How to evaluate wandering performance

Abstract

To provide an evaluation method that can evaluate wandering performance of a tire quantitatively.SOLUTION: An evaluation method for evaluating wandering performance of tires 2 running on a rutted road surface R having ruts r formed thereon includes: a running step S1 of making a vehicle 1 mounted with the tires 2 run so that the tires 2 pass on the ruts r on the rutted road surface R; a measuring step S2 of measuring a steering angle A and steering torque T of the vehicle 1 in the running step S1 time-serially; and an evaluating step S4 of evaluating wandering performance of the tires 2, on the basis of time-series data D on at least either of the steering angle A and the steering torque T measured in the measuring step S2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for evaluating the wandering performance of a tire when traveling on a rutted road surface. [Background technology]

[0002] Conventionally, attention has been paid to the wandering performance of tires when traveling on rutted road surfaces. For example, the following Patent Document 1 proposes a pneumatic tire that improves wandering performance while suppressing shoulder wear. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-111360 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the wandering performance in Patent Document 1 is evaluated by the driver's sensory evaluation, and a quantitative evaluation method for wandering performance has been desired in order to perform a more objective evaluation.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a method for quantitatively evaluating the wandering performance of a tire. [Means for solving the problem]

[0006] The present invention is a method for evaluating the wandering performance of a tire when traveling on a rutted road surface on which ruts have been formed, and is characterized in that it includes a driving step of driving a vehicle equipped with the tire on the rutted road surface so that the tire passes through the ruts, a measuring step of measuring the steering angle and steering torque of the vehicle during the driving step in a time series manner, and an evaluation step of evaluating the wandering performance of the tire based on time series data of at least one of the steering angle and the steering torque measured in the measuring step.

[0007] In the wandering performance evaluation method of the present invention, it is desirable that the evaluation step evaluates the wandering performance of the tire based on at least one of the maximum absolute value of the time series data of the steering angle and the maximum absolute value of the time series data of the steering torque.

[0008] In the wandering performance evaluation method of the present invention, it is desirable that the evaluation step evaluates the tire's wandering performance as being better the smaller the maximum value of the steering angle or the maximum value of the steering torque generated by the reaction force from the rutted road surface.

[0009] In the wandering performance evaluation method of the present invention, it is preferable that the measuring step further measures the running speed and longitudinal acceleration of the vehicle.

[0010] In the wandering performance evaluation method of the present invention, the traveling step preferably includes an approaching step of making the vehicle approach the wheel rut obliquely.

[0011] In the wandering performance evaluation method of the present invention, the driving step preferably includes a non-steering step of driving the vehicle without applying resistance to a reaction force from the rutted road surface after the vehicle has entered the rut.

[0012] In the wandering performance evaluation method of the present invention, the driving step preferably includes a deceleration step of decelerating the vehicle after the vehicle has entered the rut.

[0013] In the method for evaluating wandering performance of the present invention, the deceleration acceleration in the deceleration step is 1 to 2 m / s 2 It is desirable that:

[0014] In the method for evaluating wandering performance of the present invention, it is preferable that the rutted road surface has a width of 3.5 m or more, a length of 40 m or more, and a depth of the ruts of 15 to 100 mm. Effect of the Invention

[0015] The wandering performance evaluation method of the present invention includes a driving process in which a vehicle equipped with tires is driven on a rutted road surface so that the tires pass through the ruts, a measurement process in which the steering angle and steering torque of the vehicle during the driving process are measured in time series, and an evaluation process in which the wandering performance of the tire is evaluated based on time series data of at least one of the steering angle and the steering torque measured in the measurement process.

[0016] In such a method for evaluating wandering performance, the wandering performance of a tire can be evaluated based on time series data of at least one of the steering angle and the steering torque, without relying on the sensory judgment of a test driver, by driving the tire so as to pass through ruts. Therefore, the method for evaluating wandering performance of the present invention can quantitatively evaluate the wandering performance of a tire. [Brief description of the drawings]

[0017] [Figure 1] 1 is a flowchart showing an embodiment of a method for evaluating wandering performance of the present invention. [Diagram 2] FIG. [Diagram 3] 13 is a flowchart of a traveling process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a flow chart showing the method for evaluating wandering performance of this embodiment, and Fig. 2 is a schematic diagram showing a traveling step S1. As shown in Fig. 1 and Fig. 2, the method for evaluating wandering performance of this embodiment is a method for evaluating the wandering performance of a tire 2 when traveling on a rutted road surface R on which ruts r are formed.

[0019] The method for evaluating wandering performance according to the present embodiment first includes a driving step S1 in which the vehicle 1 equipped with the tire 2 is driven on a rutted road surface R. In the driving step S1, it is preferable to drive the tire 2 so that it passes through the rut r. Such a driving step S1 has excellent reproducibility because the vehicle 1 can be driven in a predetermined mode.

[0020] The wandering performance evaluation method of this embodiment includes a measurement process S2 in which the steering angle A and steering torque T of the vehicle 1 in the traveling process S1 are measured in time series. The measurement process S2 is performed, for example, by a measuring device 3 mounted on the vehicle 1. Such a measurement process S2 can measure time series data D of the steering angle A and steering torque T of the vehicle 1.

[0021] The method for evaluating wandering performance in this embodiment includes an evaluation step S4 for evaluating the wandering performance of the tire 2 based on time-series data D of at least one of the steering angle A and the steering torque T measured in the measurement step S2.

[0022] In such a method for evaluating the wandering performance, the tire 2 is driven so as to pass through the ruts r, and the wandering performance of the tire 2 can be evaluated based on the time-series data D of at least one of the steering angle A and the steering torque T, without relying on the sensory judgment of the test driver. Therefore, the method for evaluating the wandering performance of the present embodiment can quantitatively evaluate the wandering performance of the tire 2.

[0023] In a more preferred embodiment, the wandering performance evaluation method includes a judgment step S3 for judging whether to repeat the traveling step S1 and the measuring step S2 to perform additional measurements before the evaluation step S4. This wandering performance evaluation method can improve the accuracy of the evaluation in the evaluation step S4 by repeating the traveling step S1 and the measuring step S2 multiple times.

[0024] It is desirable that the width W of the rutted road surface R is 3.5 m or more. It is also desirable that the length L of the rutted road surface R is 40 m or more. Such a rutted road surface R can ensure a sufficient driving distance and improve the evaluation accuracy of the wandering performance.

[0025] The depth d of the rut r is preferably 15 to 100 mm. The depth d of the rut r is desirably set in advance based on the traveling speed v of the vehicle 1 within a range in which the rut r formed on the actual road surface affects the traveling of the vehicle 1. Such a rut road surface R can reproduce the rut r formed on the actual road surface, and can improve the evaluation accuracy of the wandering performance. In this specification, the "actual road surface" does not mean a test road surface, but a road surface on which the rut r is formed by the traveling of an ordinary vehicle on an ordinary road or an expressway, including an intersection entrance part where the rut r is likely to be formed.

[0026] Fig. 3 is a flowchart of the traveling step S1. As shown in Fig. 2 and Fig. 3, the traveling step S1 preferably includes an approaching step S11 in which the vehicle 1 is caused to approach the wheel rut r at an angle. Such an approaching step S11 makes it easy to make the vehicle 1 travel so that the tire 2 passes over the wheel rut r reliably.

[0027] In the approaching step S11, for example, the steering device 4 of the vehicle 1 is used to input a steering angle A of 10 to 20°, thereby making the vehicle 1 approach the rut r at an angle. In the approaching step S11, it is desirable to make the vehicle 1 approach the rut road surface R at an angle that crosses the width W over the entire length L of the rut road surface R. In such an approaching step S11, it is easy to make the traveling conditions of the traveling step S1 the same, and the evaluation accuracy of the wandering performance can be improved.

[0028] The approaching step S11 preferably includes a first mode M1 in which the vehicle 1 approaches the wheel track r obliquely from one direction, and a second mode M2 ​​in which the vehicle 1 approaches the wheel track r from the other direction. When the traveling step S1 is repeated multiple times, the approaching step S11 is performed such that the first mode M1 is repeated multiple times and then the second mode M2 ​​is repeated multiple times. Note that the approaching step S11 may be performed, for example, by alternating between the first mode M1 and the second mode M2.

[0029] Such an approach step S11 can evaluate the wandering performance regardless of the approach direction relative to the wheel rut r. The approach step S11 may further include a third mode M3 (not shown) in which the vehicle 1 approaches in a direction along the wheel rut r.

[0030] In the approaching step S11, the traveling speed v of the vehicle 1 when approaching is preferably a constant speed of 30 to 100 km / h, more preferably 30 to 50 km / h. Such an approaching step S11 can accurately reproduce the traveling conditions on an actual road surface.

[0031] The traveling step S1 preferably includes a no-steering step S12 in which, after the vehicle 1 enters the rut r, the vehicle 1 is allowed to travel without applying resistance to the reaction force from the rut road surface R. The no-steering step S12 may be performed, for example, by the test driver lightly placing his / her hands on the steering device 4, or by removing his / her hands from the steering device 4. Such a no-steering step S12 can suppress the influence of the test driver's steering, and can improve the evaluation accuracy of the wandering performance.

[0032] The traveling step S1 preferably includes a deceleration step S13 for decelerating the vehicle 1 after the vehicle 1 enters the rut r. Such a deceleration step S13 can reproduce the traveling of the vehicle 1 traveling on an actual road surface such as an intersection entrance where the rut r is likely to be formed.

[0033] The deceleration acceleration in the deceleration step S13 is preferably 1 to 2 m / s 2In the deceleration step S13, for example, the traveling speed v of the vehicle 1 is decelerated by 10 to 30 km / h when traveling on a rutted road surface R. The deceleration step S13 may be performed, for example, as coasting without operating the acceleration / deceleration device 5 of the vehicle 1. Such a deceleration step S13 can more faithfully reproduce the traveling of the vehicle 1 traveling on an actual road surface, such as when entering an intersection.

[0034] 1 and 2, the measurement step S2 preferably further measures the running speed v and longitudinal acceleration a of the vehicle 1. Such a measurement step S2 can correct the time series data D of the steering angle A and steering torque T with the running speed v and longitudinal acceleration a of the vehicle 1, and can reduce the influence based on the difference between the running speed v and longitudinal acceleration a in the traveling step S1.

[0035] In the measurement process S2, for example, the steering angle A, the steering torque T, the running speed v, and the longitudinal acceleration a are each measured by a sensor of the measurement device 3. The running speed v and the longitudinal acceleration a may be measured by using, for example, a GPS device. In such a measurement process S2, the state of the vehicle 1 in the running process S1 can be measured in a time series manner with high accuracy.

[0036] In the evaluation step S4, it is preferable to evaluate the wandering performance of the tire 2 based on at least one of the maximum value Da1 of the absolute value of the time series data Da of the steering angle A and the maximum value Dt1 of the absolute value of the time series data Dt of the steering torque T. Such an evaluation step S4 can shorten the time required for evaluating the time series data D, and can perform the evaluation in a shorter time.

[0037] In the evaluation step S4, when the no-steering step S12 of the traveling step S1 is performed by lightly placing a hand on the steering device 4, it is desirable to evaluate the wandering performance of the tire 2 based on the maximum value Dt1 of the steering torque T. Since such an evaluation step S4 can be performed using the steering torque T that is less affected even when the steering angle A is affected by the input from the steering device 4, the wandering performance of the tire 2 can be reliably evaluated.

[0038] On the other hand, in the evaluation step S4, when the no-steering step S12 in the traveling step S1 is performed by releasing the steering device 4, it is preferable to evaluate the wandering performance of the tire 2 based on the maximum value Da1 of the steering angle A. Such an evaluation step S4 can evaluate the wandering performance of the tire 2 in detail because the reaction force when the tire 2 passes through the rut r is transmitted as the steering torque T and reflected in the steering angle A.

[0039] In the evaluation step S4 of this embodiment, the smaller the maximum value Da1 of the steering angle A or the maximum value Dt1 of the steering torque T generated by the reaction force from the rutted road surface R, the better the wandering performance of the tire 2 is evaluated. Such an evaluation step S4 can quantitatively evaluate the wandering performance of the tire 2.

[0040] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified in various ways. EXAMPLES

[0041] The wandering performance evaluation method of the embodiment based on Fig. 1 to Fig. 3 was tested for the first tire and the second tire with different specifications. As a comparative example, the first tire and the second tire were tested by the evaluation method based on the sensory evaluation by the test driver. The main common specifications and the test method are as follows.

[0042] <Common specifications> Tire size: 215 / 60R16 Rim size: 16×7J Front tire pressure: 250kPa Rear tire pressure: 250kPa Test vehicle: Medium-sized passenger car Number of passengers: 2 (including test driver)

[0043] <Evaluation method for comparative examples> Five test drivers ran a test vehicle with either the first or second tires on all wheels on a rutted road surface three times, and each test driver evaluated the wandering performance sensorily. The results were shown as the average of each test driver's evaluation on a 10-point scale, with the higher the score, the better the wandering performance.

[0044] <Evaluation Method of the Examples> Test vehicles with either the first or second tires fitted to all wheels were evaluated for wandering performance based on maximum steering angle and maximum steering torque when driven five times on a rutted road surface. The results were shown as the average of the five maximum steering angles and maximum steering torques, with smaller values ​​indicating better wandering performance.

[0045] The results of the test are as follows: 1st tire 2nd tire Sensory evaluation of comparative examples (score) 7 5 Maximum steering angle in the example (°) 33.3 56.4 Maximum torque of the example (N·m) 2.36 2.53

[0046] The test results showed that the first tire had better wandering performance than the second tire in both the comparative example and the example, and confirmed that the wandering performance of tires can be quantitatively evaluated. [Explanation of symbols]

[0047] 1 vehicle 2 Tires

Claims

1. A method for evaluating the wandering performance of a tire when traveling on a rutted road surface, comprising: a running step of running a vehicle equipped with the tire on the rutted road surface so that the tire passes through the ruts; a measuring step of measuring a steering angle and a steering torque of the vehicle in a time series manner during the traveling step; and an evaluation step of evaluating a wandering performance of the tire based on time-series data of at least one of the steering angle and the steering torque measured in the measurement step, The traveling step includes an entry step of causing the vehicle to enter the rut obliquely, In the evaluation step, the tire is evaluated as having better wandering performance as the maximum value of the absolute value of the time series data of the steering angle or the maximum value of the absolute value of the time series data of the steering torque generated by the reaction force from the rutted road surface is smaller. Method for evaluating wandering performance.

2. The wandering performance evaluation method according to claim 1 , wherein the measuring step further measures a traveling speed and a longitudinal acceleration of the vehicle.

3. 3. The method for evaluating wandering performance according to claim 1, wherein the driving step includes a non-steering step of driving the vehicle without applying resistance to a reaction force from a surface of the rutted road after the vehicle has entered the rut.

4. 4. The method for evaluating wandering performance according to claim 1, wherein the driving step includes a deceleration step of decelerating the vehicle after the vehicle enters the rut.

5. The deceleration acceleration in the deceleration step is 1 to 2 m / s ２ The method for evaluating wandering performance according to claim 4, wherein

6. The rutted road surface has a width of 3.5 m or more and a length of 40 m or more; 6. The method for evaluating wandering performance according to claim 1, wherein the depth of the ruts is 15 to 100 mm.

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