Friction testing apparatus and friction testing method

Abstract

To provide a friction testing device and a friction testing method capable of accurately adjusting the temperature of a road surface member.SOLUTION: The frictional test device 100 includes a road surface member 1 having a test road surface 1a in contact with the test rubber body R, a first thermally conductive member 11 in contact with the road surface member 1 directly or indirectly, a liquid tank 2 in which the road surface member 1 and the first thermally conductive member 11 are housed and a liquid Lq is stored, and a liquid temperature adjustment means 3 capable of adjusting the temperature of the liquid Lq. The frictional test method includes a liquid storage step of storing a liquid Lq in a liquid tank 2 accommodating a road surface member 1 having a test road surface 1a and a first thermally conductive member 11 directly or indirectly contacting the road surface member 1, a road surface temperature adjustment step of adjusting a temperature of the road surface member 1 via the stored liquid Lq, and a frictional test step of performing a frictional test of a test rubber body R by relatively moving the test rubber body R with respect to the test road surface 1a.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a friction testing device and a friction testing method. [Background technology]

[0002] A friction test device used to evaluate friction performance of rubber products is one that presses a rubber product or a test piece made of the same rubber against a test road surface member. Since the friction performance of a rubber product varies depending on the temperature of the road surface that comes into contact with the rubber product, it is necessary to adjust the temperature of the road surface member. For example, Patent Document 1 discloses a friction test device that adjusts the temperature of the road surface member by embedding a heater in the road surface member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-233797 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the temperature of the road surface member is directly adjusted by a heater, as in the friction testing device disclosed in Patent Document 1, it is difficult to adjust the temperature of the road surface member with high precision.

[0005] An object of the present disclosure is to provide a friction testing device and a friction testing method that can accurately adjust the temperature of road surface members. [Means for solving the problem]

[0006] The friction testing device of the present disclosure comprises a road surface member having a test road surface that comes into contact with a test rubber body, a first heat conduction member that comes into direct or indirect contact with the road surface member, a liquid tank that houses the road surface member and the first heat conduction member and stores a liquid, and a liquid temperature adjustment means that can adjust the temperature of the liquid.

[0007] The friction testing method disclosed herein includes a liquid storage step of storing a liquid in a liquid tank that contains a road surface member having a test road surface and a first heat conduction member that comes into direct or indirect contact with the road surface member, a road surface temperature adjustment step of adjusting the temperature of the road surface member via the stored liquid, and a friction testing step of moving a test rubber body relative to the test road surface to perform a friction test on the test rubber body. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of a friction test device. [Figure 2] FIG. 1 is a plan view showing a road surface member, a first heat conduction member, a liquid tank, and a liquid temperature adjustment means. [Figure 3] Cross section of line III-III in Figure 2 [Figure 4] A diagram explaining the movement path of the test rubber body. [Figure 5] Two-sided view of a test rubber body having a preferred shape [Figure 6] A diagram showing an example of the side of the front edge of a test rubber body.

[0009] <Friction test equipment> First, an example of a friction test apparatus 100 will be described with reference to Figures 1 to 6. Note that in each figure, the dimensional ratios in the drawing do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match either. Figure 1 is a diagram schematically showing an example of a friction test apparatus 100.

[0010] As shown in FIG. 1, the friction test apparatus 100 can be used to evaluate the friction performance of rubber products that come into contact with a road surface. Examples of rubber products include tires and shoe soles. The tires may be pneumatic or non-pneumatic. When wet grip tests are performed on an actual vehicle, the test costs are high and the test is easily affected by environmental changes such as weather and season. On the other hand, when a friction test is performed using the friction test apparatus 100, the test costs can be reduced, the test period can be shortened, and the effects of environmental changes such as weather and season can be reduced.

[0011] The friction test device 100 comprises a road surface member 1 having a test road surface 1a that comes into contact with the test rubber body R, a first heat conduction member 11 that comes into direct or indirect contact with the road surface member 1, a liquid tank 2 that houses the road surface member 1 and the first heat conduction member 11 and stores a liquid, and a liquid temperature adjustment means 3 that can adjust the temperature of the liquid. With this configuration, the liquid adjusted by the liquid temperature adjustment means 3 comes into contact with the road surface member 1 via the first heat conduction member 11, making it possible to accurately adjust the temperature of the road surface member 1. Furthermore, because no processing of the road surface member 1 is required to adjust the temperature, for example, there is no risk of damaging the road surface member 1 due to the creation of a hole for burying a heater, etc.

[0012] In this embodiment, the road surface member 1 has a first portion that is in direct contact with the liquid, and a second portion that is in indirect contact with the liquid via a first heat-conducting member 11. The second portion has better heat conduction from (to) the liquid than the first portion. By appropriately providing the first portion and the second portion according to the temperature variation of the road surface member 1, it is possible to suppress the temperature variation of the road surface member 1.

[0013] The test rubber object R may be the rubber product itself, or may be a test rubber piece made from the same rubber material as the rubber product. The test rubber object R is made, for example, from vulcanized rubber and has a flat surface Rf (see FIG. 5) that is pressed against the test road surface 1a. In the example of FIG. 1, the test rubber object R is formed in an inverted truncated cone shape, and its upper surface is adhered to a holder 4 (described later). Therefore, the lower surface of the test rubber object R that faces the test road surface 1a becomes the flat surface Rf that is pressed against the test road surface 1a. The test rubber object R may also be formed in a rectangular parallelepiped or hemispherical shape that has the flat surface Rf. By pressing the test rubber object R against the test road surface 1a, it is also possible to adjust the temperature of the test rubber object R.

[0014] The liquid is a substance with a higher thermal conductivity than air. The liquid is preferably water (for example, tap water or distilled water). This makes it possible to measure the coefficient of friction (wet μ) of the test rubber body R on a wet road surface (described later) and the coefficient of friction (ice μ) on an icy road surface (described later) with a liquid similar to rainwater. Furthermore, by using water as the liquid, it becomes easier to clean the test road surface 1a than when other liquids are used, making it easier to continue using the test road surface 1a. The liquid may be a mixture of water with alcohol or antifreeze, or glycerin. When measuring the wet μ of the test rubber body R, the liquid should have the same kinetic viscosity as water (20 degrees: 1.0034 (mm 2 / s)) is preferred.

[0015] FIG. 2 is a plan view showing the road surface member 1, first heat conduction member 11, liquid tank 2, and liquid temperature adjustment means 3, omitting the test rubber body R and other components. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. As shown in FIGS. 2 and 3, the road surface member 1 is preferably a member cut out from a portion of an actual road surface (asphalt or concrete). For example, the road surface member 1 can be fabricated by joining together (not shown in FIG. 2) multiple cut-out pieces of the actual road surface. Fabricating the road surface member 1 from actual road surface pieces can improve the accuracy of the friction performance evaluation of the test rubber body R (see FIG. 1). Note that the road surface member 1 is not limited to the above, and may also be a member made of aggregates or the like used in actual road surfaces bonded with adhesive, abrasive cloth, anti-slip tape, a flat resin plate, a metal plate, or the like. The test road surface 1a is preferably formed into an uneven shape.

[0016] The test road surface 1a (road surface member 1) is preferably formed in a shape having a longitudinal direction. The longitudinal length of the test road surface 1a is determined, for example, by the maximum moving speed of the test rubber body R. As the moving speed of the test rubber body R increases, the distance required for acceleration and deceleration increases, and therefore the length of the test road surface 1a increases. The length of the test road surface 1a is, for example, 0.5 m or more. In this embodiment, the road surface member 1 is formed in a rectangular shape when viewed from above, but this is not limited to this. For example, the road surface member 1 may be formed in a circular ring shape or the like. The road surface member 1 is formed in a substantially rectangular cross section, and the area of ​​the bottom surface 1f of the road surface member 1 is larger than the areas of the side surfaces 1b and 1c of the road surface member 1.

[0017] It is preferable that a bottom plate 12 (see FIG. 3) be fixed to the bottom surface 1f of the road surface member 1. This prevents the road surface member 1 from collapsing or warping. As a result, the road surface member 1 can be easily transported and replaced.

[0018] The bottom plate 12 is fixed to the bottom surface 1f of the road surface member 1, for example, with an adhesive or the like. The bottom plate 12 is preferably a metal plate. In this embodiment, the bottom plate 12 is a stainless steel plate, but is not limited to this. For example, the bottom plate 12 may be a plate made of the same material as the first heat conduction member 11.

[0019] The width Wd1 of the road surface member 1 (test road surface 1a) is set appropriately depending on the performance of the liquid temperature adjustment means 3 and the number of lanes on which the test rubber body R (see FIG. 5) slides. The width Wd1 is preferably 1.4 times or more the width of the flat surface Rf of the test rubber body R. This ensures that there are lanes for conducting friction tests on the test rubber body R. The width Wd1 is preferably 2 times or less the width of the flat surface Rf of the test rubber body R. This reduces the volume of the road surface member 1 and makes it easier to adjust the temperature of the road surface member 1. In this embodiment, the number of lanes on the test road surface 1a is one. However, this is not limited to the above, and the number of lanes on the test road surface 1a may be two or more. This distributes wear and abrasion per lane due to repeated testing, reducing the frequency of replacing the road surface member 1 due to deterioration.

[0020] First heat conducting member 11 is a member having a higher thermal conductivity than liquid Lq. First heat conducting member 11 is preferably, for example, a metal member. Examples of metals used for the metal member include aluminum (aluminum alloy), stainless steel, steel, and copper. The metal is more preferably aluminum (aluminum alloy), which is corrosion-resistant and has a relatively high thermal conductivity.

[0021] The first heat conducting member 11 is preferably formed in a plate shape, and the main surface of the first heat conducting member 11 is preferably arranged in a position where it comes into contact with the liquid Lq stored in the liquid tank 2. With this configuration, by making the first heat conducting member 11 thin and plate-like (and arranging it, for example, as shown in FIG. 3), heat conduction to (from) the road surface member 1 is improved, and temperature regulation of the road surface member 1 via the first heat conducting member 11 is promoted. The main surface is the surface with the largest area of ​​the first heat conducting member 11. In this embodiment, the first heat conducting member 11 is an aluminum plate, and the main surface is the front surface 11a (or the back surface 11b) of the first heat conducting member 11. The first heat conducting member 11 may be a single plate, or may be made up of multiple plates joined together.

[0022] The thickness of first heat conducting member 11 is preferably 2 mm or more. This improves heat conduction to (from) road surface member 1 in contact with first heat conducting member 11. The thickness of first heat conducting member 11 is preferably 5 mm or less. This prevents the friction testing device 100 from becoming larger due to the provision of first heat conducting member 11. Note that the thickness of first heat conducting member 11 is not limited to the above and may exceed 5 mm. Specifically, first heat conducting member 11 may be formed in a block shape (for example, a rectangular cross section (square cross section, rectangular cross section) or a polygonal cross section).

[0023] It is preferable that the first heat conduction member 11 is arranged in direct or indirect contact with the bottom surface 1f of the road surface member 1. With this configuration, it becomes possible to directly adjust the temperature of the road surface member 1 from the bottom surface 1f of the road surface member 1, where heat is not easily transmitted. This makes it possible to suppress variations in the temperature of the road surface member 1.

[0024] In this embodiment, the first heat conducting member 11 is placed on the bottom surface 2a of the liquid tank 2, and the road surface member 1, to which a bottom plate 12 is fixed, is placed on top of the first heat conducting member 11. That is, the first heat conducting member 11 is indirectly in contact with the road surface member 1 via the bottom plate 12. The road surface member 1 is fixed by a positioning block (not shown) so as not to move in the horizontal direction. In this embodiment, the surfaces 1a to 1e of the road surface member 1 are a first portion that comes into direct contact with the liquid, and the bottom surface 1f of the road surface member 1 is a second portion that comes into indirect contact with the liquid via the first heat conducting member 11.

[0025] The width Wd2 of the first heat conducting member 11 is preferably larger than the width Wd1 of the road surface member 1. The width Wd2 is, for example, substantially the same as the interior width of the liquid tank 2. The length of the first heat conducting member 11 in the longitudinal direction is preferably larger than the length of the road surface member 1 in the longitudinal direction. The length of the first heat conducting member 11 is, for example, substantially the same as the interior length of the liquid tank 2 in the longitudinal direction.

[0026] The liquid tank 2 is formed in the shape of a rectangular parallelepiped with an open top. The road surface member 1 and the first heat conduction member 11 are contained in the liquid tank 2. This allows the liquid Lq and the first heat conduction member 11 (and the road surface member 1) to be in constant contact with each other. As a result, the temperature of the road surface member 1 can be adjusted by heat conduction from (to) the liquid Lq. In this embodiment, the road surface member 1 and the first heat conduction member 11 are all contained in the liquid tank 2, but this is not limited to this. For example, only a portion of the road surface member 1 and the first heat conduction member 11 may be contained in the liquid tank 2.

[0027] It is preferable to provide a gap between each of the side surfaces 1b, 1c of the road surface member 1 and the liquid tank 2. This allows the liquid Lq to be stored between each of the side surfaces 1b, 1c of the road surface member 1 and the liquid tank 2, and by sandwiching the road surface member 1 between the liquid Lq in the short side direction (width direction), temperature regulation of the road surface member 1 is promoted. As a result, temperature variations in the road surface member 1 can be suppressed. It is preferable that the road surface member 1 is housed in the center of the liquid tank 2 in the short side direction.

[0028] The distance Ds1 between the side surface 1b of the road surface member 1 and the side surface 2b of the liquid tank 2 is preferably 50 mm or more. The distance Ds2 between the side surface 1c of the road surface member 1 and the side surface 2c of the liquid tank 2 is preferably 50 mm or more. This makes it possible to provide an agitator (not shown) in the liquid tank 2, which can make the temperature of the liquid Lq more uniform and suppress temperature variations in the road surface member 1. The agitator can be a conventionally known one that is capable of agitating the liquid Lq. The agitator can be one equipped with agitating blades such as propeller blades, paddle blades, or screw blades. The agitator is preferably detachable from the liquid tank 2.

[0029] It is preferable to provide a gap between each of the longitudinal end faces 1d, 1e of the road surface member 1 and the liquid tank 2. This allows the liquid Lq to be stored between the longitudinal end faces 1d, 1e of the road surface member 1 and the liquid tank 2, and by sandwiching the road surface member 1 with the liquid Lq in the longitudinal direction, temperature regulation of the road surface member 1 is promoted. As a result, temperature variations in the road surface member 1 can be suppressed.

[0030] The liquid tank 2 preferably includes a heat insulating layer 21. This reduces the effect of the room temperature in which the friction test device 100 is installed, making it easier to regulate the temperature of the liquid Lq stored in the liquid tank 2 compared to when a liquid tank without a heat insulating layer is used. As a result, it is easier to regulate the temperature of the road surface member 1, and temperature variations in the road surface member 1 can be reduced. In this embodiment, the heat insulating layer 21 is provided in a position that comes into contact with the liquid Lq (inside the liquid tank 2). Specifically, the heat insulating layer 21 forms part of the bottom surface 2a and both side surfaces 2b, 2c of the liquid tank 2. Note that the heat insulating layer 21 is not limited to the above, and may also be provided in a position that does not come into contact with the liquid Lq (outside the liquid tank 2).

[0031] The test road surface 1a of the road surface member 1 contained in the liquid tank 2 is preferably located lower than the upper end of the liquid tank 2 (the rubber body 22 described below). In other words, the depth of the liquid tank 2 is preferably greater than the height of the road surface member 1. This makes it possible to form a film of the liquid Lq on the test road surface 1a by storing the liquid Lq in the liquid tank 2. As a result, by contacting the test road surface 1a with the liquid Lq, it becomes easier to regulate the temperature of the test road surface 1a that is in contact with the test rubber body R of the road surface member 1, and temperature variations in the test road surface 1a can be suppressed. Furthermore, the liquid Lq penetrates into the unevenness formed on the test road surface 1a, and therefore penetrates into the gap between the liquid Lq and the test road surface 1a, making it easier to regulate the temperature of the test road surface 1a. Furthermore, by forming a film of the liquid Lq on the test road surface 1a, it becomes possible to measure the wet μ and ice μ of the test rubber body R. The thickness Th of the liquid Lq film (see FIG. 3) is, for example, 1 mm to 3 mm.

[0032] The liquid tank 2 preferably includes a rubber body 22 to prevent leakage of the liquid Lq. The rubber body 22 is provided on the upper side of the liquid tank 2. The upper surface of the rubber body 22 is provided at a position higher than the test road surface 1a. In this embodiment, the rubber body 22 is formed in a rectangular ring shape, and the rubber body 22 and the insulating layer 21 form both side surfaces 2b, 2c of the liquid tank 2.

[0033] The liquid temperature adjustment means 3 includes a fluid pipe 31 through which a fluid such as a refrigerant flows, and a fluid temperature adjustment device 32 (see FIG. 2) capable of adjusting the temperature of the fluid. The fluid may be, for example, a natural refrigerant such as water or carbon dioxide, or oil. The fluid temperature adjustment device 32 may be, for example, a chiller (cooling water circulation device) or a fluid heating device.

[0034] The fluid pipe 31 is disposed in the liquid tank 2 and submerged in the liquid Lq stored in the liquid tank 2. The fluid pipe 31 is disposed, for example, in a substantially U-shape in the liquid tank 2 and is submerged so as to pass beside both side surfaces 1b, 1c and the end surface 1d of the road surface member 1. The fluid pipe 31 may also be disposed in a substantially I-shape in the liquid tank 2, and the folded portion 311 (see FIG. 2) of the fluid pipe 31 may pass under the road surface member 1.

[0035] The first heat conducting member 11 may be arranged in contact with the fluid pipe 31. With this configuration, heat conduction from (the fluid in) the fluid pipe 31 to the road surface member 1 (from the road surface member 1 to (the fluid in) the fluid pipe 31) via the first heat conducting member 11 is improved, facilitating temperature regulation of the road surface member 1. As a result, it is possible to suppress variations in the temperature of the road surface member 1. Note that the first heat conducting member 11 is not limited to the above, and may not be in contact with the fluid pipe 31.

[0036] In this embodiment, the friction test device 100 includes a second heat conduction member 13, which is arranged in contact with the first heat conduction member 11 and the fluid pipe 31. With this configuration, heat conduction from (the fluid in) the fluid pipe 31 to the road surface member 1 (from the road surface member 1 to (the fluid in) the fluid pipe 31) via the second heat conduction member 13 and the first heat conduction member 11 is improved, facilitating temperature regulation of the road surface member 1. As a result, temperature variations in the road surface member 1 can be suppressed.

[0037] The second heat conducting member 13 may be formed integrally with the first heat conducting member 11, or may be formed separately. When the heat conducting members 11, 13 are formed integrally, no gaps are created between the heat conducting members 11, 13, resulting in good heat conduction in the heat conducting members 11, 13. On the other hand, when the heat conducting members 11, 13 are formed separately, the position of the second heat conducting member 13 can be adjusted. This makes it possible to suppress temperature variations in the road surface member 1 by adjusting the position of the second heat conducting member 13, even if there is a positioning block (not shown) for the road surface member 1 or the fluid pipe 31 and the second heat conducting member 13 cannot be placed between the first heat conducting member 11 and the fluid pipe 31. However, even if the second heat conducting member 13 cannot be placed between the positioning block and the road surface member 1, the second heat conducting member 13 can be placed between the positioning block and the road surface member 1, for example. Furthermore, even if the gap between the first heat conduction member 11 and the fluid pipe 31 is not constant, it is possible to arrange the second heat conduction member 13 with a thickness that varies in accordance with the gap. In this embodiment, the second heat conduction member 13 is separate from the first heat conduction member 11.

[0038] Second heat conducting member 13 is a member having a higher thermal conductivity than liquid Lq. Second heat conducting member 13 is preferably a metal member, for example. Examples of metals used for the metal member include aluminum (aluminum alloy), stainless steel, steel, and copper. The metal is more preferably aluminum (aluminum alloy), which is corrosion-resistant and has a relatively high thermal conductivity. Second heat conducting member 13 is preferably made of the same material as first heat conducting member 11.

[0039] Second heat conducting member 13 is formed, for example, in a block shape. In this embodiment, second heat conducting member 13 is formed to have an L-shaped cross section. This allows two surfaces of second heat conducting member 13 to be in contact with fluid pipe 31. Note that second heat conducting member 13 is not limited to the above, and may be formed, for example, in a rectangular cross section (rectangular cross section, square cross section) or polygonal cross section. Second heat conducting member 13 may also be formed in a plate shape.

[0040] The fluid pipe 31 is preferably positioned lower than the test road surface 1a. With this configuration, when the liquid Lq is stored up to the vicinity of the test road surface 1a, the liquid Lq can be stirred during temperature adjustment, making the temperature of the liquid Lq uniform. This makes it possible to suppress variations in the temperature of the road surface member 1 that comes into direct or indirect contact with the liquid Lq.

[0041] The fluid pipe 31 is preferably disposed on the bottom surface 2a side of the liquid tank 2. This makes it possible to stir the liquid Lq above the liquid tank 2 even if the liquid Lq around the fluid pipe 31 freezes. The liquid Lq may be stirred using the stirrer described above, or may be stirred manually.

[0042] The fluid pipe 31 is preferably positioned at a distance from the road surface member 1. This prevents the liquid Lq that has frozen around the fluid pipe 31 from coming into contact with the road surface member 1. As a result, for example, by stirring the liquid Lq, the temperature of the liquid Lq that comes into contact with the road surface member 1 can be made uniform, thereby suppressing variations in the temperature of the road surface member 1. It is more preferable that the fluid pipe 31 be positioned at a distance of 10 mm or more from the road surface member 1.

[0043] The liquid temperature adjusting means 3 includes a temperature sensor (not shown) that can measure the temperature of the liquid Lq or the test road surface 1 a, and a control unit (not shown) that controls the fluid temperature adjusting device 32 .

[0044] The temperature sensor may be a non-contact sensor (for example, an infrared thermometer) or a contact sensor. In this embodiment, the temperature sensor is a liquid temperature sensor, but is not limited to this. When the temperature sensor is a liquid temperature sensor, it is preferable to measure the liquid temperature on the test road surface 1a with the temperature sensor. This makes it possible to measure a liquid temperature close to the temperature of the test road surface 1a. The position at which the temperature sensor measures the liquid temperature is, for example, the center in the short direction of the test road surface 1a.

[0045] The control unit controls the fluid temperature adjustment device 32 so that the fluid temperature (refrigerant temperature) is maintained at a predetermined temperature. The fluid temperature is determined, for example, by the following equation 1. T2 is the fluid temperature, T1 is the target temperature of the liquid Lq (e.g., the surface of the liquid Lq located above the test road surface 1a), and T0 is the room temperature of the room in which the friction test device 100 is installed. α is a temperature coefficient, which is determined, for example, by the amount of liquid, the surface area of ​​the liquid surface and road surface material 1 in contact with the air, the diameter of the fluid pipe 31 (the surface area in contact with the liquid Lq), the thermal conductivity of each substance, and the insulating properties of the liquid tank 2. Equation 1 can be used when the target temperature T1 is lower than room temperature T0 and the fluid temperature T2 is above 0°C. Equation 1 is preferably used when the temperature difference between the fluid temperature T2 and room temperature T0 is 20°C or less. T2 = T1 + α(T1 - T0) (Equation 1)

[0046] For example, if the target temperature T1 is 15°C, the room temperature T0 is 25°C, and the temperature coefficient α is 0.5, the control unit controls the fluid temperature adjustment device 32 so that the fluid temperature T2 is 10°C. Until the target temperature T1 is reached within ±2°C, the control unit preferably controls the fluid temperature to be lower (for example, 5°C) than the fluid temperature T2 (10°C) calculated by Equation 1. This makes it possible to shorten the time it takes for the temperature of the liquid Lq to reach the target temperature T1.

[0047] The case where the fluid temperature T2 is 0°C or less (where the road surface member 1 is adjusted to a low temperature) will be illustrated. For example, if the target temperature T1 is 5°C and the room temperature T0 is 20°C, the control unit controls the fluid temperature adjustment device 32 so that the fluid temperature T2 is between -10°C and -7°C. The control unit may perform feedback control based on the temperature measured by the temperature sensor.

[0048] The liquid temperature adjusting means 3 may include an input unit (not shown) for inputting the target temperature T1, a display unit (not shown) for displaying the target temperature T1, the fluid temperature T2, and the temperature measured by the temperature sensor, and a calculation unit for calculating the fluid temperature T2. The control unit, input unit, display unit, and calculation unit may be provided in the control device 8 (see FIG. 1 ) described below, or may be provided separately from the control device 8.

[0049] The liquid temperature adjusting means 3 can adjust the temperature of the liquid Lq to, for example, -20°C to 100°C. When measuring wet μ, the liquid temperature adjusting means 3 only needs to adjust the temperature of the liquid Lq to 0°C to 40°C. The temperature of the road surface member 1 can also be adjusted to the same temperature as the liquid Lq. This makes it possible to perform friction tests assuming various environments, such as different seasons and overseas.

[0050] As shown in Figure 1, the friction testing device 100 of this embodiment includes a holder 4 that holds the test rubber body R, a loading device 5 that presses the test rubber body R against the test road surface 1a, a driving device 6 that moves the test rubber body R relative to the test road surface 1a, a load sensor 7 that measures the load acting on the test rubber body R, and a control device 8 that controls the operations required for the test, but is not limited to these.

[0051] The holder 4 is connected to a loading device 5. The loading device 5 is configured to allow the holder 4 to reciprocate in the Z direction (the up-and-down direction in Figure 1) perpendicular to the test road surface 1a. By appropriately setting the position of the holder 4 (the distance between the holder 4 and the test road surface 1a), the load in the Z direction input to the test rubber body R can be adjusted, and ultimately the test rubber body R can be pressed against the test road surface 1a under predetermined pressure conditions. The loading device 5 is configured using a servo motor, but other actuator mechanisms may also be used.

[0052] The driving device 6 is configured to reciprocate a table 9 supporting the load device 5 in the X direction (the left-right direction in FIG. 1). The movement of this table 9 moves the holder 4, which in turn moves the test rubber body R while sliding it on the test road surface 1a. The actuator 10 is configured to reciprocate the table 9 in the Y direction (the direction perpendicular to the paper surface of FIG. 1), which is perpendicular to both the X and Z directions, and is used for aligning the test rubber body R with the test road surface 1a in the Y direction and for changing lanes. In this embodiment, the driving device 6 and the actuator 10 are each configured by a servo motor, but this is not limited to this.

[0053] The load sensor 7 can measure three load components, a vertical component and two horizontal components, and can measure the load in the Z direction (vertical force), the load in the X direction (front-rear force), and the load in the Y direction (lateral force) acting on the test rubber body R. The load sensor 7 is configured by, for example, a load cell. In this embodiment, the load sensor 7 is attached to the upper side of the holder 4 (the side opposite the test rubber body R).

[0054] The control device 8 is equipped with a calculation unit 8a that performs calculations necessary to measure the friction coefficient, an operation control unit 8b that controls the operation of the load device 5, the drive device 6, etc., an input unit 8c that receives input from the test operator, and a display unit 8d that displays on a screen various information related to the operation and settings of the friction test device 100. The measurement value obtained by the load sensor 7 is sent to the control device 8, and the calculation unit 8a calculates the friction coefficient based on the measurement value.

[0055] The friction test apparatus 100 preferably includes a liquid receiving portion (not shown) that receives the liquid Lq that has spilled out of the liquid tank 2. This prevents the liquid Lq from spilling out of the friction test apparatus 100, for example, when the test rubber object R is moved during a friction test on a wet road surface. The liquid receiving portion is provided, for example, on the outside of the liquid tank 2 (particularly, on the side in the direction of movement of the test rubber object R). Note that the liquid Lq may be prevented from spilling out of the liquid tank 2 by increasing the height of the rubber object 22.

[0056] In the friction testing device 100, the flat surface of the test rubber object R is pressed against a test road surface 1a simulating an actual road surface, and the load is measured when the test rubber object R is moved linearly while sliding on the flat test road surface 1a, thereby measuring the coefficient of friction between the test road surface 1a and the test rubber object R. Both the static and kinetic coefficients of friction can be measured. Furthermore, depending on the presence or absence of liquid Lq on the test road surface 1a, the coefficients of friction for dry, wet, and icy roads can also be measured. The pressure conditions for the test rubber object R pressed against the test road surface 1a, as well as the conditions for linear movement, such as speed and path, are controlled by a control device 8. The moving speed can be set so that the test rubber object R slides at a uniform speed over a predetermined section.

[0057] In this way, by pressing the flat surface of the test rubber body R against the flat test road surface 1a, when the test rubber body R is moved linearly while sliding, the change in the contact area is small and stable, and uneven ground contact pressure can be suppressed. Note that this contact area is not the actual contact area with the unevenness of the test road surface 1a, but rather the apparent contact area observed when pressed against a flat plate. Furthermore, in this embodiment, the test rubber body R is moved linearly rather than in a circular motion on the test road surface 1a, so the occurrence of speed differences within the contact area is suppressed. Therefore, this device can accurately measure the coefficient of friction between the test road surface 1a and the test rubber body R.

[0058] The linear movement of the test rubber body R may be any movement of the test rubber body R along the longitudinal direction (X direction) of the test road surface 1a, and examples thereof include the embodiment shown in FIG. 4. In (a), the test rubber body R moves linearly, and its movement path coincides with the longitudinal direction. In (b) and (c), the test rubber body R is vibrated, and in both cases the test rubber body R moves along the longitudinal direction while vibrating in the Y direction. When observed microscopically, (b) is movement along a triangular wave, and (c) is movement along a sine wave, but the center of the amplitude of these vibrations coincides with the longitudinal direction, and such movement is also included in the linear movement.

[0059] In addition to the Y-direction excitation described above, X-direction excitation and Z-direction excitation can also be applied, which are also included in linear movement. When excitation is applied in the X-direction, the motion is a reciprocating motion along the longitudinal direction, and for example, a triangular wave or sine wave excitation is used. When excitation is applied in the Z-direction, the motion is a vertical motion, and for example, a triangular wave, sine wave, pulse wave, or trapezoidal wave excitation is used.

[0060] It is desirable that the contact area of ​​the test rubber body R does not change between stationary and sliding conditions under a specified pressure condition. This pressure condition is approximately 300 to 600 kPa for rubber materials used in passenger car tires, but is higher for truck and bus tires. Furthermore, even if there is a change in the contact area, the area reduction rate is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. To suppress the reduction in the contact area, it is effective to devise the shape of the test rubber body R, as described below.

[0061] The area reduction rate of the test rubber body R is expressed as (S1-S2) / S1, where S1 is the contact area when stationary and S2 is the contact area when sliding. This area reduction rate can be measured, for example, by attaching a transparent glass plate or prism to a sub-section of the test road surface 1a other than the main section required for measuring the friction coefficient (or by replacing the road surface member 1 with a member having a glass plate or prism), and photographing the contact area of ​​the rubber test piece as it passes over it. Alternatively, it can also be measured using a pressure measurement device attached to the main section or sub-section.

[0062] FIG. 5 shows a preferred shape of the test rubber body R. (a) is a front view from the same direction as FIG. 1, with the right side being the front in the sliding direction of the test rubber body R. (b) is a bottom view. The test rubber body R has a flat surface Rf that is pressed against the test road surface 1a. The side surface Rs of the front edge rises from the flat surface Rf. As in this example, it is preferable that the side surface Rs of the front edge and the flat surface Rf form an obtuse angle. This makes it less likely for the front edge to catch on the test road surface 1a when the test rubber body R is slid forward and moved in a straight line, thereby suppressing a decrease in the contact area and uneven ground pressure.

[0063] As described above, the angle θ1 is preferably greater than 90 degrees, which can prevent the leading edge from getting caught. From the viewpoint of enhancing this effect, the angle θ1 is preferably greater than or equal to 100 degrees, and more preferably greater than or equal to 120 degrees. Furthermore, so that the side surface Rs of the leading edge does not come into contact with the test road surface 1a, the angle θ1 is preferably less than or equal to 170 degrees, and more preferably less than or equal to 150 degrees. The shape of the trailing edge is not particularly limited. In FIG. 5, the trailing edge is formed in the same shape as the leading edge, but it may also be formed in a shape perpendicular to the flat surface Rf.

[0064] When measuring the coefficient of friction (wet μ) on a wet road surface, it is preferable that the height h of the side surface Rs of the front edge of the test rubber body R is greater than the thickness Th of the liquid film (see Figure 3). This reduces the resistance of the liquid film under high-speed sliding conditions and improves measurement accuracy.

[0065] When the angle θ1 is an obtuse angle, various shapes can be adopted for the side surface Rs of the front edge, as shown in Figure 6. Of these, in (a) to (c), the side surface Rs is formed by an inclined surface inclined relative to the flat surface Rf. (a) has the same shape as Figure 3, with the side surface Rs inclined downward toward the inside of the test rubber body R. In (d) and (e), the side surface Rs is formed by a curved surface. The side surface Rs of (d) has a rounded chamfered shape, and its radius of curvature is set to, for example, 0.5 to 5 mm. The side surface Rs of (e) has a spoon-shaped chamfered shape, and its radius of curvature is set to, for example, 0.5 to 10 mm.

[0066] <Friction test method> Next, an example of a friction test method will be described with reference to FIGS.

[0067] 2 and 3, first, liquid Lq is stored in a liquid tank 2 (liquid storage step) that contains a road surface member 1 having a test road surface 1a and a first heat conduction member 11 that is in direct or indirect contact with the road surface member 1, and the temperature of the road surface member 1 is adjusted via the stored liquid Lq (road surface temperature adjustment step). In the road surface temperature adjustment step, the temperature of the road surface member 1 that is in contact with the liquid Lq via (and directly from) the first heat conduction member 11 is adjusted by adjusting the temperature of the liquid Lq.

[0068] In the road surface temperature adjustment step, it is preferable to adjust the temperature of the liquid Lq while the liquid Lq is in contact with the main surface of the plate-shaped first heat conduction member 11. In the road surface temperature adjustment step, it is preferable to adjust the temperature of the liquid Lq while the first heat conduction member 11 is in direct or indirect contact with the bottom surface 1f of the road surface member 1.

[0069] In the road surface temperature adjustment process, the temperature of the liquid Lq may be adjusted using a fluid pipe 31 arranged in contact with the first heat conduction member 11, or the temperature of the liquid Lq may be adjusted using a fluid pipe 31 arranged in contact with the first heat conduction member 11 via the second heat conduction member 13.

[0070] The road surface temperature adjustment step preferably includes a liquid agitation step of agitating the liquid Lq. In the liquid agitation step, the liquid Lq may be agitated using the agitator described above, or may be agitated manually. In the liquid agitation step, the liquid Lq is preferably agitated continuously (for example, once every 10 minutes).

[0071] After the temperature of the road surface member 1 reaches near the target temperature (target temperature ±2°C, preferably target temperature ±1°C), the test rubber body R (see FIG. 5) is moved relative to the test road surface 1a to perform a friction test on the test rubber body R (friction test process). Specifically, the flat surface Rf of the test rubber body R is pressed against the test road surface 1a, and the test rubber body R is moved linearly while sliding on the test road surface 1a, and the load is measured to measure the friction coefficient between the test road surface 1a and the test rubber body R. It is preferable not to stir the liquid Lq during the friction test. This is because there is a risk that the liquid Lq will adhere to the test road surface 1a during a friction test on a dry road surface.

[0072] When measuring the coefficient of friction (wet μ) on a wet road surface, a film of liquid Lq is formed on the test road surface 1a, and the flat surface Rf of the test rubber body R is pressed against the test road surface 1a.The load applied when the test rubber body R is slid in a straight line on the wet test road surface 1a is measured, and the coefficient of friction (wet μ) between the wet test road surface 1a and the test rubber body R is measured.

[0073] When measuring the coefficient of friction (iceμ) on a frozen road surface, a film of liquid Lq is formed on the test road surface 1a and then frozen. Then, the flat surface Rf of the test rubber body R is pressed against the frozen test road surface 1a, and the load applied when the test rubber body R is moved in a straight line while sliding is measured, thereby measuring the coefficient of friction (iceμ) between the frozen test road surface 1a and the test rubber body R.

[0074] It is preferable for the operator to supply the liquid Lq to the liquid tank 2 so that the thickness of the liquid Lq film is greater than the film thickness Th during the test (see Figure 3). This is because the liquid Lq may evaporate before the road surface member 1 reaches the target temperature, causing the film thickness to become smaller than the thickness Th. This is also because adjusting the film thickness by reducing the amount of liquid Lq results in smaller changes in the temperature of the road surface member 1 than adjusting the film thickness by adding liquid Lq after the road surface member 1 has reached the target temperature. From the perspective of improving the measurement accuracy of the friction coefficient (wet μ), it is preferable to remove any air bubbles that have formed on the test road surface 1a after the film of liquid Lq has been formed (after supplying liquid Lq to the liquid tank 2) using a brush or the like. This is because surface tension prevents the liquid Lq from penetrating between the irregularities in the test road surface 1a, causing air bubbles to form in those areas.

[0075] After the friction test, the liquid Lq in the liquid tank 2 and rubber residue from the test rubber body R are removed. The liquid Lq is removed from the liquid tank 2, for example, by sucking it out with a vacuum cleaner or by providing a drainage hole in the liquid tank 2. As described above, the liquid Lq is preferably water (tap water, distilled water, etc.) from the viewpoint of making it easy to clean the test road surface 1a.

[0076] (A1) In this embodiment, the first heat conducting member 11 is arranged in indirect contact with the bottom surface 1f of the road surface member 1 via the bottom plate 12, but this is not limited to this. For example, the first heat conducting member 11 may be arranged in direct contact with the bottom surface 1f of the road surface member 1. In other words, the first heat conducting member 11 may be fixed to the bottom surface 1f of the road surface member 1. In this example, the first heat conducting member 11 also functions as the bottom plate 12.

[0077] (A2) For example, the first heat conducting member 11 may be arranged in direct or indirect contact with the side surface 1b (and / or side surface 1c) of the road surface member 1. Also, for example, the first heat conducting member 11 may be arranged in direct or indirect contact with the end surface 1d (and / or end surface 1e) of the road surface member 1.

[0078] (A3) For example, the first heat conduction member 11 may be formed with a substantially U-shaped cross section and may be arranged in direct or indirect contact with both side surfaces 1b, 1c and the bottom surface 1f of the road surface member 1. In this example, both side surfaces 1b, 1c and the bottom surface 1f of the road surface member 1 do not come into direct contact with the liquid Lq.

[0079] (B) In this embodiment, the road surface member 1 is placed on (or fixed to) the bottom surface 2a of the liquid tank 2 via the first heat conduction member 11, but this is not limited to this. For example, the road surface member 1 may be fixed to the side surfaces 2b, 2c of the liquid tank 2.

[0080] (C) In this embodiment, the liquid temperature adjustment means 3 includes a liquid-cooled fluid temperature adjustment device 32, but is not limited to this. For example, the liquid temperature adjustment means 3 may include an air-cooled liquid temperature adjustment device that can adjust the temperature of the liquid Lq using a fan or the like. The liquid temperature adjustment means 3 may also include a water heater or the like that heats the liquid Lq.

[0081] (D) In ​​this embodiment, the liquid temperature adjusting means 3 adjusts the temperature of the liquid Lq stored in the liquid tank 2, but this is not limited to this. For example, the liquid temperature adjusting means 3 may adjust the temperature of the liquid Lq before it is stored in the liquid tank 2. Specifically, the friction testing apparatus 100 may include a supply means that supplies the liquid Lq to the liquid tank 2, and the liquid temperature adjusting means 3 may adjust the temperature of the liquid Lq supplied by the supply means.

[0082] (E) The friction test apparatus 100 according to the present embodiment measures the load when the test rubber object R is caused to move linearly while sliding, but is not limited to this. For example, the friction test apparatus 100 may measure the load when the test rubber object R is caused to move linearly while rolling. Furthermore, the friction test apparatus 100 may measure the load when the test rubber object R is caused to move in a rotational manner.

[0083] (F) The friction test device 100 may be equipped with an ambient temperature control device (for example, a thermostatic bath or thermostatic room) that can control the ambient temperature. This makes it easier to control the temperature of the road surface member 1, and further reduces variations in the temperature of the road surface member 1.

[0084] It will be understood by those skilled in the art that the above-described embodiments are examples of the following aspects.

[0085] [1] As described above, the friction testing device according to this embodiment comprises a road surface member having a test road surface that comes into contact with the test rubber body, a first heat conduction member that comes into direct or indirect contact with the road surface member, a liquid tank that houses the road surface member and the first heat conduction member and stores a liquid, and a liquid temperature adjustment means that can adjust the temperature of the liquid.

[0086] According to this configuration, the liquid regulated by the liquid temperature regulating means comes into contact with the road surface member via the first heat conducting member, thereby making it possible to regulate the temperature of the road surface member with high precision.

[0087] [2] Furthermore, in the friction testing device described in [1] above, it is preferable that the first heat conduction member is formed in a plate shape, and the main surface (surface) of the first heat conduction member is positioned in a position where it comes into contact with the liquid stored in the liquid tank.

[0088] According to this configuration, by making the first heat conducting member thin and plate-like, heat conduction to (from) the road surface member is improved, and temperature regulation of the road surface member via the first heat conducting member is promoted.

[0089] [3] In addition, in the friction testing device described in the above [1] or [2], it is preferable that the first heat conduction member is arranged in direct or indirect contact with the bottom surface of the road surface member.

[0090] With this configuration, it is possible to directly adjust the temperature of the road surface member from the bottom surface of the road surface member, where heat is not easily transmitted, thereby suppressing variations in the temperature of the road surface member 1.

[0091] [4] Furthermore, in the friction testing device described in any one of [1] to [3] above, the liquid temperature adjusting means may include a fluid pipe disposed in the liquid tank, and the first heat conducting member may be disposed in contact with the fluid pipe.

[0092] With this configuration, heat conduction from the fluid pipe (fluid therein) to the road surface member (from the road surface member to the fluid pipe (fluid therein)) via the first heat conduction member is improved, facilitating temperature regulation of the road surface member.

[0093] [5] Furthermore, the friction testing device described in any one of [1] to [3] above may be configured to include a second heat conducting member, the liquid temperature adjusting means includes a fluid pipe disposed in the liquid tank, and the second heat conducting member is disposed in contact with the first heat conducting member and the fluid pipe.

[0094] With this configuration, heat conduction from the fluid pipe (fluid in the fluid pipe) to the road surface member (from the road surface member to the fluid pipe (fluid in the fluid pipe)) via the second heat conduction member and the first heat conduction member is improved, facilitating temperature regulation of the road surface member.

[0095] [6] In addition, in the friction testing device described in any one of [1] to [5] above, it is preferable that the liquid temperature adjustment means includes a fluid pipe arranged in the liquid tank, and the fluid pipe is arranged at a position lower than the test road surface.

[0096] With this configuration, when the liquid is stored close to the test road surface, the liquid can be stirred during temperature adjustment to make the liquid temperature uniform, thereby suppressing temperature variations in road surface members that come into direct or indirect contact with the liquid.

[0097] [7] The friction testing method according to this embodiment includes a liquid storage step of storing a liquid in a liquid tank containing a road surface member having a test road surface and a first heat conduction member that is in direct or indirect contact with the road surface member, a road surface temperature adjustment step of adjusting the temperature of the road surface member via the stored liquid, and a friction testing step of moving a test rubber body relative to the test road surface to perform a friction test on the test rubber body.

[0098] According to this method, the liquid regulated in the road surface temperature regulation step comes into contact with the road surface member via the first heat conduction member, thereby enabling the temperature of the road surface member to be regulated with high precision.

[0099] [8] In addition, in the friction test method described in [7] above, it is preferable that in the road surface temperature adjustment process, the temperature of the liquid is adjusted while the main surface of the first heat conduction member formed in a plate shape is in contact with the liquid.

[0100] According to this method, by making the first heat conducting member thin and plate-like, heat conduction to (from) the road surface member is improved, and temperature regulation of the road surface member via the first heat conducting member is promoted.

[0101] [9] Furthermore, in the friction test method described in [7] or [8] above, it is preferable that in the road surface temperature adjustment process, the temperature of the liquid is adjusted while the first heat conduction member is in direct or indirect contact with the bottom surface of the road surface member.

[0102] This method makes it possible to directly adjust the temperature of the road surface member from the bottom surface of the road surface member, where heat is not easily transmitted, thereby suppressing variations in the temperature of the road surface member.

[0103]

[10] Furthermore, in the friction test method described in any one of [7] to [9] above, the road surface temperature adjustment step may be a method in which the temperature of the liquid is adjusted using a fluid pipe arranged in contact with the first heat conduction member.

[0104] According to this method, heat conduction from the fluid pipe (fluid therein) to the road surface member 1 (from the road surface member to the fluid pipe (fluid therein)) via the first heat conduction member is improved, facilitating temperature regulation of the road surface member.

[0105]

[11] Furthermore, in the friction test method described in any one of [7] to [9] above, the road surface temperature adjustment step may be a method in which the temperature of the liquid is adjusted using a fluid pipe arranged in contact with the first heat conduction member via the second heat conduction member.

[0106] According to this method, heat conduction from the fluid pipe (fluid in the fluid pipe) to the road surface member (from the road surface member to the fluid pipe (fluid in the fluid pipe)) via the second heat conduction member and the first heat conduction member is improved, thereby facilitating temperature regulation of the road surface member.

[0107]

[12] In addition, in the friction test method described in any one of the above [7] to

[11] , the road surface temperature adjustment step preferably includes a liquid stirring step of stirring a liquid.

[0108] According to this method, the temperature of the liquid can be made uniform, and variations in the temperature of the road surface members that come into direct or indirect contact with the liquid can be suppressed.

[0109] The friction test apparatus and the friction test method are not limited to the configurations of the above-described embodiments, and are not limited to the above-described effects. Furthermore, it goes without saying that various modifications can be made to the friction test apparatus and the friction test method without departing from the spirit and scope of the present invention. For example, it goes without saying that one or more of the configurations and methods according to the above-described various modified examples can be arbitrarily selected and adopted in the configurations and methods according to the above-described embodiments. [Explanation of symbols]

[0110] 100... friction test apparatus, 1... road surface member, 1a... test road surface, 2... liquid tank, 21... heat insulating layer, 22... rubber body, 3... liquid temperature adjustment means, 31... fluid pipe, 32... fluid temperature adjustment device, 4... holder, 5... load device, 6... drive device, 7... load sensor, 8... control device, 8a... calculation unit, 8b... operation control unit, 8c... input unit, 8d... display unit, 9... table, 10... actuator, 11... first heat conduction member, 12... bottom plate, 13... second heat conduction member, R... test rubber body, Rf... flat surface, Rs... side surface, Lq... liquid

Claims

1. a road surface member having a test road surface that comes into contact with the test rubber body; a first heat conduction member that is in direct or indirect contact with the road surface member; a liquid tank that accommodates the road surface member and the first heat conduction member and stores liquid; and a liquid temperature adjusting means capable of adjusting the temperature of the liquid.

2. The first heat conducting member is formed in a plate shape, The friction testing device according to claim 1 , wherein a main surface of the first heat conducting member is disposed at a position where it comes into contact with the liquid stored in the liquid tank.

3. The friction testing device according to claim 1 , wherein the first heat conducting member is disposed in direct or indirect contact with the bottom surface of the road surface member.

4. the liquid temperature adjusting means includes a fluid pipe disposed in the liquid tank; The friction testing device of claim 1 , wherein the first heat conducting member is disposed in contact with the fluid pipe.

5. a second heat conducting member; the liquid temperature adjusting means includes a fluid pipe disposed in the liquid tank; 2. The friction testing device of claim 1, wherein the second heat conducting member is disposed in contact with the first heat conducting member and the fluid pipe.

6. the liquid temperature adjusting means includes a fluid pipe disposed in the liquid tank; 6. The friction testing device according to claim 1, wherein the fluid pipe is disposed at a position lower than the test road surface.

7. a liquid storing step of storing a liquid in a liquid tank that contains a road surface member having a test road surface and a first heat conduction member that is in direct or indirect contact with the road surface member; a road surface temperature adjusting step of adjusting the temperature of the road surface member via the stored liquid; a friction testing step of moving the test rubber body relative to the test road surface to conduct a friction test on the test rubber body.

8. 8. The friction testing method according to claim 7, wherein the road surface temperature adjusting step adjusts the temperature of the liquid while the liquid is in contact with a main surface of the first heat conduction member formed in a plate shape.

9. 8. The friction testing method according to claim 7, wherein in the road surface temperature adjusting step, the temperature of the liquid is adjusted with the first heat conduction member in direct or indirect contact with the bottom surface of the road surface member.

10. 8. The friction testing method according to claim 7, wherein the road surface temperature adjusting step adjusts the temperature of the liquid using a fluid pipe arranged in contact with the first heat conducting member.

11. 8. The friction testing method according to claim 7, wherein the road surface temperature adjusting step adjusts the temperature of the liquid using a fluid pipe arranged in contact with the first heat conducting member via a second heat conducting member.

12. The friction testing method according to any one of claims 7 to 11, wherein the road surface temperature adjustment step includes a liquid agitation step of agitating the liquid.

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