JP6270503B2 - Method for forming snow road of tire test drum - Google Patents

Description

  The present invention relates to a method for forming a snow road of a tire test drum, a tire testing apparatus, and a method for evaluating the performance of a tire on snow. More particularly, the present invention relates to a method for forming a snow road on the inner peripheral surface of a tire test driving drum, a tire testing apparatus, and a method for evaluating the performance of a tire on snow.

  Conventionally, a test for evaluating the performance of a tire when running on snow has been performed by an actual vehicle. However, this actual vehicle running test can only be conducted during the snowfall season. Furthermore, it is almost impossible to control test conditions such as temperature, humidity, and snow quality. In place of the actual vehicle running test including such problems, a table running test using a test apparatus is often performed for evaluating the performance of the tire on the snow.

  As this tabletop running test, a test disclosed in Japanese Patent Application Laid-Open No. 2008-14667 is known. For this test, a test apparatus having a cylindrical drive drum is used. The drive drum is rotatable about a shaft disposed in the horizontal direction. Artificial snow is blown by the snow gun over the entire circumference of the inner peripheral surface of the drive drum. Artificial snow adheres directly to the inner peripheral surface of the drive drum. This artificial snow is pressed against the inner peripheral surface of the drive drum by a pressure snow roller. Thereby, a snow road surface is formed over the entire circumference of the inner peripheral surface.

  The test tire is rotated by the drive drum while being pressed against the snow road surface on the inner periphery of the drive drum with a predetermined test load. The test tire is rotated over the entire circumference of the drive drum by the drive drum at a speed equivalent to that of the actual vehicle. This test apparatus is also called an inside drum type test apparatus. The test tire is braked or accelerated by applying a braking force or a driving force separately from the drum. Various loads generated on the rotating test tire are measured. Based on the measurement data and the secondary data calculated from the measurement data, the performance on the snow of the tire is evaluated.

  The test apparatus requires a snow gun or the like to form a snow road. The test equipment is large and complex. Further, since artificial snow is directly attached to the inner peripheral surface of the drive drum, the state differs from an actual snow road having an ice layer. That is, since the friction coefficient between the road surface under snow and the snow is different, there is a possibility that the behavior of the tire during running on the actual road may not be reproduced.

JP 2008-14667 A

  The present invention has been made in view of the current situation, and provides a method for forming a snow road in a state close to an actual snow road easily and quickly with respect to the inner peripheral surface of the drive drum. An object of the present invention is to provide a test apparatus having a drive drum in which a snow road is formed by the method, and to provide a method for evaluating the performance of a tire on snow using the test apparatus.

The method for forming a snow road of the tire test drum according to the present invention is as follows.
An ice plate forming step for forming an ice plate on the inner peripheral surface of the drum for driving the tire;
A rotation step for rotating the drum at a constant speed;
An insertion step of biting a cutting tool from the surface of the ice plate outward in the radial direction of the drum;
A lateral movement step of moving the bite at a constant speed in the width direction of the rotating drum,
Repeat steps to repeat the insertion step and the lateral movement step in that order when necessary,
And a snow road surface forming step of laying snow generated by this repeating step on the inner surface of the drum.

  Preferably, the rotational speed Vd of the drum is 3 m / s or more and 12 m / s or less.

  Preferably, the speed Vv of the horizontal movement of the cutting tool is 5 mm / s or more and 40 mm / s or less.

Preferably, a ratio Vv / Vd of a lateral movement speed Vv of the bit with respect to a rotational speed Vd of the drum is 3.33 × 10 ⁻³ or less.

  Preferably, the bite penetrates into the ice plate at a depth of 0.5 mm or more and 2.0 mm or less.

A test apparatus according to the present invention is a test apparatus for running a tire on snow,
A drum with a snow path formed on the inner surface,
A drum support device for rotatably supporting the drum;
A tire support device that rotatably supports the test tire and that can be pressed against the surface of the snow road;
A tire driving device that rotationally drives the test tire,
The snow road is formed on the inner peripheral surface of the drum by any one of the methods described above.

An evaluation method for performance on snow of a tire according to the present invention is an evaluation method using a test apparatus,
This test apparatus is the test apparatus described above,
A rotation driving step for rotating the test tire in a state where the outer peripheral surface of the test tire is pressed on the snow road on the inner peripheral surface of the drive drum;
During this rotational drive step, a measurement step for measuring the longitudinal force applied to the test tire from the inner peripheral surface,
And an evaluation step for evaluating the performance on the snow of the test tire based on the measured longitudinal force.

  Preferably, in the evaluation step, the maximum value of the longitudinal force measured during a predetermined travel time is employed.

  According to the method for forming a snow road for a tire test drum according to the present invention, a snow road in a state close to an actual snow road can be easily and quickly formed on the inner peripheral surface of the drum. According to the method for evaluating on-snow performance of a tire according to the present invention, a correlation with the state of an actual vehicle during acceleration on snow is recognized, and more effective on-snow performance can be evaluated.

FIG. 1 is a partial cross-sectional front view schematically showing an example of a test apparatus used for executing a method for evaluating the performance on snow of a tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the driving drum in the test apparatus of FIG. 1 along the II-II line direction. 3 is a partial cross-sectional front view illustrating a method of forming a snow road on the inner peripheral surface of the test apparatus of FIG. 4 (a) and 4 (b) are side views showing the state of snow on the inner peripheral surface of the drive drum of FIG. FIG. 5A is a graph showing the rotational speed of the tire measured over time, and FIG. 5B is a graph showing the longitudinal force of the tire measured over time. FIG. 6 is a graph showing a relationship between an index of tire longitudinal force measured in a tire running test using a test apparatus and an index of start acceleration time on snow measured in an actual vehicle running test.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

[Test equipment]
FIG. 1 shows a test apparatus 1 used for execution of a method for evaluating the performance of a tire on snow according to this embodiment. The test apparatus 1 is placed in a low temperature environment below freezing point. The test apparatus 1 includes a test rim (not shown) on which a test tire (hereinafter also simply referred to as a tire) T is mounted, a tire support device 3 that holds the rim at the tip, and a test tire T that is driven to rotate. A possible drive drum 4 is provided. The drive drum 4 is rotatably supported by the drum support device 5. The drum support device 5 includes a drive device 6 including an electric motor for rotating the drive drum 4. The drive device 6 can control the rotation speed.

  As is apparent from FIG. 2 as well, the drive drum 4 has a bottomed cylindrical shape. A rotating shaft 8 of the drum support device 5 is connected to the bottom plate 7 of the driving drum 4. The rotating shaft 8 is supported by the bearing 9 and is connected to the output shaft of the driving device 6. The test tire T mounted on the rim is inserted into the drive drum 4 from the opening 10 side of the drive drum 4. A ring-shaped flange 15 is formed along the periphery of the drive drum 4 on the opening 10 side. On the inner peripheral surface of the drive drum 4, an ice layer (hereinafter referred to as “ice board”) 16 having a constant thickness is formed. A snow path 17 is formed in a predetermined range on the surface of the ice plate 16. The test tire T is pressed against the inner peripheral surface of the drive drum 4 from above the snow road 17.

  The rim is supported by the rotating shaft 11 of the tire support device 3. The tire support device 3 includes a drive device 12 that includes an electric motor or the like for driving the rotary shaft 11 to rotate. The drive device 12 can control the rotation speed. With this driving device 12, the sample tire T can rotate without depending on the driving drum 4. The tire support device 3 also has a braking function for making the rotating shaft 11 a free rotating state, accelerating or decelerating the rotation of the rotating shaft 11, or stopping the rotating shaft 11. Both the tire support device 3 and the drum support device 5 are installed on the test rack 1a.

  The tire support device 3 includes a lifting device 13. By this elevating device 13, the rim on which the test tire T is mounted is moved up and down. By this lifting device 13, the test tire T is moved closer to the surface of the snow road 17 of the drive drum 4. The elevating device 13 can press the test tire T against the surface of the snow road 17 with an arbitrary load. If the test tire T is pressed against the surface of the snow road 17 in a rotatable state (free rolling) and the drive drum 4 rotates, the test tire T rotates. When the test tire T is pressed against the surface of the snow road 17 and rotated while the drive drum 4 is rotatable, the drive drum 4 also rotates.

  A load cell 14 is attached to a portion where the rotating shaft 11 is supported. The load cell 14 has a reaction force (also referred to as a load) Fz applied perpendicularly (in the radial direction of the drive drum) from the drive drum 4 to the test tire T, and a force in the tangential direction of the drive drum 4 and the test tire T ( It is attached in a direction in which Fx can be measured. As this load cell 14, a 6 component force load cell may be used. It is also easy to measure the lateral force Fy of the test tire T.

[Formation of snowy road]
Hereinafter, a method for forming the snow path 17 on the drive drum 4 will be described with reference to FIGS. 3 and 4. The ice plate 16 is formed by supplying water to the inner peripheral surface of the driving drum 4 while rotating the drive drum 4 in an atmosphere below freezing point. The thickness of the ice plate 16 is preferably in the range of about 10 mm to 100 mm. This is because if the ice plate 16 is too thin, the ice plate 16 may be broken during cutting or testing, and the tire T and the surface of the drive drum 4 may come into contact with each other. Next, the surface of the ice plate 16 is smoothly cut by a cutting bit (hereinafter also simply referred to as a bit) 21. The surface (inner peripheral surface) of the scraped ice disk 16 is substantially coaxial with the inner peripheral surface of the drive drum 4. Powdered ice generated by cutting the ice plate 16 becomes snow 18 for forming a snow path 17 on the surface of the ice plate 16. Hereinafter, a specific method for forming the snow path 17 on the inner peripheral surface of the ice plate 16 will be described.

  The drive drum 4 on which the ice plate 16 is formed is rotated at a predetermined constant speed Vd. The cutting tool 21 is positioned on one end side in the width direction of the drive drum 4. This one end side is the opening 10 side end portion in the present embodiment, but is not limited to this. The cutting tool 21 may be positioned at the end of the drive drum 4 on the bottom plate 7 side. At this position, the cutting tool 21 is displaced radially outward of the drive drum 4 and stopped at a position where it abuts on the surface of the ice plate 16. Further, the cutting tool 21 is displaced by a predetermined distance D outward in the radial direction of the drive drum 4, and is bitten by a depth D from the surface of the ice plate 16. In this state, the cutting tool 21 is reciprocated (laterally moved) in the axial direction (width direction) of the drive drum 4 at a predetermined constant speed Vv. When the bite 21 returns to its original position even if it is reciprocated once in the width direction, the bite 21 is bitten again by a predetermined depth D from the new surface of the ice plate 16. The cutting tool 21 is further reciprocated. The bite 21 bites into the ice plate 16 at a predetermined depth D and repeats a reciprocating motion in the width direction at a constant speed Vv in that order as necessary. A constant amount of snow 18 can be generated by the rotation of the drive drum 4 at a constant speed Vd and the reciprocating motion of the cutting tool 21 at a constant speed Vv. If the necessary amount of snow 18 is generated by one reciprocating motion, the reciprocating motion does not need to be repeated.

  The bite depth D for each reciprocating motion of the cutting tool 21 is preferably 0.5 mm or more and 2.0 mm or less. If the bite depth D is less than 0.5 mm, it takes too much time to generate the snow 18. When the biting depth D exceeds 2.0 mm, the bit 21 is excessively loaded from the ice plate 16, and the bit 21 may be damaged. Furthermore, there is a risk that a large hole or crack will occur in the ice plate 16. When the ice plate 16 is shaved by a predetermined amount (FIG. 4A), this ice cutting process is completed.

  The rotational speed Vd of the drive drum 4 is preferably 3 m / s or more and 12 m / s or less. If the rotational speed Vd is less than 3 m / s, it may take too much time to generate the snow 18. On the other hand, when the rotational speed Vd exceeds 12 m / s, the generated snow 18 may be scattered and it may be difficult to obtain a necessary amount of snow 18.

  The width W dimension (FIG. 3) of the cutting tool 21 is not particularly limited, but is set to 35 mm in this embodiment. The lateral movement speed Vv of the cutting tool 21 is preferably 5 mm / s or more. If the lateral movement speed Vv is less than 5 mm / s, it may take too much time to generate the snow 18.

The ratio Vv / Vd of the lateral movement speed Vv of the cutting tool 21 to the rotational speed Vd of the drive drum 4 is preferably 3.33 × 10 ⁻³ or less. That is, it is preferable that Vv / Vd ≦ 3.33 × 10 ⁻³ . If the speed Vv of the lateral movement of the cutting tool 21 exceeds 3.33 × 10 ⁻³ times the rotational speed Vd of the driving drum 4, the cutting tool 21 may be overloaded and the cutting tool 21 may be damaged.

Here, as described above, the rotational speed Vd of the drive drum 4 is preferably 12 m / s or less. Therefore, when this is applied to the relationship Vv / Vd ≦ 3.33 × 10 ⁻³ , the lateral movement speed Vv of the cutting tool 21 is 12 m / s × (3.33 × 10 ⁻³ ) = 40 mm / s or less. Is preferred. That is, the lateral movement speed Vv of the cutting tool 21 is preferably 5 mm / s or more and 40 mm / s or less.

  In the present embodiment, the cutting tool 21 is bitten into the ice plate 16 every round trip in the width direction. However, it is not limited to such a configuration. The bite 21 bites in each way, or every 1.5 round trips or more. In these cases, the preferable ranges of the rotational speed Vd of the drive drum 4 and the lateral movement speed Vv of the cutting tool can be appropriately changed. Further, the cutting tool 21 may be bitten into the ice plate 16 only at one time of forward movement and backward movement, and may be retracted upward at the other time.

  The atmospheric temperature of the test apparatus 1 affects the properties of the snow 18 formed by cutting the ice plate 16. According to the investigation, the relationship between the ambient temperature of the test apparatus 1 and the snow quality formed is almost as follows. When the ambient temperature is in the range of 0 ° C. to −2 ° C., sherbet-like snow (also called snow quality S) 18 is obtained. When the ambient temperature is in the range of −3 ° C. to −6 ° C., it becomes moist and powdery snow containing water (referred to as snow quality A) 18. When the atmospheric temperature is −7 ° C. or lower, the powdery snow (referred to as snow quality B) 18 with little moisture is obtained. When the atmospheric temperature is in the range of −2 ° C. to −3 ° C., the snow quality S and the snow quality A are mixed. When the ambient temperature is in the range of −6 ° C. to −7 ° C., snow quality A and snow quality B are mixed. The temperature in the test chamber in which the test apparatus 1 is installed is set according to the quality of snow to be manufactured. Snow quality can be controlled by controlling the test room temperature.

  As described above, the snow 18 generated by cutting is spread on a part of the surface (inner peripheral surface) of the ice plate 16. Thereby, the snow path 17 is formed in a part of inner peripheral surface of the ice board 16 (FIG.4 (b)). Thus, the snow road 17 close to the actual snow road surface in which an ice layer exists between the snow and the road surface is formed. Hereinafter, the inner peripheral surface of the ice disk 16 may also be referred to as the inner peripheral surface of the drive drum 4. This snow 18 is spread with a certain thickness using a broom or the like. The laying range of the snow 18 is preferably the entire inner circumferential surface of the drive drum 4 in the width direction, 50 cm or more in the circumferential direction, and ¼ or less of the circumferential length. As will be described later, in the evaluation test of the on-snow performance of the tire T, the test tire T is usually rotated at a low speed while the drive drum 4 is stationary. Travel time is short. Therefore, it can be said that the snow road 17 is sufficient in the above-mentioned 1/4 range. On the other hand, if the snow road 17 is formed in a range exceeding ¼, the upper part of the snow road 17 may collapse, so it is preferable to avoid it. As described above, by installing the cutting tool 21, a new snow road surface can be formed easily and quickly without using a special snowfall device. This is clear from the examples described later.

[Evaluation of tire performance on snow]
The table running test using the test apparatus 1 will be described below. The test apparatus 1 can be used to evaluate the on-snow performance of the tire T, specifically, the front-rear grip performance (vertical grip performance). Furthermore, it is possible to confirm the validity of the evaluation of the performance on the snow of the tire T using the test apparatus 1 by an actual vehicle running test. In other words, by comparing the evaluation of the vertical grip performance by the table running test with the evaluation of the vertical grip performance by the actual vehicle driving, and confirming the correlation between the two evaluations, the validity of the table driving test result can be confirmed. . This point will be described later. As the test tire T, a plurality of types of tires having different tire patterns are prepared. The test tire T is attached to the support device 3 of the test apparatus 1 after being mounted on a test rim. The test tire T is filled with air so as to have a predetermined internal pressure (test internal pressure). The drive drum 4 is brought into a rotation stop state or rotated at a predetermined test rotation speed.

  The test tire T is pressed against the snow road 17 of the drive drum 4 in a state where the rotation is stopped. Next, the test tire T starts to rotate (run). When the drive drum 4 is rotating, the test tire T starts to rotate in the same direction as the rotation direction of the drive drum 4. While the test tire T is running, it is possible to measure the longitudinal force Fx, the lateral force Fy, the vertical load Fz to the snowy road 17, the rotational speed of the drive drum 4 and the test tire T while the test tire T is running. is there. In this embodiment, the vertical grip performance on the snow of the test tire T, in particular, the start acceleration performance is evaluated by the measured longitudinal force Fx. The on-snow braking performance of the test tire T is evaluated based on the longitudinal force Fx during braking of the test tire T. That is, the drive drum 4 and the sample tire T are rotated in the same direction, and the rotation of the sample tire T is stopped. The braking performance on snow of the test tire T is evaluated by the longitudinal force Fx measured at this time.

  The test tire T can be in a free rolling state without being driven to rotate, and can be driven to rotate by the drive drum 4. When the cornering performance of the test tire T is evaluated after setting the slip angle and the camber angle on the test tire T, the test tire T may be in a free rolling state. Further, as will be described later, when observing the pattern transferred onto the snow road surface by running of the test tire T, the test tire T is brought into a free rolling state.

  Hereinafter, an evaluation test of the start acceleration performance of the test tire T will be described. The rotational speed Vd of the drive drum 4 is preferably 0 m / s or more and 0.80 m / s or less. When the drum rotation speed Vd exceeds 0.80 m / s, the travel distance of the test tire T immediately exceeds the range of the snow road 17 that is the inner circumference ¼ of the drive drum 4. In this case, it may be difficult to evaluate the start acceleration performance. In the present embodiment, the drive drum 4 is stopped in a free rolling state.

  As shown in FIG. 5A, the test tire T starts running after being pressed against the snow road 17 in a non-rotating state. When a predetermined test speed is reached, that speed is maintained. The running of the test tire T is continued for a predetermined time. The rotational speed of the test tire T is continuously measured and recorded over time. In FIG. 5A, the horizontal axis represents the elapsed time, and the vertical axis represents the rotational speed of the test tire T. The running speed of the test tire T is low and the running time is short. This is because if the traveling speed is high and the traveling time is long, the traveling distance of the test tire T immediately exceeds the range of the snow road 17 that is the inner circumference ¼ of the drive drum 4. As shown in FIG. 5B, the longitudinal force Fx during the running of the test tire T is continuously measured and recorded over time by the load cell 14 described above. In FIG. 5B, the horizontal axis indicates the elapsed time, and the vertical axis indicates the longitudinal force Fx of the test tire T.

  From the longitudinal force Fx shown in FIG. 5B, the performance on the snow of the test tire T can be evaluated. It can be determined that the greater the longitudinal force Fx, the more firmly the tire T is gripping the snow road surface. It can be evaluated that the longer the longitudinal force Fx is, the higher the vertical grip performance on the snow of the test tire T, that is, the start acceleration performance.

[Correlation evaluation between bench driving test and actual vehicle driving test]
In the table running test and the actual vehicle running test, four types of test tires T, which are different patterns 1, 2, 3, and 4, were prepared. Each of the test tires T has a size of 195 / 65R15, a rim width of 6.5 J, and an internal pressure of 230 kPa.

  The driving drum 4 of the test apparatus 1 has an inner diameter of about 3 m, a width of about 1 m, a thickness of the ice plate 16 of about 5 cm, and a thickness of the snow path 17 on the ice plate 16 of about 5 cm. The snow road 17 was spread in the lower part of the inner peripheral surface of the drive drum 4 in a range of 1/4 (about 2.36 m) of the circumferential length. The drive drum is stationary. The test tire T was pressed against the surface of the snow path 17 of the stationary drive drum 4 by a load of 4.24 kN in a non-rotating state. The test tire T was rotated from this stationary state at a speed of 0.97 m / s. The rotation duration is 8 seconds. The longitudinal force Fx of the test tire T during running was measured. For the evaluation of the start acceleration performance, the highest measured value of the longitudinal force Fx from the start of travel of the test tire T to the end of travel was adopted.

  As shown in Table 1, an index of 100 was given as a reference value for the longitudinal force Fx of the test tire T of Pattern 1. The longitudinal force Fx of each test tire T of the other patterns 2, 3 and 4 is indicated by an index. It can be evaluated that the start acceleration performance on the snow of the test tire T is higher as the index is larger.

  On the other hand, the actual vehicle running test was conducted as follows. The test vehicle is a domestically produced front-wheel drive four-wheel vehicle, and the engine displacement is 1800 cc. The test tires T to be mounted on the test vehicle are four types of tires having the same specifications as those used in the above-described bench driving test. The same pattern of tires was mounted on all four wheels of the test vehicle. The rim width is 6.5 J and the internal pressure is 230 kPa.

  The test was conducted on a test course in which fresh snow having a thickness in the range of 2 cm to 4 cm was piled on a flat compressed snow. The weather was clear or cloudy. The temperature ranged from -4 ° C to -6 ° C, and the snow temperature ranged from -5 ° C to -6 ° C. The test vehicle started and accelerated the test course at a vehicle speed of 5 km / h. The travel time (also called start acceleration time) until the travel distance reached 50 m was measured. It can be evaluated that the start acceleration performance on the snow of the test tire T is higher as the traveling time is shorter.

  As shown in Table 1, an index of 100 was given as a reference value for the running time for the test tire T of pattern 1. The running times of the test tires T of the other patterns 2, 3 and 4 are indicated by indices. It can be evaluated that the start acceleration performance on the snow of the test tire T is higher as the index is smaller.

  In FIG. 6 and Table 1, for the test tires T of patterns 1, 2, 3, and 4, the index of the longitudinal force Fx in the table running test (pattern 1 is set to 100) and the running time in the actual vehicle running test The index is contrasted. In FIG. 6, the horizontal axis indicates the index of the longitudinal force Fx of each tire T, and the vertical axis indicates the index of the start acceleration time of the actual vehicle equipped with each tire T. As a result of both tests, it can be evaluated that the start acceleration performance on snow is high in the order of pattern 4, pattern 3, pattern 2, and pattern 1. Correlation between the bench driving test and the actual vehicle driving test is confirmed.

  In order to evaluate the ability of the tire pattern to grip the snow road surface, it is also possible to observe the tire pattern (hereinafter also referred to as a transfer pattern) transferred on the snow road surface after the tire has traveled on the snow road surface. Useful. In this case, since the generated force such as the longitudinal force is not measured, the sample tire T is in a free rolling state when the transfer pattern is observed.

  Below, the evaluation method of the start acceleration performance of the tire based on the tire pattern transcribe | transferred on the snowy road surface is demonstrated. First, the test tire T is pressed on the snow road surface with a predetermined load in a free rolling and non-rotating state. In this state, the drive drum 4 is rolled about 1 m at a speed of about 0.2 m / s. Thereby, the tire pattern of the test tire T is transferred to the snow road surface. This transfer pattern is observed as follows.

  It is visually confirmed whether or not there are portions corresponding to the main groove and lug groove of the tread in the transfer pattern. The snow blocks corresponding to these grooves can be touched with fingers to determine whether they are fragile or difficult to break. It can be evaluated that the pattern is clearly transferred and the grip performance is good. It can be evaluated that the block-like portion which is not easily broken is better. This is because it is possible to determine that the tread of the test tire T firmly grips the snowy road.

  According to the method of forming the snow road 17 on the drive drum 4 described above, a new snow road surface can be formed easily and quickly. This is evident from the following examples.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
As Example 1, the snow road 17 was formed on the test drive drum 4 by the snow road forming method described above. The room temperature of the test room when the snowy road is formed, the rotational speed Vd of the drive drum 4, the lateral movement speed Vv of the cutting tool 21 for cutting the ice disk, the biting depth D of the cutting tool 21 into the ice disk 16, and the above rotating speed The ratio Vv / Vd is as shown in Table 2. The width W of the cutting tool 21 is 35 mm. Table 2 shows the snow road formation time (minutes) and snow quality under the above conditions.

[Example 2-8]
As Examples 2 to 8, the snow road 17 was formed on the test drive drum 4 by the snow road forming method described above. The room temperature of the test room when the snowy road is formed, the rotational speed Vd of the drive drum 4, the lateral movement speed Vv of the cutting tool 21 for cutting the ice disk, the biting depth D of the cutting tool 21 into the ice disk 16, and the above rotating speed The ratio Vv / Vd is as shown in Table 2. All other conditions are the same as in the first embodiment. Table 2 also shows snow road formation time and snow quality under the above conditions.

[Example 9-16]
As Examples 9 to 16, the snow road 17 was formed on the test drive drum 4 by the snow road forming method described above. The room temperature of the test room when the snowy road is formed, the rotational speed Vd of the drive drum 4, the lateral movement speed Vv of the cutting tool 21 for cutting the ice disk, the biting depth D of the cutting tool 21 into the ice disk 16, and the above rotating speed The ratio Vv / Vd is as shown in Table 3. All other conditions are the same as in the first embodiment. Table 3 also shows the snow road formation time and snow quality under the above conditions.

[Examples 17-20]
As Examples 17 to 20, the snow road 17 was formed on the test drive drum 4 by the snow road forming method described above. The room temperature of the test room when the snowy road is formed, the rotational speed Vd of the drive drum 4, the lateral movement speed Vv of the cutting tool 21 for cutting the ice disk, the biting depth D of the cutting tool 21 into the ice disk 16, and the above rotating speed The ratio Vv / Vd is as shown in Table 4. All other conditions are the same as in the first embodiment. Table 4 also shows snow road formation time and snow quality under the above conditions.

[Evaluation]
According to Tables 2 to 4, it can be seen that the faster the moving speed of the bite 21, the shorter the snow road formation time. The faster the drive drum 4 rotates, the much longer the snow road formation time is due to snow scattering. It turns out that it becomes. It can be seen that the biting depth of the bite 21 also affects the snow road formation time (Examples 9 and 10).

  The method for evaluating the performance of a tire on snow according to the present invention can be applied to the evaluation of the braking performance of any tire on snow.

DESCRIPTION OF SYMBOLS 1 ... Test apparatus 3 ... Tire support apparatus 4 ... Drive drum 5 ... Drum support apparatus 6 ... (Drum) drive apparatus 7 ... (Drum) bottom plate 8 ... Rotating shaft (for drum) 9 ... (for drum) bearing 10 ... (drum) opening 11 ... (for rim) rotating shaft 12 ... (for rim) drive device 13. .. Lifting device 14 ... Load cell 15 ... Ridge part 16 ... Ice plate 17 ... Snow road 18 ... Snow 21 ... Bite T ... Test tire

Claims (8)

An ice plate forming step for forming an ice plate on the inner peripheral surface of the drum for driving the tire;
A rotation step for rotating the drum at a constant speed;
An insertion step of biting a cutting tool from the surface of the ice plate outward in the radial direction of the drum;
A lateral movement step bytes that cutting the ice disc is moved at a constant speed in the width direction of the drum for rotating the bytes,
A snow road surface forming method for a tire test drum, comprising: a snow road surface forming step of laying snow generated by cutting the ice plate on an inner surface of the drum.   The method for forming a snow road for a tire test drum according to claim 1, wherein the rotational speed Vd of the drum is 3 m / s or more and 12 m / s or less.   The method for forming a snow road for a tire test drum according to claim 1 or 2, wherein a speed Vv of the horizontal movement of the cutting tool is 5 mm / s or more and 40 mm / s or less. The snow of the tire test drum according to any one of claims 1 to 3, wherein a ratio Vv / Vd of a lateral movement speed Vv of the bit with respect to a rotational speed Vd of the drum is 3.33 x ^10-3 or less. Road formation method.   The method for forming a snow road for a tire test drum according to any one of claims 1 to 4, wherein a depth of biting of the bite into the ice plate is 0.5 mm or more and 2.0 mm or less. A test device for running tires on snow,
A drum in which a snow road is formed on the inner peripheral surface;
A drum support device for rotatably supporting the drum;
A tire support device that rotatably supports the test tire and that can be pressed against the surface of the snow road;
A tire driving device for rotationally driving the test tire ;
And a bite movable in the radial direction and width direction of the drum ,
A test apparatus having a function of rotating the drum and cutting the ice formed on the inner peripheral surface of the drum with a cutting tool to generate snow that forms a snow path on the surface of the ice . A method for evaluating the performance of a tire on snow using a test device,
The test apparatus is the test apparatus according to claim 6,
A snow road surface forming step for laying snow on the ice surface;
A rotation driving step for rotating the test tire in a state where the outer peripheral surface of the test tire is pressed on the snow road on the inner peripheral surface of the drive drum;
During this rotational drive step, a measurement step for measuring the longitudinal force applied to the test tire from the inner peripheral surface,
A method for evaluating the on-snow performance of the tire, comprising: an evaluation step for evaluating the on-snow performance of the test tire based on the measured longitudinal force. The tire on-snow performance evaluation method according to claim 7, wherein, in the evaluation step, a maximum value of the longitudinal force measured during a predetermined traveling time is adopted.

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