covering the cord. The belt cover 4 may include an organic fiber cord.

  The bead core 5 is a member (strength member) that fixes both ends of the carcass 2. The bead core 5 fixes the tire 1 to the rim. The bead core 5 is a bundle of steel wires. The bead core 5 may be a bundle of carbon steel.

  The tread rubber 6 protects the carcass 2. The tread rubber 6 includes a ground contact surface (tread portion) 10 that contacts a road surface (ground), and a first groove 21 and a second groove 22. The ground plane 10 is disposed at least partly around the first groove 21 and the second groove 22. The inner surface of the first groove 21 and the inner surface of the second groove 22 do not contact the road surface (ground). Each of the first groove 21 and the second groove 22 is a non-ground portion. When rolling on a road surface on which the tire 1 is wet, such as in rainy weather, the first groove 21 and the second groove 22 can exclude water from between the tire 1 and the road surface.

  The side wall rubber 7 protects the carcass 2. The sidewall rubber 7 is disposed on each of one side and the other side of the tread rubber 6 with respect to the Y-axis direction. The side wall rubber 7 has a side wall portion 71.

  FIG. 2 is a diagram illustrating an example of a processing device 50 that performs simulation (computer analysis) and evaluation of characteristics (performance and behavior) of the tire 1 according to the present embodiment. The processing device 50 includes a computer (computer system). In the present embodiment, simulation and evaluation of the characteristics (performance and behavior) of the tire 1 are performed using the processing device 50 including a computer. In the present embodiment, the processing device 50 including a computer predicts and evaluates wear (wear characteristics) of the tire 1 using input information (such as parameters).

  The processing device 50 can create an analysis model (tire model) of the tire 1 to be evaluated. That is, the processing device 50 can create an analysis model that can be analyzed by a computer. In the present embodiment, the processing device 50 can create an approximate model of the contact surface 10 of the tire 1 with respect to the road surface as an analysis model.

  The processing device 50 can simulate (analyze) the characteristics of the tire 1 from the created analysis model. The processing device 50 can predict the wear (wear characteristics) of the tire 1 from the created analysis model, and can evaluate the wear characteristics of the tire 1 from the prediction result. In the present embodiment, the processing device 50 may be referred to as a model creation device 50, a simulation device 50, an analysis device 50, or an evaluation device 50. May be referred to as the wear prediction device 50.

  In the present embodiment, the processing device 50 includes a processing unit 50p, a storage unit 50m, and an input / output unit 59. The processing unit 50p and the storage unit 50m are connected via the input / output unit 59.

  The processing unit 50p includes a CPU (Central Processing Unit) and a memory such as a RAM (Random Access Memory). The processing unit 50p can execute a model creation unit 51 that can create an analysis model of the tire 1 (approximate model of the contact surface 10), simulation (analysis) of the characteristics of the tire 1, and evaluation of a simulation result (analysis result). And an analysis unit 52. The model creation unit 51 and the analysis unit 52 are each connected to an input / output unit 59. The model creation unit 51 and the analysis unit 52 can communicate data with each other via the input / output unit 59.

  The model creation unit 51 can create an analysis model of the tire 1. The model creation unit 51 can create an approximate model of the ground contact surface 10 of the tire 1. The model creation unit 51 can create an approximate model using a predetermined shape specified in advance for the ground contact surface 10 of the tire 1 with respect to the road surface. The analysis unit 52 simulates (predicts) the wear of the tire 1 from the approximate model (analysis model) created by the model creation unit 51 according to the procedure according to the present embodiment. From the analysis result by the analysis unit 52, the performance of the tire 1 is evaluated.

  The storage unit 50m includes at least one of a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory, a fixed disk device such as a hard disk device, and a storage device such as a flexible disk and an optical disk.

  The storage unit 50m stores at least a part of first information for creating an analysis model (approximate model) and second information for simulation (analysis and prediction).

  The first information for creating the analysis model includes information on a predetermined shape designated in advance in order to create an approximate model of the ground plane 10. The predetermined shape may be at least one of a polygon, a circle, an oval, and an ellipse. The predetermined shape may be at least one of a rectangle, a trapezoid, a hexagon, and an octagon. The predetermined shape may be a shape obtained by cutting out a part of the above polygon, a shape obtained by cutting a part of a circle, a shape obtained by cutting a part of an oval, or a part of an ellipse. A cut shape may be used. The predetermined shape may be a combination of the above shapes. The area having the predetermined shape is a closed area. The first information includes information related to the contact surface 10 of the tire 1. The information regarding the grounding surface 10 of the tire 1 includes at least one of the shape of the grounding surface 10, the area of the grounding surface 10, the grounding length, and the grounding width. In addition, the information regarding the predetermined shape and the information regarding the ground contact surface 10 of the tire 1 may be included in the second information.

  The second information for simulation includes, for example, information on boundary conditions. The boundary conditions are conditions necessary for simulation (analysis) of the analysis model, and include various conditions given to the analysis model. The boundary condition includes, for example, the traveling condition of the tire 1. In the present embodiment, the second information includes information related to the traveling conditions of the tire 1, the force generated in the tire 1 when the tire 1 travels (rolls), and the stiffness (rigidity) of the tire 1. The traveling condition of the tire 1 includes at least one of driving, braking, and turning (one or both of right turning and left turning). The force generated in the tire 1 during running (rolling) includes at least one of a driving force, a braking force, and a turning force (one or both of a right turning force and a left turning force). Further, the force generated in the tire 1 includes one or both of a longitudinal force and a lateral force. The stiffness of the tire 1 includes at least one of driving stiffness, braking stiffness, and turning stiffness. The second information includes various conditions such as the acceleration of the tire 1, the load on the tire 1, and the frictional force between the tire 1 and the ground.

  The storage unit 50m stores a first program (first computer program) for creating an analysis model (approximate model). The storage unit 50m stores a second program (second computer program) for simulating (analyzing) the characteristics of the tire 1. The second program includes a program for predicting the wear of the tire 1. The storage unit 50m stores a third program (third computer program) for evaluating the characteristics of the tire 1. The first program can cause the processing device (computer) 50 to execute the approximate model creation method according to the present embodiment. The second program can cause the processing device (computer) 50 to execute the simulation method (the tire 1 wear prediction method) according to the present embodiment. The third program can cause the processing device (computer) 50 to execute the evaluation method according to the present embodiment. The first program may be referred to as an analysis model creation program. The second program may be referred to as a simulation program, an analysis program, or a tire 1 wear prediction program. The third program may be referred to as an evaluation program. One program may cause the processing device (computer) 50 to execute analysis model creation, simulation (wear prediction), and evaluation.

  The model creation unit 51 can create an analysis model of the tire 1 (approximate model of the contact surface 10) based on the first information for creating the analysis model and the first program. The analysis unit 52 can execute simulation (analysis and prediction) of the characteristics (wear) of the tire 1 based on the second information for simulation (analysis) and the second program. The analysis unit 52 can execute the evaluation of the tire 1 based on the third program. For example, when the analysis unit 52 executes the simulation of the tire 1, the second program and the second information (the tire 1 conditions, boundary conditions, and the like) are read into the memory included in the analysis unit 52. The analysis unit 52 performs arithmetic processing based on the second program and the second information. A numerical value in the middle of calculation by the analysis unit 52 is appropriately stored in at least one of the memory included in the analysis unit 52 and the storage unit 50m. The stored numerical value is appropriately extracted from at least one of the memory included in the analysis unit 52 and the storage unit 50m, and the analysis unit 52 performs arithmetic processing using the extracted numerical value.

  The input / output unit 59 is connected to the terminal device 60. The terminal device 60 is connected to the input device 61 and the output device 62. The input device 61 includes at least one of a keyboard, a mouse, and a microphone. The output device 62 includes at least one of a display device such as a display and a printer.

  At least one of first information for creating an analysis model and second information for simulation (analysis and prediction) may be input from the input device 61. At least one of the first program that can execute the analysis model creation method according to the present embodiment, the second program that can execute the simulation method (wear prediction method), and the third program that can execute the evaluation method is the input device 61. May be input. Note that one program that can cause the processing device (computer) 50 to execute analysis model creation, simulation (wear prediction), and evaluation may be input from the input device 61.

  Information (program) input from the input device 61 may be sent to at least one of the processing unit 50p and the storage unit 50m via the terminal device 60 and the input / output unit 59. Based on information from the input device 61, the processing unit 50p can execute at least one of creation of an analysis model, simulation, analysis, and evaluation. The storage unit 50m can store information from the input device 61.

  In the present embodiment, the program is not limited to a single program. In the present embodiment, the functions of the program may be achieved together with a program that is already stored in the computer system. The program already stored in the computer system includes a separate program represented by an OS (Operating System), for example.

  A program (at least one of the first, second, and third programs) for realizing the function of the processing unit 50p (at least one of the analysis model creation function, the simulation function, and the evaluation function) is computer-readable. When the program recorded in the recording medium is read into the computer system, the computer system executes at least one of creation of an analysis model, simulation (analysis, prediction), and evaluation. Also good. The computer system includes the processing device 50 and includes the above-described OS and hardware such as peripheral devices.

  The processing unit 50p uses both the information (program) from the storage unit 50m and the information (program) from the input device 61 to create an analysis model (approximate model), simulate (analyze, predict), And at least one of the evaluations may be performed. Note that the processing unit 50p creates an analysis model using at least two of information (program) from the storage unit 50m, information (program) from the input device 61, and information (program) from the recording medium. At least one of simulation (analysis and prediction) and evaluation may be executed.

  Data from the processing unit 50p including at least one of the analysis model (approximate model) created by the model creation unit 51 and the analysis result (prediction result) of the analysis unit 52 is transmitted via the input / output unit 59 and the terminal device 60. Are sent to the output device 62. The output device 62 can output the data. When the output device 62 includes a display device, the display device can display data from the processing unit 50p.

  In the present embodiment, the storage unit 50m may be built in the processing unit 50p. The storage unit 50m may be included in a device (for example, a database server) different from the processing device 50. The terminal device 60 may access the processing device 50 by at least one of a wired method and a wireless method.

  Next, an example of a method for predicting wear of the tire 1 according to the present embodiment will be described. FIG. 3 is a flowchart showing a processing procedure of the method for predicting wear of the tire 1 according to the present embodiment. As shown in FIG. 3, the method for predicting wear of the tire 1 according to the present embodiment relates to a procedure (step SA1) for creating an approximate model of the ground contact surface 10 of the tire 1 that can be analyzed by a computer, and shear stress of the tire 1. A procedure for setting an approximate function (step SA2), a procedure for setting an approximate function related to the slip amount of the tire 1 (step SA3), a procedure for setting a longitudinal force and a lateral force acting on the tire 1 (step SA4), A procedure for obtaining the resultant force of the longitudinal force and the lateral force acting on the tire 1 (step SA5), a procedure for obtaining a slip ratio when the longitudinal force and the lateral force act on the tire 1 (step SA6), and a longitudinal force on the tire 1 A procedure for obtaining a slip angle when a force and a lateral force are applied (step SA7), a procedure for calculating an average shear stress of the tire 1 (step SA8), a tie It includes a procedure (step SA9) for calculating a slip amount of 1, and the procedure (step SA10) of calculating a friction energy of the tire 1, the procedure for predicting the wear of the tire 1 (step SA12), the.

  FIG. 4 is a diagram illustrating an example of the ground contact surface 10 of the tire 1 with respect to the road surface. As shown in FIG. 4, the tire 1 includes a ground contact surface (tread portion) 10 that contacts the road surface, and a first groove 21 and a second groove 22. In the present embodiment, the ground contact surface 10 has a center region 11 and one side (+ Y side) and the other side of the center region 11 with respect to the Y-axis direction (the width direction of the tire 1 and the direction parallel to the rotation axis of the tire 1). -Y side) and a shoulder region 12 disposed on each.

  The first groove 21 is formed in the circumferential direction of the tire 1. At least a part of the second groove 22 is formed in the width direction of the tire 1. The first groove 21 may be referred to as the main groove 21. The second groove 22 may be referred to as a lug groove 22. In the example shown in FIG. 4, the tire 1 has four (four) first grooves 21. The ground plane 10 includes five areas 101, 102, 103, 104, and 105 arranged in the Y-axis direction. The first grooves 21 are disposed between the region 101 and the region 102, between the region 102 and the region 103, between the region 103 and the region 104, and between the region 104 and the region 105, respectively. That is, the ground plane 10 is divided into five regions 101, 102, 103, 104, and 105 in the Y-axis direction by the four first grooves 21. Of the five areas 101, 102, 103, 104, and 105 arranged in the Y-axis direction, the area 101 is arranged closest to the −Y side, and the area 102 is next to the area 101 on the −Y side. The area 103 is arranged on the −Y side next to the area 102, the area 104 is arranged on the −Y side next to the area 103, and the area 105 is arranged on the most + Y side. The center area 11 includes an area 102, an area 103, and an area 104. The shoulder region 12 includes a region 101 and a region 105. The second groove 22 is disposed in each of the region 101, the region 102, the region 103, the region 104, and the region 105.

  The model creation unit 51 creates the approximate model 30 of the ground plane 10 shown in FIG. 4 (Step SA1). First information for creating the approximate model 30 is input to the model creating unit 51. The first information includes information related to a predetermined shape for creating the approximate model 30 of the ground plane 10. The predetermined shape is a shape designated in advance for creating the approximate model 30. Information relating to the predetermined shape is input to the model creation unit 51.

  The predetermined shape may be at least one of a polygon, a circle, an oval, and an ellipse. The predetermined shape may be at least one of a rectangle, a trapezoid, a hexagon, and an octagon. The predetermined shape may be a shape obtained by cutting out a part of the above polygon, a shape obtained by cutting a part of a circle, a shape obtained by cutting a part of an oval, or a part of an ellipse. A cut shape may be used. The predetermined shape may be a combination of the above shapes. The area having the predetermined shape is a closed area. In the present embodiment, a rectangle (rectangle) is used as the predetermined shape.

  FIG. 5 is a diagram illustrating an example of the approximate model 30 of the ground plane 10 created using a rectangle (rectangle). In the present embodiment, the model creation unit 51 creates the approximate model 30 for each of the center region 11 and the shoulder region 12 of the ground plane 10. The approximate model 30 includes a center model region 31 that models the center region 11 and a shoulder model region 32 that models the shoulder region 12.

  In the present embodiment, the center model region 31 is defined by one rectangle. In other words, the center model region 31 is modeled without considering the first groove 21. The center model region 31 is created with the first groove 21 as a grounding region. That is, in the approximate model 30, the first groove 21 is treated as a ground contact portion that contacts the road surface. In other words, the center model region 31 is obtained by modeling each of the region 102, the region 103, the region 104, and the first groove 21 adjacent to the region 102 of the tire 1 as a ground contact region. In the example shown in FIG. 5, the computational effort is suppressed, and the wear of the tire 1 can be easily obtained.

As shown in FIG. 5, the dimensions of the center model region 31 in the Y-axis direction is W _c. The dimensions of the center model region 31 in the X-axis direction is _{L c.} The dimension of the shoulder model region 32 in the Y-axis direction is W _s . The dimensions of the shoulder model region 32 in the X-axis direction is _{L s.} The dimension L _c and the dimension L _s correspond to the contact length of the tire 1 (the dimension of the contact surface 10 with respect to the traveling direction).

  Next, the analysis unit 52 sets an approximate function related to shear stress (step SA2). The analysis unit 52 sets an approximate function of the shear stress distribution in the adhesion area and the slip area of the ground plane 10. The analysis unit 52 sets an approximate function of the shear stress distribution for each of the center model region 31 and the shoulder model region 32.

  FIG. 6 is a conceptual diagram of an adhesive area and a sliding area formed on the ground plane 10. In FIG. 6, the horizontal axis indicates the traveling direction of the vehicle (X-axis direction). The vertical axis represents the shear stress τ. In FIG. 6, line L1 is the maximum friction curve of the tire 1 (tread rubber 6), and is the product of the friction coefficient of the tire 1 (tread rubber 6) and the contact pressure distribution.

  The tread rubber 6 of the tire 1 starts to contact the road surface at the stepped-in end (beginning of ground contact) x0. The tread rubber 6 does not contact the road surface until just before the x0 point. Therefore, the tread rubber 6 is in close contact with the road surface at the point x0. After the x0 point, the tread rubber 6 (the ground contact surface 10) bends and bends on the road surface. That is, the tread rubber 6 is gradually subjected to shearing from the road surface in the movement from the stepping-in end x0 point to the kicking-out end (end of ground contact) x2. Thereby, a shearing force is generated in the tread rubber 6. Since the tread rubber 6 is bent, the contact between the tread rubber 6 and the road surface is maintained. Thus, a partial region of the ground contact surface 10 of the tread rubber 6 that is in close contact with the road surface by bending is referred to as an adhesive region.

  At the point x1 when the shear stress τ gradually increases and reaches the maximum friction curve L1, the ground contact surface 10 of the tread rubber 6 that is in close contact with the road surface slides with respect to the road surface. That is, when the shearing force reaches the maximum friction curve L1, the ground contact surface 10 cannot follow the road surface, and the ground contact surface 10 of the bent tread rubber 6 is deformed so that the flexure returns near the point x1. (Restoration) begins and the ground contact surface 10 slides with respect to the road surface. In this way, a partial region of the ground contact surface 10 of the tread rubber 6 that slides with respect to the road surface is referred to as a slip region.

  FIG. 7 is a conceptual diagram of shear stress (shear stress distribution) approximated by a linear function (linear expression). As shown in FIGS. 6 and 7, the shear stress τ in the traveling direction (X-axis direction) can be approximated by a linear function. That is, the approximate function τ (x) related to the shear stress (shear stress distribution) in the adhesive region can be expressed by a linear function as indicated by a line L2 in FIG. The approximate function τ (x) related to the shear stress (shear stress distribution) in the slip region can be expressed by a linear function as indicated by a line L3 in FIG. In other words, from the point x0 to the point x1, the distance x from the point x0 and the shear stress τ are proportional, and from the point x1 to the point x2, the distance x from the point x1 and the shear stress τ are proportional.

  In the present embodiment, the analysis unit 52 sets an approximate function of the shear stress distribution for each of the center model region 31 and the shoulder model region 32. In the present embodiment, the analysis unit 52 approximates the shear stress distribution in each of the center model region 31 and the shoulder model region 32 with a linear function.

  Equation (1) is an approximate equation for obtaining the average shear stress of the slip region in the center region 11 during turning. Expression (2) is an approximate expression for obtaining the average shear stress of the slip region in the center region 11 during braking / driving (driving and braking). Expression (3) is an approximate expression for obtaining the average shear stress in the slip region in the shoulder region 12 during turning. Expression (4) is an approximate expression for obtaining the average shear stress of the slip region in the shoulder region 12 during braking / driving.

In the present embodiment, with the resultant force F of the longitudinal force F _x and the lateral force F _y, the average shear stress of the sliding region is determined. That is, Formula (5), which is a generalization of Formula (1) and Formula (2), is an approximate formula (approximate function) for obtaining the average shear stress in the slip region in the center region 11. Formula (6), which is a generalization of Formula (3) and Formula (4), is an approximate formula (approximate function) for determining the average shear stress in the slip region in the shoulder region 12.

  Next, the analysis unit 52 sets an approximate function related to the slip amount (step SA3). The analysis unit 52 sets an approximate function of the slip amount of the ground contact surface 10 with respect to the road surface. The analysis unit 52 sets an approximate function of the slip amount in the slip region with respect to the road surface. The analysis unit 52 sets an approximate function of the slip amount for each of the center model region 31 and the shoulder model region 32.

  The approximate function of the slip amount includes the stiffness of the tire 1 as a parameter. In the present embodiment, the approximate function of the slip amount includes an approximate function of the slip amount during driving of the tire 1, an approximate function of the slip amount during braking, and an approximate function of the slip amount during turning. The stiffness of the tire 1 includes turning stiffness (lateral stiffness) and braking / driving stiffness (front-rear stiffness).

  FIG. 8 is a view of the ground contact surface 10 of the tire 1 having the slip angle α as viewed from above. The X axis is the traveling direction of the tire 1. The center line of the tire 1 (wheel) is inclined by α with respect to the X axis. The tire 1 is inclined in the direction of α with respect to the traveling direction (X axis) and rolls in the direction of the X axis as a whole. In the tire 1 (the ground contact surface 10) having the slip angle α, an adhesion region and a slip region are formed.

9, the difference between the rolling speed (tread base speed) V _B of the moving velocity V _R and the tire 1 of the road surface, the adhesive region and the sliding region in the braking and driving direction of the tire 1 (ground surface 10) (longitudinal direction) An example in which and are formed is shown.

  Expression (7) is an approximate expression for obtaining the slip amount of the slip area in the center area 11 at the time of turning. Expression (8) is an approximate expression for obtaining the slip amount of the slip region in the center region 11 during braking / driving. Equation (9) is an approximate equation for obtaining the slip amount of the slip region in the shoulder region 12 during turning. Expression (10) is an approximate expression for obtaining the slip amount of the slip region in the shoulder region 12 during braking / driving.

  An approximate expression (approximation function) of the slip amount in the lateral direction (during turning), which generalizes the expressions (7) and (9), is the expression (11). An approximate expression (approximate function) of the slip amount in the front-rear direction (during braking / driving), which is a generalization of Expressions (8) and (10), is Expression (12).

Note that the stiffness of the sidewall portion 71 (sidewall rubber 7) or the deformation of the sidewall portion 71 during turning may affect the slip amount during turning. Therefore, a correction coefficient R _s that takes into account the stiffness of the sidewall portion 71 may be set, and the slip amount may be corrected using the correction coefficient R _s as shown in the following equation (13). Note that the correction coefficient R _s may be obtained in advance by experiment, for example, or may be obtained in advance by simulation.

  In the present embodiment, the slip amount is obtained using the slip ratio SR and the slip angle α. In the present embodiment, the slip amount in the front-rear direction is obtained using the approximate expression (approximate function) shown in Expression (14). Using the approximate expression (approximation function) shown in Expression (15), the slip amount in the horizontal direction is obtained.

Next, the analysis unit 52 obtains the resultant force F of the longitudinal force _{F x} and the lateral force _{F y} acting on the tire 1 (step SA4). The resultant force F is obtained by the following equation (16).

Next, the analysis part 52 calculates | requires the slip ratio SR and slip angle (alpha) when the longitudinal force _Fx and the lateral force _Fy act on the tire 1 (step SA6, step SA7).

  The slip ratio SR is obtained by the following equation (17).

  Next, the analysis part 52 calculates | requires the average shear stress of a slip area based on the approximate function shown by (5) Formula and (6) Formula, and the resultant force F shown by (16) Formula (step SA8).

  The average shear stress in the sliding region in the center region 11 can be obtained by substituting the resultant force F of the equation (16) into the equation (5). The average shear stress of the slip region in the shoulder region 12 can be obtained by substituting the resultant force F of the equation (16) into the equation (6).

  Next, the analysis part 52 calculates | requires the slip amount of a slip area based on the approximation function shown by (14) Formula and (15) Formula, the slip ratio SR, and the slip angle (alpha) (step SA9).

  The slip amount in the front-rear direction can be obtained by substituting the slip ratio SR into the equation (14). The slip amount in the lateral direction can be obtained by substituting the slip angle α into the equation (15).

  Note that the amount of slip in the horizontal direction may be obtained based on the equation (11). The slip amount in the front-rear direction may be obtained based on the equation (12).

  Next, the analysis part 52 calculates | requires the friction energy in the contact surface 10 based on the average shear stress calculated | required by step SA8, and the slip amount calculated | required by step SA9 (step SA10).

Friction energy _{E x} in the longitudinal direction is determined from the following equation (18). The frictional energy E _{y in the} lateral direction is obtained from the following equation (19). Note that τ _x is a component before and after the average shear stress τ _c of the center region 11 shown by the equation (5) or the average shear stress τ _s of the shoulder region 12 shown by the equation (6). τ _y is a lateral component of the resultant force of the average shear stress τ _c of the center region 11 expressed by the equation (5) or the average shear stress τ _s of the shoulder region 12 expressed by the equation (6).

Analyzer 52 sums the friction energy E _y in the longitudinal direction of the friction energy E _x and lateral, obtains the frictional energy E when the longitudinal force F _x and the lateral force F _y is applied. The friction energy E is obtained from the following equation (20).

  Next, it is determined whether or not calculation of the friction energy has been completed for all of the center model region 31 and the shoulder model region 32 of the approximate model 30 (step SA11). If it is determined in step SA11 that the calculation of the friction energy for all the regions has not been completed (in the case of No), the process returns to step SA8, and it is determined that the calculation of the friction energy for all the regions has been completed. Until then, the same processing is performed.

  In step SA11, when it is determined that the calculation of the friction energy for each of the center model region 31 and the shoulder model region 32 has been completed (in the case of Yes), the analysis unit 52 determines the wear of the tire 1 (tread rubber 6). Prediction is made (step SA12). There is a correlation (for example, a proportional relationship) between the friction energy and the wear (wear amount) of the tire 1. Therefore, the analysis unit 52 can predict the wear (amount of wear) of the tire 1 based on the friction energy obtained in step SA10.

  In the present embodiment, the analysis unit 52 may predict the wear (wear amount) of the tire 1 in consideration of the material characteristics (wear resistance) of the tread rubber 6. In other words, the analysis unit 52 may predict the wear (amount of wear) of the tire 1 based on the frictional energy obtained in step SA10 and the material characteristics of the tread rubber 6. For example, the wear amount of the tread rubber 6 is obtained based on the wear amount per unit friction energy of the tread rubber 6 of the tire 1 and the friction energy obtained in step SA10, and based on the obtained wear amount of the tread rubber 6. Thus, wear of the tire 1 (tread rubber 6) may be predicted. As a result, wear prediction in consideration of the wear resistance of the tread rubber 6 becomes possible. The same applies to the embodiments described below.

  As described above, according to the present embodiment, the approximate model 30 is created for the ground contact surface 10 of the tire 1, the approximation function regarding the shear stress distribution in the slip region of the contact surface 10, and the approximation regarding the slip amount in the slip region. A function is set, and the average shear stress in the slip region is obtained based on the approximate function relating to the shear stress distribution, and the slip amount is obtained based on the approximate function relating to the slip amount, whereby the wear of the tire 1 (tread rubber 6) (wear) Quantity) can be easily predicted. As described above, there is a correlation between the wear amount of the tire 1 and the friction energy. That is, when the friction energy is large, the wear of the tire 1 increases, and when the friction energy is small, the wear of the tire 1 decreases. Further, a substantially proportional relationship is established between the friction energy and the wear amount of the tire 1. Therefore, the wear of the tire 1 can be predicted by obtaining the friction energy. The friction energy is defined as the product of the shearing force (shear stress) acting on the tire 1 and the slip amount (friction energy = shear force × slip amount). Therefore, if the shear stress and the slip amount can be easily obtained, the friction energy can be easily obtained. According to the present embodiment, the approximate model 30 that is modeled using the specified predetermined shape is created for the ground contact surface 10 of the tire 1. The frictional energy in the approximate model 30 can be easily obtained using an approximate function related to shear stress and an approximate function related to the slip amount. That is, the average shear stress and the slip amount can be easily obtained simply by inputting the parameters related to the characteristics of the tire 1 with respect to the approximate function related to the shear stress and the approximate function related to the slip amount. As a result, the friction energy can be easily obtained.

  Further, according to the present embodiment, the average shear stress is obtained based on the resultant force of the longitudinal force and the lateral force acting on the tire 1, and the slip amount based on the slip ratio and the slip angle when the longitudinal force and the lateral force are applied. Since the tire frictional energy characteristic under the combined condition in which the longitudinal force and the lateral force act on the tire 1 can be appropriately considered, the prediction accuracy can be improved.

  When only the longitudinal force is applied to the tire 1, the resultant force of the longitudinal force and the lateral force is obtained with the lateral force = 0, and the slip ratio and the slip angle when the resultant force of only the longitudinal force (lateral force = 0) is applied. You can ask for. Further, when only the lateral force acts on the tire 1, the resultant force of the longitudinal force and the lateral force is obtained by setting the longitudinal force = 0, and the slip ratio and the slip angle when the resultant force of only the lateral force (the longitudinal force = 0) is applied. You can ask for.

  Further, in the present embodiment, the ground contact surface 10 of the tire 1 is divided into the center region 11 and the shoulder region 12 with the first groove 21 as a boundary, and the approximate model 30 is divided into the center model region 31 and the shoulder model region 32. Divided. In this embodiment, for each of the plurality of regions (the center model region 31 and the shoulder model region 32), each of the average shear stress, the slip amount, and the friction energy can be easily obtained. Quantity) can be easily predicted.

  In the present embodiment, the predetermined shape used for the approximate model 30 is a rectangle (rectangular region). Therefore, an approximate function can be obtained easily, the calculation burden is reduced, and the friction energy can be easily obtained.

  In this embodiment, the approximation function of the shear stress distribution is a linear function. By making the approximate function of the shear stress distribution a linear function, it is possible to more easily predict the wear of the tire 1 while ensuring practical prediction accuracy.

  In this embodiment, the approximate function of the shear stress distribution may be a linear function, a quadratic function, a cubic function, a quartic function, a quintic function, It may be a 6th order function, a 7th order function, or an 8th order function. Moreover, the approximate function of the shear stress distribution may include an exponential function or an arbitrary function. For example, the shear stress distribution in the slip region may be approximated by a linear function corresponding to the straight line L3 shown in FIG. 6, or may be approximated by a function corresponding to the maximum friction curve L1. Further, the approximate function of the shear stress distribution is not limited to the first to eighth order functions and the exponential function, and may be an arbitrary function. The same applies to the following embodiments.

  Note that the approximate function of the average shear stress may be an n-order power function as shown in the equations (21) and (22).

Second Embodiment
A second embodiment will be described. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 10 is a diagram showing an example of the approximate model 30B of the ground plane 10 shown in FIG. As shown in FIG. 10, the approximate model 30B includes a center model region 31B that models the center region 11, and a shoulder model region 32B that models the shoulder region 12. In the present embodiment, the center model region 31B and the shoulder model region 32B include a plurality of regions 301, a region 302, a region 303, a region 304, and a region 305. The region 301, the region 302, the region 303, the region 304, and the region 305 are arranged in the Y axis direction. A region 301 is a region (ground region) in which the region 101 of the ground surface 10 is modeled. The region 302 is a region (ground region) where the region 102 of the ground surface 10 is modeled. A region 303 is a region (ground region) in which the region 103 of the ground surface 10 is modeled. A region 304 is a region (ground region) where the region 104 of the ground plane 10 is modeled. The region 305 is a region (ground region) where the region 105 of the ground surface 10 is modeled. Each of the region 301, the region 302, the region 303, the region 304, and the region 305 is defined by a rectangle (predetermined shape). That is, in this embodiment, the model creation unit 51 approximates the area 101 of the ground plane 10 with a rectangular area (ground area) 301, approximates the area 102 with a rectangular area (ground area) 302, and creates the area 103. The rectangular area (grounding area) 303 is approximated, the area 104 is approximated by a rectangular area (grounding area) 304, and the area 105 is approximated by a rectangular area (grounding area) 305.

  In the present embodiment, the model creation unit 51 creates the approximate model 30B in consideration of the first groove 21 that is a non-grounding part that does not contact the road surface. The model creation unit 51 approximates the first groove 21 in the region 211. The region 211 is a region where the first groove 21 is modeled. A region 211 is a non-grounding region that does not contact the road surface. The approximate model 30 </ b> B is created with the first groove 21 as a region (non-grounded region) 211. In the approximate model 30B, the region 211 is treated as a non-ground region (non-ground portion).

  A region 211 is arranged between the region 301 and the region 302, between the region 302 and the region 303, between the region 303 and the region 304, and between the region 304 and the region 305, respectively. That is, the approximate model 30B is divided into five regions 301, 302, 303, 304, and 305 in the Y-axis direction by the four regions 211. Of the five regions 301, 302, 303, 304, and 305 arranged in the Y-axis direction, the region 301 is arranged closest to the −Y side, and the region 302 is next to the region 301 on the −Y side. The region 303 is disposed on the −Y side next to the region 302, the region 304 is disposed on the −Y side next to the region 303, and the region 305 is disposed on the most + Y side. The center model region 31B includes a region 302, a region 303, and a region 304. The shoulder model region 32B includes a region 301 and a region 305.

  The area (size) of the region 301 is determined so as to correspond to the area (size) of the region 101. The area (size) of the region 302 is determined so as to correspond to the area (size) of the region 102. The area (size) of the region 303 is determined so as to correspond to the area (size) of the region 103. The area (size) of the region 304 is determined so as to correspond to the area (size) of the region 104. The area (size) of the region 305 is determined so as to correspond to the area (size) of the region 105. In the present embodiment, the area of the region 101 and the area of the region 105 are smaller than the area of the region 102, the area of the region 103, and the area of the region 104. The area of the region 101 is substantially equal to the area of the region 105. The area of the region 102, the area of the region 103, and the area of the region 104 are substantially equal. The area of the region 301 and the area of the region 305 are smaller than the area of the region 302, the area of the region 303, and the area of the region 304. The area of the region 301 and the area of the region 305 are substantially equal. The area of the region 302, the area of the region 303, and the area of the region 304 are substantially equal.

As shown in FIG. 10, the size of the region 302 in the Y-axis direction, the size of area 303, and the dimensions of region 304 is _{W c.} Dimensions of the region 302 in the X-axis direction, the size of the region 303, and region 304 is _{L c.} Dimensions of, and the region 305 of the region 301 in the Y-axis direction is _{W s.} Dimensions of the region 301 in the X-axis direction, and the region 305 are _{L s.} The dimension L _c and the dimension L _s correspond to the contact length of the tire 1 (the dimension of the contact surface 10 with respect to the traveling direction).

  In the example illustrated in FIG. 10, the average shear stress, the slip amount, and the friction energy are calculated for each of the region 301, the region 302, the region 303, the region 304, and the region 305.

FIG. 11 is a diagram illustrating an example of the approximate model 30 </ b> C of the ground plane 10 illustrated in FIG. 4. As shown in FIG. 11, the approximate model 30C includes a center model region 31C that models the center region 11, and a shoulder model region 32C that models the shoulder region 12. In the present embodiment, the shoulder model region 32C is divided into a plurality of regions (grounding regions). In the example shown in FIG. 11, the shoulder model region 32C on the −Y side with respect to the center model region 31C is divided into a region 301 _i and a region 301 _o . The shoulder model region 32C on the + Y side with respect to the center model region 31C is divided into a region 305 _i and a region 305 _o . Regarding the Y-axis direction (the width direction of the tire 1), the region 301 _i is disposed closer to the center of the tire 1 than the region 301 _o , and the region 305 _i is disposed closer to the center of the tire 1 than the region 305 _o. . The contact length (average contact length) L _So of the regions 301o and 305o is shorter than the contact length (average contact length) L _Si of the regions 301 _i and 305 _i . The width W _so of the region 301 _o may be longer, shorter, or equal to the width W _si of the region 301 _i . The width of the region 305 _o may be longer, shorter, or equal to the width of the region 305 _i . According to the example shown in FIG. 11, the shoulder model region 32 </ b> C is closer to the shape of the shoulder region 12 of the ground plane 10. Therefore, the friction energy (amount of wear) in the shoulder region 12 can be predicted more accurately.

  FIG. 12 is a diagram showing an example of the approximate model 30D of the ground plane 10 shown in FIG. As shown in FIG. 12, the approximate model 30D is defined by one rectangle (rectangular ground region). That is, in the approximate model 30D, the region 101, the region 102, the region 103, the region 104, the region 105, and the first groove 21 of the ground plane 10 are both modeled as a ground region defined by one rectangle. . According to the example shown in FIG. 12, since the ground contact surface 10 is modeled by one rectangle, the calculation labor is further reduced, and the wear of the tire 1 can be easily obtained.

  FIG. 13 is a diagram illustrating an example of the approximate model 30E of the ground plane 10 illustrated in FIG. As shown in FIG. 13, the approximate model 30E is defined by one octagon (an octagonal grounding region). That is, in the approximate model 30E, both the region 101, the region 102, the region 103, the region 104, the region 105, and the first groove 21 of the ground plane 10 are modeled as a ground region defined by one octagon. Yes. As shown in FIG. 13, the predetermined shape used for the approximate model 30E may be an octagon. The predetermined shape used for the approximate model 30 </ b> E can be appropriately selected according to the shape (outer shape) of the ground plane 10. In the example shown in FIG. 13 as well, since the contact surface 10 is modeled by one octagon (octagon contact region), the calculation labor is further reduced, and the wear of the tire 1 can be easily obtained. Further, since the octagonal ground contact area has a shape closer to the actual outer shape of the ground contact surface 10, the friction energy (amount of wear) can be predicted more accurately.

  FIG. 14 is a diagram illustrating an example of the approximate model 30F of the ground plane 10 illustrated in FIG. As shown in FIG. 14, the approximate model 30F includes a center model region 31F that models the center region 11, and a shoulder model region 32F that models the shoulder region 12. In the present embodiment, the center model region 31F is defined by one rectangle (rectangular ground region). Each of the shoulder model regions 32F is defined by a trapezoid (a trapezoidal grounding region). The shoulder model region 32F includes a side H1 adjacent to the center model region 31F and a side H2 arranged outside the side H1 with respect to the center of the tire 1. The sides H1 and H2 are long in the X-axis direction. With respect to the X-axis direction, the side H2 is shorter than the side H1. According to the example shown in FIG. 14, the shoulder model region (trapezoidal grounding region) 32F of the approximate model 30F is a model closer to the shape of the shoulder region 12 of the grounding surface 10. Therefore, the friction energy (amount of wear) in the shoulder region 12 can be predicted more accurately.

<Third Embodiment>
A third embodiment will be described. FIG. 15 is a diagram illustrating an example of the approximate model 30G according to the present embodiment. The approximate model 30G is an approximate model of the ground plane 10 shown in FIG. The present embodiment is a modification of the above-described embodiment described with reference to FIG.

  In the approximate model 30G, the second groove 22 is considered. Similar to the first groove 21, the second groove 22 is a non-grounding portion that does not contact the road surface. In each of the above-described embodiments, in the approximate model (30 and the like), the second groove 22 is not considered and is treated as a grounding region (grounding part). In the present embodiment, the second groove 22 is considered in the approximate model 30G, and the second groove 22 is treated as a non-grounding region (non-grounding portion) that does not contact the road surface. That is, the approximate model 30G is created with the second groove 22 as a non-grounding region. In the present embodiment, in creating the approximate model 30G, the area of the ground contact region of the approximate model 30G is corrected based on the second groove 22.

  In FIG. 15, the approximate model 30G includes a center model region 31G in which the center region 11 is modeled, and a shoulder model region 32G in which the shoulder region 12 is modeled. The center model region 31G and the shoulder model region 32G are divided with the region (non-grounding region) 211 as a boundary. The center model region 31G is divided into a region 302G, a region 303G, and a region 304G. Region 302G, region 303G, and region 304G are divided with region (non-ground region) 211 as a boundary. That is, in the approximate model 30G, the first groove 21 is taken into consideration, and the first groove 21 is treated as a non-ground portion.

Each of the region 101, the region 102, the region 103, the region 104, and the region 105 of the ground plane 10 includes a second groove (non-ground portion) 22. In the present embodiment, in the approximate model 30G, the area of each of the region 301G, the region 302G, the region 303G, the region 304G, and the region 305G is such that the second groove 22 is not treated as a grounded portion but is treated as a non-grounded portion. It is corrected. For example, in the approximate model 30G, the width W _c ′ is corrected to be smaller than the width W _c of the approximate model 30B described with reference to FIG. Further, in the approximate model 30G, the width W _s ′ is corrected to be smaller than the width W _s of the approximate model 30B described with reference to FIG. The total sum of the width W _s and the width W _c of the approximate model 30B described with reference to FIG. 10 is a dimension obtained by dividing the width of the first groove 21 from the entire width of the ground plane 10. The total sum of the widths of the region 301G, the region 302G, the region 303G, the region 304G, and the region 305G illustrated in FIG. 15 is smaller than the dimension obtained by subtracting the width of the first groove 21 from the entire width of the ground plane 10.

  As described above, according to the present embodiment, not only the first groove 21 but also the second groove 22 is handled as a non-grounding portion, so that the actual area of the ground plane 10 and the ground area in the approximate model 30G can be reduced. The area (the sum of the areas of the region 301G, the region 302G, the region 303G, the region 304G, and the region 305G) is more consistent. Therefore, the wear of the tire 1 can be predicted with higher accuracy.

  FIG. 16 is a diagram illustrating an example of the approximate model 30H of the ground plane 10 illustrated in FIG. As shown in FIG. 16, the approximate model 30H includes a center model region 31H in which the center region 11 is modeled, and a shoulder model region 32H in which the shoulder region 12 is modeled. The approximate model 30H is created using each of the first groove 21 and the second groove 22 as a non-ground region. Center model region 31H and shoulder model region 32H are divided with region (non-ground region) 211 as a boundary. The center model region 31H is divided into a region 302H, a region 303H, and a region 304H. Region 302H, region 303H, and region 304H are divided with region (non-ground region) 211 as a boundary.

In the approximate model 30H, the area of each of the region 301H, the region 302H, the region 303H, the region 304H, and the region 305H is corrected so that the second groove 22 is not treated as a grounding portion but as a non-grounding portion. In the example shown in FIG. 16, the contact length L _2nd of the region 302H and the region 304H is corrected so as to be shorter than the contact length Lc of the approximate model 30B described with reference to FIG. The width _{W 2nd} region 302H and region 304H may be equal to the width _{W c} of the approximate model 30B described with reference to FIG. 10, may be smaller than the width _{W c,} than the width _{W c} May be larger. As described above, the area of the approximate model 30H may be corrected by adjusting not only the size (width) of the grounding region in the Y-axis direction but also the size (grounding length) of the grounding region in the X-axis direction. In the example illustrated in FIG. 16, not only the region 302H and the region 304H but also at least one contact length of the region 301H, the region 303H, and the region 305H may be corrected. Of course, the area of the grounding region may be corrected by correcting both the width and the grounding length of the grounding region.

<Fourth embodiment>
A fourth embodiment will be described. FIG. 17 is a diagram illustrating an example of the approximate model 30I according to the present embodiment. The approximate model 30I is an approximate model of the ground plane 10 shown in FIG. The present embodiment is a modification of the above-described embodiment described with reference to FIG.

  In FIG. 17, an approximate model 30I includes a center model region 31I in which the center region 11 is modeled, and a shoulder model region 32I in which the shoulder region 12 is modeled. The center model region 31I is a combined ground region in which the region 302, the region 303, and the region 304 described with reference to FIG. 10 are combined. The contact length of the region 302 (dimension in the Y-axis direction), the contact length of the region 303, and the contact length of the region 304 are equal. The center model region 31I is formed by combining the region 302, the region 303, and the region 304 having the same ground contact length. The center model region 31I is a grounding region defined by a rectangle.

  The approximate model 30 </ b> B described with reference to FIG. 10 includes five regions 301, 302, 303, 304, and 305 each defined by a rectangle. The approximate model 30I according to the present embodiment includes three regions 32I, a region 32I, and a region 31I. In the present embodiment, the average shear stress, the slip amount, and the frictional energy are obtained for each of the center model region 31I in which the three regions 302, 303, and 304 are combined, and the two shoulder model regions 32I. . By combining the region 302, the region 303, and the region 304 having the same contact length, equivalent friction energy can be obtained more easily.

  FIG. 18 is a diagram illustrating an example of the approximate model 30J according to the present embodiment. An approximate model 30J shown in FIG. 18 is a modification of the approximate model 30I shown in FIG. In FIG. 18, the approximate model 30J includes a center model region 31J and a shoulder model region 32J. The center model region 31J is a combined grounding region formed by combining regions 302, 303, and 304 having the same grounding length. The center model region 31J is a grounding region defined by a rectangle.

  In the example shown in FIG. 18, the shoulder model region 32J is a combined grounding region formed by combining a region 301 and a region 305 having the same grounding length. The shoulder model region 32J is a ground contact region defined by a rectangle. The approximate model 30J according to the present embodiment includes two regions (a center model region 31J and a shoulder model region 32J) defined by a rectangle. In the present embodiment, a center model region 31J in which three regions (region 302, region 303, and region 304) are combined, and a shoulder model region 32J in which two regions (region 301 and region 305) are combined, respectively. , The average shear stress, slip amount, and frictional energy are determined. Also in the example shown in FIG. 18, the equivalent friction energy can be easily obtained.

<Fifth Embodiment>
A fifth embodiment will be described. FIG. 19 is a diagram illustrating an example of a ground contact surface 10K of the tire 1K according to the present embodiment. In the example shown in FIG. 19, the ground contact surface 10K includes a center region 11K and a shoulder region 12K. Two (two) first grooves 21 are provided. The center region 11K and the shoulder region 12K are divided with the first groove 21 as a boundary. A second groove 22 is provided in each of the center region 11K and the shoulder region 12K.

  FIG. 20 is a diagram illustrating an example of the approximate model 30K of the ground plane 10K illustrated in FIG. As shown in FIG. 20, the approximate model 30K of the ground plane 10K may include a ground area defined by a hexagon. In the present embodiment, the approximate model 30K is defined by one hexagon. As described above, the predetermined shape used in the approximate model 30K can be appropriately selected according to the shape (outer shape) of the ground contact surface 10K. In the example shown in FIG. 20 as well, the contact surface 10K is modeled in one contact region defined by a hexagon, so that the calculation effort is reduced and the wear of the tire 1K can be easily obtained.

  FIG. 21 is a diagram illustrating an example of the approximate model 30L of the ground plane 10K illustrated in FIG. As shown in FIG. 21, the approximate model 30L of the ground plane 10K may include a plurality of ground areas each defined by a rectangle. The approximate model 30L includes a center model region 31L in which the center region 11K is modeled, and a shoulder model region 32L in which the shoulder region 12K is modeled. In the approximate model 30L, the first groove 21 is treated as a non-grounding portion that does not contact the road surface. The approximate model 30L is created with the first groove 21 as a non-grounded region. The center model region 31L and the shoulder model region 32L are divided with the region (non-grounding region) 211 as a boundary. The center model region 31L includes three regions 302L, 303L, and 304L each defined by a rectangle. As shown in FIG. 21, an approximate model 30L can be created with five regions 301L, 302L, 303L, 304L, and 305L, each of which is defined by a rectangle, for the ground plane 10K.

  FIG. 22 is a diagram illustrating an example of a ground contact surface 10M of the tire 1M according to the present embodiment. In the example shown in FIG. 22, the ground contact surface 10M includes a center region 11M and a shoulder region 12M. Six (six) first grooves 21 are provided. The center region 11M and the shoulder region 12M are divided with the first groove 21 as a boundary. A second groove 22 is provided in each of the center region 11M and the shoulder region 12M.

  FIG. 23 is a diagram illustrating an example of the approximate model 30M of the ground plane 10M illustrated in FIG. As shown in FIG. 23, the external shape of the approximate model 30M of the ground plane 10M may include a curve. In the example shown in FIG. 23, the approximate model 30M has a shape obtained by cutting a part of an ellipse with a straight line. In the present embodiment, the approximate model 30M is a grounding area defined by one predetermined shape. As described above, the predetermined shape used in the approximate model 30M can be appropriately selected according to the shape (outer shape) of the ground contact surface 10M. Also in the example shown in FIG. 23, since the ground contact surface 10M is modeled in one contact region defined by a predetermined shape, the calculation labor is reduced and the wear of the tire 1M can be easily obtained.

  FIG. 24 is a diagram illustrating an example of the approximate model 30N of the ground contact surface 10M illustrated in FIG. As shown in FIG. 24, the approximate model 30N of the ground plane 10M may include a plurality of ground areas defined by rectangles. The approximate model 30N includes a center model region 31N where the center region 11M is modeled, and a shoulder model region 32N where the shoulder region 12M is modeled. In the approximate model 30N, of the six first grooves 21, the two first grooves 21 that separate the center region 11M and the shoulder region 12M are treated as non-grounding portions that do not contact the road surface. The two first grooves 21 provided in the center region 11M are treated as a grounding portion that comes into contact with the road surface. The 1st groove | channel 21 provided in the shoulder area | region 12M is also handled as a grounding part which contacts a road surface. In the present embodiment, the center model region 31N and the shoulder model region 32N are divided with the region 211 as a boundary. The center model region 31N is formed of one ground region defined by a rectangle. Each of the two shoulder model regions 32N includes two ground contact regions defined by rectangles. The shoulder model region 32N on the −Y side with respect to the center model region 31N includes a region 301i and a region 301o having different areas (sizes). The shoulder model region 32N on the + Y side with respect to the center model region 31N includes a region 305i and a region 305o having different areas (sizes). As in the example shown in FIG. 24, the approximate model 30N can be created with a plurality of ground contact areas defined by rectangles for the ground contact surface 10M.

  In each of the above-described embodiments, when the approximate model 30 of the ground plane 10 is created by a plurality of ground areas defined by a predetermined shape, the first groove 21 (area 211) is divided as a boundary. The plurality of ground regions may be separated by the first groove 21 (region 211) or may not be separated. For example, the area 101 of the ground plane 10 may be approximated by one area defined by a predetermined shape, or an approximate model may be created using a plurality of areas.

<Sixth Embodiment>
A sixth embodiment will be described. FIG. 25 is a flowchart illustrating an example of a procedure of a method for predicting wear of the tire 1 according to the present embodiment.

  In the present embodiment, the average shear stress in the slip region includes an average shear stress in the front-rear direction and an average shear stress in the lateral direction. The slip amount in the slip region includes a slip amount in the front-rear direction and a slip amount in the lateral direction. The procedure for obtaining the frictional energy is to obtain the longitudinal frictional energy based on the average shear stress in the front-rear direction and the amount of slip in the front-rear direction, and based on the average shear stress in the lateral direction and the amount of slip in the lateral direction. Determining lateral frictional energy.

  According to the above-described embodiment, the approximate model 30 of the ground plane 10 is created (step SB1). An approximate function related to the shear stress is set (step SB2). An approximation function related to the slip amount is set (step SB3). A longitudinal force and a lateral force acting on the tire 1 are set (step SB4). The resultant force between the longitudinal force and the lateral force is calculated (step SB5). A slip ratio SR is calculated (step SB6). A slip angle α is calculated (step SB7).

  An average shear stress is calculated (step SB8). That is, as shown in the equation (5), the average shear stress in the center region 11 is calculated based on the resultant force of the longitudinal force and the lateral force, and as shown in the equation (6), the longitudinal force and Based on the resultant force with the lateral force, the average shear stress in the shoulder region 12 is calculated.

  In the present embodiment, the average shear stress in the front-rear direction and the average shear stress in the lateral direction are calculated (step SB9, step SB10).

  The average shear stress in the front-rear direction of the center region 11 is expressed by the following equation (23). The average shear stress in the lateral direction of the center region 11 is expressed by the following equation (24). The average shear stress in the front-rear direction of the shoulder region 12 is expressed by the following equation (25). The average shear stress in the lateral direction of the shoulder region 12 is expressed by the following equation (26).

The average shear stress of the center region 11 can be expressed not only by the equation (5) but also by the following equation (27). _Ac is the ground contact area of the center region 11. A _s is a ground area of the shoulder region 12. The average shear stress in the front-rear direction of the center region 11 is expressed by the following equation (28). The average shear stress in the lateral direction of the center region 11 is expressed by the following equation (29).

The average shear stress of the shoulder region 12 can be expressed not only by the equation (6) but also by the following equation (30). _Ac is the ground contact area of the center region 11. A _s is a ground area of the shoulder region 12. The average shear stress in the front-rear direction of the shoulder region 12 is expressed by the following equation (31). The average shear stress in the lateral direction of the shoulder region 12 is expressed by the following equation (32).

  Next, the amount of slip in the front-rear direction is calculated (step SB11). Further, the slip amount in the horizontal direction is calculated (step SB12).

  The slip amount in the front-rear direction of the center region 11 can be expressed by the following equation (33). The slip amount in the horizontal direction of the center region 11 can be expressed by the following equation (34). The amount of slip in the front-rear direction of the shoulder region 12 can be expressed by the following equation (35). The amount of slip in the lateral direction of the shoulder region 12 can be expressed by the following equation (36).

  Next, the frictional energy in the front-rear direction is calculated (step SB13). Further, the frictional energy in the lateral direction is calculated (step SB14). Further, a total friction energy that is the sum of the friction energy in the front-rear direction and the friction energy in the lateral direction is calculated (step SB15).

  The friction energy in the front-rear direction is obtained based on the average shear stress in the front-rear direction and the amount of slip in the front-rear direction. The frictional energy in the transverse direction is obtained based on the average shear stress in the transverse direction and the amount of slip in the transverse direction.

  That is, the frictional energy in the front-rear direction in the center region 11 is expressed by the following equation (37). The frictional energy in the lateral direction in the center region 11 is expressed by the following equation (38). The total friction energy in the center region 11 is expressed by the following equation (39).

  The frictional energy in the front-rear direction in the shoulder region 12 is expressed by the following equation (40). The frictional energy in the lateral direction in the shoulder region 12 is expressed by the following equation (41). The total friction energy in the shoulder region 12 is expressed by the following equation (42).

  Next, it is determined whether or not calculation of the friction energy has been completed for all of the center model region 31 and the shoulder model region 32 of the approximate model 30 (step SB16). If it is determined in step SB16 that the calculation of friction energy has not been completed for all regions (No), the process returns to step SB8, where it is determined that the calculation of friction energy has been completed for all regions. Until then, the same processing is performed.

  When it is determined in step SB16 that calculation of the friction energy for each of the center model region 31 and the shoulder model region 32 has been completed (in the case of Yes), the analysis unit 52 is based on the friction energy obtained in step SB15. The wear of the tire 1 (tread rubber 6) is predicted (step SB17).

  As described above, according to the present embodiment, the resultant force of the longitudinal force and the lateral force is obtained, and the obtained average shear stress is decomposed into a longitudinal component and a lateral component, and the frictional energy in the longitudinal direction is obtained. And the frictional energy in the lateral direction are obtained, and the frictional energy is obtained by the total. Since the average shear stress, slip amount, and friction energy are handled separately in the front-rear direction component and the lateral direction component, the tire design parameters and the tire characteristic values can be easily matched. Therefore, for example, there is an advantage that it is easy to show a policy for improving the wear performance.

<Seventh embodiment>
A seventh embodiment will be described. FIG. 26 is a flowchart illustrating an example of a procedure of a method for predicting wear of the tire 1 according to the present embodiment.

  In the present embodiment, an approximate function of braking / driving stiffness when a lateral force acts on the tire 1 is set. Further, an approximate function of turning stiffness when a longitudinal force is applied to the tire 1 is set. The slip ratio SR is obtained based on the approximate function of braking / driving stiffness and the lateral force and the longitudinal force acting on the tire 1. The slip angle α is obtained based on the approximate function of the turning stiffness and the longitudinal force and lateral force acting on the tire 1.

  According to the above-described embodiment, the approximate model 30 of the ground plane 10 is created (step SC1). An approximate function related to the shear stress is set (step SC2). An approximation function relating to the slip amount is set (step SC3).

  Next, an approximate function of braking / driving stiffness when a lateral force is applied to the tire 1 is set (step SC4). Further, an approximate function of turning stiffness when a longitudinal force is applied to the tire 1 is set (step SC5).

  The approximate function of braking / driving stiffness is expressed by the following equation (43). The approximate function of the turning stiffness is expressed by the following equation (44).

(43) the approximation function of the braking-driving stiffness in the expression is a function of the lateral force F _y. (44) approximate function of turning stiffness shown in the expression is a function of the longitudinal force F _x. As shown in the following equation (45), the approximate function of braking / driving stiffness may be a function of the lateral force F _y and the longitudinal force F _x acting on the tire 1. As shown in the following equation (46), the approximate function of the turning stiffness may be a function of the longitudinal force F _x and the lateral force F _y acting on the tire 1.

  Next, according to the above-described embodiment, the longitudinal force and the lateral force acting on the tire 1 are set (step SC6). The resultant force between the longitudinal force and the lateral force is calculated (step SC7).

Next, the slip ratio SR is calculated (step SC8). Slip rate SR is determined based on at least one of the lateral force F _y, and longitudinal force F _x acting approximating the function K _x, the tire 1 of the braking-driving stiffness shown in (43) or (45) below . That is, the slip ratio SR is expressed by the following equation (47).

Next, the slip angle α is calculated (step SC9). The slip angle α is obtained based on the approximate function K _y of the turning stiffness shown in the formula (44) or (46) and at least one of the longitudinal force F _x and the lateral force F _y acting on the tire 1. That is, the slip angle α is expressed by the following equation (48).

  Next, the average shear stress is calculated according to the above-described embodiment (step SC10).

  Next, the slip amount is calculated (step SC11). The slip amount is calculated based on the slip ratio SR calculated in step SC8 and the slip angle α calculated in step SC9. The slip amount is calculated by using, for example, Expressions (33) to (36).

  Next, the friction energy is calculated (step SC12). The frictional energy is calculated using, for example, Equation (37) to Equation (42).

  It is determined whether or not the friction energy has been calculated for all regions (step SC13). When it is determined that the friction energy has been calculated for all the regions (in the case of Yes), the analysis unit 52 predicts the wear of the tire 1 based on the friction energy obtained in step SC12 (step SC14).

  As described above, according to this embodiment, by setting an approximate function of braking / driving stiffness when a lateral force is applied and an approximate function of turning stiffness when a longitudinal force is applied, an arbitrary longitudinal force is set. The slip ratio when a lateral force is applied and the slip angle when an arbitrary longitudinal force and lateral force are applied can be easily obtained.

  In the present embodiment, the approximate function of the braking / driving stiffness when the lateral force is applied and the approximate function of the turning stiffness when the longitudinal force is applied may be obtained from actual measurement data or simulation data such as FEM simulation. It may be obtained from statistical prediction data from a database.

<Eighth Embodiment>
An eighth embodiment will be described. FIG. 27 is a flowchart illustrating an example of a procedure of a method for predicting wear of the tire 1 according to the present embodiment.

  In the present embodiment, an approximate function of a slip ratio when a longitudinal force and a lateral force are applied to the tire 1 is set. In addition, an approximate function of a slip angle when a longitudinal force and a lateral force act on the tire 1 is set. The slip ratio SR is obtained based on the approximate function of the slip ratio and the longitudinal force and lateral force acting on the tire 1. The slip angle α is obtained based on the approximate function of the slip angle and the longitudinal force and lateral force acting on the tire 1.

  According to the above-described embodiment, the approximate model 30 of the ground plane 10 is created (step SD1). An approximate function related to the shear stress is set (step SD2). An approximation function relating to the slip amount is set (step SD3).

  Next, an approximate function of the slip ratio when the longitudinal force and the lateral force act on the tire 1 is set (step SD4). Further, an approximate function of the slip angle when the longitudinal force and the lateral force act on the tire 1 is set (step SD5).

  Next, according to the above-described embodiment, the longitudinal force and lateral force acting on the tire 1 are set (step SD6). The resultant force between the longitudinal force and the lateral force is calculated (step SD7).

Next, the slip ratio SR is calculated (step SD8). Further, the slip angle α is calculated (step SD9). The slip ratio SR is obtained based on an approximate function of the slip ratio and at least one of the longitudinal force F _x and the lateral force F _y acting on the tire 1. The slip angle α is obtained based on the approximate function of the slip angle and at least one of the longitudinal force F _x and the lateral force F _y acting on the tire 1.

That is, as shown in equation (49), the slip ratio SR is expressed as a function of the longitudinal force _{F x} and the lateral force _{F y.} As shown in the equation (50), the slip angle α is expressed as a function of the longitudinal force F _x and the lateral force F _y .

  Next, the average shear stress is calculated according to the above-described embodiment (step SD10).

  Next, the slip amount is calculated (step SD11). The slip amount is calculated based on the slip ratio SR calculated in step SD8 and the slip angle α calculated in step SD9. The slip amount is calculated by using, for example, Expressions (33) to (36).

  Next, the friction energy is calculated (step SD12). The frictional energy is calculated using, for example, Equation (37) to Equation (42).

  It is determined whether or not the friction energy has been calculated for all regions (step SD13). When it is determined that the friction energy has been calculated for all the regions (in the case of Yes), the analysis unit 52 predicts the wear of the tire 1 based on the friction energy obtained in step SD12 (step SD14).

  As described above, according to the present embodiment, by setting an approximate function of the slip ratio when the longitudinal force and the lateral force act and an approximate function of the slip angle when the longitudinal force and the lateral force act, The slip ratio when an arbitrary longitudinal force and lateral force are applied and the slip angle when an arbitrary longitudinal force and lateral force are applied can be easily obtained.

  In this embodiment, the approximate function of the slip ratio when the longitudinal force and the lateral force are applied, and the approximate function of the slip angle when the longitudinal force and the lateral force are applied are based on actual measurement data, FEM simulation, or the like. You may obtain | require from simulation data and may obtain | require from the statistical prediction data from a database.

<Ninth Embodiment>
A ninth embodiment will be described. FIG. 28 is a flowchart illustrating an example of a procedure of a method for predicting wear of the tire 1 according to the present embodiment.

  In the present embodiment, a two-dimensional frequency distribution of the longitudinal force and the lateral force acting on the tire 1 is set based on the traveling conditions of the tire 1 including driving, braking, and turning. At each level of the two-dimensional frequency distribution, the average shear stress in the slip region is obtained based on the longitudinal force and lateral force associated with the level and an approximate function related to the shear stress. Further, the slip amount in the slip region is obtained based on the longitudinal force and lateral force associated with the level and an approximate function related to the slip amount. Friction energy is determined based on the determined average shear stress and slip amount. A frequency average friction energy is obtained based on the integrated value of the friction energy and the frequency. Wear of the tire 1 is predicted based on the frequency average friction energy.

  In accordance with the above-described embodiment, the approximate model 30 of the ground plane 10 is created (step SE1). An approximate function related to the shear stress is set (step SE2). An approximation function relating to the slip amount is set (step SE3).

  Next, a two-dimensional frequency distribution of longitudinal force and lateral force is set (step SE4).

The two-dimensional frequency distribution of the longitudinal force and the lateral force acting on the tire 1 is the frequency f when “a certain level of longitudinal force F _xi ” and “a certain level of lateral force F _yj ” are acting on the tire 1. _This refers to the distribution of _ij . For example, when the number of levels of the longitudinal force F _xi is m and the number of levels of the lateral force F _yj is n, the two-dimensional frequency distribution is represented by m × n numbers. That is, the two-dimensional frequency distribution of the longitudinal force and lateral force acting on the tire 1 can be represented by an m × n matrix as shown in Table 1 below.

  The two-dimensional frequency distribution includes a lateral force frequency distribution and a longitudinal force frequency distribution. The lateral force frequency distribution is data indicating the relationship between the lateral force acting on the tire 1 during turning and the frequency at which the lateral force acts. The longitudinal force frequency distribution is data indicating the relationship between the longitudinal force acting on the tire 1 during braking and driving and the frequency at which the longitudinal force acts. In the two-dimensional frequency distribution of the longitudinal force and lateral force acting on the tire 1, there are as many numerical values constituting the longitudinal force frequency distribution as the level number n of the lateral force, and the numerical values constituting the lateral force frequency distribution are There are m levels.

  In general, the lateral force acting on the tire 1 at the time of turning is highly likely to be within a range of −0.5 kN to +0.5 kN. Generally, it is highly possible that the longitudinal force acting on the tire 1 during braking / driving is in the range of −0.5 kN to +0.5 kN. The lateral force frequency distribution and the longitudinal force frequency distribution vary depending on the running conditions of the tire 1 (vehicle).

  In the present embodiment, based on the running conditions of the tire 1 including driving, braking, and turning, the relationship between the longitudinal force and lateral force acting on the tire 1 and the frequency at which the longitudinal force and lateral force are applied 2 is shown. A dimensional frequency distribution is determined. In addition, as described above, the numerical values constituting the longitudinal force frequency distribution exist in the number n of the lateral force level, and the numerical values constituting the lateral force frequency distribution exist in the number m of the longitudinal force frequency. Therefore, in the present embodiment, the longitudinal force frequency distribution indicating the relationship between the longitudinal force acting on the tire 1 and the frequency at which the longitudinal force acts is based on the running conditions of the tire 1 including driving, braking, and turning. Only the number n of lateral force is obtained. Further, based on the running conditions of the tire 1 including driving, braking, and turning, the lateral force frequency distribution indicating the relationship between the lateral force acting on the tire 1 and the frequency at which the lateral force acts is the level m of the longitudinal force. Only required.

  Next, the resultant force of the longitudinal force and the lateral force is calculated at each level of the two-dimensional frequency distribution set in step SE4 (step SE5). Next, the slip rate SR is calculated at each level of the two-dimensional frequency distribution set in step SE4 (step SE6). Further, the slip angle α is calculated at each level of the two-dimensional frequency distribution set in step SE4 (step SE7).

  Next, the average shear stress is calculated (step SE8). In the present embodiment, the analysis unit 52 approximates the resultant force of the longitudinal force and the lateral force associated with each level and the shear stress set in step SE2 at each level of the two-dimensional frequency distribution set in step SE4. Based on the function, the average shear stress in the slip region is obtained.

  In the present embodiment, the relationship between the lateral force, the longitudinal force, and the shear stress is associated. In this embodiment, the shear stress corresponding to each level of the two-dimensional frequency distribution of the lateral force and the longitudinal force is set based on the two-dimensional frequency distribution.

  Next, the slip amount is calculated (step SE9). In the present embodiment, the analysis unit 52 converts the longitudinal force and lateral force associated with each level in the level of the two-dimensional frequency distribution set in step SE4 and the approximate function related to the slip amount set in step SE3. Based on this, the amount of slip in the slip area is obtained.

  In the present embodiment, the relationship between the lateral force, the longitudinal force, and the slip amount is associated. In the present embodiment, a slip amount corresponding to each level of the two-dimensional frequency distribution of the lateral force and the longitudinal force is set based on the two-dimensional frequency distribution.

  Next, the analysis part 52 calculates | requires friction energy based on the average shear stress calculated by step SE8, and the slip amount calculated by step SE9 (step SE10).

  When the approximate model 30 includes a plurality of ground contact areas (for example, the area 301, the area 302, the area 303, the area 304, the area 305, and the like), the above-described processing is performed until the friction energy is calculated for all the ground contact areas. Is repeated (step SE11). Further, the above-described processing is repeated until the friction energy for all levels of the two-dimensional frequency distribution is calculated (step SE12).

  In step SE11, the friction energy for all the contact areas is calculated, and in step SE12, it is determined that the friction energy for all the frequencies has been calculated, and then the analysis unit 52 calculates the integrated value of the friction energy and the frequency. Based on this, the frequency average friction energy is obtained (step SE13).

In the present embodiment, the frequency average friction energy is obtained from the integrated value of the lateral force, the longitudinal force, the friction energy, and the frequency, and the wear of the tire 1 is predicted based on the frequency average friction energy. The frequency average friction energy is the product of the friction energy and the frequency of m × n number when the product of the friction energy and the frequency is obtained for each of m number of longitudinal forces and n number of lateral forces having different values. A value obtained by dividing (dividing) the sum (integrated value) by the sum of frequencies (integrated value). That is, the longitudinal force of each level is F _xi (i = 1 to m), the lateral force of each level is F _yj (j = 1 to n), the frequency of each level is f _ij, and the friction energy of each level is E _{When ij} is set, the frequency average friction energy E _ave is obtained by the following equation (51). That is, the frequency average friction energy E _ave is a value obtained by dividing the sum of products of the friction energy E _ij and the frequency f _{ij by} the sum of the frequencies f _ij .

  That is, in this embodiment, the product of the friction energy and the frequency corresponding to each of a plurality of longitudinal forces (longitudinal force levels) and lateral forces (lateral force levels) having different values is obtained. The analysis part 52 calculates | requires frequency average friction energy based on the longitudinal force or lateral force, and the integrated value of friction energy and frequency (step SE13). When the product of friction energy and frequency is calculated for each of m number of longitudinal force and n number of lateral force with different values, the sum (integrated value) of the product of the friction energy and frequency of m × n number is the frequency. The frequency average friction energy is obtained by dividing (dividing) by the sum (integrated value).

  After the calculation of the frequency average friction energy is completed, the wear of the tire 1 is predicted based on the frequency average friction energy (step SE14).

  As described above, according to the present embodiment, the accuracy of wear prediction of the tire 1 can be further improved by considering the two-dimensional frequency distribution including the lateral force frequency distribution and the longitudinal force frequency distribution.

  That is, in order to obtain the friction energy based on the two-dimensional frequency distribution of the longitudinal force and the lateral force acting on the tire 1, in addition to the tire friction energy characteristics when the pure longitudinal force and the lateral force act, The tire friction energy characteristics can be dealt with in detail also for compound conditions in which force acts simultaneously. Thereby, the wear prediction accuracy of the tire 1 can be further improved.

  In the present embodiment, the two-dimensional frequency distribution of the longitudinal force and the lateral force acting on the tire may be obtained by actual measurement in a predetermined vehicle and running conditions, or may be obtained from a dynamic vehicle motion simulation. .

<Tenth Embodiment>
A tenth embodiment will be described. FIG. 29 is a flowchart illustrating an example of a procedure of a method for predicting wear of the tire 1 according to the present embodiment.

  In accordance with the above-described embodiment, the approximate model 30 of the ground plane 10 is created (step SF1). An approximate function related to the shear stress is set (step SF2). An approximation function relating to the slip amount is set (step SF3).

  Next, a two-dimensional frequency distribution of longitudinal acceleration and lateral acceleration acting on the vehicle is set based on the traveling condition of the vehicle on which the tire 1 is mounted (step SF4).

  The two-dimensional frequency distribution includes a lateral acceleration frequency distribution and a longitudinal acceleration frequency distribution. The lateral acceleration frequency distribution is data indicating the relationship between the lateral acceleration acting on the vehicle (tire 1) during turning and the frequency at which the lateral acceleration acts. The longitudinal acceleration frequency distribution is data indicating the relationship between the longitudinal acceleration acting on the vehicle (tire 1) during braking and driving and the frequency at which the longitudinal acceleration acts.

  In general, the turning acceleration of the vehicle during turning is highly likely to be within a range of −0.1 G or more and +0.1 G or less. In general, the braking / driving acceleration of the vehicle during braking / driving is likely to be within a range of −0.1 G or more and +0.1 G or less. Note that the acceleration frequency distribution (turning acceleration frequency distribution and braking / driving acceleration frequency distribution) varies depending on the running condition of the tire 1 (vehicle).

  In the present embodiment, the longitudinal acceleration frequency distribution indicating the relationship between the longitudinal acceleration acting on the tire 1 and the frequency at which the longitudinal acceleration acts is obtained based on the running conditions of the vehicle including driving, braking, and turning. Good. Further, a lateral acceleration frequency distribution indicating the relationship between the lateral acceleration acting on the tire 1 and the frequency at which the lateral acceleration acts may be obtained based on the running conditions of the vehicle including driving, braking, and turning.

  Next, the analysis unit 52 sets the relationship between the lateral acceleration and the longitudinal acceleration and the longitudinal force and lateral force acting on the tire 1. That is, the lateral force and the longitudinal force acting on the tire 1 are associated with the acceleration frequency distribution (two-dimensional acceleration frequency distribution including the lateral acceleration frequency distribution and the longitudinal acceleration frequency distribution). The lateral force and the longitudinal force acting on the tire 1 can be expressed as a function of the turning acceleration and braking / driving acceleration acting on the vehicle. The analysis unit 52 associates the lateral force and the longitudinal force acting on the tire 1 with each level of the two-dimensional frequency distribution (step SF5).

  Next, the resultant force of the longitudinal force and the lateral force is calculated at each level of the two-dimensional frequency distribution set in step SF4 (step SF6). Next, the slip rate SR is calculated at each level of the two-dimensional frequency distribution set in step SF4 (step SF7). Further, the slip angle α is calculated at each level of the two-dimensional frequency distribution set in step SF4 (step SF8).

  Next, the average shear stress is calculated (step SF9). In the present embodiment, the analysis unit 52 approximates the resultant force of the longitudinal force and the lateral force associated with the level and the shear stress set in step SF2 at each level of the two-dimensional frequency distribution set in step SF4. Based on the above, the average shear stress in the slip region is obtained.

  In the present embodiment, the relationship between the lateral acceleration, the longitudinal acceleration, and the shear stress is associated. In the present embodiment, the shear stress corresponding to each level of the two-dimensional frequency distribution of the lateral acceleration and the longitudinal acceleration is set based on the two-dimensional acceleration frequency distribution.

  Next, the slip amount is calculated (step SF10). In the present embodiment, the analysis unit 52 calculates the longitudinal force and lateral force associated with each level in the level of the two-dimensional frequency distribution set in step SF4 and the approximate function related to the slip amount set in step SF3. Based on this, the amount of slip in the slip area is obtained.

  In the present embodiment, the relationship between the lateral acceleration, the longitudinal acceleration, and the slip amount is associated. In the present embodiment, a slip amount corresponding to each level of the lateral acceleration and the longitudinal acceleration of the two-dimensional frequency distribution is set based on the two-dimensional acceleration frequency distribution.

  Next, the analysis part 52 calculates | requires friction energy based on the average shear stress calculated by step SF9, and the slip amount calculated by step SF10 (step SF11).

  When the approximate model 30 includes a plurality of ground contact areas (for example, the area 301, the area 302, the area 303, the area 304, the area 305, and the like), the above-described processing is performed until the friction energy is calculated for all the ground contact areas. Is repeated (step SF12). Further, the above-described processing is repeated until the frictional energy for all levels of the two-dimensional frequency distribution is calculated (step SF13).

  In step SF12, the friction energy for all the contact areas is calculated, and in step SF13, it is determined that the friction energy for all frequencies is calculated, and then the analysis unit 52 calculates the integrated value of the friction energy and the frequency. Based on this, the frequency average friction energy is obtained (step SF14).

  In the present embodiment, the frequency average friction energy is obtained from the integrated value of the lateral acceleration, the longitudinal acceleration, the friction energy, and the frequency, and the wear of the tire 1 is predicted based on the frequency average friction energy. The frequency average friction energy is the product of the friction energy and the frequency of m × n number when the product of the friction energy and the frequency is obtained for each of m number of longitudinal accelerations and n number of lateral accelerations having different values. A value obtained by dividing (dividing) the sum (integrated value) by the sum of frequencies (integrated value).

  That is, in the present embodiment, a product of friction energy and frequency corresponding to each of a plurality of longitudinal accelerations (longitudinal acceleration levels) and lateral accelerations (lateral acceleration levels) having different values is obtained. The analysis unit 52 obtains the frequency average friction energy based on the longitudinal acceleration or the lateral acceleration and the integrated value of the friction energy and the frequency (step SF14). When the product of the frictional energy and the frequency is obtained for each of m number of longitudinal accelerations and n number of lateral accelerations having different values, the sum (integrated value) of the products of the frictional energy and the frequency of m × n number is the frequency. The frequency average friction energy is obtained by dividing (dividing) by the sum (integrated value).

  After the calculation of the frequency average friction energy is completed, the wear of the tire 1 is predicted based on the frequency average friction energy (step SF15).

  As described above, according to the present embodiment, the accuracy of wear prediction of the tire 1 can be further improved by considering the two-dimensional frequency distribution including the lateral acceleration frequency distribution and the longitudinal acceleration frequency distribution.

  That is, since the longitudinal force and lateral force acting on the tire 1 are associated with the two-dimensional frequency distribution of the longitudinal acceleration and lateral acceleration acting on the vehicle and the frictional energy is obtained based on the longitudinal force and lateral force, In addition to the tire friction energy characteristics when force and lateral force are applied, the tire friction energy characteristics can also be handled in detail for a composite condition in which longitudinal force and lateral force are applied simultaneously. Thereby, the wear prediction accuracy of the tire 1 can be further improved.

  Note that the two-dimensional frequency distribution of the longitudinal acceleration and the lateral acceleration acting on the vehicle may be obtained by actual measurement in a predetermined vehicle and running conditions, or may be obtained from a dynamic vehicle motion simulation.

  It should be noted that the relationship between the acceleration acting on the vehicle and the longitudinal force and lateral force acting on the tire 1 may be obtained by actual measurement under a predetermined condition or may be obtained from an approximate expression obtained by regression from the actual measurement value. Alternatively, it may be obtained from a dynamic vehicle motion simulation, or may be estimated from an estimation formula obtained analytically from vehicle specifications.

<Eleventh embodiment>
An eleventh embodiment will be described. The eleventh embodiment is a modification of the ninth embodiment or the tenth embodiment described above.

  In the ninth embodiment or the tenth embodiment described above, an initial load acting on the tire 1 is set. The initial load includes a load that acts on the tire 1 when the tire 1 is not running.

  A load acting on the tire 1 when the vehicle is stationary is set. The load acting on the tire 1 when the vehicle is stationary may be acquired from actual measurement data, or may be set based on vehicle specification data.

  Next, a load acting on the tire 1 when the vehicle is traveling is set. The load acting on the tire 1 when the vehicle is traveling may be acquired from actually measured data under each condition of braking / driving and turning, or may be obtained from an approximate expression regressed from the actually measured value. Alternatively, it may be obtained from a dynamic vehicle motion simulation or may be estimated from an estimation formula obtained analytically from vehicle specifications.

  Next, a first load correction function and a second load correction function related to friction energy are set.

  The first load correction function is a function for obtaining the friction energy (first load correction friction energy) corrected in the load when the vehicle is stationary in consideration of the load dependency of the friction energy. The second load correction function is a function for obtaining the friction energy (second load correction friction energy) corrected in the load when the vehicle travels in consideration of the load dependency of the friction energy. The friction energy is a function of the load acting on the tire 1 and is a numerical value that changes according to the load acting on the tire 1. The load acting on the tire 1 changes according to the traveling condition of the vehicle on which the tire 1 is mounted.

  By properly considering the load when the vehicle is stationary and the load when the vehicle is running, the tire wear performance can be predicted with high accuracy while acquiring friction energy under a small initial load condition. The load when the vehicle travels varies depending on braking and turning. By properly considering the influence of the load, the tire wear performance can be accurately predicted.

  The first load correction function is a function relating to a condition in which the lateral force and the longitudinal force acting on the tire 1 change in proportion to the change in load. The second load correction function is a function relating to a condition in which the longitudinal force and the lateral force are constant regardless of changes in the load.

  The condition (first condition) in which the lateral force and the longitudinal force acting on the tire 1 change in proportion to the change in the load acting on the tire 1 is, for example, the weight (vehicle weight) of the vehicle on which the tire 1 is mounted. It includes a condition that the lateral force and the longitudinal force change due to the change. The condition that the lateral force and the longitudinal force acting on the tire 1 are constant regardless of the change in the load (second condition) is, for example, a condition in which the load acting on the tire 1 changes due to turning and acceleration / deceleration of the vehicle. Including. That is, when the vehicle weight changes, the lateral force and the longitudinal force acting on the tire 1 change when the vehicle makes a predetermined turn and acceleration / deceleration. When the vehicle makes a predetermined turn and acceleration / deceleration without changing the vehicle weight, the load acting on the tire 1 changes, but there is a high possibility that the lateral force and the longitudinal force do not change. The first condition and the second condition differ in the tendency of the relationship between the load acting on the tire 1 and the friction energy.

  According to the knowledge of the present inventor, it has been found that, under the first condition, when the load increases, the friction energy increases, and when the load decreases, the friction energy tends to decrease. On the other hand, it has been found that, under the second condition, the friction energy decreases as the load increases, and the friction energy increases as the load decreases. Therefore, it is preferable that the load correction function is set in accordance with an assumed condition (either the first condition or the second condition).

  The load correction function includes at least one of a load correction function in a turning condition and a load correction function in a braking / driving condition (braking condition and driving condition).

  According to the knowledge of the present inventor, it has been found that the load dependence of the frictional energy differs between the turning condition and the braking / driving condition. This is considered to be because the load dependency of the turning stiffness is different from the load dependency of the braking / driving stiffness. Therefore, the load dependency of the friction energy is different between the turning condition and the braking / driving condition. Therefore, the wear performance can be predicted with higher accuracy by separately setting the load correction function in the turning condition and the load correction function in the braking / driving condition and performing the load correction respectively. As a load correction function, a correction formula that reproduces the average tendency of the turning condition and the braking / driving condition may be adopted.

  In the present embodiment, a function (load correction function) for correcting the friction energy is set, and the load correction friction energy is determined based on the load correction function. The load correction function may be a linear function, a function of 2nd to 6th order, a power function, an exponential function, or a function combining these functions. It is not restricted to these examples, Arbitrary functions can be used. An example of a linear function for the first load correction function is shown in equation (52A), an example of a quaternary function is shown in equation (52B), and an example of a power function is shown in equation (52C). An example of a linear function for the second load correction function is shown in equation (53A), an example of a quaternary function is shown in equation (53B), and an example of a power function is shown in equation (53C).

  In the equations (52A) to (52C) and (53A) to (53C), the constant a, the constant b, the constant c, the constant d, and the constant n are obtained in advance by, for example, an experiment (preliminary experiment). Alternatively, it may be obtained in advance by simulation. When obtaining by experiment, the load correction function is set by running (rolling) the tire 1 in a state where the load is actually applied to the tire 1 and measuring the friction energy at that time with a predetermined measuring device. May be. In the case of obtaining by simulation, the load correction function may be set by obtaining friction energy based on predetermined load conditions and running conditions. By obtaining a plurality of relationships between the load and the friction energy, the constant a, constant b, constant c, constant d, and constant n can be obtained.

  When the vehicle weight changes due to differences in vehicles, grades, loading amounts, etc., it is preferable to use a load correction function relating to a condition in which the longitudinal force and lateral force change in proportion to the load.

  When the tire load changes due to turning and acceleration / deceleration during traveling of the vehicle, it is preferable to use a load correction function relating to a condition in which the longitudinal force and the lateral force are constant.

  When a power function is used for the first load correction function, the power coefficient n is preferably 0.5 or more and 2.0 or less, and more preferably 0.7 or more and 1.4 or less.

  When a power function is used for the second load correction function, the power coefficient n is preferably −1.5 or more and −0.2 or less, and more preferably −1.3 or more and −0.6 or less.

  The tire wear performance can be accurately predicted by appropriately considering the influence of the load acting on the tire 1.

  In the case where the initial load and the load acting on the tire 1 when the vehicle is stationary are substantially the same, the procedure for obtaining the first load correction friction energy may be omitted.

  According to the ninth embodiment or the tenth embodiment described above, a two-dimensional frequency distribution of longitudinal force and lateral force acting on the tire 1 or a two-dimensional frequency distribution of longitudinal acceleration and lateral acceleration acting on the vehicle is set.

  In the present embodiment, a load acting on the tire 1 is associated with each level of the two-dimensional frequency distribution.

  Next, tire characteristic parameters of the first approximate function and the second approximate function are set based on the initial load at each level of the two-dimensional frequency distribution. The tire characteristic parameter includes at least one of a contact length, a contact width, a contact area, a turning stiffness, and a braking / driving stiffness.

  Based on the tire characteristic parameter, an approximate function related to shear stress and an approximate function related to slip amount are set.

  Next, according to the ninth embodiment or the tenth embodiment described above, the average shear stress in the slip region is calculated based on the longitudinal force and lateral force associated with each level of the two-dimensional frequency distribution and the approximate function related to the shear stress. It is obtained (refer to step SE8, step SF9).

  Further, according to the ninth embodiment or the tenth embodiment described above, the slip amount in the slip region is obtained based on the longitudinal force and the lateral force associated with each level of the two-dimensional frequency distribution and the approximate function related to the slip amount. (Refer to step SE9 and step SF10).

  Next, the friction energy is obtained based on the average shear stress and the slip amount (see step SE10 and step SF11).

  After the frictional energy is obtained, the analysis unit 52 corrects the frictional energy based on the load acting on the tire 1 and the first load correction function when the vehicle is stationary, and the first load on the contact surface 10 is obtained. Find the corrected friction energy. The friction energy is a function of the load acting on the tire 1 and is a numerical value that changes according to the load acting on the tire 1. The load acting on the tire 1 changes according to the weight (vehicle weight) of the vehicle on which the tire 1 is mounted. The analysis unit 52 is assumed to have a load acting on the tire 1 when stationary, and corrects the friction energy based on the assumed load and the first load correction function to obtain the first load correction friction energy. .

  In the present embodiment, the first load correction friction energy is calculated in association with the longitudinal force and lateral force of the two-dimensional frequency distribution.

  Next, the analysis unit 52 corrects the first load correction frictional energy based on the load acting on the tire 1 and the second load correction function when the vehicle travels, and the second load on the ground contact surface 10 is corrected. Find the corrected friction energy. The friction energy is a function of the load acting on the tire 1 and is a numerical value that changes according to the load acting on the tire 1. The load acting on the tire 1 changes according to the traveling condition of the vehicle on which the tire 1 is mounted. The analysis unit 52 assumes a load acting on the tire 1 during traveling, corrects the first load correction friction energy based on the assumed load and the second load correction function, and outputs the second load. Find the corrected friction energy.

  In the present embodiment, the second load correction friction energy is calculated in association with the longitudinal force and lateral force of the two-dimensional frequency distribution.

  When the friction energy at the initial load is E, the first load correction friction energy E ′ and the second load correction friction energy E ″ are expressed by the following equations (54) and (55).

  After the second load correction friction energy is obtained, the analysis unit 52 obtains the frequency average friction energy based on the integrated value of the second load correction friction energy and the frequency (see step SE13 and step SF14).

  The analysis unit 52 predicts the wear of the tire 1 based on the frequency average friction energy obtained using the second load correction friction energy (see step SE14 and step SF15).

  As described above, according to the present embodiment, the tire wear performance can be improved more accurately by taking into account the effects based on the load when the vehicle is stationary and the load that changes due to turning and braking / driving when the vehicle is running. Can be predicted.

<Twelfth embodiment>
A twelfth embodiment will be described. The twelfth embodiment is a modification of the ninth embodiment or the tenth embodiment described above.

  In the present embodiment, the tire characteristic parameter of the approximate function related to the shear stress and the approximate function related to the slip amount is set as a function using the load as a variable. The tire characteristic parameter includes at least one of a contact length, a contact width, a contact area, a turning stiffness, and a braking / driving stiffness. Examples of the first approximate function and the second approximate function in which the load is a variable are shown in Expressions (56A) to (56E).

  Equation (56A) shows an example in which the first approximation function and the second approximation function are linear functions. Equation (56B) shows an example in which the first approximation function and the second approximation function are quartic functions. Equation (56C) shows an example in which the first approximation function and the second approximation function are power functions. Equation (56D) shows an example in which the first approximation function and the second approximation function are exponential functions. Expression (56E) shows an example of a function in which the first approximation function and the second approximation function are a combination of a trigonometric function and a power function.

  According to the ninth embodiment or the tenth embodiment described above, a two-dimensional frequency distribution of longitudinal force and lateral force acting on the tire 1 or a two-dimensional frequency distribution of longitudinal acceleration and lateral acceleration acting on the vehicle is set.

  In the present embodiment, a load acting on the tire 1 is associated with each level of the two-dimensional frequency distribution.

  The analysis unit 52 determines the tire characteristic parameter of the first approximate function and the second approximate function based on the load associated with the level at each level of the two-dimensional frequency distribution, and based on the tire characteristic parameter, A first approximation function and a second approximation function are set.

  After the first approximate function and the second approximate function are set, the analysis unit 52 is based on the longitudinal force, the lateral force, and the first approximate function according to the ninth embodiment or the tenth embodiment described above. Then, the average shear stress in the slip region is obtained (see step SE8 and step SF9).

  In addition, the analysis unit 52 obtains the slip amount of the slip region based on the longitudinal force, the lateral force, and the second approximate function according to the ninth embodiment or the tenth embodiment (see step SE9 and step SF10). ).

  Next, the analysis part 52 calculates | requires friction energy based on an average shear stress and slippage (refer step SE10, step SF11).

  Next, the analysis part 52 calculates | requires frequency average friction energy based on the integrated value of friction energy and frequency (refer step SE13, step SF14).

  Next, the analysis unit 52 predicts wear of the tire 1 based on the frequency average frictional energy (see step SE14 and step SF15).

  As described above, according to the present embodiment, the load dependency of the tire characteristic parameter is considered, and the load dependency of the frictional energy is directly considered based on the tire characteristic parameter value in the load during traveling. Wear prediction accuracy is further improved.

<13th Embodiment>
A thirteenth embodiment will be described. In the present embodiment, the wear of the tread rubber 6 per unit travel distance is based on the radius of the tire 1 (dynamic load radius), the wear amount per unit friction energy of the tread rubber 6, and the obtained friction energy. A procedure for obtaining the amount and a procedure for predicting the wear of the tire 1 (tread rubber 6) based on the obtained wear amount of the tread rubber 6 are executed. The radius of the tire 1 is a rolling radius obtained by dividing the distance rolled when the tire 1 makes one rotation by 2π.

  FIG. 30 is a schematic diagram showing a state where the tire 1P having a large radius and the tire 1Q having a small radius are rolling. The tire 1 (tread rubber 6) is worn by contact with the road surface. When the tire 1P and the tire 1Q travel the same distance, the tire 1Q having a small radius rolls more than the tire 1P having a large radius, and has more opportunities to contact the road surface. Therefore, the tire 1Q having a smaller radius is more easily worn than the tire 1P having a larger radius. Therefore, the wear amount of the tread rubber 6 per unit travel distance can be obtained based on the radius of the tire 1, the wear amount per unit friction energy of the tread rubber 6, and the obtained friction energy. The amount of wear per unit friction energy of the tread rubber 6 depends on the material characteristics (wear resistance) of the tread rubber 6. The wear of the tire 1 (tread rubber 6) is predicted based on the obtained wear amount of the tread rubber 6 per unit travel distance.

  According to the present embodiment, in addition to the wear resistance physical properties of the tread rubber 6, the influence of the radius of the tire 1 (dynamic load radius) is taken into consideration, thereby taking into account the difference in the rotation speed of the tire 1 per unit travel distance. Thus, the wear of the tire 1 can be predicted with higher accuracy.

  In the above-described embodiments, the wear life of the tire 1 may be predicted based on the wear amount of the tread rubber 6 per unit travel distance and the effective groove depth.

<Fourteenth embodiment>
A fourteenth embodiment will be described. In the embodiment described above, the procedure for predicting the wear of the tire 1 for each of the right wheel and the left wheel of the vehicle on which the tire 1 is mounted, and the average wear of the wear of the right wheel tire 1 and the wear of the left wheel tire 1 are as follows. And a predicting procedure.

  According to this embodiment, in addition to the difference between the right wheel and the left wheel due to driving conditions and the difference between the right wheel and the left wheel due to the cant of the road surface and the vehicle alignment, the difference in the load between the right wheel and the left wheel due to these differences is considered. In addition, by averaging, it is possible to predict the average wear of the tire 1 in consideration of the difference between the right wheel and the left wheel.

<Fifteenth embodiment>
A fifteenth embodiment is described. In each of the above-described embodiments, the procedure for predicting the wear of the tire 1 for each of the front and rear wheels of the vehicle to which the tire 1 is mounted, and the average wear of the wear of the front tire 1 and the wear of the rear tire 1 And a procedure for predicting one or both of the wear ratio between the wear of the front tire 1 and the wear of the rear tire 1 may be included.

  According to the present embodiment, by considering the difference between the front and rear wheels due to the vehicle and driving conditions, and the difference in load between the front and rear wheels due to these differences, the tire wear during rotation and the front and rear wheels The wear ratio can be accurately predicted.

  In each of the above embodiments, the wear prediction of the tire 1 is performed by a computer. All of the wear prediction methods for the tire 1 according to the present embodiment may be performed by a computer, a part may be performed by a computer, a part may be performed manually, or all may be performed manually. Also good.

<Example>
Next, examples according to the present invention will be described. The inventor performed a running test on an actual tire, and predicted the wear of the tire 1 according to the above-described embodiment, and compared the wear state of the actual tire 1 with the wear prediction.

  In the running test, an FF vehicle having a displacement of 1.3 L was used as a test vehicle, and a test tire was attached to the test vehicle, and each of the three types of test courses with different running modes was run for 8000 km.

  The test course 1 is a braking / driving course. The test course 2 is a turning-oriented course. Test course 3 is a mixed course of braking and driving.

  In the test, the average wear life of the left and right wheels was determined from the wear amount of the main groove of the drive wheel (front wheel) and the effective groove depth, and the indexes were compared with the reference tire as 100 respectively. A larger index indicates a longer wear life.

  FIG. 31 and FIG. 32 show the comparison results. FIG. 31 shows a comparative example (conventional example). In FIG. 31, the horizontal axis represents the amount of wear obtained from a running test using actual tires. The vertical axis is the predicted value of the amount of wear in the conventional example. In the conventional example, for each level of the longitudinal acceleration frequency distribution and the lateral acceleration frequency distribution when the vehicle is running, the frictional energy is calculated at each level of the frequency distribution by associating the longitudinal force and the lateral force acting on the tire. The amount of wear was predicted by calculating the average friction energy from the frequency average friction energy in the front-rear direction and the frequency average friction energy in the lateral direction.

  FIG. 32 shows an embodiment according to the present invention. In FIG. 32, the horizontal axis indicates the amount of wear obtained from a running test using actual tires. The vertical axis is the predicted value of the wear amount in the embodiment of the present invention. For each level of the two-dimensional frequency distribution of the longitudinal acceleration and lateral acceleration when the vehicle travels, the frictional energy is calculated at each level of the two-dimensional frequency distribution by associating the longitudinal force and the lateral force acting on the tire. The amount of wear was predicted from the average friction energy.

  31 and 32, “◯” indicates the result for the test course 1, “は” indicates the result for the test course 2, and “Δ” indicates the result for the test course 3.

  The smaller the difference between the wear life (wear amount) obtained from the running test and the wear life (wear amount) predicted based on the wear prediction method, the more the actual wear test result matches the wear prediction result. It will be. In order to make the figure easy to understand, a line indicating y = x is also shown in the graphs of FIGS. 31 and 32. The closer each of “◯”, “◇”, and “Δ” is located near the line indicating y = x, the more the actual wear test result matches the wear prediction result.

  As shown in FIG. 31, in the conventional example, the wear life in the test course 3 is longer than that in the actual vehicle, whereas in the embodiment, the correlation with the actual vehicle is improved in the test course 3 as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Tire 2 Carcass 3 Belt layer 3A 1st belt ply 3B 2nd belt ply 4 Belt cover 5 Bead core 6 Tread rubber 7 Side wall rubber 10 Ground surface 11 Center area 12 Shoulder area 21 1st groove 22 2nd groove 30 Approximate model 31 Center model area 32 Shoulder model area 50 Processing device 50p Processing section 51 Model creation section 52 Analysis section 71 Side wall section 101 area 102 area 103 area 104 area 105 area 211 area (non-grounding area)
301 area (grounding area)
302 area (ground area)
303 area (grounding area)
304 area (ground area)
305 area (grounding area)

Claims (15)

A procedure for creating an approximate model including a ground contact area defined by a predetermined shape with respect to a road contact surface of a tire with respect to a road surface;
A procedure for setting a first approximation function relating to the shear stress in the slip region of the ground plane;
A procedure for setting a second approximate function relating to the slip amount of the slip area of the ground plane;
A procedure for obtaining a resultant force of a longitudinal force and a lateral force acting on the tire;
A procedure for obtaining a slip ratio and a slip angle when the longitudinal force and the lateral force act on the tire;
Based on the first approximate function and the resultant force, a procedure for obtaining an average shear stress in the slip region;
Based on the second approximate function, the slip ratio, and the slip angle, a procedure for obtaining a slip amount in the slip region;
Based on the average shear stress and the amount of slip, a procedure for obtaining frictional energy at the ground contact surface;
A procedure for predicting wear of the tire based on the obtained frictional energy;
Tire wear prediction method including   The tire wear prediction method according to claim 1, wherein the predetermined shape includes a rectangle. The procedure for determining the average shear stress in the slip region is that the average shear stress obtained from the resultant force of the longitudinal force and the lateral force is decomposed into a longitudinal component and a lateral component, and the average shear stress in the longitudinal direction is obtained. If is intended that the lateral average shear stress,
The slip amount of the slip region includes a slip amount in the front-rear direction and a slip amount in the lateral direction,
The procedure for obtaining the friction energy is as follows:
Based on the average shear stress in the front-rear direction and the amount of slip in the front-rear direction, determining the friction energy in the front-rear direction;
Based on the transverse average shear stress and the amount of slip in the transverse direction, to determine the frictional energy in the transverse direction;
A method for predicting tire wear according to claim 1 or claim 2 comprising: A procedure for setting an approximate function of braking / driving stiffness when a lateral force acts on the tire;
A procedure for setting an approximate function of turning stiffness when a longitudinal force acts on the tire;
Including
The slip ratio is determined based on an approximate function of the braking / driving stiffness and a lateral force and a longitudinal force acting on the tire,
The tire wear prediction method according to any one of claims 1 to 3, wherein the slip angle is obtained based on an approximation function of the turning stiffness and a longitudinal force and a lateral force acting on the tire. A procedure for setting an approximate function of the slip ratio when a longitudinal force and a lateral force act on the tire;
A procedure for setting an approximate function of the slip angle when a longitudinal force and a lateral force act on the tire;
Including
The slip ratio is determined based on an approximate function of the slip ratio, and longitudinal force and lateral force acting on the tire,
The tire slip prediction method according to any one of claims 1 to 3, wherein the slip angle is obtained based on an approximate function of the slip angle and a longitudinal force and a lateral force acting on the tire. A procedure for setting a two-dimensional frequency distribution of longitudinal force and lateral force acting on the tire based on the running conditions of the tire including driving, braking, and turning;
In each level of the two-dimensional frequency distribution, a procedure for obtaining an average shear stress in the slip region based on the longitudinal force and lateral force associated with the level and the first approximate function;
A procedure for obtaining a slip amount in a slip region based on the longitudinal force and lateral force associated with the level and the second approximate function;
A procedure for obtaining the friction energy based on the average shear stress and the slip amount;
Based on the integrated value of the friction energy and the frequency, a procedure for obtaining a frequency average friction energy;
A procedure for predicting wear of the tire based on the frequency average frictional energy;
The tire wear prediction method according to any one of claims 1 to 5, further comprising: A procedure for setting a two-dimensional frequency distribution of longitudinal acceleration and lateral acceleration acting on the vehicle based on a running condition of the vehicle on which the tire is mounted;
A procedure for associating lateral force and longitudinal force acting on the tire with each level of the two-dimensional frequency distribution;
In each level of the two-dimensional frequency distribution, a procedure for obtaining an average shear stress in the slip region based on the longitudinal force and lateral force associated with the level and the first approximate function;
A procedure for obtaining a slip amount in a slip region based on the longitudinal force and lateral force associated with the level and the second approximate function;
A procedure for obtaining the friction energy based on the average shear stress and the slip amount;
Based on the integrated value of the friction energy and the frequency, a procedure for obtaining a frequency average friction energy;
A procedure for predicting tire wear based on the frequency average frictional energy;
The tire wear prediction method according to any one of claims 1 to 5, further comprising: A procedure for setting an initial load acting on the tire;
A procedure for setting a first load correction function and a second load correction function for the friction energy;
A procedure for associating a load acting on the tire with each level of the two-dimensional frequency distribution of the longitudinal force and the lateral force acting on the tire or the two-dimensional frequency distribution of the longitudinal acceleration and the lateral acceleration acting on the vehicle;
A procedure for setting tire characteristic parameters of the first approximate function and the second approximate function based on the initial load at each level of the two-dimensional frequency distribution;
A procedure for setting the first approximate function and the second approximate function based on the tire characteristic parameter;
Based on the longitudinal force and lateral force associated with the level and the first approximate function, a procedure for obtaining an average shear stress in the slip region;
A procedure for obtaining a slip amount in a slip region based on the longitudinal force and lateral force associated with the level and the second approximate function;
Based on the average shear stress and the amount of slip, a procedure for obtaining friction energy,
A procedure for obtaining a first load correction friction energy associated with a longitudinal force and a lateral force based on the load acting on the tire when the vehicle is stationary and the first load correction function;
A procedure of correcting the first load correction friction energy based on the load acting on the tire during the traveling of the vehicle and the second load correction function to obtain a second load correction friction energy;
A procedure for obtaining a frequency average friction energy based on an integrated value of the second load correction friction energy and the frequency;
A procedure for predicting tire wear based on the frequency average frictional energy;
The tire wear prediction method according to claim 6 or 7 including: The first load correction function is a function relating to a condition in which the longitudinal force and the lateral force acting on the tire change in proportion to the change in the load,
The tire wear prediction method according to claim 8, wherein the second load correction function is a function related to a condition in which the longitudinal force and the lateral force are constant regardless of a change in the load. A procedure for setting tire characteristic parameters of the first approximate function and the second approximate function as functions having a load as a variable;
A procedure for associating a load acting on the tire with each level of the two-dimensional frequency distribution of the longitudinal force and the lateral force acting on the tire or the two-dimensional frequency distribution of the longitudinal acceleration and the lateral acceleration acting on the vehicle;
At each level of the two-dimensional frequency distribution, tire characteristic parameters of the first approximate function and the second approximate function are determined based on a load associated with the level, and based on the tire characteristic parameter, A procedure for setting the first approximate function and the second approximate function;
A procedure for determining an average shear stress in a slip region based on longitudinal force and lateral force and the first approximate function;
A procedure for obtaining a slip amount in a slip region based on a longitudinal force and a lateral force and the second approximate function;
A procedure for obtaining the friction energy based on the average shear stress and the slip amount;
Based on the integrated value of the friction energy and the frequency, a procedure for obtaining a frequency average friction energy;
A procedure for predicting wear of the tire based on the frequency average frictional energy;
The tire wear prediction method according to claim 6 or 7 including: Based on the amount of wear per unit friction energy of the tread rubber of the tire and the obtained friction energy, a procedure for obtaining the amount of wear of the tread rubber;
A procedure for predicting the wear of the tire based on the wear amount of the tread rubber,
The tire wear prediction method according to any one of claims 1 to 10, comprising: A procedure for obtaining the wear amount of the tread rubber per unit travel distance based on the radius of the tire, the wear amount per unit friction energy of the tread rubber of the tire, and the obtained friction energy;
A procedure for predicting the wear of the tire based on the wear amount of the tread rubber,
The tire wear prediction method according to claim 1, comprising: A procedure for predicting wear of the tire for each of a right wheel and a left wheel of a vehicle on which the tire is mounted;
A procedure for predicting the average wear of the right wheel wear and the left wheel wear;
The tire wear prediction method according to claim 1, comprising: A procedure for predicting wear of the tire for each of a front wheel and a rear wheel of a vehicle on which the tire is mounted;
A procedure for predicting one or both of an average wear between the front wheel wear and the rear wheel wear, and a wear ratio between the front wheel wear and the rear wheel wear;
The tire wear prediction method according to any one of claims 1 to 13, comprising:   15. A computer program for tire wear prediction, which causes a computer to execute the tire wear prediction method according to any one of claims 1 to 14.

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