JP6949654B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Air in which narrow grooves extending in the tire width direction are provided on both sides of the main groove extending straight in the tire circumferential direction, one end of the fine groove opens in the main groove and the other end is closed in the land portion. Tires with tires have been conventionally known (see, for example, Patent Document 1). Since such a narrow groove divides the portion of the land portion on the main groove side in the tire circumferential direction, the ground contact property of the land portion is improved.

Japanese Patent No. 5781566

However, in the above-mentioned pneumatic tire, the rigidity of the land portion is not uniform in the tire circumferential direction because the rigidity is different between the place where the narrow groove is provided and the place other than that. Further, the narrow groove extending in the tire width direction has a small contribution to drainage.

Therefore, it is an object of the present invention to provide a pneumatic tire that secures ground contact property, rigidity balance in the tire circumferential direction, and drainage property.

The pneumatic tire of the embodiment is provided with a first narrow groove on one side in the width direction of a main groove extending straight in the tire circumferential direction and a second fine groove on the other, and the first fine groove and the second fine groove are In a pneumatic tire in which one end is opened in the main groove extending straight and the other end is closed in the land portion, the first narrow groove and the second fine groove are directed in the same direction in the tire circumferential direction. A straight line that is bent and the portion on the one end side of the bent portion in the first narrow groove and the portion on the one end side of the bent portion in the second narrow groove are inclined with respect to the tire circumferential direction. Riding on the tire, the portion on the other end side of the bent portion in the second narrow groove faces the tire circumferential direction from the portion on the other end side of the bent portion in the first narrow groove, and the first It is characterized in that the bent portion of the 1 fine groove and the bent portion of the second fine groove form an blunt angle.

The pneumatic tire of the embodiment has the above-mentioned characteristics, so that the ground contact property, the rigidity balance in the tire circumferential direction, and the drainage property are ensured.

FIG. 3 is a cross-sectional view in the width direction of the pneumatic tire 1 of the embodiment. The tread pattern of the embodiment. The view of the center main groove 10 seen from the outside in the tire radial direction (however, the third narrow groove 28 is omitted for simplification). The center main groove 10 is seen from the tangential direction of the tire equator E (however, the third narrow groove 28 is omitted for simplification). FIG. 3 is a cross-sectional view of the center main groove 10 along the line AA of FIG. The figure which looked at the 1st groove 30 and the 2nd groove 40 from the outside in the tire radial direction. (A) A cross-sectional view of the slit portion 32 of the first narrow groove 30 along the line BB of FIG. (B) Cross-sectional view of the sipe portion 33 of the first narrow groove 30 along the CC line of FIG. (A) A cross-sectional view of the slit portion 42 of the second narrow groove 40 along the DD line of FIG. (B) FIG. 6 is a cross-sectional view of a sipe portion 43 of the second narrow groove 40 along the line EE of FIG. The figure which looked at the shoulder rib 26 from the outside in the tire radial direction. FIG. 9 is a cross-sectional view of the fourth narrow groove 50 along the FF line of FIG. The figure which shows the 3D sipe 55. (A) is a view of the fourth fine groove 50 as viewed from the tire surface. (B) is a diagram showing one wall surface of the fourth narrow groove 50. (C) is a cross-sectional view of the fourth narrow groove 50 on a plane parallel to the ground plane at the position of the GG line in (b).

The embodiment will be described with reference to the drawings. The following embodiments are examples, and the scope of the invention is not limited thereto.

In the following description, the width of the groove and the tapered surface provided in the groove is the length in the plane parallel to the tire contact patch in the direction orthogonal to the extension direction of the center line of the groove bottom of the groove. Is. Further, the load state is a state in which the pneumatic tire is rim-assembled on the regular rim to obtain the regular internal pressure and the regular load is applied. Here, the regular rim is a standard rim defined in standards such as JATMA, TRA, and ETRTO. The normal load is the maximum load defined in the above standard. The normal internal pressure is the internal pressure corresponding to the maximum load.

1. 1. Cross-sectional structure of the pneumatic tire 1 As illustrated in FIG. 1, bead portions 2 are provided on both sides of the pneumatic tire 1 in the tire width direction. The bead portion 2 is composed of a bead core 2a made of a steel wire wound in a circular shape and a rubber bead filler 2b provided on the radial outer side of the bead core 2a. Carcass ply 5 is bridged to the bead portions 2 on both sides in the tire width direction. The carcass ply 5 is a sheet-like member in which a large number of ply cords arranged in a direction orthogonal to the tire circumferential direction are covered with rubber. The carcass ply 5 forms the skeleton shape of the pneumatic tire 1 between the bead portions 2 on both sides in the tire width direction, and wraps the bead portion 2 by being folded back from the inside to the outside in the tire width direction around the bead portion 2. I'm tired. A sheet-shaped inner liner 6 made of rubber having low air permeability is attached to the inside of the carcass ply 5.

One or a plurality of belts 7 are provided on the outer side of the carcass ply 5 in the tire radial direction. The belt 7 is a member made of a large number of steel cords coated with rubber. A tread rubber 3 having a contact patch with the road surface (hereinafter referred to as a "contact patch") is provided on the outer side of the belt 7 in the tire radial direction. In addition, sidewall rubbers 4 are provided on both sides of the carcass ply 5 in the tire width direction. In addition to these members, members such as a pad under the belt and a checker are provided as required for the function of the pneumatic tire 1.

2. Outline of Tread Pattern The tread pattern illustrated in FIG. 2 is formed on the surface of the tread rubber 3. The tread pattern is provided with a center main groove 10 at the center in the tire width direction and shoulder main grooves 20 on both sides in the tire width direction as main grooves that are wide grooves extending in the tire circumferential direction. A center rib 24 sandwiched between the center main groove 10 and the shoulder main groove 20 and a shoulder rib 26 sandwiched between the shoulder main groove 20 and the ground contact end 22 are provided. The rib is a land portion that is continuous in the tire circumferential direction. Here, the land portion is a portion formed by being partitioned by a groove and has a ground contact surface. The ground contact end 22 is an end portion of the ground contact surface in the tire width direction under load.

Further, a first narrow groove 30 is provided on the tire equator E side of the shoulder main groove 20, and a second fine groove 40 is provided on the ground contact end 22 side of the shoulder main groove 20. Further, third narrow grooves 28 are provided on both sides of the center main groove 10 in the width direction. Further, the shoulder rib 26 is provided with a fourth narrow groove 50. These narrow grooves 20, 30, 40, and 50 are arranged at equal intervals or substantially equal intervals in the tire circumferential direction, respectively. The structures of these fine grooves 20, 30, 40 and 50 will be described later.

3. 3. Structure of main groove As shown in FIGS. 2 to 4, the center main groove 10 extends in a zigzag shape in the tire circumferential direction. That is, the center main groove 10 has a zigzag shape when viewed from the outside in the tire radial direction. More specifically, the center main groove 10 has a long groove portion 11 extending in an inclined direction with respect to the tire circumferential direction and a short groove portion extending in a direction different from the long groove portion 11 inclining with respect to the tire circumferential direction. It consists of twelve. The center main groove 10 is formed by alternately arranging long groove portions 11 and short groove portions 12.

Since the center main groove 10 has a zigzag shape in this way, the convex portion 14 protruding into the center main groove 10 and the center main groove are located at the boundary between the long groove portion 11 and the short groove portion 12 in the center main groove 10. A concave portion 15 facing the convex portion 14 with the 10 interposed therebetween is formed.

In the present embodiment, as shown in FIG. 4, the convex portion 14a on the right side and the convex portion 14b on the left side do not overlap with each other in the tire circumferential direction with respect to the center line of the center main groove 10, and the convex portion 14a on the right side does not overlap. There is a gap L in the tire width direction between and the convex portion 14b on the left side. The presence or absence of the gap L shall be determined at the groove bottom 13.

However, the top of the protrusion of the convex portion 14a on the right side into the groove and the top of the protrusion of the convex portion 14b on the left side into the groove are at the same position in the tire width direction, and these tops are one in the tire circumferential direction. They may be lined up on a circle. Further, the convex portion 14a on the right side and the convex portion 14b on the left side may overlap in the tire circumferential direction (in other words, the convex portion 14a on the right side and the convex portion 14b on the left side when viewed from the tire circumferential direction). May overlap).

As shown in FIGS. 3 to 5, tapered surfaces 16 are provided on both sides of the center main groove 10 in the width direction. The tapered surface 16 is a surface that is continuous from the ground contact surface to the inner side of the center main groove 10, and is a surface that chamfers the corner portion of the center rib 24 on the center main groove 10 side as shown in FIG. The tapered surface 16 widens the width of the opening end of the center main groove 10 to the ground plane. The tapered surface 16 may reach the ground contact surface, but as shown in FIG. 5, a wall portion 17 having a slight height (for example, about 0.5 mm) is formed between the tapered surface 16 and the ground contact surface. It may have been done. In the portion where the tapered surface 16 is provided, the width of the center main groove 10 gradually widens as it approaches the ground contact surface. The angle of the tapered surface 16 with respect to the ground plane is, for example, 40 ° or more and 50 ° or less.

Further, as shown in FIG. 3, the width of the tapered surface 16 gradually increases from the position of the concave portion 15 of the center main groove 10 toward the position of the convex portion 14 on both sides of the center main groove 10 in the width direction. As a result, the angle θ1 of the opening end of the center main groove 10 with respect to the ground contact surface with respect to the tire circumferential direction is smaller than the angle θ2 of the groove bottom 13 of the center main groove 10 with respect to the tire circumferential direction.

Further, the wider the tapered surface 16, the deeper the tapered surface 16 toward the groove bottom 13. Therefore, the depth of the tapered surface 16 gradually increases from the position of the concave portion 15 of the center main groove 10 toward the position of the convex portion 14. The depth of the tapered surface 16 at the deepest position is, for example, half the depth of the center main groove 10 to the groove bottom 13.

In the present embodiment, the tapered surface 16 as described above is provided in both the long groove portion 11 and the short groove portion 12.

On the other hand, the shoulder main groove 20 does not have a zigzag shape, but extends straight in the tire circumferential direction.

4. Structure of the narrow groove As shown in FIG. 2, the first fine groove 30 extends from the straight shoulder main groove 20 in the direction of the tire equator E. One end of the first narrow groove 30 opens into the shoulder main groove 20, and the other end is closed in the center rib 24.

The first narrow groove 30 is bent when viewed from the outside in the tire radial direction. The bent portion 31 forms an obtuse angle. As shown in FIG. 6, the portion of the first narrow groove 30 on the shoulder main groove 20 side of the bent portion 31 is a slit portion 32 having a relatively wide width. On the other hand, the portion of the first narrow groove 30 on the tip side of the bent portion 31 is a narrow sipe portion 33. The slit portion 32 does not close but the sipe portion 33 closes under load. The width of the slit portion 32 is, for example, 1.9 mm or more and 2.1 mm or less, and the width of the sipe portion 33 is, for example, 0.7 mm or more and 0.9 mm or less.

As shown in FIGS. 6 and 7, the sipe portion 33 has a tapered surface 34 at a position inside the bending of the first narrow groove 30 (the side forming an obtuse angle). The tapered surface 34 widens the width of the opening end of the sipe portion 33 to the ground plane. The tapered surface 34 is a surface that is continuous from the ground contact surface to the inner side of the sipe portion 33 in the vicinity of the ground contact surface. The tapered surface 34 may reach the ground contact surface, but as shown in FIG. 7B, a wall portion having a slight height (for example, about 0.5 mm) between the tapered surface 34 and the ground contact surface. 35 may be formed. Further, the tapered surface 34 does not reach the bottom of the sipe portion 33. By providing the tapered surface 34, the width of the sipe portion 33 gradually increases as it approaches the ground contact surface. The angle of the tapered surface 34 with respect to the ground plane is, for example, 40 ° or more and 50 ° or less. The width of the tapered surface 34 gradually increases from the tip of the first narrow groove 30 toward the bent portion 31, and is the widest at the bent portion 31. As shown in FIG. 7A, such a tapered surface is not provided in the slit portion 32. Therefore, the tapered surface 34 is provided only in the sipe portion 33 of the first narrow groove 30.

Further, as shown in FIG. 2, the second narrow groove 40 extends from the straight shoulder main groove 20 toward the ground contact end 22. One end of the second narrow groove 40 is opened in the shoulder main groove 20, and the other end is closed in the shoulder rib 26.

The second narrow groove 40 is bent when viewed from the outside in the tire radial direction. The bent portion 41 forms an obtuse angle. As shown in FIG. 6, the portion of the second narrow groove 40 on the shoulder main groove 20 side of the bent portion 41 is a slit portion 42 having a relatively wide width. On the other hand, the portion of the second narrow groove 40 on the tip side of the bent portion 41 is a narrow sipe portion 43. The slit portion 42 does not close but the sipe portion 43 closes under load. The width of the slit portion 42 is, for example, 1.9 mm or more and 2.1 mm or less, and the width of the sipe portion 43 is, for example, 0.7 mm or more and 0.9 mm or less.

As shown in FIGS. 6 and 8, the sipe portion 43 has a tapered surface 44 at a position inside the bending of the second narrow groove 40 (the side forming an obtuse angle). The tapered surface 44 widens the width of the opening end of the sipe portion 43 to the ground plane. The tapered surface 44 is a surface that is continuous from the ground contact surface to the inner side of the sipe portion 43 in the vicinity of the ground contact surface. The tapered surface 44 may reach the ground contact surface, but as shown in FIG. 8 (b), a wall portion having a slight height (for example, about 0.5 mm) between the tapered surface 44 and the ground contact surface. 45 may be formed. Further, the tapered surface 44 does not reach the bottom of the sipe portion 43. By providing the tapered surface 44, the width of the sipe portion 43 gradually increases as it approaches the ground contact surface. The angle of the tapered surface 44 with respect to the ground plane is, for example, 40 ° or more and 50 ° or less. The width of the tapered surface 44 gradually increases from the tip of the second narrow groove 40 toward the bent portion 41, and is the widest at the bent portion 41. Such a tapered surface is not provided in the slit portion 42. Therefore, the tapered surface 44 is provided only in the sipe portion 33 of the first narrow groove 30.

As shown in FIG. 6, the slit portion 32 of the first narrow groove 30 and the slit portion 42 of the second fine groove 40 extend in the same direction with respect to the tire circumferential direction. Further, the slit portion 32 of the first narrow groove 30 and the slit portion 42 of the second fine groove 40 are on the same straight line.

Further, the first narrow groove 30 and the second fine groove 40 are bent in the same direction in the tire circumferential direction. That is, the sipe portions 33 and 43 extend from the bent portions 31 and 41 of the narrow grooves 30 and 40 in the same direction in the tire circumferential direction. Further, the sipe portion 43 of the second narrow groove 40 faces the tire circumferential direction more than the sipe portion 33 of the first narrow groove 30. That is, the sipe portion 43 of the second narrow groove 40 has a smaller inclination angle with respect to the tire circumferential direction than the sipe portion 33 of the first narrow groove 30. The sipe portion 43 is a kind of auxiliary groove. The sub-groove is a groove narrower than the main groove, and is a groove that makes one continuous rotation in the tire circumferential direction or intermittently extends in the tire circumferential direction like the sipe portion 43. ..

As shown in FIG. 2, the first narrow groove 30 and the second fine groove 40 are provided on both sides in the tire width direction, respectively. However, the first narrow groove 30 and the second fine groove 40 are arranged on one side and the other side in the tire width direction in opposite directions in the tire circumferential direction. Further, the first narrow groove 30 and the second fine groove 40 are deviated in the tire circumferential direction on one side and the other side in the tire width direction. That is, the position of the first fine groove 30 on one side in the tire width direction and the position of the first fine groove 30 on the other side in the tire width direction do not match in the tire width direction, and one in the tire width direction. The position of the second groove 40 on the side and the position of the second groove 40 on the other side in the tire width direction do not completely match in the tire width direction.

Further, the third narrow groove 28 extends from the zigzag-shaped center main groove 10 toward the ground contact end 22. One end of the third narrow groove 28 opens into the center main groove 10, and the other end is closed in the center rib 24. The third narrow groove 28 does not bend and extends straight.

The third narrow groove 28 has a width similar to that of the slit portions 32 and 42 described above. Further, as shown in FIG. 2, the third narrow groove 28 has a tapered surface 29 that widens the width of the opening end to the ground contact surface. The tapered surface 29 is a surface that is continuous from the ground contact surface to the inner side of the third narrow groove 28 in the vicinity of the ground contact surface. The tapered surface 29 may reach the ground contact surface, but as in the case of the first fine groove 30, a wall having a slight height (for example, about 0.5 mm) between the tapered surface 29 and the ground contact surface. The portion may be formed. Further, the tapered surface 29 does not reach the bottom of the third narrow groove 28. By providing the tapered surface 29, the width of the third narrow groove 28 gradually widens as it approaches the ground contact surface. The angle of the tapered surface 29 with respect to the ground plane is, for example, 40 ° or more and 50 ° or less. The width of the tapered surface 29 gradually narrows from the center main groove 10 toward the ground contact end 22.

Further, as shown in FIGS. 2 and 9, the fourth fine groove 50 extends in the tire width direction at the shoulder rib 26. One end of the fourth narrow groove 50 is closed in the shoulder rib 26, and the other end is opened from the ground contact end 22 to the outside in the tire width direction.

The fourth narrow groove 50 is bent at a position on the one end side on the tire equator E side when viewed from the outside in the tire radial direction. The specific position of the bent portion 51 is, for example, only a length within 1/4 of the length of the fourth narrow groove 50 in the tire width direction (the length in the tire width direction from the one end to the ground contact end 22). , It is a position toward the ground contact end 22 side from the one end of the fourth narrow groove 50 in the tire width direction. The bent portion 51 forms an obtuse angle of, for example, 140 ° or more and 160 ° or less.

As shown in FIG. 10, the fourth groove 50 is formed as a sipe that closes under load. The width of the fourth fine groove 50 is, for example, 0.7 mm or more and 0.9 mm or less. The depth of the fourth fine groove 50 gradually becomes shallower from the bent portion 51 to the one end side.

As shown in FIGS. 9 and 10, a tapered surface 54 is provided at a position inside the bending of the fourth narrow groove 50. The tapered surface 54 widens the width of the opening end of the fourth narrow groove 50 to the ground plane. The tapered surface 54 is a surface that is continuous from the ground contact surface to the inner side of the fourth narrow groove 50 in the vicinity of the ground contact surface. The tapered surface 54 may reach the ground contact surface, but as shown in FIG. 10, a wall portion 56 having a slight height (for example, about 0.5 mm) is formed between the tapered surface 54 and the ground contact surface. It may have been done. Further, the tapered surface 54 does not reach the bottom of the fourth narrow groove 50. By providing the tapered surface 54, the width of the fourth fine groove 50 gradually widens as it approaches the ground contact surface. The angle of the tapered surface 54 with respect to the ground plane is, for example, 35 ° or more and 45 ° or less. The width of the tapered surface 54 gradually increases from the ground contact end 22 toward the bent portion 51, and is the widest at the bent portion 51. A tapered surface 54 is provided continuously from the bent portion 51 at a position on the tire equator E side of the bent portion 51 of the fourth narrow groove 50.

The portion of the fourth narrow groove 50 on the ground contact end 22 side of the bent portion 51 is a three-dimensional sipe 55 as illustrated in FIG. The three-dimensional sipe 55 is a sipe whose shape changes in the depth direction. As shown in FIG. 11 (c), the three-dimensional sipe 55 of the embodiment has a wavy shape consisting of a mountain portion 57 and a valley portion 58 on a cross section in a plane parallel to the ground plane at a place deeper than the ground plane. It has become. Then, as shown in FIG. 11B, the mountain portion 57 and the valley portion 58 extend in a zigzag shape in the depth direction of the three-dimensional sipe 55.

As shown in FIG. 2, the fourth narrow groove 50 is provided on both sides in the tire width direction. The fourth narrow groove 50 is arranged on both sides in the tire width direction in opposite directions in the tire circumferential direction. However, the fourth narrow groove 50 may be provided only on either one side in the tire width direction, and in that case, it is desirable that the fourth narrow groove 50 is provided on the OUT side (outside the vehicle) when the vehicle is mounted.

As shown in FIG. 9, the second narrow groove 40 is present in the shoulder rib 26 in addition to the fourth fine groove 50. The fourth narrow groove 50 has an overlap with the sipe portion 43 of the second fine groove 40 in the tire width direction. The one end of the fourth narrow groove 50 is close to the sipe portion 43 of the second narrow groove 40, but is blocked in front of the sipe portion 43 and does not communicate with the sipe portion 43.

5. Effect of the Embodiment In the pneumatic tire 1 of the embodiment, since the first narrow groove 30 is provided on one side of the shoulder main groove 20 in the width direction and the second fine groove 40 is provided on the other side, the center rib 24 and the shoulder rib 26 are provided. Good grounding property. Further, since the first narrow groove 30 and the second fine groove 40 are bent, both sides of the first fine groove 30 and the second fine groove 40 are formed when a large stress is applied to the center rib 24 and the shoulder rib 26. They can mesh with each other in the tire width direction, and the lateral rigidity (rigidity in the tire width direction) of the center rib 24 and the shoulder rib 26 is ensured. Here, the lateral rigidity tends to decrease in the vicinity of the shoulder main groove 20 extending straight in the tire circumferential direction, but the lateral rigidity in the vicinity of the shoulder main groove 20 is increased by bending the first narrow groove 30 and the second fine groove 40. It is complemented.

Further, the slit portion 32 of the first fine groove 30 and the slit portion 42 of the second fine groove 40 are inclined and extend in the same direction with respect to the tire circumferential direction, and the first fine groove 30 and the second fine groove 40 are further formed. Since the tires are bent in the same direction in the tire circumferential direction, the first narrow groove 30 and the second fine groove 40 are arranged so as to be offset in the tire circumferential direction. As a result, in the center rib 24 and the shoulder rib 26, not only the lateral rigidity but also the vertical rigidity (rigidity in the tire circumferential direction) is made uniform in the tire circumferential direction.

Further, since the sipe portion 43 of the second narrow groove 40 faces the tire circumferential direction more than the sipe portion 33 of the first narrow groove 30, the shoulder rib 26 provided with the second narrow groove 40 drains water in the tire circumferential direction. It is easy to be done. The sipe portion 43 of the second narrow groove 40 faces the tire circumferential direction more than the sipe portion 33 of the first narrow groove 30 (that is, the sipe portion 43 of the second narrow groove 40 faces the tire circumferential direction relatively. The fact that the sipe portion 33 of the first narrow groove 30 extends toward the tire width direction) has the effect of maintaining vertical rigidity in the shoulder rib 26 provided with the second fine groove 40, and It also has the effect of improving the ground contact property of the center rib 24 provided with the first narrow groove 30.

As described above, in the pneumatic tire 1 of the embodiment, the ground contact property, the rigidity balance in the tire circumferential direction, and the drainage property are ensured. As a result, performance such as maneuverability of the pneumatic tire 1 is ensured.

Here, the above effect can be obtained regardless of whether the center rib 24 or the shoulder rib 26 is provided with the second fine groove 40, which is a fine groove in which the sipe portion faces the tire circumferential direction. Therefore, contrary to the embodiment, even if the first fine groove 30 is provided in the shoulder rib 26 and the second fine groove 40 is provided in the center rib 24, the above effect can be obtained.

However, the rib on the ground contact end 22 side (that is, the shoulder rib 26 in the present embodiment) greatly affects the braking performance. Drainage and vertical rigidity affect braking performance. Therefore, it is better for braking performance that the second narrow groove 40, which is effective for drainage and vertical rigidity, is provided on the shoulder rib 26 as in the present embodiment.

Further, the rib on the equator E side of the tire (that is, the center rib 24 in the present embodiment) greatly affects the maneuverability. And the ground contact property affects the maneuverability. Therefore, it is better to provide the center rib 24 with the first fine groove 30, which is more effective for ground contact, for better maneuverability.

Further, as described above, in the present embodiment, the slit portion 32 of the first narrow groove 30 and the slit portion 42 of the second fine groove 40 extend in the same direction with respect to the tire circumferential direction, and further extend the first fine groove. The 30 and the second narrow groove 40 are bent in the same direction in the tire circumferential direction. In addition to that, in the present embodiment, since the slit portion 32 of the first narrow groove 30 and the slit portion 42 of the second fine groove 40 are on the same straight line, the first fine groove 30 and the second fine groove 40 Will surely shift in the tire circumferential direction. Therefore, the rigidity of the center rib 24 and the shoulder rib 26 in the vicinity of the shoulder main groove 20 is made uniform in the tire circumferential direction.

Further, in the first narrow groove 30 and the second fine groove 40, the width of the slit portions 32 and 42 on the shoulder main groove 20 side is wider than that of the bent portions 31 and 41, so that the ground contact property is ensured. Further, the rigidity is ensured by the sipe portions 33 and 43 having a narrow width beyond the bent portions 31 and 41. Further, since the sipe portions 33 and 43 are provided with tapered surfaces, the rigidity in the vicinity of the bent portions 31 and 41 is ensured.

Further, the center main groove 10 has a zigzag shape to ensure the rigidity of the center rib 24, and has a tapered surface 16 to ensure drainage. Therefore, the rigidity and drainage of the tire as a whole are ensured by the combination of the center main groove 10 and the first and second fine grooves 30 and 40. Further, the fourth narrow groove 50 not only improves the ground contact property of the shoulder rib 26, but also secures drainage property by opening outward in the tire width direction. Therefore, the combination of the fourth fine groove 50 and the first and second fine grooves 30 and 40 ensures the ground contact property and drainage property of the tire as a whole.

6. Modification Example Various omissions, substitutions, and modifications can be made to the above-described embodiment without departing from the gist of the invention.

When the center main groove extends straight in the tire circumferential direction instead of the zigzag shape as in the above embodiment, the first narrow groove 30 and the second fine groove 40 may be provided in the center main groove. ..

Further, in the first narrow groove and the second fine groove, the portion on the main groove side of the bent portion is not limited to the slit portion having a relatively wide width, and the portion ahead of the bent portion (closed end side) has a width. It is not limited to a narrow sipe part. For example, the first narrow groove and the second fine groove may be entirely composed of slit portions wider than the sipe portions 33 and 43 of the above embodiment.

E ... Tire equatorial line, 1 ... Pneumatic tire, 2 ... Bead part, 2a ... Bead core, 2b ... Bead filler, 3 ... Tread rubber, 4 ... Side wall rubber, 5 ... Carcass ply, 6 ... Inner liner, 7 ... Belt, 10 ... Center main groove, 11 ... Long groove, 12 ... Short groove, 13 ... Groove bottom, 14 ... Convex, 14a ... Right convex, 14b ... Left convex, 15 ... Concave, 16 ... Tapered surface, 17 ... wall part, 20 ... shoulder main groove, 22 ... grounding end, 24 ... center rib, 26 ... shoulder rib, 28 ... third narrow groove, 29 ... tapered surface, 30 ... first fine groove, 31 ... bent part, 32 ... Slit part, 33 ... Sipe part, 34 ... Tapered surface, 35 ... Wall part, 40 ... Second narrow groove, 41 ... Bending part, 42 ... Slit part, 43 ... Sipe part, 44 ... Tapered surface, 45 ... Wall part , 50 ... 4th narrow groove, 51 ... bent part, 54 ... tapered surface, 55 ... 3D sipe, 56 ... wall part, 57 ... mountain part, 58 ... valley part

Claims (3)

A first narrow groove is provided on one side in the width direction of a main groove extending straight in the tire circumferential direction, and a second fine groove is provided on the other. In a pneumatic tire that opens in the main groove and the other end is closed in the land
The first narrow groove and the second fine groove are bent in the same direction in the tire circumferential direction, and the tires are bent in the same direction.
The portion on one end side of the bent portion in the first narrow groove and the portion on the one end side of the bent portion in the second narrow groove ride on one straight line inclined with respect to the tire circumferential direction. ,
The portion of the second narrow groove on the other end side of the bent portion faces the tire circumferential direction from the portion of the first narrow groove on the other end side of the bent portion.
A pneumatic tire, characterized in that the bent portion of the first narrow groove and the bent portion of the second fine groove form an obtuse angle. The pneumatic tire according to claim 1, wherein the first narrow groove is provided on the equator side of the tire and the second fine groove is provided on the ground contact end side across the main groove extending in a straight shape. In the first narrow groove and the second fine groove, the portion on the other end side of the bent portion is a sipe narrower than the portion on the one end side of the bent portion, and the ground contact surface is located on the inside of the bend in the sipe. The pneumatic tire according to claim 1 or 2 , provided with a tapered surface that widens the width of the open end to the tire.

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