JP2019073129A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which secures a grounding property, rigidity balance in a tire circumferential direction, and drainage performance.SOLUTION: A pneumatic tire comprises first narrow grooves 30 on one side and second narrow grooves 40 on the other side, in a width direction of a main groove 20 extending straight in a tire circumferential direction. In the first narrow grooves 30 and the second narrow grooves 40, one end is open to the main groove 20 extending straight, whereas the other end is closed within land parts 24 and 26. The first narrow grooves 30 and the second narrow grooves 40 are bent in the same direction in the tire circumferential direction, and a portion 32 closer to the one end side of the first narrow groove 30 than a bent part 31, and a portion 42 closer to the one end side of the second narrow groove 40 than a bent part 41 are extended in the same direction. Further, a portion 43 closer to the other end side of the second narrow groove 40 than the bent part 41 is directed more in the tire circumferential direction compared to a portion 33 closer to the other end side in the first narrow groove 30 than the bent part 31.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a pneumatic tire.

  The narrow groove extending in the tire width direction is provided on both sides in the width direction of the main groove extending straight in the circumferential direction of the tire, and one end of the narrow groove is open to the main groove and the other end is closed in the land portion BACKGROUND A tire has been known conventionally (see, for example, Patent Document 1). Such narrow grooves divide the land portion on the side of the main groove in the tire circumferential direction, thereby improving the ground contactability of the land portion.

Patent No. 5781566

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

  Then, this invention makes it a subject to provide the pneumatic tire which ensured the grounding property, the rigidity balance of a tire circumferential direction, and drainage property.

  The pneumatic tire according to the embodiment includes the first narrow groove in one width direction of the main groove extending straight in the circumferential direction of the tire and the second narrow groove in the other, and the first narrow groove and the second narrow groove In the pneumatic tire having one end opened in the main groove extending straight and the other end closed in the land portion, the first narrow groove and the second narrow groove face in the same direction in the tire circumferential direction. It bends, and the part on the above-mentioned one end side from the bending part in the above-mentioned 1st narrow groove and the part on the above-mentioned one end side than the bending part in the above 2nd narrow groove incline in the same direction to the tire peripheral direction The portion on the other end side of the second narrow groove with respect to the bent portion is directed in the tire circumferential direction more than the portion on the other end side of the bent portion of the first narrow groove. Do.

  The pneumatic tire according to the embodiment has the above-described features to secure the contactability, the rigidity balance in the circumferential direction of the tire, and the drainage property.

BRIEF DESCRIPTION OF THE DRAWINGS Width direction sectional drawing of the pneumatic tire 1 of embodiment. Tread pattern of an embodiment. The figure which looked at the center main groove 10 from the tire radial outside (however, the 3rd narrow groove 28 was omitted for simplification). The figure which looked at the center main groove 10 from the tangent direction of the tire equator E (however, the 3rd narrow groove 28 was omitted for simplification). Sectional drawing of the center main groove 10 in the AA of FIG. The figure which looked at the 1st narrow slot 30 and the 2nd narrow slot 40 from the tire radial outside. (A) Sectional drawing of the slit part 32 of the 1st fine groove 30 in the BB line | wire of FIG. (B) Sectional drawing of the sipe part 33 of the 1st fine groove 30 in the CC line | wire of FIG. (A) Sectional drawing of the slit part 42 of the 2nd fine groove 40 in the DD line of FIG. (B) Sectional drawing of the sipe part 43 of the 2nd fine groove 40 in the EE line of FIG. The figure which looked at the shoulder rib 26 from the tire radial outside. Sectional drawing of the 4th fine groove 50 in the FF line of FIG. The figure which shows three-dimensional Sipe 55. FIG. (A) is the figure which looked at the 4th fine groove 50 from the tire surface. (B) is a figure which shows one wall surface of the 4th fine groove 50. FIG. (C) is sectional drawing of the 4th fine groove 50 in the surface parallel to the ground-contact plane in the position of the GG line | wire of (b).

  Embodiments will be described based on the drawings. In addition, the following embodiment is an illustration and the range of invention is not limited to this.

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

1. Cross-Sectional Structure of Pneumatic Tire 1 As illustrated in FIG. 1, bead portions 2 are provided on both sides in the tire width direction of the pneumatic tire 1. 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 radially outer side of the bead core 2a. A carcass ply 5 is bridged over 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 coated with rubber. The carcass ply 5 forms a skeletal 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 in the tire width direction around the bead portion 2 You Inside the carcass ply 5, a sheet-like inner liner 6 made of rubber having low permeability to air is attached.

  One or more belts 7 are provided on the radially outer side of the carcass ply 5. The belt 7 is a member made of a large number of steel cords coated with rubber. A tread rubber 3 having a contact surface with the road surface (hereinafter referred to as a “contact surface”) is provided on the outer side in the tire radial direction of the belt 7. Further, 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 belt lower pad and a chafer are provided according to the functional needs 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 end 22 are provided. In addition, a rib is a land part which follows a tire peripheral direction. Here, the land portion is a portion formed by being divided by a groove and having a ground contact surface. Further, the ground contact end 22 is the tire width direction end of the ground contact surface in a loaded state.

  Further, the first narrow groove 30 is provided on the tire equator E side of the shoulder main groove 20, and the second narrow 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. The narrow grooves 20, 30, 40, 50 are arranged at equal or substantially equal intervals in the tire circumferential direction. The structure of these thin grooves 20, 30, 40, 50 will be described later.

3. Structure of Main Groove As shown in FIGS. 2 to 4, the center main groove 10 extends in a zigzag in the tire circumferential direction. That is, the center main groove 10 has a zigzag shape as viewed from the outer side in the tire radial direction. More specifically, the center main groove 10 is a long groove portion 11 extending obliquely with respect to the tire circumferential direction, and a short groove portion inclined with respect to the tire circumferential direction and extending in a direction different from the long groove portion 11 It consists of 12 and. The center main groove 10 is formed by alternately arranging the long grooves 11 and the short grooves 12.

  As described above, since the center main groove 10 is in a zigzag shape, the convex portion 14 protruding into the center main groove 10 and the center main groove are formed at the boundary of the long groove portion 11 and the short groove portion 12 in the center main groove 10. A recessed portion 15 facing the convex portion 14 with 10 interposed therebetween is formed.

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

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

  As shown in FIGS. 3 to 5, tapered surfaces 16 are provided on both sides in the width direction of the center main groove 10. The tapered surface 16 is a surface which is continuous from the ground contact surface to the back side of the center main groove 10, and is a surface having a shape for chamfering the corner portion on the center main groove 10 side of the center rib 24 as shown in FIG. The tapered surface 16 widens the width of the open end of the center main groove 10 to the ground contact surface. Note that although the tapered surface 16 may reach the ground surface, as shown in FIG. 5, a wall 17 with a slight height (for example, about 0.5 mm) is formed between the tapered surface 16 and the ground surface. It may be 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 to the ground surface is, for example, 40 ° or more and 50 ° or less.

  As shown in FIG. 3, the width of the tapered surface 16 gradually widens from the position of the recess 15 of the center main groove 10 toward the position of the protrusion 14 on both sides in the width direction of the center main groove 10. As a result, the angle θ1 of the opening end of the center main groove 10 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.

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

  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 Narrow Grooves As shown in FIG. 2, the first narrow grooves 30 extend 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 closes in the center rib 24.

  The first narrow groove 30 is bent as viewed from the outer side in the tire radial direction. The bending portion 31 forms an obtuse angle. As shown in FIG. 6, a portion closer to the shoulder main groove 20 than the bending portion 31 of the first fine groove 30 is a slit portion 32 which is relatively wide. On the other hand, the portion on the tip end side of the bending portion 31 of the first narrow groove 30 is a narrow sipe portion 33. In the loaded state, the slit 32 does not close but the sipes 33 close. 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 location that is the inside (the side forming the obtuse angle) of the bending of the first narrow groove 30. The tapered surface 34 widens the width of the open end of the sipe portion 33 to the ground contact surface. The tapered surface 34 is a surface which is continuous from the ground surface to the back side of the sipe portion 33 in the vicinity of the ground surface. Although the tapered surface 34 may reach the ground surface, as shown in FIG. 7B, a wall of a slight height (for example, about 0.5 mm) between the tapered surface 34 and the ground surface. 35 may be formed. Further, the tapered surface 34 has not reached the bottom of the sipe portion 33. By providing the tapered surface 34, the width of the sipe portion 33 gradually widens as it approaches the ground contact surface. The angle of the tapered surface 34 with respect to the contact surface 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 bending portion 31, and is the widest at the bending 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 end 22. One end of the second narrow groove 40 is open to the shoulder main groove 20 and the other end is closed in the shoulder rib 26.

  The second narrow groove 40 is bent as viewed from the outer side in the tire radial direction. The bending portion 41 forms an obtuse angle. As shown in FIG. 6, a portion closer to the shoulder main groove 20 than the bending portion 41 of the second fine groove 40 is a slit 42 having a relatively large width. On the other hand, a portion on the tip end side of the bending portion 41 of the second fine groove 40 is a narrow sipe portion 43. In the loaded state, the slit portion 42 is not closed but the sipe portion 43 is closed. 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 FIG. 6 and FIG. 8, the sipe portion 43 has a tapered surface 44 at a location that is the inside (the side forming the obtuse angle) of the bending of the second narrow groove 40. The tapered surface 44 widens the width of the open end of the sipe portion 43 to the ground contact surface. The tapered surface 44 is a surface which is continuous from the ground contact surface to the back side of the sipe portion 43 in the vicinity of the ground contact surface. Although the tapered surface 44 may reach the ground contact surface, as shown in FIG. 8B, a wall of 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 widens as it approaches the ground contact surface. The angle of the tapered surface 44 with respect to the ground surface 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 bending portion 41, and is the widest at the bending 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 narrow groove 40 extend in the same direction with respect to the tire circumferential direction. Furthermore, the slit portion 32 of the first narrow groove 30 and the slit portion 42 of the second narrow groove 40 are on the same straight line.

  The first narrow groove 30 and the second narrow groove 40 are bent in the same direction in the tire circumferential direction. That is, the respective sipe portions 33, 43 extend from the bending portions 31, 41 of the respective thin grooves 30, 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 sub groove. The minor groove is a groove having a width smaller than that of the main groove, and is a groove which continuously makes a round 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 narrow groove 40 are respectively provided on both sides in the tire width direction. However, the first narrow groove 30 and the second narrow groove 40 are disposed in opposite directions in the tire circumferential direction on one side and the other side in the tire width direction. The first narrow groove 30 and the second narrow groove 40 are shifted in the tire circumferential direction on one side and the other side in the tire width direction. That is, the position of the first narrow groove 30 on one side in the tire width direction and the position of the first narrow groove 30 on the other side in the tire width direction do not match in the tire width direction, and one side in the tire width direction The position of the second narrow groove 40 on the side and the position of the second narrow groove 40 on the other side in the tire width direction do not completely coincide with each other in the tire width direction.

  Also, the third narrow groove 28 extends from the zig-zag center main groove 10 in the direction of the grounding end 22. One end of the third narrow groove 28 is open to the center main groove 10 and the other end is closed in the center rib 24. The third narrow groove 28 does not bend but extends in a straight shape.

  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 fine groove 28 has a tapered surface 29 which widens the width of the opening end to the ground contact surface. The tapered surface 29 is a surface which is continuous from the ground contact surface to the back side of the third narrow groove 28 in the vicinity of the ground contact surface. Note that although the tapered surface 29 may reach the ground surface, as in the case of the first fine groove 30, a wall of a slight height (for example, about 0.5 mm) between the tapered surface 29 and the ground surface. A part may be formed. 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 contact surface is, for example, 40 ° or more and 50 ° or less. The width of the tapered surface 29 gradually narrows in the direction from the center main groove 10 toward the ground end 22.

  Further, as shown in FIGS. 2 and 9, the fourth narrow groove 50 extends in the tire width direction in 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 outward from the ground contact end 22 in the tire width direction.

  The fourth narrow groove 50 is bent at a position on the one end side which is the tire equator E side when viewed from the outer side 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 from the one end to the ground end 22 in the tire width direction). The fourth narrow groove 50 is a position directed from the one end to the ground contact end 22 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 narrow groove 50 is formed as a sipe that closes in a loaded state. The width of the fourth narrow groove 50 is, for example, 0.7 mm or more and 0.9 mm or less. The depth of the fourth narrow groove 50 is gradually reduced from the bending portion 51 to the one end side.

  As shown in FIGS. 9 and 10, a tapered surface 54 is provided at the inside of the bend of the fourth fine groove 50. The tapered surface 54 widens the width of the open end of the fourth narrow groove 50 to the ground contact surface. The tapered surface 54 is a surface which is continuous from the ground contact surface to the back side of the fourth narrow groove 50 in the vicinity of the ground contact surface. Although the tapered surface 54 may reach the ground surface, as shown in FIG. 10, a wall 56 having a slight height (for example, about 0.5 mm) is formed between the tapered surface 54 and the ground surface. It may be done. 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 narrow groove 50 gradually widens as it approaches the ground contact surface. The angle of the tapered surface 54 with respect to the ground surface is, for example, 35 ° or more and 45 ° or less. The width of the tapered surface 54 gradually increases from the ground end 22 toward the bending portion 51, and is the widest at the bending portion 51. A tapered surface 54 is provided continuously from the bending portion 51 also at a position closer to the tire equator E than the bending portion 51 of the fourth narrow groove 50.

  A portion closer to the grounding end 22 than the bent portion 51 in the fourth narrow groove 50 is a three-dimensional sipes 55 as illustrated in FIG. The three-dimensional sipe 55 is a sipe whose shape changes in the depth direction. As shown in FIG. 11C, the three-dimensional sipe 55 according to the embodiment has a wavelike shape including peak portions 57 and valley portions 58 on a cross section in a plane parallel to the ground contact surface at a location deeper than the ground contact surface. It has become. And as shown in FIG.11 (b), the peak part 57 and the valley part 58 are extended in zigzag form in the depth direction of the three-dimensional sipe 55. As shown in FIG.

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

  As shown in FIG. 9, in the shoulder rib 26, in addition to the fourth narrow groove 50, the above-mentioned second narrow groove 40 exists. The fourth narrow groove 50 overlaps the sipe portion 43 of the second narrow 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 closed before the sipe portion 43 and does not communicate with the sipe portion 43.

5. Effects of the Embodiment In the pneumatic tire 1 of the embodiment, since the first narrow groove 30 is provided on one side in the width direction of the shoulder main groove 20 and the second narrow groove 40 is provided on the other side, the center rib 24 and the shoulder rib 26 are provided. Grounding is good. Furthermore, since the first fine groove 30 and the second fine groove 40 are bent, parts on both sides of the first fine groove 30 and the second fine groove 40 when a large stress is applied to the center rib 24 and the shoulder rib 26. The tire can mesh with each other in the tire width direction, and the lateral rigidity (the rigidity in the tire width direction) of the center rib 24 and the shoulder rib 26 is secured. Here, the lateral rigidity tends to decrease in the vicinity of the shoulder main groove 20 which extends straight in the circumferential direction of the tire, but the lateral rigidity in the vicinity of the shoulder main groove 20 is obtained by bending the first narrow groove 30 and the second narrow groove 40. It is complemented.

  In addition, the slit portion 32 of the first narrow groove 30 and the slit portion 42 of the second narrow groove 40 extend in the same direction with respect to the tire circumferential direction, and the first narrow groove 30 and the second narrow groove 40 The first narrow groove 30 and the second narrow groove 40 are arranged to be shifted in the tire circumferential direction because they are bent in the same direction in the tire circumferential direction. As a result, in the center rib 24 and the shoulder rib 26, not only lateral rigidity but also longitudinal rigidity (stiffness 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 do. 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 is relatively Extending facing, the sipe portion 33 of the first narrow groove 30 extends relatively in the tire width direction) has the effect of maintaining longitudinal rigidity in the shoulder rib 26 provided with the second narrow groove 40, The effect of making the ground contactability of the center rib 24 provided with the first narrow groove 30 better is also brought about.

  As described above, in the pneumatic tire 1 of the embodiment, the ground contactability, the rigidity balance in the circumferential direction of the tire, and the drainage property are secured. As a result, the performance such as the steering stability of the pneumatic tire 1 is secured.

  Here, even if the second narrow groove 40, which is a narrow groove in which the sipe portion is more directed in the tire circumferential direction, is provided in either the center rib 24 or the shoulder rib 26, the above effect can be obtained. Therefore, contrary to the embodiment, even if the first narrow groove 30 is provided in the shoulder rib 26 and the second narrow groove 40 is provided in the center rib 24, the above-described effect can be obtained.

  However, the rib on the ground contact end 22 side (i.e., the shoulder rib 26 in the present embodiment) greatly affects the braking performance. And drainage performance and longitudinal rigidity affect the performance of braking. Therefore, it is better for the braking performance to have the second narrow groove 40 effective for drainage and longitudinal rigidity in the shoulder rib 26 as in the present embodiment.

  Further, the rib on the tire equator E side (that is, the center rib 24 in the present embodiment) greatly affects the steering stability. And the ground contact affects the maneuverability. Therefore, providing the first narrow groove 30 that is more effective in grounding performance in the center rib 24 is better for handling.

  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 narrow groove 40 extend in the same direction with respect to the tire circumferential direction, and further the first narrow groove The 30 and the second narrow groove 40 are bent in the same direction in the tire circumferential direction. In addition to this, in the present embodiment, since the slit portion 32 of the first narrow groove 30 and the slit portion 42 of the second narrow groove 40 are on the same straight line, the first narrow groove 30 and the second narrow groove 40 Is reliably shifted 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 narrow groove 40, since the widths of the slit portions 32 and 42 on the side of the shoulder main groove 20 are wider than the bent portions 31 and 41, the grounding property is secured. Moreover, the rigidity is ensured by the part ahead of the bending parts 31 and 41 being the sipe parts 33 and 43 with a narrow width. Furthermore, by providing the sipe portions 33 and 43 with tapered surfaces, rigidity in the vicinity of the bent portions 31 and 41 is secured.

  Furthermore, the above-mentioned center main groove 10 secures the rigidity of the center rib 24 by being in a zigzag shape, and by providing the tapered surface 16 also ensures the drainage property. Therefore, the combination of the center main groove 10 and the first and second narrow grooves 30 and 40 ensures the rigidity and the drainage performance of the entire tire. Further, the fourth narrow groove 50 not only improves the contactability of the shoulder rib 26 but also ensures drainage by opening to the outside in the tire width direction. Therefore, the combination of the fourth narrow groove 50 and the first and second narrow grooves 30 and 40 secures the grounding property and the drainage property of the whole tire.

6. 5. Modifications Various omissions, substitutions, and alterations can be made to the above embodiment without departing from the scope of the invention.

  When the center main groove is not zigzag but extends straight in the tire circumferential direction as in the above embodiment, the first narrow groove 30 and the second narrow groove 40 may be provided in the center main groove .

  Further, in the first narrow groove and the second narrow groove, the portion on the main groove side from the bending portion is not limited to the slit portion having a relatively large width, and the portion on the tip side (closed end side) beyond the bending portion has a width Not limited to narrow sipes. For example, in the first narrow groove and the second narrow groove, the whole may be configured by a slit portion wider than the sipes 33 and 43 in the above embodiment.

E: tire equator, 1: pneumatic tire, 2: bead portion, 2a: bead core, 2b: bead filler, 3: tread rubber, 4: sidewall rubber, 5: carcass ply, 6: inner liner, 7: belt, DESCRIPTION OF SYMBOLS 10 ... Center main groove, 11 ... Long groove part, 12 ... Short groove part, 13 ... Groove bottom, 14 ... Convex part, 14a ... Right convex part, 14b ... Left convex part, 15 ... Concave part, 16 ... Tapered surface, 17 ... Wall portion, 20 ... Shoulder main groove, 22 ... Grounding end, 24 ... Center rib, 26 ... Shoulder rib, 28 ... Third narrow groove, 29 ... Tapered surface, 30 ... First narrow groove, 31 ... Bend, 32 ... Slit portion 33: Sipe portion 34: Tapered surface 35: Wall portion 40: Second narrow groove 41: Bent portion 42: Slit portion 43: Sipe portion 44: Tapered surface 45: Wall portion , 50 ... 4th narrow groove, 51 ... Curved portion, 54 ... tapered surface 55 ... three-dimensional sipes, 56 ... wall portion, 57 ... peak portion, 58 ... valley

Claims (4)

The first narrow groove is provided in one width direction of the main groove extending straight in the circumferential direction of the tire, and the second narrow groove is provided in the other, and the first narrow groove and the second narrow groove have one end extending straightly In a pneumatic tire which is open to the main groove and closed at the other end in the land portion,
The first narrow groove and the second narrow groove are bent in the same direction in the tire circumferential direction,
The portion on the one end side of the first thin groove than the bending portion and the portion on the one end side of the second thin groove are inclined in the same direction with respect to the tire circumferential direction.
A portion of the second narrow groove on the other end side with respect to the bent portion is characterized by being directed in the tire circumferential direction more than a portion of the first narrow groove on the other end side than the bent portion. , Pneumatic tires.   The pneumatic tire according to claim 1, wherein the first narrow groove is provided on the tire equator side and the second narrow groove is provided on the ground contact end side across the main groove extending straight.   The pneumatic according to claim 1 or 2, wherein the portion on the one end side of the bending portion in the first fine groove and the portion on the one end side of the bending portion in the second fine groove are on the same straight line. tire. In the first narrow groove and the second narrow groove, the portion on the other end side of the bending portion is a sipe that is narrower than the portion on the one end side than the bending portion, and the ground plane is located in the bending inner side of the sipe The pneumatic tire according to any one of claims 1 to 3, wherein a tapered surface is provided which widens the width of the open end thereof.

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