JP2016068615A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that can further suppress uneven wear of a land part and further improve wet brake performance.SOLUTION: A plurality of dents 32 are provided at intervals along a circumferential direction of a tire on a first land part 22 partitioned with a circumferential groove. The dents 32 include a first dent part 36 that assumes an oblong shape in a plan view of a tread, and a second dent part 34 that is formed adjacently to the first dent part 36 and formed more deeply than the first dent part 36. A major axis of the oblong shape is inclined with respect to the circumferential direction of the tire.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire having a tread with land portions partitioned by a plurality of grooves.

  There has been proposed a pneumatic tire in which a tread is provided with a land portion in which a plurality of depressions are formed (see Patent Documents 1 and 2).

JP 2009-67180 A. Japanese Patent No. 2009-67181.

  In a pneumatic tire having a tread with a land portion in which a plurality of depressions are formed, it is required to suppress uneven wear of the land portion and ensure wet brake performance.

  An object of the present invention is to provide a pneumatic tire that can further suppress uneven wear of a land portion and further improve wet brake performance.

  The pneumatic tire according to claim 1 is provided with a land portion provided in a tread and partitioned by a plurality of grooves, and provided in the land portion with an interval in a tire circumferential direction, and has an oval shape in a plan view of the tread. And a second depression formed integrally with the first depression and formed deeper than the first depression. An oblong major axis is in the tire circumferential direction. And a plurality of depressions that are inclined with respect to each other.

  In the pneumatic tire according to claim 1, since a plurality of grooves are formed in the tread, when running on a wet road surface, water between the tread and the road surface is taken into the groove and drained, so that basic wet brake performance is achieved. Can be obtained. In the land portion, a plurality of depressions are arranged at intervals along the tire circumferential direction, so that water between the land portion and the road surface can be taken into the depression when running on a wet road surface. Since the water film between the land portion and the road surface can be cut at the edge, the water film is excellent in water removal and the wet brake performance can be improved. Since the long axis of the oval is inclined with respect to the tire circumferential direction, the depression has an edge component in the tire width direction (the length of the edge projected in the tire circumferential direction) compared to a perfect circular depression with the same area. ) Becomes longer, the wet brake performance can be further improved. Moreover, since the hollow is comprised including the 1st hollow part and the 2nd hollow part provided integrally with the 1st hollow part and formed deeper than the 1st hollow part, the 1st hollow part is comprised. The capacity to take up water can be increased compared to the case of only the case. If the bottom is made flat and the entire depression is deeply formed, the volume of the depression increases, but the surrounding rigidity may be lowered.

  In addition, since a plurality of depressions are arranged at intervals in the tire circumferential direction in the land portion, the rigidity of the land portion in the tire circumferential direction is ensured, while the compression rigidity is appropriately reduced, and the rigidity of the land portion is also ensured. Can be made uniform, and uneven wear can be suppressed by comparison with the land portion where no depression is formed.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the first recess is gradually from the end side in the direction along the minor axis of the ellipse toward the major axis. It is deeper.

  In the pneumatic tire according to claim 2, the second depression is gradually deepened from the end side in the direction along the minor axis of the ellipse toward the major axis. When the water between the first land part and the road surface moves in the tire width direction and is taken into the depression, there is no sudden volume change along the water flow, Disturbance can be suppressed. For this reason, the water between a 1st land part and a road surface can be removed effectively.

  According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect of the invention, the first recess is formed in the oval shape from the end side in the direction along the major axis of the oval shape. It gradually becomes deeper toward the short axis.

  In the pneumatic tire according to claim 3, the first depression is gradually deepened from the end side in the direction along the major axis of the ellipse toward the minor axis, so that the input in the tire circumferential direction is performed. When the water between the first land portion and the road surface moves in the tire circumferential direction and is taken into the depression, there is no sudden volume change along the water flow, Disturbance can be suppressed. For this reason, the water between a 1st land part and a road surface can be removed effectively.

  According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the first hollow portion is an end portion side in a direction along the major axis of the oval shape. To gradually toward the bottom of the second recess.

  In the pneumatic tire according to claim 4, the first depression is gradually deeper from the end side in the direction along the major axis of the oval shape toward the bottom of the second depression. It becomes easy for the water taken in into the depression to flow toward the bottom of the second depression.

  According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects, the first recess portion has a width toward the outer side in the vehicle width direction when the vehicle is mounted. Is narrower.

  In the pneumatic tire according to claim 5, since the width of the first recess is narrower toward the outside in the vehicle width direction, the contact area becomes wider toward the outside in the vehicle width direction around the recess, The rigidity of the recess outside in the vehicle width direction can be increased. For this reason, when the input from the vehicle width direction outer side acts, it can suppress that the edge part of a hollow falls, and can ensure a ground-contact area effectively.

  A sixth aspect of the present invention is the pneumatic tire according to any one of the first to fifth aspects, wherein the second dent portion is a vehicle width of the first dent portion when the vehicle is mounted. It is provided inside the direction.

  In the pneumatic tire according to claim 6, since the second dent portion is provided on the inner side in the vehicle width direction of the first dent portion, the rigidity around the dent is equal to the rigidity on the outer side of the dent in the vehicle width direction. It becomes higher than the rigidity inside the direction. When a vehicle equipped with a pneumatic tire corners, the pneumatic tire placed radially outside the cornering is loaded more than the pneumatic tire placed radially inside the cornering due to the action of centrifugal force. The burden increases. Further, an input from the outside in the vehicle width direction when the vehicle is mounted acts on the tread of the pneumatic tire disposed outside the radius of the cornering. When an input from the vehicle width direction outer side acts on the depression formed in the land portion, the edge of the depression on the vehicle width direction outer side is dragged to the road surface and becomes easy to droop. However, in the pneumatic tire according to claim 5, the rigidity around the depression in the land portion is higher than the rigidity in the vehicle width direction outside of the depression (the second depression having a deep depth). Since the rigidity of the periphery of the recess is relatively lower than the periphery of the first recess with a shallow depth), curling of the outer edge of the recess in the vehicle width direction is suppressed, and thereby sufficient grounding of the land An area is ensured, and a grip force on a wet road surface and a dry road surface can be secured.

  The invention according to claim 7 is the pneumatic tire according to any one of claims 1 to 6, wherein the recess is provided on the shoulder side on the inner side in the vehicle width direction of the tread. Is formed.

  By disposing a land portion provided with a depression on the shoulder side of the tread in the vehicle width direction, the rigidity on the shoulder side of the tread in the vehicle width direction can be increased. This makes it suitable for a vehicle that is desired to be fitted with a pneumatic tire in which the rigidity of the tread on the inner side in the vehicle width direction is important.

  As described above, according to the pneumatic tire of the present invention, there is an excellent effect that the uneven wear of the land portion can be further suppressed and the wet brake performance can be further improved.

It is a top view showing the tread of the pneumatic tire concerning one embodiment of the present invention. (A) is an enlarged plan view showing a dent, (B) is a sectional view taken along line 2B-2B of the dent shown in FIG. 2 (A), and (C) is a 2C- of the dent shown in FIG. 2 (A). It is 2C sectional view. (A)-(D) are the enlarged plan views which show the hollow which concerns on other embodiment.

  A pneumatic tire 10 according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the tread 12 of the pneumatic tire 10 of the present embodiment has a first circumferential groove 14 extending along the tire circumferential direction (arrow A direction and arrow B direction) on the arrow IN direction side. The second circumferential groove 16, the third circumferential groove 18, and the fourth circumferential groove 20 are formed in this order on the arrow OUT direction side of the first circumferential groove 14. In the drawings, the arrow IN direction indicates the inner side in the vehicle width direction when the pneumatic tire 10 is mounted on the vehicle, and the arrow OUT direction indicates the vehicle width direction outer side when the pneumatic tire 10 is mounted on the vehicle. Indicates the direction. The pneumatic tire 10 of the present embodiment is designated with the mounting direction of the vehicle inner side and the vehicle outer side when the vehicle is mounted, and a mark (not shown) indicating the direction when the vehicle is mounted is given to the side surface. Yes. In FIG. 1, reference numeral 12 </ b> E indicates an end portion of the tread 12.

  The tread 12 has a first land portion 22 and a second land portion 20 from the right side of the drawing by the first circumferential groove 14, the second circumferential groove 16, the third circumferential groove 18, and the fourth circumferential groove 20. A section 24, a third land section 26, a fourth land section 28, and a fifth land section 30 are defined. The first land portion 22 is disposed on the shoulder side of the tread 12 in the arrow IN direction, and the fifth land portion 30 is disposed on the shoulder side of the tread 12 in the arrow OUT direction.

  A plurality of depressions 32 are arranged in a staggered manner along the tire circumferential direction in the first land portion 22. As shown in FIGS. 2 (A) and 2 (B), the dent 32 is formed in a first dent part 36 that has an oval shape (substantially elliptical shape) in plan view of the tread, and a bottom part of the first dent part 36. And a second depression 34 that is circular in a plan view of the tread, and a second depression 34 that is deeper than the first depression 36 is integrated with the first depression 36 on the arrow IN direction side. Is formed. The depth of the second recess 34 is shallower than the first circumferential groove 14, the second circumferential groove 16, the third circumferential groove 18, and the fourth circumferential groove 20, but at the end of wear of the tread 12. The depth is set to remain.

  By the way, an “ellipse” is a curve formed from a set of points such that the sum of distances from two fixed points on a plane is constant in terms of geometry. The “ellipse (substantially oval)” is a shape in which a plurality of circular arcs having different curvature radii are connected in a ring shape.

  The major axis direction of the oval shape in the first recess 36 is inclined with respect to the tire circumferential direction. The tread planar view shape of the first recess portion 36 of the present embodiment has a semicircular shape at the end on the arrow IN direction side, the width gradually decreases toward the arrow OUT direction side, and the end on the arrow OUT direction side. The part has a semicircular shape with a smaller radius of curvature than the end on the arrow IN direction side.

  As shown in FIG. 2A and FIG. 2B, the first dent portion 36 extends from the end (edge portion of the opening) on the arrow OUT direction side in the longitudinal direction (long axis direction) to the second dent portion. The bottom part of the 2nd hollow part 34 and the deepest part of the bottom part of the 1st hollow part 36 are smoothly connected with the curved surface. As shown in FIGS. 2A and 2C, the first recess 36 is directed from the end (edge of the opening) on the width direction side (short axis direction side) toward the center in the width direction. It is gradually formed deeper (toward the long axis of the ellipse), and the cross-sectional shape of the bottom is a substantially arc shape. In addition, a long axis is an axis | shaft which points to the largest dimension of an ellipse shape. The short axis is an axis in a direction intersecting with the long axis.

  As shown in FIG. 1, a plurality of fine grooves 38 extending along the tire circumferential direction are formed in the first land portion 22 on the arrow OUT direction side of the recess 32 at intervals in the tire circumferential direction. In addition, a sipe 40 extending from one end of the narrow groove 38 on the arrow A direction side to the arrow OUT direction side is formed.

  A plurality of first sipes 42 that cross the second land portion 24 in the tire width direction are arranged in the second land portion 24 at intervals in the tire circumferential direction. Further, a notch 44 is formed between the first sipe 42 and the first sipe 42 at the end of the second land portion 24 on the arrow OUT direction side. Further, the second land portion 24 extends between the first sipe 42 and the first sipe 42 from the arrow IN direction side to the arrow OUT direction, terminates in the land portion, and is not connected to the notch 44. A sipe 46 is formed.

  In the third land portion 26, a plurality of sipes 48 that cross the third land portion 26 in the tire width direction are arranged at intervals in the tire circumferential direction, and at the end on the arrow IN direction side, A groove 50 extending from the arrow IN direction side to the arrow OUT direction side and terminating in the land portion is formed.

  In the fourth land portion 28, a plurality of lateral grooves 52 that cross the fourth land portion 28 in the tire width direction are arranged at intervals in the tire circumferential direction, and between the lateral grooves 52 and the lateral grooves 52. Is formed with a groove 54 extending from the arrow IN direction side to the arrow OUT direction side and terminating in the land portion at the end of the arrow IN direction side.

  In the fifth land portion 30, lateral grooves 56 extending from the end on the arrow OUT direction side toward the arrow IN direction side are arranged at intervals in the tire circumferential direction, and on the arrow IN direction side of the lateral groove 56. Sipes 58 extending from the end portion toward the end of the fifth land portion 30 on the arrow IN direction side are provided at every other lateral groove 56.

(Action / Effect)
Next, the operation and effect of the pneumatic tire 10 of the present embodiment will be described.
In the pneumatic tire 10 of the present embodiment, the plurality of depressions 32 are arranged in the first land portion 22 in a staggered manner at a constant interval in the tire circumferential direction. While ensuring the rigidity, the compression rigidity can be appropriately reduced and the rigidity of the first land portion 22 can be made uniform. Thereby, the partial wear of the 1st land part 22 can be controlled. In addition, since the depression 32 does not excessively reduce the rigidity of the land portion compared to the groove, the rigidity necessary for the first land portion 22 can be ensured.

  Moreover, since the groove | channel which crosses the 1st land part 22 in the tire width direction is not formed in the 1st land part 22, compared with the case where this groove | channel is formed, high land part rigidity is acquired. ing. Therefore, the rigidity of the tread 12 in the direction of the arrow IN, that is, the inner side in the vehicle width direction when the vehicle is mounted can be secured, and the pneumatic tire in which the rigidity in the vehicle width direction when the tread 12 is mounted is emphasized. This is suitable for a vehicle such as a minivan for which it is desired to mount 10.

  The depression 32 can take in water between the first land portion 22 and the road surface when traveling on a wet road surface, and can cut a water film between the first land portion 22 and the road surface at the edge portion of the depression 32. Therefore, the water film is excellent in water removal performance, and the wet brake performance can be improved. Further, the recess 32 has an oval shape in plan view of the tread, and the major axis of the ellipse is inclined with respect to the tire circumferential direction, so that the edge in the tire width direction is compared to a perfect circle recess having the same area. Since the component (the length of the edge projected in the tire circumferential direction) becomes longer, the wet brake performance can be further improved.

  In addition, in order to lengthen the edge component in the tire width direction, when the length of the first hollow portion 36 having an oval shape is A and the width of the first hollow portion 36 is B (FIG. 2A). Reference) and A / B are preferably set in the range of 1.3 to 3.0. When A / B is less than 1.3, the shape of the recess 32 in plan view is close to a perfect circle, and the edge component projected in the tire circumferential direction is insufficient. On the other hand, when A / B exceeds 3.0, the dent 32 becomes too long and becomes a groove shape, which may reduce the rigidity of the first land portion 22 more than necessary.

The depression 32 includes a first depression 36 and a second depression 34 provided integrally with the first depression 36 and formed deeper than the first depression 36. Compared to the case of only one depression 36, the volume of water taken in can be increased. In addition, when the bottom is flat and the entire depression 32 is formed deep, the volume of the depression 32 increases, but the rigidity of the surroundings may be reduced.
The first recess 36 is gradually deepened from the end on the arrow OUT direction side toward the second recess 34 when viewed in a cross section along the major axis direction of the ellipse, and therefore the arrow OUT When the water between the land portion 22 and the road surface moves from the arrow OUT direction side to the arrow IN direction side and is taken into the first recess portion 36 by the input from the direction side, the volume of the first recess portion 36 is Therefore, the water between the first land portion 22 and the road surface can be effectively removed while the disturbance of the water flow is suppressed. By removing the water in the contact surface, the contact property is improved and the wet brake performance is improved.

  In addition, the first dent portion 36 has a width direction center of the first dent portion 36 from both ends in the width direction of the first dent portion 36 (edges of the opening on both sides in the short axis direction of the ellipse), that is, an oval shape. Since the depth gradually increases toward the major axis, the depth gradually increases from the edge of the opening on the tire circumferential direction side of the first recess 36 toward the major axis of the ellipse. For this reason, when the water between the land portion 22 and the road surface moves in the tire circumferential direction and is taken into the first depression 36 by the circumferential input, the direction of the water flow does not change abruptly. The water between the first land portion 22 and the road surface can be effectively removed while suppressing disturbance of the water flow. By removing the water in the contact surface, the contact property is improved and the wet brake performance is improved.

  In this embodiment, the tread planar shape of the depression 32 is narrower on the arrow OUT direction side than on the arrow IN direction side, and around the depression 32, the arrow OUT direction from the arrow IN direction side of the depression 32 The ground contact area becomes wider toward the direction side. For this reason, the ground contact area can be secured on the arrow OUT direction side of the recess 32, and the rigidity of the recess 32 on the arrow OUT direction side can be increased. By ensuring both rigidity and improvement of the ground contact surface, it is possible to improve grip when cornering on dry road surfaces and wet road surfaces.

  When the vehicle corners, a large lateral input acts on the pneumatic tire 10 mounted on the outer side in the vehicle width direction. During cornering, input from the arrow OUT direction side acts on the first land portion 22, but the rigidity of the recess 32 on the arrow OUT direction side is increased, so the end portion of the recess 32 on the arrow OUT direction side is increased. As a result, the contact area of the first land portion 22 can be effectively secured. By ensuring both rigidity and improvement of the ground contact surface, it is possible to improve grip when cornering on dry road surfaces and wet road surfaces.

  Further, the recess 32 is formed in an oval shape in a tread plan view, and since there is no corner, it is difficult for stress to concentrate and generation of cracks and the like can be suppressed. In addition, the ground contact property of the recess portion edge is improved and the wear resistance is also improved by suppressing the stress concentration.

[Other Embodiments]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and other various modifications can be made without departing from the spirit of the present invention. It is.

  In the dent 32 of the above embodiment, the circular second dent 34 is formed on the arrow IN direction side of the oval first dent 36, but the present invention is not limited to this. The shape shown in FIGS. 3A to 3D may be used. The recess 32 shown in FIG. 3 (A) has a circular second recess 34 formed in the center of the first oval first recess 36. The recess 32 shown in FIG. A circular second recess 34 is formed in the center of the first recess 36 of the circle. The recess 32 shown in FIG. 3C has an oval second recess 34 formed on one end side of the oval first recess 36, and the recess 32 shown in FIG. An oblong first recess 34 is formed at the center of the second recess 36. Further, the shape of the recess 32 when the tread 12 is viewed in plan is not limited to the shape shown in FIGS. 1 and 3A to 3D, and may be an oval shape formed by a curve without corners. .

  The depression 32 only needs to have an elliptical long axis that is inclined with respect to the tire circumferential direction, and the long axis may be 90 degrees with respect to the tire circumferential direction. It may be inclined. In any case, the length of the edge projected in the tire circumferential direction of the recess 32 only needs to be longer than the length projected in the tire width direction.

In the said embodiment, although the hollow 32 was formed in the 1st land part 22, this invention is not restricted to this, The 2nd land part 24, the 3rd land part 26, the 4th land part 28, And you may form in the 5th land part 30.
In the above embodiment, the depressions 32 are arranged in a staggered manner along the tire circumferential direction, but may be arranged in a straight line along the tire circumferential direction, and the rows of depressions 32 arranged in the tire circumferential direction. May be arranged in a plurality of rows in the tire width direction.

  In the said embodiment, although the hollow 32 was formed in the rib-shaped 1st land part 22 extended in a tire circumferential direction, this invention is not limited to this, The block-shaped partitioned by the circumferential groove | channel and the lateral groove | channel. It may be formed in the land part, and the shape of the land part in which the depression 32 is provided is not limited.

DESCRIPTION OF SYMBOLS 10 ... Pneumatic tire, 12 ... Tread, 14 ... 1st circumferential groove, 22 ... 1st land part (land part), 32 ... Depression, 34 ... 2nd Hollow part, 36 .. first hollow part

Claims (7)

A land portion provided in the tread and partitioned by a plurality of grooves;
A first recess that is provided in the land portion with an interval in the tire circumferential direction and has an oval shape in a tread plan view, and is provided integrally with the first recess and deeper than the first recess. A plurality of dents that are configured to include the formed second dent part, and whose ellipse-shaped major axis is inclined with respect to the tire circumferential direction;
Pneumatic tire having   2. The pneumatic tire according to claim 1, wherein the first recess portion is gradually deeper from an end side in a direction along an elliptical minor axis toward the major axis.   3. The air according to claim 1, wherein the first recess portion is gradually deepened from an end side in a direction along the major axis of the ellipse toward the minor axis of the ellipse. Enter tire.   The said 1st hollow part is any one of Claims 1-3 which becomes gradually deep toward the bottom part of the said 2nd hollow part from the edge part side of the direction along the ellipse long axis. The pneumatic tire according to item.   The pneumatic tire according to any one of claims 1 to 4, wherein the first recess portion has a width that decreases toward the outside in the vehicle width direction when the vehicle is mounted.   The pneumatic tire according to any one of claims 1 to 5, wherein the second depression is provided on an inner side in the vehicle width direction of the first depression when the vehicle is mounted.   The pneumatic tire according to any one of claims 1 to 6, wherein the recess is formed in the land portion provided on a shoulder side on the inner side in the vehicle width direction of the tread.

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