JP5141400B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having an asymmetric pattern with respect to a tire center, in which the vehicle inner side mounting and the vehicle outer side mounting are determined on both sides of the tire, and more particularly, uneven wear resistance and wet on a wet road surface. The present invention relates to a pneumatic tire having a tread pattern that balances performance.

Tires are required to improve tire steering stability performance, tire vibration riding comfort performance including road noise, tire braking performance, tire durability performance, tire uneven wear resistance performance, wet performance, and the like.
In the tire uneven wear resistance performance, it is examined whether or not the wear is concentrated on a certain portion from the amount of rubber wear on the tread portion after a certain travel. When wear progresses unevenly, vibrations are generated in the tire, and the tire vibration riding comfort is deteriorated, and the tire life is extremely shortened.
For wet performance, the handling performance and hydroplaning performance on wet road surfaces are examined. In particular, tire wear resistance and wet performance are particularly demanding in the United States and Canada.

Patent Literature 1 below proposes a pneumatic tire that improves wet performance without impairing wear resistance.
According to this, a central vertical main groove extending on the tire equator and outer vertical main grooves on both sides thereof are provided, and a lug groove that does not reach the central vertical main groove from the outer vertical main groove is provided. The lug groove includes a curved portion that is curved with an inclination angle of 30 to 50 ° with respect to the tire circumferential direction and gradually decreasing the inclination angle at the intersection with the outer longitudinal main groove, and a linear portion that continues to the curved portion. Including. The curved portion includes a first curved portion whose groove width is 60 to 80% of the longitudinal main groove and a second curved portion whose groove width is 25% or more and smaller than 60% of the longitudinal main groove. The groove width of the straight portion is 25% or less of the longitudinal main groove, and the groove depth is smaller than the groove depth of the first curved portion.
In the pneumatic tire having such a tread pattern structure, it is said that the wet performance can be improved without impairing the wear resistance.

Japanese Patent No. 3035278

  Although the pneumatic tire improves the wet performance without impairing the wear resistance, it is required to achieve higher wear resistance and wet performance in markets such as the United States and Canada.

  Then, an object of this invention is to provide the pneumatic tire which achieves abrasion resistance performance and wet performance in high dimension.

In order to achieve the above object, the present invention provides a pneumatic tire having an asymmetric pattern with respect to a tire center, wherein the vehicle inner side mounting and the vehicle outer side mounting are determined on both sides of the tire. On the other hand, when the pattern corresponding to the vehicle inner side is defined as the inner pattern side and the pattern corresponding to the vehicle outer side is defined as the outer pattern, the inner pattern is provided with at least two circumferential grooves. At least three inner land portion rows are formed by the circumferential groove and the ground contact end in the tire width direction, and each of the inner land portion rows has an inner circumferential groove in contact with the inner land portion row, and the inner land portion. At least one inner lag groove provided across the row or at least one first sipe that communicates with the ground contact end in the tire width direction;
The outer pattern is provided with at least one outer circumferential groove, and at least two outer land rows are formed by the outer circumferential groove and the ground contact end in the tire width direction. The outer circumferential groove contacting the outer land row, the outer lug groove crossing the outer land row, or one end communicates with the grounding end in the tire width direction, and the other end is the outer circumferential groove. A second sipe that is closed without communicating with the outer lug groove and the grounding end is provided, and the second sipe is bent and closed in the vicinity of the other end. Provide pneumatic tires.

In the inner pattern, the first sipe has an inner circumferential groove that contacts the inner land portion row, an inner lug groove that crosses the inner land portion row, or the total number of open ends that communicate with the ground contact end in the tire width direction. Is determined for each inner land portion row, the total number in the inner land portion row closest to the grounding end is larger than the total number in the inner land portion row closest to the tire center,
When the total number is compared among all the adjacent inner land portion rows, the total number in the inner land portion row located on the grounding end side is the total number in the inner land portion row located on the tire center side. Is preferably greater than or the same.

  Furthermore, it is preferable that the length of the second sipe in the outer pattern bends in the vicinity of the other end is 2 mm or more.

  Further, among the second sipes, sipes provided in adjacent outer land portion rows across the circumferential groove of the outer pattern extend at least in the tire width direction, and the adjacent outer land in this sipe. Ends located on the outer circumferential groove side sandwiched between the sub-rows are all arranged to be bent and closed ends, or both are connected to the outer circumferential groove. It is preferable that they are arranged.

  The extending direction of the bent portion of the second sipe in the vicinity of the other end is a direction inclined from the tire circumferential direction to the tire width direction, and the inclined direction of the bent portion is the second sipe. It is preferable that all are aligned.

  Further, in the inner pattern, the inner land portion row is provided with a third sipe that branches from the middle of the first sipe, and the third branch that branches within the grounding width of the inner pattern. It is preferable that the sipe extends toward the ground contact end side in the tire width direction.

In the present invention, the first sipe of the inner land portion row communicates at both ends with an inner circumferential groove, an inner lug groove provided so as to cross the inner land portion row, or a ground contact end in the tire width direction. The second sipe has an outer circumferential groove, an outer lug groove crossing the outer land portion row, or one end connected to the grounding end in the tire width direction, and the other end is an outer circumferential groove and an outer lug groove. And it is bent and closed without communicating with the grounding end. With this sipe configuration, wear resistance and wet performance can be achieved at a high level.
In that case, in the inner pattern, the total number of the inner circumferential direction groove where the first sipe is in contact with the inner land portion row, the inner lug groove crossing the inner land portion row, or the open end communicating with the grounding end in the tire width direction, When determined for each land section row, the total number in the inner land section row closest to the ground contact is larger than the total number in the inner land section row closest to the tire center, and between all adjacent inner land section rows, When the total number is compared, the total number in the inner land portion row located on the side of the ground contact is greater than or equal to the total number in the inner land portion row located on the tire center side. Thereby, wet performance can be improved more effectively.

  Hereinafter, the pneumatic tire of the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

FIG. 1A shows a pneumatic tire (hereinafter referred to as a tire) 10 which is an embodiment of the pneumatic tire of the present invention. The tire 10 can be suitably used for a passenger car tire. The dimensions of the groove width and groove depth of the tire described below are numerical examples of the tire for passenger cars.
In the tire 10, a pattern 14 that is a feature of the present invention is formed in the tread portion 12.
As the structure of the tire 10 and the rubber member, a known one may be used, or a new one may be used, and there is no particular limitation in the present invention.
In the present invention, the tire width direction refers to a direction parallel to the tire rotation axis, and the tire circumferential direction refers to a circumferential direction of rotation when the tire is viewed as a rotating body.

FIG. 1B is a diagram in which the pattern 14 of the tire 10 is developed in an easy-to-understand manner. As shown in FIG.1 (b), the asymmetrical pattern from which pattern shape differs on either side with respect to tire center CL is comprised. That is, when the tire 10 is mounted on the vehicle, the vehicle inner side mounting and the vehicle outer side mounting are determined on both sides of the tire.
In FIG. 1 (b), the tire 10 is mounted such that the right side portion of the tire is on the outside of the vehicle and the left side portion of the tire is on the inside of the vehicle. In the drawing, a circumferential groove, a lug groove, and an arcuate curved groove to be described later are indicated by black areas, and a portion where the tread portion is in contact with the ground (hereinafter, this portion is referred to as a land portion) is indicated by a white region. Therefore, in FIG. 1B, the pattern on the right side of the tire with the tire center CL as a boundary is referred to as an outer pattern, and the pattern on the left side of the tire is referred to as an inner pattern.

  The ratio of the groove area to the groove area and land area of the inner pattern (groove area ratio) is 30 to 40%, and the groove area ratio of the outer pattern is 25 to 35%. The reason why the groove area ratio of the outer pattern is lower than the groove area ratio of the inner pattern is that the ground contact area becomes larger while the vehicle is turning, and it is necessary to increase the rigidity of the pattern so that it can resist the generated lateral force. Because there is.

The pattern 14 mainly includes a tread center portion 20, first land portion rows 22a and 22b, second land portion rows 24a and 24b, and circumferential grooves 26a, 26b, 28a, and 28b.
The tread center portion 20 is a land portion that is sandwiched between two circumferential grooves 26a and 26b and through which the tire center CL passes. The first land portion row 22a is sandwiched between the circumferential grooves 26a and 28a, and the first land portion row 22b is sandwiched between the circumferential grooves 26b and 28b. The second land portion row 24a is in contact with the circumferential groove 28a, and the second land portion row 24b is in contact with the circumferential groove 28b.
The outer pattern of the tire 10 is provided with two circumferential grooves 26a and 28a. However, in the present invention, the number of circumferential grooves in the outer pattern may be at least one or more. The number of circumferential grooves may be at least two.

The lug groove 30 is provided closed from the end of the tread center portion 20 in contact with the one circumferential groove 26b without crossing the tire center CL.
A plurality of arcuate curved grooves 32 are provided in the tire circumferential direction from the end of the tread center portion 20 that contacts the other circumferential groove 26a. Each arcuate curved groove 32 extends from the end in contact with the circumferential groove 26a in a direction inclined toward the inner side in the tire width direction (the tire center CL side) with respect to the tire circumferential direction, and faces the tire circumferential direction in the middle. Then, it extends toward the direction inclined toward the outer side in the tire width direction (tread shoulder side). The arcuate curved groove 32 is provided so as to merge with the arcuate curved groove 32 adjacent in the tire circumferential direction without traversing the tire center CL. A sipe 35 is provided in a block defined by one arcuate curved groove 32, an arcuate curved groove 32 adjacent thereto, and a circumferential groove 26a. The sipe 35 is bent halfway, and both ends communicate with the arcuate curved groove 32 adjacent to the circumferential groove 26a. The groove width of the sipe 35 is 0.4 to 1.4 mm, and the depth is 3 to 7 mm.

Each arcuate curved groove 32 is inclined by 5 to 45 degrees, preferably 15 to 35 degrees, inward in the tire width direction (tire center side) with respect to the tire circumferential direction, and extends from an end portion in contact with the circumferential groove 26a.
The arcuate curved groove 32 may end at the junction with the adjacent arcuate curved groove 32, but may further extend through the junction. However, the tip end is blocked in the middle without joining the adjacent arcuate curved groove 32 adjacent thereto. Since the arcuate curved groove 32 merges with the adjacent arcuate curved groove 32, drainage performance on wet road surfaces is improved and wet performance is improved.

In the vicinity of the junction with the circumferential groove 26a, the arcuate curved groove 32 reduces the tread rigidity in the tire circumferential direction and improves the edge effect in the same manner as the lug groove, thereby improving the wet performance.
On the other hand, since the arcuate curved groove 32 faces the tire circumferential direction in the vicinity of the tread center CL, the tread rigidity in the tire width direction decreases. Further, the arcuate curved groove 32 merges with the adjacent arcuate curved groove 32, thereby forming a block surrounded by the arcuate curved groove 32, the adjacent arcuate curved groove 32, and the circumferential groove 26a. Therefore, the tread rigidity in the tire width direction decreases. For this reason, the wet performance on a wet road surface can be improved by the edge effect.

  Here, the arcuate curved groove 32 is provided so as to pass through the vicinity of the tread center CL but never cross. When the tire center CL is crossed, the tread rigidity in the tire width direction is greatly reduced, and the steering stability is lowered. Whether or not there is a groove in the tire center CL sensitively affects the steering response when the vehicle is steered straight from the steering stability. Further, unlike the conventional tire, the tire center CL does not have a circumferential groove, and has a continuous rib-like land portion, so that a nucleus that causes uneven wear is not formed.

The arcuate curved groove 32 has a shallower groove depth from the junction with the circumferential groove 26a toward the tire center CL. For example, the groove depth is shallow in steps. The groove depth may be smooth and shallow. For example, at the junction with the circumferential groove 26a, the groove depth of the arcuate curved groove 32 is 6.0 to 8.0 mm while the groove depth of the circumferential groove 26a is 8.0 to 9.5 mm. In the vicinity of the tire center CL, the distance is 3.0 to 6.0 mm. Thus, the groove depth is made shallow near the tire center CL. As a result, the tread rigidity in the vicinity of the tire center CL does not decrease, and the steering stability does not decrease.
Note that the portion from the tire center CL toward the tire circumferential groove 26a (toward the tire width direction outer side) until it merges with the adjacent arcuate curved groove 32 is the groove depth in the vicinity of the tire center CL. In addition, the groove depth is further reduced. Since the groove depth at the joining portion of the adjacent arcuate curved grooves 32 is deep, the tread rigidity is prevented from being lowered more than necessary.

Further, the groove wall in the vicinity of the confluence portion of the arcuate curved groove 32 is inclined so that the groove width becomes narrow, and as shown in FIG. 2, the groove wall inclination angle θ ₁ inside the curve of the arcuate curved groove is It is larger than the groove wall inclination angle θ ₂ outside the curve. FIG. 2 is a view for explaining the groove cross-sectional shape of the arcuate curved groove 32. The groove wall inclination angle on the inner side of the curve decreases as the distance from the joining portion increases. On the other hand, the groove wall inclination angle outside the curve of the arcuate curved groove does not change.
For example, the groove wall inclination angle θ _{1 at} the junction is 5 to 20 degrees, the groove wall inclination angle θ ₂ is 0 to 5 degrees, and the groove wall inclination angle θ ₃ of the groove inner wall in the vicinity of the tire center CL. Is 0-5 degrees.
In this way, the inclination angle of the inner groove wall of the arcuate curved groove is made larger than the inclination angle of the outer groove wall of the arcuate curved groove, and the inclination angle of the inner groove wall becomes smaller as it moves away from the junction. The reason for this is to prevent the tread rigidity in the tire width direction in the vicinity of the merging portion from becoming weak in order to ensure steering stability. Further, the tread rigidity in the vicinity of the joining portion of the block sandwiched between the arcuate curved groove 32 and the circumferential groove 26a becomes extremely weak, so that it does not become the core of occurrence of uneven wear.

Further, as shown in FIG. 3, the groove wall inside the curved portion where the arcuate curved groove 32 meets the circumferential groove 32 is chamfered with a shape having a curvature and goes in the direction of the groove depth. Therefore, the curvature is small (the radius of curvature is large).
By providing the chamfer R in this way, it is possible to prevent the tread rigidity in the vicinity of the merging portion from being weakened and not to become a core of occurrence of uneven wear.
The circumferential grooves 26a and 26b sandwiching the tread center portion 20 have a groove width of 5 to 15 mm and a groove depth of 8.0 to 9.5 mm.

The lug grooves 30 are a plurality of grooves provided in the tire circumferential direction so as to be closed without crossing the tire center CL from the end portion of the tread center portion 20 in contact with the circumferential groove 26b. The groove width is 1.0 to 5.0 mm, and the groove depth is 3.0 to 8.0 mm. Each lug groove 30 extends with an inclination of 5 to 45 degrees, preferably 15 to 35 degrees, inward in the tire width direction (tire center side) with respect to the tire circumferential direction from an end portion in contact with the circumferential groove 26b. The inclination direction is opposite to the inclination direction at the junction of the arcuate curved groove 32.
By providing the lug groove 30, the wet performance can be improved by the edge effect.
A sipe 33 is provided between the lug groove 30 and the adjacent lug groove 30 and is closed without crossing the tire center CL. Note that the end of the sipe 33 is bent and closed. The groove width of the sipe 33 is 0.4 to 1.4 mm, and the depth is 3.0 to 7.0 mm.
In addition, the pitch length between the arcuate curved groove 32 adjacent to the arcuate curved groove 32 and the pitch length between the lug groove 30 adjacent to the lug groove 30 are substantially the same.

The first land portion rows 22a, 22b are block rows provided outside the tread center portion 20 in the tire width direction and surrounded by two circumferential grooves 26a, 28a, 26b, 28b and lug grooves 34a, 34b. It is. The first land portion rows 22a and 22b are disposed at substantially line symmetrical positions with the tire center CL interposed therebetween. In the present invention, the lug grooves 34a and 34b correspond to the second lug grooves.
The lug grooves 34a and 34b are linear grooves or curved grooves having a slight curvature from the straight line, and the lug grooves 34a and lug grooves 34b are opposite in the direction inclined from the tire width direction to the tire circumferential direction. ing. It is inclined at an absolute value of 45 to 85 degrees in the tire circumferential direction from the tire width direction. The groove width is 2.0 to 7.0 mm, and the groove depth is 3.0 to 7.0 mm. The lug groove 34b has an extremely narrow groove width in the vicinity of joining the circumferential groove 26b, for example, 2.0 mm.
It is preferable that the groove width of the lug groove 34b located outside the vehicle is narrower than the lug groove 34a located inside the vehicle. The tire ground contact portion during cornering needs to generate a large lateral force at the tread portion outside the vehicle where the ratio of the tire ground contact surface during cornering increases. For this reason, in order to reduce the groove area on the side corresponding to the vehicle outer side, the groove width of the lug groove 34b located on the vehicle outer side is made narrower than the lug groove 34a located on the vehicle inner side.

In addition, sipes 36a, 36b, and 37a are provided in blocks that are the land portions of the first land portion rows 22a and 22b. The sipes 36a, 36b, and 37a have a groove width of 0.4 to 1.4 mm and a depth of 3.0 to 7.0 mm. Sipe can improve the wet performance by the edge effect by appropriately adjusting the tread rigidity in the block.
The first land portion row 22a on the side where the arcuate curved groove 32 is provided is provided with a sipe 36a communicating with the circumferential grooves 26a and 28a surrounding the first land portion row 22a. The sipe 37a branches off from the middle of the sipe 36a, extends to the ground contact end side in the tire width direction, and communicates with the circumferential groove 28a. One end of the sipe 36b communicates with the circumferential groove 26b, and the other end is bent and closed halfway without communicating with the circumferential groove 28b. The term “grounding end” refers to the end of the grounding surface on the tire shoulder side where the grounding width in the tire width direction is the largest on the grounding surface when the tire 10 is grounded on a horizontal surface under a predetermined condition. Here, the predetermined condition means an internal pressure condition of 200 kPa and a load condition of 85% of the maximum load specified by JATMA, TRA, or ETRTO.
The reason why the sipe 36b does not communicate with the circumferential groove 28b is to prevent the tread rigidity of the tread portion outside the vehicle, which greatly contributes to the generation of lateral force, from decreasing the tire ground contact surface during turning. . Moreover, it is for suppressing the partial wear by the fall of tread rigidity. In addition, by bending the vicinity where the sipe 36b is closed, the edge effect is exerted and the wet performance is improved.
On the other hand, a sipe 36a that communicates with the circumferential grooves 26a and 28a is provided in the tread portion inside the vehicle that does not contribute much to the generation of lateral force during turning in order to ensure wet performance.

The second land portion rows 24a and 24b are block rows or continuous land portion rows formed by circumferential grooves 28a and 28b and lug grooves 38a and 38b outside the first land portion rows 22a and 22b in the tire width direction. . The second land portion rows 24a and 24b are disposed at substantially line symmetrical positions with the tire center CL interposed therebetween. In the present invention, the lug groove 38b corresponds to the third lug groove, and the lug groove 38a corresponds to the fourth lug groove.
The lug grooves 38a and 38b are curved grooves having a slight curvature from a straight line, and the lug grooves 38a and the lug grooves 38b have asymmetric shapes. The groove width is 2.0 to 7.0 mm, and the groove depth is 3.0 to 7.0 mm. The lug groove 38a does not communicate with the circumferential groove 28a, and therefore the second land portion row 24a is a land portion row in which land portions are continuously connected in the tire circumferential direction. The second land portion row 24b is a block row composed of blocks surrounded by the circumferential groove 28b and the lug groove 38b.
In the present embodiment, the lug groove 38a does not communicate with the circumferential groove 28a, but the lug groove 38a may communicate with the circumferential groove 28a. Further, in this case, the lug groove 38a may be configured such that the groove depth of the lug groove 38a is shallow in the vicinity of the lug groove 38a communicating with the circumferential groove 28a.
The lug groove 38b located outside the vehicle is narrower than the lug groove 38a located inside the vehicle. The tire ground contact portion during cornering needs to generate a large lateral force at the tread portion outside the vehicle where the ratio of the tire ground contact surface during cornering increases. For this reason, in order to reduce the groove area of the outer pattern corresponding to the vehicle outer side, the groove width of the lug groove 38b located on the vehicle outer side is made narrower than the lug groove 38a located on the vehicle inner side.
Note that the second land portion rows 24a and 24b are not defined by circumferential grooves on the tire shoulder side, but the tire's ground contact end in the tire width direction is usually on the second land portion rows 24a and 24b. Therefore, when viewed from the ground contact surface, the second land portion rows 24a and 24b form a land portion row such as a block row or a continuous land portion row.
The 1st land part row | line | column 22a, 22b and the 2nd land part row | line | column 24a, 24b improve wet performance by drainage property and an edge effect with the arcuate curved groove | channel 32 and the lug groove 30. FIG.

In addition, sipes 40a, 40b, and 41a are provided in the blocks that are the land portions of the second land portion rows 24a and 24b. The sipes 40a, 40b, and 41a have a width of 0.4 to 1.4 mm and a depth of 3.0 to 7.0 mm. The sipe can improve the wet performance by appropriately adjusting the tread rigidity in the block.
The second land portion row 24b is provided with a sipe 40b whose both ends are closed, and one end of the sipe 40b does not communicate with the circumferential groove 28b but is bent and closed, and the other end of the sipe 40b is bent. Then, it communicates with the lug groove 38b.
On the second land portion row 24a on the side where the arcuate curved groove 32 is provided, sipes 40a and 41a communicating with the circumferential groove 28a adjacent to the second land portion row 24a are provided. The sipe 41a branches off from the middle of the sipe 40a and communicates with the circumferential groove 28a.
The reason why the sipe 40b does not communicate with the circumferential groove 28b is to prevent the tread rigidity of the tread portion outside the vehicle, which greatly contributes to the generation of lateral force, from decreasing the tire ground contact surface during turning. . Moreover, it is for suppressing the partial wear by the fall of tread rigidity. On the other hand, sipes 40a and 41a communicating with the circumferential groove 28a are provided in the tread portion inside the vehicle that does not contribute much to the generation of lateral force during turning in order to ensure wet performance.

In such a pattern 14 of the tire 10, the inner land portion row in the inner pattern has a tread sentab 20 portion on the left side in FIG. 1B with the tire center CL as a boundary, a first land portion row 22 a, The second land portion row 24b corresponds. The inner circumferential grooves correspond to the circumferential grooves 26a, 28a, the inner lug grooves correspond to the lug grooves 34a, 38a, and the first sipes correspond to the sipes 35, 36a, 40a.
The outer land portion row in the outer pattern corresponds to the tread sentab 20 portion on the right side in FIG. 1B with respect to the tire center CL, the first land portion row 22b, and the second land portion row 24b. . The outer circumferential grooves correspond to the circumferential grooves 26b, 28b, the outer lug grooves correspond to the lug grooves 30, 34b, 38b, and the second sipes correspond to the sipes 33, 36b, 40b.

Here, regarding the inner pattern, the tire 10 has an inner circumferential groove or an inner lug groove for each portion of the tread center portion 20, the first land portion row 22a, and the second land portion row 24a. When the total number of communication is obtained, the total number in the second land portion row 24a is larger than the total number in the tread center portion 20, and between the adjacent land portion rows, the land portion row located on the grounding end side is more. The total number is larger than that of the land portion row located on the tire center CL side.
In the pattern shown in FIG. 1B, the total number of pitches in the tread center portion 20 for one pitch is 2 because the sipe 35 communicates with the arcuate curved groove 32 and communicates with the circumferential groove 26a. The total number in the first land portion row 22a is 3 because the sipe 36a communicates with the circumferential grooves 26a and 28a and the sipe 37a communicates with the circumferential groove 28a. The total number in the second land portion row 24a is 4 because the sipe 40a communicates with the circumferential groove 28a and the outside of the ground plane, and the sipe 41a communicates with the circumferential groove 28a and the outside of the ground plane. Therefore, the total number in the second land portion row 24a is larger than the total number in the tread center portion 20, and the total number 3 in the first land portion row 22a is the total number 2 in the tread center portion 20 and the total number in the second land portion row 24a. The number is between four. Thus, by adjusting the number of sipes communicating with the circumferential grooves and lug grooves, the wet performance can be improved by the edge effect on the wet road surface.
In the present invention, in the inner pattern, the total number in the land portion row closest to the ground contact edge is larger than the total number in the land portion row closest to the tire center CL, and the total number is between all adjacent land portion rows. , The total number in the land portion row located on the ground contact end side may be greater than or equal to the total number in the land portion row located on the tire center CL side.

Further, the sipes 33, 36b, and 40b in the outer pattern all have one end communicating with the circumferential grooves 26b and 28b or the grounding end, the other end has a bent portion, and is closed by the bent portion. . At this time, the length of the bent portion is preferably 2 mm or more. By blocking the sipe, it is possible to improve uneven wear resistance, and by providing the sipe with a bent portion having the above-mentioned length and closing it, the wet performance can be improved by the edge effect of the sipe. . When the bent portion is shorter than the above length, the improvement in wet performance is small.
In addition, it is preferable that the angle (bending angle) before and after bending of the sipe is 60 to 120 degrees. When the bending angle is smaller than the above range, the sipe is likely to crack, and when the bending angle is larger than the above range, the effect of improving the wet performance by bending is reduced.

  Of the sipes 33, 36b, 40b in the outer pattern, the sipes 33, 36b (or sipes 36b, 40b) provided in the adjacent land portion rows with the circumferential groove 26b (or the circumferential groove 28b) in between are It extends at least in the tire width direction, and the ends of the sipes 33 and 36b (or sipes 36b and 40b) located on the side of the circumferential groove 26b (or the circumferential groove 28b) are provided with bent portions. It is preferable that they are arranged so as to be closed, or both are arranged so as to communicate with the outer circumferential groove. In the pattern 14 of FIG. 1B, the sipe 33 in the tread center portion 20 and the sipe 36b in the first land portion row 22b communicate with the circumferential groove 26b, and the sipe in the first land portion row 22b. The ends close to the circumferential groove 28b of the sipe 40b of 36b and the second land portion row 24b are closed ends.

Further, the bent portions of the sipes 33, 36b, and 40b in the outer pattern are all inclined in the tire width direction from the tire circumferential direction, and the inclined directions are preferably all aligned in the sipes 33, 36b, and 40b. By aligning the inclination direction, the wet performance can be exhibited stably and effectively.
Further, in the outer pattern, a chamfer 40 is provided at an edge where the first land row 22b is in contact with the circumferential groove 28b in the vicinity where the lug groove 34b of the first land row 22b communicates with the circumferential groove 28b. Yes. Similarly, a chamfer 40 is provided at an edge where the second land portion row 24b contacts the circumferential groove 28b in the vicinity where the lug groove 38b of the second land portion row 24b communicates with the circumferential groove 28b. The chamfer 40 is inclined in the tire width direction from the tire circumferential direction, and this inclination is preferably the same direction as the inclination direction of the bent portions of the sipes 33, 36b, 40b. By making the inclination direction the same direction, the wet performance can be exhibited stably and effectively.

  Note that, in the tire 10, the merging portion of the arcuate curved groove 32 with the circumferential groove 26a, the merging portion of the lug groove 30 with the circumferential groove 26b, and the circumferential grooves 26a and 28a, 26b and 28b of the lug grooves 34a and 34b. The pattern may be arranged so that the joining part with the circumferential direction grooves 28a and 28b of the lug grooves 38a and 38b do not exist at the same position in the tire circumferential direction. By configuring the patterns so that the merging portions do not exist at the same position in the tire circumferential direction, the level of pattern noise generated depending on the air flow generated at the merging portions can be reduced.

The groove width of the two circumferential grooves 26a and 26b sandwiching the tread center portion 20 is 10 to 50% of the length in the tire width direction of the tread center portion 20 sandwiched on both sides by the circumferential grooves 26a and 26b. Preferably there is.
Further, in the tire 10, sipes are provided in any of the tread center portion 20, the first land portion rows 22a and 22b, and the second land portion rows 24a and 24b, but the sipes may not be provided in part. However, it may not be provided at all.
In the first land portion rows 22a and 22b and the second land portion rows 24a and 24b, the groove depths of the lug grooves 34a, 34b, 38a, and 38b forming these block rows are partially shallow, and the lug grooves are partially It may be cut into pieces.
Moreover, it is preferable that the circumferential grooves 28a and 28b and the circumferential grooves 26a and 26b are provided in line-symmetric positions with the tire center CL as the center.

〔Example〕
In order to examine the effect of the tire 10 as described above, a tire was prototyped and examined.
The tire size is 215 / 60R16 for passenger car tires. The rim was 16 × 6.5J and the air pressure was 200 kPa. The tire structure was a radial structure with a 2-belt (steel belt) and a 2-ply turn-up structure. Using a sedan type passenger car, we investigated uneven wear resistance and wet performance.
The prototype tire with a pattern produced a pattern having the elements shown in Table 1 below.
Here, the groove depths of the circumferential grooves 26a, 26b, 28a, 28b were all 8.5 mm, and the groove widths were all 6.8 mm. The groove width and groove depth at the junction of the arcuate curved groove 32 and the adjacent arcuate curved part are 3.0 mm and 4.0 mm, and the groove width and groove depth of the arcuate curved groove 32 in the vicinity of the tire center CL are set. The thickness was 4.0 mm and 5.0 mm, and the groove width and depth at the junction of the arcuate curved groove 32 and the circumferential groove 26 a were 5.0 mm and 6.8 mm. The groove width and depth of the lug groove 30 at the junction with the circumferential groove 26b were 3.0 mm and 4.0 mm, and the length of the lug groove 30 was 8.0 mm. The groove depth and groove width of the lug grooves 34a, 34b, 38a, 38b were 6.8 mm and 5.0 mm. The narrow portion of the lug groove 34b has a groove width of 2.0 mm. The groove depths of the lug grooves 38a and 38b become shallower toward the shoulders.

Regarding the uneven wear resistance performance, the first land row 22a and 22b and the second land row 24a and 24b at the both ends in the tire circumferential direction after driving a passenger car for 6000 miles (about 10,000 km). The amount of wear was measured, and the difference in wear amount between both ends was determined and averaged.
On the other hand, with regard to wet performance, the vehicle was run on a wet road surface in a test course, and the handling performance on the wet road surface was examined by driver's sensory evaluation.
Table 2 below shows the results. In Table 2, the evaluation result of each tire was obtained as an index using the pattern F, which is a tire of a comparative example, as a reference (index 100). The larger the value of the index, the better the performance.

  From Table 2, it can be seen that the patterns A and B, which are examples of the present invention, are excellent in each performance with respect to the pattern F, and have both high wear resistance and wet performance at a high level. In addition, it can be seen that the pattern A improves the wet performance by 10 points or more with respect to the patterns C to F.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, this invention is not limited to the said embodiment, Of course, in the range which does not deviate from the main point of this invention, you may make a various improvement and change. is there.

(A) is a schematic perspective view of the pneumatic tire which is one Example of the pneumatic tire of this invention, (b) is a top view of the pattern provided in the tire shown to (a). It is a figure explaining the groove | channel cross-sectional shape of the arcuate curved groove | channel of the pneumatic tire shown in FIG. It is a figure explaining the chamfering of the arcuate curved groove | channel of the pneumatic tire shown in FIG. It is a figure which shows the pattern of one Example in the pneumatic tire of this invention. (A)-(d) is a figure which shows the pattern of the comparative example in the pneumatic tire of this invention.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread part 14 Pattern 20 Tread center part 22a, 22b 1st land part row | line | column 24a, 24b 2nd land part row | line | column 26a, 26b, 28a, 28b Circumferential groove | channel 30 Lug groove | channel 31, 33, 35, 36a, 36b, 37a, 40a, 40b, 41a Sipe 32 Arcuate curved groove 34a, 34b, 38a, 38b Lug groove

Claims (6)

A pneumatic tire having an asymmetric pattern with respect to a tire center, the vehicle inner side mounting and the vehicle outer side mounting defined for both sides of the tire,
When the pattern corresponding to the vehicle inner side with respect to the tire center is the inner pattern side, and the pattern corresponding to the vehicle volume outer side is defined as the outer pattern,
The inner pattern is provided with at least two circumferential grooves, and at least three inner land rows are formed by the two inner circumferential grooves and the ground contact end in the tire width direction.
Each of these inner land portion rows communicates at both ends with an inner circumferential groove in contact with the inner land portion row, an inner lug groove provided so as to cross the inner land portion row, or a grounding end in the tire width direction. At least one first sipe is provided;
The outer pattern is provided with at least one outer circumferential groove, and at least two outer land rows are formed by the outer circumferential groove and a ground contact end in the tire width direction,
Each of these outer land rows is connected to one end to an outer circumferential groove in contact with the outer land row, an outer lug groove that crosses the outer land row, or a grounding end in the tire width direction, and the other A second sipe that is closed without communicating with the outer circumferential groove, the outer lug groove, and the grounding end, and the second sipe is bent and closed in the vicinity of the other end. A pneumatic tire characterized by In the inner pattern, the total number of inner circumferential grooves where the first sipe is in contact with the inner land portion row, the inner lug grooves crossing the inner land portion row, or the open ends communicating with the grounding end in the tire width direction, When calculated for each inner land part row,
The total number in the inner land portion row closest to the ground contact edge is larger than the total number in the inner land portion row closest to the tire center,
When the total number is compared among all the adjacent inner land portion rows, the total number in the inner land portion row located on the grounding end side is the total number in the inner land portion row located on the tire center side. The pneumatic tire according to claim 1, wherein the pneumatic tire is larger than or equal to.   The pneumatic tire according to claim 1 or 2, wherein a length of a portion of the second sipe that is bent in the vicinity of the other end of the second sipe is 2 mm or more.   Of the second sipes, sipes provided in adjacent outer land rows across the circumferential groove of the outer pattern extend at least in the tire width direction, and the adjacent outer land rows in this sipe Ends positioned on the outer circumferential groove between the outer circumferential grooves are arranged so as to be bent and closed ends, or both are arranged so as to communicate with the outer circumferential grooves. The pneumatic tire according to any one of claims 1 to 3.   The extending direction of the bent portion in the vicinity of the other end of the second sipe is a direction inclined in the tire width direction from the tire circumferential direction, and the inclined direction of the bent portion is the entire second sipe. The pneumatic tire according to any one of claims 1 to 4, which is aligned. In the inner pattern,
The inner land portion row is provided with a third sipe that branches from the middle of the first sipe, and the third sipe that branches within the range of the contact width of the inner pattern extends in the tire width direction. The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire extends toward a ground contact end.

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