Method for evaluating tire noise performance

Abstract

This invention provides a method for evaluating tire noise performance that allows for a simple assessment of tire noise performance during acceleration. [Solution] This is a method for evaluating the noise performance of a tire. It includes a first step S1 of accelerating the tire on a simulated road surface, a second step S2 of measuring the amount of circumferential slip of the tire at an arbitrary contact point of the tire that is in contact with the simulated road surface during acceleration, and an evaluation step S3 after the second step S2, which evaluates the noise performance of the tire during acceleration based on the amount of slip.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the noise performance of tires.

Background Art

[0002] In Non-Patent Document 1 below, a slick tire method using slick tires is described as a method for measuring and evaluating tire noise during acceleration. With this slick tire method, it is possible to evaluate the tire noise during acceleration from which the noise caused by the vehicle (engine) has been removed.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described slick tire method, it is necessary to measure the noise when the vehicle equipped with the test tire is accelerating, the noise when the vehicle equipped with the slick tire is accelerating, and the noise when the vehicle equipped with the slick tire is coasting, respectively, and there is a problem that it requires a lot of labor.

[0005] The present invention has been devised in view of the above problems, and the main object is to provide a method for evaluating the noise performance of tires that can easily evaluate the noise performance of tires during acceleration.

Means for Solving the Problems

[0006] The present invention relates to a method for evaluating the noise performance of a tire, comprising: a first step of accelerating the tire on a simulated road surface; a second step of measuring the amount of circumferential slip of the tire at any point of contact with the simulated road surface during the accelerating run; and an evaluation step of evaluating the noise performance of the tire during accelerating run based on the amount of slip after the second step. [Effects of the Invention]

[0007] The present invention provides a method for evaluating the noise performance of tires, which, by employing the above configuration, allows for easy evaluation of the noise performance of tires during acceleration. [Brief explanation of the drawing]

[0008] [Figure 1] This is a flowchart showing the method for evaluating the noise performance of a tire according to the present invention. [Figure 2] This is a side view conceptually illustrating the evaluation apparatus of the first embodiment. [Figure 3] Figure 2 is a front view. [Figure 4] This is a schematic diagram showing the contact surface as captured by the camera in the second step. [Figure 5] This graph shows the change in the amount of slip from ground entry to ground exit at a single contact point. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. The drawings may contain exaggerations or representations that differ from the actual dimensional ratios of the structure in order to aid in understanding the content of the present invention. Furthermore, the same or common elements are denoted by the same reference numerals throughout each embodiment, and redundant explanations may be omitted. In addition, the specific configurations shown in the embodiments and drawings are for the purpose of understanding the content of the present invention. It should be noted that the present invention is not limited to the specific configurations shown in the drawings.

[0010] Figure 1 is a flowchart of the noise performance evaluation method (hereinafter sometimes simply referred to as the "evaluation method") of the present invention. In the present invention, the noise performance of a tire (shown in Figure 2) T is evaluated. The tire T to be evaluated in the present invention includes various types of tires, including pneumatic tires for passenger cars, motorcycles, and heavy loads, as well as airless tires that are not filled with compressed air.

[0011] Furthermore, if the tire T used in the evaluation method is a pneumatic tire, it is desirable that it be mounted on a standard rim (not shown) and filled to the standard pressure (hereinafter sometimes referred to as the "reference state"). The "standard rim" is the rim specified for each tire in the standard system that includes the standard on which the tire is based. For example, it is the "standard rim" for JATMA, the "Design Rim" for TRA, and the "Measuring Rim" for ETRTO. The "standard pressure" is the air pressure specified for each tire in the standard system that includes the standard on which the tire is based. For example, it is the "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and the "INFLATION PRESSURE" for ETRTO. Note that if the tire is for a passenger car, the standard pressure is 180kPa.

[0012] As shown in Figure 1, the evaluation method of this embodiment includes a first step S1, a second step S2, and an evaluation step S3. In the first step S1, the tire T is accelerated on a simulated road surface (shown in Figure 2) 2. In the second step S2, during the acceleration run in the first step S1, the amount of slip S in the circumferential direction of the tire (hereinafter sometimes simply referred to as "slip amount S") at an arbitrary contact point K of the tire T that is in contact with the simulated road surface 2 is measured (shown in Figure 4). In the evaluation step S3, after the second step S2, the noise performance of the tire T during acceleration run is evaluated based on the slip amount S.

[0013] Various studies have revealed that tire noise during acceleration is caused by vibrations transmitted to the surrounding air due to the circumferential slip of the tire tread (shown in Figure 2) Tt relative to the road surface. It has also been found that there is a correlation between the amount of slip S during acceleration and the magnitude of the noise. Based on these findings, the noise performance evaluation method of the present invention includes a second step S2 and an evaluation step S3. As a result, the noise performance evaluation method of this embodiment allows for the evaluation of noise performance without directly measuring the noise of the tire T during acceleration. In other words, the evaluation method of this embodiment allows for a simpler evaluation of noise performance during acceleration compared to, for example, measuring noise by mounting four test tires on a vehicle or measuring noise using the slick tire method described in Non-Patent Literature 1. It has also been found that there is no correlation between the amount of slip S and the magnitude of the noise during constant speed driving (zero acceleration).

[0014] Next, an embodiment of the evaluation device 1 used in the evaluation method will be described. Figure 2 is a conceptual side view of the evaluation device 1 of this embodiment, and Figure 3 is a front view of Figure 2. As shown in Figures 2 and 3, the evaluation device 1 includes a simulated road surface 2 on which the tire T runs. The evaluation device 1 also includes, for example, a frame 3, a running platform 4, a tire support 5, and a measuring instrument 6.

[0015] The simulated road surface 2 is in contact with the contact surface Ta of the tire T during travel. The simulated road surface 2 is formed in a rectangular shape, for example, with a long length in the tire direction of travel F. In this embodiment, the simulated road surface 2 includes a transparent plate 2s, for example, glass or acrylic resin. The simulated road surface 2 is formed entirely of a transparent plate 2s. The upper surface of the simulated road surface 2 is formed as a flat surface. The tire direction of travel F is the longitudinal direction of the simulated road surface 2.

[0016] The frame 3 is provided with, for example, legs 3a extending vertically from the floor surface, a support portion 3b extending horizontally at the upper ends of the legs 3a, and a pair of slide rails 3c, 3c disposed on the upper surface of the support portion 3b. In this embodiment, the support portion 3b supports the pseudo road surface 2 so as to be horizontal. The pair of slide rails 3c, 3c extends, for example, along the tire traveling direction F. Also, each of the pair of slide rails 3c, 3c is located on both sides in the width direction of the pseudo road surface 2.

[0017] Further, the support portion 3b is provided with a hole portion (not shown) that exposes the pseudo road surface 2 downward (back side). Thereby, the contact surface Ta of the tire T can be seen through from the lower side of the pseudo road surface 2 through the hole portion (not shown) of the support portion 3b. The hole portion of this embodiment is ensured to have a size that can see through the ground entry c1 and the ground exit c2 (shown in FIG. 4) at the contact point K of the tire T.

[0018] The running base 4 includes, for example, an upper frame portion 4a and legs 4b. The upper frame portion 4a is formed in a rectangular shape in plan view and is arranged horizontally. The legs 4b extend downward from the four corners of the upper frame portion 4a. Linear guides 4c that engage with the slide rails 3c, 3c are provided at the lower ends of each leg 4b. Thereby, the running base 4 can be horizontally moved in the tire traveling direction F on the pair of slide rails 3c, 3c. Also, the running base 4 of this embodiment is controllably moved at a predetermined acceleration by a first driving tool (not shown) provided on the frame 3. As the first driving tool, it is desirable to use a well-known ball screw mechanism including a ball screw shaft extending parallel to the slide rail 3c, a drive motor for driving the ball screw shaft, and a nut portion attached to the running base 4 and rotatably held on the ball screw shaft.

[0019] The tire support 5 is configured to include, for example, a base 5a, a lift table 5b, a vertical shaft 5c, and a tire support shaft 5d. The base 5a is fixed above the upper frame portion 4a of the traveling base 4. The lift table 5b is supported so as to be able to move up and down via a first lifting device (not shown) provided on the base 5a. The upper end side of the vertical shaft 5c is fixed to the lift table 5b. The tire support shaft 5d includes a first portion 9a extending horizontally from the lower end side of the vertical shaft 5c, a second portion 9b extending downward from one end of the first portion 9a, and a third portion 9c extending horizontally from the lower end of the second portion 9b. Thus, in this embodiment, the tire support shaft 5d is formed in a substantially U shape when viewed from the front. At one end of the third portion 9c, the tire T is rotatably supported around the tire rotation axis Tc via the rim R.

[0020] With such a tire support 5, the tire T supported by the tire support shaft 5d can be moved up and down via the lift table 5b. Thereby, the tire T can be grounded on the simulated road surface 2 and a load can be applied to the tire T. The tire support 5 supported by the traveling base 4 can be horizontally moved in the tire traveling direction F by the first driving device (not shown) provided on the frame 3. Thereby, the tire T to which the load is applied can be accelerated on the simulated road surface 2.

[0021] The measuring device 6 of this embodiment is configured as a camera 6s. The camera 6s is set below the simulated road surface 2. With such a camera 6s, the contact surface Ta of the tread portion Tt of the tire T grounded on the simulated road surface 2 can be photographed. Also, the video photographed by the camera 6s is subjected to image processing by, for example, a computer (not shown) or the like. Thereby, the slip amount S (shown in FIG. 4) of the contact point K of the tire T traveling on the simulated road surface 2 is measured. Also, it is desirable that the camera 6s of this embodiment is a video camera capable of continuously photographing the contact surface Ta of the tire T traveling on the simulated road surface 2.

[0022] Next, an evaluation method using the evaluation device 1 of this embodiment will be described. In the first step S1 of this embodiment, first, the tire T is rotatably supported on one end of the third portion 9c of the tire support shaft 5d. Then, the tire T is brought into contact with the simulated road surface 2 under a normal load condition by the first lifting device. Next, the running platform 4 is moved by the first drive device provided on the frame 3, and the tire T supported on the tire support shaft 5d travels on the simulated road surface 2 at a predetermined acceleration. The acceleration in the first step S1 is not particularly limited, but is 0.05 m / s². 2 The above is desirable, 0.08 m / s 2 The above is even more desirable, 0.2 m / s 2 The following is preferable, 0.17 m / s 2 The following is even more desirable: It has been found that within this acceleration range, it is possible to represent (reproduce) the noise results during acceleration driving in normal road conditions.

[0023] The "normal load condition" refers to the state when the tire T in the standard condition is subjected to a normal load and made contact with a flat surface at a camber angle of 0 degrees. The "normal load" is the load specified for each tire by the aforementioned standard; for JATMA, it is the maximum load capacity; for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and for ETRTO, it is "LOAD CAPACITY". The driving conditions of the tire T are not limited to these forms. For example, the tire T may have a camber angle or slip angle applied to the simulated road surface 2.

[0024] Next, the second step S2 using the evaluation device 1 of this embodiment will be described. In the second step S2, the contact point K (shown in Figure 4) is photographed by a camera 6s positioned below the simulated road surface 2 formed by a transparent plate 2s. The amount of slip S at the contact point K is then measured by image processing of the captured image. The contact point K is any one point on the contact surface Ta. In this specification, the contact surface Ta is the surface that contacts the flat surface under the normal load condition. Furthermore, a more specific method for measuring the amount of slip S is described in Japanese Patent Application Publication No. 2013-019756 and Japanese Patent Application Publication No. 2010-078416.

[0025] Figure 4 is a schematic diagram showing the contact surface Ta as captured by camera 6s in the second step S2. Figure 4 shows the contact surface Ta as captured through a transparent plate 2s. As shown in Figure 4, in the second step S2, for example, the amount of slip S at multiple contact points Kn (where n is a natural number greater than or equal to 1) may be measured. By measuring the amount of slip S at multiple contact points Kn, the accuracy of the noise performance is improved. In particular, when the amount of slip S at multiple contact points Kn is measured, it is desirable that the amount of slip S be calculated as the average value of the amount of slip S at all contact points Kn. Furthermore, the multiple contact points Kn may be located, for example, in the crown region Cr of the contact surface Ta and in the shoulder region Sh located on both sides of the crown region Cr in the tire axial direction. Even when such contact points Kn are selected, the accuracy of the noise performance is improved. Furthermore, the multiple contact points Kn may be, for example, one point per 1 square cm of the contact surface Ta, or one point per 10 square cm of the contact surface Ta.

[0026] Figure 5 is a graph showing the change in the amount of slip S from contact point c1 to contact point c2 at a single contact point K. The vertical axis of Figure 5 represents the amount of slip S (length in the circumferential direction of the tire) in units of mm. If the amount of slip S is greater than 0 mm, it indicates that slip is occurring in the opposite direction to the tire rotation direction, and if the amount of slip S is less than 0 mm, it indicates that slip is occurring in the direction of tire rotation. The horizontal axis of Figure 5 represents the elapsed time from contact point c1 in units of seconds (sec). The longer the elapsed time, the closer the contact point K is to contact point c2.

[0027] As shown in Figure 5, the maximum absolute value Sm of the slip amount S is located on the contact exit c2 side rather than the contact entry c1 side. Also, the slip amount S is 0 mm (strictly speaking, slip occurs, but it can be said to be 0 mm) for 65% to 85% of the total time from contact entry c1 to contact exit c2. From this viewpoint, in the second step S2, it is desirable to measure the slip amount S from the contact center c3 to the contact exit c2, and it is desirable to measure the maximum value Sm of the slip amount S from the contact center c3 to the contact exit c2. This allows for a more accurate evaluation of noise performance. The contact center c3 is the midpoint in the circumferential direction of the tire's circumferential movement length La (shown in Figure 4) from contact entry c1 to contact exit c2 on the simulated road surface 2.

[0028] Next, evaluation step S3 using the evaluation device 1 will be described. In this evaluation step S3, the noise performance of the tire T during acceleration is evaluated based on the amount of slip S. Various studies have shown that there is a positive correlation between the amount of slip S and the magnitude of the noise. Therefore, in evaluation step S3, the smaller the amount of slip S, the better the noise performance is judged to be. Thus, with the noise performance evaluation method using the evaluation device 1 of this embodiment, the noise performance during acceleration can be easily evaluated without directly measuring the noise of the tire T during acceleration.

[0029] The evaluation device 1 can be placed, for example, in a room (not shown). In the first step S1, for example, a tire T whose temperature is controlled at room temperature is used. For example, a tire T that has been stored in a room for 8 to 24 hours is used. This ensures that even when evaluating multiple types of tires T, the temperature of these tires T is the same, allowing for accurate evaluation of noise performance.

[0030] In order to effectively exert the effects described above, it is desirable that the room temperature be controlled to a predetermined temperature. It is desirable that the room temperature be controlled by, for example, a well-known air conditioner (not shown in the illustration).

[0031] Furthermore, various experiments have revealed that the noise performance of tire T also changes with the temperature of tire T. For this reason, in the first step S1, tire T that has been heated to a temperature higher than room temperature by a temperature control device (not shown), or tire T that has been heated to a temperature lower than room temperature by a temperature control device, may be used. Desirable temperature control devices include, for example, a tire warmer with a heater for heating tire T, and a refrigerator with a compressor for cooling tire T. For tire warmers, for example, one with a heater temperature of 30 to 80°C is desirable. For refrigerators, for example, one with an internal temperature of -10 to 10°C is desirable. Well-known tire warmers and refrigerators can be used. Thus, since the evaluation device 1 can be used indoors, the noise performance evaluation method of the present invention can also be used for tire T at high temperatures and tire T at low temperatures.

[0032] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above and can be implemented in various modified forms.

[0033] [Note] The present invention includes the following embodiments.

[0034] [Invention 1] A method for evaluating the noise performance of tires, The first step involves accelerating the tires on a simulated road surface, During the aforementioned acceleration run, a second step is to measure the amount of circumferential slip of the tire at any point of contact with the simulated road surface of the tire, The process includes, after the second step, an evaluation step of evaluating the noise performance of the tire during acceleration based on the amount of slip, Methods for evaluating tire noise performance. [Invention 2] The aforementioned simulated road surface includes a transparent plate, The method for evaluating the noise performance of a tire according to the present invention 1, wherein in the second step, the amount of slip is measured by photographing the contact point through the transparent plate. [Invention 3] In the evaluation step, the smaller the amount of slip, the better the noise performance is evaluated, in the method for evaluating the noise performance of a tire according to the present invention 1 or 2. [4th Invention] The method for evaluating the noise performance of a tire according to any one of the present invention 1 to 3, wherein the amount of slip at a plurality of contact points is measured in the second step. [5th ​​Invention] The method for evaluating the noise performance of a tire according to the present invention, wherein in the second step, the average value of the amount of slip at a plurality of contact points is calculated. [Invention 6] The method for evaluating the noise performance of a tire according to any one of invention 1 to 5, wherein the second step involves measuring the amount of slip from the contact point center, which is an intermediate position in the circumferential direction of the tire between the contact point entry and contact point exit, to the contact point exit. [7th Invention] The first step described above is performed indoors. The method for evaluating the noise performance of a tire according to any one of the present invention 1 to 6, wherein the first step uses the tire whose temperature is controlled at room temperature. [8th Invention] The method for evaluating the noise performance of a tire according to the present invention, wherein the interior of the room is controlled to a predetermined room temperature. [Invention 9] The method for evaluating the noise performance of a tire according to the present invention, wherein in the first step, a tire that has been heated to a temperature higher than room temperature by a temperature control device, or a tire that has been heated to a temperature lower than room temperature by a temperature control device, is used. [Explanation of Symbols]

[0035] 2 Simulated road surface K grounding point S slip amount S1 1st process S2 2nd process S3 Evaluation Process T-tire

Claims

1. A method for evaluating the noise performance of tires, The first step involves accelerating the tires on a simulated road surface, During the aforementioned acceleration run, a second step is to measure the amount of circumferential slip of the tire at any point of contact with the simulated road surface of the tire, The process includes, after the second step, an evaluation step of evaluating the noise performance of the tire during acceleration based on the amount of slip, Methods for evaluating tire noise performance.

2. The aforementioned simulated road surface includes a transparent plate, The method for evaluating the noise performance of a tire according to claim 1, wherein in the second step, the amount of slip is measured by photographing the contact point through the transparent plate.

3. The method for evaluating the noise performance of a tire according to claim 2, wherein in the evaluation step, the smaller the amount of slip, the better the noise performance is evaluated.

4. The method for evaluating the noise performance of a tire according to claim 3, wherein the amount of slip at a plurality of contact points is measured in the second step.

5. The method for evaluating the noise performance of a tire according to claim 4, wherein the second step involves calculating the average value of the amount of slip at a plurality of contact points.

6. The method for evaluating the noise performance of a tire according to claim 3, wherein in the second step, the amount of slip from the center of contact, which is an intermediate position in the circumferential direction of the tire between the point of contact entry and the point of contact exit, to the point of contact exit is measured.

7. The first step described above is performed indoors. The method for evaluating the noise performance of a tire according to any one of claims 1 to 6, wherein the first step uses the tire whose temperature is controlled at room temperature.

8. The method for evaluating the noise performance of a tire according to claim 7, wherein the interior of the room is controlled to a predetermined room temperature.

9. The method for evaluating the noise performance of a tire according to claim 7, wherein in the first step, a tire that has been heated to a temperature higher than room temperature by a temperature control device, or a tire that has been heated to a temperature lower than room temperature by a temperature control device, is used.

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