JP2019093907A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire in which a stone drilling resistance of a groove can be improved.SOLUTION: This pneumatic tire comprises: a circumferential groove 21 which is formed on a tread surface 3, and extends in a tire circumferential direction; and a width direction groove 22 which is formed on the tread surface 3, extends in a tire width direction, and crosses the circumferential groove 21. At least one groove 10 of the circumferential groove 21 and the width direction groove 22 is so formed that a groove wall 11 has a bent part 14, and a groove width on a groove bottom 12 side with respect to the bent part 14 is narrower than a groove width of an opening 13 of the groove 10, and a projection part 30, which projects from the groove bottom 12, is provided at an intersection part 25 of the circumferential groove 21 and the width direction groove 22.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a pneumatic tire.

  In the pneumatic tire, a groove is formed on the tread surface mainly to ensure drainage, but when the vehicle travels, a stone or the like may enter the groove and the groove may bite the stone. When the groove bites a stone, rolling of the pneumatic tire during traveling of the vehicle may cause so-called stone drilling in which the stone bites into the groove bottom of the groove and damages the groove bottom. In particular, in heavy-duty pneumatic tires mounted on vehicles that travel on and off road, stone drilling occurs when the stone caught by the groove bites into the bottom of the groove on road during off road travel. It will be easier. For this reason, some conventional pneumatic tires are intended to suppress stone biting in grooves. For example, in Patent Document 1, projections are provided at intersections where circumferential grooves and width direction grooves intersect in a fork shape, thereby reducing air column resonance and maintaining drainage, and suppressing stone bites. It is compatible.

JP, 2010-52698, A

  Here, as a method of reducing stone biting of the groove and suppressing stone drilling, the groove width on the groove bottom side of the groove opening by bending the groove wall at a predetermined position in the groove depth direction It is conceivable to make the width of the groove narrow and prevent the stone from getting into the bottom of the groove. However, even when the groove width on the groove bottom side is narrower than the groove width of the opening, at the intersection where the grooves cross each other, the narrow portions of the groove width also cross each other at the groove bottom side As a result, the portion on the groove bottom side where the groove width is narrow is also formed as a large area in plan view of the groove. For this reason, since stones easily enter the intersections between the grooves, at the intersections, the effect of suppressing the stone biting by reducing the groove width on the groove bottom side is reduced and the stones are easily bitten and bitten. There is a possibility that the invaginated stone reaches the bottom of the groove and stone drilling may occur. As described above, it has been very difficult to suppress the stone drilling of the entire groove including the intersection of the grooves.

  This invention is made in view of the above, Comprising: It aims at providing the pneumatic tire which can improve the stone drilling resistance of a groove.

  In order to solve the problems described above and achieve the object, the pneumatic tire according to the present invention is formed on a tread surface, and is formed on a circumferential groove extending in the circumferential direction of the tire and on the tread surface in the tire width direction And a width direction groove intersecting with the circumferential direction groove, and at least one of the circumferential direction groove and the width direction groove has a groove wall having a bent portion, and The groove width on the groove bottom side of the bent portion is smaller than the groove width of the opening of the groove, and a protrusion protruding from the groove bottom at the intersection between the circumferential groove and the width direction groove Are provided.

  In the pneumatic tire, it is preferable that the circumferential groove and the width direction groove have the same groove depth.

In the pneumatic tire, the projection is the shortest with the groove wall at a position within the range of 0% to 30% of the height of the projection from the tip of the projection toward the groove bottom side. distance d ₂ is, with respect to the groove width d ₁ at the position of the bent portion of the groove having the bent portion, it is preferable to have at least one place a portion to be the 1.2d ₁ ≧ d _2.

In the pneumatic tire, the protrusions shortest distance d ₂ and all of the groove walls facing the protrusion, with respect to the groove width d ₁ at the position of the bent portion, 0 <(d ₂ It is preferable to form in the range of / d ₁ ) ≦ 1.5.

In the pneumatic tire, the protrusion has a height H ₁ from the groove bottom, with respect to the groove depth H ₀ from the bent portion of the groove having the bent portion to the groove bottom, 0. It is preferable to be within the range of 03 ≦ (H ₁ / H ₀ ) ≦ 2.0.

In the pneumatic tire, the protrusion has a height H ₁ from the groove bottom, with respect to the groove depth Hg from the opening at the position of the intersection portion to the groove bottom, 0.1 ≦ It is preferable to be in the range of (H ₁ /Hg)≦0.4.

In the pneumatic tire, the groove having the bent portion, and the groove width W ₁ of the opening, the relationship between the groove width W ₂ at 1/2 position of the groove depth, 0 <(W ₂ It is preferable to be in the range of / W ₁ ) ≦ 0.5.

  In the pneumatic tire, preferably, the bent portion is positioned in a range of 30% to 60% of a groove depth from the groove bottom toward the opening.

In the pneumatic tire, the projection is the shortest with the groove wall at a position within the range of 0% to 30% of the height of the projection from the tip of the projection toward the groove bottom side. With respect to the minimum width d ₃ at a position where the distance d ₂ is in the range of 30% to 60% of the groove depth from the groove bottom to the opening side in the groove having the bent portion, It is preferable to have at least one portion where 1.2 d ₃ d d ₂ .

In the pneumatic tire, the protrusion has the bent portion at a position closer to the groove bottom than the bent portion in two opposing groove walls and a diameter φdp of a circle contacting the protrusion. It is preferable to be within the range of 0 <(φdp / d ₁ ) ≦ 1.2 with respect to the groove width d ₁ at the position of the bent portion of the groove.

In the pneumatic tire, the protrusion is a groove wall of the circumferential groove and the width direction groove, the two groove walls facing each other across at least a part of the protrusion, and a tip of the protrusion diameter circle .phi.DC1 touching the part is, the bent portions facing each other in the groove having the bent portion, with respect to the distance d ₄ on the circular flush, 0 <(φdc / d 4 ) ≦ It is preferable to be in the range of 1.2.

In the pneumatic tire, a plurality of the protrusions are provided in one groove, and a distance Lp between adjacent protrusions is a groove at a position of the bent portion of the groove having the bent portion. Preferably, the relationship with the width d ₁ is (Lp / d ₁ ) ≧ 5.

  The pneumatic tire according to the present invention has an effect that it is possible to improve the anti-stone-drilling property of the groove.

FIG. 1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment. FIG. 2 is a detailed view of part A of FIG. FIG. 3 is a cross-sectional view taken along line B-B and line C-C in FIG. FIG. 4 is a detail view of FIG. 2D and is an explanatory view of an intersection of the circumferential groove and the width direction groove. FIG. 5 is a cross-sectional view taken along the line E-E of FIG. FIG. 6 is a detail view of FIG. 2D, and is an explanatory view when defining the positional relationship between the protrusion and the groove wall using a circle. FIG. 7 is an F-F detail view of FIG. 6 and an explanatory view when defining the height of the protrusion using a circle. FIG. 8 is a schematic view showing a state in which a stone has entered a ditch. FIG. 9 is a schematic view showing a state in which a stone has entered the intersection of the grooves. FIG. 10: is a modification of the pneumatic tire concerning embodiment, and is explanatory drawing in case the side of a projection inclines. FIG. 11 is a modification of the pneumatic tire according to the embodiment, and is an explanatory view in the case where the number of bent portions of the groove wall of the groove is one. FIG. 12 is an explanatory view showing a state in which a projection is provided at the intersection of the grooves shown in FIG. Drawing 13 is a modification of a pneumatic tire concerning an embodiment, and is an explanatory view in a case where a projection is formed in shape of a rectangle. FIG. 14 is a modification of the pneumatic tire according to the embodiment, and is an explanatory view in the case where the protrusion is formed in a concave polygon shape. FIG. 15 is a modification of the pneumatic tire according to the embodiment, and is an explanatory view in the case where the protrusions are formed in a circular shape. Drawing 16 is a modification of a pneumatic tire concerning an embodiment, and is an explanatory view in a case where a projection is formed by elliptical shape. FIG. 17A is a chart showing the results of a performance evaluation test of a pneumatic tire. FIG. 17B is a chart showing the results of a performance evaluation test of a pneumatic tire.

  Below, an embodiment of a pneumatic tire concerning the present invention is described in detail based on a drawing. The present invention is not limited by this embodiment. Further, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art and those that are substantially the same.

  In the following description, the tire width direction refers to a direction parallel to the rotational axis of the pneumatic tire, the tire width direction inside refers to the direction toward the tire equatorial line in the tire width direction, and the tire width direction outside refers to the tire width. The direction opposite to the direction toward the tire equator line in the direction. Further, the tire radial direction means a direction orthogonal to the tire rotation axis, and the tire circumferential direction means a direction rotating around the tire rotation axis.

  FIG. 1 is a plan view showing a tread surface 3 of a pneumatic tire 1 according to an embodiment. In the pneumatic tire 1 shown in FIG. 1, the tread portion 2 is disposed at the outermost portion in the tire radial direction, and the surface of the tread portion 2, that is, the vehicle on which the pneumatic tire 1 is mounted (not shown) The portion in contact with the road surface when traveling in the) is formed as the tread surface 3. A plurality of grooves 10 are formed in the tread surface 3, and a plurality of circumferential grooves 21 extending in the tire circumferential direction and a plurality of width direction grooves 22 extending in the tire width direction are formed as the plurality of grooves 10. ing. In the present embodiment, two circumferential grooves 21 are provided on both sides of the tire equator line CL in the tire width direction, and a total of four circumferential grooves 21 are provided. Further, the width direction grooves 22 are disposed between the adjacent circumferential direction grooves 21 or outside the tire width direction of the outermost two circumferential direction grooves 21 in the tire width direction, and a plurality of the width direction grooves 22 are provided at these positions. It is provided along the circumferential direction.

  Further, each width direction groove 22 intersects with the circumferential direction groove 21, that is, an end communicates with the circumferential direction groove 21. That is, the width direction grooves 22 disposed between the circumferential direction grooves 21 adjacent to each other intersect the circumferential direction grooves 21 positioned on both sides in the tire width direction of the width direction groove 22, whereby the tire width is obtained. Both ends in the direction communicate with the circumferential groove 21 respectively. Further, the width direction grooves 22 disposed on the outer side in the tire width direction of the two outermost circumferential grooves 21 in the tire width direction are the same as the circumferential groove 21 located on the inner side in the tire width direction of the width direction groove 22. The inner end in the tire width direction is in communication with the circumferential groove 21 by intersecting with it.

  A plurality of land portions 5 defined by the circumferential grooves 21 and the width direction grooves 22 are formed on the tread surface 3. In the pneumatic tire 1 according to the present embodiment, since the land portion 5 is thus defined by the circumferential grooves 21 and the width direction grooves 22, the tread pattern formed on the tread surface 3 by the grooves 10 is a so-called tread pattern. It is a block pattern.

  Among the grooves 10 formed in these manners, the groove width of the opening in the circumferential direction groove 21 is in the range of 8 mm or more and 15 mm or less, and the groove depth is in the range of 9 mm or more and 30 mm or less There is. The width direction groove 22 has a groove width in the range of 3 mm to 15 mm, and a groove depth in the range of 9 mm to 30 mm. In addition, the circumferential grooves 21 and the width direction grooves 22 have the same groove depth. Specifically, in the circumferential grooves 21 and the width direction grooves 22, the difference in groove depth is within a range of ± 10% with respect to at least one of the groove depths, and the difference in groove depth is It is preferable to be in the range of ± 5%.

  The circumferential grooves 21 may not be formed linearly along the tire circumferential direction, and may be repeatedly bent or curved in the tire width direction while extending in the tire circumferential direction. Further, the width direction grooves 22 may not be formed linearly along the tire width direction, and may extend in the tire width direction and incline in the tire circumferential direction, or may extend in the tire width direction and bend in the tire circumferential direction It may be bent or curved. Further, the circumferential groove 21 has not only a so-called circumferential main groove having a tread wear indicator display duty that is a slip sign inside but also a groove 10 extending in the tire circumferential direction without having a tread wear indicator display duty included. In addition to the circumferential grooves 21 and the width direction grooves 22, grooves 10 other than the grooves 10 may be formed in the tread surface 3.

  FIG. 2 is a detailed view of part A of FIG. A plurality of width direction grooves 22 formed in the tread surface 3 do not penetrate the circumferential direction groove 21 in the tire width direction, and a plurality of widths connected to one circumferential direction groove 21 from both sides in the tire width direction The directional grooves 22 are disposed at different positions in the tire circumferential direction. For this reason, the circumferential grooves 21 and the width direction grooves 22 which intersect with each other intersect in a T-shape.

  FIG. 3 is a cross-sectional view taken along line B-B and line C-C in FIG. The circumferential grooves 21 and the width direction grooves 22 have the same shape when viewed in the extending direction of the grooves 10. The following description will be made using the circumferential groove 21 as a representative. The circumferential groove 21 is formed to have a stepped portion 17 by having the groove portions 11 opposed to each other and having a bent portion 14. Specifically, the groove wall 11 of the circumferential groove 21 is a first bent portion 15 formed in a portion continuing from the opening 13 in the groove wall 11 as the bent portion 14 and the groove bottom 12 in the groove wall 11 And a second bent portion 16 formed in a continuous portion.

  In the groove wall 11, a portion formed from the first bending portion 15 toward the opening 13 is formed at an angle close to the groove depth direction, and from the first bending portion 15 toward the groove bottom 12 The portion to be formed is formed at an angle close to the groove width direction, and the first bending portion 15 is a crossing portion of a portion of the groove wall 11 having different angles. Further, in the groove wall 11, a portion formed from the second bent portion 16 toward the opening 13 is formed at an angle close to the groove width direction, and from the second bent portion 16 toward the groove bottom 12 The portion to be formed is formed at an angle close to the groove depth direction, and the second bending portion 16 is a crossing portion of a portion of the groove wall 11 having different angles.

  Further, the first bent portion 15 and the second bent portion 16 are substantially at the same position in the groove depth direction, and the second bent portion 16 is in the groove width direction more than the first bent portion 15. It is located inside. For this reason, the portion between the first bent portion 15 and the second bent portion 16 in the groove wall 11 is a stepped portion 17 formed at an angle close to parallel to the tread surface 3, and the circumferential direction The groove wall 11 of the groove 21 is formed in a altar shape having a stepped portion 17 substantially parallel to the tread surface 3.

As described above, in the bending portion 14 of the groove wall 11, the second bending portion 16 is positioned more inward in the groove width direction than the first bending portion 15. The groove width on the groove bottom 12 side is narrower than the groove width W ₁ of the opening 13 of the circumferential groove 21, and the groove width on the groove bottom 12 side of the bent portion 14 is equal to that of the opening 13. It has become narrow portion 18 formed by a narrower width than the groove width W _1. In other words, in the groove wall 11 of the circumferential groove 21, the portion located closer to the groove bottom 12 than the bent portion 14 is inward in the groove width direction with respect to the portion located closer to the opening 13 than the bent portion 14. A portion which is protruded and which protrudes inward in the groove width direction in the groove wall 11 forms a narrow portion 18. Here, the inside in the groove width direction means a direction toward the center side in the groove width direction.

Further, the circumferential grooves 21, the groove width _{W 1} of the opening 13, the relationship between the groove width _{W 2} at 1/2 of the position of the groove depth Hg from the opening 13 to the groove bottom 12, 0 < It is within the range of (W ₂ / W ₁ ) ≦ 0.5. In the present embodiment, since the second bent portion 16 is positioned at a half position of the groove depth Hg of the circumferential groove 21, the half of the groove depth Hg from the opening 13 to the groove bottom 12 the groove width W ₂ at the position of the is adapted to the groove width W ₂ at the position of the second bend 16.

The shapes of the circumferential groove 21 and the width direction groove 22 have been described using the circumferential direction groove 21 as a representative, but the width direction groove 22 is also formed in the same shape as the circumferential groove 21. That is, similarly to the circumferential groove 21, the width direction groove 22 also has the narrow portion 18 by having the first bending portion 15 and the second bending portion 16 as the bending portion 14, and the groove wall 11 has a step The attached portion 17 is formed. Thus, the groove wall 11 of the width direction groove 22 is also formed in a ladder shape. Further, in the width direction groove 22 as well as the circumferential direction groove 21, the groove width W ₂ of the opening 13 and the groove width W ₂ at a half of the groove depth Hg from the opening 13 to the groove bottom 12 The relationship with is in the range of 0 <(W ₂ / W ₁ ) ≦ 0.5.

  The bent portions 14 formed on the groove walls 11 of the circumferential grooves 21 and the width direction grooves 22 are each in a range of 30% to 60% of the groove depth Hg from the groove bottom 12 toward the opening 13 side. It is preferably located in

  In the present embodiment, the chamfered portion 6 is formed at the corner where the circumferential groove 21 and the width direction groove 22 cross in the land portion 5. Specifically, the chamfered portion 6 is formed on the groove wall 11 of a portion of the width direction groove 22 communicating with the circumferential direction groove 21. The chamfered portion 6 of the groove wall 11 of the widthwise groove 22 is in the widthwise direction as it approaches the circumferential groove 21 from a position away from the circumferential groove 21 in the vicinity of the portion of the widthwise groove 22 communicating with the circumferential groove 21. The groove width of the groove 22 is formed to be wide. The chamfered portion 6 formed in the portion of the width direction groove 22 communicating with the circumferential groove 21 is also formed in the same shape as the shape of the groove wall 11 other than the chamfered portion 6. That is, the groove wall 11 of the chamfered portion 6 also has a bent portion 14 formed in the groove wall 11 and is formed in a altar shape having a stepped portion 17 substantially parallel to the tread surface 3.

  FIG. 4 is a detail view of FIG. 2D, and is an explanatory view of a crossing portion 25 between the circumferential groove 21 and the width direction groove 22. As shown in FIG. At the intersection 25 between the circumferential groove 21 and the width direction groove 22, a protrusion 30 is provided which is separated from the circumferential groove 21 and the groove wall 11 of the width direction groove 22 and protrudes from the groove bottom 12. Here, at the position where the width direction groove 22 communicates with the circumferential direction groove 21, the crossing portion 25 has a width direction groove with an opening width Wo of the width direction groove 22 across the groove width direction of the circumferential direction groove 21. It is an area formed by extending 22. The opening width Wo of the width direction groove 22 in this case is a dimension including the chamfered portion 6.

  At least a part of the protrusion 30 is formed at the intersection 25 of the circumferential groove 21 and the width direction groove 22. In the present embodiment, the protrusion 30 is formed in a trapezoidal shape in a plan view. In the projection 30 formed in a trapezoidal shape, the two base sides are parallel to the extending direction of the circumferential groove 21 and the shorter base side of the two base sides is the circumferential groove 21. The width direction grooves 22 are disposed in the direction in which they are in communication with each other. In addition, the planar view in this case indicates that the groove 10 is viewed in the groove depth direction.

FIG. 5 is a cross-sectional view taken along the line E-E of FIG. The protrusion 30 is formed to project from the groove bottom 12 of the intersection 25 of the circumferential groove 21 and the width direction groove 22 toward the opening 13 of the circumferential groove 21, and the height from the groove bottom 12 H ₁ falls within the range of 0.03 ≦ (H ₁ / H ₀ ) ≦ 2.0 with respect to the groove depth H ₀ from the bent portion 14 of the groove 10 having the bent portion 14 to the groove bottom 12 ing. The groove depth H ₀ from the bent portion 14 to the groove bottom 12 is the groove depth from the bent portion 14 to the groove bottom 12 when both the grooves 10 in the circumferential direction groove 21 and the width direction groove 22 have the bent portions 14. When each groove 10 is different, the groove depth from the bent portion 14 to the groove bottom 12 provided in the groove wall 11 directly connected to the groove bottom 12 in which the projection 30 is provided, and preferably, comparing the height H _1.

Further, the height H ₁ from the groove bottom 12 is 0.1 ≦≦ (the groove depth Hg from the opening 13 of the groove 10 to the groove bottom 12 at the position of the intersection 25). It is in the range of H ₁ /Hg)≦0.4. Furthermore, the height H1 of the protrusion 30 has a height of ₁ mm or more. Further, the protrusion 30 has the same shape as the shape of the portion connected to the groove bottom 12 and protrudes from the groove bottom 12 toward the opening 13. Therefore, the side surface 32 of the protrusion 30 is a groove The surface 10 extends in the groove depth direction.

Further, the protrusion 30 is at the position in the height range of 30% to 0% of _{H 1} Rp of the tip portion 31 protruding portion 30 toward the groove bottom 12 side from the protruding portion 30, the groove 10 groove wall shortest distance _{d 2} and 11, relative to the groove width _{d 1} at the position of the bent portion 14 of the groove 10 having a bent portion 14 has at least one place a portion to be a 1.2d ₁ ≧ _{d 2} .

The tip 31 of the projection 30 in this case is an end located on the opposite side of the end of the projection 30 on the groove bottom 12 side. The groove walls 11 having the shortest distance d ₂ relative to the protrusion portion 30 can be any of the groove wall 11 of the groove wall 11 and the widthwise grooves 22 in the circumferential groove 21. The groove width d ₁ at the position of the bent portion 14, if the both groove 10 of the circumferential groove 21 and the widthwise grooves 22 the groove width at the position of the bent portion 14 is different in the case having a bent portion 14 it is preferably compared with the groove width d ₁ of the larger groove width at the position of the bent portion 14 and the shortest distance d _2.

Furthermore, in the protrusion 30, the shortest distance d ₂ to all the groove walls 11 facing the protrusion 30 is 0 <(d ₂ / d ₁ ) with respect to the groove width d ₁ at the position of the bending portion 14. Preferably, it is formed within the range of ≦ 1.5. That is, the protrusion 30 is 0% or more and 30% or less of the height H ₁ of the protrusion 30 from the tip 31 toward the groove bottom 12 with respect to any groove wall 11 facing the protrusion 30. the shortest distance _{d 2} between the groove wall 11 at a position within the range Rp is against the groove width _{d 1} at the position of the bent portion 14, formed in the range of _{0 <(d 2 / d 1} ) ≦ 1.5 Is preferred.

6 is a detail view of FIG. 2D and is an explanatory view when defining the positional relationship between the protrusion 30 and the groove wall 11 using a circle 41. FIG. When the projection 30 sets a virtual circle 41 in contact with the projection 30 and a position on the groove bottom 12 side of the two groove walls 11 facing each other in the plan view of the groove 10, the circle The diameter φdp of 41 is in the range of 0 <(φdp / d ₁ ) ≦ 1.2 with respect to the groove width d ₁ at the position of the bent portion 14 of the groove 10 having the bent portion 14. That is, in the protrusion 30, the size of the space formed between the narrow portion 18 of the groove 10 and the groove wall 11 is predetermined with respect to the groove width of the narrow portion 18 of the groove 10 having the bending portion 14. It is in the range of In this case, the two groove walls 11 in contact with the circle 41 may not be the parallel groove walls 11. For example, the groove wall 11 on the opposite side to the side in which the width direction grooves 22 in the circumferential direction groove 21 communicate. And the groove wall 11 of the chamfered portion 6 in the width direction groove 22.

FIG. 7 is an F-F detail view of FIG. 6 and an explanatory view when defining the height of the protrusion 30 using a circle 42. Of the groove walls 11 of the circumferential groove 21 and the width direction groove 22, the projection 30 is formed by two groove walls 11 opposed to each other across at least a part of the projection 30 and the tip 31 of the projection 30. When the imaginary circle 42 in contact is set, the diameter φdc of the circle 42 is the same as the distance d ₄ on the same plane as the circle 42 of the opposing bending portions 14 in the groove 10 having the bending portion 14 It is in the range of 0 <(φdc / d ₄ ) ≦ 1.2. That is, the height H ₁ from the groove bottom 12 where the protrusion 30 is provided is within a predetermined range with respect to the distance between the two groove walls 11 opposed to each other with the protrusion 30 interposed therebetween. There is. In this case, the two groove walls 11 in contact with the circle 42 are the groove wall 11 of the circumferential groove 21 shown in FIGS. 2 and 7 and the groove wall 11 of the chamfered portion 6 in the width direction groove 22. , And may not be parallel groove walls 11.

Furthermore, although a plurality of protrusions 30 are provided in one groove 10, the distance Lp between the adjacent protrusions 30 (see FIG. 2) has a relationship with the groove width d ₁ at the position of the bending portion 14 It is preferable that (Lp / d ₁ ) ≧ 5.

  The pneumatic tire 1 according to the present embodiment configured as described above is used as a heavy load pneumatic tire. When the pneumatic tire 1 is mounted on a vehicle, the pneumatic tire 1 is mounted on the vehicle in a state of being rim-assembled on a rim wheel. The pneumatic tire 1 in a state of being rim-assembled on a rim wheel is used by being attached to a large vehicle such as a truck or a bus, for example.

  When the vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while the tread surface 3 positioned below the tread surface 3 is in contact with the road surface. When traveling on a dry road surface with a vehicle equipped with the pneumatic tire 1, the driving force and the braking force are transmitted to the road surface or the turning force is generated mainly by the frictional force between the tread surface 3 and the road surface. Run by letting it go. In addition, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters the grooves 10 such as the circumferential grooves 21 and the width direction grooves 22, and the tread surface 3 and the road surface Run while draining the water between. As a result, the tread surface 3 can easily come in contact with the road surface, and the frictional force between the tread surface 3 and the road surface enables the vehicle to travel.

  FIG. 8 is a schematic view showing a state in which the stone 50 has entered the groove 10. A stone 50 may fall on the road surface on which the vehicle travels, and such a stone 50 on the road surface may enter the groove 10 of the tread surface 3 when the vehicle travels. In particular, some vehicles travel on so-called off-roads where many stones are scattered without being paved by asphalt or the like, and when traveling off-roads, the stones 50 are made of circumferential grooves 21 and width direction grooves 22 etc. It becomes easy to enter the groove 10. For example, since the circumferential groove 21 continues to open to the road surface when the pneumatic tire 1 rotates, the position of the stone 50 in the tire width direction on the road surface overlaps the position of the circumferential groove 21. This stone 50 enters the circumferential groove 21. Further, since the width direction groove 22 extends in the tire width direction, the position of the stone 50 and the position of the width direction groove 22 are easily overlapped in a wide area in the contact region of the tread surface 3. When the position and the position of the widthwise groove 22 overlap, the stone 50 enters the widthwise groove 22.

  As described above, the stones 50 on the road surface may enter the circumferential grooves 21 and the width direction grooves 22. However, in these grooves 10, a bending portion 14 is formed in the groove wall 11, and from the bending portion 14 The groove width of the groove bottom 12 is narrower than the groove width of the opening 13 of the groove 10. For this reason, the stone 50 which has entered the circumferential grooves 21 and the width direction grooves 22 is less likely to enter the groove bottom 12 side than the position of the bending portion 14. Specifically, the stone 50 which has entered the circumferential groove 21 or the width direction groove 22 contacts the stepped portion 17 formed by the formation of the bent portion 14 in the groove wall 11, and from the stepped portion 17 It is difficult to get into the narrow portion 18 side. Thereby, the stone 50 which has entered the circumferential groove 21 and the width direction groove 22 hardly reaches the groove bottom 12, and the stone 50 which has entered the groove 10 bites into the groove bottom 12 and the groove bottom 12 is damaged. It is possible to suppress the occurrence of so-called stone drilling.

  FIG. 9 is a schematic view showing a state in which the stone 50 has entered the intersection 25 of the groove 10. Even when the bent portion 14 is formed on the groove wall 11 of the groove 10, the cross portion 25 where the circumferential groove 21 and the width direction groove 22 intersect has a large area of the groove bottom 12 in plan view. The stone 50 which has entered is directed to the groove bottom 12 side more than the bending portion 14, and easily reaches the groove bottom 12. On the other hand, in the pneumatic tire 1 according to the present embodiment, the protrusion 30 that protrudes from the groove bottom 12 is provided at the intersection 25 between the circumferential groove 21 and the width direction groove 22. The stone 50 which has entered the intersection 25 of the groove 21 and the width direction groove 22 contacts the projection 30 and is difficult to directly contact the groove bottom 12. Thereby, the stone 50 which has entered the intersection 25 of the circumferential groove 21 and the width direction groove 22 is difficult to reach the groove bottom 12 even at the intersection 25 where the area of the groove bottom 12 in a plan view is large. Stone drilling into the intersection 25 can suppress the occurrence of stone drilling. As a result, the stone drilling resistance of the groove 10 can be improved.

  When the circumferential groove 21 and the width direction groove 22 have the same groove depth, the area of the groove bottom 12 tends to be large at the intersection 25 of the circumferential direction groove 21 and the width direction groove 22, Although 50 easily enters, the pneumatic tire 1 according to the present embodiment is provided with the projections 30 at the intersections 25, so that the stones 50 entering the intersections 25 are prevented from reaching the groove bottom 12. can do. Thereby, since the groove depth of the circumferential direction groove | channel 21 and the width direction groove | channel 22 is equal, the stone drilling in the cross | intersection part 25 which the stone 50 enters easily can be suppressed. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

In addition, the protrusion 30 has a shortest distance d _{2 from the} groove wall 11 at a position within a range Rp of 0% or more and 30% or less of the height H ₁ of the protrusion 30 from the tip 31 toward the groove bottom 12 side. Since at least one portion having 1.2 d ₁ d d ₂ with respect to the groove width d ₁ at the position of the bending portion 14, the stone 50 which has entered the intersection portion 25 reaches the groove bottom 12, This can be suppressed more reliably. That is, if the shortest distance _{d 2} between the protrusion 30 and the groove wall 11, no 1.2d ₁ ≧ _{d 2} to become part relative to the groove width _{d 1} at the position of the bent portion 14, the protrusion Since any portion 30 is too far from the groove wall 11, the stone 50 which has entered the intersection 25 may easily enter between the protrusion 30 and the groove wall 11. In this case, the projection 30 may make it difficult to suppress the arrival of the stone 50 that has entered the intersection 25 to the groove bottom 12.

If contrast, the shortest distance _{d 2} between the protrusion 30 and the groove wall 11, having at least one location becomes 1.2d ₁ ≧ _{d 2} relative to the groove width _{d 1} at the position of the bent portion 14, cross Since the stone 50 which has entered the portion 25 is easily brought into contact with the projection 30, the projection 30 can more reliably prevent the stone 50 which has entered the intersection 25 from reaching the groove bottom 12. Occurrence of stone drilling can be suppressed more reliably. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

Further, in the protrusion 30, the shortest distance d ₂ to all the groove walls 11 facing the protrusion 30 is 0 <(d ₂ / d ₁ ) with respect to the groove width d ₁ at the position of the bent portion 14. Since it is formed in the range of ≦ 1.5, the movement of the stone 50 entering the intersection 25 to the groove bottom 12 side can be more reliably suppressed by the projection 30. That is, a portion shortest distance _{d 2} and all the groove walls 11 facing the protruding portion 30, which is a _{(d 2} / d 1)> 1.5 relative to the groove width _{d 1} at the position of the bent portion 14 In the case of having, because there is a part where the distance between the projection 30 and the groove wall 11 is large, the stone 50 which has entered the intersection 25 enters the part where the distance between the projection 30 and the groove wall 11 is large. There is a risk of becoming easier. In this case, the projection 30 may make it difficult to suppress the arrival of the stone 50 that has entered the intersection 25 to the groove bottom 12.

In contrast, the shortest distance _{d 2} and all the groove walls 11 facing the protruding portion 30, with respect to the groove width _{d 1} at the position of the bent portion _{14, 0 <(d 2 /} d 1) ≦ 1. In the range of 5, the movement of the stone 50 entering the intersection 25 toward the groove bottom 12 can be more reliably suppressed by the projection 30, and the occurrence of stone drilling can be suppressed more reliably. be able to. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

Further, the height H ₁ from the groove bottom 12 of the protrusion 30 is 0.03 ≦ (H relative to the groove depth H ₀ from the bend 14 to the groove bottom 12 of the groove 10 having the bend 14. _Since it is in the range of ₁ / H ₀ ) ≦ 2.0, damage to the groove bottom 12 by the stone 50 that has entered the intersection 25 can be more reliably and continuously suppressed by the projection 30. That is, when the height H ₁ of the protrusion 30 is (H ₁ / H ₀ ) <0.03 with respect to the groove depth H ₀ from the bent portion 14 to the groove bottom 12, the intersection of the grooves 10 When the stone 50 which has entered the portion 25 contacts the projection 30 and the projection 30 itself is damaged, the height H ₁ of the projection 30 is too low, so the damage by the stone 50 reaches the groove bottom 12 May be difficult to control. When the height H ₁ of the protrusion 30 is (H ₁ / H ₀ )> 2.0 with respect to the groove depth H ₀ from the bent portion 14 to the groove bottom 12, the height H ₁ of the protrusion 30 is since the height H ₁ is too high, there is a possibility that the rigidity of the protrusion 30 becomes too low. In this case, when the stone 50 which has entered the intersection 25 of the groove 10 comes into contact with the projection 30, the force applied from the stone 50 may cause chipping or flaking in the projection 30, and the intersection 25 There is a possibility that it will become difficult to control the arrival of the intruded stone 50 to the groove bottom 12 continuously by the projections 30.

On the other hand, the height H ₁ of the protrusion 30 is within the range of 0.03 ≦ (H ₁ / H ₀ ) ≦ 2.0 with respect to the groove depth H ₀ from the bent portion 14 to the groove bottom 12. In this case, when the stone 50 that has entered the intersection 25 of the groove 10 makes contact with the projection 30, generation of chipping or flaking on the projection 30 can be suppressed, and the stone that has entered the intersection 25 Damage to the groove bottom 12 by 50 can be more reliably and continuously suppressed by the projection 30. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

Further, the height H ₁ from the groove bottom 12 of the protrusion 30 is 0.1 ≦ (H ₁ / H) with respect to the groove depth Hg from the opening 13 to the groove bottom 12 at the intersection 25. Since Hg) ≦ 0.4, damage to the groove bottom 12 by the stone 50 that has entered the intersection 25 can be more reliably and continuously suppressed by the projection 30. That is, when the height H ₁ of the protrusion 30 is (H ₁ /Hg)<0.1 with respect to the groove depth Hg of the groove 10 at the position of the intersection 25, the intersection of the groove 10 When the stone 50 which has entered 25 comes into contact with the protrusion 30 and the protrusion 30 itself is damaged, the height H ₁ of the protrusion 30 is too low, so the damage by the stone 50 extends to the groove bottom 12 May be difficult to control. Further, when the height H ₁ of the protrusion 30 is (H ₁ /Hg)>0.4 with respect to the groove depth Hg of the groove 10 at the position of the intersection 25, the height of the protrusion 30 is it is for H ₁ is too high, there is a possibility that the rigidity of the protrusion 30 becomes too low. In this case, when the stone 50 which has entered the intersection 25 of the groove 10 comes into contact with the projection 30, the force applied from the stone 50 may cause chipping or flaking in the projection 30, and the intersection 25 There is a possibility that it will become difficult to control the arrival of the intruded stone 50 to the groove bottom 12 continuously by the projections 30.

On the other hand, the height H ₁ of the projection 30 is within the range of 0.1 ≦ (H ₁ /Hg)≦0.4 with respect to the groove depth Hg of the groove 10 at the position of the intersection 25. In some cases, when the stone 50 that has entered the intersection 25 of the groove 10 comes into contact with the projection 30, generation of chipping or flaking can be suppressed in the projection 30, and the stone 50 that has entered the intersection 25 Damage to the groove bottom 12 can be more reliably and continuously suppressed by the projection 30. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

Further, in the groove 10 having the bending portion 14, the relationship between the groove width W ₁ of the opening 13 and the groove width W ₂ at a half of the groove depth Hg is 0 <(W ₂ / W ₁ Since it is in the range of 0.5), it can control more reliably that stone 50 which entered slot 10 reaches slot bottom 12. That is, when the groove width W ₂ at a half position of the groove depth Hg is (W ₂ / W ₁ )> 0.5 with respect to the groove width W ₁ of the opening 13, the groove depth since too large groove width W ₂ at 1/2 position of hg, even when the bent portion 14 provided in the groove 10, difficult to prevent the stone 50 which has entered the groove 10 reaches the groove bottom 12 There is a risk of becoming

In contrast, the groove width _{W 2} at 1/2 position of the groove depth Hg, relative to the groove width _{W 1} of the opening _{13, 0 <(W 2 /} W 1) ≦ 0.5 in the range of In this case, the bent portion 14 provided in the groove 10 can more reliably suppress the stone 50 that has entered the groove 10 from reaching the groove bottom 12. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

  In addition, since the bending portion 14 is positioned within a range of 30% to 60% of the groove depth Hg from the groove bottom 12 toward the opening 13 side, it is possible to prevent deterioration of the drainage property of the groove bottom 12. Damage can be suppressed more reliably. That is, when the position of the bending portion 14 is less than 30% of the groove depth Hg from the groove bottom 12 toward the opening 13 side, the position of the bending portion 14 approaches the groove bottom 12 too much. There is a risk that it may be difficult to properly block the entering stone 50 at the position of the bending portion 14. In this case, the stone 50 may come into contact with the groove bottom 12 with a large force, and it may be difficult to suppress damage to the groove bottom 12 due to the stone 50 entering the groove 10. When the position of the bending portion 14 exceeds 60% of the groove depth Hg from the groove bottom 12 toward the opening 13 side, the position of the bending portion 14 approaches the opening 13 too much, so the narrow portion 18 Of the groove 10 may be too large, and the volume of the groove 10 may be too small. In this case, since the amount of water entering the groove 10 is reduced, the drainage performance by the groove 10 is reduced, and there is a possibility that the wet steering safety, which is the steering stability when traveling on a wet road surface, is reduced.

  On the other hand, when the position of the bending portion 14 is positioned in the range of 30% to 60% of the groove depth Hg from the groove bottom 12 toward the opening 13 side, the deterioration of the drainage property is suppressed. Thus, the stone 50 that has entered the groove 10 can be reliably stopped at the position of the bending portion 14, and damage to the groove bottom 12 by the stone 50 can be suppressed more reliably. As a result, it is possible to more reliably improve the stone drilling resistance of the groove 10 while suppressing a decrease in wet steering.

Further, the protrusion 30 has a groove width at the position of the bending portion 14 and a position of a circle 41 in contact with the position of the groove bottom 12 side with respect to the bending portion 14 in the two groove walls 11 facing each other Since it is in the range of 0 <(φdp / d ₁ ) ≦ 1.2 with respect to d ₁ , the movement of the stone 50 entering the intersection 25 to the groove bottom 12 side is made more surely by the projection 30. It can be suppressed. That is, in the case where the diameter φdp of the circle 41 in contact with the two groove walls 11 and the projection 30 is (φdp / d ₁ )> 1.2 with respect to the groove width d ₁ at the position of the bending portion 14 The diameter φ dp of the circle 41 may be too large relative to the groove width d ₁ at the position of the bending portion 14, that is, the distance between the groove wall 11 and the projection 30 may be too large. In this case, there is a possibility that the stone 50 entering the intersection 25 may easily enter between the projection 30 and the groove wall 11, and the arrival of the stone 50 entering the intersection 25 to the groove bottom 12 is May be difficult to suppress.

On the other hand, the diameter dpdp of the circle 41 in contact with the two groove walls 11 and the protrusion 30 is 0 <(φdp / d ₁ ) ≦ 1.2 with respect to the groove width d ₁ at the position of the bending portion 14 The movement of the stone 50 entering the intersection 25 toward the groove bottom 12 can be more reliably suppressed by the projection 30, and the occurrence of stone drilling can be more reliably suppressed. Can. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

In addition, the protrusion 30 has a groove 10 having a bent portion 14 and a diameter φdc of a circle 42 in contact with the two groove walls 11 opposed to each other across at least a portion of the protrusion 30 and the tip portion 31 of the protrusion 30. Since it is in the range of 0 <(φdc / d ₄ ) ≦ 1.2 with respect to the distance d ₄ on the same plane as the circle 42 of the opposing bent portions 14 in the case, the stone which has entered the crossing portion 25 Damage to the groove bottom 12 by 50 can be more reliably and continuously suppressed by the projection 30. In other words, the two groove walls 11, the diameter .phi.DC1 of a circle 42 in contact with the tip portion 31 of the protrusion 30 with respect to the distance _{d 4} of the bent portion 14 to each other on the circle 42 and the same plane, (.phi.DC1 / d ₄₎ If> 1.2, the diameter φdc circle 42, there is a possibility too large for the distance _{d 4} of the bent portion 14 to each other on the circle 42 in the same plane, i.e., the position of the bent portion 14 there is a possibility the height H ₁ of the protrusion 30 is too high for. In this case, the rigidity of the projection 30 becomes too low, and when the stone 50 contacts the projection 30, the projection 30 may be chipped or chipped, and the groove bottom of the stone 50 which has entered the intersection 25 There is a possibility that it will be difficult to suppress the reach to 12 continuously by the projection 30.

In contrast, the two groove walls 11, the diameter φdc of a circle 42 in contact with the tip portion 31 of the protrusion 30 with respect to the distance _{d 4} of the bent portion 14 to each other on the circle 42 in the same plane, 0 < When it is within the range of (φdc / d ₄ ) ≦ 1.2, when the stone 50 which has entered the intersection 25 of the groove 10 contacts the projection 30, chipping or peeling may occur in the projection 30. Damage to the groove bottom 12 due to the stone 50 that has entered the intersection 25 can be suppressed continuously by the projection 30 more reliably. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

In addition, since the distance Lp between adjacent protrusions 30 has a relationship with the groove width d ₁ at the position of the bent portion 14 of the groove 10, (Lp / d ₁ ) ≧ 5, the drainage property of the groove 10 is It is possible to suppress the decrease or the decrease in the durability. That is, when the distance Lp between the adjacent protrusions 30 is (Lp / d ₁ ) <5 with respect to the groove width d ₁ at the position of the bending portion 14, the distance Lp between the adjacent protrusions 30 is Since it is too small, there is a possibility that drainage nature of slot 10 in which the projection part 30 concerned is provided may fall. Further, the fact that the distance Lp between adjacent protrusions 30 is too small means, in other words, the number of protrusions 30 is large, and the amount of rubber used is large. If the amount of rubber is large, heat is likely to be generated when the pneumatic tire 1 rotates, so the heat is likely to deteriorate the rubber, and the durability may be easily reduced.

On the other hand, when the distance Lp between adjacent protrusions 30 is (Lp / d ₁ )) 5 with respect to the groove width d ₁ at the position of the bending portion 14, the distance between the adjacent protrusions 30 is It can suppress that Lp becomes small too much, and it can control that drainage nature of ditch 10 falls, or it becomes easy to fall in durability. As a result, it is possible to more reliably improve the stone drilling resistance of the groove 10 while suppressing the decrease in wet steering stability and the decrease in durability.

[Modification]
In the pneumatic tire 1 according to the embodiment described above, the protrusion 30 has the same shape as the shape of the portion connected to the groove bottom 12 and protrudes from the groove bottom 12 toward the opening 13. The shape of the protrusion 30 may be different depending on the position of the groove 10 in the groove depth direction. Drawing 10 is a modification of pneumatic tire 1 concerning an embodiment, and is an explanatory view in case side 32 of projection part 30 inclines. As shown in FIG. 10, the projection 30 provided at the intersection 25 between the circumferential groove 21 and the width direction groove 22 is formed with the side surface 32 inclined with respect to the groove depth direction of the groove 10 Good. That is, the protrusion 30 may be formed such that the area in plan view decreases as going from the groove bottom 12 to the opening 13 of the groove 10. Alternatively, the protrusion 30 may be formed in a curved shape such that the tip 31 is not a flat surface but is, for example, convex toward the opening 13 of the groove 10. Even in these cases, the projection 30 is the shortest distance to the groove wall 11 at a position within the range Rp of 0% or more and 30% or less of the height H ₁ of the projection 30 from the tip 31 toward the groove bottom 12 side. d ₂ is, or has at least one location 1.2d ₁ ≧ _{d 2} to become part relative to the groove width _{d 1} at the position of the bent portion 14, the shortest and all groove wall 11 that faces the protrusion 30 The distance d ₂ may be formed in the range of 0 <(d ₂ / d ₁ ) ≦ 1.5.

In the pneumatic tire 1 according to the embodiment described above, the shortest distance d ₂ between the protrusion 30 and the groove wall 11, by comparing the groove width d ₁ at the position of the bent portion 14, and the protrusion 30 Although the relative relationship with the groove wall 11 is defined, the relative relationship between the protrusion 30 and the groove wall 11 may be defined based on other criteria. For example, the projections 30, the shortest and the groove wall 11 at the position in the height range of 30% to 0% of _{H 1} Rp protrusions 30 from the distal end portion 31 toward the groove bottom 12 side of the protrusion 30 distance _{d 2} is, in the groove 10 having a bent portion 14 at a position in more than 30% of the groove depth Hg toward the groove bottom 12 to the opening 13 side of 60% or less of the range Rg (see FIG. 10) of the top It is sufficient to have at least one portion where 1.2d ₃ dd ₂ with respect to the small width d ₃ . Thus, the shortest distance _{d 2} between the protrusion 30 and the groove wall 11, with respect to the minimum width _{d 3} at the position of the groove depth range of 30% to 60% or less of Hg groove 10 Rg, 1 By having at least one portion where 2d ₃ dd ₂ , the projection 30 can more reliably suppress the stone 50 entering the intersection 25 from reaching the groove bottom 12. As a result, the stone drilling resistance of the groove 10 can be more reliably improved.

  Further, in the pneumatic tire 1 according to the embodiment described above, the circumferential groove 21 and the width direction groove 22 have two bending portions 14 of the first bending portion 15 and the second bending portion 16, Although the groove wall 11 is formed in a altar shape, the circumferential groove 21 and the width direction groove 22 may be formed in other shapes. Drawing 11 is a modification of pneumatic tire 1 concerning an embodiment, and is an explanatory view in a case where bent part 14 of slot wall 11 of slot 10 is one place. The circumferential grooves 21 and the width direction grooves 22 may have one bent portion 14 formed in each groove wall 11, as shown in FIG. In this case, the portion of the groove wall 11 between the opening 13 and the bending portion 14 is inclined in the direction in which the groove width becomes narrower as it goes from the opening 13 side to the bending portion 14 side. That is, the portion of the groove wall 11 between the opening 13 and the bending portion 14 is inclined in the direction in which the distance between the opposing groove walls 11 decreases from the opening 13 toward the bending portion 14. . Further, a portion between the bent portion 14 and the groove bottom 12 in the groove wall 11 is formed at an angle close to the groove depth direction, and the groove width which is the interval between the opposed groove walls 11 becomes substantially constant. ing. The bending portion 14 is a crossing portion of the groove wall 11 at different angles. Further, a portion between the bent portion 14 and the groove bottom 12 in the groove wall 11 is formed as a narrow portion 18 in which the groove width is narrower than the portion between the opening 13 and the bent portion 14 in the groove wall 11 It is done.

  Thus, the groove width of the circumferential groove 21 and the groove wall 11 of the width direction groove 22 gradually narrows from the opening 13 toward the bending portion 14, and the portion from the bending portion 14 to the groove bottom 12 is a bending portion It is formed in a funnel shape in which the groove width is narrower than the portion on the side of the opening 13 from the portion 14. Even if the groove walls 11 of the circumferential grooves 21 and the width direction grooves 22 each have one bent portion 14 in this way and are formed in a funnel shape, the stone 50 which has entered the grooves 10 is a bent portion 14. Therefore, the stone 50 can be prevented from reaching the groove bottom 12 and causing stone drilling.

  FIG. 12 is an explanatory view showing a state in which the projection 30 is provided at the intersection 25 of the groove 10 shown in FIG. Even when the circumferential grooves 21 and the groove walls 11 of the width direction grooves 22 are formed in a funnel shape, the cross section 25 of the circumferential grooves 21 and the width direction grooves 22 increases the area of the groove bottom 12 in plan view Therefore, the stone 50 that has entered the groove 10 can easily reach the groove bottom 12 at the intersection 25. For this reason, even when the groove walls 11 of the circumferential grooves 21 and the width direction grooves 22 are formed in a funnel shape, by providing the protrusions 30 at the intersections 25, the stone 50 which has entered the intersections 25 can be used as the projections 30. The projections 30 can prevent the stone 50 from reaching the groove bottom 12 and damaging the groove bottom 12. As a result, the stone drilling resistance of the groove 10 can be improved.

  Moreover, in the pneumatic tire 1 according to the embodiment described above, the protrusion 30 is formed in a trapezoidal shape in plan view, but the shape of the protrusion 30 is formed in a shape other than the trapezoidal shape. May be Drawing 13 is a modification of pneumatic tire 1 concerning an embodiment, and is an explanatory view in a case where projection 30 is formed in the shape of a rectangle. Drawing 14 is a modification of pneumatic tire 1 concerning an embodiment, and is an explanatory view in a case where projection 30 is formed in shape of a concave polygon. The protrusions 30 provided at the intersections 25 between the circumferential grooves 21 and the width direction grooves 22 may have, for example, a rectangular shape in plan view, as shown in FIG. As shown, it may be formed in the shape of a concave polygon. The shape of the protrusion 30 is preferably set appropriately in consideration of the drainage property and design property of the groove 10 and the like.

  Drawing 15 is a modification of pneumatic tire 1 concerning an embodiment, and is an explanatory view in a case where projection 30 is formed in circular shape. Drawing 16 is a modification of pneumatic tire 1 concerning an embodiment, and is an explanatory view in a case where projection 30 is formed by elliptical shape. Further, as shown in FIG. 15, the protrusions 30 provided at the intersections 25 between the circumferential grooves 21 and the width direction grooves 22 may be formed in a circular shape in plan view, as shown in FIG. As shown, it may be formed in an elliptical shape. By making the shape in a plan view of the protrusion 30 a shape such as a circle or an ellipse, which does not have a corner, when the stone 50 comes in contact with the protrusion 30, chipping or peeling occurs in the protrusion 30 Can be suppressed. As a result, damage to the groove bottom 12 by the stone 50 that has entered the intersection 25 can be continuously suppressed by the projection 30.

  Moreover, in the pneumatic tire 1 according to the embodiment described above, the groove walls 11 of both the circumferential groove 21 and the width direction groove 22 are formed to have the bending portion 14, but the bending portion of the groove wall 11 The groove wall 11 of at least one of the circumferential groove 21 and the width direction groove 22 intersecting at the intersection 25 may be provided in the groove 14. For example, when the groove width is narrow, the stone 50 does not easily enter the groove 10, so the groove width of any of the circumferential groove 21 and the width direction groove 22 is narrow to such an extent that the stone 50 is difficult to enter The groove wall 11 of the groove 10 may not have the bending portion 14.

  Moreover, in the pneumatic tire 1 according to the above-described embodiment, the circumferential grooves 21 and the width direction grooves 22 have the same groove depth, but the circumferential grooves 21 and the width direction grooves intersecting at the intersection portion 25 The groove depth may be different from each other. Even when the groove depth is different between the circumferential groove 21 and the width direction groove 22, the area of the groove bottom 12 in plan view tends to be large at the intersection 25, and therefore the projection 30 is provided at the intersection 25. The groove bottom 12 can be inhibited from being damaged by the stone 50, and the stone 10 drilling resistance of the groove 10 can be improved.

  Further, in the pneumatic tire 1 according to the above-described embodiment, the chamfered portion 6 is formed on the groove wall 11 of the portion of the width direction groove 22 communicating with the circumferential groove 21, but the chamfered portion 6 is not formed. May be Even if the chamfered portion 6 is not formed at the intersection of the circumferential groove 21 and the width direction groove 22, the intersection 25 of the circumferential groove 21 and the width direction groove 22 has an area of the groove bottom 12 in plan view. Is likely to increase. Therefore, even if the chamfered portion 6 is not formed at the intersection of the circumferential groove 21 and the width direction groove 22, the groove bottom 12 is damaged by the stone 50 by providing the protrusion 30 at the intersection 25. Can be suppressed, and the stone drilling resistance of the groove 10 can be improved.

  Moreover, in the pneumatic tire 1 according to the above-described embodiment, the circumferential groove 21 and the width direction groove 22 intersect in a T shape, but the circumferential groove 21 and the width direction groove 22 intersect in the width direction. The grooves 22 may cross so as to cross the circumferential grooves 21 and penetrate the circumferential grooves 21. Even when the circumferential groove 21 and the lateral groove 22 intersect so that the lateral groove 22 penetrates the circumferential groove 21, the intersection 25 of the circumferential groove 21 and the lateral groove 22 is a groove in plan view The area of the bottom 12 tends to be large. For this reason, even when the width direction groove 22 penetrates the circumferential direction groove 21, the groove bottom 12 can be prevented from being damaged by the stone 50 by providing the protrusion 30 at the intersection 25. Stone drilling resistance can be improved.

Further, in the pneumatic tire 1 according to the embodiment described above, the protrusions 30 are provided only at the intersections 25 between the circumferential grooves 21 and the width direction grooves 22, but the protrusions 30 are other than the intersections 25. It may be provided at the position of. Even in the case of providing at a position other than the crossing portion 25, the distance Lp between adjacent protrusions 30 is arranged in a positional relationship such that (Lp / d ₁ ) ≧ 5 with respect to the groove width d ₁ at the position of the bending portion 14. By the provision, it is possible to improve the stone drilling resistance of the groove 10 while suppressing the decrease in wet steering stability and the decrease in durability.

〔Example〕
FIGS. 17A and 17B are charts showing the results of the performance evaluation test of the pneumatic tire 1. Hereinafter, evaluation tests of performance of the pneumatic tire 1 according to the conventional example and the comparative example and the pneumatic tire 1 according to the present invention will be described. The performance evaluation test was performed on a test on the stone drilling resistance which is a performance on the difficulty of occurrence of the stone drilling in the groove 10 and a test on the heat buildup of the pneumatic tire 1 when the vehicle was driven.

  In these performance evaluation tests, the tire name specified by JATMA is a 295 / 75R22.5 size pneumatic tire 1 assembled to the rim wheel of the specified rim specified by JATMA, and the air pressure is specified by JATMA. The maximum air pressure was adjusted, and the test was carried out by mounting on a 2-D · 4 test vehicle (truck) and performing a test run.

  The evaluation method of each test item is, for the stone drilling resistance, between the circumferential groove 21 and the width direction groove 22 when the fixed vehicle of the quarry is made 10 laps at 20 km / h by the test vehicle equipped with the test tire. The number of stones 50 reaching the groove bottom 12 at the intersection 25 was counted, and the reciprocal of the number of stones 50 reaching the groove bottom 12 was indicated by an index where the number of conventional examples described later is 100. The larger the value, the smaller the number of stones 50 reaching the groove bottom 12 at the intersection 25 and the better the resistance to stone drilling.

  The heat buildup was performed by measuring the surface temperature of the test tire after traveling for 24 hours at a speed of 80 km / h by an indoor drum test. The evaluation result of the heat buildup is indicated by an index where the temperature of the conventional example described later is 100. The index is smaller as the measured temperature is higher.

  The performance evaluation test is performed on a pneumatic tire to be compared with a conventional example which is an example of a conventional pneumatic tire 1, Examples 1 to 14 which are a pneumatic tire 1 according to the present invention, and the pneumatic tire 1 according to the present invention It carried out about 17 types of pneumatic tires of comparative examples 1 and 2 which are. Among the pneumatic tires 1, in the pneumatic tire of the conventional example, the curved portion 14 is not provided on the groove wall 11 of the groove 10, and the groove 10 has a U-shaped cross section. Further, in the pneumatic tire of the conventional example, the protrusions 30 are not provided at the intersections 25 of the grooves 10. Moreover, although the pneumatic tire of Comparative Example 1 is provided with the bending portion 14 in the groove wall 11 of the groove 10 and the groove wall 11 is in a altar shape, the protrusion 30 is provided in the intersection 25 of the groove 10 Not. Moreover, although the pneumatic tire of Comparative Example 2 is provided with the protrusion 30 at the intersection 25 of the groove 10, the groove portion 11 of the groove 10 is not provided with the bent portion 14, and the cross-sectional shape is U-shaped. It has a groove 10 in the shape of a circle.

On the other hand, in Examples 1 to 14 which are an example of the pneumatic tire 1 according to the present invention, the bent portion 14 is provided on the groove wall 11 of the groove 10, and the protrusion 30 is formed on the intersection 25 of the groove 10. Is provided. Further, examples 1 to 14, or the shape of the groove 10 having a bent portion 14 is or funnel shape is terraced shape, the shortest distance d ₂ between the protrusion 30 and the groove wall 11, the position of the bent portion 14 relationship between the groove width _{d 1,} 0 shortest distance _{d 2} is relative to the groove width _{d 1} at the position of the bent portion 14 of the protrusion 30 and the groove wall _{11 <(d 2 / d 1} ) ≦ 1 at. 5, the relationship between the groove depth H ₀ from the bent portion 14 of the groove 10 to the groove bottom 12 and the height H ₁ of the protrusion 30 (H ₁ / H ₀ ), from the opening 13 of the groove 10 The relationship between the groove depth Hg to the groove bottom 12 and the height H ₁ of the protrusion 30 (H ₁ / Hg), the groove width W ₁ of the opening 13 of the groove 10, and the groove depth Hg of the groove 10 relationship between the groove width _{W 2} at the position of _{1/2 (W 2 / W 1)} , the position of the bent portion 14 from the groove bottom 12, the groove width _{d 1} at the position of the bent portion 14 of the groove 10, adjacent Cormorant projections 30 relationship between the distance Lp between (Lp / _{d 1)} are different respectively.

  As a result of conducting an evaluation test using these pneumatic tires 1, as shown to FIG. 17A and FIG. 17B, the pneumatic tire 1 of Examples 1-14 is compared with a prior art example and the comparative examples 1 and 2, It has been found that the stone drilling resistance is improved while maintaining the heat generation. That is, the pneumatic tire 1 according to Examples 1 to 14 can improve the stone drilling resistance of the groove 10.

DESCRIPTION OF SYMBOLS 1 pneumatic tire 2 tread part 3 tread surface 5 land part 6 chamfered part 10 groove 11 groove wall 12 groove bottom 13 opening part 14 bending part 15 1st bending part 16 2nd bending part 17 step part 18 width narrow part 21 circumference Direction groove 22 Width direction groove 25 Intersection 30 Protrusion 31 Tip 32 Side 41, 42 Circle 50 Stone

Claims (12)

A circumferential groove formed on the tread surface and extending in the tire circumferential direction;
A width direction groove formed on the tread surface and extending in the tire width direction and intersecting the circumferential direction groove;
Equipped with
In at least one of the circumferential groove and the width direction groove, the groove wall is formed to have a bent portion, and the groove width on the groove bottom side of the bent portion is the opening portion of the groove It is narrower than the groove width,
At the intersection of the circumferential groove and the width direction groove, a projection that protrudes from the bottom of the groove is provided.   The pneumatic tire according to claim 1, wherein the circumferential groove and the width direction groove have the same groove depth. The protrusions shortest distance d ₂ between the groove wall at a location within the range of 30% 0% of the height of the protrusion from the tip of the protrusion toward the groove bottom side, wherein against the groove width d ₁ at the position of the bent portion of the groove having a bent portion, the pneumatic tire according to claim 1 or 2 having at least one place a portion to be a 1.2d ₁ ≧ d _2. The protrusions shortest distance d ₂ and all of the groove walls facing the protrusion, with respect to the groove width d ₁ at the position of the bent _{portion, 0 <(d 2 / d} 1) ≦ 1 The pneumatic tire according to claim 3, which is formed within the range of .5. The height H ₁ from the groove bottom is 0.03 ≦ (H ₁ / H) with respect to the groove depth H ₀ from the bent portion of the groove having the bent portion to the groove bottom. H ₀₎ ≦ 2.0 the pneumatic tire according to claim 1 is within the range of. The height H ₁ from the groove bottom is 0.1 ≦ (H ₁ / Hg) with respect to the groove depth Hg from the opening at the position of the intersection to the groove bottom. It is in the range of ≦ 0.4, The pneumatic tire according to any one of claims 1 to 5. In the groove having the bent portion, the relationship between the groove width W _{1 of the} opening and the groove width W ₂ at a half of the groove depth is 0 <(W ₂ / W ₁ ) ≦ 0. The pneumatic tire according to any one of claims 1 to 6, which is within the range of .5.   The pneumatic tire according to any one of claims 1 to 7, wherein the bent portion is positioned in a range of 30% to 60% of the groove depth from the groove bottom toward the opening. The protrusions shortest distance d ₂ between the groove wall at the location of the range from the tip of less than 30% 0% of the height of the protrusion toward the groove bottom side of the protrusion,
Wherein in said groove having a bent portion, with respect to the minimum width d ₃ at the position of the range of the groove bottom or less 60% 30% or more toward a groove depth to the opening side, 1.2d ₃ ≧ the pneumatic tire according to claim 8 comprising at least one place a portion to be the d _2. The protrusion is
The diameter φ dp of a circle contacting the groove bottom side with respect to the bent portion in the two opposing groove walls and the protrusion.
The groove width d ₁ at the position of the bent portion of the groove having the bent portion is in the range of 0 <(φdp / d ₁ ) ≦ 1.2. The pneumatic tire according to. The protrusion is
Among the groove walls of the circumferential groove and the width direction groove, a diameter φdc of a circle in contact with the two groove walls opposed to each other across at least a part of the protrusion and the tip of the protrusion is
The present invention is in the range of 0 <(φdc / d ₄ ) ≦ 1.2 with respect to the distance d ₄ on the same plane as the circle of the facing bending portions in the groove having the bending portion. The pneumatic tire according to any one of 1 to 10. A plurality of the protrusions are provided in one of the grooves,
Distance Lp of the protrusions adjacent the relationship between the groove width d ₁ at the position of the bent portion of the groove having the bent portion (Lp / d ₁₎ ≧ 5 a is of claims 1 to 11 The pneumatic tire according to any one of the items.

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