JP5930710B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a plurality of tread patterns formed in the tire circumferential direction.

  Normally, in a pneumatic tire, the land portion formed between two circumferential grooves has a rib shape that is not divided by the lug groove, compared with a case where it is divided by the lug groove and blocked. As a result, the rigidity is increased and traveling stability on the dry road surface is ensured. On the other hand, even in the rib-shaped land portion, a lug groove that opens in one circumferential groove may be formed in order to ensure drainage (see, for example, Patent Document 1).

  However, the lug groove described above has a problem that rubber damage such as chipping or peeling starting from the lug groove (hereinafter referred to as “chunk”) is likely to occur.

JP 2009-6833

  This invention is made | formed in view of the said fact, Comprising: It aims at providing the pneumatic tire which can suppress the chunk of the lug groove formed in the tire rib.

A pneumatic tire according to a first aspect of the present invention includes a plurality of circumferential grooves formed in a tread portion and extending along a tire circumferential direction, and an outermost circumferential groove on the tire mounting outer side among the plurality of circumferential grooves. Than the tire mounting outer side, the rib having a continuous land portion in the tire circumferential direction, one end is opened in the outermost circumferential groove, and is inclined in one direction with respect to the tire width direction to the tire mounting outer side The extended other end is terminated in the rib on the outermost circumferential direction groove side than the tire ground contact end, the groove width is widened from the outermost circumferential direction groove side to the terminal end side, and the outermost circumferential direction A groove bottom on the groove side is formed between the lug groove that is shallower than the groove bottom on the terminal end side in the rib, the outermost circumferential groove and the tire ground contact end, and extends along the tire circumferential direction, and It has an intersection that intersects with the lug groove, and the groove depth is the outermost circumference. The narrow shoulder circumferential groove which is shallower than the groove depth of the lug grooves in the groove depth and the intersection of direction grooves, wherein the narrow shoulder circumferential groove has a groove wall of the lug grooves in the intersecting portion The angle of the corner between the groove wall of the shoulder circumferential narrow groove and the tread surface gradually increases in the tire circumferential direction from the acute corner of the intersecting corner with the shoulder circumferential narrow groove. The angle of the corner between the groove of the shoulder circumferential direction narrow groove and the tread is gradually decreased in the tire circumferential direction from the intersection angle of the obtuse angle among the intersection corners. It is chamfered .

In the tread portion of the pneumatic tire according to claim 1, ribs are formed on the outer side of the tire mounting when the vehicle is mounted, rather than the plurality of circumferential grooves. The rib is formed with a lug groove having one end opening in the outermost circumferential groove on the tire mounting outer side of the plurality of circumferential grooves and the other end terminating in the rib.

As described above, by forming a lug groove having one end opened in the outermost circumferential groove and the other end terminating in the rib, the drainage can be improved while ensuring the rigidity of the rib. On the other hand, the outermost groove side of the lug groove is narrower than the groove width of the terminating side, and the groove bottom rigidity is strengthened since shallower than the terminal side. Therefore, the amount of rubber movement on the outermost circumferential groove side in the rib is suppressed, distortion is reduced, and chunks starting from the lug groove can be suppressed.

A shoulder circumferential narrow groove is provided between the outermost circumferential groove and the tire ground contact edge, and the shoulder circumferential narrow groove intersects the lug groove at the intersection, thereby improving drainage while suppressing a decrease in rigidity. It is done .

By the above chamfering the corners between the groove walls and the tread surface of the shoulder circumferential narrow groove intersecting the lug groove at the intersection has been made, it is possible to suppress the chunk.

In the pneumatic tire according to claim 2 , an intersection angle portion having an acute angle among the intersection angle portions is chamfered with respect to the tread surface.

Generally, the tire circumference of the tread portion is longer as it is closer to the tire equatorial plane, and the tire contact pressure on the tire equatorial plane side is higher than the tire contact end . In the configuration of the present invention, lug grooves is, when the opening in the outermost circumferential groove comprising the tire equatorial plane side than the tire ground contact end, the groove bottom is shallower than the terminal, the outermost groove-side ribs Drag at the end is suppressed, and uneven wear at the rib end can be suppressed. Further, it is possible to form the land portion continuing in the tire circumferential direction on the tire outer peripheral end side, the rigidity is maintained in the tire outer peripheral end side, it is possible to improve the grip of the tires during effectively turning.

As described above, since the pneumatic tire of the present invention has the above-described configuration, drainage is improved , and the rubber movement on the outermost circumferential groove side in the rib on the outer side of the tire is more than the outermost circumferential groove. The amount is suppressed, distortion is reduced, and chunks starting from the lug grooves can be suppressed.

Since the pneumatic tire according to claim 2 has the above-described configuration, it is possible to suppress uneven wear at the rib ends and to effectively improve the grip force of the tire.

It is a tire radial direction sectional view of a pneumatic tire concerning this embodiment. It is a top view of the tread of the pneumatic tire concerning this embodiment. It is a partial enlarged plan view of the tread of the pneumatic tire concerning this embodiment. It is sectional drawing of the AA line of FIG. 1 is a partially enlarged perspective view of a pneumatic tire according to an embodiment. It is sectional drawing of the BB line of FIG. It is a top view of the tread of the pneumatic tire concerning the modification of this embodiment. It is a partially expanded perspective view of the pneumatic tire which concerns on the modification of this embodiment.

  Hereinafter, a pneumatic tire 10 according to an embodiment of the present invention will be described with reference to the drawings.

Note that an arrow IN in the figure indicates an inner side (inside the vehicle) in the tire width direction (hereinafter referred to as “inside the tire”) when a tire is mounted on the vehicle (hereinafter referred to as “when the tire is mounted”), and an arrow OUT indicates The outer side in the tire width direction (vehicle outer side) at the time of tire mounting (hereinafter referred to as “tire mounting outer side”) is shown. The alternate long and short dash line CL indicates the tire equator plane.

  As shown in FIG. 1, the pneumatic tire 10 of the present embodiment includes a pair of bead portions 12, a pair of sidewall portions 14, and a tread portion 16. In the bead portion 12, at least one annular bead core 12A is embedded. A carcass 18 is provided between the pair of bead cores 12A so as to straddle a toroidal shape. The carcass 18 is wound back from the inside to the outside with respect to the bead core 12A. A belt layer 19 is provided on the outer side of the carcass 18 in the tire radial direction.

  FIG. 2 shows the tread portion 16 of the pneumatic tire 10. The tire ground contact edge 16E of the tread portion 16 attaches the pneumatic tire 10 to a standard rim stipulated in JATMA YEAR BOOK (Japan Automobile Tire Association Standard, 2011 edition), and is applicable for JATMA YEAR BOOK. This is when the maximum load capacity is loaded with 100% internal pressure of the air pressure (maximum air pressure) corresponding to the maximum load capacity (bold load in the internal pressure-load capacity correspondence table) in the ply rating. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  The pneumatic tire 10 of the present embodiment has a pattern shape that is asymmetrical with respect to the tire equatorial plane CL, and is mounted so that the left side of the drawing is the tire mounting inner side and the right side of the drawing is the tire mounting outer side. The tire rotation direction is preferably mounted so that it is the direction indicated by the arrow R (the lower side in the figure is the stepping side and the upper side is the kicking side). Regarding the tire rotation direction, it is not always necessary to mount the tire with the aforementioned directionality, and the front and rear direction may be mounted in reverse.

  The tread portion 16 of the pneumatic tire 10 of the present embodiment has an innermost circumferential main groove 20 and a central circumferential main as a plurality of (three in the present embodiment) circumferential grooves extending along the tire circumferential direction. A groove 22 and an outermost circumferential main groove 24 are formed.

  The innermost circumferential main groove 20 as one circumferential groove is formed on the innermost side of the tire mounting among the three circumferential grooves. The central circumferential main groove 22 as another circumferential groove is formed on the tire mounting outer side than the innermost circumferential main groove 20 and on the tire mounting inner side than the tire equatorial plane CL. The outermost circumferential main groove 24 is formed on the tire mounting outer side than the central circumferential main groove 22 and on the tire mounting outer side than the tire equatorial plane CL.

  An inner circumferential narrow groove 26 is formed on the tire mounting inner side than the innermost circumferential main groove 20. The inner circumferential narrow groove 26 is narrower than the innermost circumferential main groove 20 and has a shallow groove depth.

  A shoulder circumferential narrow groove 28 is formed outside the outermost circumferential main groove 24 on the tire mounting outer side. The groove width W3 at the groove bottom of the shoulder circumferential narrow groove 28 is formed to be narrower than the groove width W0 of the outermost circumferential main groove 24. Further, the groove depth H3 of the shoulder circumferential narrow groove 28 is formed to be shallower than the groove depth H0 of the outermost circumferential main groove 24. The angle between the groove walls 28A and 28B constituting the shoulder circumferential narrow groove 28 and the groove bottom is larger than 90 degrees. Accordingly, the shoulder circumferential narrow groove 28 has a groove width that increases from the groove bottom toward the tread surface. The wall surface angle α (the angle between the groove bottom and the groove wall 28; see FIG. 4) of the groove wall 28A is larger on the stepping side than the kicking side, as shown in FIG. The ridgeline between 28A is inclined outward in the tire width direction from the stepping side toward the kicking side. The wall surface angle β (see FIG. 4) of the groove wall 28B is larger on the kicking side than the stepping side, and the ridge line between the fourth rib 40 and the groove wall 28B is in the tire width direction from the stepping side to the kicking side. Inclined inward.

  The shoulder circumferential narrow groove 28 is narrower than the three circumferential main grooves (the innermost circumferential main groove 20, the central circumferential main groove 22, and the outermost circumferential main groove 24). It is distinguished from the circumferential main groove in that the groove depth is shallow.

  A first rib 32 is formed between the inner circumferential narrow groove 26 and the innermost circumferential main groove 20. No groove is formed in the first rib 32. The rib width of the first rib 32 is narrower than other ribs formed on the tread portion 16.

  A second rib 34 is formed between the innermost circumferential main groove 20 and the central circumferential main groove 22. A second lug groove 36 is formed in the second rib 34. One end 36A of the second lug groove 36 opens into the innermost circumferential main groove 20 and extends from the innermost circumferential main groove 20 toward the central circumferential main groove 22 side. The other end 36 </ b> B of the second lug groove 36 does not open to the central circumferential main groove 22 and terminates in the second rib 34. Accordingly, a land portion linearly continuous in the tire circumferential direction is formed on the side of the second rib 34 close to the tire equatorial plane CL. The second lug groove 36 terminates on the tire equatorial plane CL side with respect to the center of the second rib 34 in the tire width direction. The total length L0 of the second lug groove 36 is preferably in the range of 50% to 80% of the length L of the second rib 34 in the tire width direction.

  The second lug groove 36 is slightly inclined with respect to the tire width direction. The acute angle side (upper side of the second lug groove 36 in FIG. 2) of the corners formed between the innermost circumferential main groove 20 and the second lug groove 36 is chamfered, and the chamfered portion 36M is formed. Is formed.

  As shown in FIG. 5, the second lug groove 36 has a tip portion 36 </ b> S in which the groove width W <b> 5 on the central circumferential main groove 22 side is narrower than the groove width W <b> 6 on the innermost circumferential main groove 20 side. The distal end portion 36S is configured to be narrow by forming an R step portion 36D as a groove width changing portion in the groove wall on the side where the chamfered portion 36M is not formed. The R step portion 36D has a curved shape with a smooth connection corner from the tip portion 36S. The groove bottom of the second lug groove 36 is deepest on the innermost circumferential main groove 20 side, and gradually becomes shallower toward the tip 36S side.

  The length L1 of the distal end portion 36S is preferably about 20% to 50% of the entire length L0 of the second lug groove 36. Further, the groove width W5 (the groove width W5 on the central circumferential main groove 22 side) of the distal end portion 36S is preferably about 20% to 60% of the groove width W6 on the one end 36A side of the second lug groove 36.

  A third rib 38 is formed between the central circumferential main groove 22 and the outermost circumferential main groove 24. The tire equatorial plane CL is disposed on the central circumferential main groove 22 side on the third rib 38. A sipe 38S is formed on the third rib 38. The sipe 38S opens to the outermost circumferential main groove 24 and extends from the outermost circumferential main groove 24 toward the central circumferential main groove 22 side. The sipe 38S has a groove width that is closed by grounding. The groove walls constituting the sipe 38S are chamfered along the sipe 38S to form chamfered portions 38A and 38B. The sipe 38 </ b> S does not open to the central circumferential main groove 22 and terminates in the third rib 38. Therefore, a land portion that is linearly continuous in the tire circumferential direction is formed on the end portion of the third rib 38 on the side close to the tire equatorial plane CL.

  A fourth land portion 40 is formed between the outermost circumferential main groove 24 and the shoulder circumferential narrow groove 28. Further, an outer rib 46 is formed on the tire grounding end 16E side on the outer side of the tire from the fourth land portion 40. The fourth land portion 40 is formed with a fourth lug groove 42 extending from the outermost circumferential main groove 24 toward the tire mounting outer side. The fourth lug groove 42 is linear, one end 42A is opened in the outermost circumferential main groove 24, crosses the shoulder circumferential narrow groove 28, and the other end (hereinafter, this other end is referred to as "terminal portion 42B"). ) Extends into the outer rib 46. One end 42A of the fourth lug groove 42 is disposed as an extension of the sipe 38S. Further, the fourth lug groove 42 is inclined in the same direction as the sipe 38 </ b> S, and constitutes a design that is continuous with the sipe 38 </ b> S via the outermost circumferential main groove 24.

  The fourth lug groove 42 intersects the shoulder circumferential narrow groove 28 and terminates at a terminal portion 42 </ b> B in the outer rib 46. The end portion 42B is disposed closer to the tire equatorial plane CL than the tire ground contact end 16E on the tire mounting outer side. The outer rib 46 has a land portion that continues linearly in the tire circumferential direction. As shown also in FIG. 3, the groove width of the fourth lug groove 42 is W1 that is the narrowest at one end 42 </ b> A that is an opening portion to the outermost circumferential main groove 24, and at the end portion 42 </ b> B in the outer rib 46. W2 is the widest. The fourth lug groove 42 is formed so as to gradually expand from the one end 42A toward the terminal end 42B.

  As shown in FIG. 4, the groove depth H4 of the fourth lug groove 42 is shallower than the groove depth H0 of the outermost circumferential main groove 24 and deeper than the groove depth H3 of the shoulder circumferential narrow groove 28. It has become. At the intersection 45 where the fourth lug groove 42 and the shoulder circumferential narrow groove 28 intersect (see FIG. 2), the groove depth is H4. Accordingly, the bottom of the shoulder circumferential narrow groove 28 is deeper than the other portions of the shoulder circumferential narrow groove 28 at the intersection 45. In FIG. 4, the tire ground contact surface is schematically shown as a plane in order to facilitate comparison of groove depths.

  As shown in FIG. 6, a groove bottom upper portion 44 in which the groove is raised is formed on the one end 42 </ b> A side of the fourth lug groove 42. The groove depth H5 of the groove bottom upper portion 44 is shallower than the groove depth H4 of the fourth lug groove 42, and the groove bottom upper portion 44 is formed from one end 42A to the vicinity of the center of the fourth land portion 40. In FIG. 6 as well, the tire ground contact surface is schematically shown as a plane in order to facilitate comparison of the groove depth.

  In the fourth land portion 40 and the outer rib 46, an acute angle side (hereinafter referred to as an acute angle corner portion) of the corner portions of the intersecting portion 45 formed between the fourth lug groove 42 and the shoulder circumferential narrow groove 28. Chamfered portions 40M and 46M are respectively formed on the corner portion on the obtuse angle side (referred to as "acute angle portion 40A" and the obtuse angle portion 40B).

  A wear indicator 48 is formed on the extended portion of the outer rib 46 from the fourth lug groove 42. The wear indicator 48 is composed of two holes formed apart from the terminal end portion 42B of the fourth lug groove 42. With this wear indicator 48, the wear state of the outer rib 46 can be known separately from the wear indicator normally provided in the tire circumferential main groove.

  Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.

  In the pneumatic tire 10 of the present embodiment, the innermost circumferential main groove 20, the central circumferential main groove 22, and the outermost circumferential main groove 24 are formed in the tread portion 16, so that basic drainage is performed. , Straight running stability during dry and wet running.

  Further, on the tread portion 16 of the pneumatic tire 10 of the present embodiment, an outer rib 46 having a land portion continuous in the tire circumferential direction is disposed on the tire mounting outer side. Accordingly, the rigidity on the outer side of the tire is ensured and the cornering performance can be enhanced. Further, the fourth lug groove 42 extending to the outer rib 46 terminates without reaching the tire ground contact end 16E. Therefore, the rigidity of the outer rib 46 can be effectively ensured. Further, the groove width of the fourth lug groove 42 is the maximum W2 in the outer rib 46. As a result, water on the outer rib 46 side can be captured and flowed to the outermost circumferential main groove 24 at a portion where the groove width is wide, and drainage on the outer rib 46 side can be improved.

  The fourth lug groove 42 has a groove bottom upper portion 44 on the one end 42A side. Therefore, the rigidity of the fourth land portion 40 can be maintained while ensuring the drainage. The groove bottom upper part 44 is formed on the one end 42A side. Therefore, the groove depth on the tire mounting outer side is ensured, and more water can be captured on the tire mounting outer side.

  In the pneumatic tire 10 of the present embodiment, the shoulder circumferential narrow groove 28 is formed adjacent to the outer rib 46. Therefore, the outer rib 46 can be drained by the shoulder circumferential narrow groove 28, and drainage can be improved. On the other hand, the shoulder circumferential narrow groove 28 is narrower than the outermost circumferential main groove 24 and narrower than the outermost circumferential main groove 24 and the fourth lug groove 42. Therefore, a decrease in rigidity of the outer rib 46 can be suppressed.

  Further, by forming the shoulder circumferential narrow groove 28, buckling during cornering can also be suppressed. Buckling here is a phenomenon in which the tread surface floats off the road surface and the ground pressure inside the tire is released while the tire is about to fall outside with the fulcrum near the outside edge of the tire when cornering. . In the pneumatic tire 10 of the present embodiment, since the shoulder circumferential narrow groove 28 is formed, the bending rigidity of the tread surface is lowered, so that the tire mounting inner side, particularly the land portion 40 is easily grounded, and the tire It is possible to suppress a decrease in grip strength inside the mounting.

  Further, in the present embodiment, since the sipe 38S is formed on the third rib 38, it is possible to suppress uneven wear at the rib end of the third rib 38 on the side far from the tire equatorial plane CL. That is, in the third rib 38, since the rib end on the outermost circumferential main groove 24 side is far from the tire equatorial plane CL, the tire circumferential length becomes short and dragging easily occurs. In other words, since the sipe 38S is formed, drag is suppressed and uneven wear can be suppressed. Moreover, since the sipe 38S does not open to the central circumferential main groove 22, a land portion that is linearly continuous in the tire circumferential direction is formed. Therefore, in the third rib 38, rigidity on the side close to the tire equatorial plane CL is ensured, and steering stability can be maintained. Further, since the chamfered portions 38A and 38B are formed along the sipe 38S, chunks such as chipping or peeling of the rubber around the sipe 38S in the tire circumferential direction can be suppressed.

  Moreover, in this embodiment, since the 2nd lug groove 36 is formed in the 2nd rib 34, drainage property can be improved. Further, the second lug groove 36 has a narrower groove width toward the tire equatorial plane CL side and a shallower groove depth, so that the rigidity on the higher contact pressure side is maintained and the occurrence of chunks is suppressed. be able to. Moreover, since the chamfered portion 36M is formed on the acute angle side of the corner portion formed between the innermost circumferential main groove 20 and the second lug groove 36, chunks at the corner portion can be suppressed. it can. Further, the second lug groove 36 is opened in the innermost circumferential main groove 20 on the side far from the tire equatorial plane CL. In general, the tire circumferential length of the tread portion is longer as it is closer to the tire equatorial plane CL, and the tire contact pressure is higher. Therefore, dragging at the rib end of the second rib 34 on the side far from the tire equatorial plane is suppressed, and uneven wear can be suppressed. Further, since the second lug groove 36 does not open to the central circumferential main groove 22, a land portion linearly continuous in the tire circumferential direction is formed at the rib end on the central circumferential main groove 22 side. Therefore, rigidity is ensured on the side close to the tire equatorial plane CL, and steering stability can be maintained.

  Further, in the present embodiment, the chamfered portions 40M and 46M are respectively formed on the acute angle portion 40A on the side of the acute angle among the corner portions of the intersecting portion 45 formed between the fourth lug groove 42 and the shoulder circumferential narrow groove 28. Is formed. Therefore, chunks such as chipping or peeling of rubber at the corners can be suppressed.

  In the present embodiment, the groove width W1 on the one end 42A side of the fourth lug groove 42 is wider than the groove width W2 of the terminal end portion 42B. However, it is not always necessary to do this, and the groove widths W1 and W2 are not necessarily required. Or a configuration in which the groove width W1 is wider than W2.

  Further, in the present embodiment, the shoulder circumferential narrow groove 28 is formed, but a configuration without the shoulder circumferential narrow groove 28 may be adopted.

  Further, in the present embodiment, the configuration in which the fourth lug groove 42 intersects the shoulder circumferential narrow groove 28 and reaches the outer rib 46 has been described, but the fourth lug groove 42 is not necessarily the shoulder circumferential narrow groove 28. There is no need to cross. As shown in FIG. 7, it may be configured such that it only opens in the shoulder circumferential narrow groove 28 and does not protrude toward the outer rib 46 side. Moreover, you may make it the structure which terminates in the 4th land part 40 before the shoulder circumferential direction fine groove 28. FIG.

  In each of the above embodiments, the fourth lug groove 42 is inclined with respect to the tire width direction. However, the fourth lug groove 42 is not necessarily inclined with respect to the tire width direction. You may arrange | position in parallel with a direction.

  Further, in the present embodiment, the chamfered portion 36M is formed on the acute angle side of the corner portions formed between the innermost circumferential main groove 20 and the second lug groove 36, but as shown in FIG. It is good also as a structure without the chamfering part 36M.

  In the present embodiment, a left-right asymmetric tread pattern has been described as an example. However, the present invention may be applied to a left-right symmetrical tread pattern.

10 Pneumatic tire 16E Tire contact point 16 Tread portion 20 Innermost circumferential main groove (one circumferential groove)
22 Central circumferential main groove (other circumferential grooves)
34 Second rib (rib)
36 Third lug groove (lug groove)
36A One end 36B The other end 36D Stepped part (groove width changing part)
36M Chamfer

Claims (2)

A plurality of circumferential grooves formed in the tread portion and extending along the tire circumferential direction;
Of the plurality of circumferential grooves, a rib that is disposed on the tire mounting outer side than the outermost circumferential groove on the tire mounting outer side, and the land portion continues in the tire circumferential direction,
One end is opened in the outermost circumferential groove, and the other end that is inclined in one direction with respect to the tire width direction and extends to the tire mounting outer side is in the rib on the outermost circumferential groove side than the tire ground contact end. A lug groove that has a groove width that is widened from the outermost circumferential direction groove side toward the terminal end side, and whose groove bottom on the outermost circumferential direction groove side is shallower than the groove bottom on the terminal end side in the rib When,
A groove depth is formed between the outermost circumferential groove and the tire ground contact edge, extends along the tire circumferential direction and intersects the lug groove, and the groove depth is the groove depth of the outermost circumferential groove. And a shoulder circumferential direction narrow groove made shallower than the groove depth of the lug groove at the intersection,
Equipped with a,
The shoulder circumferential direction narrow groove is a groove wall of the shoulder circumferential direction narrow groove from an intersection angle part having an acute angle among the intersection angle parts of the groove wall of the lug groove and the shoulder circumferential direction narrow groove at the intersection. Chamfered so that the angle of the corner portion between the tire and the tread surface gradually increases in the tire circumferential direction, and the shoulder circumferential direction narrow groove groove and the tread surface from the intersecting corner portion having an obtuse angle among the intersecting corner portions A pneumatic tire chamfered so that the angle of the corner portion between the tire and the tire gradually decreases in the tire circumferential direction . The pneumatic tire according to claim 1, wherein an intersection angle portion having an acute angle among the intersection angle portions is chamfered with respect to the tread surface .

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