JP2014181958A - Wet road surface measuring apparatus, measuring method, and test road surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce measurement dispersion by stabilizing a wet state on a test road surface.SOLUTION: A measuring apparatus 10 for measuring characteristics of a tire on a wet road surface includes: a support device 12 for supporting a tire T; a test road surface 14 provided so as to come into contact with the supported tire T from below; and a sensor 16 embedded in the test road surface and measuring physical quantity relating to the state of contact of the tire with a ground. In the measuring apparatus 10, grate-like grooves 38 for adjusting water quantity on the test road surface 14 in a wet state are provided on the test road surface 14. The test road surface 14 is set up to be in a wet state by giving water thereon, the tire T is brought into contact with the test road surface 14 in the wet state and is moved on the test road surface, and the physical quantity relating to the state of contact of the tire with the ground is measured by the sensor 16 embedded in the test road surface.

Description

  The present invention relates to a measuring apparatus and a measuring method for measuring characteristics of a measurement object such as a tire on a wet road surface, and a test road surface used for them.

  Conventionally, various measuring devices have been proposed to measure the characteristics of a tire on a wet road surface, such as a contact force when wet. For example, in Patent Document 1, when a three-component force sensor as a load detector is embedded in a test road surface, it is arranged in a line in a direction perpendicular to the tire traveling direction, Measuring the load distribution is disclosed. In this document, a simulated road surface that simulates an actual road surface is used as a test road surface, specifically, a dense-grained asphalt concrete road surface. It is difficult to manage and it is difficult to keep the wet state constant, which causes measurement variation.

  Patent Document 2 discloses that the thickness of a water film is detected by irradiating infrared light onto a test road surface on which the water film is formed in order to measure the relationship between the water film thickness and the characteristics of the measurement object. Has been. In this document, a pseudo road surface having a surface state equivalent to that of a paved road is used as a test road surface, and it is not easy to keep a wet state constant as in Patent Document 1.

  Patent Documents 3 and 4 disclose a method for evaluating the drainage performance of a tire by photographing a ground contact shape through a transparent plate using a transparent plate such as a glass plate as a test road surface.

  In Patent Document 5, a drain groove is formed on the outer peripheral surface of the drum in order to prevent the endless belt from slipping due to water entering between the drum and the endless belt as a test road surface spanned between a pair of drums. Providing a circumferential groove is disclosed. However, providing a groove on the test road surface is not disclosed.

  By the way, in this type of measuring apparatus, conventionally, a road surface to which a safety walk (a sandpaper-like anti-slip material, a trade name of Sumitomo 3M) is attached is generally used as a test road surface (see Patent Document 6). ). However, on the test road surface where the safety walk is simply pasted, a large amount of water is required to lower the friction coefficient with the rubber within the range of 0.5 to 0.7, which is the friction coefficient with the actual road surface when wet. It is difficult to keep the thickness of the water film on the test road surface (that is, a wet state) constant, which may cause measurement variations.

JP 2005-096595 A JP 2008-175757 A JP 2008-256619 A JP 2012-037334 A JP 2002-039919 A JP 2007-298442 A

  The present invention has been made in view of the above points, and an object thereof is to provide a wet road surface measurement device and a measurement method capable of reducing measurement variation by stabilizing the wet state on the test road surface. And

  The wet road surface measuring device according to the present invention measures the characteristics of a measurement object having a rubber surface on the wet road surface, and is supported by the support means for supporting the measurement object and the support means. A test road surface provided so as to come into contact with the measured object from below, and a sensor embedded in the test road surface to measure a physical quantity related to the ground contact state of the measured object, and is in a wet state A groove for adjusting the amount of water on the test road surface is provided on the test road surface.

  The wet road surface measuring method according to the present invention is a method for measuring characteristics on a wet road surface of a measurement object having a rubber surface, and imparts water to a test road surface provided with a groove for adjusting the amount of water. The measurement object is brought into contact with the test road surface in the wet condition to travel on the test road surface, and a physical quantity relating to the ground contact state of the measurement object is measured by a sensor embedded in the test road surface. Is.

  The test road surface according to the present invention is wetted by applying water to the upper surface, and a measurement object having a rubber surface is brought into contact with the wetted upper surface to determine a physical quantity related to the grounding state of the measurement object. A test road surface used in a wet road surface measurement method for measuring characteristics of the measurement object on the wet road surface by measuring, wherein a groove for adjusting the amount of water is provided on the upper surface that contacts the measurement object. It is what was done.

  In the measurement apparatus, the measurement method, and the test road surface, the groove may be a lattice-shaped groove in which a plurality of grooves intersect at right angles or obliquely. In this case, the test road surface may be formed of tiles, and the lattice-shaped grooves may be formed by joint portions of the tiles.

  In the measurement apparatus, the measurement method, and the test road surface, the measurement object may be a tire, and the lattice-shaped grooves may be provided to be inclined with respect to the traveling direction of the tire. Further, the lattice-like grooves may be provided symmetrically with respect to the center line in the width direction of the road surface. The sensor may have a flat upper surface that forms a contact surface with the measurement object, and a drainage channel may be provided around the sensor.

  According to the present invention, since the groove is provided on the test road surface, when water is applied to make the wet state, excess water flows into the groove and the amount of water on the test road surface is adjusted. Can be stabilized. Therefore, it is possible to reduce the measurement variation in characteristics of the measurement object on the wet road surface.

It is a side view of the measuring device concerning one embodiment. It is a perspective view of the test road surface of the measuring device. It is sectional drawing of the test road surface. It is a top view of the test road surface. It is an expanded sectional view around the sensor on the same test road surface. It is an enlarged plan view around the sensor of the test apparatus. It is an enlarged plan view of the test road surface concerning other embodiments. It is an enlarged plan view of the test road surface concerning other embodiment.

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

  The measuring apparatus 10 according to the embodiment measures characteristics on a wet road surface of a tire T as a measurement object. As shown in FIG. 1, the measuring device 10 is provided so as to come into contact with the tire T supported by the support device 12 from below and a support device (support means) 12 that rotatably supports the tire T. A test road surface 14 and a sensor 16 that is embedded in the test road surface 14 and measures a physical quantity related to the ground contact state of the tire T are provided.

  The support device 12 includes a shaft 18 to which the tire T can be attached, and a support arm 20 that rotatably supports the shaft 18. The support arm 20 is configured to be able to move the shaft 18 in the vertical direction, and the tire T can be pressed against the test road surface 14 with an arbitrary load (pressing force) by moving the shaft 18 up and down. .

  The support device 12 is provided with a moving device (moving means) 22 so that the tire T travels on the test road surface 14. More specifically, a moving rail 24 extending along the longitudinal direction is provided above the test road surface 14, and the support device 12 is suspended from a drive unit 26 that travels on the moving rail 24. Therefore, the tire T can be rolled on the fixed test road surface 14 by running the drive unit 26 on the moving rail 24. Instead of moving the support device 12 and rolling the tire T in this way, the support device 12 is fixed and the test road surface 14 is moved so that the tire T travels on the test road surface 14. It may be configured. That is, in the present invention, running the tire on the test road surface includes a mode in which the position of the test road surface is fixed and the tire is moved, and a mode in which the position of the tire is fixed and the test road surface is moved.

  The test road surface 14 has a flat plate shape extending along the moving direction of the moving device 22 and is mounted on the support base 28 in a fixed state. As shown in FIG. 2, the test road surface 14 stabilizes the rolling state of the tire T when passing through the sensor road surface region 30 for measuring the physical quantity by the embedded sensor 16 and the sensor road surface region 30. The approaching road surface area 32 is set longer than the sensor road surface area 30 in this example.

  As shown in FIGS. 3 and 4, the test road surface 14 includes a flat road surface material 34 that forms a road surface (upper surface) on which the tire T contacts the ground, and a support frame 36 that supports the road surface material 34. The road surface material 34 is placed on the top plate 36 </ b> A of the support frame 36.

  The test road surface 14 is provided with a groove 38 for adjusting the amount of water on the test road surface 14 in a wet state. That is, the groove 38 drains excess water on the test road surface 14 and drains the water on the test road surface 14 so that a water film formed by being applied to the test road surface 14 by spraying or the like has a certain thickness. It is a drain for adjusting and a groove for adjustment. The groove 38 is provided on the upper surface of the road surface material 34.

  The groove 38 provided on the test road surface 14 is a lattice-like groove in which a plurality of grooves 38A and 38B intersect at right angles or obliquely. In this example, as shown in FIG. 4, the groove 38 includes a plurality of linear first grooves 38A provided in parallel to each other at regular intervals, and perpendicularly intersects the first grooves 38A. A plurality of linear second grooves 38B provided in parallel with each other at a constant interval are formed in an orthogonal lattice shape having a grid pattern.

  The lattice-shaped grooves 38 are provided to be inclined with respect to the traveling direction S of the tire T. Specifically, the first groove 38A and the second groove 38B constituting the lattice-shaped groove 38 are inclined with respect to the center line M in the width direction of the test road surface 14 extending along the traveling direction S of the tire T. ing. The inclination angle, that is, the angles θ1 and θ2 (see FIG. 6) formed by the first groove 38A and the second groove 38B with respect to the width direction center line M are preferably 10 ° to 80 ° in absolute value, more The angle is preferably 30 ° to 60 °, and is set to 45 ° in this example. The first groove 38A and the second groove 38B are inclined in the opposite direction with respect to the tire traveling direction S.

  Further, as shown in FIG. 4, the lattice-shaped grooves 38 are provided symmetrically with respect to the center line M in the width direction of the test road surface 14. When traveling the tire T, as shown in FIG. 2, the equator line C of the tire T (that is, the center line in the width direction of the tire) is caused to roll in alignment with the center line M in the width direction of the test road surface 14. The grid-like grooves 38 on the test road surface 14 are formed symmetrically with respect to the tire equator line C.

  In the present embodiment, the test road surface 14, specifically the road surface material 34, is formed of tiles, and the lattice-shaped grooves 38 are formed by joint portions of the tiles. Each element 40 of the tile surrounded by the groove 38 has a rectangular shape, more specifically a square shape in this example. Examples of the tile material include ceramics and concrete. The groove 38 forming the joint portion may be made of a material different from that of each element 40 of the tile, but may be integrally formed of the same material. The surface of each element 40 of the tile may be a glossy smooth surface, or may be a rough surface with minute irregularities. Although it does not specifically limit, it is preferable that the maximum friction coefficient (micro | micron | mu) with respect to the tread rubber of a tire is 0.2-0.7, More preferably, it is 0.4-0.6.

  The dimensions of the lattice-shaped grooves 38 (that is, the first grooves 38A and the second grooves 38B) are not particularly limited, but a water flow path when contacting the tire T is secured, and measurement variations are more effectively reduced. In doing so, it is preferable to set as follows. That is, the width w1 (see FIG. 6) of the groove 38 is preferably 3 mm or less, more preferably 1 to 3 mm. Moreover, it is preferable that the depth d1 (refer FIG. 5) is 3 mm or less, More preferably, it is 1-3 mm. Further, the interval between the grooves 38 (that is, the interval between the adjacent first grooves 38A and the interval between the adjacent second grooves 38B) w2 (see FIG. 6) is preferably 10 to 50 mm, more preferably. Is 15-30 mm.

  As the sensor 16, the vertical direction (up and down direction), the front and rear direction (tire traveling direction S), and the left and right direction (in order to measure the ground contact force of the tire T on the wet road surface as a physical quantity related to the ground contact state of the tire T) A three-component force sensor that can detect forces in three directions (in the tire width direction) can be used. In this embodiment, since it is used on the test road surface 14 in a wet state, a sensor 16 that has been waterproofed is used as the sensor 16 so that the waterproofness of internal components and wiring is ensured even under a tire load.

  The sensor 16 is embedded in a state exposed from the upper surface of the test road surface 14 so as to come into contact with the tire T. In this example, as shown in FIGS. 2 and 4, the sensor 16 has a width in a sensor road surface region 30. It is provided on the direction center line M.

  As shown in FIG. 3, the sensor 16 includes a sensor case 42 having a cylindrical upper portion 42 </ b> A, and a sensor portion 44 that protrudes upward from the upper portion 42 </ b> A of the sensor case 42 and constitutes a contact portion with the tire T. . The sensor case 42 is fixed to the lower surface of the top plate 36A of the support frame 36 of the test road surface 14 using a fastener 46 such as a screw. The top plate 36A and the road surface member 34 are provided with a through hole 48 penetrating in the vertical direction. By inserting the cylindrical upper portion 42A of the sensor case 42 into the through hole 48 from below, the sensor unit 44 is It is exposed on the upper surface of the test road surface 14.

  The sensor portion 44 has a solid cross-sectional shape, and therefore, an upper surface 44A that forms a contact surface with the tire T is formed flat. The cross-sectional shape of the sensor portion 44 is rectangular (square) in this example, but may be circular.

  As shown in FIGS. 5 and 6, a drainage channel 50 is provided around the sensor 16, specifically around the upper part 42 </ b> A of the sensor case 42 and the sensor part 44 protruding therefrom. The drainage channel 50 is a flow path for discharging excess water on the sensor 16 downward so that the water film formed on the upper surface 44A of the sensor 16 has a constant thickness (that is, the amount of water is constant). The drainage channel 50 is formed so as to surround the entire periphery of the sensor 16, and is formed by a gap between the outer peripheral surface of the sensor 16 and the inner peripheral surface of the through hole 48. Although the width w3 (refer FIG. 6) of the drainage channel 50 is not specifically limited, It is preferable that it is 3 mm or less, More preferably, it is 1-3 mm.

  In this example, as shown in FIG. 6, the drainage channel 50 around the sensor 16 is connected to the groove 38 of the test road surface 14, so that the upper surface 44 </ b> A of the sensor 16 and the excess from the test road surface 14 around the sensor 16. It is possible to enhance the water draining effect and make the wet state more uniform.

  Next, a method for measuring tire characteristics on a wet road surface using the measuring device 10 will be described.

  First, water is applied to the test road surface 14 to make it wet. The application of water to the test road surface 14 can be performed using a water film forming apparatus (not shown) such as a water sprayer (spray). Such a water film forming apparatus is, for example, attached to the moving rail 24 and provided so as to be movable in the longitudinal direction of the test road surface 14, and while moving above the test road surface 14, a certain amount of the whole in the longitudinal direction. The water may be sprayed. Moreover, you may make it spray on the test road surface 14 manually by an operator.

The amount of water to be applied on the test road surface 14 is not particularly limited, but may be a wet surface (water depth of 1 mm or less), for example 0.01 to 0.1 mL / cm ² , Moreover, it is good also as 0.015-0.025 mL / cm < ² > as other embodiment.

  After the test road surface 14 is in a wet state as described above, the tire T is brought into contact with the test road surface 14 to travel on the test road surface 14 as shown in FIG. 1, and the sensor 16 embedded in the test road surface 14 causes the tire to be A physical quantity related to the grounding state of T is measured.

  Specifically, the tire T supported by the support device 12 is pressed against the wet test road surface 14 with a predetermined load by moving the shaft 18 downward by the support arm 20 and is grounded. At that time, as shown in FIG. 2, the tire T is grounded to the end portion on the side of the running road surface region 32 in the test road surface 14, and the equator line C of the tire T is connected to the center line M in the width direction of the test road surface 14. Ground to match.

  The tire T is caused to travel on the test road surface 14 by the moving device 22 while being grounded in this way. That is, the tire T rolls from the running road surface area 32 toward the sensor road surface area 30 in a state where the equator line C coincides with the center line M in the width direction of the test road surface 14 on the test road surface 14 in a wet state. .

  Then, in the sensor road surface region 30, the tire T has a center portion in the width direction including the equator line C in contact with the sensor portion 44 of the sensor 16, whereby the contact force of the tire T on the wet road surface is measured. The Specifically, the three-component force sensor can detect three directions of force (pressure) in the vertical direction (up and down direction), the front and rear direction (tire traveling direction S), and the left and right direction (tire width direction). . Thereby, for example, the maximum friction coefficient can be calculated, the friction coefficient from the stepping-in to the kicking-out during tire rolling can be detected, and the peak value can be detected.

  In the present embodiment configured as described above, by providing the drainage / adjustment groove 38 on the test road surface 14, when water is sprayed to make it wet, excess water can be released to the groove 38. . Therefore, the amount of water on the test road surface 14 (particularly, the amount of water on the land portion 40 between the grooves 38 with which the tire T comes into contact) can be made constant, and the wet state can be stabilized and the wet surface of the tire T can be stabilized. It is possible to reduce the measurement variation of characteristics at Further, in the present embodiment, since the grooves 38 are provided in a lattice shape as described above, any excess water on the land portion 40 can be transferred to any groove 38 surrounding the entire circumference of the land portion 40. Since it can escape also to a direction, the effect of making water quantity constant can be heightened.

  In the present embodiment, since the lattice-like grooves 38 are provided so as to be inclined with respect to the traveling direction S of the tire T, the grooves 38 on the test road surface 14 coincide with the grooves provided on the tread of the tire T. Can be prevented. In addition, since the grid-like grooves 38 are provided symmetrically with respect to the center line M in the width direction of the test road surface 14, measurement variations can be further reduced.

  In the present embodiment, since the test road surface 14 is formed of tiles, the coefficient of friction with rubber can be reduced compared to the case where a safety walk is used as a road surface material, for example, and it is close to a wet road of an actual vehicle. It is easy to set in the range of μ = 0.5 to 0.7, which is the state of friction coefficient. Here, the value of the coefficient of friction is not a hydro state where the water film is thick and the tire is floating, but a wet state where the amount of water is smaller than that, and this embodiment is advantageous for measurement in such a wet state. Available. If a test road surface is provided with a groove, a safety walk can be used as a road surface material. However, when a safety walk is used, in order to reduce the coefficient of friction when wet to a value equivalent to the actual vehicle wet road, Water is required, and durability of the safety walk is difficult to ensure due to the material used. Therefore, from this point, it is preferable to use tiles as the road surface material.

  In the present embodiment, the sensor portion 44 has a solid cross-sectional shape, and the upper surface 44A that forms a contact surface with the tire T is formed flat, so that the sensor is in contact with the tire T. It is easy to maintain a water film between the tire 16 and the tire T. That is, for example, in a sensor having an annular cross section, the water film is broken through when the sensor comes into contact with the tire, and it is difficult to maintain the water film between the tire and the sensor, but the solid upper surface 44A is flat. A water film can be maintained between the tire T and the sensor 16.

  In this embodiment, since the drainage channel 50 is provided around the sensor 16, it is easy to maintain a constant amount of water film formed on the upper surface 44 </ b> A of the sensor 16.

  In the above-described embodiment, the grid-like grooves 38 provided on the test road surface 14 have a grid-like shape in which the plurality of first grooves 38A and the second grooves 38B intersect each other vertically. The form of crossing is not limited to the case of crossing in an X shape, but may be the case of crossing in a T shape as shown in FIG. That is, in the embodiment of FIG. 7, a plurality of linear first grooves 38A provided in parallel with each other at regular intervals, and a plurality of linear second grooves 38B intersecting with each other in a T shape, A lattice-shaped groove 38P is formed. Further, the lattice-shaped grooves 38 are not limited to the orthogonal lattice shape in which the first grooves 38A and the second grooves 38B intersect perpendicularly, and the first grooves 38A and the second grooves 38B are inclined as shown in FIG. It may be a distorted lattice-like groove 38Q that intersects.

  Moreover, in the said embodiment, although the tire was mentioned as an example as a measuring object, the various objects which have a rubber-made surface can be used as a measuring object. For example, a rubber block sample or the like can be used in addition to a material having a rubber outer peripheral surface such as a disk-shaped member having a rubber sheet attached to the outer peripheral surface or a rubber disk-shaped member.

  In the above embodiment, the case where the sensor 16 is embedded in the test road surface 14 has been described. However, the sensor is not limited to the case where the sensor 16 is embedded in the test road surface. For example, the sensor 16 may be provided on the measurement object side such as a tire or a block sample. Good. When the sensor is provided on the test road surface, characteristics such as a local friction coefficient in the sensor portion can be measured, which is preferable. On the other hand, when the sensor is provided on the measurement object side, the frictional force applied to the entire measurement object can be measured. Here, when a sensor is provided on the measurement object side, for example, in the case of a tire, the sensor can be attached to the axle. For example, in the case of a rubber block sample, the sensor may be attached to a surface (that is, an upper surface) opposite to the ground contact surface with respect to the test road surface. Although not enumerated one by one, various modifications can be made without departing from the spirit of the present invention.

  The effect by this embodiment was confirmed as follows.

(Test Example 1)
A rubber block sample (3 cm × 3 cm × thickness 1 cm) as an object to be measured was grounded to a wet test road surface (directly above the sensor), and the maximum friction coefficient was measured by applying a longitudinal displacement. The wet state was reproduced by spraying tap water with a spray so that the distribution was 0.018 ± 0.003 mL / cm ² with respect to the test road surface. The configuration of the test road surface is as shown in Table 1 below. In Comparative Examples 1 and 2, a safety walk was used as the road surface material, and no groove was provided. In Examples 1 to 7, tiles were used as the road surface material, and the groove width w1, depth d1, interval w2, and angles θ1 and θ2 were set as shown in Table 1. Here, the angle of the groove is an angle of the first groove 38A and the second groove 38B with respect to the traveling direction S of the measurement object (that is, the traveling direction S is 0 °), and is expressed as θ1 × θ2. Further, as for the sensor embedded in the test road surface, in Comparative Example 1, an annular hollow sensor (that is, an annular cross section) (outer diameter = 8 mm) was used, and no drainage channel was provided around the sensor. In Comparative Example 2 and Examples 1 to 7, a sensor having a solid cross section with a flat upper surface (that is, a square solid (7 mm × 7 mm)) as in the above-described embodiment is used, and the sensors described in Table 1 are provided around the sensor. A drainage channel having a width w3 was provided.

  The number of measurements was 10 and the maximum friction coefficient was evaluated. Specifically, the block sample is grounded at a contact pressure of 300 kPa, and is displaced in the front-rear direction. At that time, the front-rear force Fx and the load Fz applied to the block sample are applied to the surface on which the displacement in the rubber block is applied (that is, rubber). The maximum friction coefficient μ (Fx / Fz) with respect to the displacement was calculated by detection with a sensor attached to the upper surface of the block. This means that the μ is closer to the wet road of the actual vehicle as it is in the range of 0.5 to 0.7 or closer thereto. The results are shown in Table 1.

(Test Example 2)
In Examples 1 to 7, using the measurement device 10 according to the above-described embodiment, the tire T is rolled on the test road surface 14 so as to pass over the sensor 16, and the local force ( The change in pressure) was detected by the sensor 16, and the peak value of the front-rear pressure was evaluated. The configurations of the test road surface 14 and the sensor 16 are the same as those in Test Example 1, and are as shown in Table 1. In Comparative Examples 1 and 2, the configuration of the test road surface 14 was a safety walk without a groove as in Test Example 1, and the sensor 16 was configured as shown in Table 1 as in Test Example 1.

The wet state was reproduced by spraying tap water with a spray so that the distribution was 0.018 ± 0.003 mL / cm ² with respect to the test road surface. In that case, water was sprayed not only on the sensor road surface area 30 but also on the running road surface area 32 to reproduce the same wet state.

  The number of tests was 10, and water spraying was performed for each test. On the tire side, water drops were wiped off for each test to make it dry. The test conditions were tire size: 195 / 65R15, tire internal pressure: 220 kPa, load: 5.0 kN, longitudinal force: braking direction 1.5 kPa, and the sensor measurement position was the tire center as in the above embodiment. As a result, the friction coefficient from the stepping on the tire to the kicking is monitored, the standard deviation is calculated as the variation of the number of tests 10 times (N = 10) for the peak value (peak μ), and the standard deviation of Comparative Example 1 is calculated. Evaluation was made with an index of 100. The smaller the index, the smaller the standard deviation and the smaller the measurement variation. The results are shown in Table 1.

(Discussion)
As shown in Table 1, in Comparative Example 1, a safety walk without a groove was used as a road surface material, and a sensor having an annular cross section was used. Therefore, the maximum friction coefficient μ in a wet state was a target value of 0.5 to 0. Much larger than .7. In Comparative Example 2, although a solid cross-section sensor was used and a drainage channel was provided around it, a safety walk without a groove was used as a road surface material, so the measurement variation of the peak μ on the tire was large, and a rubber sample was used. The maximum friction coefficient μ was also larger than the target value.

  On the other hand, in Examples 1-7, the use of tiles with grooves as the road surface material has reduced the measurement variation of the peak μ in the tire compared to Comparative Example 1, and the maximum wet state The friction coefficient μ is also within or close to the target value of 0.5 to 0.7, and good results were obtained. In Example 1, since the groove of the tile which is the test road surface 14 is arranged in a direction of 90 ° with respect to the traveling direction, the corner of the rubber is caught in the groove of the tile, and the peak μ is smaller than that in Example 2. Was high. By providing the grooves with an inclination relative to the traveling direction, the peak μ could be reduced to 0.7 or less as shown in Examples 2 to 7.

  Further, as shown in Examples 3 to 7, the groove on the test road surface has a smaller maximum friction coefficient μ in the wet state as the width and depth thereof are larger, and the peak μ in the tire is smaller. The variation in measurement was also reduced.

DESCRIPTION OF SYMBOLS 10 ... Measuring apparatus 12 ... Supporting device 14 ... Test road surface 16 ... Sensor 38 ... Groove 50 ... Drainage channel T ... Tire S ... Tire progress direction M ... Test road surface width direction center line

Claims (13)

A wet road surface measuring device for measuring characteristics on a wet road surface of a measurement object having a rubber surface,
A support means for supporting the measurement object; a test road surface provided to contact the measurement object supported by the support means from below; and a grounding surface of the measurement object embedded in the test road surface A sensor for measuring a physical quantity related to the state,
A wet road surface measuring device, wherein a groove for adjusting the amount of water on the test road surface in a wet state is provided on the test road surface.   The wet road surface measuring device according to claim 1, wherein the groove provided on the test road surface is a lattice-like groove in which a plurality of grooves intersect at right angles or obliquely.   3. The wet road surface measuring device according to claim 2, wherein the test road surface is formed of a tile, and the lattice-shaped groove is formed by a joint portion of the tile.   The wet road surface measuring device according to claim 2 or 3, wherein the object to be measured is a tire, and the lattice-shaped grooves are inclined with respect to the traveling direction of the tire.   The wet road surface measuring device according to any one of claims 2 to 4, wherein the grid-like grooves are provided symmetrically with respect to a center line in the width direction of the test road surface.   The wetness according to any one of claims 1 to 5, wherein the sensor has a flat upper surface forming a contact surface with the measurement object, and a drainage channel is provided around the sensor. Road surface measuring device. A wet road surface measuring method for measuring characteristics on a wet road surface of a measurement object having a rubber surface,
Water is applied to a test road surface provided with a groove for adjusting the amount of water to make it wet, and the measurement object is brought into contact with the test road surface in a wet state to run on the test road surface. A wet road surface measuring method, characterized in that a physical quantity relating to the ground contact state of the measurement object is measured by an embedded sensor.   The wet road surface measuring method according to claim 7, wherein the groove provided on the test road surface is a lattice-like groove in which a plurality of grooves intersect at right angles or obliquely.   9. The wet road surface measuring method according to claim 8, wherein the test road surface is formed by a tile, and the lattice-shaped grooves are formed by joint portions of the tile.   The wet road surface measuring method according to claim 8 or 9, wherein the object to be measured is a tire, and the lattice-shaped grooves are inclined with respect to the traveling direction of the tire.   The wet road surface measuring method according to any one of claims 8 to 10, wherein the grid-like grooves are provided symmetrically with respect to a center line in the width direction of the test road surface.   The wetness according to any one of claims 7 to 11, wherein the sensor has a flat upper surface forming a contact surface with the measurement object, and a drainage channel is provided around the sensor. Road surface measurement method. Applying water to the upper surface to make it wet, bringing the measurement target having a rubber surface into contact with the wet upper surface, and measuring the physical quantity related to the grounding state of the measurement target, thereby measuring the measurement target A test road surface used in a wet road surface measuring method for measuring characteristics on a wet road surface of an object,
A test road surface characterized in that a groove for adjusting the amount of water is provided on the upper surface with which the measurement object is brought into contact.

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