JP7151292B2 - Evaluation method of tire performance - Google Patents

Description

The present invention relates to a method for evaluating tire performance.

A running test machine with a running surface is used to evaluate tire performance. In this test, the tire is pressed with a given load against a running surface moving at a given speed. As a result, tire performance such as friction coefficient and braking distance is measured by running the tire on a running surface.

Tire performance is dependent on temperature. For example, the dynamic friction coefficient of a tire on ice decreases as the ice surface temperature approaches 0°C from minus. If the ice surface temperature differs by 1.0°C, the coefficient of dynamic friction changes by about 8%. The environmental temperature of the running test machine is adjusted to a predetermined value in order to suppress the influence of temperature and evaluate tire performance with high accuracy. A method for testing tires while adjusting the environmental temperature is disclosed in Japanese Patent Application Laid-Open No. 2015-17861.

Japanese Patent Application Laid-Open No. 2015-17861

The temperature of the running surface does not necessarily match the environmental temperature of the running test machine. Even if the environmental temperature is the same, the temperature of the running surface may vary depending on the day and time of the evaluation. In order to more accurately measure the performance of tires, there is a demand for a test method that can accurately adjust the temperature of the running surface to a predetermined temperature.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tire testing method capable of accurately adjusting the temperature of the running surface.

The tire performance evaluation method according to the present invention includes:
A step of setting the tire on a running test machine having a running surface, measuring the temperature of the running surface, and adjusting the environmental temperature of the running test machine so that the running surface reaches a predetermined temperature based on the temperature measurement result. and measuring performance of the tire by running the tire on the running surface.

Preferably, said running surface is an ice surface.

Preferably, the measured tire performance is the coefficient of friction of the tire.

Preferably, the environmental temperature of the running test machine is adjusted by a temperature controller having a blower function, and the direction of the wind and the position of the running surface are controlled so that the air from the temperature controller does not directly hit the running surface. relationship is adjusted.

Preferably, the running test machine is installed in a test room, and the front direction of the door of the test room is perpendicular to the blowing direction of the temperature controller.

The tire performance evaluation equipment according to the present invention includes a running test machine that has a running surface on which the tire runs and a temperature measuring device that measures the temperature of the running surface, and is capable of measuring the performance of the tire. A temperature controller capable of adjusting the environmental temperature, and a controller for controlling the temperature controller so that the temperature of the running surface becomes a predetermined temperature based on the measurement result of the temperature of the running surface are provided.

In the tire performance evaluation method according to the present invention, the temperature of the running surface is measured, and the environmental temperature of the running test machine is adjusted based on the temperature measurement result so that the running surface reaches a predetermined temperature. While performing this temperature adjustment, tire performance is measured. In this method, the performance of the tire is measured while the temperature of the running surface is accurately adjusted to a predetermined value. This contributes to improving the accuracy of tire performance measurement. With this method, tire performance can be evaluated with high accuracy.

FIG. 1 is a schematic diagram showing evaluation equipment used in a tire performance evaluation method according to an embodiment of the present invention. 2 is a front view conceptually showing a running test machine used in the facility of FIG. 1. FIG. FIG. 3 is a graph showing changes in environmental temperature during performance measurement for the present method and the conventional method. FIG. 4 is a graph showing changes in the temperature of the running surface during performance measurement for this method and the conventional method. FIG. 5 is a graph showing the relationship between the running surface temperature and the dynamic friction coefficient in this method.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

FIG. 1 is a schematic diagram showing evaluation equipment 2 used in a tire evaluation method according to an embodiment of the present invention. This equipment 2 is provided in a test chamber 4 . As shown in FIG. 1, the facility 2 includes a running test machine 6, a temperature controller 8 and a controller 10. FIG. 2 is a front view conceptually showing the running test machine 6 of FIG.

The running test machine 6 measures tire performance. The running test machine 6 includes a drum 12 , a tire support section 14 , a drum support section 16 , a temperature measuring device 18 and a base section 20 . FIG. 2 also shows a tire 22 to be evaluated. Of these, only the drum 12, the tire 22 and the temperature measuring device 18 are shown in the running test machine 6 of FIG.

The drum 12 has a cylindrical shape. In FIG. 2 the drum 12 is shown in cross section. One axial surface of the drum 12 has an opening 24 (this surface is referred to as the opening surface 26) and the other surface of the drum 12 has no openings (this surface is the bottom surface). 28). As shown in FIG. 2, when testing the tire 22, the tire 22 is inserted into the drum 12 from the opening surface 26 side. An ice layer 30 having a constant thickness is formed on the inner peripheral surface of the drum 12 . The surface of the ice layer 30 (ice surface 32) is smoothed and polished. This ice surface 32 constitutes a running surface 34 on which the tire 22 runs. In this embodiment, the running test machine 6 is for measuring the on-ice performance of the tire 22 . This running test machine 6 is of the inside drum type.

The tire support portion 14 is positioned outside the opening surface 26 of the drum 12 . The tire support section 14 has a rotating shaft 36 , a tire driving section 38 , an elevator 40 and a load cell 42 . A tire 22 is mounted on the rotating shaft 36 . The tire driving section 38 controls the rotation of the rotating shaft 36 and the deceleration and stopping of this rotation. The tire driver 38 allows the tire 22 to be controlled to rotate, decelerate, and stop. The elevator 40 moves the rotary shaft 36 in the vertical direction (vertical direction in FIG. 2). Tire 22 may be moved vertically by elevator 40 . A load cell 42 measures the force applied to the tire 22 . The load cell 42 measures the reaction force (load) Fz applied from the drum 12 to the tire 22 in the radial direction and the reaction force (longitudinal force) Fx applied in the circumferential direction.

The tire support portion 14 is horizontally movable on the base portion 20 . Thereby, the tire 22 can be moved horizontally (horizontal direction in FIG. 2) with respect to the drum 12 . This horizontal movement, along with the vertical movement provided by the elevator 40 previously described, allows the tire 22 to contact the running surface 34 of the drum 12 at a desired location. A desired load can be applied to the tire 22 by this vertical movement. Furthermore, the tire support portion 14 can tilt the direction in which the rotating shaft 36 extends with respect to the axial direction of the drum 12 . Thereby, a desired camber angle and slip angle can be given to the tire 22 .

The drum support 16 is located outside the bottom surface 28 of the drum 12 . The drum support section 16 includes a drum rotating shaft 44 , a bearing 46 and a drum driving section 48 . The drum rotation shaft 44 connects with the bottom surface 28 of the drum 12 . A bearing 46 supports the drum rotating shaft 44 . The drum drive unit 48 can rotate the drum 12 at a desired speed by rotating the drum rotating shaft 44 .

A temperature measuring device 18 is located inside the drum 12 . A temperature measuring device 18 measures the temperature of the running surface 34 . In this embodiment, temperature measuring device 18 measures the temperature of ice surface 32 . Measurement results are sent to the controller 10 . Typically the temperature measuring device 18 is an infrared thermograph. The temperature of the ice surface 32 may be measured with a contact thermometer.

A temperature controller 8 adjusts the temperature in the test chamber 4 . In this embodiment, the temperature adjuster 8 is an air conditioner that adjusts the air temperature in the test chamber 4 by blowing hot air or cold air. This temperature controller 8 has a cooling and heating function. The temperature adjuster 8 can adjust the environmental temperature of the running test machine 6 .

The temperature of the running surface 34 measured by the temperature measuring device 18 is sent to the controller 10 . Controller 10 can control temperature controller 8 . The controller 10 can change the cooling intensity or heating intensity of the temperature controller 8 . A line connecting the controller 10 and the temperature measuring device 18 is drawn in FIG. is. There does not necessarily have to be a physical wire between them. For example, the measurement results may be sent wirelessly. Similarly, between the controller 10 and the temperature controller 8, physical wiring may or may not exist between them.

A method for evaluating the performance of a tire 22 according to the invention uses the evaluation facility 2 shown in FIGS. This evaluation method is
(1) a step of setting the tire 22 on the running test machine 6; and (2) a step of measuring the performance of the tire 22.

In step (1) above, the inside of the tire 22 to be evaluated is filled with air so that it has a predetermined internal pressure. This tire 22 is mounted on the rotating shaft 36 of the tire support portion 14 .

In step (2) above, the performance of the tire 22 is measured. In this embodiment, a dynamic friction coefficient measurement is made. In this measurement the drum 12 is rotated at a predetermined rotational speed. The tire 22 is non-rotatably restrained. In this state, the tire 22 is pressed against the running surface 34 of the drum 12 with a predetermined load Fz. Tire 22 slides on ice surface 32 . The rotational speed of the drum 12 is the ice sliding speed of the tire 22 . At this time, the load cell 42 measures the longitudinal force Fx applied to the tire 22 . A dynamic friction coefficient μ of the tire 22 is obtained by the following formula.
μ = Fx/Fz
Thereby, the dynamic friction coefficient μ at the desired rotation speed is measured.

In step (2) above, the dynamic friction coefficient is measured and the temperature of the running surface 34 is adjusted. The controller 10 controls the temperature adjuster 8 from the temperature of the running surface 34 measured by the temperature measuring device 18 . When the temperature of the running surface 34 is higher than a predetermined temperature, the controller 10 increases the cooling capacity of the temperature controller 8 to lower the environmental temperature. This reduces the temperature of the running surface 34 . When the temperature of the running surface 34 is lower than the predetermined temperature, the controller 10 increases the heating capacity of the temperature controller 8 to increase the ambient temperature. This raises the temperature of the running surface 34 . As a result, the running surface 34 is adjusted to a desired temperature.

The effects of the present invention will be described below.

In the method for evaluating the performance of the tire 22 according to the present invention, the temperature of the running surface 34 is measured, and based on the temperature measurement result, the environmental temperature of the running test machine 6 is adjusted so that the running surface 34 reaches a predetermined temperature. be. While performing this temperature adjustment, the performance of the tire 22 is measured. In this method, the performance of the tire 22 is measured while the temperature of the running surface 34 is accurately adjusted to a predetermined value. This contributes to improving the accuracy of performance measurement of the tire 22 . With this method, the performance of the tire 22 can be evaluated with high accuracy.

In FIG. 1 , arrow A represents the direction of the wind sent from temperature controller 8 . In this embodiment, the wind direction A is directed toward the outer peripheral surface of the drum 12 . This wind does not hit the running surface 34 directly. In this way, it is preferable that the relationship between the direction of the wind and the position of the running surface 34 is adjusted so that the wind from the blower does not hit the running surface 34 directly. Thereby, the temperature of the running surface 34 can be adjusted with high accuracy. With this method, the performance of the tire 22 can be evaluated with high accuracy.

In FIG. 1, the front direction of the door 50 of the entrance/exit of the test room 4 is different from the direction A of the air from the temperature controller 8. In FIG. The wind direction A and the front direction of the door 50 are perpendicular. Here, the front direction of the door 50 means a direction perpendicular to the front surface of the door 50 when the door 50 is closed. By doing so, the influence of the opening and closing of the door 50 on the environmental temperature can be reduced. Further, by positioning the drum 12 away from the door 50, the opening and closing of the door 50 has less effect on the temperature of the running surface 34. With these, the temperature of the running surface 34 can be adjusted with high accuracy. With this method, the performance of the tire 22 can be evaluated with high accuracy.

In the above embodiment, the dynamic friction coefficient on ice was measured as the performance of the tire 22 . As the performance of the tire 22, the dynamic friction coefficient on the dry running surface 34 and the wet running surface 34 may be measured. Other characteristics such as braking distance and wear may also be measured as tire 22 performance.

In the embodiment described above, the running test machine 6 was of the inside drum type. The running test machine may be of the outside drum type. The running test machine may be of a flat belt type.

The effects of the present invention will be clarified by examples below, but the present invention should not be construed in a limited manner based on the description of these examples.

[Example 1]
Using the equipment shown in FIG. 1, the dynamic friction coefficient of the tire was measured by the method according to the present invention. In this evaluation, the temperature of the running surface was adjusted to -1.1°C.

[Comparative Example 1]
The ambient temperature was measured during the evaluation and adjusted to -1.1°C. The dynamic friction coefficient of the tire was measured in the same manner as in Example 1 except for this.

[Temperature variation]
For each of Example 1 and Comparative Example 1, changes in environmental temperature and changes in running surface temperature (ice surface temperature) were measured during the measurement of the dynamic friction coefficient. FIG. 3 shows changes in environmental temperature, and FIG. 4 shows changes in ice surface temperature. 3 and 4, Example 1 is indicated by symbol a, and Comparative Example 1 is indicated by symbol b. In Example 1, the variation in environmental temperature is greater than that in Comparative Example 1, but the variation in ice surface temperature is smaller. The ratio (σE/σC) between the standard deviation σE of the ice surface temperature of Example 1 and the standard deviation σC of the ice surface temperature of Comparative Example 1 was 27%. The difference between the maximum and minimum ice surface temperatures was 0.2°C in Example 1 and 1.6°C in Comparative Example 1.

[Variation in coefficient of dynamic friction]
For each of Example 1 and Comparative Example 1, the dynamic friction coefficient μ was measured 20 times under the same temperature setting as the evaluation of temperature variation. The ratio of the difference between the maximum value and the minimum value of the dynamic friction coefficient μ to the average of the dynamic friction coefficient μ was calculated as the maximum error rate. The maximum error rate of Example 1 was 1.6%, and the maximum error rate of Comparative Example 1 was 8.0%.

[Temperature dependence of dynamic friction coefficient]
The dynamic friction coefficient μ was measured by the method of Example 1. Eight measurements were carried out at ice surface temperatures between -1°C and -2°C. The results are shown in FIG. When performing regression analysis of the relationship between the ice surface temperature and the coefficient of dynamic friction μ, the regression formula was y=−0.0182x+0.1524, and the coefficient of determination ^R2 was 0.9208. These indicate that the ice surface temperature and the dynamic friction coefficient μ have a high correlation. This indirectly indicates that the evaluation accuracy is high.

As described above, the evaluation methods of Examples are comprehensively superior to the evaluation methods of Comparative Examples. From this evaluation result, the superiority of the present invention is clear.

The methods described above can also be applied to evaluate different performances of different tires.

2 Evaluation facility 4 Testing room 6 Running test machine 8 Temperature controller 10 Controller 12 Drum 14 Tire support 16 Drum support Part 18...Temperature measuring device 20...Base part 22...Tire 24...Opening 26...Opening surface 28...Bottom surface 30...Ice layer 32...Ice surface 34... - Running surface 36... Rotary shaft 38... Tire drive part 40... Elevator 42... Load cell 44... Drum rotary shaft 46... Bearing 48... Drum drive part 50... Door

Claims (5)

A step of setting the tire on a running test machine having a running surface, measuring the temperature of the running surface, and adjusting the environmental temperature of the running test machine so that the running surface reaches a predetermined temperature based on the temperature measurement result. , including the step of running the tire on the running surface and measuring the performance of the tire;
The environmental temperature of the running test machine is adjusted by a temperature controller having a blower function, and the relationship between the direction of the wind and the position of the running surface so that the air from the temperature controller does not hit the running surface directly. A method of evaluating tire performance, adjusted for The evaluation method according to claim 1, wherein the running surface is an ice surface. 3. The evaluation method according to claim 1, wherein the measured tire performance is a tire friction coefficient. 4. The evaluation method according to any one of claims 1 to 3, wherein the running test machine is installed in a test room, and the front direction of the door of the test room is perpendicular to the blowing direction of the temperature controller. A running tester that has a running surface on which the tire runs and a temperature measuring device that measures the temperature of the running surface and is capable of measuring the performance of the tire,
A temperature controller that can adjust the environmental temperature of the running test machine,
and a controller for controlling the temperature controller so that the temperature of the running surface becomes a predetermined temperature based on the measurement result of the temperature of the running surface ,
The environmental temperature of the running test machine is adjusted by a temperature controller having a blower function, and the relationship between the direction of the wind and the position of the running surface so that the air from the temperature controller does not hit the running surface directly. A tire performance evaluation facility that is adjusted to

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