Cornering Characteristic Evaluation Method and Flat Belt Test Apparatus

Abstract

To provide a cornering characteristic evaluation method capable of suppressing an effect of movement of a belt in an axial direction.SOLUTION: A method for evaluating cornering characteristics, includes: a first step S1 of rotating a roller to drive a belt at a first speed V1 in a direction perpendicular to an axial direction of the roller; a second step S2 of adding a slip angle SA to a tire running on the belt; a third step S3 of detecting a second speed V2 of the belt moving in the axial direction of the roller with addition of the slip angle SA; a fourth step S4 of calculating a correction angle δSA for correcting the slip angle SA from the first speed V1 and the second speed V2; and a fifth step S5 of using the correction angle δSA to calculate a slip angle SA' after correction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a flat belt testing device and a cornering characteristic evaluation method using the same. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a cornering characteristic evaluation method using a flat belt testing device has been known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4163236 Summary of the Invention [Problem to be solved by the invention]

[0004] When a large slip angle is applied to a tire using a flat belt testing device, the belt of the testing device moves in the axial direction due to the reaction of the cornering force generated by the tire. This axial movement of the belt affects the actual slip angle of the tire relative to the belt, and thus the evaluation of the cornering characteristics. The axial movement of the belt is particularly noticeable in racing tires and heavy-duty tires that generate large cornering forces.

[0005] The present disclosure has been devised in consideration of the above-described circumstances, and has as its main object to provide a flat belt testing device and a cornering characteristic evaluation method that can suppress the effects of axial movement of the belt. [Means for solving the problem]

[0006] The present disclosure provides a method for evaluating cornering characteristics of a tire using a flat belt testing device including a pair of rollers arranged in parallel and an endless belt wound around the pair of rollers, A first step of rotating the roller to drive the belt in a direction perpendicular to the axial direction of the roller at a predetermined first speed V1; A second step of applying a slip angle SA to the tire traveling on the belt; A third step of detecting a second speed V2 of the belt moving in the axial direction of the roller as the slip angle SA is applied; A fourth step of calculating a correction angle δSA for correcting the slip angle SA from the first speed V1 and the second speed V2; A fifth step of calculating a corrected slip angle SA' using the correction angle δSA, which is a cornering characteristic evaluation method.

Effect of the Invention

[0007] In the cornering characteristic evaluation method of the present disclosure, the correction angle δSA of the slip angle SA is calculated in the fourth step using the second speed V2 in the axial direction of the belt detected in the third step. Then, a corrected slip angle SA' is calculated in the fifth step using the correction angle δSA. Thereby, it becomes possible to suppress the influence of the movement of the belt in the axial direction in the evaluation of the cornering characteristics of the tire.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the present disclosure will be described based on the drawings. FIG. 1 is a perspective view showing a schematic configuration of a flat belt test apparatus 1 according to the present embodiment. FIG. 1 is a block diagram showing an electrical configuration of the flat belt test apparatus 1.

[0010] The flat belt test apparatus 1 is an apparatus for evaluating the cornering characteristics of a tire T. The flat belt test apparatus 1 includes a pair of rollers 2, an endless belt 3, a drive unit 4 for driving the rollers 2, a slip angle applying unit 54 for applying a slip angle SA to the tire T, a speed detection unit 6 for detecting the speed of the belt 3, and a calculation unit 7 for correcting the slip angle SA.

[0011] The pair of rollers 2 are arranged such that their axial directions are parallel to each other. In the present disclosure, unless otherwise specified, the "axial direction D1" is intended to be the axial direction of the roller 2.

[0012] The belt 3 is wound around a pair of rollers 2. The perimeter of the belt 3 is set in consideration of the diameter and the axial distance of the rollers 2 so that no slack occurs in the belt 3. The belt 3 is formed of, for example, stainless steel. The belt 3 has a running surface 31 on which the tire T runs. The running surface 31 is configured to be planar between the rollers 2.

[0013] The drive unit 4 rotationally drives the rollers 2. The drive unit 4 rotationally drives one of the rollers 2. The drive unit 4 may rotationally drive both of the rollers 2. When the rollers 2 rotate, the belt 3 circulates in an endless track shape.

[0014] For example, an electric motor is applied to the drive unit 4. By controlling the electric power supplied to the electric motor, the rotational speed of the roller 2 and thus the speed of the belt 3 in the direction perpendicular to the axial direction are adjusted. For example, the drive unit 4 rotationally drives the rollers 2 so that the belt 3 moves at a first speed V1 in the direction perpendicular to the axial direction. The drive unit 4 is controlled by, for example, a control unit (not shown). The control unit controls the entire flat belt test device 1.

[0015] The first speed V1 can be appropriately set as a measurement condition. Information regarding the set first speed V1 is input to a calculation unit 7 described later.

[0016] The tire T is supported by a support device 5 and runs on the belt 3. The support device 5 includes a rotating shaft 51 that rotates together with the tire T, a support portion 52 that cantilever supports the rotating shaft 51, a lifting portion 53 that raises and lowers the support portion 52, and a slip angle imparting portion 54 for imparting a slip angle SA to the tire T.

[0017] The tire T is mounted on a rim 55. A predetermined internal pressure is filled in the inner cavity of the tire T.

[0018] The rim 55 is coupled to the rotating shaft 51. The rotating shaft 51 is rotatably supported by the support portion 52.

[0019] The elevating part 53 moves the rotating shaft 51 in a direction perpendicular to the running surface 31. For example, when the elevating part 53 approaches the rotating shaft 51 to the running surface 31, the tire T is pressed against the running surface 31. The load borne by the tire T is adjusted by the elevating part 53. The elevating part 53 is controlled by, for example, the control part.

[0020] The slip angle imparting part 54 rotates the support part 52 around an axis perpendicular to the running surface 31. Thereby, a slip angle SA is imparted to the tire T running on the belt 3.

[0021] Note that the support device 5 may include a camber angle imparting part (not shown) that can adjust the angle of the support part 52 with respect to the running surface 31 so that the camber angle of the tire T with respect to the running surface 31 can be set.

[0022] As will be described later with reference to FIG. 3, the tire T to which the slip angle SA is imparted while running on the belt 3 generates a cornering force, and as a reaction, the belt 3 moves (displaces) in the axial direction D1. The amount of movement of the belt 3 is detected by the speed detection part 6.

[0023] The speed detection part 6 is arranged, for example, near the edge of the belt 3 in the axial direction D1. The speed detection part 6 detects the speed (second speed V2) of the belt 3 moving in the axial direction D1 by detecting the position of the edge of the belt 3. Information regarding the detected second speed V2 is input to the calculation part 7.

[0024] The calculation part 7 performs calculations for correcting the slip angle SA. For the calculation part 7, for example, a computer device having a CPU (Central Processing Unit), a program that controls the operation of the CPU, a memory that stores various information, etc. is applied. The calculation part 7 may be integrated with the above control part of the flat belt test device 1.

[0025] First, the calculation unit 7 calculates a correction angle δSA for correcting the slip angle SA from the first speed V1 and the second speed V2, and calculates a corrected actual slip angle SA' (see FIG. 3) using the correction angle δSA. By using the corrected slip angle SA' (see FIG. 3) calculated by the calculation unit 7, it becomes possible to correctly evaluate the cornering characteristics of the tire T.

[0026] FIG. 3 shows a tire T traveling on the belt 3 at the first speed V1. A slip angle SA is applied to the tire T. The slip angle SA is the angle of the equatorial plane of the tire T with respect to the traveling direction of the belt 3.

[0027] The tire T to which the slip angle SA is applied with respect to the traveling direction of the belt 3 generates a lateral force Fy. The component in the traveling direction of the belt 3 becomes the rolling resistance, and the component perpendicular to the traveling direction of the belt 3 becomes the cornering force CF.

[0028] At this time, the belt 3 receives a reaction force from the tire T. When the cornering force CF generated by the tire T increases and the force due to the above reaction exceeds the frictional force generated between the roller 2 and the belt 3, the belt 3 moves in the axial direction D1 of the roller 2. That is, the belt 3 moves (displaces) from the initial position shown by the broken line in FIG. 3 to the position shown by the solid line.

[0029] If the moving speed of the belt 3 in the axial direction D1 is the second speed V2, the traveling direction of the belt 3 becomes the sum of the first speed V1 and the second speed V2 synthesized as vectors with respect to the tire T. Then, the actual slip angle SA' of the tire T traveling on the belt 3 with displacement in the axial direction D1 becomes the angle of the equatorial plane of the tire T with respect to the traveling direction of the belt 3.

[0030] In evaluating the cornering characteristics of the tire T, accurate input of the slip angle SA as a parameter is important, and it is desirable to use the actual slip angle SA'. In the present disclosure, in order to correctly evaluate the cornering characteristics of the tire T, the apparent slip angle SA is corrected to the actual slip angle SA' from the first speed V1 and the second speed V2.

[0031] FIG. 4 is a flowchart showing the procedure of the cornering characteristic evaluation method 100 of the present disclosure. The cornering characteristic evaluation method 100 is a method for evaluating the cornering characteristics of the tire T using the flat belt test apparatus 1 including a pair of rollers 2 arranged in parallel as shown in FIG. 1 and an endless belt 3 wound around the pair of rollers 2.

[0032] The cornering characteristic evaluation method 100 includes a first step S1 of driving the belt 3 at the first speed V1, a second step S2 of applying a slip angle SA to the tire T, a third step S3 of detecting the second speed V2 of the belt 3, a fourth step S4 of calculating a correction angle δSA, and a fifth step S5 of calculating a corrected slip angle SA'.

[0033] In the first step S1, the driving unit 4 rotationally drives the roller 2, thereby driving the belt 3 in a direction perpendicular to the axial direction of the roller 2. The driving unit 4 rotationally drives the roller 2 so that the speed of the belt 3 becomes a predetermined first speed V1.

[0034] In the second step S2, the slip angle applying unit 54 rotates the support unit 52 about an axis perpendicular to the running surface 31. Thereby, an apparent slip angle SA is applied to the tire T running on the belt 3.

[0035] In the third step S3, accompanying the application of the slip angle SA in the second step S2, the second speed V2 of the belt 3 moving in the axial direction D1 of the roller 2 is detected. The second speed V2 is detected by the speed detection unit 6.

[0036] In the fourth step S4, a correction angle δSA for correcting the slip angle SA is calculated from the first speed V1 which is the speed of the belt 3 in the first step S1 and the second speed V2 detected in the third step S3. The correction angle δSA is calculated by the calculation unit 7.

[0037] In the fifth step S5, a corrected slip angle SA’ is calculated using the correction angle δSA calculated in the fourth step S4. The corrected slip angle SA’ is calculated by the calculation unit 7.

[0038] In the cornering characteristic evaluation method 100 of the present disclosure, the correction angle δSA of the slip angle SA is calculated in the fourth step S4 using the second speed V2 in the axial direction D1 of the belt 3 detected in the third step S3. Then, the corrected slip angle SA’ is calculated in the fifth step S5 using the correction angle δSA. Thereby, in the evaluation of the cornering characteristics of the tire T, it becomes possible to suppress the influence of the movement in the axial direction D1 of the belt 3.

[0039] When calculating the correction angle δSA in the fourth step S4, as shown in FIG. 3, a trigonometric function (tan) is used. That is, the correction angle δSA is calculated by the following equation (1). δSA = tan -1 (V1 / V2) (1) The correction angle δSA is easily calculated by equation (1).

[0040] In the fifth step S5, as shown by the following equation (2), the corrected slip angle SA’ is calculated by subtracting the correction angle δSA from the slip angle SA. SA’ = SA - δSA (2) The corrected slip angle SA’ is easily calculated by equation (2).

[0041] Figure 5 shows the transition of the position of the edge of the belt 3 detected by the speed detector 6. In this figure, with the position of the edge of the belt 3 at time 0 when a slip angle SA of 1.00 [deg] is applied in the second step S2 as the origin, the amount of movement of the belt 3 in the axial direction D1 is shown. The second speed V2 of the belt 3 is represented by the slope of the graph in Figure 5. The second speed V2 increases with the passage of time and becomes substantially constant after 25 seconds.

[0042] Figure 6 shows the relationship between the slip angle SA applied in the second step S2 and the corrected slip angle SA' calculated in the fifth step S5 in chronological order. The corrected slip angle SA' decreases with the amount of movement of the belt 3 in the axial direction D1 and becomes substantially constant at 0.99 [deg] after 25 seconds when the second speed V2 in Figure 5 becomes constant. That is, in the fourth step S4, a correction angle δSA of 0.01 [deg] is calculated, and in the fifth step S5, 0.99 [deg] is calculated as the corrected slip angle SA'.

[0043] By examining the relationship between the corrected slip angle SA' calculated by the flat belt test apparatus 1 and the cornering characteristic evaluation method 100 of the present disclosure and the lateral force Fy, the cornering characteristics of the tire T are correctly evaluated.

[0044] Figure 7 is a flowchart of a cornering characteristic evaluation method 101 which is a modified example of the cornering characteristic evaluation method 100 in Figure 4. Regarding the parts not described below in the cornering characteristic evaluation method 101, the configuration of the above-described cornering characteristic evaluation method 100 can be adopted.

[0045] The cornering characteristic evaluation method 101 includes the same first step S1 to fifth step S5 as the cornering characteristic evaluation method 100, a sixth step S6 for detecting the lateral force Fy generated by the tire T, and a seventh step S7 for calculating the time constant or relaxation length of the first-order lag system.

[0046] In the sixth step S6, instead of the lateral force Fy, the cornering force CF or the self-aligning moment Mz generated by the tire T may be detected.

[0047] FIG. 8 shows a block diagram of the transfer function of the first-order lag system calculated in the seventh step S7. In the seventh step S7, T is calculated by an optimization calculation so that the difference between the lateral force Fy calculated based on the block diagram of FIG. 8 and the lateral force Fy detected in the sixth step S6 becomes minimum, and is identified as the time constant τ. The same applies to the cornering force CF or the self-aligning moment Mz.

[0048] Then, the relaxation length σy is calculated by the following formula (3) as the product of the first speed V1 and the time constant τ. σy = τ × V1 (3)

[0049] In the seventh step S7, using the corrected slip angle SA' calculated in the fifth step S5 as an input value and using the lateral force Fy, the cornering force CF or the self-aligning moment Mz detected in the sixth step as an output value, the time constant τ or the relaxation length σy of the first-order lag system is calculated. The time constant τ or the relaxation length σy is calculated by the calculation unit 7.

[0050] According to the cornering characteristic evaluation method 101, since the time constant τ or the relaxation length σy of the first-order lag system is calculated using the corrected slip angle SA' calculated in the fifth step S5 as an input value, the time constant τ or the relaxation length σy can be accurately calculated, and the cornering characteristics of the tire T are correctly evaluated.

[0051] The cornering characteristic evaluation method 101 may include an eighth step (not shown) of calculating the time constant τ or the relaxation length σy of the second-order lag system after the seventh step S7.

[0052] Figure 9 shows a block diagram of the transfer function of the second-order lag system calculated in the eighth step. In the eighth step, ωn that minimizes the difference between the lateral force Fy calculated based on the block diagram of Figure 9 and the lateral force Fy detected in the sixth step S6 is calculated by an optimization calculation, and its reciprocal (1 / ωn) is identified as the time constant τ. The same applies to the cornering force CF or the self-aligning moment Mz. Also, the relaxation length σy is calculated by Equation (3).

[0053] In the eighth step, similar to the seventh step S7, the corrected slip angle SA' calculated in the fifth step S5 is used as the input value, and the lateral force Fy, cornering force CF, or self-aligning moment Mz detected in the sixth step is used as the output value to calculate the time constant τ or relaxation length σy of the second-order lag system. The time constant τ or relaxation length σy is calculated by the calculation unit 7.

[0054] According to such a cornering characteristic evaluation method 101, since the time constant τ or relaxation length σy of the second-order lag system is calculated using the corrected slip angle SA' calculated in the fifth step S5 as the input value, the time constant τ or relaxation length σy can be accurately calculated, and the cornering characteristics of the tire T can be correctly evaluated.

[0055] As described above, the flat belt test device 1 and the cornering characteristic evaluation method 100 of the present disclosure have been described in detail. However, the present disclosure is not limited to the above specific embodiments and can be implemented in various modes.

Example

[0056] A tire of size 235 / 55R18 assembled with a rim was filled with an internal pressure of 240 kPa and mounted on the flat belt test device 1. The above tire was loaded with a load of 6100 N, and when a slip angle of 1 [deg] was applied as a step input and gently accelerated from 0 to 1 km / h, the lateral force Fy was measured and the relaxation length was calculated. For the optimization calculation, MATLAB / Simulink (registered trademark) was used.

[0057] The relaxation length calculated by inputting the slip angle SA before correction was 397 mm, and the relaxation length calculated by inputting the slip angle SA' after correction was 424 mm.

[0058] It was confirmed that the relaxation length calculated by inputting the slip angle SA' after correction approaches the relaxation length obtained by drum tests, actual vehicle tests, simulations, etc. with respect to the relaxation length calculated by inputting the slip angle SA before correction.

[0059] [Appendix] The present disclosure includes the following aspects.

[0060] [Disclosure 1] A method for evaluating the cornering characteristics of a tire using a flat belt test device including a pair of rollers arranged in parallel and an endless belt wound around the pair of rollers, a first step of rotating the rollers to drive the belt in a direction perpendicular to the axial direction of the rollers at a predetermined first speed V1, a second step of applying a slip angle SA to the tire traveling on the belt, a third step of detecting a second speed V2 of the belt moving in the axial direction of the rollers as the slip angle SA is applied, a fourth step of calculating a correction angle δSA for correcting the slip angle SA from the first speed V1 and the second speed V2, and a fifth step of calculating a corrected slip angle SA' using the correction angle δSA, the cornering characteristic evaluation method. [Disclosure 2] The cornering characteristic evaluation method according to Disclosure 1, wherein in the fourth step, the correction angle δSA is calculated using a trigonometric function. [Disclosure 3] The cornering characteristic evaluation method according to Disclosure 1 or 2, wherein in the fifth step, the corrected slip angle SA' is calculated by subtracting the correction angle δSA from the slip angle SA. [Disclosure 4] A sixth step of detecting a lateral force, a cornering force, or a self-aligning moment generated by the tire; A seventh step of using the corrected slip angle SA' calculated in the fifth step as an input value and using the lateral force, the cornering force, or the self-aligning moment detected in the sixth step as an output value to calculate a time constant or a relaxation length of a first-order lag system, the cornering characteristic evaluation method according to any one of Disclosures 1 to 3. [Disclosure 5] An eighth step of using the corrected slip angle SA' calculated in the fifth step as an input value and using the lateral force, the cornering force, or the self-aligning moment detected in the sixth step as an output value to calculate a time constant or a relaxation length of a second-order lag system, the cornering characteristic evaluation method according to Disclosure 4. [Disclosure 6] A flat belt test device for evaluating the cornering characteristics of a tire, A pair of rollers arranged in parallel; An endless belt wound around the pair of rollers; A drive unit that rotationally drives the rollers so that the belt moves at a first speed V1 in a direction perpendicular to the axial direction of the rollers; A slip angle applying unit that applies a slip angle SA to the tire traveling on the belt; A speed detection unit that detects a second speed V2 of the belt moving in the axial direction of the rollers as the slip angle SA is applied; A flat belt test device including a calculation unit that calculates a correction angle δSA for correcting the slip angle SA from the first speed V1 and the second speed V2 and calculates a corrected slip angle SA' using the correction angle δSA.

Explanation of Signs

[0061] 1 Flat belt test device 2 Roller 3 Belt 4 Drive unit 6 Speed detection unit 7 Calculation unit 54 Slip angle application unit 100 Cornering characteristic evaluation method 101 Cornering characteristic evaluation method CF Cornering force D1 Axial direction Fy Lateral force Mz Self-aligning moment S1 First step S2 Second step S3 Third step S4 Fourth step S5 Fifth step S6 Sixth step S7 Seventh step SA Slip angle SA’ Slip angle T Tire V1 First speed V2 Second speed δSA Correction angle σy Relaxation length τ Time constant

Claims

1. A method for evaluating the cornering characteristics of a tire using a flat belt test device including a pair of rollers arranged in parallel and an endless belt wound around the pair of rollers, a first step of rotating the rollers and driving the belt in a direction perpendicular to the axial direction of the rollers at a predetermined first speed V1, a second step of applying a slip angle SA to the tire traveling on the belt, a third step of detecting a second speed V2 of the belt moving in the axial direction of the rollers as the slip angle SA is applied, a fourth step of calculating a correction angle δSA for correcting the slip angle SA from the first speed V1 and the second speed V2, and a fifth step of calculating a corrected slip angle SA' using the correction angle δSA. A cornering characteristic evaluation method comprising:

2. The cornering characteristic evaluation method according to claim 1, wherein in the fourth step, the correction angle δSA is calculated using a trigonometric function.

3. The cornering characteristic evaluation method according to claim 1 or 2, wherein in the fifth step, the corrected slip angle SA' is calculated by subtracting the correction angle δSA from the slip angle SA.

4. a sixth step of detecting a lateral force, a cornering force, or a self-aligning moment generated by the tire, and a seventh step of calculating a time constant or a relaxation length of a first-order lag system using the corrected slip angle SA' calculated in the fifth step as an input value and the lateral force, the cornering force, or the self-aligning moment detected in the sixth step as an output value. The cornering characteristic evaluation method according to any one of claims 1 to 3.

5. An eighth step of calculating a time constant or a relaxation length of a second-order lag system using the corrected slip angle SA' calculated in the fifth step as an input value and the lateral force, the cornering force, or the self-aligning moment detected in the sixth step as an output value. The cornering characteristic evaluation method according to claim 4.

6. A flat belt test device for evaluating the cornering characteristics of a tire, a pair of rollers arranged in parallel, and an endless belt wound around the pair of rollers, A drive unit that rotationally drives the roller so that the belt moves at a first speed V1 in a direction perpendicular to the axial direction of the roller; A slip angle imparting unit that imparts a slip angle SA to the tire traveling on the belt; A speed detection unit that detects a second speed V2 of the belt that moves in the axial direction of the roller as the slip angle SA is imparted; A flat belt test apparatus including a calculation unit that calculates a correction angle δSA for correcting the slip angle SA from the first speed V1 and the second speed V2, and calculates a corrected slip angle SA' using the correction angle δSA.

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