JP6812253B2 - Evaluation method of tire ground contact characteristics - Google Patents

Description

The present invention relates to a method for evaluating tire ground contact characteristics.

Conventionally, as a method for evaluating the ground contact characteristics of a tire, the tire is placed on a flat plate that is transparent to visible light, and with a predetermined load applied, visible light is irradiated from the lower side of the flat plate and reflected. Some detect light (see, for example, Patent Document 1).

Patent No. 3406643

Here, the actual road surface is paved with asphalt or concrete, or unpaved stone, sand, and soil, and since the vehicle runs on these, the ground contact characteristics of the tire on the road surface having predetermined unevenness It is desirable to evaluate. However, in the above method, when a flat plate having unevenness is used, it may be difficult to evaluate the ground contact characteristics of the tire on the flat plate having unevenness due to the unevenness scattering visible light.

In view of such circumstances, it is an object of the present invention to provide a method for evaluating tire ground contact characteristics, which can evaluate the ground contact characteristics of a tire on a flat plate even when the flat plate has predetermined irregularities. ..

The gist structure of the present invention is as follows.
In the method for evaluating the tire contact characteristics of the present invention, the tire is placed on one surface of a flat plate.
A predetermined load is applied to the tire or the tire is placed in a no-load state, and the tire is irradiated with a terahertz wave having a frequency of 0.1 THz to 10 THz from the other surface side of the flat plate or from the inside of the flat plate. The wavelength of the terahertz wave is larger than the average roughness length of at least a part of one surface of the flat plate, the reflected wave of the terahertz wave from the tire is detected, and the tire is based on the result of the detection. It is characterized by evaluating the characteristics of the tire when it is grounded.
According to this method, even when the flat plate has predetermined unevenness, the ground contact characteristics of the tire on the flat plate can be evaluated.

In the method for evaluating the tire contact characteristics of the present invention, the tire is placed on one surface of the flat plate.
A predetermined load is applied to the tire, or the tire is placed in a no-load state.
The tire is irradiated with a terahertz wave having a frequency of 0.1 THz to 10 THz from the other surface side of the flat plate or from the inside of the flat plate, and the wavelength of the terahertz wave is at least one of the one surfaces of the flat plate. Roughness larger than the average length RSm of the roughness curve element with a reference length of 0.8 mm defined by JIS B0601 or coarse with a reference length of 0.25 mm as defined by JIS B0601 Greater than the average length RSm of the curve element,
The reflected wave of the terahertz wave from the tire is detected,
It is preferable to evaluate the characteristics of the tire when it touches the ground based on the result of the detection.
According to this method, the ground contact characteristics of the tire on the flat plate can be evaluated even when the flat plate has irregularities having the predetermined RSm.

In the method for evaluating the tire contact characteristics of the present invention, it is preferable to detect the reflected wave of the terahertz wave on the surface.
According to this method, the movement of a certain point can be easily observed and the movement of the tread surface can be easily measured.

In the method for evaluating the tire contact patch of the present invention, a substance having a terahertz wave absorption rate or reflectance higher or smaller than that of the rubber is attached to the surface of the rubber serving as the contact patch of the tire.
It is preferable to include detecting the position of the substance by detecting the position where the intensity of the detected terahertz wave is increased or decreased with respect to the surroundings.
According to this method, the movement of the tread surface can be measured more accurately by easily identifying the position of the substance.

In the method for evaluating the tire ground contact characteristic of the present invention, an image showing the position where the detected terahertz wave intensity is increased or decreased with respect to the surroundings is acquired.
It is preferable to derive the distribution of the position of the substance in the ground plane from the acquired image.
According to this method, the movement of the identification point, which is the point where the substance is attached, can be measured more accurately.

In the method for evaluating the tire ground contact characteristic of the present invention, the distribution of the positions is the center of gravity position obtained from the area weighted by the intensity of the reflected wave from the substance, the centroid position obtained from the area, and the distribution range. It is preferable to contain at least one of.
According to this method, the movement of the identification point, which is the point where the substance is attached, can be measured with good accuracy.

According to the present invention, it is possible to provide a method for evaluating a tire ground contact characteristic that can evaluate the ground contact characteristic of a tire on the flat plate even when the flat plate has predetermined unevenness.

It is a figure which shows typically the evaluation apparatus of the tire ground contact characteristic used in the evaluation method of the tire ground contact characteristic on a flat plate having a predetermined unevenness which concerns on one Embodiment of this invention. It is a figure which shows typically the evaluation apparatus of the tire ground contact characteristic used in the evaluation method of the tire ground contact characteristic on a flat plate having a predetermined unevenness of another example which concerns on one Embodiment of this invention. It is a figure which shows typically the evaluation apparatus of the tire ground contact characteristic used in the tire ground contact characteristic evaluation method on a flat plate having a predetermined unevenness of another example which concerns on one Embodiment of this invention. This is an example of an image showing the movement of an identification point, which is a point to which a substance is attached. This is an example of an image showing the movement of the identification point, which is a point with a substance, and the distribution of the position of the identification point.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram schematically showing a tire ground contact characteristic evaluation device used in the ground contact characteristic evaluation method for a tire on a flat plate having a predetermined unevenness according to an embodiment of the present invention. As shown in FIG. 1, the tire ground contact characteristic evaluation device 1 includes a flat plate 2, an irradiation device 3 for irradiating a terahertz wave, a force sensor 4, and a reflected wave detection device 5.

In the present embodiment, the flat plate 2 is an acrylic plate that is transparent to visible light. In this example, the flat plate 2 has irregularities formed on one surface (upper surface of FIG. 1) that simulates an actual road surface. The other surface (lower surface of FIG. 1) of the flat plate 2 is formed to be flat as a whole. However, since it is not possible to completely eliminate the unevenness in engineering, in reality, extremely minute unevenness is formed. Specifically, in this example, one surface (upper surface in FIG. 1) has an average length RSm of a roughness curve element having a reference length of 0.8 mm, which is defined by JIS B0601, of 0.13. The average length RSm of the roughness curve element, which is ~ 0.4 mm and the reference length is 0.25 mm, is 0.04 to 0.13 mm. On the other hand, the other surface (lower surface in FIG. 1) has an average length RSm of a roughness curve element having a reference length of 0.08 mm, which is defined by JIS B0601, of 13 to 40 μm.

In the example shown in FIG. 1, the irradiation device 3 is arranged on the lower side (the other surface side) of the flat plate 2, and is arranged from the other surface (lower surface side of FIG. 1) side of the flat plate 2 to one surface (FIG. 1). It is arranged so that the terahertz wave can be irradiated toward the upper surface) side. As the irradiation device 3, any known device capable of irradiating a terahertz wave having a frequency of 0.1 THz to 10 THz can be used.

In this example, the force sensor 4 places the tire 6 on one surface (upper surface of FIG. 1) of the flat plate 2, applies a predetermined load, and makes the tire 6 relative to the flat plate 2 on the flat plate 2. It is possible to measure the pressure and the shearing force τ when the tire is rotated. In this case, as the force sensor 4, any known pressure sensor or shear force sensor, or a pressure / shear force sensor capable of measuring pressure and shear force can be used. In this example, the force sensor 4 is configured to be partially embedded inside the flat plate 2. In the present invention, instead of the force sensor 4, a device for measuring other characteristics may be provided, or a force sensor 4 or the like may not be provided.

The reflected wave detection device 5 detects the reflected wave of the terahertz wave from the tire 6 that is reflected by the tire 6. As the reflected wave detection device 5, any known device can be used. In this example, since the irradiation device 3 is arranged on the lower side of the flat plate 2 and the tire 6 is arranged on one surface (upper surface of FIG. 1) of the flat plate 2, the reflected wave detection device 5 is terahertz. It is arranged on the lower side of the flat plate 2 so that the reflected wave of the wave can be detected. On the other hand, the arrangement of the reflected wave detection device 5 is not limited to this example, and in short, the arrangement may be such that the reflected wave of the terahertz wave from the tire 6 can be detected.

In the method of the present embodiment, as shown in FIG. 1, first, the tire 6 is placed on one surface (upper surface of FIG. 1) of the flat plate 2 and a predetermined load is applied to the tire 6. The tire 6 is rim-assembled in this example, and the rim is, for example, an industrial standard that is effective in the area where the tire is produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK, Europe. ETRTO (The European Tire and Rim Technical Organization) STANDARDS MANUAL, in the United States TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK, etc. STANDARDS MANUAL refers to the Tirering Rim, TRA's YEAR BOOK refers to the Design Rim) (ie, the "rim" above includes sizes that may be included in the industry standards in the future in addition to the current size. As an example of "the size described", the size described as "FUTURE DEVELOPMENTS" in the STANDARDS MANUAL 2013 edition of ETRTO can be mentioned.) If the size is not described in the above industrial standard, the tire A rim with a width corresponding to the bead width of. Further, in this example, the rim-assembled tire 6 is filled with internal pressure, and the internal pressure is, for example, the maximum load capacity of a tire of a standard such as JATMA in a tire of an applicable size by mounting the tire on the applicable rim. The air pressure corresponding to (maximum air pressure) can be set. In the case of a size not described in the above industrial standard, it means the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle equipped with tires. Further, the "predetermined load" can be, for example, the maximum tire load capacity of a standard such as JATMA. Alternatively, it can be arbitrarily set according to the purpose of ground contact characteristic evaluation such as 0.8 times or 0.9 times the maximum tire load capacity. In the present embodiment, a predetermined load is applied to the tire 6, but for example, when evaluating the ground contact state at the time of no load, the tire 6 can be set to the no-load state. The air can also be replaced with an inert gas such as nitrogen gas.

Next, the tire 6 is rotated on the flat plate 2 relative to the flat plate 2. Although not shown, any known device capable of rotating the tire 6 about an axis can be used for the rotation of the tire 6. Further, when the tire 6 is relatively rotated on the flat plate 2, the flat plate 2 may be moved while the tire 6 is stationary so as to be rotatable about an axis, while the flat plate 2 may be moved. May be stationary and the tire 6 may be rolled on the stationary flat plate 2. Further, both the flat plate 2 and the tire 6 may be moved so that the tire 6 is relatively rotated on the flat plate 2. Further, in either case, the irradiation device 3 and the reflected wave detection device 5 can be stationary or moved. In these cases, although not shown, any known device capable of moving the flat plate 2, the irradiation device 3, the reflected wave detection device 5, and the tire 6 can be used.

Then, a terahertz wave having a frequency of 0.1 THz to 10 THz is applied to the tire 6 from the irradiation device 3 located on the other surface (lower surface of FIG. 1) of the flat plate 2 on one surface of the flat plate 2 (FIG. 1). Irradiate toward the tire 6 on the upper surface). In this example, the irradiation device 3 is arranged on the lower side (the other surface side) of the flat plate 2, but the present invention is not limited to this embodiment. In addition, the irradiation device 3 is placed inside the flat plate 2, for example. It may be arranged so that the terahertz wave can be irradiated from the inside of the flat plate 2 toward one surface (upper surface of FIG. 1) of the flat plate 2.

Here, in the present embodiment, the wavelength of the irradiated terahertz wave (0.03 mm to 3 mm for the terahertz wave having a frequency of 0.1 THz to 10 THz) is determined by JIS B0601 which is at least a part of one surface of the flat plate 2. It is greater than the defined average length RSm of the roughness curve element with a reference length of 0.8 mm or the average length RSm of a roughness curve element with a reference length of 0.25 mm. As a result, the irradiated terahertz wave is irradiated to the tire 6 on the flat plate 2 without being scattered by the flat plate 2. Further, since the wavelength of the terahertz wave is larger than the RSm of the lower surface 4b of the unevenness, the terahertz wave reflected by the tire 6 can also travel below the flat plate 2 without being scattered by the flat plate 2.

Next, the reflected wave detection device 5 detects the reflected wave of the terahertz wave from the tire 6. Then, based on the detection result, the characteristics of the tire 6 at the time of touchdown are evaluated. For example, the reflected wave detection device 5 can image the reflected wave of the terahertz wave, and the characteristics of the tire 6 at the time of touchdown can be evaluated from the image.

（Ｓは滑り量、τはせん断力、添字ｘ、ｙは、ｘｙ平面におけるｘ方向、ｙ方向を表す）
τ_ｘ及びτ_ｙは、力センサ４により計測することができる。また、滑り量Ｓは、テラヘルツ波の反射波の検出結果に基づいて導出することができる。従って、本実施形態によれば、力センサ４により計測したせん断力τと導出した滑り量Ｓとにより、タイヤの摩耗エネルギーを算出してタイヤのトレッド摩耗速度Ｗを求めることができる。なお、本実施形態では、「基準長さを０．８ｍｍとした粗さ曲線要素の平均長さＲＳｍ又は基準長さを０．２５ｍｍとした粗さ曲線要素の平均長さＲＳｍ」を粗さ平均長さを用いたが、本発明では、凹凸によりテラヘルツ波が散乱されないのであれば、他の基準長さを用いても良い。 As described above, according to the method of the present embodiment, even when the flat plate 2 has predetermined unevenness, the ground contact characteristics of the tire on the flat plate 2 can be evaluated. For example, in the present embodiment, if the shearing force τ on the ground plane is measured by the force sensor 4, the wear energy can be calculated as follows. That is, the wear rate W of the tread of the tire can be expressed as W = A × E by using the mechanical wear energy E and the proportionality constant A representing the ease of wear of the rubber. Here, E can be expressed by the following equation 1.

(S is the amount of slip, τ is the shearing force, and the subscripts x and y are the x and y directions in the xy plane.)
τ _x and τ _y can be measured by the force sensor 4. Further, the slip amount S can be derived based on the detection result of the reflected wave of the terahertz wave. Therefore, according to the present embodiment, the tire wear energy can be calculated from the shear force τ measured by the force sensor 4 and the derived slip amount S to obtain the tire tread wear speed W. In the present embodiment, "the average length RSm of the roughness curve element having the reference length of 0.8 mm or the average length RSm of the roughness curve element having the reference length of 0.25 mm" is the roughness average. Although the length is used, in the present invention, another reference length may be used as long as the terahertz wave is not scattered due to the unevenness.

FIG. 2 is a diagram schematically showing an evaluation device for tire ground contact characteristics used in the method for evaluating tire ground contact characteristics on a flat plate having predetermined irregularities according to another example according to the embodiment of the present invention. In the example shown in FIG. 2, only the unevenness of the upper surface of the flat plate 2 is different from the example shown in FIG. The unevenness of the lower surface of the flat plate 2 is the same as that in FIG. That is, in the example shown in FIG. 2, large irregularities are formed on the upper surface of the flat plate 2. In the example shown in FIG. 2, the upper surface of the flat plate 2 has a rectangular wave cross-sectional shape, and the length of the upper side of the rectangular wave is 10 mm and the length of the lower side is 10 mm. Further, minute irregularities are formed in the square wave cross-sectional shape, and specifically, the average length RSm of the roughness curve element with the reference length of 0.8 mm is 0.13 to 0.4 mm. The average length RSm of the roughness curve element with the reference length of 0.25 mm is 0.04 to 0.13 mm. Also in the example shown in FIG. 2, the wavelength of the terahertz wave is larger than RSm having the reference length of 0.8 mm or RSm having the reference length of 0.25 mm. According to this, depending on the large unevenness (square wave cross-sectional shape), the terahertz wave is not scattered because the unevenness is sufficiently large, and the minute unevenness (RSm with a reference length of 0.8 mm) within the large unevenness is Since the wavelength of the terahertz wave is larger than the RSm, the terahertz wave has the minute unevenness even if the RSm is 0.13 to 0.4 mm and the reference length is 0.25 mm and the RSm is 0.04 to 0.13 mm. Not scattered by some. The lower surface is the same as the example shown in FIG. Therefore, in the case of the example shown in FIG. 2, the same action and effect as the example shown in FIG. 1 can be obtained. That is, even if large irregularities for evaluating vibration characteristics are formed on any surface of the flat plate 2 (upper surface in FIG. 2), the reference length is 0.8 mm in the end. If the wavelength of the terahertz wave is larger than the average length RSm of the roughness curve element at the viewpoint, the terahertz wave is not scattered by the flat plate 2.

FIG. 3 is a diagram schematically showing a tire ground contact characteristic evaluation device used in another example method for evaluating the ground contact characteristics of a tire on a flat plate having predetermined irregularities according to an embodiment of the present invention. In the example shown in FIG. 3, only the unevenness of the upper surface of the flat plate 2 is different from the example shown in FIG. The unevenness of the lower surface of the flat plate 2 is the same as that in FIG. That is, in the example shown in FIG. 3, the upper surface of the flat plate 2 also has the same average length RSm (0.13 to 0.4 mm) and reference length of the roughness curve elements having a reference length of 0.8 mm as the lower surface. It has an average length RSm (0.04 to 0.13 mm) of the roughness curve element set to 0.25 mm. In the example shown in FIG. 3, the wavelength of the terahertz wave is larger than RSm having the reference length of 0.8 mm or RSm having the reference length of 0.25 mm on the upper surface and the lower surface. Also in this example, since the terahertz wave is not scattered on the upper surface and the lower surface as in the lower surface of FIG. 1, the same effect as the example shown in FIG. 1 can be obtained. Therefore, the present invention can also be used to evaluate the ground contact characteristics of a tire on a flat road surface.

In the example shown in FIG. 1, unevenness simulating an actual road surface is formed only on the upper surface of the flat plate 2, but for example, unevenness having the same roughness may be formed only on the lower surface of the flat plate 2. , Concavities and convexities having the same roughness may be formed on the upper surface and the lower surface of the flat plate 2. In short, as described above, the actual road surface varies from paved road (asphalt, concrete, etc.) and unpaved road (stone, sand, soil, etc.), but a flat plate having predetermined unevenness simulating those unevenness. If 2 is prepared in various ways and the wavelength of the terahertz wave is selected in various ways so as to be larger than RSm having the reference length of 0.8 mm or RSm having the reference length of 0.25 mm of the predetermined unevenness, terahertz The effect of the present invention can be obtained without the wave being scattered on the flat plate 2. Then, in the path from the irradiation of the terahertz wave to the detection of the reflected wave, the terahertz wave does not have to be scattered by the flat plate 2, and therefore, the place where the wavelength of the terahertz wave is larger than RSm is at least a part of the upper surface and at least the lower surface. It will be good if it is in a part. On the other hand, from the viewpoint of evaluating the ground contact characteristics when the tire rolls, the locations where the wavelength of the terahertz wave is larger than RSm can be defined as the entire upper surface and lower surface. When both the irradiation device 3 and the reflected wave detection device 5 are arranged inside the flat plate 2, the portion where the wavelength of the terahertz wave is larger than RSm may be at least a part of one of the surfaces. It will be.

Here, in the present invention, it is preferable to detect the reflected wave of the terahertz wave on the surface. FIG. 4 is an example of an image showing the movement of an identification point (indicated by a black circle in FIG. 4), which is a point to which a substance is attached. As shown in FIG. 4, when the reflected wave is measured on the surface, the movement of the point can be easily measured. On the other hand, for example, when the discrimination point moves, the reflected wave of the terahertz wave can be detected by a line. Further, by following the movement of the identification point, the reflected wave of the terahertz wave can be detected at the point.

Further, in the present invention, a substance having a terahertz wave absorption rate or reflectance larger or smaller than that of the rubber is attached to the surface of the rubber which is the ground contact surface of the tire, and the intensity of the detected terahertz wave is increased as compared with the surroundings. Alternatively, it is preferable to include detecting the position of the substance by detecting the reduced position. Specifically, when the absorption rate of the terahertz wave of the substance is larger than that of rubber, the position where the detected terahertz wave intensity is reduced with respect to the surroundings is detected to detect the position of the substance, and the substance is also detected. When the absorption rate of the terahertz wave is smaller than that of rubber, the position where the detected terahertz wave intensity is increased with respect to the surroundings is detected to detect the position of the substance. When the reflectance of the terahertz wave of the substance is larger than that of rubber, the position where the intensity of the detected terahertz wave is increased with respect to the surroundings is detected to detect the position of the substance, and the terahertz wave of the substance is also detected. When the reflectance of the substance is smaller than that of rubber, the position of the substance is detected by detecting the position where the intensity of the detected terahertz wave is reduced with respect to the surroundings. A part of the terahertz wave penetrates the inside of the tire instead of the surface of the tire and then reflects. Therefore, it may be difficult to distinguish whether the reflected wave is a reflected wave from the tire surface or a reflected wave from the inside of the tire. On the other hand, in the above method, the movement of the tread surface can be measured more accurately by easily identifying the position of the substance. For example, a conductor can be used as the above substance. This is because the terahertz wave is absorbed by the conductor. More specifically, the substances include markings and paints containing metals such as titanium oxide and aluminum, seals containing metals and metal powders that can be attached, and rubbers containing a large amount of conductive carbon black and carbon materials. Various things can be used.

Further, in the present invention, an image showing a position where the intensity of the detected terahertz wave is increased or decreased with respect to the surroundings is acquired, and the distribution of the position of the substance in the ground plane is derived from the acquired image. Is preferable. Since the resolution of the measurement point is about the wavelength, the resolution of the measurement point in the present invention is about the wavelength of the terahertz wave (for example, when the wavelength of the terahertz wave is 0.5 mm, the resolution is about 0.5 mm). Therefore, the movement of the discrimination point can be measured more accurately by deriving the distribution of positions within the possible range with such resolution and taking it into consideration.

Further, in the present invention, the position distribution may include at least one of the center of gravity position obtained from the area, the centroid position obtained from the area, and the distribution range weighted by the intensity of the reflected wave from the substance. preferable. FIG. 5 is an example of an image showing the movement of the identification points, which are the points to which the substance is attached, and the distribution of the positions of the identification points. The upper left and upper right views of FIG. 5 exemplify the movement of the identification points (shown by shaded diagonal lines) when the identification points having a diameter of 1 mm are arranged on the tread surface and observed with a spatial resolution of 0.5 mm. ing. Therefore, in FIG. 5, the size of one square is 0.5 mm × 0.5 mm. In the upper left figure of FIG. 5, the identification points are distributed across the four squares. From there, the identification points move in the upper right direction of the figure, and in the upper right figure of FIG. 5, the identification points are distributed across nine squares. In this way, first, the distribution range in which the identification points are located can be determined from the acquired image. At this time, in the acquired image, all the squares in which the area occupied by the identification points with respect to the squares is larger than 0 can be set as the distribution range of the substance, while the area occupied by the identification points with respect to the squares is a constant value. In the following cases, it can be considered that the substance is not distributed. Further, in the case shown in the upper figure of FIG. 5, the position of the center of gravity and the position of the center of gravity can be obtained from the area weighted by the intensity of the reflected wave from the substance. For example, in the upper right figure of FIG. 5, the surface property is the highest. Large squares can be the center of gravity position and the centroid position. The lower figure of FIG. 5 is a view in which the position of the center of gravity, the position of the center of gravity, and the distribution range are visualized in shades corresponding to the upper view of FIG. In the lower figure of FIG. 5, the entire square is displayed with a predetermined shade for one square, and the shade is determined by the size of the area occupied by the identification point with respect to the square. In this example, if the area occupied by the identification points with respect to the squares is less than a certain level, it is considered to be non-distributed and processed, and the part occupying a large area with respect to the squares is darkened (shaded in the figure). (Part) is shown, and the squares of the parts where the area occupied by the identification point with respect to the squares is relatively smaller than the squares are shown lightly (shaded parts in the figure). In this way, the position of the center of gravity, the position of the center of gravity, and the distribution range can be more visually grasped by, for example, the shading on the image. In this case, it is possible to more visually grasp that the darkest part on the image is the square of the center of gravity position and the center of gravity position. Further, as shown in the upper right figure and the lower right figure of FIG. 5, when the area occupied by the identification points with respect to the squares is almost the same in the four squares, it can be more visualized as the squares having the same density. In this case as well, the position of the center of gravity, the position of the center of gravity, and the distribution range can be grasped more visually. Further, in this case, for example, the position of the center of gravity and the position of the center of gravity when four squares are regarded as one square can be obtained. In this way, by obtaining at least one of the center of gravity position, the centroid position, and the distribution range, the movement of the discrimination point can be measured with favorable accuracy. At that time, as shown in the lower figure of FIG. 5, the movement of the identification point can be grasped more visually by performing the visualization process by shading.

A tire with a tire size of PSR195 / 65R15 and no tread pattern was prototyped. When the tire is incorporated into the applicable rim using the device shown in FIG. 1, the internal pressure is 210 kPa, a load of 4.41 kN is applied, and the tire is rolled on a transparent acrylic plate at a speed of 1 km / h and a slip angle of 1 °. The amount of slippage on the surface of the tire tread was measured. In this embodiment, the tires were stationary so as to be rotatable, and the transparent acrylic plate was moved at a speed of 1 km / h by a moving device.

As Comparative Example 1, a transparent acrylic plate having a flat surface (upper and lower surfaces) (RSm = 20 μm at a reference length of 0.08 mm) was used, irradiated with visible light, and the reflected light was measured with a video camera. As Comparative Example 2, a transparent acrylic plate having an unevenness of RSm = 0.2 mm with a reference length of 0.8 mm on the upper surface (the lower surface is flat) was used, irradiated with visible light, and measured with a video camera. As an example of the invention 1, a transparent acrylic plate having an unevenness of RSm = 0.2 mm with a reference length of 0.8 mm (the lower surface is flat) is used on the upper surface, and a 1 THz terahertz wave (wavelength 0.3 mm) is irradiated to the surface. Was detected by. As Example 2, a transparent acrylic plate having an unevenness of RSm = 0.2 mm with a reference length of 0.8 mm on the upper surface (the lower surface is flat) is used, and a terahertz wave of 0.5 THz (wavelength 0.6 mm) is irradiated. , Surface detection was performed. Here, in Invention Examples 1 and 2, marking was performed with a marking pen containing titanium oxide on the tire surface. In Invention Examples 1 and 2, the slip amount was evaluated by acquiring an image of the marked identification point. Here, since terahertz waves are absorbed by titanium oxide, a region having a lower reflection intensity than the surroundings was measured as an identification point. In Invention Example 1, the position of the center of gravity obtained from the area weighted by the intensity of the reflected wave was obtained, and in Invention Example 2, the position of the center of gravity obtained from the area was obtained and used as the slip amount.

As shown in Table 1, in Comparative Example 2, it is possible to measure the amount of slippage when the tire is kicked out on a transparent acrylic plate having an unevenness of RSm = 0.2 mm at a reference length of 0.8 mm on the upper surface. However, according to Invention Examples 1 and 2, the amount of slippage when the tire is kicked out on a transparent acrylic plate having an unevenness of RSm = 0.2 mm at a reference length of 0.8 mm on the upper surface is measured. You can see that it was possible.

1: Tire ground contact characteristic evaluation device, 2: Flat plate, 3: Irradiation device, 4: Force sensor,
5: Reflected wave detector, 6: Tire

Claims (6)

Place the tire on one side of the flat plate
A predetermined load is applied to the tire, or the tire is placed in a no-load state.
The tire is irradiated with a terahertz wave having a frequency of 0.1 THz to 10 THz from the other surface side of the flat plate or from the inside of the flat plate, and the wavelength of the terahertz wave is at least one of the one surfaces of the flat plate. Roughness larger than the average length of the part,
The reflected wave of the terahertz wave from the tire is detected,
A method for evaluating tire contact characteristics, which comprises evaluating the characteristics of the tire when it touches the ground based on the result of the detection. Place the tire on one side of the flat plate
A predetermined load is applied to the tire, or the tire is placed in a no-load state.
The tire is irradiated with a terahertz wave having a frequency of 0.1 THz to 10 THz from the other surface side of the flat plate or from the inside of the flat plate, and the wavelength of the terahertz wave is at least one of the one surfaces of the flat plate. Roughness of the part, which is larger than the average length RSm of the roughness curve element with a reference length of 0.8 mm defined by JIS B0601, or the roughness with a reference length of 0.25 mm defined by JIS B0601 Greater than the average length RSm of the curve element,
The reflected wave of the terahertz wave from the tire is detected,
The method for evaluating a tire contact characteristic according to claim 1, wherein the characteristic of the tire at the time of contact with the ground is evaluated based on the result of the detection. The method for evaluating a tire ground contact characteristic according to claim 1 or 2, wherein the reflected wave of the terahertz wave is detected on a surface. A substance having an absorption rate or reflectance of the terahertz wave larger or smaller than that of the rubber is attached to the surface of the rubber serving as the ground contact surface of the tire.
The tire according to any one of claims 1 to 3, which comprises detecting the position of the substance by detecting the position where the detected terahertz wave intensity increases or decreases with respect to the surroundings. Evaluation method of grounding characteristics. An image showing the position where the intensity of the detected terahertz wave increased or decreased with respect to the surroundings was acquired.
The method for evaluating a tire contact patch according to claim 4, wherein the distribution of positions of the substance in the contact patch is derived from the acquired image. The distribution of the position according to claim 5, wherein the distribution of the positions includes at least one of the center of gravity position obtained from the area, the centroid position obtained from the area, and the distribution range weighted by the intensity of the reflected wave from the substance. How to evaluate the tire contact characteristics of.

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