JP2001030719A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire in which high-speed durability is improved without deteriorating other performance such as drainage and wear resistance. SOLUTION: A tread 18 of a pneumatic tire for a two-wheeled vehicle is provided with an inclined groove 20 that inclines in an arc shape from an equator CL toward tread ends 18A, 18B. The inclined groove 20 has a maximum- width portion 28 having the largest groove width formed in a first region constituting, from the equator CL, 15 to 30% of the half the tread width. By arranging the inclined groove 20 in the first region, heat-releasing performance can be improved most efficiently, and deterioration of wear resistance is suppressed. Furthermore, since a maximum width W1 of the maximum-width portion 28 is 1.5 to 2.5 times larger than a maximum width W2 of the inclined groove 20 in a second region except the first region, heat-releasing performance can be improved without deteriorating wear resistance. Consequently, heat-releasing performance can be enhanced effectively and high-speed durability can be improved without deteriorating other performance such as wear resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having improved high-speed durability by improving heat dissipation without impairing drainage and wear resistance.

[0002]

2. Description of the Related Art In recent years, with the increase in speed of vehicles, particularly motorcycles, it has become necessary to improve the high-speed durability of pneumatic tires from the viewpoint of safety.

[0003] As a method for improving high-speed durability, improvement in rubber used for a pneumatic tire (upper blow temperature) and improvement in pneumatic tire structure (upper rigidity) have been attempted. Has a large effect on the performance of
There was a disadvantage that it was difficult to make improvements.

[0004] Therefore, improvement in high-speed durability of a pneumatic tire has been attempted by improving the heat radiation property and suppressing the temperature rise of the pneumatic tire instead of improving the rubber or the tire structure.

[0005]

In order to improve the heat radiation of a pneumatic tire, it is effective to increase the negative ratio on the tread surface. However, increasing the negative ratio decreases the tread stiffness,
There is a disadvantage that the amount of tread deformation during rolling of the tire increases and the wear resistance decreases.

In view of the above, an object of the present invention is to provide a pneumatic tire having improved high-speed durability without impairing other performances such as drainage and abrasion resistance.

[0007]

In order to achieve the above object, according to the present invention, there is provided a tread surface having an arc-like shape inclined from the equatorial plane side to the shoulder side with respect to the tire circumferential direction. A pneumatic tire in which an inclined groove is formed, wherein the inclined groove is formed so as to extend from an equatorial plane to a first region of 15% to 30% of a tread development half width, and the inclination in the first region. The maximum width of the groove is at least 150% of the maximum width of the inclined groove in the second region excluding the first region in the range from the equatorial plane to the half width of the tread.

The operation of the first aspect of the present invention will be described.

An arc-shaped inclined groove is formed on the tread surface, and when the pneumatic tire rolls on a wet road surface, moisture in the ground contact surface passes through the inclined groove and smoothly moves from the equatorial surface side to the shoulder portion side. Is discharged. In order to improve the high-speed durability (heat dissipation) of the pneumatic tire without impairing other performances such as drainage and abrasion resistance, the fluctuation of the negative ratio and the like is minimized. It is necessary to efficiently form (arrange) the heat dissipation recess.

Therefore, it was determined as follows as to how far the arrangement of the heat-radiating concave portion from the equatorial plane would improve the heat-radiating property most effectively. That is, FIG.
As shown in (A), a straight rib 52 and a groove 54 extending in the tire circumferential direction are formed on a tread surface 50,
The relationship between the distance D along the tread surface 50 in the tire width direction between the center line GL of the groove 54 and the equatorial plane CL and the heat dissipation was examined. As shown in FIG. 3 (B), it was confirmed that when the groove 54 (center line GL) was arranged in a region of 0% to 30% of the tread development half width L from the equatorial plane CL, the heat radiation effect was the largest. Here, the tread development half width L is the equatorial plane C
In the plane orthogonal to L, the length of the arc along the tread from the equatorial plane CL to the end of the tread.

However, the vicinity of the equatorial plane of the motorcycle tire (from 0% to 15% of the tread development half width L from the equatorial plane CL).
%) Is a region where the motorcycle comes into contact with the ground when the motorcycle is traveling straight, and if a groove is arranged in this region, the rigidity of the tread surface is reduced, and the wear resistance tends to be significantly deteriorated.

Therefore, in the present invention, by setting the position (distance D) from the equator plane where the heat dissipation concave portion is formed to the first region of 15% to 30% of the tread development half width L, the wear resistance is not impaired. We have found that heat dissipation can be improved effectively.

Accordingly, by making the inclined groove the widest in the first region, specifically, the maximum width of the inclined groove in the first region is set to 150% or more of the maximum width of the second region excluding the first region. As a result, the change in the negative ratio can be suppressed, and the heat dissipation can be most effectively increased without impairing the drainage performance and the wear resistance. If the maximum width in the first region is less than 150% of the maximum width in the second region, it is not possible to sufficiently confirm the improvement in heat dissipation due to the increase in the groove width in the first region.

According to a second aspect of the present invention, in the first aspect of the invention, the maximum width of the inclined groove in the first area is 25 times the maximum width of the inclined groove in the second area.
0% or less.

The operation of the invention will be described.

The maximum width of the inclined groove in the first region is 2.50 times (250 times) the maximum width of the inclined groove in the second region.
%), The rigidity of the land portion defined by the inclined groove on the tread surface is locally reduced, and uneven wear is remarkably generated on the land portion. Therefore, if the maximum width in the first region is 1.50 times or more and 2.50 times or less the maximum width in the first region, the heat dissipation can be sufficiently enhanced without impairing the wear resistance. it can.

The third aspect of the present invention is the first or second aspect.
In the invention described above, an inclination angle of the inclined groove with respect to an equatorial plane is in a range of 40 degrees to 60 degrees.

The operation of the invention according to claim 3 will be described.

Since the arc-shaped inclined groove is formed from the equatorial plane side to the shoulder side side, when the pneumatic tire is used on a wet road surface, moisture can be quickly removed from the ground contact surface. Here, when the inclination angle of the inclined groove with respect to the equatorial plane exceeds 60 degrees, the drainage efficiency of the pneumatic tire decreases, and when it is less than 40 degrees, the wear resistance of the pneumatic tire is impaired. Therefore, the inclination angle of the inclined groove is set to 4
By setting the angle to 0 ° to 60 °, the pneumatic tire can ensure good drainage and abrasion resistance.

According to a fourth aspect of the present invention, in the first aspect of the invention, the groove width of the inclined groove is
It is characterized by being within the range of 3% to 10% of the half width of the tread development.

The operation of the invention will be described.

If the groove width of the inclined groove is less than 3% of the half width of the tread development, the groove is too thin to be able to discharge moisture in the ground contact surface properly. If it exceeds 10%, the rigidity of the tread surface is significantly reduced. Wear resistance is impaired. Therefore, if the groove width of the inclined groove is set to 3% to 10% of the half width of the tread deployment, the pneumatic tire can ensure good wear resistance and drainage.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the negative ratio of the tread surface is in a range of 10% to 25%.

The operation of the invention will be described.

The negative ratio on the tread surface is 10
If it is less than 25%, the drainage of the pneumatic tire is poor. If it exceeds 25%, the rigidity of the tread is significantly reduced, and the wear resistance of the pneumatic tire is impaired. Therefore, a negative ratio of 10
% To 25%, the pneumatic tire can ensure good drainage and abrasion resistance.

According to a sixth aspect of the present invention, in the first aspect of the invention, the inclined groove is formed so as to approach from the shoulder side to the equatorial plane side in the tire rotation direction. It is characterized by having been done.

The operation of the invention according to claim 6 will be described.

Since the inclined groove is formed so as to approach from the shoulder side to the equatorial plane side in the tire rotation direction, the inclined groove contacts the equatorial plane side of the inclined groove when rolling the tire, and the shoulder side is Ground later. As a result, the water in the ground contact surface flows from the equatorial plane side of the inclined groove to the shoulder side, and is quickly discharged.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the pneumatic tire is a pneumatic tire for a motorcycle.

The operation of the seventh aspect of the present invention will be described.

Since the tire for a motorcycle has a small ground contact area,
The degree to which the negative ratio or the like fluctuates greatly due to the formation of the heat dissipation recess. Therefore, there is a great possibility that the abrasion resistance and the drainage property are impaired by the formation of the heat dissipation recess. However, since the maximum width in the first region is only 150% or more of the maximum width in the second region, the heat radiation can be improved while suppressing a change in the negative ratio (abrasion resistance and drainage). Can be.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic tire for a motorcycle according to one embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 2, the pneumatic tire 10 for a motorcycle includes a pair of bead portions 12, a toroidal carcass 14 extending over both bead portions 12, and a carcass 1.
4 (two in this embodiment) located in the crown portion
And a tread portion 18 formed on the belt layer 16.

As shown in FIG. 1, the surface of the tread portion 18
A and 18B, an arc-shaped inclined groove 20 inclined to the equator plane CL side, a connection groove 22 inclined from the tread end side of the inclined groove 20 to the opposite side to the inclined groove 20, and an equatorial plane C of the inclined groove 20
Auxiliary groove 24 formed substantially parallel to connection groove 22 from the L side
And an auxiliary groove 26 which is arranged substantially parallel to the inclined groove 20 and is connected to the inclined groove 20 by the connection groove 22.
The inclined groove 20, the connecting groove 22, and the auxiliary grooves 24 and 26 are integrally formed at a predetermined pitch in the tire width direction. The inclined grooves 20, the connecting grooves 22, and the auxiliary grooves 24 are symmetrically shifted by half a pitch with respect to the equatorial plane CL. I have.

The inclined groove 20 is formed in an arc shape so that the average inclination angle θ formed with the equatorial plane CL is within a range of 40 degrees ≦ θ ≦ 60 degrees. If the average inclination angle θ is less than 40 degrees, the wear resistance of the tread portion 18 is insufficient, and
If the temperature is too high, sufficient drainage cannot be ensured. Therefore, by setting the average inclination angle θ to 40 degrees ≦ θ ≦ 60 degrees, sufficient abrasion resistance is ensured while ensuring good drainage.

The groove width W of the inclined groove 20 is not less than 3% and not more than 10% (0.03%) of the tread development half width L (see FIG. 2).
L ≦ W ≦ 0.10L). If the groove width W is less than 3% of the tread development half width L, the inclined groove 20
If the groove width W exceeds 10% of the tread half-width L, the rigidity of the tread is insufficient and the wear resistance is impaired. Note that the groove width W is
It refers to the average value of the groove width over the entire length of the inclined groove 20. Also,
The tread development half width refers to the length of an arc extending from the equatorial plane CL to the tread ends 18A and 18B along the surface shape of the tread portion 18 in a plane orthogonal to the equatorial plane CL.

Further, the negative ratio in the tread portion 18 is set in the range of 10% to 25%. this is,
If the negative ratio is less than 10%, it is not possible to sufficiently drain the water through the inclined groove 20, and if it exceeds 25%, the rigidity of the tread is insufficient and the wear resistance is impaired.

As described above, the pneumatic tire for a motorcycle 10
The pneumatic tire for a motorcycle is formed by forming the inclined groove 20 in the tread portion 18 so that the average inclination angle θ, the groove width W, and the negative ratio of the tread portion 18 are within predetermined ranges. 10 can secure good drainage and abrasion resistance.

The inclined groove 20 has a maximum width portion 28 having a maximum groove width in a first region from 15% to 30% of the tread development half width L from the equatorial plane CL (see FIG. 1). . That is, the distance D between the center of gravity (center) of the largest groove portion 28 and the equatorial plane CL is 15% to 30% of the tread development half width L.
%. This is because, as described in the means for solving the problem, the heat radiation by the groove is excellent in the region of 0% to 30% of the half width L of the tread development from the equatorial plane CL (see FIG. 3B). is there. However, the equatorial plane CL
Therefore, since the area of 0% to 15% of the tread development half width L is grounded when the motorcycle is traveling straight, if a new heat dissipation recess is provided in that area, the wear resistance may be significantly impaired. Therefore, from the equator plane CL, 15% to 3% of the tread development half width L
By arranging the maximum width portion 28 in which the groove width of the inclined groove 20 is maximum (at least the position of the center of gravity of the maximum width portion 28) in the 0% first region, heat dissipation can be effectively performed without impairing wear resistance. Can be improved.

Further, the maximum width portion 28 has a groove width (maximum width) W1 within a range from the equatorial plane CL to the tread development half width L except for the first region (hereinafter, referred to as a second region).
1.50 times (1) the maximum width W2 of
50%) or more and 2.50 times (250%) or less. This is because if the maximum width W1 is less than 1.50 times the comparison width W2, the heat dissipation cannot be sufficiently improved, and if it exceeds 2.50 times, the rigidity near the maximum width portion 28 decreases. Impairs wear resistance. Therefore, by setting the maximum width W1 to be 1.50 times or more and 2.50 times or less the comparison width W2, heat dissipation can be improved without deteriorating wear resistance.

The operation of the motorcycle pneumatic tire 10 thus formed will be described.

First, when the motorcycle pneumatic tire 10 is mounted on a motorcycle and travels on a wet road surface, the inclined groove 20 is turned toward the tread end 18 in the tire rotation direction R.
Since it is inclined from the A, 18B side to the equatorial plane CL side, the water in the ground contact surface is quickly discharged from the equatorial plane CL side of the inclined groove 20 to the tread ends 18A, 18B side. At this time, since the inclined groove 20 is formed in an arc shape and the groove width W is sufficiently ensured, drainage is impaired even if the water flow is slightly disturbed due to the maximum width portion 28. Never. Note that when the motorcycle turns, the contact area of the tread 18 moves in the tire width direction.
With the aid of the connection groove 22 and the auxiliary grooves 24 and 26, drainage can be quickly performed on both sides of the ground area.

Next, when the motorcycle pneumatic tire 10 is mounted on a motorcycle and travels on a dry road surface, the maximum width portion 28 having a maximum width W1 of 1.50 to 2.50 times the comparison width W2 is formed. Since it is provided in one region, heat dissipation can be effectively improved. As a result, the temperature rise of the motorcycle pneumatic tire 10 is suppressed, and the high-speed durability is improved.

Further, since the pneumatic tire 10 for a motorcycle has only the maximum width portion 28 provided in a part of the inclined groove 20, a negative ratio or the like for achieving both drainage and abrasion resistance falls within a predetermined range. It does not impair drainage and abrasion resistance.

In the present embodiment, as shown in FIG. 1, the maximum width portion 28 is formed as a portion protruding in a triangular shape in the middle of the inclined groove 20, but the groove width changes continuously. It may be a portion having the maximum groove width of the inclined groove 20. [Test] In order to confirm the effect of the present invention, the following test was conducted. The motorcycle tires of Comparative Examples 1 to 3 and Examples 1 to 3 used in the test have a tire size of MC.
R180 / 55ZR17, each having the same shape as that shown in the embodiment. Average inclination angle θ of the inclined groove 20, groove width W / tread development half width L, arrangement area of the maximum width portion 28 (distance from the equatorial plane D / tread development half width L),
The maximum width W1 / comparison width W2 and the negative ratio of the tread portion 18 are different.

Such Comparative Examples 1 to 3 and Examples 1 to
Using the motorcycle tire of No. 3, a test was conducted on the tire surface temperature, drainage performance, and wear resistance. The tire surface temperature was obtained by mounting the motorcycle tires of Comparative Examples 1 to 3 and Examples 1 to 3 on a motorcycle and measuring the surface temperature after traveling a predetermined distance. The drainage property is obtained by measuring a critical speed at which a hydroplaning phenomenon occurs when a motorcycle is run on a road surface having a water depth of 10 mm, and expressing the reciprocal thereof as an index. The abrasion resistance is a value obtained by performing an abrasion test by mounting each tire on a drum tester and converting the reciprocal of the abrasion amount into an index. Both the drainage property and the abrasion resistance indicate a large index.

[0047]

[Table 1]

When the comparative example 1 is compared with the examples 1 to 3, the comparative example 1 shows that the average inclination angle of the inclined groove, the negative ratio, and the ratio of the groove width W to the tread development half width L are all within predetermined ranges. , The maximum width W1 is 110% of the comparison width W2 (<
150%). As a result, although the drainage property and the abrasion resistance of Comparative Example 1 are good, the tire surface temperature becomes as high as 110 ° C. On the other hand, in Examples 1 to 3, the maximum width W1 was set to 150% or more and 250% or less of the comparative width W2, so that the tire surface temperature was reduced to 100 ° C. or less, and good heat dissipation was obtained, and good results were obtained. It was confirmed that drainage and abrasion resistance could be secured.

In particular, in Example 2 where the ratio of the maximum width W1 to the comparative width W2 was the largest, the tire surface temperature was reduced to 70 ° C., and it was confirmed that the ratio and the heat radiation were correlated.

When the comparative examples 2 and 3 are compared with the embodiment 1, the comparative example 2 shows that the maximum width portion 28 is 10% (<15%) of the tread development width L from the equatorial plane CL (the ground contact area when traveling straight). ), The tire surface temperature is reduced, but the uneven wear resistance is confirmed to be reduced. In Comparative Example 3, the maximum width portion 28 is the tread development width L from the equatorial plane CL.
Therefore, it was confirmed that the heat radiation effect due to the formation of the maximum width portion 28 was reduced and the tire surface temperature could not be sufficiently reduced. On the other hand, in Example 1, since the maximum width portion 28 was formed in a region 20% from the equatorial plane CL, it was confirmed that the tire surface temperature was sufficiently and effectively reduced without impairing the wear resistance.

In this embodiment, the description has been given of a pneumatic tire for a motorcycle. However, the present invention is not limited to the pneumatic tire, and is applicable to other pneumatic tires.

[0052]

According to the pneumatic tire of the present invention, the groove width is formed so as to be maximum in the first region of 15% to 30% of the half width of the tread from the equatorial plane, and the maximum width in the first region. Because the large width is at least 150% of the maximum width of the second region excluding the first region in the half width of the tread from the equatorial plane, fluctuations in the negative ratio, groove width, etc. can be suppressed, and drainage and abrasion resistance can be reduced. The heat radiation can be effectively improved without any loss. As a result, the high-speed durability of the pneumatic tire can be improved.

[Brief description of the drawings]

FIG. 1 is a tread developed view of a pneumatic tire for a motorcycle according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a pneumatic tire for a motorcycle according to an embodiment of the present invention.

FIG. 3A is an explanatory view of a test state for examining the relationship between a groove forming position and heat dissipation, and FIG. 3B is a view showing the test results.

[Explanation of symbols]

 Reference Signs List 10 Pneumatic tire for motorcycle (pneumatic tire) 18 Tread portion 20 Inclined groove 28 Maximum width portion

Claims (7)

[Claims] 1. A pneumatic tire having an arc-shaped inclined groove formed on a tread surface, which is inclined from an equatorial plane side to a shoulder section side with respect to a tire circumferential direction, wherein the inclined groove is an equatorial plane. From 15% of half width of tread development ~
The maximum width of the inclined groove in the first region is 30% of the first region, and the maximum width of the inclined groove in the first region is the maximum width of the inclined groove in the second region excluding the first region within a half width of the tread from the equatorial plane. A pneumatic tire characterized by being 150% or more. 2. The maximum width of the inclined groove in the first region is two times the maximum width of the inclined groove in the second region.
The pneumatic tire according to claim 1, wherein the content is 50% or less. 3. The pneumatic tire according to claim 1, wherein an inclination angle of the inclined groove with respect to an equatorial plane is in a range of 40 degrees to 60 degrees. 4. The pneumatic tire for a motorcycle according to claim 1, wherein a groove width of the inclined groove is in a range of 3% to 10% of a tread development half width. 5. The negative ratio of the tread surface is 10
% To 25%.
5. The pneumatic tire according to any one of 4). 6. The air according to claim 1, wherein the inclined groove is formed so as to approach the equatorial plane side from the shoulder portion side in the tire rotation direction. Containing tires. 7. The pneumatic tire according to claim 1, wherein the pneumatic tire is a pneumatic tire for a motorcycle.