JP2018020689A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve on-snow steering performance while improving abrasion resistance performance in a shoulder rib.SOLUTION: In a shoulder rib 23B are provided: a plurality of lug grooves 11 which extend in a tire width direction, terminate in the shoulder rib without communicating with a shoulder main groove 22B and are provided in a tire circumferential direction; sipes 12 which extend in the tire width direction, terminate in the shoulder rib without communicating with the main groove and are provided in the tire circumferential direction to be alternate with the lug grooves; a circumferential narrow groove 13, both end parts of which communicate with and terminate in end parts at which a pair of lug grooves which extend in the tire circumferential direction and are adjacent to each other in the tire circumferential direction and main grooves of sipes terminate; and chamfers 12A formed, in an extending direction of the sipes, at opening edges of the sipes. A plurality of combinations of the pair of lug grooves, the sipes and the circumferential narrow grooves are provided parallely in the tire circumferential direction, and groove widths Wa of the lug grooves, groove widths Wb' of the sipes exclusive of the chamfers and groove widths Wc of the circumferential narrow grooves satisfy a relation of: Wa>Wb' and Wc>Wb'.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pneumatic tire.

  Conventionally, for example, the pneumatic tire described in Patent Document 1 is intended to have excellent drainage performance while maintaining on-snow performance and on-ice performance. In this pneumatic tire, a land portion is defined by a plurality of main grooves extending continuously in the tire circumferential direction on a tread surface, and at least one land portion is formed of one of main grooves on both sides whose one end defines a land portion. A horizontal groove that opens in one main groove and extends in the tire width direction, the other end terminates in the land portion, and one end that opens in one main groove and extends in the tire width direction, and the other end terminates in the land portion. And a circumferential sipe extending in the tire circumferential direction and having both ends terminated in the land portion, the other end of the width sipe is connected to one end of the circumferential sipe, and the other end of the lateral groove is It connects with a circumferential sipe, and the other end of the circumferential sipe terminates at a position extending in the tire circumferential direction beyond the connection position with the lateral groove.

  Further, for example, the pneumatic tire described in Patent Document 2 is intended to exhibit excellent steering stability performance while ensuring uneven wear performance and drainage performance. This pneumatic tire is provided with a plurality of land portions partitioned by a plurality of main grooves extending along the tire circumferential direction on the tread surface, and at least one of the land portions located on the outermost side in the tire width direction is It consists of shoulder ribs that extend continuously in the tire circumferential direction. The shoulder ribs have narrow grooves that extend along the tire circumferential direction and close both ends, and from both ends of the narrow grooves outward in the tire width direction. A plurality of extending sipe shapes are formed at intervals in the tire circumferential direction.

JP 2015-168302 A JP2012-140049A

  The pneumatic tire described in Patent Document 1 has drainage performance due to a lateral groove, a width-direction sipe, and a circumferential sipe, but ends at a position where the circumferential sipe extends further in the tire circumferential direction beyond the connection position with the lateral groove. And the fact that one end of the lateral groove and the widthwise sipe is open to the main groove may reduce the rigidity of the land portion and impair wear resistance.

  In the pneumatic tire described in Patent Document 2, both ends of a narrow groove extending along the tire circumferential direction are closed in the shoulder rib, and a cut-out sipe extending from the both ends of the narrow groove to the outside in the tire width direction is provided. By adopting a structure that does not communicate with the main groove, uneven wear resistance performance is ensured, but since the groove communicating with the circumferential narrow groove is a sipe, the drainage cannot be improved and the turning performance on snow can be improved. Is difficult.

  The present invention has been made in view of the above, and it is possible to improve the turning performance on snow by ensuring the edge component and the drainage performance while suppressing the rigidity reduction in the shoulder rib and improving the wear resistance performance. An object is to provide a pneumatic tire.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to one aspect of the present invention includes a main groove extending in the tire circumferential direction and arranged in a plurality in the tire width direction in the tread portion, A plurality of land portions defined by main grooves and extending along the tire circumferential direction, and a tire width in the tire width direction outer shoulder rib of the outermost main groove in the tire width direction. A plurality of lug grooves provided in the tire circumferential direction that terminate in the shoulder rib without communicating with the main groove on the outermost side in the tire width direction, and extend along the tire width direction. A sipe that terminates in the shoulder rib without communicating with the outermost main groove in the tire width direction and is provided alternately with the lug groove in the tire circumferential direction, and extends along the tire circumferential direction and extends in the tire circumferential direction A pair of lug grooves adjacent to each other And a circumferential narrow groove whose both ends communicate with and terminate at each end of the sipe on the main groove side, and a chamfer formed at the opening edge of the sipe along the extending direction of the sipe. A plurality of combinations formed by the pair of the lug grooves and the sipes and the circumferential narrow grooves are provided side by side in the tire circumferential direction, and the groove width Wa of the lug grooves and the chamfering are provided. The groove width Wb ′ of the sipe excluding the groove width Wc of the circumferential narrow groove has a relationship of Wa> Wb ′ and Wc> Wb ′.

  According to this pneumatic tire, by having the circumferential narrow groove, the shoulder rib compensates for the edge component in the direction intersecting the tire circumferential direction, and the turning performance on snow (snow traction performance) at the time of chain mounting is achieved. Can be increased. Moreover, each end of the circumferential narrow groove communicates and terminates at the lug groove adjacent to the tire circumferential direction and the end of the sipe, thereby ensuring the rigidity of the shoulder rib and improving the wear resistance performance, and the circumferential direction. The edge effect can be increased at the corners formed by each end of the narrow groove and the end of the lug groove or sipe. In addition, due to the chamfering provided in the sipe, drainage on the snow can be secured without reducing the rigidity of the shoulder rib as much as possible. Moreover, the groove width Wa of the lug groove, the groove width Wb ′ of the sipe excluding chamfering, and the groove width Wc of the circumferential narrow groove have a relationship of Wa> Wb ′ and Wc> Wb ′. It is possible to ensure both the rigidity of the shoulder rib and the drainage. As a result, the turning performance on snow can be improved while improving the wear resistance performance of the shoulder rib.

  In the pneumatic tire according to one aspect of the present invention, the groove width Wa of the lug groove, the groove width Wb of the sipe including the chamfer, and the groove width Wc of the circumferential narrow groove are Wa> Wc ≧ The relationship between Wb, the groove width Wa of the lug groove, the groove width Wb ′ of the sipe excluding the chamfer, and the groove width Wc of the circumferential narrow groove are expressed as Wa> Wc> Wb ′. Preferably there is.

  According to this pneumatic tire, the drain width can be improved by including the groove width Wc of the circumferential narrow groove and the groove width Wb of the sipe including chamfering as Wc ≧ Wb. By setting the groove width Wc and the groove width Wb ′ of the sipe excluding chamfering to be Wc> Wb ′, the rigidity of the shoulder rib can be ensured. Moreover, drainage can be improved by making the groove width Wa of the lug groove larger than the groove width Wc of the circumferential narrow groove and the groove widths Wb and Wb 'of the sipe. Further, the circumferential narrow groove is clogged on snow if the groove width Wc is not secured to some extent, and the edge effect is reduced. If the groove is too thick, the rigidity of the shoulder rib is reduced. Therefore, the relationship of Wa> Wc> Wb ′. By doing, it is possible to achieve both the edge effect and the effect of ensuring the rigidity of the shoulder rib.

  In the pneumatic tire according to one aspect of the present invention, the groove depth Da of the lug groove, the groove depth Db of the sipe, and the groove depth Dc of the circumferential narrow groove are Da> Dc, and Db It is preferable that the relationship is> Dc.

  According to this pneumatic tire, when the circumferential narrow groove communicates with the lug groove and the sipe, the rigidity of the shoulder rib tends to decrease. However, the circumferential depth of the groove Dc is set to the groove depth Da of the lug groove and By making it shallower than the sipe groove depth Db, the rigidity of the shoulder rib can be ensured.

  In the pneumatic tire according to one aspect of the present invention, in the shoulder rib, the lug groove adjacent to the tire circumferential direction between the pair of the lug groove and the combination formed by the sipe and the circumferential narrow groove. In the tire width direction inner side region in which the sipe is extended inward in the tire width direction and the circumferential narrow groove is extended in the tire circumferential direction, one end communicates with the main groove on the outermost side in the tire width direction, and the other end It is preferable to provide an auxiliary sipe provided at the end.

  According to this pneumatic tire, an auxiliary sipe is provided to reduce excessive local rigidity in the region near the shoulder main groove between the pair of lug grooves and the combination of the sipe and the circumferential narrow groove. In addition, the ground contact characteristics of the entire shoulder rib can be improved. Moreover, by providing the auxiliary sipe, the edge component in the entire shoulder rib can be adjusted.

  In the pneumatic tire according to one aspect of the present invention, the auxiliary sipe reaches the other end terminated from one end communicating with the main groove on the outermost side in the tire width direction toward the outer end in the tire width direction of the lug groove. It is preferable that it extends and is inclined with respect to the tire circumferential direction, and the angle with respect to the tire circumferential direction on the lug groove side is in a range of 30 degrees or more and 70 degrees or less.

  According to this pneumatic tire, by providing the auxiliary sipe so as to be inclined with respect to the tire circumferential direction, edge components in the tire circumferential direction and the tire width direction can be obtained, which can contribute to the improvement in characteristics in running on snow. .

  The pneumatic tire according to the present invention can improve the turning performance on snow by ensuring the edge component and the drainage performance while suppressing the decrease in rigidity in the shoulder rib and improving the wear resistance performance.

FIG. 1 is a meridional sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view of the pneumatic tire according to the embodiment of the present invention. FIG. 3 is an enlarged plan view of the pneumatic tire according to the embodiment of the present invention. FIG. 4 is a cross-sectional view taken along the line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG. FIG. 6 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. Further, a plurality of modifications described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

  The pneumatic tire according to this embodiment will be described. FIG. 1 is a meridional sectional view of a pneumatic tire according to this embodiment. FIG. 2 is a plan view of the pneumatic tire according to the present embodiment. FIG. 3 is an enlarged plan view of the pneumatic tire according to the present embodiment. FIG. 4 is a cross-sectional view taken along the line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL. In the present embodiment, the same sign “CL” as that of the tire equator plane is attached to the tire equator line.

  As shown in FIG. 1, the pneumatic tire 1 according to the present embodiment includes a tread portion 2, shoulder portions 3 on both sides thereof, and a sidewall portion 4 and a bead portion 5 that are sequentially continuous from the shoulder portions 3. ing. The pneumatic tire 1 includes a carcass layer 6 and a belt layer 7.

  The tread portion 2 is made of a rubber material (tread rubber), is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that contacts the road surface during traveling. The tread surface 21 extends along the tire circumferential direction, and a plurality of main grooves 22 (three in this embodiment) are provided in the tire width direction. The tread surface 21 extends along the tire circumferential direction by the plurality of main grooves 22, and a plurality of rib-like land portions 23 (four in this embodiment) parallel to the tire equator line CL are formed. .

  In the present embodiment, the outermost main groove 22 in the tire width direction is referred to as a shoulder main groove 22B, and the main grooves 22 other than the shoulder main groove 22B are referred to as inner main grooves 22A. Further, the rib-shaped land portion 23 on the outer side in the tire width direction of the shoulder main groove 22B is referred to as a shoulder rib 23B, and the rib-shaped land portion 23 sandwiched between the inner main groove 22A and the shoulder main groove 22B is referred to as an inner rib 23A. The main groove 22 has a groove width of 3 mm to 20 mm and a groove depth of 5 mm to 10 mm.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. Further, the sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire 1. The bead unit 5 includes a bead core 51 and a bead filler 52. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 52 is a rubber material disposed in a space formed by folding the end portion in the tire width direction of the carcass layer 6 at the position of the bead core 51.

  The carcass layer 6 is configured such that each tire width direction end portion is folded back from the tire width direction inner side to the tire width direction outer side by a pair of bead cores 51 and is wound around in a toroidal shape in the tire circumferential direction. It is. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged in parallel at an angle in the tire circumferential direction with an angle with respect to the tire circumferential direction being along the tire meridian direction. The carcass cord is made of organic fibers (polyester, rayon, nylon, etc.). The carcass layer 6 is provided as at least one layer.

  The belt layer 7 has a multilayer structure in which at least two belts 7A and 7B are laminated, and is disposed on the tire radial direction outer side of the carcass layer 6 in the tread portion 2 and covers the carcass layer 6 in the tire circumferential direction. It is. The belts 7A and 7B are made by coating a plurality of cords (not shown) arranged in parallel at a predetermined angle (for example, 20 degrees to 30 degrees) with a coat rubber with respect to the tire circumferential direction. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). Further, the overlapping belts 7A and 7B are arranged so that the cords intersect each other.

  Although not clearly shown in the drawing, a belt reinforcing layer may be provided on the outer side of the belt layer 7 in the tire radial direction. The belt reinforcing layer covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer is coated with a coat rubber on a plurality of cords (not shown) arranged substantially parallel to the tire circumferential direction (± 5 degrees) in the tire width direction. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). The belt reinforcing layer is provided by winding a strip-shaped strip material (for example, a width of 10 [mm]) in the tire circumferential direction. The belt reinforcing layer is, for example, disposed so as to cover only the end portion in the tire width direction of the belt layer 7, or disposed so as to cover the entire belt layer 7, or has two layers of reinforcing layers. The reinforcing layer on the inner side in the radial direction is formed so as to be larger in the tire width direction than the belt layer 7 and covers the entire belt layer 7, and the reinforcing layer on the outer side in the tire radial direction covers only the end in the tire width direction of the belt layer 7. Or two reinforcing layers, and each reinforcing layer is arranged so as to cover only the end portion of the belt layer 7 in the tire width direction.

  In such a configuration, the pneumatic tire 1 of the present embodiment is provided with the lug groove 11, the sipe 12, the circumferential narrow groove 13, and the auxiliary sipe 14 on the tread surface 21 of the shoulder rib 23B. Yes. There are no other grooves in the shoulder rib 23B.

  The lug grooves 11 are provided extending along the tire width direction so as to intersect the tire circumferential direction. The lug grooves 11 do not communicate with the outermost shoulder main groove 22B in the tire width direction, terminate in the shoulder rib 23B, and are provided in a plurality in the tire circumferential direction. In the lug groove 11, a chamfer 11 </ b> A is formed along an extending direction of the lug groove 11 at an opening edge that opens to the tread surface 21 (the surface of the shoulder rib 23 </ b> B). In the present embodiment, the chamfer 11A is provided on one opening edge of the lug groove 11 (the sipe 12 side (inside) in the shoulder groove unit 10 described below), but the chamfer 11A may be provided on the other opening edge. Good. Further, the chamfer 11A may be omitted. When the lug groove 11 has the chamfer 11A, the groove width Wa including the chamfer 11A is in the range of 2.0 mm to 6.5 mm, and the groove width Wa ′ not including the chamfer 11A is 1.5 mm. It is narrower than the main groove 22 in the range of 5.5 mm or less. Usually, the groove width of the lug groove 11 is the groove width Wa including the chamfer 11A. Further, the lug groove 11 is formed shallower than the main groove 22 in the range where the groove depth Da is 4.0 mm or more and 9.0 mm or less. In addition, when the lug groove 11 has the chamfer 11A, the depth of the chamfer 11A from the tread surface 21 is 40% or less of the effective groove depth. Although the effective groove depth is not clearly shown in the drawing, the main groove 22 has a bottom upper portion called a wear indicator indicating a wear limit on the groove bottom, and the main groove 22 from the tread surface 21 to the upper surface of the wear indicator. The depth of the groove. Further, the angle of the chamfer 11A with respect to the tire radial direction is preferably in the range of 20 degrees to 70 degrees.

  The lug groove 11 is provided so as to intersect with the ground contact end T. The ground contact end T refers to both outermost ends in the tire width direction of the ground contact region, and in FIG. 2, the ground contact end T is shown continuously in the tire circumferential direction. The ground contact area is a flat surface in which the tread surface 21 of the tread portion 2 of the pneumatic tire 1 is dried when the pneumatic tire 1 is assembled on a regular rim and filled with a regular internal pressure and 70% of the regular load is applied. This is an area where it touches the ground. The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load is “maximum load capacity” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

  Moreover, the lug groove 11 is formed linearly along the tire width direction. The lug grooves 11 are provided with an inclination angle α in a range of 2 degrees to 15 degrees with respect to the tire width direction. The inclination angle α is an angle formed by the center line L1 passing through the center of the groove width Wa not including the chamfer 11A of the lug groove 11 and the base line L2 in the tire width direction. Note that the lug groove 11 may be formed to be curved in the extending direction, though not explicitly shown in the drawing. In this case, the inclination angle α is an angle formed by the center line passing through the center of the groove width Wa not including the chamfer 11A of the lug groove 11 and the base line in the tire width direction at each end of the lug groove 11.

  The sipe 12 is provided extending along the tire width direction so as to intersect the tire circumferential direction. The sipe 12 does not communicate with the outermost shoulder main groove 22B in the tire width direction, terminates in the shoulder rib 23B, is provided in the tire circumferential direction, and is provided alternately in the lug grooves 11 and the tire circumferential direction. In the sipe 12, a chamfer 12 </ b> A is formed along the extending direction of the sipe 12 at the opening edge that opens to the tread surface 21 (the surface of the shoulder rib 23 </ b> B). In the present embodiment, the chamfer 12A is provided on one opening edge of the sipe 12 (on the opposite side (outside) of the lug groove 11 in the shoulder groove unit 10 described below), but is provided on the other opening edge. May be. In the sipe 12, the groove width Wb including the chamfer 12A is in the range of 1.0 mm to 3.0 mm, and the groove width Wb ′ not including the chamfer 12A is in the range of 0.5 mm to 1.5 mm. It is formed narrower than the lug groove 11. The sipe 12 is formed shallower than the main groove 22 in a range where the groove depth Db is 4.0 mm or more and 9.0 mm or less. The sipe 12 is provided so as to intersect the grounding end T. Further, the length of the sipe 12 in the extending direction is aligned with the lug groove 11 in the tire circumferential direction on the shoulder main groove 22B side which is the inner side in the tire width direction, but is longer than the lug groove 11 on the outer side in the tire width direction. Is also formed short. The sipe 12 is provided in parallel with the lug groove 11. The depth of the chamfer 12A from the tread surface 21 is 40% or less of the effective groove depth. The angle of the chamfer 12A with respect to the tire radial direction is preferably in the range of 20 degrees to 70 degrees.

  The circumferential narrow groove 13 is provided to extend linearly along the tire circumferential direction. The circumferential narrow groove 13 is terminated with both ends thereof communicating with a pair of lug grooves 11 adjacent to each other in the tire circumferential direction and the end portions of the sipe 12 on the shoulder main groove 22B side that are on the inner side in the tire width direction. Is provided. And the circumferential direction fine groove 13 is formed more than the groove width Wb including the chamfer 12A of the sipe 12 in the range where the groove width Wc is 1.5 mm or more and 3.5 mm or less. Further, the circumferential narrow groove 13 is formed so that the groove width Wc is wider than the groove width Wb ′ not including the chamfer 12 </ b> A of the sipe 12. Further, the circumferential narrow groove 13 is formed shallower than the lug groove 11 and the sipe 12 in the range where the groove depth Dc is 1.0 mm or more and 7.0 mm or less.

  Thus, the pair of lug grooves 11 and sipes 12 adjacent to each other in the tire circumferential direction and the circumferential narrow groove 13 are formed by continuously combining in a U shape, and the open side of the U shape is in the tire width direction. It is arranged toward the outside. A pair of lug grooves 11 and sipes 12 adjacent to each other in the tire circumferential direction and a circumferential groove 13 are continuously formed into a U-shaped combination as a shoulder groove unit 10, and the shoulder groove unit 10 is a tire circumferential direction. Are provided side by side.

  The auxiliary sipe 14 extends, in the shoulder rib 23B, the lug groove 11 and the sipe 12 adjacent in the tire circumferential direction between the shoulder groove units 10 in the tire width direction, and the circumferential narrow groove 13 in the tire circumferential direction. Is provided in a region G on the inner side in the tire width direction. The region G includes the center line L1 of the lug groove 11 described above, the center line L3 passing through the center of the groove width Wc not including the chamfer 12A in the sipe 12, and the edge on the inner side in the tire width direction of the circumferential narrow groove 13. Is a region surrounded by the straight line L4 passing through the outer edge of the shoulder main groove 22B in the tire width direction. In this region G, the auxiliary sipe 14 is provided with one end communicating with the shoulder main groove 22B and the other end terminating. The auxiliary sipe 14 has a groove width in a range of 0.5 mm or more and 1.2 mm or less, and is formed shallower than the lug groove 11 in a range of a groove depth of 2.0 mm or more and 7.0 mm or less.

  The auxiliary sipe 14 extends from the one end of the shoulder main groove 22B to the other end and extends toward the outer end of the lug groove 11 in the tire width direction. The distance between the other end of the auxiliary sipe 14 and the lug groove 11 is 5 mm or less. Further, the auxiliary sipe 14 is provided so as to be inclined with respect to the tire circumferential direction, and an angle β with respect to the tire circumferential direction on the lug groove 11 side is provided in a range of 30 degrees to 70 degrees. The auxiliary sipe 14 is formed such that its extending direction intersects with the extending direction of the lug groove 11 (center line L1). That is, the auxiliary sipe 14 and the lug groove 11 are arranged in a dogleg shape so as to bend each other.

  The pneumatic tire 1 of the present embodiment extends in the tire width direction outermost shoulder rib 23B along the tire width direction and does not communicate with the tire width direction outermost shoulder main groove 22B. A plurality of lug grooves 11 that terminate in the tire circumferential direction and terminate in the shoulder rib 23B without communicating with the outermost shoulder main groove 22B extending in the tire width direction and extending in the tire width direction. Sipe 12 provided alternately with lug grooves 11 in the direction, a pair of lug grooves 11 extending along the tire circumferential direction and adjacent to each other in the tire circumferential direction, and each end terminated on the shoulder main groove 22B side of sipe 12 And a chamfer 12A formed at the opening edge of the sipe 12 along the extending direction of the sipe 12, and a pair of lug grooves 11 and Sipe 2 and a plurality of shoulder groove units 10 formed in the circumferential direction narrow groove 13 are provided side by side in the tire circumferential direction, the groove width Wa of the lug groove 11, and the groove width Wb ′ of the sipe 12 excluding the chamfer 12A, The groove width Wc of the circumferential narrow groove 13 is such that Wa> Wb ′ and Wc> Wb ′.

  According to the pneumatic tire 1, by having the circumferential narrow groove 13, the shoulder rib 23B compensates for the edge component in the direction intersecting the tire circumferential direction, and the turning performance on snow (snow traction) when the chain is mounted. Performance). Moreover, the end portions of the circumferential narrow grooves 13 communicate with and terminate at the ends of the lug grooves 11 and sipes 12 adjacent to each other in the tire circumferential direction, thereby ensuring the rigidity of the shoulder rib 23B and improving the wear resistance. In addition, the edge effect can be increased at the corner portion formed by each end portion of the circumferential narrow groove 13 and the end of the lug groove 11 or the sipe 12. In addition, the chamfer 12A provided on the sipe 12 can ensure drainage on snow without reducing the rigidity of the shoulder rib 23B as much as possible. Moreover, the groove width Wa of the lug groove 11, the groove width Wb ′ of the sipe 12 excluding the chamfer 12 </ b> A, and the groove width Wc of the circumferential narrow groove 13 are expressed by the relationship of Wa> Wb ′ and Wc> Wb ′. By doing so, it is possible to achieve both the rigidity of the shoulder rib 23B and the drainage. As a result, the turning performance on snow can be improved while improving the wear resistance performance in the shoulder rib 23B.

  Further, in the pneumatic tire 1 of the present embodiment, the groove width Wa of the lug groove 11, the groove width Wb of the sipe 12 including the chamfer 12A, and the groove width Wc of the circumferential narrow groove 13 are Wa> Wc ≧ The relationship between Wb, the groove width Wa of the lug groove 11, the groove width Wb ′ of the sipe 12 excluding the chamfer 12A, and the groove width Wc of the circumferential narrow groove 13 is a relationship of Wa> Wc> Wb ′. Preferably there is. That is, since the depth from the tread surface 21 of the chamfer 12A of the sipe 12 is 40% or less of the effective groove depth, the groove width Wb ′ of the sipe 12 excluding the chamfer 12A is 40% of the effective groove depth. The groove width at the position exceeding the groove width is narrower than the groove width Wa of the lug groove 11 and the groove width Wc of the circumferential narrow groove 13.

  According to this pneumatic tire 1, the drainage performance can be improved by including the equivalent of Wc ≧ Wb as the groove width Wc of the circumferential narrow groove 13 and the groove width Wb of the sipe 12 including the chamfer 12A. By setting the groove width Wc of the directional narrow groove 13 and the groove width Wb ′ of the sipe 12 excluding the chamfer 12A to satisfy Wc> Wb ′, the rigidity of the shoulder rib 23B can be ensured. Moreover, drainage can be improved by making the groove width Wa of the lug groove 11 larger than the groove width Wc of the circumferential narrow groove 13 and the groove widths Wb and Wb ′ of the sipe 12. Further, if the groove width Wc is not secured to some extent, the circumferential narrow groove 13 is clogged on the snow and the edge effect is lowered. If it is too thick, the rigidity of the shoulder rib 23B is lowered, so that Wa> Wc> Wb ′. With this relationship, both the edge effect and the effect of ensuring the rigidity of the shoulder rib 23B can be achieved.

  Further, in the pneumatic tire 1 of the present embodiment, the groove depth Da of the lug groove 11, the groove depth Db of the sipe 12, and the groove depth Dc of the circumferential narrow groove 13 are Da> Dc and Db. It is preferable that the relationship is> Dc.

  According to the pneumatic tire 1, when the circumferential narrow groove 13 communicates with the lug groove 11 and the sipe 12, the rigidity of the shoulder rib 23 </ b> B tends to be reduced. The rigidity of the shoulder rib 23B can be ensured by making it shallower than the groove depth Da of 11 and the groove depth Db of the sipe 12. Note that the groove depth Dc of the circumferential narrow groove 13 is preferably 70% or less of the above-described effective groove depth in order to ensure the rigidity of the shoulder rib 23B.

  Further, in the pneumatic tire 1 of the present embodiment, the lug grooves adjacent to each other in the tire circumferential direction between the pair of lug grooves 11 and the shoulder groove unit 10 formed by the sipe 12 and the circumferential narrow groove 13 in the shoulder rib 23B. 11 and the sipe 12 extend inward in the tire width direction, and in the tire width direction inner side region G in which the circumferential narrow groove 13 extends in the tire circumferential direction, one end communicates with the shoulder main groove 22B and the other end terminates. It is preferable to provide the auxiliary sipe 14 provided.

  According to this pneumatic tire 1, by providing the auxiliary sipe 14, the region close to the shoulder main groove 22 </ b> B between the pair of lug grooves 11 and the shoulder groove unit 10 formed by the sipe 12 and the circumferential narrow groove 13. Excessive local rigidity in G can be alleviated, and the ground contact characteristics of the entire shoulder rib 23B can be improved. Moreover, by providing the auxiliary sipe 14, the edge component in the entire shoulder rib 23B can be adjusted. In addition, when the space | interval of the other end of the auxiliary sipe 14 and the lug groove 11 shall be 5 mm or less, it is preferable when relieving the excess of local rigidity.

  Further, in the pneumatic tire 1 of the present embodiment, the auxiliary sipe 14 extends from the one end communicating with the shoulder main groove 22B to the other end terminated toward the outer end in the tire width direction of the lug groove 11, and It is preferable that the angle with respect to the tire circumferential direction is provided and the angle with respect to the tire circumferential direction on the lug groove 11 side is in a range of 30 degrees or more and 70 degrees or less.

  According to the pneumatic tire 1, by providing the auxiliary sipe 14 in an inclined manner with respect to the tire circumferential direction, edge components in the tire circumferential direction and the tire width direction can be obtained, which contributes to improvement in characteristics in running on snow. Can do. The auxiliary sipe 14 is provided so as to be inclined with respect to the extending direction of the lug groove 11, so that the extending directions are different from each other, and the edge effect can be further improved.

  By the way, as shown in FIGS. 2 and 3, the pneumatic tire 1 of the present embodiment is provided on the inner side in the tire width direction of the shoulder main groove 22B and is adjacent to the shoulder rib 23B across the shoulder main groove 22B. In 23A, an inner groove unit 30 is provided. The inner groove unit 30 includes a lug groove 31, a first sipe 32, and a second sipe 33. A plurality of inner groove units 30 are arranged in the tire circumferential direction. The inner rib 23 </ b> A has no groove other than the inner groove unit 30.

  The lug groove 31 is formed in a straight line along the tire width direction, and one end communicates with the shoulder main groove 22B and the other end terminates in the inner rib 23A. The lug groove 31 is disposed to face the auxiliary sipe 14 with the shoulder main groove 22B interposed therebetween, and is provided on an extension line L5 in which the auxiliary sipe 14 extends. That is, the lug groove 31 is inclined at the same angle β as the auxiliary sipe 14. The lug groove 31 has a groove width in the range of 1.5 mm to 4.0 mm, and is shallower than the main groove 22 in a groove depth of 2 mm to 9 mm.

  The first sipe 32 is formed in a straight line, and both ends are provided to terminate in the inner rib 23 </ b> A, and one end is provided toward the other end where the lug groove 31 is terminated. The 1st sipe 32 is provided in 90 degrees or more and 150 degrees or less with respect to the extension line L5 in which the lug groove 31 is arrange | positioned. The first sipe 32 has a groove width in a range of 0.4 mm or more and 1.5 mm or less, and is shallower than the main groove 22 in a range of a groove depth of 2 mm or more and 9 mm or less.

  The second sipe 33 is formed in a straight line, one end is terminated in the inner rib 23 </ b> A, the other end is provided in communication with the inner main groove 22 </ b> A, and one end is disposed at the other end where the lug groove 31 is terminated. It is provided for. The second sipe 33 is provided in a range of 90 degrees or more and 150 degrees or less with respect to the extension line L5 where the lug groove 31 is disposed. The second sipe 33 has a groove width in the range of 0.4 mm to 1.5 mm, and is shallower than the main groove 22 in a range of the groove depth of 2 mm to 9 mm.

  The inner groove unit 30 provided in this way is disposed so that the three grooves of the lug groove 31, the first sipe 32, and the second sipe 33 face each other without crossing each other. Since the rigidity of the inner rib 23A is ensured while maintaining the properties, wear resistance can be ensured. And since each groove | channel is arrange | positioned in 90 degrees or more and 150 degrees or less, the rigidity of inner side rib 23A can be ensured uniformly.

  In the present embodiment, the inner main groove 22A is disposed on the tire equator plane CL, and the land portions 23 and the grooves on both sides in the tire width direction are disposed symmetrically between the tire equator plane CL.

  Further, in the above-described embodiment, three main grooves 22 are provided, and the central inner main groove 22A is disposed on the tire equatorial plane CL, and the inner ribs 23A and the shoulder ribs are respectively formed on the tire equatorial plane CL on the outer side in the tire width direction. 23B is formed. The number of the main grooves 22 is not limited to this configuration, and at least two main grooves are provided, and the shoulder ribs 23B on the outer side in the tire width direction of the main grooves on the outermost side in the tire width direction are used in the present embodiment. The shoulder groove unit 10 may be provided, or the auxiliary sipes 14 may be further provided.

  In this example, performance tests regarding snow turning performance and wear resistance performance were performed on a plurality of types of pneumatic tires having different conditions (see FIG. 6).

  In this performance test, the pneumatic tire (test tire) shown in FIG. 6 having a tire size of 185 / 65R15 and a main groove depth of 7 mm is assembled on a regular rim of 15 × 6 J, and a regular internal pressure of 180 kPa is applied. It was filled and mounted on a test vehicle (front drive vehicle with a displacement of 1.5 L).

  The method for evaluating snow turning ability is run on a snow test course assuming a city area with the above test vehicle with a chain attached to the drive wheels, and a 10-step evaluation is performed by a test driver. This evaluation indicates that the higher the score, the better the turning performance on snow.

  The evaluation method of the wear resistance performance was to confirm the amount of wear on the shoulder rib of the front tire after traveling 12,000 km on a test course on a dry road surface with the above test vehicle. And it shows by the index | exponent which used the pneumatic tire of the prior art example as the reference | standard (100), and has shown that abrasion resistance performance is excellent, so that an index | exponent is large.

  In FIG. 6, the groove structure in the shoulder rib of the pneumatic tire of the conventional example, the comparative example 1, and Examples 1-Example 6 is as a block diagram. And as shown to the test result of FIG. 6, it turns out that the pneumatic tire of Example 1- Example 8 has improved on-snow turning performance and abrasion resistance performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 21 Tread surface 22 Main groove 22A Inner main groove 22B Shoulder main groove 23 Land part 23A Inner rib 23B Shoulder rib 10 Shoulder groove unit 11 Lug groove 11A Chamfer 12 Sipe 12A Chamfer 13 Circumferential narrow groove 14 Auxiliary sipes

Claims (5)

The tread portion is provided with a main groove extending along the tire circumferential direction and arranged in the tire width direction, and a plurality of land portions defined by the main groove and extending along the tire circumferential direction. In the tire,
To the shoulder rib on the outer side in the tire width direction of the main groove on the outermost side in the tire width direction,
Lug grooves that extend along the tire width direction and terminate in the shoulder rib without communicating with the main groove on the outermost side in the tire width direction, and are provided in a plurality in the tire circumferential direction;
Sipes extending along the tire width direction and terminating in the shoulder ribs without communicating with the outermost main groove in the tire width direction and alternately provided with the lug grooves in the tire circumferential direction;
A pair of lug grooves extending along the tire circumferential direction and adjacent to each other in the tire circumferential direction, and circumferential narrow grooves whose both ends communicate with each other and terminate on the main groove side of the sipe;
A chamfer formed at the opening edge of the sipe along the extending direction of the sipe;
A plurality of combinations formed by the pair of lug grooves and the sipes and the circumferential narrow grooves are provided side by side in the tire circumferential direction,
Air in which the groove width Wa of the lug groove, the groove width Wb ′ of the sipe excluding the chamfer, and the groove width Wc of the circumferential narrow groove have a relationship of Wa> Wb ′ and Wc> Wb ′. Enter tire.   The groove width Wa of the lug groove, the groove width Wb of the sipe including the chamfer, and the groove width Wc of the circumferential narrow groove have a relationship of Wa> Wc ≧ Wb, and the groove width of the lug groove 2. The pneumatic tire according to claim 1, wherein Wa, a groove width Wb ′ of the sipe excluding the chamfer, and a groove width Wc of the circumferential narrow groove have a relationship of Wa> Wc> Wb ′.   The groove depth Da of the lug groove, the groove depth Db of the sipe, and the groove depth Dc of the circumferential narrow groove have a relationship of Da> Dc and Db> Dc. The described pneumatic tire.   In the shoulder rib, the lug groove and the sipe adjacent to each other in the tire circumferential direction are extended inward in the tire width direction between the combination of the pair of lug grooves and the sipe and the circumferential narrow groove, And in the tire width direction inside area | region which extended the said circumferential direction narrow groove in the tire circumferential direction, it has an auxiliary sipe provided with one end communicating with the main groove on the outermost side in the tire width direction and terminating the other end. Item 4. The pneumatic tire according to any one of Items 1 to 3.   The auxiliary sipe extends from one end communicating with the outermost main groove at the outermost side in the tire width direction to the other end terminated toward the outer end in the tire width direction of the lug groove and is inclined with respect to the tire circumferential direction The pneumatic tire according to claim 4, wherein an angle of the lug groove side with respect to the tire circumferential direction is in a range of 30 degrees to 70 degrees.

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