JP5291474B2 - Pneumatic tires for motorcycles - Google Patents

Description

  The present invention relates to a pneumatic tire for a motorcycle, and more particularly to a pneumatic tire for a motorcycle that enables stable running on a wet road surface.

In a motorcycle road race, the vehicle runs at a speed exceeding 200 km / h on a wet road and competes for a lap time.
When passing over a puddle at such a high speed, hydroplaning may occur in the tire, losing grounding, and the vehicle body may behave in an unstable manner.

  In order to avoid this, 1 to 4 wet racing tires are arranged near the center of the ground contact surface that comes in contact with the straight line or zigzag groove parallel to the circumferential direction at the equator position on the tire cross section. To ensure drainage and deal with it.

  As conventional tires for motorcycles, for example, those disclosed in Patent Documents 1 and 2 are known.

JP-A-8-216629 JP 2006-142922 A

  However, the grooves arranged in parallel to the circumferential direction exhibit high drainage performance, but because the water is discharged not only to the rear but also to the front, it has the dilemma of stepping on the discharged water again. There was a request to further stabilize the running on the road surface.

  An object of the present invention is to provide a pneumatic tire for a motorcycle that ensures high drainage and does not step on drained water again in consideration of the above facts.

The pneumatic tire for a motorcycle according to claim 1 has a plurality of first inclined main grooves that are inclined toward one side in the tire width direction with respect to the tire circumferential direction and extend from the tire equatorial plane side toward the tread end side. A second inclined main groove group including a plurality of second inclined main grooves that are inclined toward the other side in the tire width direction with respect to the tire circumferential direction and extend from the tire equatorial plane side toward the tread end side. disposed inclined main groove group and the tire circumferential direction of the tread alternately and viewed from the tire width direction, said first inclined main groove group and the second inclined main groove group in the ground contact surface during straight Is arranged so that the tire circumferential direction length of the portion where the two do not overlap is greater than the tire circumferential direction length of the portion where the first inclined main groove group and the second inclined main groove group overlap,
The first inclined main groove and the second inclined main groove are arranged on the tire width direction center side of the tread and are inclined at a small angle with respect to the tire circumferential direction, and the steeply inclined groove portion It includes a gently inclined groove portion that is connected to a direction opposite to the tire rotation direction and extends toward the tread end with a larger angle with respect to the tire circumferential direction than the steeply inclined groove portion, and the steeply inclined groove portion is long in the tire circumferential direction. Is longer than the length in the tire circumferential direction of the ground contact surface when traveling straight, and is formed so as to enter the ground contact surface when traveling straight .

Next, the operation of the pneumatic tire for a motorcycle according to claim 1 will be described.
In the pneumatic tire for a motorcycle according to claim 1, the angle with respect to the tire circumferential direction of the inclined groove portion on the center side in the tire width direction of the tread is small, and the angle with respect to the tire circumferential direction of the inclined groove portion on the tread end side of the tread is large. And a first inclined main groove group including a plurality of first inclined main grooves extending from the tire equatorial plane side toward the tread end side, and the other side in the tire width direction with respect to the tire circumferential direction. Since the second inclined groove groups including the plurality of second inclined main grooves extending from the tire equatorial plane side toward the tread end side are alternately arranged in the tire circumferential direction of the tread, go straight Sometimes, the water on the center side in the tire width direction of the tread is efficiently taken into the steeply inclined groove portion extending at a small angle with respect to the tire circumferential direction, and the water taken into the steeply inclined groove portion is the rear of the tire and the gently inclined groove. The It is efficient drainage towards the tire side with.

For this reason, when going straight on the wet road surface, high drainage is ensured and the drained water is not stepped on again.
By adopting such a groove configuration, it is possible to exhibit higher drainage than the conventional pattern in which grooves parallel to the tire circumferential direction are arranged and to improve stability when traveling on a wet road surface at high speed. it can.
Further, by allowing the steeply inclined groove portion to enter the ground contact surface during straight travel, the drainage performance during straight travel can be further enhanced.

  According to a second aspect of the present invention, in the pneumatic tire for a motorcycle according to the first aspect, an angle of the steeply inclined groove portion with respect to the tire circumferential direction is within a range of 1 to 8 °.

Next, the operation of the pneumatic tire for a motorcycle according to claim 2 will be described.
By setting the angle of the steeply inclined groove portion with respect to the tire circumferential direction within a range of 1 to 8 °, high drainage can be reliably obtained without stepping on drained water again.
In addition, if the angle with respect to the tire circumferential direction of the steeply inclined groove portion is less than 1 °, the water is drained forward, and the effect of improving the stability of high-speed traveling on the wet road surface by stepping on the drained water cannot be obtained. On the other hand, if the angle of the steeply inclined groove portion with respect to the tire circumferential direction exceeds 8 °, the drainage itself deteriorates.

The invention according to claim 3 is the pneumatic tire for a motorcycle according to claim 1 or claim 2, wherein the first inclined main groove group and the second inclined main groove group are the steeply inclined groove portions. 2-6 each.

Next, the operation of the pneumatic tire for a motorcycle according to claim 3 will be described.
In the first inclined main groove group and the second inclined main groove group, if there are less than two steeply inclined groove portions, high drainage cannot be obtained. The stability of the steel deteriorates and uneven wear tends to occur.

  As described above, since the pneumatic tire for a motorcycle according to the present invention has the above-described configuration, it ensures high drainage and does not step on drained water again, thereby further stabilizing running on a wet road surface. Can do.

1 is a plan view of a pneumatic tire for a motorcycle according to an embodiment of the present invention. 6 is a plan view of a tread of a pneumatic tire for a motorcycle according to Conventional Example 1. FIG. FIG. 7 is a plan view of a tread of a pneumatic tire for a motorcycle according to Conventional Example 2.

An embodiment of a pneumatic tire for a motorcycle according to the present invention will be described with reference to the drawings.
The pneumatic tire 10 for a motorcycle according to the present embodiment has a tire size of 120 / 630R17M / C (for rear wheels).
Since the internal structure of the pneumatic tire 10 for a motorcycle according to the present embodiment is a general radial structure, description of the internal structure is omitted.

  As shown in FIG. 1, the tread portion 12 of the pneumatic tire 10 for a motorcycle according to the present embodiment is inclined to the right with respect to the tire circumferential direction (in FIG. 1, the arrow A direction is the tire rotation direction). A first inclined main groove group 16 including a plurality of (five in the present embodiment) first inclined main grooves 14 extending from the surface CL side toward the tread end 12E on the left side of the drawing, and the tire circumferential direction Second inclined main groove groups 20 including a plurality of second inclined main grooves 18 that are inclined to the left side and extend from the tire equatorial plane CL side toward the tread end 12E on the right side of the drawing are alternately arranged in the tire circumferential direction of the tread. Is arranged.

In addition, since the 1st inclination main groove group 16 and the 2nd inclination main groove group 20 are symmetrical shapes, the groove structure of the 1st inclination main groove group 16 is demonstrated on behalf of the following.
An intermediate portion in the longitudinal direction of the first inclined main groove 14 is disposed on the center side in the tire width direction of the tread portion 12, and is a substantially linear steeply inclined groove portion inclined at a small angle of 1 to 8 ° with respect to the tire circumferential direction. 22 is provided.

  A curved tread in which the angle with respect to the tire circumferential direction is larger than the steeply inclined groove portion 22 and the angle gradually increases in the tire rotating direction on the tire rotating direction side (arrow A direction side) of the steeply inclined groove portion 22. The central curved groove portion 24 is integrally connected. Note that the end of the tread center side curved groove portion 24 on the tire rotation direction side terminates near the center of the tread portion 12 in the width direction.

On the other hand, on the side opposite to the tire rotation direction side of the steeply inclined groove part 22, the angle with respect to the tire circumferential direction is larger than that of the steeply inclined groove part 22, and the angle gradually increases toward the direction opposite to the tire rotating direction. The curved tread end side curved groove portion 26 is integrally connected. Note that the end portion of the tread end side curved groove portion 26 on the opposite side to the tire rotation direction side opens to the tread end 12E on the left side of the drawing.
A length 22L in the tire circumferential direction of the steeply inclined groove portion 22 is formed to be longer than a length 28L in the tire circumferential direction of the ground contact surface 28 when traveling straight.
In the first inclined main groove group 16, it is preferable to set the number of the first inclined main grooves 14 so that four or more steeply inclined groove portions 22 enter the ground contact surface 28 when traveling straight.

  Here, the contact surface 28 refers to a tire contact surface when a tire is mounted on an applicable rim, set to a specified air pressure, placed perpendicular to a flat plate in a stationary state, and a specified mass is added. According to the standard, according to the 2008 JATMA YEAR BOOK, the tire is mounted on a standard rim, and the maximum load capacity in the applicable size / ply rating and the corresponding air pressure (maximum air pressure) are used as standards. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

In the tread portion 12, a plurality of inclined lug grooves 30 extending from the tread end 12E toward the tire equatorial plane CL and terminating in front of the tire equatorial plane CL are formed in the tire circumferential direction. The inclined lug groove 30 is inclined so that the end on the tire equatorial plane CL side contacts the tread end 12E.
A sub-inclined groove 32 is arranged on the right side of the first inclined main groove group 16 in the drawing. The sub-inclined groove 32 includes a steeply inclined groove part 34 extending parallel to the steeply inclined groove part 22 of the first inclined main groove 14 and a tread on the right side of the drawing from the end of the steeply inclined groove part 34 on the opposite side to the tire rotation direction side. It consists of a tread end side curved groove portion 36 extending toward the end 12E.

Note that the first inclined main groove group 16 and the second inclined main groove group 20 are alternately arranged in any one of them, a lateral force is generated by the tread pattern, and stable running is difficult. Because it becomes.
In addition, it is preferable that one or two first inclined main groove groups 16 and second inclined main groove groups 20 are installed in the tread portion 12.

(Function)
When the two-wheeled vehicle equipped with the two-ply pneumatic tire 10 of the present embodiment travels straight on the wet road surface, the water on the center side in the tire width direction of the tread portion 12 on the contact surface becomes the first inclined main groove 14 and the second main groove 14. The inclined main groove 18 is efficiently taken into the tread center side curved groove portion 24 and the steeply inclined groove portion 22 inclined at a small angle with respect to the tire circumferential direction, and the water taken into the steeply inclined groove portion 22 is the rear of the tire, Further, the water is efficiently drained to the tire side via the tread end side curved groove portion 26. For this reason, the drained water is not stepped on the tread portion 12 again.

  Further, the tire circumferential direction length 22L of the steeply inclined groove portion 22 is longer than the tire circumferential direction length 28L of the ground contact surface 28, and four or more steeply inclined groove portions 22 are included in the ground contact surface 28 when straightly traveling. With this configuration, drainage can be performed more efficiently toward the rear and side of the tire when traveling straight ahead.

  Therefore, the pneumatic tire 10 for a motorcycle according to the present embodiment exhibits higher drainage than a conventional pattern in which grooves parallel to the tire circumferential direction are disposed when traveling on a wet road at high speed, and has high stability. can get.

In the pneumatic tire 10 for a motorcycle according to the present embodiment, if the angle of the steeply inclined groove portion 22 with respect to the tire circumferential direction is less than 1 °, the water is also drained in front of the ground contact surface 28, and the drained water is stepped on the wet road surface. The effect of improving the stability of high-speed traveling cannot be obtained. On the other hand, if the angle of the steeply inclined groove portion 22 with respect to the tire circumferential direction exceeds 8 °, the drainage itself deteriorates.
The first inclined main groove 14 and the second inclined main groove 18 are preferably not branched in the middle because there is a concern about a decrease in drainage efficiency.

(Test Example 1)
In order to confirm the effects of the present invention, two types of tires of the examples to which the present invention was applied, two types of tires of comparative examples, and two types of conventional tires were prototyped, and an actual vehicle (ST600 regulation compliant specification, displacement 600 cc) ) Was mounted on the rear wheel, and the remaining ratio of the contact surface was measured.

The tires used in the test are as follows.
Example tire: having the tread pattern shown in FIG. 1 described in the above embodiment.
Tire of conventional example 1: having a tread pattern shown in FIG. In FIG. 2, reference numeral 100 denotes a circumferential groove, reference numeral 102 denotes a first inclined groove extending from the tread end toward the tire equatorial plane CL and ending before the circumferential groove 100, and reference numeral 104 denotes a first inclined groove. The second inclined groove is shorter than 102.
Tire of Conventional Example 2: It has a tread pattern shown in FIG. 3, reference numeral 104 denotes a circumferential groove, reference numeral 106 denotes an inclined lug groove, reference numeral 108 denotes a sub-inclined lug groove that connects the circumferential grooves 100, and reference numeral 110 denotes a sub-inclined lug that connects the inclined lug grooves 106 to each other. It is a groove.
Comparative Example 1: A tire in which the basic configuration is substantially the same pattern as the example, but the angle of the steeply inclined groove portion 22 with respect to the tire circumferential direction is set to 0 °.
Comparative Example 2: The basic configuration is a pattern substantially the same as that of the example, but the tire circumferential length of the steeply inclined groove portion 22 is set to 90% with respect to the tire circumferential direction length of the contact surface.
Each tire has a size of 170 / 630R17 and an internal pressure of 190 kPa.

The test method is as follows.
In the test, a room was established under the ground, a tempered glass window was placed so as to be flush with the ground, a colored water pool with a depth of 10 mm was created on the glass, and an actual vehicle was passed over it. The ground plane was taken with a high-speed camera.
The contact surface remaining rate is a ratio between the area where water is discharged and contacted to the road surface (glass) and the contact area when passing without water accumulation. The ratio is expressed as an index. The larger the value, the larger the contact area and the better drainage.

試験の結果から、本発明の適用された実施例のタイヤは、ウエット路面を高速走行した際の排水性に優れていることが分かる。

From the test results, it can be seen that the tire of the example to which the present invention is applied is excellent in drainage performance when traveling on a wet road surface at high speed.

(Test Example 2)
In order to confirm the effect of the present invention, a test tire was mounted on an actual vehicle in the same manner as in Test Example 1, and a wet circuit course was run, and the best lap time was compared between a new product and 20 laps. Note that the evaluation is represented by an index with the reciprocal of the lap time at the time of a new article of Conventional Example 1 being 100, and the larger the index value, the better the time.

本願発明の適用された実施例のタイヤは、全ての陸部がタイヤ１周に渡って連続してつながっており、溝により分断されていない特徴を有している。それにより、分断された部分を有するトレッドパターンに比べて偏摩耗が生じ難く、偏摩耗による摩耗後のラップタイムの悪化を抑制することができる。

The tire of the embodiment to which the present invention is applied has a feature that all land portions are continuously connected over one circumference of the tire and are not divided by a groove. Thereby, compared with a tread pattern having a divided portion, uneven wear is less likely to occur, and deterioration of lap time after wear due to uneven wear can be suppressed.

DESCRIPTION OF SYMBOLS 10 Two-wheeled pneumatic tire 12E Tread end 12 Tread part 14 1st inclination main groove 16 1st inclination main groove group 18 2nd inclination main groove 20 2nd inclination main groove group 22 Steep inclination groove part 24 Tread center side Curved groove 26 Tread end curved groove 28 Grounding surface

Claims (3)

A first inclined main groove group including a plurality of first inclined main grooves that are inclined toward one side in the tire width direction with respect to the tire circumferential direction and extend from the tire equatorial plane side toward the tread end side; and the tire circumferential direction And a second inclined main groove group including a plurality of second inclined main grooves extending from the tire equatorial plane side toward the tread end side in the tire circumferential direction of the tread. The tire circumferential direction length of the portion where the first inclined main groove group and the second inclined main groove group do not overlap with each other in the tire width direction , which are alternately arranged and seen from the tire width direction, The first inclined main groove group and the second inclined main groove group are arranged so as to be larger than the length in the tire circumferential direction of the overlapping portion,
The first inclined main groove and the second inclined main groove are arranged on the tire width direction center side of the tread and are inclined at a small angle with respect to the tire circumferential direction, and the steeply inclined groove portion It includes a gently inclined groove portion that is connected to a direction opposite to the tire rotation direction and extends toward the tread end with a larger angle with respect to the tire circumferential direction than the steeply inclined groove portion, and the steeply inclined groove portion is long in the tire circumferential direction. A pneumatic tire for a motorcycle, wherein the tire is longer than the tire circumferential length of the ground contact surface when traveling straight, and is formed so as to enter the ground contact surface when traveling straight .   The pneumatic tire for a motorcycle according to claim 1, wherein an angle of the steeply inclined groove portion with respect to a tire circumferential direction is within a range of 1 to 8 °. The pneumatic tire for a motorcycle according to claim 1 or 2, wherein each of the first inclined main groove group and the second inclined main groove group includes 2 to 6 steeply inclined groove portions.

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