Tire wear performance evaluation method and device

Abstract

To provide a method and a device which can maintain wear performance evaluation accuracy while shortening a time required for evaluation of tire wear performance.SOLUTION: Provided are a method and a device for evaluating wear performance of a tread part of a tire. This method includes: a step S1 at which a vehicle to which a tire is mounted is travelled under a plurality of travel conditions including free rolling motion, braking, driving, and turning, to acquire each occurrence frequency of the plurality of travel conditions; a step S2 at which wear energy of the tread part is calculated for each of the plurality of travel conditions; a step S3 at which wear energy is weighted by the occurrence frequency for each of the plurality of travel conditions to determine total wear energy taking all of the plurality of travel conditions into consideration; a step S4 at which a partial travel condition selected from the plurality of travel conditions is decided; and a step S5 at which occurrence frequency of the partial travel condition is decided by multiple regression analysis based on the wear energy corresponding to the partial travel condition and the total wear energy.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method and device for evaluating tire wear performance. [Background technology]

[0002] The following Patent Document 1 describes a method for evaluating tire wear performance. In this method, first, a plurality of use conditions taking into consideration vehicle acceleration and the like and a use condition frequency distribution showing the relationship between the frequencies are acquired. Then, the amount of tire wear is predicted based on the use condition frequency distribution and the wear energy of the tire to be evaluated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-200137 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above method, in order to predict the amount of tire wear, the wear energy is weighted by frequency for each of a number of usage conditions, which causes a problem that it takes a long time to evaluate the wear performance of tires.

[0005] The present invention has been devised in consideration of the above-described circumstances, and has as its main object to provide a method and apparatus that can maintain the evaluation accuracy of wear performance while shortening the time required to evaluate the wear performance of a tire. [Means for solving the problem]

[0006] The present invention is a method for evaluating the wear performance of a tire tread portion, comprising the steps of: running a vehicle equipped with a tire under a plurality of driving conditions including free rolling, braking, driving, and cornering, and obtaining the occurrence frequency of each of the plurality of driving conditions; calculating the wear energy of the tread portion for each of the plurality of driving conditions; weighting the wear energy for each of the plurality of driving conditions by the occurrence frequency to obtain a total wear energy taking into account all of the plurality of driving conditions; determining a portion of driving conditions to be selected from the plurality of driving conditions; and determining the occurrence frequency of the portion of driving conditions by multiple regression analysis based on the wear energy corresponding to the portion of driving conditions and the total wear energy.

[0007] In the tire wear performance evaluation method according to the present invention, the number of the certain driving conditions may be 50% or less of the number of the plurality of driving conditions.

[0008] The tire wear performance evaluation method of the present invention may include a step of weighting the wear energy of the tire to be evaluated by the occurrence frequency for each of the some of the driving conditions to obtain a total wear energy of the tire to be evaluated, and a step of evaluating the wear performance based on the total wear energy of the tire to be evaluated.

[0009] In the tire wear performance evaluation method of the present invention, the some driving conditions may include the driving conditions, and the evaluating step may evaluate the wear performance of tires mounted on the driving wheels of the vehicle.

[0010] In the tire wear performance evaluation method of the present invention, the some of the driving conditions may include at least one of the driving conditions of free rolling and braking, and the evaluating step may evaluate the wear performance of tires mounted on driven wheels of the vehicle.

[0011] The present invention is an apparatus having a calculation processing device for evaluating the wear performance of a tire tread portion, wherein the calculation processing device includes an occurrence frequency acquisition unit that drives a vehicle equipped with a tire under a plurality of driving conditions including free rolling, braking, driving, and cornering, and acquires the occurrence frequency of each of the plurality of driving conditions; a wear energy calculation unit that calculates the wear energy of the tread portion for each of the plurality of driving conditions; a first total wear energy calculation unit that weights the wear energy for each of the plurality of driving conditions by the occurrence frequency to obtain a total wear energy taking into account all of the plurality of driving conditions; a driving condition determination unit that determines a portion of driving conditions selected from the plurality of driving conditions; and an occurrence frequency determination unit that determines the occurrence frequency of the portion of driving conditions by multiple regression analysis based on the wear energy corresponding to the portion of driving conditions and the total wear energy. Effect of the Invention

[0012] By adopting the above steps, the tire wear performance evaluation method of the present invention makes it possible to maintain the evaluation accuracy of the wear performance while shortening the time required to evaluate the wear performance of a tire. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing an example of a computer (tire wear performance evaluation device) that executes a tire wear performance evaluation method. [Diagram 2] 2 is a flowchart showing an example of a processing procedure of a tire wear performance evaluation method. [Diagram 3] 13 is a flowchart showing an example of a processing procedure of an occurrence frequency obtaining step. [Figure 4] 1 is a graph showing an example of occurrence frequencies of a plurality of driving conditions. [Diagram 5] FIG. 2 is a perspective view showing an example of a tire model and a road surface model. [Figure 6] 13 is a flowchart showing an example of a processing procedure of an occurrence frequency determination step. [Figure 7]1 is a graph showing an example of occurrence frequencies of some driving conditions. [Figure 8] 13 is a flowchart showing an example of a processing procedure of an evaluated wear energy acquisition step. [Figure 9] FIG. 2 is a conceptual diagram showing the total wear energy of a tire to be evaluated. [Figure 10] 1 is a graph showing the relationship between the total wear energy of an example and the total wear energy of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are intended to enhance understanding of the contents of the invention, and therefore some of the drawings may be exaggerated, and the scales of the drawings may not be strictly consistent.

[0015] [Tire wear performance evaluation method (first embodiment)] In the tire wear performance evaluation method of this embodiment (hereinafter sometimes simply referred to as the "evaluation method"), the wear performance of a tire tread portion is evaluated. In this embodiment, the evaluation method is executed using a computer. FIG. 1 is a block diagram showing an example of a computer (tire wear performance evaluation device) that executes the tire wear performance evaluation method.

[0016] [Tire wear performance evaluation device] The computer 1 of this embodiment is configured as a tire wear performance evaluation device (hereinafter, may be simply referred to as an "evaluation device") 1A. The computer 1 of this embodiment is configured to include an input unit 2 as an input device, an output unit 3 as an output device, and a calculation processing device 4 that calculates physical quantities and the like of the tire.

[0017] The input unit 2 may be, for example, a keyboard or a mouse. The output unit 3 may be, for example, a display device or a printer. The arithmetic processing device 4 includes a calculation unit (CPU) 4A that performs various calculations, a storage unit 4B that stores data, programs, etc., and a working memory 4C.

[0018] The storage unit 4B is a non-volatile information storage device formed of, for example, a magnetic disk, an optical disk, an SSD, etc. The storage unit 4B includes a data section 5 and a program section 6.

[0019] The data section 5 is for storing information necessary for executing the evaluation method, calculation results obtained by executing the evaluation method, and the like. The data section 5 of this embodiment includes a driving history input section 5A in which the driving history of the vehicle is stored, and a model input section 5B in which a tire model and a road surface model are stored. The data section 5 includes an occurrence frequency input section 5C for inputting the occurrence frequency of driving conditions, and a wear energy input section 5D for inputting wear energy. The data section 5 includes a total wear energy input section 5E for inputting the total wear energy, and a partial driving condition input section 5F for inputting some driving conditions.

[0020] The program section 6 is a program executed by the calculation section 4A. The program section 6 of this embodiment includes an occurrence frequency acquisition section 6A, a wear energy calculation section 6B, a first total wear energy calculation section 6C, a driving condition determination section 6D, an occurrence frequency determination section 6E, a second total wear energy calculation section 6F, and an evaluation section 6G. The functions of these programs will be described in each step of the evaluation method described later.

[0021] [Obtain the occurrence frequency of multiple driving conditions (Obtain occurrence frequency step S1)] 2 is a flowchart showing an example of a processing procedure of a tire wear performance evaluation method. In the evaluation method of this embodiment, first, occurrence frequencies of a plurality of driving conditions (including free rolling, braking, driving, and cornering) are acquired for a vehicle equipped with a tire (occurrence frequency acquisition step S1).

[0022] In the occurrence frequency acquisition step S1 of this embodiment, for example, the occurrence frequency of driving conditions is acquired for a vehicle in a destination where various tires are used. Therefore, in the occurrence frequency acquisition step S1, the tires mounted on the vehicle are not limited to tires whose wear performance is evaluated. In addition, the vehicle is exemplified as, for example, a passenger car, but is not particularly limited, and may be, for example, a truck or a bus. FIG. 3 is a flowchart showing an example of the processing procedure of the occurrence frequency acquisition step S1.

[0023] [Acquisition of driving history (step S11)] In the occurrence frequency acquisition step S1 of this embodiment, first, a driving history when a vehicle equipped with the tire is driven under a plurality of driving conditions is acquired (step S11). The plurality of driving conditions include a free rolling driving condition, a braking driving condition, a driving driving condition, and a turning driving condition. The turning driving conditions include a left turning driving condition and a right turning driving condition.

[0024] The driving history (not shown) of this embodiment is acquired by driving the vehicle on routes including, for example, highways, mountain roads, and general roads. On these routes, the vehicle can be driven under a plurality of driving conditions including free rolling, braking, driving, and turning.

[0025] The driving history of this embodiment includes a plurality of accelerations when the vehicle is driven under a plurality of driving conditions. These accelerations are measured at predetermined intervals (e.g., every 5 to 15 m of driving distance) using an accelerometer mounted on the vehicle.

[0026] The acceleration includes, for example, the acceleration in the forward / rearward direction of the vehicle, the acceleration in the left / right direction of the vehicle, etc. Based on these accelerations, a plurality of driving conditions (free rolling, braking, driving, and turning driving conditions) at the time when the acceleration was measured can be respectively specified. The driving history (time series data of acceleration) is input to the driving history input unit 5A (shown in FIG. 1).

[0027] [Obtain the occurrence frequency of multiple driving conditions] Next, in the occurrence frequency acquisition step S1 of this embodiment, the occurrence frequency of each of a plurality of driving conditions is acquired using the vehicle's driving history (not shown) (step S12). In step S12 of this embodiment, the occurrence frequency of each of a plurality of driving conditions is acquired using the computer 1 (evaluation device 1A) shown in FIG.

[0028] In step S12 of this embodiment, the driving history previously input to the driving history input unit 5A shown in FIG. 1 and the occurrence frequency acquisition unit 6A of the program unit 6 are input to the working memory 4C. The occurrence frequency acquisition unit 6A is for acquiring the occurrence frequency of each of a plurality of driving conditions. The occurrence frequency acquisition unit 6A is executed by the calculation unit 4A. FIG. 4 is a graph showing an example of the occurrence frequency of a plurality of driving conditions. In FIG. 4, the magnitude of the frequency is indicated by the size of the arc, and the larger the arc, the higher the frequency.

[0029] In step S12 of this embodiment, first, the acceleration of free rolling, the acceleration of braking, the acceleration of driving, and the acceleration of turning (left turning and right turning) are identified from the multiple accelerations (forward / backward acceleration, left / right acceleration, etc.) included in the driving history. Then, in step S12, the occurrence frequency (measurement frequency) of these accelerations is tallied. As a result, in step S12, the occurrence frequency of each of the multiple driving conditions (in this example, the acceleration of free rolling, the acceleration of braking, the acceleration of driving, and the acceleration of turning) is obtained.

[0030] The acceleration of free rolling is 0G in both the front-rear and left-right directions. The braking accelerations in this embodiment include, for example, rearward accelerations β1G and β2G. The driving accelerations in this embodiment include, for example, forward accelerations α1G and α2G. Note that α1, α2, β1, and β2 are all numerical values ​​indicating accelerations, and differ depending on the vehicle in its destination.

[0031] In this embodiment, the accelerations for turning left include, for example, accelerations δ1G and δ2G in the left direction. In this embodiment, the accelerations for turning right include, for example, accelerations γ1G and γ2G in the right direction. Note that δ1, δ2, γ1, and γ2 are all numerical values ​​indicating accelerations, and differ depending on the vehicle in the destination. In addition, the multiple driving conditions are not limited to such an embodiment, and for example, there may be one each of braking acceleration, driving acceleration, and turning (left turning and right turning) acceleration, or a greater number of accelerations may be included.

[0032] In this embodiment, when multiple driving conditions (e.g., both forward acceleration and leftward acceleration) occur simultaneously, the frequencies of those driving conditions (e.g., each acceleration of driving and left turning) are added (aggregated). Also, in this embodiment, each acceleration may be fractionally processed (rounded) based on a predetermined procedure. As a result, in this embodiment, the measured acceleration can be classified into the above-mentioned accelerations while preventing the number of multiple driving conditions from becoming greater than necessary. The occurrence frequencies of the driving conditions are input to occurrence frequency input unit 5C (shown in FIG. 1).

[0033] [Calculate the wear energy of the tread (Step S2)] Next, as shown in Fig. 2, in the evaluation method of this embodiment, the wear energy of the tread portion is calculated for each of a plurality of driving conditions (step S2). The wear energy of this embodiment is calculated by a tire simulation using the computer 1 (evaluation device 1A) shown in Fig. 1. The wear energy may be obtained, for example, based on an experiment using the tire mounted on the vehicle in the occurrence frequency obtaining step S1.

[0034] In step S2 of this embodiment, first, the tire model and the road surface model stored in the model input unit 5B are read into the working memory 4C. Furthermore, in step S2, the wear energy calculation unit 6B is read into the working memory 4C. The wear energy calculation unit 6B is for calculating the wear energy of the tread portion for each of a plurality of driving conditions. Then, the wear energy calculation unit 6B is executed by the operation unit 4A. FIG. 5 is a perspective view showing an example of the tire model 11 and the road surface model 12.

[0035] The tire model 11 and the road surface model 12 can be created by a known procedure (for example, the procedure described in the above-mentioned Patent Document 1). It is preferable to use the tire model 11 modeled on a tire (not shown) mounted on a vehicle in the occurrence frequency acquisition step S1.

[0036] In step S2 of this embodiment, the tire model 11 is rolled on the road surface model 12 to calculate the wear energy of the tread portion 13. The rolling calculation of the tire model 11 and the wear energy calculation are performed based on a known procedure (for example, the procedure described in the above-mentioned Patent Document 1).

[0037] In step S2 of this embodiment, wear energy is calculated for each of the multiple driving conditions (in this example, the free rolling acceleration, each braking acceleration, each driving acceleration, and each turning acceleration) whose occurrence frequency was acquired in the occurrence frequency acquisition step S1. These wear energies can be calculated by setting the torque and lateral force corresponding to each driving condition in the tire model 11 during the rolling calculation.

[0038] In step S2 of this embodiment, the wear energy when the tire rolls the above interval (unit distance) under each driving condition is calculated. The wear energy may be obtained at any node (not shown) of the elements 14 constituting the tread portion 13 of the tire model 11, or may be obtained at all nodes of the tread portion 13. The wear energy is input to a wear energy input unit 5D (shown in FIG. 1).

[0039] [Get total wear energy (Step S3)] Next, in the evaluation method of this embodiment, the total wear energy is calculated (step S3). The total wear energy is calculated by taking into consideration all of the multiple driving conditions (in this example, the acceleration of free rolling, each acceleration of braking, each acceleration of driving, and each acceleration of turning). In this embodiment, the total wear energy is calculated by weighting the wear energy by the occurrence frequency for each of the multiple driving conditions. In this embodiment, the computer 1 (evaluation device 1A) shown in FIG. 1 is used to obtain the total wear energy.

[0040] In step S3 of this embodiment, first, the occurrence frequency of the driving condition inputted in the occurrence frequency input section 5C (shown in FIG. 4) and the wear energy inputted in the wear energy input section 5D are read into the work memory 4C. Furthermore, the first total wear energy calculation section 6C of the program section 6 is read into the work memory 4C. The first total wear energy calculation section 6C is for obtaining the total wear energy taking into account all of the multiple driving conditions. Then, the first total wear energy calculation section 6C is executed by the calculation section 4A.

[0041] In step S3 of this embodiment, the wear energy is weighted (multiplied) by the occurrence frequency for each of a plurality of driving conditions (in this example, the free rolling acceleration, each braking acceleration, each driving acceleration, and each turning acceleration shown in FIG. 4). Then, the wear energies weighted by the occurrence frequency for all driving conditions are added together. In this way, the total wear energy taking into account all of the plurality of driving conditions is obtained.

[0042] The total wear energy in this embodiment is treated as the sum of the wear energy generated in the tread portion (not shown) of the tire from the start of driving on the above route to the end of driving (the period during which the driving history is acquired). Since such total wear energy takes into account all of the multiple driving conditions, the wear energy generated in the tread portion of the tire that has driven the above route can be calculated with high accuracy. The total wear energy is input to the total wear energy input unit 5E (shown in FIG. 1).

[0043] [Determine some driving conditions (Step S4)] Next, in the evaluation method of this embodiment, some of the driving conditions selected from a plurality of driving conditions (in this example, the acceleration of free rolling, each acceleration of braking, each acceleration of driving, and each acceleration of turning) are determined (step S4). In step S4 of this embodiment, some of the driving conditions are determined using the computer 1 (evaluation device 1A) shown in Fig. 1, but they may also be determined by an operator.

[0044] In step S4 of this embodiment, first, the occurrence frequency of the driving condition inputted to the occurrence frequency input section 5C (shown in FIG. 4) is read into the working memory 4C. Furthermore, the driving condition determination section 6D of the program section 6 is read into the working memory 4C. The driving condition determination section 6D is for determining a part of the driving conditions selected from the plurality of driving conditions. Then, the driving condition determination section 6D is executed by the calculation section 4A.

[0045] Some of the driving conditions can be appropriately selected from a plurality of driving conditions shown in FIG. 4 (in this example, the acceleration of free rolling, each acceleration of braking, each acceleration of driving, and each acceleration of turning).

[0046] However, the wear of tires mounted on the drive wheels of a vehicle tends to be relatively heavily influenced by the drive driving conditions among a plurality of driving conditions. Therefore, in the evaluation method of the present embodiment, for example, when the wear performance of tires mounted on the drive wheels of a vehicle is evaluated, it is desirable that some of the driving conditions include the drive driving conditions.

[0047] Incidentally, the driving driving condition may be one selected from a plurality of driving accelerations. In this embodiment, the acceleration that occurs most frequently among the plurality of driving accelerations shown in Fig. 4 (for example, the forward acceleration α1G) is determined as the partial driving condition. As a result, in this embodiment, the number of partial driving conditions can be reduced, and therefore the calculation time can be shortened in the step of calculating the total wear energy of the tire to be evaluated (evaluated wear energy acquisition step S6) described later.

[0048] Furthermore, the wear of the tires of the drive wheels tends to be relatively more affected by the driving conditions of turning (left turning and right turning) among the multiple driving conditions shown in Fig. 4. For this reason, in the evaluation method of this embodiment, for example, when the wear performance of tires mounted on the drive wheels of a vehicle is evaluated, the driving conditions of turning may be further included in the part of the driving conditions.

[0049] The driving condition for turning left may be selected from the multiple left-turn accelerations shown in Fig. 4. In this embodiment, the acceleration that occurs most frequently (for example, the leftward acceleration δ2G) among the multiple left-turn accelerations is determined as a part of the driving conditions.

[0050] Similarly, the driving condition for turning right may be selected from the multiple right turning accelerations shown in Fig. 4. In this embodiment, the acceleration that occurs most frequently among the multiple right turning accelerations (for example, the rightward acceleration γ2G) is determined as a part of the driving conditions.

[0051] In this manner, the partial driving conditions in this embodiment are selected from a plurality of accelerations for left turns and a plurality of accelerations for right turns, one each. Therefore, in this embodiment, the number of partial driving conditions can be reduced, and therefore the calculation time can be shortened in the step of obtaining the total wear energy of the tire to be evaluated (step S6 of obtaining the evaluated wear energy), which will be described later.

[0052] On the other hand, the wear of tires mounted on driven wheels of a vehicle is relatively more affected by the free rolling and braking driving conditions among the multiple driving conditions shown in Fig. 4. For this reason, in the evaluation method of this embodiment, for example, when the wear performance of tires mounted on driven wheels of a vehicle is evaluated, it is desirable that some of the driving conditions include the free rolling and braking driving conditions. Note that the braking driving condition may be selected from multiple braking accelerations (for example, the acceleration that occurs most frequently among multiple braking accelerations).

[0053] In the evaluation method of this embodiment, the wear performance of tires mounted on the driving wheels of a vehicle is evaluated. For this reason, as some of the driving conditions of this embodiment, the driving conditions of driving and turning (left turning and right turning) are determined from among the multiple driving conditions shown in Fig. 4 based on the above-mentioned procedure. The part of the driving conditions is stored in the part of driving condition input unit 5F.

[0054] [Determine the occurrence frequency of some driving conditions (occurrence frequency determination step S5)] Next, in the evaluation method of this embodiment, the occurrence frequency of the partial driving condition is determined by multiple regression analysis based on the wear energy corresponding to the partial driving condition and the total wear energy (occurrence frequency determination step S5). In the occurrence frequency determination step S5 of this embodiment, the occurrence frequency of the partial driving condition is determined using the computer 1 (evaluation device 1A) shown in FIG.

[0055] In the occurrence frequency determination step S5 of this embodiment, first, the wear energy inputted in the wear energy input section 5D and some of the driving conditions inputted in the partial driving condition input section 5F are read into the work memory 4C. Furthermore, in the occurrence frequency determination step S5, the total wear energy inputted in the total wear energy input section 5E and the occurrence frequency determination section 6E of the program section 6 are read into the work memory 4C. The occurrence frequency determination section 6E is for determining the occurrence frequency of some of the driving conditions. Then, the occurrence frequency determination section 6E is executed by the calculation section 4A. FIG. 6 is a flowchart showing an example of the processing procedure of the occurrence frequency determination step S5.

[0056] [Identifying wear energy under certain driving conditions (step S51)] In the occurrence frequency determination step S5 of this embodiment, first, wear energy corresponding to some of the driving conditions is specified (step S51). In step S51, wear energy corresponding to some of the driving conditions is selected from among the wear energies acquired for the multiple driving conditions (in this example, the acceleration of free rolling, each acceleration of braking, each acceleration of driving, and each acceleration of turning) in the above-mentioned step S2.

[0057] Some of the driving conditions in this embodiment include the driving condition (forward acceleration α1G), the left turning driving condition (left turning acceleration δ2G), and the right turning driving condition (right turning acceleration γ2G) among the multiple driving conditions shown in Fig. 4. Therefore, in step S51, wear energy corresponding to some of these driving conditions is identified among the wear energies of the multiple driving conditions acquired in the above-mentioned step S2.

[0058] [Perform multiple regression analysis (Step S52)] Next, in the occurrence frequency determination step S5 of this embodiment, a multiple regression analysis is performed based on the wear energy corresponding to some of the driving conditions and the total wear energy (step S52).

[0059] The relationship between the total wear energy, the wear energy corresponding to a certain driving condition, and the occurrence frequency of the certain driving condition can be defined, for example, by the following formula (1). E=E1×F1+E2×F2+E3×F3 … (1) Here, the variables are as follows: E: Total wear energy E1: Wear energy of drive under running conditions E2: Wear energy under left turning driving conditions E3: Wear energy under right-turn driving conditions F1: Frequency of occurrence of driving conditions F2: Frequency of occurrence of left-turn driving conditions F3: Frequency of occurrence of right-turn driving conditions

[0060] The above formula (1) indicates that under each driving condition, the wear energy value E1 to E3 obtained by adding up values ​​weighted by the occurrence frequencies F1 to F3 is equal to the total wear energy E taking into account all of the multiple driving conditions.

[0061] The total wear energy obtained in step S3 is substituted for the total wear energy E. The wear energies E1 to E3 for each driving condition are substituted for the wear energy determined in step S51. Note that the occurrence frequencies F1 to F3 are each determined by multiple regression analysis, and are different (independent) from the occurrence frequency acquired in the occurrence frequency acquisition step S1.

[0062] In step S52 of this embodiment, the occurrence frequencies F1-F3 of some driving conditions are determined by multiple regression analysis based on the wear energies E1-E3 corresponding to some driving conditions and the total wear energy E using the above formula (1). For the multiple regression analysis, for example, StatWorks manufactured by Nikkei Science and Technology Corporation is used. Fig. 7 is a graph showing an example of the occurrence frequency of some driving conditions. In Fig. 7, the magnitude of the frequency is indicated by the size of the arc, and the larger the arc, the higher the frequency.

[0063] In step S52 of this embodiment, the occurrence frequencies of the multiple driving conditions (free rolling, braking, driving, and turning acceleration) shown in Fig. 4 can be consolidated into occurrence frequencies F1 to F3 of some of the driving conditions shown in Fig. 7. The occurrence frequencies F1 to F3 of some of the driving conditions are input to the occurrence frequency input unit 5C (shown in Fig. 1).

[0064] [Acquire the total wear energy of the tire to be evaluated (Evaluation wear energy acquisition step S6)] Next, as shown in Fig. 2, in the evaluation method of this embodiment, the total wear energy of the tire to be evaluated is obtained (evaluation wear energy acquisition step S6). In this embodiment, the total wear energy of the tire to be evaluated is calculated by simulating the tire using the computer 1 (evaluation device 1A) shown in Fig. 1.

[0065] In the evaluated wear energy acquisition step S6 of this embodiment, first, a tire model (not shown) that models the tire to be evaluated and stored in the model input unit 5B, and a road surface model 12 (shown in FIG. 5) are read into the working memory 4C. Furthermore, in the evaluated wear energy acquisition step S6, occurrence frequencies F1 to F3 (shown in FIG. 7) of some driving conditions inputted into the occurrence frequency input unit 5C, and a second total wear energy calculation unit 6F are read into the working memory 4C. The second total wear energy calculation unit 6F is for obtaining the total wear energy of the tire to be evaluated. Then, the second total wear energy calculation unit 6F is executed by the operation unit 4A. FIG. 8 is a flowchart showing an example of the processing procedure of the evaluated wear energy acquisition step S6.

[0066] [Acquire the wear energy of the tire to be evaluated (Step S61)] In the evaluation wear energy acquisition step S6 of this embodiment, first, the wear energy of the tire to be evaluated is acquired for each of some driving conditions (step S61). As shown in Fig. 7, the some driving conditions of this embodiment include a driving condition (driving (forward) acceleration α1G), a left turning driving condition (left turning (left direction) acceleration δ2G), and a right turning driving condition (right turning (right direction) acceleration γ2G).

[0067] In this embodiment, a tire model (not shown) that models the tire to be evaluated, and a road surface model 12 (shown in FIG. 5) are created based on a known procedure (for example, the procedure described in the above-mentioned Patent Document 1). In step S61, it is preferable to use design factors of the tire to be evaluated for tire modeling.

[0068] Next, in step S61 of this embodiment, the tire model to be evaluated is rolled on the road surface model 12, and the wear energy of the tire to be evaluated is calculated for each of some driving conditions. The rolling calculation of the tire model to be evaluated (not shown) and the wear energy calculation are performed based on a known procedure (for example, the procedure described in the above-mentioned Patent Document 1).

[0069] In step S61 of this embodiment, the wear energy of the tire to be evaluated is calculated for each of some driving conditions (driving condition (acceleration α1G), left turning driving condition (acceleration δ2G), and right turning driving condition (acceleration γ2G)). These wear energies can be calculated by setting the torque and lateral force corresponding to each driving condition in a tire model (not shown) during the rolling calculation.

[0070] In step S61 of this embodiment, the wear energy when the tire rolls the above interval (unit distance) is calculated for each driving condition. The wear energy may be calculated at any node (not shown) of the tread of the tire model (not shown) to be evaluated, or may be calculated at all nodes of the tread. The wear energy for some driving conditions is input to the wear energy input unit 5D.

[0071] [Calculation of the total wear energy of the tire to be evaluated (Step S62)] Next, in the evaluated wear energy acquisition step S6 of this embodiment, the wear energy of the tire to be evaluated is weighted by the occurrence frequencies F1 to F3 for each of some driving conditions, and the total wear energy of the tire to be evaluated is calculated (step S62).

[0072] In this embodiment, the wear energy of the tire to be evaluated is weighted (multiplied) by the occurrence frequencies F1 to F3 for each of the driving conditions (driving conditions (acceleration α1G), left-turn driving conditions (acceleration δ2G), and right-turn driving conditions (acceleration γ2G)). Then, the wear energies weighted by the occurrence frequencies F1 to F3 for all of the driving conditions are added together to determine the total wear energy of the tire to be evaluated.

[0073] Fig. 9 is a conceptual diagram showing the total wear energy of a tire to be evaluated. In Fig. 9, the total wear energy is calculated at all nodes of the tread portion of a tire model (not shown) to be evaluated. In Fig. 9, the magnitude of the total wear energy is indicated by the shade of color, and the darker the color, the greater the total wear energy. The total wear energy of the tire to be evaluated is input to a total wear energy input unit 5E (shown in Fig. 1).

[0074] As described above, the occurrence frequencies F1 to F3 (shown in FIG. 7) of some driving conditions are determined by multiple regression analysis based on the total wear energy taking into consideration all of the multiple driving conditions shown in FIG. 4 (in this example, the accelerations of free rolling, braking, driving, and turning). Therefore, the occurrence frequencies F1 to F3 are an aggregate of the occurrence frequencies of the multiple driving conditions (the accelerations of free rolling, braking, driving, and turning). Therefore, the total wear energy taking into consideration these occurrence frequencies F1 to F3 can approximate, for example, the total wear energy of the tire to be evaluated taking into consideration all of the multiple driving conditions (shown in FIG. 4). As a result, the evaluation method of this embodiment can maintain the evaluation accuracy of wear performance.

[0075] Furthermore, in the evaluation method of this embodiment, the number of some driving conditions (shown in FIG. 7) can be made smaller than the number of the multiple driving conditions (shown in FIG. 4). As a result, in this embodiment, unlike conventional methods (e.g., Patent Document 1) that use the occurrence frequency of multiple driving conditions (use conditions), it is not necessary to obtain the wear energy of the tire to be evaluated in driving conditions (e.g., each acceleration during braking) other than the some driving conditions. Therefore, in this embodiment, the time required for evaluation can be shortened.

[0076] In order to shorten the time required for the evaluation, the number of the partial driving conditions is preferably 50% or less of the number of the multiple driving conditions, more preferably 35% or less, while in order to maintain the evaluation accuracy of the wear performance, the number of the partial driving conditions is preferably 10% or more of the number of the multiple driving conditions, more preferably 15% or more.

[0077] [Evaluate tire wear performance (Step S7)] Next, as shown in Fig. 2, in the evaluation method of this embodiment, the wear performance of the tire to be evaluated is evaluated based on the total wear energy of the tire to be evaluated (step S7). In step S7 of this embodiment, the wear performance is evaluated using the computer 1 (evaluation device 1A) shown in Fig. 1, but it may also be evaluated by an operator.

[0078] In step S7 of this embodiment, first, the total wear energy of the tire to be evaluated, which is input to the total wear energy input unit 5E, is read into the working memory 4C. Furthermore, the evaluation unit 6G of the program unit 6 is read into the working memory 4C. The evaluation unit 6G is for evaluating the wear performance of the tire to be evaluated. Then, the evaluation unit 6G is executed by the calculation unit 4A.

[0079] In step S7 of the present embodiment, it is determined whether the total wear energy of the tire to be evaluated is within an allowable range. The allowable range is appropriately set based on the category, structure, etc. of the tire to be evaluated.

[0080] In this embodiment, the wear performance of a tire mounted on a driving wheel of a vehicle is evaluated. As described above, some driving conditions (shown in FIG. 7) taken into consideration in the calculation of the total wear energy include the driving driving condition among the multiple driving conditions (shown in FIG. 4). Therefore, in this embodiment, the total wear energy of the tire to be evaluated mounted on the driving wheel can be calculated with high accuracy.

[0081] Furthermore, some of the driving conditions (shown in FIG. 7) include the driving conditions (shown in FIG. 4) of turning (left turning and right turning) among the multiple driving conditions. Therefore, the total wear energy of the tire to be evaluated that is mounted on the driving wheels can be calculated with higher accuracy. Therefore, the evaluation method of this embodiment can accurately evaluate the wear performance of the tire to be evaluated.

[0082] If it is determined in step S7 that the total wear energy is within the allowable range ("Yes" in step S7), a tire is designed and manufactured based on the design factors of the tire to be evaluated (step S8).

[0083] On the other hand, if it is determined that the total wear energy is outside the allowable range ("No" in step S7), the design factors of the tire to be evaluated are changed (step S9), and the evaluated wear energy acquisition step S6 and step S7 are performed again. In this way, the evaluation method of this embodiment can reliably design and manufacture a tire with excellent wear resistance.

[0084] [Method for evaluating tire wear performance (second embodiment)] In the evaluation method of this embodiment, the wear performance of a tire mounted on a driving wheel of a vehicle is evaluated, but the present invention is not limited to this embodiment, and the wear performance of a tire mounted on a driven wheel of a vehicle may be evaluated. In this case, as described above, it is preferable that the part of the driving conditions taken into consideration in the calculation of the total wear energy includes the free rolling and braking driving conditions among the multiple driving conditions (shown in FIG. 4). As a result, in the evaluation method of this embodiment, the total wear energy of the tire to be evaluated that is mounted on the driven wheel can be calculated with higher accuracy, and the wear performance of the tire to be evaluated can be evaluated with higher accuracy.

[0085] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified in various ways. EXAMPLES

[0086] Based on the procedure shown in FIG. 2, the wear performance of eight types of tires having different tire patterns and profiles was evaluated (Examples).

[0087] In the embodiment, first, a vehicle equipped with the tire was driven for a total of about 20,000 km on ordinary roads and expressways, and a driving history was obtained when the vehicle was driven under a plurality of driving conditions including free rolling, braking, driving, and turning, based on the processing procedure shown in Fig. 3. Then, the occurrence frequency of each of the plurality of driving conditions was obtained using the vehicle's driving history, as shown in Fig. 4.

[0088] Next, in the embodiment, a step of calculating the wear energy of the tread portion for each of a plurality of driving conditions, and a step of weighting the wear energy by the occurrence frequency to obtain a total wear energy taking into consideration all of the plurality of driving conditions were performed. Next, in the embodiment, a step of determining some driving conditions selected from the plurality of driving conditions, and a step of determining the occurrence frequency of the some driving conditions (shown in FIG. 7) based on the processing procedure shown in FIG. 6 were performed.

[0089] In the embodiment, the wear energy of the tires being evaluated (8 types) was calculated for each of a certain number of driving conditions, and the wear energies were weighted by their occurrence frequency to calculate the total wear energy of each of the tires being evaluated (8 types).

[0090] For comparison, the wear energy of the tires evaluated (8 types) was calculated for each of a number of driving conditions, and the wear energy was weighted by occurrence frequency to calculate the total wear energy of the tires evaluated (8 types) (Comparative Example). The common specifications are as follows: Tire size: 195 / 65R15 Internal pressure: 240kPa Load: 3780N Tires to be evaluated: Drive wheels of vehicle

[0091] Fig. 10 is a graph showing the relationship between the total wear energy of the Example and the total wear energy of the Comparative Example. Fig. 10 shows the correlation between the total wear energy of the Example and the total wear energy of the Comparative Example at the same position of each land portion (center land portion, pair of middle land portions, and pair of shoulder land portions) of eight types of tires to be evaluated.

[0092] As shown in FIG. 10, the correlation between the total wear energy of the embodiment and the total wear energy of the comparative example is high (coefficient of determination R 2Therefore, the embodiment was able to obtain substantially the same total wear energy as the comparative example, which takes into account the occurrence frequency of a plurality of driving conditions, and was able to maintain the evaluation accuracy of the wear performance.

[0093] Furthermore, in the examples, unlike the comparative examples, it is not necessary to calculate the wear energy of the tire being evaluated for each of multiple driving conditions, and therefore the time required to evaluate the wear performance of the tire can be shortened (to approximately 1 / 3 of that in the comparative examples). [Explanation of symbols]

[0094] S1: A step of acquiring occurrence frequencies of a plurality of driving conditions S2 Step of calculating wear energy for each of multiple driving conditions S3 Step to calculate total wear energy considering multiple driving conditions S4: determining a part of driving conditions from a plurality of driving conditions S5 Step for determining the frequency of occurrence of certain driving conditions

Claims

1. 1. A method for evaluating tire tread wear performance, comprising: A step of running a vehicle equipped with the tire under a plurality of running conditions including free rolling, braking, driving, and cornering, and acquiring occurrence frequencies of the plurality of running conditions; calculating a wear energy of the tread portion for each of the plurality of driving conditions; weighting the wear energy by the occurrence frequency for each of the plurality of driving conditions to obtain a total wear energy taking into account all of the plurality of driving conditions; determining a part of driving conditions selected from the plurality of driving conditions; and determining an occurrence frequency of the partial driving condition by multiple regression analysis based on the wear energy corresponding to the partial driving condition and the total wear energy. Method for evaluating tire wear performance.

2. The method for evaluating tire wear performance according to claim 1 , wherein the number of the certain driving conditions is 50% or less of the number of the plurality of driving conditions.

3. weighting the wear energy of the tire to be evaluated by the occurrence frequency for each of the driving conditions to obtain a total wear energy of the tire to be evaluated; The method for evaluating tire wear performance according to claim 1 or 2, further comprising: evaluating wear performance based on a total wear energy of the tire to be evaluated.

4. The part of driving conditions includes the driving condition of the drive, The tire wear performance evaluation method according to claim 3 , wherein the evaluating step evaluates the wear performance of tires mounted on driving wheels of the vehicle.

5. The part of running conditions includes at least one of the free rolling and braking running conditions, 5. The tire wear performance evaluation method according to claim 3, wherein the evaluating step evaluates the wear performance of tires mounted on driven wheels of the vehicle.

6. An apparatus having a processing device for evaluating the wear performance of a tire tread portion, The arithmetic processing device includes: an occurrence frequency acquisition unit that causes a vehicle equipped with the tire to travel under a plurality of travel conditions including free rolling, braking, driving, and turning, and acquires occurrence frequencies of the plurality of travel conditions; a wear energy calculation unit that calculates a wear energy of the tread portion for each of the plurality of driving conditions; a first total wear energy calculation unit that calculates a total wear energy taking into account all of the plurality of driving conditions by weighting the wear energy by the occurrence frequency for each of the plurality of driving conditions; A driving condition determination unit that determines a part of driving conditions selected from the plurality of driving conditions; and an occurrence frequency determination unit that determines an occurrence frequency of the partial driving condition by multiple regression analysis based on the wear energy corresponding to the partial driving condition and the total wear energy. Tire wear performance evaluation device.

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