Pneumatic tire
阅读说明:本技术 充气轮胎 (Pneumatic tire ) 是由 远藤丰明 于 2019-03-26 设计创作,主要内容包括:充气轮胎的胎面花纹具备一对周向主槽、由所述一对周向主槽在轮胎宽度方向上划分出的陆部、以及设置于所述陆部的区域内并将所述一对周向主槽之间连接且在轮胎周向上隔开间隔地设置有多个的刀槽花纹。所述刀槽花纹各自具有向轮胎周向的第1侧突出的山形状。在沿着轮胎宽度方向的所述胎面部的轮廓截面中,在将通过所述陆部的胎面表面与所述一对周向主槽的槽壁面分别连接的2个陆部边缘的点、且中心点位于所述轮胎赤道线上的圆弧设为基准轮廓线时,由所述陆部的胎面表面形成的轮廓线是比所述基准轮廓线向轮胎径向外侧突出的鼓出轮廓线。(A tread pattern of a pneumatic tire includes a pair of circumferential main grooves, a land portion defined by the pair of circumferential main grooves in a tire width direction, and a plurality of sipes provided in a region of the land portion, connecting the pair of circumferential main grooves, and provided at intervals in a tire circumferential direction. The sipes each have a mountain shape protruding toward the 1 st side in the tire circumferential direction. In a profile cross section of the tread portion in the tire width direction, when an arc having a center on the tire equator line and a point of 2 land portion edges connected to the groove wall surfaces of the pair of circumferential main grooves through the tread surface of the land portion is set as a reference contour line, a contour line formed by the tread surface of the land portion is a bulging contour line that protrudes outward in the tire radial direction than the reference contour line.)
1. A pneumatic tire having a tread portion with a tread pattern,
the tread pattern includes:
a pair of circumferential main grooves including an inner circumferential main groove provided in a1 st half tread region located on one side in the tire width direction with respect to the tire equator line and an outer circumferential main groove provided on the outer side in the tire width direction with respect to the inner circumferential main groove;
a land portion demarcated in a tire width direction by the pair of circumferential main grooves; and
sipes provided in regions of the land portions, connecting the pair of circumferential main grooves, and provided in plurality at intervals in the tire circumferential direction,
each of the sipes includes a pair of inclined sipe portions that approach each other while advancing from a connecting end connected to the pair of circumferential main grooves to the 1 st side in the tire circumferential direction, and a sipe curved portion that connects ends of the pair of inclined sipe portions to each other and curves so as to protrude toward the 1 st side,
in a profile cross section of the tread portion in the tire width direction, when an arc having a center point on the tire equator line and points of 2 land portion edges respectively connected to the groove wall surfaces of the pair of circumferential main grooves through the tread surface of the land portion is set as a reference contour line,
the contour line formed by the tread surface of the land portion is a bulging contour line that protrudes outward in the tire radial direction than the reference contour line.
2. A pneumatic tire according to claim 1,
a projecting end of the sipe curved portion that projects most to the 1 st side is located within 70% of a width of the land portion in the tire width direction with a maximum projecting position of the projection contour line as a center.
3. A pneumatic tire according to claim 1 or 2,
a protruding end of the sipe curved portion that protrudes most to the 1 st side is located on the inner side in the tire width direction with respect to a maximum protruding position of the protruding contour line.
4. A pneumatic tire according to any one of claims 1 to 3,
the tread pattern includes a plurality of lateral grooves that connect the pair of circumferential main grooves and are provided at intervals in the tire circumferential direction,
each of the lateral grooves includes a pair of inclined groove portions that approach each other while proceeding from a connection end connected to the pair of circumferential main grooves toward the 1 st side in the tire circumferential direction, and a groove curved portion that connects ends of the pair of inclined groove portions to each other and curves so as to protrude toward the 1 st side in the tire circumferential direction,
the land portion is constituted by a plurality of block land portions divided in the tire circumferential direction by the lateral grooves,
2 sipes are provided as the 1 st sipe and the 2 nd sipe in each region of the land portion.
5. A pneumatic tire according to claim 4,
a projecting end of the groove curved portion that projects most to the 1 st side is located within 70% of a width of the land portion in the tire width direction with a maximum projecting position of the projection contour line as a center.
6. A pneumatic tire according to claim 4 or 5,
a projecting end of the groove curved portion that projects most to the 1 st side is located on an inner side in the tire width direction with respect to a maximum bulging position of the bulging contour line.
7. A pneumatic tire according to any one of claims 4 to 6,
the groove bending part is provided with a groove bottom rising part with the groove depth being shallower than that of the inclined groove part,
the 1 st sipe is disposed on the 1 st side with respect to the 2 nd sipe,
a1 st position in the tire width direction of a projecting end of the sipe curved portion of the 1 st sipe is located within a tire width direction bottom raised portion range in which the groove bottom raised portion is provided, and is located further toward a tire width direction inner side than a2 nd position in the tire width direction of a projecting end of the sipe curved portion of the 2 nd sipe that projects most toward the 1 st side.
8. A pneumatic tire according to claim 7,
in a region sandwiched by the 1 st sipe and the 2 nd sipe in the tire circumferential direction among the respective regions of the land portion, a3 rd sipe is provided which is inclined from the inner circumferential main groove with respect to the tire width direction and extends outward in the tire width direction in parallel with at least one of the inclined sipe portions of the 1 st sipe and the 2 nd sipe extending from the inner circumferential main groove and has a terminal end in the raised bottom portion range in the tire width direction.
9. A pneumatic tire according to any one of claims 1 to 8,
the maximum bulging amount of the bulging contour line relative to the reference contour line is in the range of 0.1-1.0 mm.
10. A pneumatic tire according to any one of claims 1 to 9,
when the land portion is referred to as a1 st intermediate land portion, the tread pattern further includes a1 st lateral land portion including a ground contact edge of the pneumatic tire in a region on the outer side in the tire width direction of the outer circumferential main groove,
a 6 th sipe connected to the outer circumferential main groove is provided in a region of the 1 st side land portion,
the 1 st sipe, the 2 nd sipe, and the 6 th sipe are each a composite sipe having a linear sipe having a shape linearly extending in a sipe depth direction from the tread surface and a wavy sipe protruding and bent or curved in a wavy shape in a direction orthogonal to a direction in which the 1 st sipe, the 2 nd sipe, and the 6 th sipe extend along the tread surface and in the sipe depth direction when advancing from the tread surface in the sipe depth direction, the linear sipe is provided on one side of the sipe extending direction as viewed from the tread surface, the wavy sipe is provided on the other side, and the composite sipe is formed by connecting the linear sipe and the wavy sipe,
the portions of the 1 st sipe, the 2 nd sipe, and the 6 th sipe connected to the outer circumferential main groove are all the wavy sipes.
11. A pneumatic tire according to any one of claims 1 to 10,
when the inner circumferential main groove is referred to as a1 st inner circumferential main groove and the outer circumferential main groove is referred to as a1 st outer circumferential main groove,
the tire is provided with, in a2 nd half tread region located on the opposite side of the 1 st half tread region in the tire width direction:
the 2 nd inner circumferential main groove;
a2 nd outer circumferential main groove provided on the tire width direction outer side with respect to the 2 nd inner circumferential main groove;
a2 nd inner circumferential main groove and a2 nd outer circumferential main groove which are defined and circumferentially surround the tire; and
a 4 th sipe and a 5 th sipe extending obliquely with respect to a tire width direction in a region of the continuous land portion and connecting the 2 nd inner circumferential main groove and the 2 nd outer circumferential main groove,
each of the 4 th sipe and the 5 th sipe includes an inner inclined portion provided inside a region of the continuous land portion, and two side inclined portions provided on both sides of the inner inclined portion in the tire width direction and connected to the 2 nd inner circumferential main groove and the 2 nd outer circumferential main groove, respectively, and an inclination angle of the inner inclined portion with respect to the tire width direction is larger than an inclination angle of the two side inclined portions with respect to the tire width direction.
12. A pneumatic tire according to claim 11,
when the continuous land portion is referred to as a2 nd intermediate land portion, the tread pattern further includes a2 nd side land portion including a ground contact edge of the pneumatic tire in a region on the outer side in the tire width direction of the 2 nd outer circumferential main groove,
a 7 th sipe connected to the 2 nd outer circumferential main groove is provided in a region of the 2 nd side land portion,
the 4 th sipe, the 5 th sipe, and the 7 th sipe are each a composite sipe having a linear sipe having a shape linearly extending in a sipe depth direction from the tread surface and a wavy sipe protruding and bent or curved in a wavy shape in a direction orthogonal to the extending direction of the tread surface and the sipe depth direction when proceeding in a sipe depth direction from the tread surface, the linear sipe being provided on one side, the wavy sipe being provided on the other side, and the composite sipe being formed by connecting the linear sipe and the wavy sipe,
the portions of the 4 th sipe, the 5 th sipe, and the 7 th sipe connected to the 2 nd outer circumferential main groove are all the wavy sipes.
13. A pneumatic tire according to any one of claims 1 to 12,
when the inner circumferential main groove is referred to as a1 st inner circumferential main groove and the outer circumferential main groove is referred to as a1 st outer circumferential main groove,
the tread pattern includes, in a2 nd half tread region located on an opposite side of the 1 st half tread region in a tire width direction:
the 2 nd inner circumferential main groove;
a2 nd outer circumferential main groove provided on the tire width direction outer side with respect to the 2 nd inner circumferential main groove;
a center continuous land portion that is divided by the 1 st inner side circumferential main groove and the 2 nd inner side circumferential main groove between the 1 st inner side circumferential main groove and the 2 nd inner side circumferential main groove and that surrounds once in the tire circumferential direction;
a1 st central lateral groove extending inward in the tire width direction from the 1 st inner circumferential main groove and terminating in the region of the central continuous land portion and provided in plurality at intervals in the tire circumferential direction; and
a2 nd central lateral groove extending inward in the tire width direction from the 2 nd inner circumferential main groove and terminating in the region of the central continuous land portion and provided in plurality at intervals in the tire circumferential direction,
1 of the 2 nd central lateral grooves are provided in a region in the tire circumferential direction between 2 adjacent 1 st of the 1 st central lateral grooves in the tire circumferential direction,
in the tire circumferential direction, 1 of the 1 st central lateral grooves is provided in a region in the tire circumferential direction between 2 adjacent 2 nd central lateral grooves among the 2 nd central lateral grooves.
14. A pneumatic tire according to claim 13,
the maximum groove depth of the 2 nd central transverse groove is shallower than the maximum groove depth of the 1 st central transverse groove.
15. A pneumatic tire according to any one of claims 1 to 14,
in the pneumatic tire, one of both sides in the tire width direction is designated as a vehicle outer side at the time of vehicle mounting,
the side in the tire width direction on which the 1 st half tread region is provided is designated as the vehicle outer side.
16. A pneumatic tire according to claim 15,
a shoulder lateral groove is provided on the tire width direction outer side of the outer circumferential main groove of the 1 st half tread region,
the tread pattern includes, in a2 nd half tread region located on an opposite side of the 1 st half tread region in a tire width direction:
the 2 nd inner circumferential main groove;
a2 nd outer circumferential main groove provided on the tire width direction outer side with respect to the 2 nd inner circumferential main groove; and
a shoulder lateral groove provided on the outer side in the tire width direction of the 2 nd outer circumferential main groove,
a groove area ratio in a region on the tire width direction outer side of the 1 st outer circumferential main groove of the 1 st half tread region is smaller than a groove area ratio in a region on the tire width direction outer side of the 2 nd outer circumferential main groove.
Technical Field
The present invention relates to a pneumatic tire.
Background
Conventionally, a tread pattern of a pneumatic tire is provided with a plurality of circumferential main grooves extending in the tire circumferential direction, and lateral grooves or sipes crossing land portions defined by 2 circumferential main grooves in the tire width direction. An all-weather pneumatic tire (hereinafter, referred to as an all-weather tire) is positioned as a tire in the middle between a usual so-called "summer tire" for a non-snow period and a snow tire called a winter tire, and is widely used in north america and europe. In this all-weather tire, since excellent drivability and braking/driving performance (snow performance) on a snowy road surface are required, a plurality of sipes and lateral grooves are provided in addition to the circumferential main groove for the purpose of increasing the edge component.
For example, a pneumatic tire is known in which uneven wear resistance in the center portion in the tread width direction is improved while ensuring on-snow performance (patent document 1).
The pneumatic tire comprises: a central circumferential main groove that is formed in a tire width direction central portion of the tread and extends in the tire circumferential direction; an outer circumferential main groove that is formed in the tread surface on the outer side in the tire width direction than and beside the central circumferential main groove and extends in the tire circumferential direction; a lateral main groove formed in the tread surface, extending in a direction intersecting the tire circumferential direction, and communicating with the central circumferential main groove and the outer circumferential main groove, respectively, the lateral main groove having a groove depth based on the tread surface that is deeper than the groove depth of the central circumferential main groove and shallower than the groove depth of the outer circumferential main groove; and a central block divided by the central circumferential main groove, the outer circumferential main groove, and the lateral main groove. In addition, a sipe is provided at the bottom of the central circumferential main groove.
Disclosure of Invention
Problems to be solved by the invention
In the pneumatic tire described above, the on-snow performance can be ensured by the edge of the center block formed by the lateral main grooves. Further, the lateral main grooves communicate with the central circumferential main groove and the outer circumferential main groove, respectively, the groove depth of the lateral main grooves is set to be shallower than the groove depth of the outer circumferential main groove, and the groove depth of the central circumferential main groove is set to be shallower than the groove depth of the lateral main grooves, so that the rigidity of the center block can be secured, excessive deformation of the center block at the time of load rolling of the tire can be suppressed, and rapid heel and toe wear in the center can be suppressed. This can ensure on-snow performance and improve uneven wear resistance in the tread width direction center portion.
The pneumatic tire has excellent uneven wear resistance, but when such a tread pattern is applied to an all-weather tire for a passenger vehicle, steering stability suitable for a dry road surface of the passenger vehicle is not necessarily exhibited.
Accordingly, an object of the present disclosure is to provide a pneumatic tire capable of improving steering stability on a dry road surface and on-snow performance by a new tread pattern different from the above-described tread pattern.
Means for solving the problems
One aspect of the present disclosure is a pneumatic tire having a tread pattern.
The tread pattern includes:
a pair of circumferential main grooves including an inner circumferential main groove provided in a1 st half tread region located on one side in the tire width direction with respect to the tire equator line and an outer circumferential main groove provided on the outer side in the tire width direction with respect to the inner circumferential main groove;
a land portion demarcated in a tire width direction by the pair of circumferential main grooves; and
sipes provided in the region of the land portion, connecting the pair of circumferential main grooves, and provided in plurality at intervals in the tire circumferential direction.
Each of the sipes includes a pair of inclined sipe portions that approach each other while advancing from a connecting end connected to the pair of circumferential main grooves to the 1 st side in the tire circumferential direction, and a sipe curved portion that connects ends of the pair of inclined sipe portions to each other and curves so as to protrude toward the 1 st side,
in a profile cross section of the tread portion in the tire width direction, when an arc having a center point on the tire equator line and points of 2 land portion edges respectively connected to the groove wall surfaces of the pair of circumferential main grooves through the tread surface of the land portion is set as a reference contour line,
the contour line formed by the tread surface of the land portion is a bulging contour line that protrudes outward in the tire radial direction than the reference contour line.
Preferably, a projecting end of the sipe curved portion that projects most to the 1 st side is located within 70% of a width of the land portion in the tire width direction with a maximum projecting position of the projection contour line as a center.
Preferably, a projecting end of the sipe curved portion that projects most to the 1 st side is located on an inner side in the tire width direction with respect to a maximum projection position of the projection profile.
Preferably, the tread pattern includes a plurality of lateral grooves connecting the pair of circumferential main grooves and provided at intervals in the tire circumferential direction,
each of the lateral grooves includes a pair of inclined groove portions that approach each other while proceeding from a connection end connected to the pair of circumferential main grooves toward the 1 st side in the tire circumferential direction, and a groove curved portion that connects ends of the pair of inclined groove portions to each other and curves so as to protrude toward the 1 st side in the tire circumferential direction,
the land portion is constituted by a plurality of block land portions divided in the tire circumferential direction by the lateral grooves,
2 sipes are provided as the 1 st sipe and the 2 nd sipe in each region of the land portion.
Preferably, a projecting end of the groove curved portion that projects most to the 1 st side is located within 70% of a width of the land portion in the tire width direction with a maximum projecting position of the projection contour line as a center.
Preferably, a projecting end of the groove curved portion that projects most to the 1 st side is located on an inner side in a tire width direction with respect to a maximum bulging position of the bulging contour line.
Preferably, the groove curved portion is provided with a groove bottom raised portion having a groove depth shallower than that of the inclined groove portion,
the 1 st sipe is disposed on the 1 st side with respect to the 2 nd sipe,
a1 st position in the tire width direction of a projecting end of the sipe curved portion of the 1 st sipe is located within a tire width direction bottom raised portion range in which the groove bottom raised portion is provided, and is located further toward a tire width direction inner side than a2 nd position in the tire width direction of a projecting end of the sipe curved portion of the 2 nd sipe that projects most toward the 1 st side.
Preferably, in a region sandwiched by the 1 st sipe and the 2 nd sipe in the tire circumferential direction among the respective regions of the land portion, a3 rd sipe that extends from the inner circumferential main groove to the tire width direction outer side while being inclined with respect to the tire width direction in parallel with at least one of the inclined sipe portions of the 1 st sipe and the 2 nd sipe extending from the inner circumferential main groove and has a terminal end in the bottom raised portion range in the tire width direction is provided.
Preferably, the maximum amount of projection of the projection profile with respect to the reference profile is in the range of 0.1 to 1.0 mm.
Preferably, when the land portion is referred to as a1 st intermediate land portion, the tread pattern further includes a1 st lateral land portion including a ground contact edge of the pneumatic tire in a region on the outer side in the tire width direction of the outer circumferential main groove,
a 6 th sipe connected to the outer circumferential main groove is provided in a region of the 1 st side land portion,
the 1 st sipe, the 2 nd sipe, and the 6 th sipe are each a composite sipe having a linear sipe having a shape linearly extending in a sipe depth direction from the tread surface and a wavy sipe protruding and bent or curved in a wavy shape in a direction orthogonal to the extending direction of the tread surface and the sipe depth direction when proceeding in a sipe depth direction from the tread surface, the linear sipe being provided on one side in the sipe extending direction as viewed from the tread surface and the wavy sipe being provided on the other side, and the composite sipe being formed by connecting the linear sipe and the wavy sipe,
the portions of the 1 st sipe, the 2 nd sipe, and the 6 th sipe connected to the outer circumferential main groove are all the wavy sipes.
Preferably, when the inner circumferential main groove is referred to as a1 st inner circumferential main groove and the outer circumferential main groove is referred to as a1 st outer circumferential main groove,
the tire is provided with, in a2 nd half tread region located on the opposite side of the 1 st half tread region in the tire width direction:
the 2 nd inner circumferential main groove;
a2 nd outer circumferential main groove provided on the tire width direction outer side with respect to the 2 nd inner circumferential main groove;
a continuous land portion that is divided by the 2 nd inner circumferential main groove and the 2 nd outer circumferential main groove and that surrounds once in the tire circumferential direction; and
a 4 th sipe and a 5 th sipe extending obliquely with respect to a tire width direction in a region of the continuous land portion and connecting the 2 nd inner circumferential main groove and the 2 nd outer circumferential main groove,
the 4 th sipe and the 5 th sipe each include an inner inclined portion provided inside a region of the continuous land portion, and two side inclined portions provided on both sides of the inner inclined portion in the tire width direction and connected to the 2 nd inner circumferential main groove and the 2 nd outer circumferential main groove, respectively, the inner inclined portion of the 4 th sipe and the inner inclined portion of the 5 th sipe are parallel to each other, and an inclination angle of the inner inclined portion with respect to the tire width direction is larger than an inclination angle of the two side inclined portions with respect to the tire width direction.
Preferably, when the continuous land portion is referred to as a2 nd intermediate land portion, the tread pattern further includes a2 nd lateral land portion including a ground contact end of the pneumatic tire in a region on the outer side in the tire width direction of the 2 nd outer circumferential main groove,
a 7 th sipe connected to the 2 nd outer circumferential main groove is provided in a region of the 2 nd side land portion,
the 4 th sipe, the 5 th sipe, and the 7 th sipe are each a composite sipe having a linear sipe having a shape linearly extending in a sipe depth direction from the tread surface and a wavy sipe protruding and bent or curved in a wavy shape in a direction orthogonal to the extending direction of the tread surface and the sipe depth direction when proceeding in a sipe depth direction from the tread surface, the linear sipe being provided on one side, the wavy sipe being provided on the other side, and the composite sipe being formed by connecting the linear sipe and the wavy sipe,
the portions of the 4 th sipe, the 5 th sipe, and the 7 th sipe connected to the 2 nd outer circumferential main groove are all the wavy sipes.
Preferably, when the inner circumferential main groove is referred to as a1 st inner circumferential main groove and the outer circumferential main groove is referred to as a1 st outer circumferential main groove,
the tread pattern includes, in a2 nd half tread region located on an opposite side of the 1 st half tread region in a tire width direction:
the 2 nd inner circumferential main groove;
a2 nd outer circumferential main groove provided on the tire width direction outer side with respect to the 2 nd inner circumferential main groove;
a center continuous land portion that is divided by the 1 st inner side circumferential main groove and the 2 nd inner side circumferential main groove between the 1 st inner side circumferential main groove and the 2 nd inner side circumferential main groove and that surrounds once in the tire circumferential direction;
a1 st central lateral groove extending inward in the tire width direction from the 1 st inner circumferential main groove and terminating in the region of the central continuous land portion and provided in plurality at intervals in the tire circumferential direction; and
a2 nd central lateral groove extending inward in the tire width direction from the 2 nd inner circumferential main groove and terminating in the region of the central continuous land portion and provided in plurality at intervals in the tire circumferential direction,
1 of the 2 nd central lateral grooves are provided in a region in the tire circumferential direction between 2 adjacent 1 st of the 1 st central lateral grooves in the tire circumferential direction,
in the tire circumferential direction, 1 of the 1 st central lateral grooves is provided in a region in the tire circumferential direction between 2 adjacent 2 nd central lateral grooves among the 2 nd central lateral grooves.
Preferably, the maximum groove depth of the 2 nd central lateral groove is shallower than the maximum groove depth of the 1 st central lateral groove.
Preferably, in the pneumatic tire, one of both sides in the tire width direction is designated as a vehicle outer side at the time of vehicle mounting,
the side in the tire width direction on which the 1 st half tread region is provided is designated as the vehicle outer side.
Preferably, a shoulder lateral groove is provided on the tire width direction outer side of the outer circumferential main groove of the 1 st half tread region,
the tread pattern includes, in a2 nd half tread region located on an opposite side of the 1 st half tread region in a tire width direction:
the 2 nd inner circumferential main groove;
a2 nd outer circumferential main groove provided on the tire width direction outer side with respect to the 2 nd inner circumferential main groove; and
a shoulder lateral groove provided on the outer side in the tire width direction of the 2 nd outer circumferential main groove,
a groove area ratio in a region on the tire width direction outer side of the 1 st outer circumferential main groove of the 1 st half tread region is smaller than a groove area ratio in a region on the tire width direction outer side of the 2 nd outer circumferential main groove.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the pneumatic tire, steering stability on a dry road surface and on-snow performance can be improved.
Drawings
Fig. 1 is a tire sectional view of a tire according to an embodiment.
Fig. 2 is a diagram illustrating a tread pattern according to an embodiment.
Fig. 3 is a diagram illustrating contour lines formed by land portions of a tire according to an embodiment.
Fig. 4 is an enlarged view illustrating the intermediate land portion and the lateral groove of the embodiment in detail.
Fig. 5(a) to (e) are views illustrating the form of a composite sipe provided in a tread pattern according to an embodiment.
Fig. 6(a) and (b) are views illustrating the form of the sipe in the sipe depth direction according to the embodiment.
Fig. 7 is a view showing a part of the tread pattern used in comparative examples 1 and 3.
Detailed Description
Hereinafter, the pneumatic tire of the present disclosure will be described in detail with reference to the drawings.
The pneumatic tire of the embodiment described below is applied to all-weather tires for passenger cars, but may also be applied to all-weather tires for small trucks or all-weather tires for buses and trucks.
In the following description, the tire width direction is a direction parallel to the rotation axis of the pneumatic tire. The tire width direction outer side is a side apart from a tire equator line CL indicating a tire equator plane with respect to a comparative position in the tire width direction. Further, the tire width direction inner side is a side closer to the tire equator line CL in the tire width direction with respect to the position of comparison. The tire circumferential direction is a direction in which the pneumatic tire rotates around the rotation axis of the pneumatic tire as a rotation center. The tire circumferential direction has a1 st side and a2 nd side which are different from each other in direction. The tire radial direction is a direction orthogonal to the rotation axis of the pneumatic tire. The tire radial direction outer side means a side apart from the rotation axis in the tire radial direction with respect to the comparison position. The tire radial direction inner side means a side closer to the rotation axis in the tire radial direction with respect to the comparison position.
In the following description, the ground contact end of the pneumatic tire refers to the end farthest from the tire equator line CL in a region where the tread surface of the tread portion of the pneumatic tire contacts a dry horizontal surface when the pneumatic tire rim is assembled to a regular rim (japanese: normal size リム), a regular internal pressure (japanese: normal size internal pressure) is applied, and 70% of a regular load (japanese: normal size load) is applied. The regular Rim is a "standard Rim (japanese: registration リム)" prescribed by JATMA, a "design Rim" prescribed by TRA, or a "Measuring Rim" prescribed by ETRTO. The normal internal pressure is a maximum value described in "maximum air pressure (japanese maximum air pressure)" defined by JATMA, "TIRE LOAD coefficients COLD INFLATION PRESSURES" defined by TRA, or "INFLATION PRESSURES" defined by ETRTO. The normal LOAD is a maximum value described in "maximum LOAD CAPACITY (japanese: maximum negative LOAD CAPACITY)" defined by JATMA, a "TIRE LOAD LIMITS at various COLD INFLATION PRESSURES" defined by TRA, or a "LOAD CAPACITY" defined by ETRTO.
(tire structure)
Fig. 1 is a tire sectional view of a
The
The carcass ply 12 is constituted by a carcass ply material wound between a pair of
A
Further, the
The tire structure of the present embodiment is as described above, but the tire structure is not particularly limited, and a known tire structure can be applied.
(Tread pattern)
Fig. 2 is a diagram illustrating an example of a tread pattern according to an embodiment. The tread pattern shown in fig. 2 described below is asymmetric with respect to the tire equator line CL, but may not necessarily be asymmetric. For example, the pattern may be point-symmetrical in which the tread pattern on the right side of the inner circumferential
As shown in fig. 2, the tread pattern of the
The inner circumferential
The
The inner circumferential
The outer circumferential
Specifically, a
The
In the region of the
In fig. 2, an
The
The
The
The lateral groove 63 extends from the outer circumferential
That is, each of the
The lateral groove 65 extends outward in the tire width direction from the outer circumferential
The lateral groove 67 extends outward in the tire width direction from the outer circumferential
The groove depths of the inner circumferential
The
Fig. 3 is a diagram illustrating the contour line of the tread surface formed by the land portions of the tread pattern shown in fig. 2.
As shown in fig. 3, the
The reference contour line PL0 includes a case where the reference contour line PL0 passes through points of 2 land portion edges and points of 1 side land portion edge, and also includes a case where the reference contour line PL0 passes through a position slightly deviated from these points. In this case, it is preferable to set the reference contour line PL0 as the line of the circular arc whose total distance from each point to the line of the circular arc is minimized. For example, in the case of a contour line having a line-symmetric shape with respect to the tire equator line CL, it is preferable that a line of an arc having a center point on the tire equator line CL and having a radius such that the sum of distances from the points of the 2 land portion edges and the points of the 1 side land portion edges located on both sides in the tire width direction is the smallest is set as the reference contour line PL 0.
On the other hand, the bulging contour lines PL1 and PL2 are contour lines that protrude outward in the tire radial direction from the reference contour line. That is, the contour lines of the
The maximum protrusion amount of the protrusion contour lines PL1 and PL2 with respect to the reference contour line PL0 is preferably 0.1 to 1.0mm, for example. By setting the maximum bulging amount to a range of 0.1 to 1.0mm, the ground contact pressure in the central regions of the
The
Although the
According to one embodiment, the projecting ends of the mountain-shaped sipe curved portions 61a2, 61b2 of the
In this case, it is preferable that the protruding ends of the sipe curved portions 60a3, 60b3 of the
As described above, since the
According to one embodiment, it is preferable that the protruding end of the groove curved portion 61a2 of the
In this case, it is preferable that the protruding end of the groove curved portion 61a2 of the
According to one embodiment, as shown in fig. 4, it is preferable that the groove bottom raised portion 61a3 (a portion of the oblique line in fig. 4) having a shallower groove depth than the groove depth of the inclined groove portion is provided in the groove bent portion 61a2 of the
In particular, the groove curved portion 61a2 that defines the
According to one embodiment, it is preferable that, in the region of each of the
As shown in fig. 2,
In other embodiments, it is preferable that the
Fig. 5(a) to (e) are views illustrating the form of a composite sipe provided in a tread pattern according to an embodiment. Fig. 6(a) and (b) are views illustrating the form of the
The
Here, as shown in fig. 6(a), the sipe S1 is a linear sipe having a shape linearly extending from the tread surface in the sipe depth direction. As shown in fig. 6(b), the sipe S2 is a wavy sipe that protrudes in a direction orthogonal to the sipe depth direction and the extending direction when viewed from the tread surface when proceeding in the sipe depth direction from the tread surface and is bent or curved in a wavy manner.
The sipe 58a provided in the region of the
As is apparent from fig. 2 and fig. 5(a) and (b), in the
As is apparent from fig. 2 and 5(c), the
As is apparent from fig. 2 and 5(d), in the
As is apparent from fig. 2 and 5E, the
The
Therefore, by disposing the wavy sipes in the portions of the
As described above, the provision of the lateral grooves 63 that do not penetrate the inner circumferential
Further, in the region of the
The maximum groove depth of the central lateral groove 59b is preferably shallower than the maximum groove depth of the central lateral groove 59 a. As shown in fig. 2, the tread pattern of the half tread region on the right side of the tire equator line CL improves the on-snow performance by enhancing the edge effect by the sipe or the lateral groove. By making the maximum groove depth of the central lateral groove 59a deeper than the maximum groove depth of the central lateral groove 59b, a large amount of snow can be caught in the central lateral groove 59a, and the edge effect can be improved, so the on-snow performance can be improved.
According to an embodiment, in the
At this time, it is preferable that the groove area ratio in the shoulder region including the side land portion 64 (1 st side land portion) at the tire width direction outer side of the outer circumferential
(examples and comparative examples)
In order to confirm the effects of the tire of the present embodiment, steering stability and on-snow performance (on-snow braking performance, on-snow steering performance) were evaluated by variously changing the tread pattern.
The structure of the tire (tire size: 265/50R 20111W) thus produced was the structure shown in FIG. 1. The manufactured tire was mounted on a rim (rim size: 20X 8.5J) (air pressure 250kPa) and was mounted on a test vehicle (SUV vehicle having an air displacement of 3.6 liters).
For evaluation of steering stability, a test vehicle was run on a predetermined dry road surface route, and the response of the test vehicle to steering by the driver was evaluated organoleptically. In the sensory evaluation, the evaluation indexes of the other comparative examples and examples were set to 100 as the index of comparative example 1. A higher index indicates more excellent steering stability.
For evaluation of braking performance on snow, a test vehicle was run on a predetermined route on a snow road surface, and the braking distance when full braking was performed from a speed of 30 km/hour was measured. The measurement results were obtained by indexing the reciprocal of the braking distance of the other comparative examples and examples based on the reciprocal of the braking distance of comparative example 1, and evaluating the on-snow braking performance. The index of comparative example 1 was 100. Therefore, a higher index indicates more excellent braking performance on snow.
In addition, with respect to the on-snow handling performance, the test vehicle was run on a predetermined on-snow road surface route, and the response of the test vehicle to the steering by the driver was evaluated organoleptically. In this sensory evaluation, the evaluation indexes of the other comparative examples and examples were also set to 100 as the index of comparative example 1. A higher index indicates more excellent handling performance on snow.
Tables 1 and 2 below show specifications of a tread pattern and evaluation results thereof, which were variously modified with reference to the tread pattern shown in fig. 2. The
The "presence or absence of the mountain-shaped sipes and the mountain-shaped lateral grooves" in tables 1 and 2 indicates whether or not the mountain-shaped
In tables 1 and 2, "position (%) from the maximum bulging position to the sipe protruding end" and "position (%) from the maximum bulging position to the lateral groove protruding end" indicate a ratio (%) obtained by dividing the distance in the tire width direction from the maximum bulging position of the bulging contour line PL1 to the positions of the
The maximum bulging amount of the bulging contour lines PL1 and PL2 with respect to the reference contour line PL0 was 0.2 mm.
The groove area ratio in the region of the
In example 8 in table 2, the groove width of the lateral groove 65 and the groove width of the lateral groove 67 are made to coincide, so that the groove area ratio in the region of the
[ Table 1]
[ Table 2]
As is clear from comparative examples 1 to 3 and examples 1 to 8, the snowy handling performance, the snowy braking performance, and the handling stability on dry roads are improved by providing mountain-shaped sipes and lateral grooves in the
As is apparent from examples 1 to 7, the protruding end of the mountain-shaped sipe is provided within 70% of the width of the
As is apparent from examples 1 and 8, steering stability on a dry road surface is improved by making the groove area ratio smaller in the shoulder region on the side of the
Although the pneumatic tire of the present invention has been described in detail above, the present invention is not limited to the above embodiments and examples, and various improvements and modifications may be made without departing from the scope of the present invention.
Description of the reference numerals
10 pneumatic tire
10T tread portion
10S side wall part
10B bead part
12 carcass ply
14 Belt layer
16 bead core
18 tread rubber component
20 side wall rubber component
22 bead filler rubber Member
24 rim cushion rubber member
26 inner liner rubber component
30 Belt overlay
50. 54 inner circumferential main groove
52. 56 outer circumferential main groove
58 center land portion
60. 62 middle land part
60a1, 60a2, 60b1, 60b2 inclined sipe portion
60a3, 60b3 sipe bend
61a1 inclined groove part
61a2 groove bend
61a3 trough bottom elevation
62a1, 62b1 steep incline section
62a2, 62b2 gently sloping portion
64. 66 side land part
59a, 59b, 61, 63, 65, 67 transverse groove
58a, 60b, 60c, 62a, 62b, 62c, 64a, 64b, 66a, 66b sipes
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