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US-12617241-B2 - Tire

US12617241B2US 12617241 B2US12617241 B2US 12617241B2US-12617241-B2

Abstract

A tire, in which a groove width that opens to a road contact surface of a tread portion is greater than 1.0 mm and 4.0 mm or less, includes: one or more circumferential narrow grooves extending in a tire circumferential direction; and a plurality of sipes communicating with the circumferential narrow groove. The circumferential narrow groove includes: a widened portion provided in a region in which a groove depth from the surface of the tread portion is 30% or more of a maximum groove depth and having a widened groove width; and a plurality of notch portions provided at intervals in the tire circumferential direction to bulge toward one side in a tire width direction to communicate from the surface of the tread portion to the widened portion. The sipes are connected to the notch portions.

Inventors

  • Hideki Nagasawa

Assignees

  • THE YOKOHAMA RUBBER CO., LTD.

Dates

Publication Date
20260505
Application Date
20210923
Priority Date
20200930

Claims (15)

  1. 1 . A tire, comprising: one or more circumferential narrow grooves extending in a tire circumferential direction and having a groove width of an opening portion open to a surface of a tread portion being greater than 1.0 mm and 4.0 mm or less; and a plurality of width-direction sipes communicating with the one or more circumferential narrow grooves from both sides in a tire width direction of the one or more circumferential narrow groove, at least one of the one or more circumferential narrow grooves comprising: a widened portion provided in a region in which a groove depth from the surface of the tread portion is 30% or more of a maximum groove depth and having a groove width wider than the opening portion; and a plurality of notch portions provided at intervals in the tire circumferential direction to bulge toward only one side in the tire width direction to communicate from the surface of the tread portion to the widened portion, and the width-direction sipe being connected to at least one of the notch portions; wherein a number of the notch portions provided in one of the one or more circumferential narrow grooves is 10 or more and 20 or less in a ground contact surface of the tread portion, a number of the width-direction sipes communicating with the one of the one or more circumferential narrow grooves from one side in the tire width direction is different than a number of the width-direction sipes communicating with the one of the one or more circumferential narrow grooves from an other side in the tire width direction, along an entire circumference of the tire, a number of the width direction sipes on one side of a tire equatorial plane is the same as a number of the width direction sipes on an opposite side of the tire equatorial plane, and a pitch of the width-direction sipes communicating with the one of the one or more circumferential narrow grooves from the one side in the tire width direction is P and a pitch of the width-direction sipes communicating with the one of the one or more circumferential narrow grooves from the other side in the tire width direction is P/2.
  2. 2 . The tire according to claim 1 , wherein an opening area of each of the notch portions in the surface of the tread portion is 1.5 mm 2 or more and 10.0 mm 2 or less.
  3. 3 . The tire according to claim 1 , wherein a width Wa of each of the notch portions and a groove width W 1 of the opening portion are in a range of 0.5≤(Wa/W 1 )≤2.0.
  4. 4 . The tire according to claim 1 , wherein a ratio of a number of the notch portions bulging toward an inner side to a number of the notch portions bulging toward an outer side in the tire width direction of the at least one of the circumferential narrow grooves, among the notch portions provided in the at least one of the circumferential narrow grooves, is 0.2 or more and 1.0 or less.
  5. 5 . The tire according to claim 1 , wherein a maximum groove width W 2 of the widened portion and a groove width W 1 of the opening portion are in a range of 1.0<(W 2 /W 1 )≤4.0, and a width Wb from the opening portion to the widened portion and a width Wa of each of the notch portions are in a range of 0.5≤(Wa/Wb)≤2.0.
  6. 6 . The tire according to claim 1 , wherein a groove depth H 4 of the width-direction sipe satisfies a relationship of H 3 <H 4 <0.9 H 1 , with respect to: a depth H 3 from the surface of the tread portion in the at least one of the circumferential narrow grooves to a connection portion between one of the notch portions and the widened portion; and the maximum groove depth H 1 of the at least one of the circumferential narrow grooves.
  7. 7 . The tire according to claim 1 , wherein the width-direction sipe is provided with a widened sipe with a widened width at a groove bottom, and a maximum width and a height from a bottom surface of the widened sipe are 1.2 times or more and 3.0 times or less of a groove width on the surface of the tread portion.
  8. 8 . The tire according to claim 1 , wherein a pair of circumferential main grooves extending in the tire circumferential direction are disposed in the tread portion on an outer side in the tire width direction with the one or more circumferential narrow grooves interposed therebetween, a groove width W 4 of the circumferential main groove with respect to a ground contact width TW of the tread portion is in a range of 3.0% or more and 5.0% or less, and a width TWc in the tire width direction of a land portion defined by the pair of circumferential main grooves and the ground contact width TW are in a range of 0.50≤(TWc/TW)≤0.60.
  9. 9 . The tire according to claim 1 , wherein the one or more circumferential narrow grooves each have a zigzag shape that is repeatedly and alternately bent in the tire width direction while extending in the tire circumferential direction.
  10. 10 . The tire according to claim 9 , wherein the one or more circumferential narrow grooves having the zigzag shape is formed by alternately connecting a long portion and a short portion.
  11. 11 . The tire according to claim 10 , wherein at least one of the notch portions is provided on a convex side of an intersection point of the long portion and the short portion.
  12. 12 . The tire according to claim 10 , wherein one or more of the notch portions are provided in one long portion and bulge toward each of an outer side and an inner side in the tire width direction.
  13. 13 . The tire according to claim 10 , wherein a pitch length P 2 of the one or more circumferential narrow grooves having the zigzag shape and a length L 2 of the long portion in the tire circumferential direction are in a range of 0.85≤(L 2 /P 2 )≤1.00.
  14. 14 . The tire according to claim 1 , wherein the one or more circumferential narrow grooves comprises a plurality of circumferential narrow grooves, a pair of circumferential main grooves extending in the tire circumferential direction are disposed in the tread portion on an outer side in the tire width direction with the plurality of circumferential narrow grooves interposed therebetween, a first land portion defined by the plurality of circumferential narrow grooves is provided between the pair of circumferential main grooves, a second land portion is defined by one circumferential narrow groove of the plurality of circumferential narrow grooves and one main groove of the pair of circumferential main grooves, and a number N 1 of first blocks dividing the first land portion by the width-direction sipe and being aligned in the tire circumferential direction and a number N 2 of second blocks dividing the second land portion by the width-direction sipe and being aligned in the tire circumferential direction are in a range of 1.2≤(N 2 /N 1 )≤2.0.
  15. 15 . The tire according to claim 1 , wherein a ratio of a number of the notch portions bulging toward an inner side to a number of the notch portions bulging toward an outer side in the tire width direction of the one of the one or more circumferential narrow grooves, among the notch portions provided in the at least one of the circumferential narrow grooves, is 0.2 or more and 0.8 or less, along an entire circumference of the tire.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority pursuant to 35 U.S.C. 119(a) to Japanese Patent Application No. 2020-165321, filed Sep. 30, 2020, which application is incorporated herein by reference in its entirety. TECHNICAL FIELD The present technology relates to a tire provided with a circumferential narrow groove having a widened portion with a widened groove width at the groove bottom. BACKGROUND ART In recent years, in order to improve the rolling resistance coefficient (RRC; Rolling Resistance Coefficient), a tire having a tread portion in which a rib-based block pattern is formed by dividing a rib row defined by a plurality of circumferential narrow grooves into lug narrow grooves or sipes and in which block rows are concentrated in a center portion has been sought. In this type of tire, due to the circumferential narrow grooves, the groove volume decreases and wet traction performance is deteriorated. Therefore, a tire has been proposed in which a widened portion having a widened groove width is formed at the groove bottom portion of the circumferential narrow groove to ensure the groove volume to thereby ensure the wet traction performance (for example, see Japan Unexamined Patent Publication No. 2018-529565). However, when the sipes are to be connected to the circumferential narrow groove, in order to maintain the strength of a mold for molding the tire, it is necessary to provide a reinforcing portion in the connection portion between the circumferential narrow groove and the sipe in the mold. Therefore, a duct, which is a space corresponding to the reinforcing portion of the mold, is formed in the connection portion of the circumferential narrow groove with the sipe of the tire so as to extend in the thickness direction of the tread portion. However, in the conventional configuration, due to the duct, problems such as a decrease in the ground contact area of the tread portion and deterioration in the rolling resistance due to a decrease in block rigidity are anticipated, and there is sufficient room for improvement. SUMMARY The present technology provides a tire that can improve wet traction performance and reduce rolling resistance in a compatible manner. A tire according to an embodiment of the present technology is a tire in which a groove width of an opening portion open to a surface of a tread portion is greater than 1.0 mm and 4.0 mm or less, the tire including: one or more circumferential narrow grooves extending in a tire circumferential direction; and a plurality of width-direction sipes communicating with the circumferential narrow grooves, at least one of the circumferential narrow grooves including: a widened portion provided in a region in which a groove depth from the surface of the tread portion is 30% or more of a maximum groove depth and having a groove width wider than the opening portion; and a plurality of notch portions provided at intervals in the tire circumferential direction to bulge toward one side in a tire width direction to communicate from the surface of the tread portion to the widened portion, and the width-direction sipe being connected to at least one of the notch portions. In the tire, preferably, an opening area of the notch portion in the surface of the tread portion is 1.5 mm2 or more and 10.0 mm2 or less. In the tire, preferably, a width Wa of the notch portion and a groove width W1 of the opening portion are in a range of 0.5≤(Wa/W1)≤2.0. In the tire, preferably, the number of the notch portions provided in one circumferential narrow groove is 10 or more and 20 or less in a ground contact surface of the tread portion. In the tire, preferably, a ratio of the number of the notch portions bulging toward an inner side to the number of the notch portions bulging toward an outer side in the tire width direction of the circumferential narrow groove, among the notch portions provided in one circumferential narrow groove, is 0.2 or more and 1.0 or less. In the tire, preferably, a maximum groove width W2 of the widened portion and a groove width W1 of the opening portion are in a range of 1.0<(W2/W1)≤4.0, and a width Wb from the opening portion to the widened portion and a width Wa of the notch portion are in a range of 0.5≤(Wa/Wb)≤2.0. In the tire, preferably, a groove depth H4 of the width-direction sipe satisfies a relationship of H3<H4<0.9 H1, with respect to: a depth H3 from the surface of the tread portion in the circumferential narrow groove to a connection portion between the notch portion and the widened portion; and a maximum groove depth H1 of the circumferential narrow groove. In the tire, preferably, the width-direction sipe is provided with a widened sipe with a widened width at a groove bottom, and a maximum width and a height from a bottom surface of the widened sipe are 1.2 times or more and 3.0 times or less of a groove width on the surface of the tread portion. In the tire, preferably, a pair of circumferential main groo