JP6939103B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving the on-ice performance of the tire at the start of use of a new tire.

In general, when a new tire is started to be used, the original function of the tread rubber is not properly exhibited, so that there is a problem that the performance on ice cannot be properly obtained. For this reason, in recent studless tires, a plurality of fine shallow grooves are arranged on the block tread in order to properly ensure the performance on ice at the start of use of a new tire. Such a narrow groove is much shallower than the sipe and has a groove depth that disappears at the initial stage of tire wear. As a conventional pneumatic tire adopting such a configuration, the technique described in Patent Document 1 is known.

Japanese Patent No. 4571482

An object of the present invention is to provide a pneumatic tire capable of improving the on-ice performance of a tire at the start of use of a new tire.

In order to achieve the above object, the pneumatic tire according to the present invention is a pneumatic tire having a plurality of blocks on the tread surface, the blocks having a plurality of uneven portions on the tread surface, and the amount of unevenness of the uneven portions. Hc is in the range of 0.1 [mm] ≤ Hc ≤ 1.0 [mm], and the width Wc of the uneven portion is in the range of 0.1 [mm] ≤ Wc ≤ 0.8 [mm]. A region in which the arrangement interval Dc of the adjacent concavo-convex portions is in the range of Dc ≦ 1.2 [mm] is defined as an concavo-convex region, which is a region other than the concavo-convex region and is the arithmetic average coarseness of the tread surface of the block. A region in which Ra is in the range of Ra ≦ 50 [μm] is defined as a smooth region, a cross section X perpendicular to the tire circumferential direction is defined, and the circumferential length Lb of the tread surface of the block in the tire circumferential direction. defines the block, at any cross-section X in the circumferential range 40% or more of the circumferential length Lb of the tread of the block, two or more of the irregular region and two or more of the smooth region possess respectively, and one of the irregular region in the section X, characterized in that comprising a plurality of the uneven portions.
Further, the pneumatic tire according to the present invention is a pneumatic tire having a plurality of blocks on the tread surface, the blocks having a plurality of uneven portions on the tread surface, and the unevenness amount Hc of the uneven portions is 0. The width Wc of the uneven portion is in the range of 1 [mm] ≤ Hc ≤ 1.0 [mm], and the width Wc of the uneven portion is in the range of 0.1 [mm] ≤ Wc ≤ 0.8 [mm]. A region in which the arrangement interval Dc of the portions is in the range of Dc ≦ 1.2 [mm] is defined as a concavo-convex region, and the region other than the concavo-convex region, the arithmetic average roughness Ra of the tread surface of the block is Ra ≦ Ra ≦. A region in the range of 50 [μm] is defined as a smooth region, a cross section X perpendicular to the tire circumferential direction is defined, and a circumferential length Lb of the tread surface of the block in the tire circumferential direction is defined. The block has the uneven region and the smoothed region in an arbitrary cross section X in a circumferential range of 40 [%] or more of the circumferential length Lb of the tread of the block, and the uneven portion has a concave-convex region. It is characterized by having an aspherical and long structure.
Further, the pneumatic tire according to the present invention is a pneumatic tire having a plurality of blocks on the tread surface, the blocks having a plurality of uneven portions on the tread surface, and the unevenness amount Hc of the uneven portions is 0. The width Wc of the uneven portion is in the range of 1 [mm] ≤ Hc ≤ 1.0 [mm], and the width Wc of the uneven portion is in the range of 0.1 [mm] ≤ Wc ≤ 0.8 [mm]. A region in which the arrangement interval Dc of the portions is in the range of Dc ≦ 1.2 [mm] is defined as a concavo-convex region, and the region other than the concavo-convex region and the arithmetic average roughness Ra of the tread surface of the block is Ra ≦ Ra ≦. A region in the range of 50 [μm] is defined as a smooth region, a cross section X perpendicular to the tire circumferential direction is defined, and a circumferential length Lb of the tread surface of the block in the tire circumferential direction is defined. The block has the uneven region and the smoothed region in an arbitrary cross section X in a circumferential range of 40 [%] or more of the circumferential length Lb of the tread of the block, and the width of the concave-convex region. W1 and the width W2 of the smoothing region adjacent to the uneven region have a relationship of 0.50 ≦ W1 / W2 ≦ 1.50.

Since the pneumatic tire according to the present invention includes the uneven region A1 composed of fine uneven portions in which the treads of the blocks are densely arranged, the uneven region absorbs and removes the water film on the icy road surface. Further, since the tread surface of the block has a flat smooth region, the contact area of the block with respect to the icy road surface is secured. Since the uneven region and the smooth region are arranged in a mixed manner, the adhesive frictional force of the smooth region with respect to the icy road surface is improved. This has the advantage that the ground contact characteristics of the block with respect to the icy road surface are improved, and the performance on ice of the tire is synergistically improved.

FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view showing the tread surface of the pneumatic tire shown in FIG. FIG. 3 is a plan view showing the tread surface of the block shown in FIG. FIG. 4 is an enlarged view showing the tread surface of the block shown in FIG. FIG. 5 is an X-view cross-sectional view showing the tread surface of the block shown in FIG. FIG. 6 is a cross-sectional view taken along the line PP of the uneven portion shown in FIG. FIG. 7 is a cross-sectional view taken along the line Q of the uneven portion shown in FIG. FIG. 8 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 9 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 10 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 11 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 12 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 13 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 14 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 15 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 16 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 17 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 18 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 19 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 20 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 21 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 22 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 23 is an explanatory view showing a modified example of the tread surface of the block shown in FIG. FIG. 24 is an enlarged view showing a modified example of the arrangement structure of the uneven portion described in FIG. FIG. 25 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 26 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 27 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 28 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 29 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 30 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 31 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 32 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 33 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 34 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 35 is an enlarged view showing a modified example of the arrangement structure of the uneven portion shown in FIG. FIG. 36 is an explanatory view showing a modified example of the uneven portion shown in FIGS. 5 and 6. FIG. 37 is an explanatory view showing a modified example of the uneven portion shown in FIGS. 5 and 6. FIG. 38 is an explanatory view showing a modified example of the uneven portion shown in FIGS. 5 and 6. FIG. 39 is an explanatory view showing a modified example of the uneven portion shown in FIGS. 5 and 6. FIG. 40 is a plan view showing a modified example of the tread surface shown in FIG. FIG. 41 is a plan view showing the tread surface of the block shown in FIG. 40. FIG. 42 is a plan view showing the tread surface of the block shown in FIG. 40. FIG. 43 is a plan view showing the tread surface of the block shown in FIG. 40. FIG. 44 is a chart showing the results of a performance test of a pneumatic tire according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components of this embodiment include those that are replaceable and self-explanatory while maintaining the identity of the invention. Further, the plurality of modifications described in this embodiment can be arbitrarily combined within a range self-evident by those skilled in the art.

[Pneumatic tires]
FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. The figure shows a cross-sectional view of one side region in the tire radial direction. Further, the figure shows a radial tire for a passenger car as an example of a pneumatic tire.

In the figure, the cross section in the tire meridian direction means a cross section when a tire is cut on a plane including a tire rotation axis (not shown). Further, the symbol CL is a tire equatorial plane, and refers to a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. The tire width direction means a direction parallel to the tire rotation axis, and the tire radial direction means a direction perpendicular to the tire rotation axis.

The pneumatic tire 1 has an annular structure centered on a tire rotation axis, and has a pair of bead cores 11 and 11, a pair of bead fillers 12 and 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. , A pair of sidewall rubbers 16 and 16, and a pair of rim cushion rubbers 17 and 17 (see FIG. 1).

The pair of bead cores 11 and 11 is an annular member formed by bundling a plurality of bead wires, and constitutes the cores of the left and right bead portions. The pair of bead fillers 12 and 12 are arranged on the outer periphery of the pair of bead cores 11 and 11 in the tire radial direction to form a bead portion.

The carcass layer 13 has a single-layer structure composed of one carcass ply or a multi-layer structure formed by laminating a plurality of carcass plies, and is bridged between the left and right bead cores 11 and 11 in a toroidal shape to form a tire skeleton. Constitute. Further, both ends of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with coated rubber and rolling them, and has an absolute value of 80. It has a carcass angle of [deg] or more and 95 [deg] or less (inclination angle of the carcass cord in the fiber direction with respect to the tire circumferential direction).

The belt layer 14 is formed by laminating a pair of intersecting belts 141 and 142 and a belt cover 143, and is arranged so as to be hung around the outer circumference of the carcass layer 13. The pair of crossing belts 141 and 142 are formed by coating a plurality of belt cords made of steel or an organic fiber material with coated rubber and rolling them, and have an absolute value of 20 [deg] or more and 55 [deg] or less. Have. Further, the pair of crossing belts 141 and 142 have differently signed belt angles (inclination angles of the belt cords in the fiber direction with respect to the tire circumferential direction), and the belt cords are laminated so as to cross each other in the fiber directions. (Cross-ply structure). The belt cover 143 is formed by rolling a plurality of cords made of steel or an organic fiber material coated with a coated rubber, and has a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. Further, the belt covers 143 are laminated and arranged on the outer side of the cross belts 141 and 142 in the tire radial direction.

The tread rubber 15 is arranged on the outer periphery of the carcass layer 13 and the belt layer 14 in the tire radial direction to form a tread portion of the tire. The pair of sidewall rubbers 16 and 16 are arranged on the outer side of the carcass layer 13 in the tire width direction, respectively, to form the left and right sidewall portions. The pair of rim cushion rubbers 17 and 17 are arranged inside the left and right bead cores 11 and 11 and the rewinding portion of the carcass layer 13 in the tire radial direction, respectively, and form contact surfaces of the left and right bead portions with respect to the rim flange.

[Tread pattern]
FIG. 2 is a plan view showing the tread surface of the pneumatic tire shown in FIG. The figure shows, as an example, a simple tread pattern in which grooves are arranged in a grid pattern. In the figure, the tire circumferential direction means the direction around the tire rotation axis. Further, reference numeral T is a tire ground contact end.

As shown in FIG. 2, the pneumatic tire 1 is provided with a plurality of grooves 2a and 2b and a block 4 partitioned into these grooves 2a and 2b in the tread portion.

The grooves 2a and 2b are grooves that define the block 4, and have a groove width of 2.0 [mm] or more and a groove depth of 3.0 [mm] or more.

The groove width is measured as the maximum value of the distance between the left and right groove walls at the groove opening in a no-load state in which the tire is mounted on the specified rim and the specified internal pressure is filled. In a configuration in which the land portion has a notch or a chamfered portion at the edge portion, the groove width is measured at the intersection of the tread tread and the extension line of the groove wall in a cross-sectional view in which the groove length direction is the normal direction. Is measured. Further, in the configuration in which the grooves extend in a zigzag shape or a wavy shape in the tire circumferential direction, the groove width is measured with the center line of the amplitude of the groove wall as a measurement point.

The groove depth is measured as the maximum value of the distance from the tread tread to the groove bottom in a no-load state in which the tire is mounted on the specified rim and the specified internal pressure is filled. Further, in a configuration in which the groove has a partially uneven portion or a sipe on the groove bottom, the groove depth is measured by excluding these.

The specified rim means the "applicable rim" specified in JATTA, the "Design Rim" specified in TRA, or the "Measuring Rim" specified in ETRTO. The specified internal pressure means the "maximum air pressure" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or "INFLATION PRESSURES" specified in ETRTO. The specified load means the "maximum load capacity" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or the "LOAD CAPACITY" specified in ETRTO. However, in JATTA, in the case of a passenger car tire, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

The block 4 is a land portion divided into grooves 2a and 2b having the above-mentioned predetermined groove width and groove depth, and has a tread surface in the ground contact region of the tire. Further, the block 4 may have a sipe 5 (see FIG. 3 described later) on the tread surface, or may have a chamfered portion or a notch portion (not shown) on the edge portion. Further, the block 4 may have a narrow groove and a shallow groove (not shown) not included in the grooves 2a and 2b described above on the tread surface.

The tread of the block is defined as the outer surface of the block in the region between the left and right tire ground contact ends T, T (ie, the tire ground contact region).

The tire ground contact end T is a contact surface between the tire and the flat plate when the tire is mounted on the specified rim to apply a specified internal pressure and the tire is placed perpendicular to the flat plate in a stationary state and a load corresponding to the specified load is applied. It is defined as the maximum width position in the tire axial direction in.

Further, it is preferable that the length Wb of the block 4 in the width direction is in the range of 0.10 ≦ Wb / TW with respect to the tire contact width TW. As a result, the ground contact width of the block 4 (dimension symbols omitted in the drawing) is properly secured.

The length Wb in the width direction of the block is measured as the maximum width of the tread surface of the block in the width direction of the tire when the tire is mounted on the specified rim to apply the specified internal pressure and the load is not applied.

The tire contact width TW is measured as the maximum distance in the tire axial direction of the left and right tire contact ends.

For example, in the configuration of FIG. 2, the groove 2a is a circumferential main groove and extends continuously over the entire circumference of the tire. Further, four main grooves 2a in the circumferential direction having a straight shape are arranged symmetrically with respect to the tire equatorial plane CL. Further, the groove 2b is a through lug groove, which penetrates the tread surface in the tire width direction and opens to the left and right tire contact ends T. Further, a plurality of grooves 2a and 2b are arranged in a grid pattern and communicate with each other, so that five block rows are partitioned in the tire width direction.

The main groove is a groove that is obliged to display a wear indicator specified in JATTA, and has a groove width of 4.0 [mm] or more and a groove depth of 6.5 [mm] or more.

In the configuration of FIG. 2, the groove 2a has a straight shape as described above, but the groove 2a has a zigzag shape or a wavy shape extending in the tire circumferential direction while being bent or curved. May be used (not shown).

[Block Sipe]
FIG. 3 is a plan view showing the tread surface of the block shown in FIG. The figure shows a single block 4 partitioned by grooves 2a and 2b (see FIG. 2).

As shown in FIG. 3, in the pneumatic tire 1, the block 4 has a plurality of sipes 5, respectively. These sipes 5 increase the edge component of the block 4 to improve the on-ice performance and the on-snow performance of the tire.

The sipe is a notch formed in the land portion, and has a sipe width of less than 1.0 [mm] and a sipe depth of 2.0 [mm] or more, so that the sipe is closed when the tire touches the ground. The upper limit of the sipe depth is not particularly limited, but is generally shallower than the groove depth of the main groove.

The sipe width is measured as the maximum value of the sipe opening width on the tread surface of the land in a no-load state in which the tire is mounted on the specified rim and the specified internal pressure is filled.

The sipe depth is measured as the maximum value of the distance from the tread tread to the bottom of the sipe in the no-load state where the tire is mounted on the specified rim and the specified internal pressure is filled. Further, in the configuration in which the sipe has a partially uneven portion at the groove bottom, the sipe depth is measured excluding these.

Further, the sipe 5 has a closed structure (see FIG. 3) that terminates inside the block 4 at both ends, opens at the edge of the block 4 at one end, and inside the block 4 at the other end. It may have either a semi-closed structure (not shown) terminating with, or an open structure (not shown) that opens at the edges of the block 4 at both ends. Further, the length, the number of sheets, and the arrangement structure of the sipes 5 in the block 4 can be appropriately selected within a range self-evident by those skilled in the art. Further, the sipe 5 can extend in any direction of the tire width direction, the tire circumferential direction, and the direction in which the sipe 5 is inclined.

For example, in the configuration of FIG. 3, one block 4 includes a plurality of sipes 5. Further, these sipes 5 have a closed structure that terminates inside the block 4 at both ends, and also have a zigzag shape that extends in the tire width direction. Further, the sipes 5 are arranged in parallel at predetermined intervals in the tire circumferential direction, and two rows of sipes 5 groups are arranged in the left and right regions with the central portion of the block 4 as a boundary.

[Uneven part of the block]
FIG. 4 is an enlarged view showing the tread surface of the block shown in FIG. FIG. 5 is an X-view cross-sectional view showing the tread surface of the block shown in FIG. 6 and 7 are a cross-sectional view taken along the line PP (FIG. 6) and a cross-sectional view taken along the line Q (FIG. 7) of the uneven portion shown in FIG. In these figures, FIGS. 4 and 5 show the arrangement structure of the uneven portion 6 on the tread surface of the block 4, and FIGS. 6 and 7 show the cross-sectional shape of the uneven portion 6 in the depth direction.

As shown in FIG. 3, the block 4 is provided with a plurality of fine uneven portions 6 on the tread surface.

The uneven portion 6 is a fine surface processed portion formed on the tread surface of the block 4. Specifically, the uneven portion 6 includes a fine concave portion such as a fine shallow groove and a fine dimple, and a fine convex portion such as a fine fine rib and a fine protrusion. On the other hand, the uneven portion 6 does not include, for example, a deep narrow groove, a sipe that closes when the tire touches the ground, a deep dimple, a notch, and the like. Conceptually, a dimple having a long structure corresponds to a groove, and a protrusion having a long structure corresponds to a rib.

In the above configuration, since the treads of the block 4 are densely arranged with fine uneven portions 6, the ground contact characteristics of the block 4 with respect to the icy road surface are improved, and the performance on ice of the tire is improved. Specifically, (1) when the uneven portion 6 is a fine concave portion, the uneven portion 6 absorbs and removes the water film on the icy road surface when traveling on the icy road surface. As a result, the adhesion of the tread surface of the block 4 to the icy road surface (so-called adhesive friction force) is improved, and the performance of the tire on ice at the start of use of the new tire is improved. Further, (2) when the uneven portion 6 is a fine convex portion, the uneven portion 6 is worn out at an early stage, and the initial wear of the tread surface of the block 4 is promoted. As a result, the ground contact characteristics of the tread rubber are properly exhibited, and the on-ice performance of the tire at the start of use of the new tire is improved.

Further, the uneven amount Hc of the uneven portion 6 (see FIGS. 6 and 7) is preferably in the range of 0.1 [mm] ≤ Hc ≤ 1.0 [mm], and 0.2 [mm] ≤ Hc. More preferably, it is in the range of ≦ 0.6 [mm]. By the above lower limit and upper limit, the action of the fine uneven portion 6 is properly ensured.

The unevenness amount Hc of the uneven portion is measured as a distance from the flat surface of the block tread to the maximum depth position or the maximum height position of the outer surface of the uneven portion. Specifically, when the uneven portion is a fine concave portion, the maximum depth position of the uneven portion is the measurement point of the uneven amount Hc (see FIG. 6). When the uneven portion is a fine convex portion, the maximum height position of the uneven portion is the measurement point for the uneven amount Hc (not shown).

Further, the width Wc of the uneven portion (see FIGS. 4 and 6) is preferably in the range of 0.1 [mm] ≤ Wc ≤ 0.8 [mm], and 0.2 [mm] ≤ Wc ≤ 0. More preferably, it is in the range of .5 [mm]. By the above lower limit and upper limit, the action of the fine uneven portion 6 is properly ensured.

The width Wc of the uneven portion is measured with the intersection of the flat surface of the block tread and the outer surface of the uneven portion as a measurement point. Specifically, when the uneven portion is a fine concave portion, the width Wc is measured with the opening edge of the uneven portion with respect to the plane of the block tread as a measurement point (see FIG. 6). When the uneven portion is a fine convex portion, the width Wc is measured with the rising portion of the side wall of the uneven portion on the plane of the block tread as a measurement point. Further, when the aspect ratio of the uneven portion on the block tread is 1.50 or more, that is, when the uneven portion has a long structure, the width Wc of the uneven portion is the unevenness in the direction orthogonal to the longitudinal direction of the uneven portion. It is measured as the maximum width of the part (see FIG. 4). When the aspect ratio of the uneven portion is less than 1.50, the width Wc of the uneven portion is measured as the maximum outer diameter of the uneven portion.

For example, in the configuration of FIG. 3, the uneven portion 6 of the block 4 is composed of a shallow groove. Further, a plurality of fine shallow grooves are densely arranged to form a band-shaped region A1 composed of a group of fine shallow grooves. Further, the plurality of regions A1 are arranged in parallel in the tire width direction while the longitudinal direction is directed to the tire circumferential direction. Further, the region A2 having no shallow groove is arranged between the adjacent regions A1 and A1. Further, the region A1 composed of a group of shallow grooves and the region A2 having no shallow grooves are alternately arranged in a predetermined direction. As a result, a group of fine shallow grooves are arranged in a striped pattern on the tread surface of the block 4. These areas A1 and A2 will be described later.

Further, in the configuration of FIG. 4, the shallow groove has a straight shape in the plan view of the tread surface of the block 4. However, the present invention is not limited to this, and the shallow groove may have an arc shape, a wavy shape, or another curved shape, or may have a V shape, a zigzag shape, a step shape, or another bent shape ( Not shown).

Further, in the configuration of FIG. 4, the shallow groove has a constant width Wc and depth Hc (see FIG. 6) as a whole. However, the present invention is not limited to this, and the width Wc and the depth Hc of the uneven portion 6 may change.

Further, the groove width Wc of the fine shallow groove is preferably in the range of 0.1 [mm] or more and 0.8 [mm] or less, and preferably in the range of 0.3 [mm] or more and 0.6 [mm] or less. More preferably. By the above lower limit, the water film removing action of the fine shallow groove is ensured. Further, by the above upper limit, the rigidity of the ground contact region between the adjacent shallow grooves is ensured.

Further, the groove depth Hc of the fine shallow groove is preferably in the range of 0.1 [mm] or more and 1.0 [mm] or less, and preferably in the range of 0.2 [mm] or more and 0.5 [mm] or less. It is more preferable to be in. By the above lower limit, the water film removing action of the fine shallow groove is ensured. With the above upper limit, the rigidity of the ground contact region between the adjacent shallow grooves is ensured. In particular, since the fine shallow groove has a groove depth Hc shallower than that of the sipe 5, the block 4 remains open without being blocked when the block 4 is grounded. As a result, the water film removing action of the fine shallow groove when the block 4 is grounded is ensured.

Further, in the configuration of FIG. 4, the longitudinal direction of the shallow groove is inclined at a predetermined inclination angle (dimension symbols omitted in the drawing) with respect to the tire circumferential direction. The inclination angle of the fine shallow groove is preferably in the range of 20 [deg] or more and 70 [deg] or less, and more preferably in the range of 30 [deg] or more and 60 [deg] or less. As a result, the action of removing the water film on the icy road surface by the shallow groove is properly ensured. The inclination angle of the shallow groove is measured as an angle formed by a straight line connecting the left and right ends of one continuous shallow groove in the tire circumferential direction.

Further, in the configuration of FIG. 4, a group of fine shallow grooves constituting the region A1 are arranged at a constant pitch (dimension symbols omitted in the drawing). However, the present invention is not limited to this, and the pitch of the shallow groove may change (not shown). Further, the pitch of the fine shallow groove is preferably in the range of 0.5 [mm] or more and 2.0 [mm] or less, and preferably in the range of 0.7 [mm] or more and 1.4 [mm] or less. Is more preferable. The rigidity of the block 4 is ensured by the above lower limit. By the above upper limit, the arrangement density of the fine shallow groove is secured, and the water film removing action of the fine shallow groove is ensured. The pitch of the fine shallow grooves can be calculated as the sum of the width Wc of the fine shallow grooves described later and the arrangement interval Dc of the adjacent fine shallow grooves.

Further, as shown in FIGS. 5 and 6, the shallow groove has an arcuate cross-sectional shape in a cross-sectional view in the groove width direction. However, the present invention is not limited to this, and the shallow groove may have a rectangular cross-sectional shape (not shown). Further, the groove depth of the shallow groove may gradually decrease at the end of the shallow groove (see FIG. 7), or may decrease in steps (not shown).

[Concavo-convex area and smooth area]
Here, a region in which the arrangement interval Dc (see FIG. 6) of the adjacent uneven portions 6 and 6 is in the range of Dc ≦ 1.2 [mm] is defined as the concave-convex region A1. That is, the concavo-convex region A1 is defined as an arrangement region of a group of concavo-convex portions 6 that are densely arranged at narrow arrangement intervals. As a result, the water film removing action of the uneven portion 6 in the uneven region A1 is properly ensured.

The arrangement interval Dc of the concavo-convex portion is the distance between the concavo-convex portions adjacent to each other, and is measured at any set of concavo-convex portions adjacent to each other. Further, the arrangement interval Dc is measured with the intersection of the flat surface of the block tread and the outer surface of the uneven portion as a measurement point (see FIG. 6).

Further, in the uneven region A1, the arrangement interval Dc of the uneven portion 6 and the width Wc of the uneven portion 6 preferably have a relationship of 0.80 ≦ Dc / Wc, and have a relationship of 1.50 ≦ Dc / Wc. Is more preferable. That is, it is preferable that the adjacent concavo-convex portions 6 and 6 are not continuous and a flat flat surface is formed between the adjacent concavo-convex portions 6 and 6. As a result, the ground contact area inside the uneven region A1 is secured, and the ground contact characteristic of the concave-convex region A1 itself is improved. The upper limit of the ratio Dc / Wc is restricted by the upper limit Dc ≦ 1.2 [mm] of the arrangement interval Dc.

Further, the area ratio of the uneven portion 6 in the uneven region A1 is preferably in the range of 20 [%] or more and 45 [%] or less, and preferably in the range of 25 [%] or more and 40 [%] or less. More preferred. As a result, the water film removing action of the uneven portion 6 in the uneven region A1 is more appropriately ensured.

The area ratio of the uneven portion is calculated as a ratio of the total area occupied by the uneven portion in the plan view of the tread surface of the block 4 to the area of the entire uneven portion A1. For example, when the uneven portion 6 is a concave portion, the ratio of the total opening area to the total area of the concave-convex region A1 is calculated as the area ratio of the concave-convex portion.

Further, a region other than the above-mentioned uneven region A1 in which the arithmetic average roughness Ra of the tread surface of the block 4 is in the range of Ra ≦ 50 [μm] is defined as the smooth region A2. That is, the smooth region A2 is defined as a flat region having no grooves, sipes, or fine irregularities. The smoothing region A2 is arranged to properly secure the contact area between the tread surface and the road surface of the block 4 when the tire touches the ground.

The arithmetic mean roughness Ra is measured according to JIS B0601.

The smooth region A2 may have a plain tread surface that has not been surface-processed, or may have a tread surface that has surface processing that is interspersed with a large number of hemispherical microprojections. In such surface processing, the maximum height of the minute protrusions is in the range of 1 [μm] or more and 50 [μm] or less, and the maximum outer diameter of the fine protrusions is in the range of 1 [μm] or more and 50 [μm] or less. It is in. Further, it is preferable that the average distance between the tops of adjacent minute protrusions is in the range of 5 [μm] or more and 100 [μm] or less. Further, the maximum height and the maximum outer diameter of the minute protrusions are measured using, for example, a microscope, with the intersection of the minute protrusions and the flat surface portion of the block tread as a measurement point.

Further, the tread surface of the block 4 may include an intermediate region that does not correspond to any of the above-mentioned uneven region A1 and smooth region A2. Therefore, the uneven region A1 and the smooth region A2 may be adjacent to each other (see FIG. 3), or may have an intermediate region A3 between them (not shown).

Specifically, the arrangement position (that is, the local arrangement area) of the uneven portion 6 having the uneven amount Hc less than 0.1 [mm] and more than 50 [μm] is the above-mentioned uneven region A1 and smooth region A2. Not included in either (not shown). At the arrangement position of the uneven portion 6, the water film removing action of the uneven portion 6 in the uneven region A1 is not properly obtained, and the contact area between the tread surface and the road surface of the block 4 in the smooth region A2 is appropriate. The effect of securing the water cannot be obtained.

Similarly, the arrangement position of the uneven portion 6 (for example, a deep groove, a notch, a sipe, etc.) having an uneven amount Hc exceeding 1.0 [mm] or a width Wc exceeding 0.8 [mm] is described above. The uneven region A1 and the smooth region A2 are not formed. At such an arrangement position of the uneven portion 6, the original function of the uneven portion 6 at the initial stage of wear of the tire cannot be obtained, and the uneven portion 6 remains until the middle stage of wear.

Further, even when the uneven portion 6 has the above-mentioned predetermined uneven amount Hc and width Wc, when the arrangement interval Dc of the uneven portion 6 exceeds 1.2 [mm], that is, the uneven portion 6 is dispersed. When they are sparsely arranged, the uneven portion 6 does not form the uneven region A1 described above. The single uneven portions 6 arranged in a dispersed manner do not properly obtain the water film removing action in the uneven region A1 described above.

The boundary line of the uneven region A1 is drawn as follows (see FIG. 4). First, in the plan view of the block tread, a flat surface having a width exceeding 1.2 [mm] is selected. Then, the concavo-convex portion 6 having the predetermined concavo-convex amount Hc and the width Wc described above is extracted from the flat surface, and further, a group of concavo-convex portions 6 densely arranged at the predetermined arrangement interval Dc described above are formed. Be selected. Then, the outermost ends and edges of the selected group of concavo-convex portions 6 are connected by straight line segments, and the set of these line segments is approximated by a smooth straight line or curve to form the concavo-convex region A1. Borders are drawn. In addition, contour lines of other uneven portions (for example, deep grooves, notches, sipes, etc.) in the region are drawn and excluded from the uneven region A1.

The boundary line of the smooth region A2 is drawn as follows (see FIG. 4). First, a region excluding the uneven region A1 is extracted from the block tread, and a region in which the arithmetic mean roughness Ra of the block tread is in the range of Ra ≦ 50 [μm] is selected. Then, the outer edges of the selected regions are connected by straight line segments, and the set of these line segments is approximated by a smooth straight line or curve, and the boundary line of the smooth region A2 is drawn. In addition, contour lines of other uneven portions (for example, deep grooves, notches, sipes, etc.) in the region are drawn and excluded from the smooth region A2.

Further, a cross section X perpendicular to the tire circumferential direction is defined.

At this time, the uneven region A1 and the smooth region A2 are mixed in an arbitrary cross section X in the circumferential direction range of 40 [%] or more (preferably 50 [%] or more) of the circumferential length Lb of the tread of the block 4. And are placed. Therefore, the uneven region A1 and the smooth region A2 are arranged in a mixed manner in a predetermined circumferential range of the tread surface of the block 4.

The circumferential length Lb is measured as the maximum length of the block tread when the tire is mounted on the specified rim to apply the specified internal pressure and the load is not applied.

The circumferential range may be continuous or discontinuous. Therefore, when the tread surface of the block is scanned in the tire circumferential direction, the cross section X may satisfy the above condition in the circumferential direction range of the total circumferential length Lb of 40 [%] or more.

Further, in an arbitrary cross section X of the circumferential direction range, the width W1 of the uneven region A1 is in the range of 1.0 [mm] ≦ W1, and the width W2 of the smooth region A2 is 2.0 [mm] ≦ W2. It is preferably in the range of 3.0 [mm] ≤ W1 ≤ 8.0 [mm] and 4.0 [mm] ≤ W2 ≤ 10.0 [mm]. As a result, the functions of the uneven region A1 and the smooth region A2 are effectively exhibited.

The widths W1 and W2 of the region are measured on the cross section X. When the uneven region A1 and the smooth region A2 include the intermediate region A3, the width obtained by subtracting the width of the intermediate region A3 is calculated as the region widths W1 and W2.

Further, in the above configuration, it is preferable that the width W1 of the uneven region A1 and the width W2 of the smooth region A2 adjacent to the uneven region A1 have a relationship of 0.50 ≦ W1 / W2 ≦ 1.50. It is more preferable to have a relationship of 0.70 ≦ W1 / W2 ≦ 1.20 (see FIG. 3). That is, it is preferable that the widths W1 and W2 of the concavo-convex region A1 and the smooth region A2 that are adjacent to each other are set to be substantially the same. As a result, the effect of the mixed arrangement of the uneven region A1 and the smooth region A2 can be effectively obtained.

Further, the arrangement interval Dc of the uneven portion 6 in the uneven region A1 and the width W2 of the smooth region A2 preferably have a relationship of 4.0 ≦ W2 / Dc, and have a relationship of 8.0 ≦ W2 / Dc. Is more preferable (see FIG. 4). As a result, the action of the mixed arrangement of the uneven region A1 and the smooth region A2 can be appropriately obtained. The upper limit of the ratio W2 / Dc is not particularly limited, but is restricted by other conditions.

Further, it is preferable that the total sum ΣW1 of the width W1 of the uneven region A1 and the length Wb'of the tread surface of the block 4 in the cross section X have a relationship of 0.20 ≦ ΣW1 / Wb', and 0.40 ≦ ΣW1 /. It is more preferable to have a Wb'relationship. Similarly, the total sum ΣW2 of the width W2 of the smooth region A2 and the length Wb'of the tread surface of the block 4 at the arrangement position of the smooth region A2 preferably have a relationship of 0.20 ≦ ΣW2 / Wb', and are 0. It is more preferable to have a relationship of .40 ≦ ΣW2 / Wb'. As a result, the total width of the uneven region A1 and the smooth region A2 in a predetermined circumferential range is appropriately secured. The upper limits of the ratios ΣW1 / Wb'and ΣW2 / Wb' are not particularly limited, but are restricted by other conditions.

In the above configuration, (1) since the uneven region A1 composed of the fine uneven portions 6 in which the treads of the block 4 are densely arranged is provided, the uneven region A1 absorbs and removes the water film on the icy road surface. Further, since the tread surface of the block 4 includes the flat smoothing region A2, the contact area of the block 4 with respect to the icy road surface is secured. Since the uneven region A1 and the smooth region A2 are arranged in a mixed manner, the adhesive frictional force of the smooth region A2 with respect to the icy road surface is improved. As a result, the ground contact characteristic of the block 4 with respect to the icy road surface is improved, and the performance on ice of the tire is synergistically improved.

In particular, (2) when the vehicle turns, the tread surface of the block 4 slides in the tire width direction and touches the icy road surface. At this time, since the uneven region A1 and the smooth region A2 are arranged in a mixed manner in the tire width direction (that is, on the cross section X perpendicular to the tire circumferential direction), the synergistic action of the uneven region A1 and the smooth region A2 causes the uneven region A1 and the smooth region A2 to act synergistically. The grounding characteristics of the block 4 are improved. As a result, the turning performance on ice of the tire is efficiently improved.

For example, in the configuration of FIG. 3, the uneven region A1 and the smooth region A2 have a long strip-shaped structure in the tire circumferential direction. Further, the uneven region A1 and the smooth region A2 have a rectangular shape having constant widths W1 and W2. Further, the uneven region A1 and the smooth region A2 continuously extend from one end of the tread of the block 4 in the tire circumferential direction to the other end, and cross the tread of the block 4 in the tire circumferential direction. There is.

Further, in FIG. 3, the angle θ formed by the longitudinal center line of the concave-convex region A1 long in the tire circumferential direction and the tire circumferential direction is in the range of −15 [deg] ≤ θ ≤ 15 [deg]. Is preferable, and more preferably it is in the range of −10 [deg] ≦ θ ≦ 10 [deg]. As a result, the angle θ in the longitudinal direction of the uneven region A1 is optimized, and the function of the uneven region A1 is properly secured.

Further, in the configuration of FIG. 3, a plurality of uneven regions A1 are arranged in parallel in the tire width direction. Further, the adjacent uneven regions A1 and A1 are separated from each other. Further, a smoothing region A2 is arranged between the adjacent uneven regions A1 and A1. Further, the tread surface of the block 4 includes four uneven regions A1 and five smoothing regions A2, and these uneven regions A1 and smooth regions A2 are alternately arranged in the tire width direction. Further, the smoothing region A2 is arranged at each of the left and right edge portions of the tread surface of the block 4 in the tire width direction. Further, the plurality of concavo-convex regions A1 have a constant width W1, and the smoothing region A2 arranged between the adjacent concavo-convex regions A1 and A1 has a constant width W2.

In the above configuration, the smoothing regions A2 are arranged between the adjacent uneven regions A1 and A1, so that the adjacent uneven regions A1 and A1 absorb the water film on the icy road surface before, after, or to the left and right of the smoothing regions A2. As a result, the adhesive frictional force of the smooth region A2 with respect to the icy road surface is improved, and the performance of the tire on ice is further improved. Further, by arranging the three or more uneven regions A1 in a striped pattern with the smooth region A2 sandwiched between them, the adhesive frictional force of the smooth region A2 with respect to the icy road surface is further improved.

[Modification example]
8 to 23 are explanatory views showing a modified example of the tread surface of the block shown in FIG. In these figures, the same components as those shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

For example, in the configuration of FIG. 3, as described above, the uneven region A1 and the smooth region A2 have a long strip-shaped structure in the tire circumferential direction. Further, the uneven region A1 and the smooth region A2 continuously extend from one end of the tread of the block 4 in the tire circumferential direction to the other end, and cross the tread of the block 4 in the tire circumferential direction. There is.

On the other hand, in the configuration of FIG. 8, the uneven region A1 is shorter than the length Lb of the tread surface of the block 4, is arranged at the center of the tread surface of the block 4, and extends in the tire circumferential direction. .. Further, both ends of the uneven region A1 in the tire circumferential direction are terminated inside the tread surface of the block 4. Further, the smooth region A2 extends along the front and rear edge portions of the tread surface of the block 4 in the tire circumferential direction. As described above, the uneven region A1 does not have to cross the tread surface of the block 4 in the tire circumferential direction. Further, the adjacent smooth areas A2 and A2 may be continuous with each other.

On the other hand, in the configuration of FIG. 9, the smooth region A2 is shorter than the length Lb of the tread surface of the block 4, is arranged at the center of the tread surface of the block 4, and extends in the tire circumferential direction. Further, both ends of the smooth region A2 in the tire circumferential direction are terminated inside the tread surface of the block 4. Further, the uneven region A1 extends along the front and rear edge portions of the tread surface of the block 4 in the tire circumferential direction. As described above, the smooth region A2 does not have to cross the tread surface of the block 4 in the tire circumferential direction. Further, the concavo-convex regions A1 and A1 that are adjacent to each other may be continuous with each other.

Further, in the configuration of FIG. 10, the uneven region A1 is shorter than the length Lb of the tread surface of the block 4, and is arranged unevenly on the tread surface of the block 4 in the tire circumferential direction. Further, one end of the uneven region A1 in the tire circumferential direction is terminated at one edge of the tread of the block 4 in the tire circumferential direction, and the other end is terminated inside the tread of the block 4. Further, the smooth region A2 extends along the other edge portion of the tread surface of the block 4 in the tire circumferential direction.

Further, in the configuration of FIG. 11, in the configuration of FIG. 3, the uneven region A1 is divided in the tire circumferential direction at the central portion of the tread surface of the block 4. In other words, a pair of short and concavo-convex regions A1 and A1 are arranged so as to face each other and are separated from each other in the tire circumferential direction. Further, one uneven region A1 extends from the inside of the tread surface of the block 4 to one edge portion in the tire circumferential direction, and the other uneven region A1 extends from the inside of the tread surface of the block 4 to the other edge in the tire circumferential direction. It extends to the department. Further, a plurality of sets of uneven regions A1 and A1 are arranged at predetermined intervals in the tire width direction. Further, the adjacent smooth areas A2 and A2 are continuous with each other at the central portion of the block 4.

Further, in the configuration of FIG. 12, short and plurality of uneven regions A1 are arranged in a staggered pattern in the tire width direction. Further, one end of the uneven region A1 in the tire circumferential direction is terminated at one edge of the tread of the block 4 in the tire circumferential direction, and the other end is terminated inside the tread of the block 4. There is. Similarly, a plurality of short and smooth smooth regions A2 are arranged in a staggered pattern in the tire width direction. Further, one end of the smooth region A2 in the tire circumferential direction is terminated at one edge of the tread of the block 4 in the tire circumferential direction, and the other end is terminated inside the tread of the block 4. There is. Further, in the configuration of FIG. 12, adjacent uneven regions A1 and A1 are arranged in a staggered pattern in the tire circumferential direction with the corners abutting each other without wrapping each other in the tire circumferential direction and the tire width direction. There is. However, the present invention is not limited to this, and adjacent uneven regions A1 and A1 may be arranged in a staggered pattern while wrapping each other in the tire circumferential direction or the tire width direction, or may be separated from each other in the tire circumferential direction or the tire width direction. They may be arranged in a staggered pattern (not shown).

Further, in the configuration of FIG. 13, short and plurality of uneven regions A1 are arranged in a check pattern. Further, a part of the uneven region A1 extends to the edge portion of the tread surface of the block 4 in the tire circumferential direction. Similarly, a short and plurality of smooth areas A2 are arranged in a check pattern. Further, a part of the smoothing region A2 extends to the edge portion of the tread surface of the block 4 in the tire circumferential direction. Further, the smoothing region A2 is arranged at the edge portion of the tread surface of the block 4 in the tire width direction. In the configuration of FIG. 13, the number of check-shaped arrays composed of the uneven region A1 and the smooth region A2 is composed of 4 rows in the tire circumferential direction and 6 rows in the tire width direction, but the present invention is not limited to this. There may be 3 rows or 5 rows or more in the tire circumferential direction, or 3 rows to 5 rows or 7 rows or more in the tire width direction. As described above, the number of check-shaped sequences is not particularly limited, but is restricted by other conditions.

Further, in the configuration of FIG. 8, a plurality of concavo-convex regions A1 that are short and have the same circumferential length are aligned in the tire circumferential direction and arranged in parallel in the tire width direction. Similarly, in the configuration of FIG. 9, a plurality of smooth regions A2 that are short and have the same circumferential length are arranged in parallel in the tire width direction with the positions in the tire circumferential direction aligned.

However, the present invention is not limited to this, and as shown in FIG. 14, even if a plurality of concavo-convex regions A1 that are short and have the same circumferential length are arranged in parallel in the tire width direction while offsetting their positions in the tire circumferential direction. good. Similarly, as shown in FIG. 15, a plurality of smooth regions A2 that are short and have the same circumferential length may be arranged in parallel in the tire width direction while offsetting their positions in the tire circumferential direction.

Further, in the configurations of FIGS. 3 and 8, a plurality of uneven regions A1 having the same circumferential length are arranged in parallel in the tire width direction. Similarly, in the configurations of FIGS. 3 and 9, a plurality of smoothing regions A2 having the same circumferential length are arranged in parallel in the tire width direction.

However, the present invention is not limited to this, and as shown in FIG. 16, a plurality of uneven regions A1a and A1b having different circumferential lengths may be arranged in parallel in the tire width direction. For example, in the configuration of FIG. 16, a short uneven region A1a is arranged in the central region of the block 4 in the tire width direction, and a long uneven region A1b is arranged in the end region of the block 4 in the tire width direction. ing. Further, not limited to this, a long uneven region A1b is arranged in the central region of the block 4 in the tire width direction, and a short uneven region A1a is arranged in the end region of the block 4 in the tire width direction. Also good (not shown). Further, three or more uneven regions A1 are arranged on the tread surface of the block 4, and the circumferential length of these uneven regions A1 gradually decreases or gradually increases from one direction in the tire width direction of the block 4 toward the other. Also good (not shown).

Similarly, as shown in FIG. 17, a plurality of smoothing regions A2a and A2b having different circumferential lengths may be arranged in parallel in the tire width direction. For example, in the configuration of FIG. 17, a short smoothing region A2a is arranged in the central region of the block 4 in the tire width direction, and a long smoothing region A2b is arranged in the end region of the block 4 in the tire width direction. ing. Further, not limited to this, a long smoothing region A2b is arranged in the central region of the block 4 in the tire width direction, and a short smoothing region A2a is arranged in the end region of the block 4 in the tire width direction. Also good (not shown). Further, three or more uneven regions A1 are arranged on the tread surface of the block 4, and the circumferential length of these smooth regions A2 gradually decreases or gradually increases from one direction in the tire width direction of the block 4 toward the other. Also good (not shown).

Further, in the configuration of FIG. 3, a plurality of uneven regions A1 having the same width W1 are arranged in parallel in the tire width direction. Further, smooth regions A2 having the same width W2 are arranged between adjacent uneven regions A1 and A1.

However, the present invention is not limited to this, and as shown in FIGS. 18 and 19, a plurality of uneven regions A1 having different widths W1 may be arranged in parallel in the tire width direction. Further, the smoothing regions A2 having different widths W2 may be arranged between the adjacent uneven regions A1 and A1.

For example, in the configuration of FIG. 18, a concavo-convex region A1a having a narrow width W1a is arranged in the central region of the block 4 in the tire width direction, and a concavo-convex region having a wide width W1b is arranged in the end region of the block 4 in the tire width direction. Area A1b is arranged. Focusing on the smoothing regions A2a and A2b arranged between the adjacent uneven regions A1a and A1a; A1a and A1b, the smoothing region A2a having a narrow width W2a is arranged in the central region of the block 4 in the tire width direction. A smooth region A2b having a wide width W2b is arranged in the end region of the block 4 in the tire width direction. However, not limited to this, a wide concavo-convex region A1 is arranged in the central region of the block 4 in the tire width direction, and a narrow concavo-convex region A1 is arranged in the end region of the block 4 in the tire width direction. Also good (not shown). Further, regarding the smoothing region A2 arranged between the adjacent uneven regions A1 and A1, a wide smoothing region A2 is arranged in the central region of the block 4 in the tire width direction, and the end portion of the block 4 in the tire width direction. A narrow smooth region A2 may be arranged in the region (not shown).

Further, as shown in FIG. 19, three or more uneven regions A1a to A1d are arranged on the tread surface of the block 4, and the widths W1a to W1d of these uneven regions A1a to A1d are unidirectional in the tire width direction of the block 4. It may gradually decrease or gradually increase in the other direction. Further, three or more smoothing regions A2a to A2c are arranged between adjacent uneven regions A1a to A1d, and the widths W2a to W2c of these smoothing regions A2a to A2c are from one direction in the tire width direction of the block 4. It may gradually decrease or gradually increase in the other direction.

Further, in the configuration of FIG. 3, as described above, the smoothing region A2 is arranged at the left and right edge portions of the tread surface of the block 4 in the tire width direction.

However, the present invention is not limited to this, and as shown in FIG. 20, the uneven region A1 may be arranged at the left and right edge portions of the tread surface of the block 4 in the tire width direction. Further, the uneven region A1 may be arranged on one edge portion of the tread surface of the block 4 in the tire width direction, and the smooth region A2 may be arranged on the other edge portion (not shown).

Further, in the configuration of FIG. 3, four uneven regions A1 sandwiching the smooth region A2 are alternately arranged over the entire area of the tread surface of the block 4 in the tire width direction.

However, the present invention is not limited to this, and as shown in FIGS. 21 to 23, at least a pair of uneven regions A1 and A1 sandwiching the smooth region A2 may be arranged on the tread surface of the block 4. At this time, as shown in FIG. 21, the pair of uneven regions A1 may be unevenly arranged in one region of the tread surface of the block 4 in the tire width direction. Further, as shown in FIG. 22, a pair of wide uneven regions A1 may be arranged in a central region of the tread surface of the block 4 in the tire width direction. Further, as shown in FIG. 23, a pair of wide concavo-convex regions A1 and A1 are arranged at the left and right edge portions of the tread surface of the block 4 in the tire width direction, and a single smoothing region A2 is a single concavo-convex region A1. It may be arranged between A1.

Further, in the configuration of FIG. 3, as described above, the block 4 has a plurality of sipes 5, and these sipes 5 and the uneven region A1 and the smooth region A2 intersect with each other. However, the present invention is not limited to this, and the sipe 5 of the block 4 may be omitted (not shown). Further, the block 4 may have a narrow groove, a notch, and a chamfer on the tread surface instead of the sipe 5 or together with the sipe 5 (not shown).

24 to 35 are enlarged views showing a modified example of the arrangement structure of the uneven portion described in FIG. In these figures, the same components as those shown in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted.

In the configuration of FIG. 4, as described above, the boundary line between the concave-convex region A1 and the smooth region A2 is a straight line, and the concave-convex region A1 and the smooth region A2 have a rectangular shape as a whole (see FIG. 3).

However, the present invention is not limited to this, and the uneven region A1 and the smooth region A2 may have an arbitrary shape. That is, as described above, as the boundary line of the concavo-convex region A1, a group of concavo-convex portions 6 having a predetermined concavo-convex amount Hc and width Wc and densely arranged at a predetermined arrangement interval Dc are selected, and a group of these concavo-convex portions 6. The outermost end and edge of the uneven portion 6 of the above are connected by straight line segments, and the set of these line segments is approximated by a smooth straight line or curve and drawn. Therefore, in a configuration in which a group of uneven portions 6 are arranged so that their end positions are displaced from each other, the boundary line of the concave-convex region A1 may have a bent shape or a curved shape.

For example, as shown in FIG. 24, the uneven region A1 and the smooth region A2 may have a zigzag shape having an amplitude in the tire width direction, or may have a wavy shape (not shown). Further, as shown in FIG. 25, the uneven region A1 and the smooth region A2 may have an arc shape curved in the tire width direction, or may have a bent shape (not shown).

Further, in the configuration of FIG. 4, the uneven region A1 and the smooth region A2 have a long strip-like structure in the tire circumferential direction and extend parallel to the tire circumferential direction (θ = 0) (FIG. 3). reference). Further, the uneven region A1 and the smooth region A2 have constant widths W1 and W2.

However, the present invention is not limited to this, and as shown in FIG. 26, the longitudinal direction of the uneven region A1 and the smooth region A2 may be inclined with respect to the tire circumferential direction. However, as described above, it is preferable that the angle θ formed by the center line in the longitudinal direction of the uneven region A1 and the tire circumferential direction is in the range of −15 [deg] ≦ θ ≦ 15 [deg].

Further, as shown in FIG. 27, the widths W1 and W2 of the uneven region A1 and the smooth region A2 may change toward the tire circumferential direction. For example, in the configuration of FIG. 27, the width W1 of the uneven region A1 is monotonically decreasing and the width W2 of the smooth region A2 is monotonically increasing toward one side in the tire circumferential direction. However, the present invention is not limited to this, and the width W1 of the uneven region A1 may increase from the central portion in the longitudinal direction of the concave-convex region A1 toward both ends, or may decrease conversely (not shown). Further, the widths W1 and W2 of the uneven region A1 and the smooth region A2 may be periodically increased or decreased in the longitudinal direction of the uneven region A1 and the smooth region A2 (not shown).

Further, in the configuration of FIG. 4, adjacent uneven regions A1 and A1 are separated from each other. Therefore, the boundaries of each region are independent without intersecting each other.

However, the present invention is not limited to this, and as shown in FIGS. 28 and 29, adjacent uneven regions A1 and A1 may be continuous with each other. In other words, the smooth region A2 may be arranged between one continuous uneven region A1.

For example, in the configuration of FIG. 28, a part of the concavo-convex portion 6 is extended to form a connecting portion (reference numeral omitted in the drawing), and adjacent concavo-convex regions A1 and A1 are central portions in the longitudinal direction via the connecting portion. It is connected with. Further, since the plurality of uneven portions 6 are densely arranged at the connecting portion at a predetermined arrangement interval Dc, the connecting portion itself functions as the uneven region A1. Therefore, the adjacent uneven regions A1 and A1 have an H shape as a whole. As described above, the widths W1 and W2 of the uneven region A1 and the smooth region A2 are defined by an arbitrary cross section X in a predetermined circumferential range. Therefore, at the connecting portion of the concavo-convex regions A1 and A1 adjacent to each other, the width W1 of the concavo-convex region A1 increases, and the width W2 of the smooth region A2 becomes zero.

On the other hand, in the configuration of FIG. 29, the concavo-convex regions A1 and A1 are partially connected by a single concavo-convex portion 6 at a plurality of locations. Since the concavo-convex portion 6 of such a single unit does not sufficiently function as the concavo-convex region A1, it is defined as an intermediate region A3 that does not correspond to any of the concavo-convex region A1 and the smooth region A2.

Further, as shown in FIG. 30, when the tread surface of the block 4 is provided with another uneven portion 7 (for example, a deep groove, a notch, a sipe, etc.) that does not satisfy the condition of the uneven portion 6 constituting the uneven region A1. Is defined as a concavo-convex region A1 and a smoothed region A2 excluding the other concavo-convex portion 7. For example, in the configuration of FIG. 30, another concavo-convex portion 7 penetrates the first concavo-convex region A1 and the smooth region A2, intersects the second concavo-convex region A1, and terminates. In this case, the intermediate region A3 is defined by the boundary line along the outer edge of the other uneven portion 7. This intermediate region A3 does not correspond to any of the uneven region A1 and the smooth region A2. For example, in the configuration of FIG. 30, the first uneven region A1 and the smooth region A2 are divided by the intermediate region A3, and a part of the second uneven region A1 is eroded by the intermediate region A3.

Further, in the configuration of FIG. 4, as described above, the longitudinal direction of the group of uneven portions 6 constituting the uneven region A1 is inclined at a predetermined inclination angle (dimension symbols omitted in the figure) with respect to the tire circumferential direction. ing. Further, each uneven portion 6 is continuous in the uneven region A1. Further, in the configuration of FIG. 4, the uneven portion 6 is a fine shallow groove.

However, the present invention is not limited to this, and as shown in FIG. 31, a group of uneven portions 6 constituting the uneven region A1 may extend substantially parallel to the tire circumferential direction. Specifically, it is preferable that the angle formed by the longitudinal direction of the uneven portion 6 and the tire circumferential direction is in the range of 0 [deg] or more and less than 20 [deg]. For example, in the configuration of FIG. 31, all the uneven portions 6 extend parallel to the tire circumferential direction. In such a configuration, a group of concavo-convex portions 6 densely arranged at a predetermined narrow disposition interval Dc is selected, and the boundary line of the concavo-convex region A1 is on the outer edge of the outermost concavo-convex portion 6 among these concavo-convex portions 6. It is drawn along. Further, the region between the adjacent uneven portions 6 and 6 arranged at a wide arrangement interval Dc is defined as the smooth region A2 on the condition that the region has a predetermined flat tread surface.

Further, as shown in FIG. 32, a group of uneven portions 6 constituting the uneven region A1 may extend substantially perpendicular to the tire circumferential direction. Specifically, it is preferable that the angle formed by the longitudinal direction of the uneven portion 6 and the tire peripheral direction is in the range of more than 70 [deg] and 90 [deg] or less. For example, in the configuration of FIG. 32, all the uneven portions 6 extend perpendicular to the tire circumferential direction.

Further, as shown in FIG. 33, the uneven portion 6 may be divided in the uneven region A1. For example, in the configuration of FIG. 33, the concavo-convex portion 6 in the concavo-convex region A1 is a short narrow shallow groove, and has at least one end in the concavo-convex region A1 without crossing the concavo-convex region A1. ..

Further, as shown in FIG. 34, the uneven portion 6 may be dimples. For example, in the configuration of FIG. 34, the uneven portion 6 is a spherical or cylindrical dimple having a shallow depth (concavo-convex amount Hc. See FIG. 6) and a small outer diameter (width Wc). Further, a group of uneven portions 6 are densely arranged at a predetermined arrangement interval Dc, and are arranged in a staggered pattern in the tire circumferential direction and the tire width direction. Then, a band-shaped uneven region A1 is formed by these uneven portions 6. Further, the smooth region A2 is formed between the adjacent uneven regions A1 and A1.

Further, as shown in FIG. 35, in the configuration of FIG. 34, the concavo-convex portion 6 isolated from the group of concavo-convex portions 6 constituting the concavo-convex region A1 may be arranged in the smooth region A2. That is, when the arrangement interval Dc between the isolated concavo-convex portion 6 and the group of concavo-convex portions 6 is large, the isolated concavo-convex portion 6 is not included in either the concavo-convex region A1 or the smooth region A2, and constitutes the intermediate region A3. do. When a plurality of uneven portions 6 in the smooth region A2 are densely arranged with a narrow arrangement interval Dc (not shown), these uneven portions 6 form one uneven region A1.

36 to 39 are explanatory views showing a modified example of the uneven portion shown in FIGS. 5 and 6.

In the configuration of FIG. 3, as shown in FIGS. 5 and 6, the uneven portion 6 is a shallow groove.

However, the present invention is not limited to this, and as shown in FIGS. 36 and 37, the uneven portion 6 may be a convex portion (for example, a fine rib or a small protrusion) having a predetermined uneven amount Hc and width Wc. Further, as shown in FIGS. 38 and 39, a group of uneven portions 6 may include both concave portions and convex portions. Even in such a case, the concavo-convex region A1 is formed by densely arranging the group of concavo-convex portions 6 at a predetermined arrangement interval Dc. In the configuration in which the concave portion 6a and the convex portion 6b are mixed as shown in FIG. 39, the width Wc (Wc_a, Wc_b) and the unevenness amount Hc (Hc_a, Hc_b) are flat on the tread surface of the block 4 as described above. It is measured with reference to a certain area.

FIG. 40 is a plan view showing a modified example of the tread surface shown in FIG. The figure shows the tread surface of a winter studless tire. 41 to 43 are plan views showing the treads of the blocks shown in FIG. 40. These figures show a single block 4 partitioned by grooves 2c and 2d (see FIG. 40). Further, in these figures, the same components as those shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.

In the configuration of FIG. 2, the groove 2a is a circumferential main groove and extends continuously over the entire circumference of the tire. Further, the groove 2b is a through lug groove, which penetrates the tread surface in the tire width direction and opens to the left and right tire contact ends T. Further, the plurality of grooves 2a and 2b have a predetermined groove width and groove depth, are arranged in a grid pattern, and communicate with each other. As a result, five block rows are divided in the tire width direction.

On the other hand, in the configuration of FIG. 40, the groove 2c is an inclined lug groove inclined with respect to the tire circumferential direction, and the inclination angle with respect to the tire circumferential direction is stepped from the vicinity of the tire equatorial plane CL toward the tire ground contact end T. It is increasing and extending. Further, the groove 2c is the main groove and is obliged to display the slip sign specified in JATTA. Further, a plurality of grooves 2c communicate with each other in a V shape to form a directional tread pattern. Further, the groove 2d is a circumferential groove extending in the tire circumferential direction, and is arranged in the shoulder region of the tread portion to connect adjacent grooves 2c and 2c. Since these grooves 2c and 2c have a predetermined groove width and groove depth, a plurality of types of blocks 4A, 4B, and 4C are partitioned.

In the configuration of FIG. 41, the block 4A is located on the tire ground contact end T and is divided into a pair of inclined lug grooves 2c and 2c and a circumferential groove 2d (see FIG. 40). Further, the block 4A has a rectangular shape or a trapezoidal shape that is slightly distorted as a whole. Further, the tread surface of the block 4A, that is, the ground contact area is partitioned by the tire ground contact end T, and a plurality of uneven portions 6 are formed on the tread surface of the block 4A. Further, a group of concavo-convex portions 6 are densely arranged at a predetermined arrangement interval Dc (see FIG. 4) to form a long strip-shaped concavo-convex region A1 in the tire circumferential direction. Further, a plurality of uneven regions A1 are arranged in parallel in the tire width direction. Further, the smooth region A2 is arranged between the adjacent uneven regions A1 and A1. Further, a plurality of sipes 5 extend in the tire width direction and intersect the uneven region A1 and the smooth region A2. In the configuration of FIG. 41, the uneven region A1 is formed only in the region inside the tire ground contact end T, but the present invention is not limited to this, and the uneven region A1 is a region outside the tire ground contact end T, that is, It may be formed in a non-grounded region (not shown).

In the configuration of FIG. 42, the block 4B is located in the center region of the tread portion and is divided into a pair of inclined lug grooves 2c and 2c and a circumferential groove 2d (see FIG. 40). Further, the block 4B has a long substantially parallel quadrilateral shape, and its longitudinal direction is inclined with respect to the tire circumferential direction. Further, a plurality of uneven portions 6 are formed on the tread surface of the block 4B. Further, a group of concavo-convex portions 6 are densely arranged at a predetermined arrangement interval Dc (see FIG. 4) to form a long strip-shaped concavo-convex region A1 in the tire circumferential direction. Further, a plurality of uneven regions A1 are arranged in parallel along the longitudinal direction of the block 4B. Further, the smooth region A2 is arranged between the adjacent uneven regions A1 and A1. Further, a plurality of sipes 5 extend in the tire width direction and intersect the uneven region A1 and the smooth region A2. The block 4B includes a narrow groove 7a and a notch 7b deeper than the uneven portion 6. Further, these narrow grooves 7a and the cutout portion 7b intersect the uneven region A1 and the smooth region A2.

In the configuration of FIG. 43, the block 4C is on the tire equatorial plane CL and is divided into a plurality of inclined lug grooves 2c and a circumferential groove 2d (see FIG. 40). Further, the block 4C has a substantially L-shape in which a long portion and a short portion are connected, and the long portion extends in the tire width direction while being inclined with respect to the tire circumferential direction, and the short portion thereof. It extends in the tire circumferential direction along the tire equatorial plane CL. Further, a plurality of uneven portions 6 are formed on the tread surface of the block 4C. Further, a group of concavo-convex portions 6 are densely arranged at a predetermined arrangement interval Dc (see FIG. 4) to form a long strip-shaped concavo-convex region A1 in the tire circumferential direction. Further, a plurality of uneven regions A1 are arranged in parallel along the longitudinal direction of the block 4C. Further, the smooth region A2 is arranged between the adjacent uneven regions A1 and A1. Further, a plurality of sipes 5 extend in the tire width direction and intersect the uneven region A1 and the smooth region A2. The block 4C includes a narrow groove 7a and a notch 7b deeper than the uneven portion 6. Further, these narrow grooves 7a and the cutout portion 7b intersect the uneven region A1 and the smooth region A2.

[effect]
As described above, the pneumatic tire 1 includes a plurality of blocks 4 on the tread surface (see FIG. 2). Further, the block 4 is provided with a plurality of uneven portions 6 on the tread surface (see FIG. 3). Further, the unevenness amount Hc (see FIG. 6) of the uneven portion 6 is in the range of 0.1 [mm] ≦ Hc ≦ 1.0 [mm]. Further, the width Wc of the uneven portion 6 (see FIG. 4) is in the range of 0.1 [mm] ≦ Wc ≦ 0.8 [mm]. A region in which the arrangement interval Dc of the adjacent uneven portions 6 is in the range of Dc ≦ 1.2 [mm] is defined as the concave-convex region A1, and is a region other than the concave-convex region A1 and is the arithmetic mean coarseness of the tread surface of the block 4. The region where Ra is in the range of Ra ≦ 50 [μm] is defined as the smooth region A2, the cross section X perpendicular to the tire circumferential direction is defined, and the circumferential length of the tread of the block 4 in the tire circumferential direction. Define Lb. At this time, the block 4 has a concavo-convex region A1 and a smooth region A2, respectively, in an arbitrary cross-sectional X in a circumferential range of 40 [%] or more of the circumferential length Lb of the tread of the block 4 (FIGS. 3 and 3). 4).

In such a configuration, (1) since the uneven region A1 composed of the fine uneven portions 6 in which the treads of the block 4 are densely arranged is provided, the uneven region A1 absorbs and removes the water film on the icy road surface. Further, since the tread surface of the block 4 includes the flat smoothing region A2, the contact area of the block 4 with respect to the icy road surface is secured. Since the uneven region A1 and the smooth region A2 are arranged in a mixed manner, the adhesive frictional force of the smooth region A2 with respect to the icy road surface is improved. This has the advantage that the ground contact characteristics of the block 4 with respect to the icy road surface are improved, and the performance on ice of the tire is synergistically improved.

In particular, (2) when the vehicle turns, the tread surface of the block 4 slides in the tire width direction and touches the icy road surface. At this time, since the uneven region A1 and the smooth region A2 are arranged in a mixed manner in the tire width direction (that is, on the cross section X perpendicular to the tire circumferential direction), the synergistic action of the uneven region A1 and the smooth region A2 causes the uneven region A1 and the smooth region A2 to act synergistically. The grounding characteristics of the block 4 are improved. This has the advantage that the turning performance on ice of the tire is efficiently improved.

Further, (3) the uneven amount Hc, the width Wc, and the arrangement interval Dc of the uneven portion 6 constituting the uneven region A1 are within the above numerical ranges, so that there is an advantage that the water film absorbing action of the uneven region A1 is properly secured. be. If these numerical values are too large or too small, the water film absorbing action of the uneven region A1 is reduced.

Further, (4) Since the lower limits of the widths W1 and W2 of the uneven region A1 and the smooth region A2 are within the above ranges, there is an advantage that the above-mentioned actions of the uneven region A1 and the smooth region A2 are properly ensured.

Further, in the pneumatic tire 1, the smooth region A2 is arranged between the adjacent uneven regions A1 and A1 (see FIG. 3). In such a configuration, the adjacent uneven regions A1 and A1 absorb the water film on the icy road surface on both sides of the smooth region A2. This has the advantage that the adhesive frictional force of the smooth region A2 with respect to the icy road surface is improved, and the performance of the tire on ice is further improved.

Further, in the pneumatic tire 1, the smooth region A2 is arranged between the three or more uneven regions A1 (see FIG. 3). That is, in a predetermined circumferential range, three or more uneven regions A1 are arranged in a striped pattern with a smooth region A2 sandwiched between them. This has the advantage that the adhesive frictional force of the smooth region A2 with respect to the icy road surface is further improved.

Further, in the pneumatic tire 1, the width W1 of the uneven region A1 is in the range of 1.0 [mm] ≦ W1, and the width W2 of the smooth region A2 is in the range of 2.0 [mm] ≦ W2 (FIG. 3). As a result, there is an advantage that the widths W1 and W2 of the uneven region A1 and the smooth region A2 are secured, respectively, and the functions of the uneven region A1 and the smooth region A2 are secured.

Further, in the pneumatic tire 1, the width W1 of the uneven region A1 and the width W2 of the smooth region A2 adjacent to the uneven region A1 have a relationship of 0.50 ≦ W1 / W2 ≦ 1.50 (FIG. 3). In such a configuration, since the widths W1 and W2 of the concavo-convex region A1 and the smoothing region A2 that are adjacent to each other are set to be substantially the same, there is an advantage that the effect of the mixed arrangement of the concavo-convex region A1 and the smoothing region A2 can be effectively obtained. be.

Further, in the pneumatic tire 1, the total sum ΣW1 of the width W1 of the uneven region A1 and the length Wb'of the tread surface of the block 4 in the cross section X have a relationship of 0.20 ≦ ΣW1 / Wb'(FIG. 3). reference). As a result, there is an advantage that the total width ΣW1 of the uneven region A1 in a predetermined circumferential direction range is appropriately secured.

Further, in the pneumatic tire 1, the total sum ΣW2 of the width W2 of the smooth region A2 and the length Wb'of the tread surface of the block 4 in the cross section X have a relationship of 0.20 ≦ ΣW2 / Wb'(FIG. 3). reference). As a result, there is an advantage that the total width ΣW2 of the smoothing region A2 in a predetermined circumferential direction range is appropriately secured.

Further, in the pneumatic tire 1, the area ratio of the uneven portion 6 in the uneven region A1 is within the range of 20 [%] or more and 45 [%] or less. This has the advantage that the water film removing action of the uneven portion 6 in the uneven region A1 is more appropriately ensured.

Further, in the pneumatic tire 1, the width Wc and the arrangement interval Dc of the uneven portion 6 in the uneven region A1 have a relationship of 0.80 ≦ Dc / Wc (see FIG. 4). As a result, there is an advantage that the ground contact area inside the uneven region A1 is secured and the ground contact characteristic of the concave-convex region A1 itself is improved.

Further, in the pneumatic tire 1, the arrangement interval Dc of the uneven portion 6 in the uneven region A1 and the width W2 of the smooth region A2 have a relationship of 4.0 ≦ W2 / Dc (see FIG. 4). This has the advantage that the effect of the mixed arrangement of the uneven region A1 and the smooth region A2 can be appropriately obtained.

Further, in the pneumatic tire 1, the uneven region A1 has a long shape in the tire circumferential direction, and the angle θ formed by the center line in the longitudinal direction of the concave-convex region A1 and the tire circumferential direction is −15. It is in the range of [deg] ≤ θ ≤ 15 [deg] (see FIG. 3). As a result, there is an advantage that the angle θ in the longitudinal direction of the uneven region A1 is optimized and the function of the uneven region A1 is properly secured.

Further, in the pneumatic tire 1, the smooth region A2 extends along the edge portion of the tread surface of the block 4 in the tire width direction (see FIG. 3). This has the advantage that the ground contact area of the block 4 is increased, and the tire turning performance on ice and skidding resistance are improved.

Further, in the pneumatic tire 1, the uneven region A1 extends along the edge portion of the tread surface of the block 4 in the tire width direction (see FIG. 20). As a result, the water removal of the tread surface of the block 4 is improved, and there is an advantage that the turning performance on ice and the skidding resistance of the tire are improved.

Further, in the pneumatic tire 1, the uneven portion 6 is a fine shallow groove (see FIGS. 4 to 7). In such a configuration, since the uneven portion 6 has a long structure, there is an advantage that the water removing action of the uneven portion 6 can be efficiently obtained as compared with the configuration in which the uneven portion 6 is a short dimple (see FIG. 34). be.

FIG. 44 is a chart showing the results of a performance test of a pneumatic tire according to an embodiment of the present invention.

In this performance test, multiple types of test tires were evaluated for their turning performance on ice. Further, a test tire having a tire size of 195 / 65R15 91Q is assembled to a rim having a rim size of 15 × 6J, and an internal pressure of 210 [kPa] and a specified load of JATTA are applied to the test tire. Further, the test tire is mounted on a sedan having a displacement of 1600 [cc] and an FF (Front engine Front drive) system, which is a test vehicle.

In the evaluation of the turning performance on ice, the test vehicle turns on the ice road surface along a circle with a radius of 30 [m], the lap time is measured, and the feeling of the test driver is evaluated. Then, based on these, an index evaluation based on the conventional example (100) is performed. The larger the numerical value, the more preferable this evaluation.

The test tires of Examples 1 to 9 have the structures shown in FIGS. 1 to 7. Further, the circumferential length Lb of the block 4 is Lb = 50 [mm], and the width direction length Wb is Wb = 40 [mm]. Further, the block 4 has a sipe 5, the depth of the sipe 5 is 7.0 [mm], and the width is 0.8 [mm]. Further, the tread surface of the block 4 includes a concave-convex region A1 and a smooth region A2, and the concave-convex portion 6 of the concave-convex region A1 is composed of a shallow groove. Further, a plurality of sets of uneven regions A1 and smooth regions A2 having predetermined widths W1 and W2 are arranged in parallel in the tire width direction. Further, the surface processed portions other than the uneven portion 6 and the sipe 5 described above are not applied to the tread surface of the block 4, and the block 4 has a plain tread surface.

In the test tire of the conventional example, in the test tire of the first embodiment, the uneven portions 6 are arranged over the entire tread surface of the block 4.

As the test results show, it can be seen that the test tires of Examples 1 to 9 improve the turning performance on ice of the tire.

1: Pneumatic tires, 2a to 2d: Grooves, 4, 4A to 4C: Blocks, 5: Sipe, 6: Concavo-convex parts, 7: Other uneven parts, 11: Bead core, 12: Bead filler, 13: Carcus layer, 14: Belt layer, 141, 142: Cross belt, 143: Belt cover, 15: Tread rubber, 16: Sidewall rubber, 17: Rim cushion rubber, A1: Concavo-convex area, A2: Smooth area, A3: Intermediate area

Claims (19)

Pneumatic tires with multiple blocks on the tread surface
The block is provided with a plurality of uneven portions on the tread surface.
The unevenness amount Hc of the uneven portion is in the range of 0.1 [mm] ≤ Hc ≤ 1.0 [mm].
The width Wc of the uneven portion is in the range of 0.1 [mm] ≤ Wc ≤ 0.8 [mm].
A region in which the arrangement interval Dc of the adjacent uneven portions is in the range of Dc ≦ 1.2 [mm] is defined as an uneven region.
A region other than the uneven region, in which the arithmetic mean roughness Ra of the tread surface of the block is in the range of Ra ≦ 50 [μm], is defined as a smooth region.
Define a cross section X perpendicular to the tire circumferential direction,
The circumferential length Lb of the tread surface of the block in the tire circumferential direction is defined .
The block, in any cross-section X in the circumferential range 40% or more of the circumferential length Lb of the tread of the block, two or more of the irregular region and two or more of the smooth region possess respectively, and,
A pneumatic tire , wherein one uneven region in a cross section X is composed of a plurality of the uneven portions. The pneumatic tire according to claim 1, wherein the smooth region is arranged between adjacent uneven regions. The pneumatic tire according to claim 1 or 2, wherein the smooth region is arranged between three or more uneven regions, respectively. One of claims 1 to 3 in which the width W1 of the uneven region is in the range of 1.0 [mm] ≦ W1 and the width W2 of the smooth region is in the range of 2.0 [mm] ≦ W2. Pneumatic tires listed. The one according to any one of claims 1 to 4, wherein the width W1 of the uneven region and the width W2 of the smooth region adjacent to the uneven region have a relationship of 0.50 ≦ W1 / W2 ≦ 1.50. Pneumatic tires. 6. Pneumatic tires. 6. Pneumatic tires. The pneumatic tire according to any one of claims 1 to 7, wherein the area ratio of the uneven portion in the uneven region is in the range of 20 [%] or more and 45 [%] or less. The pneumatic tire according to any one of claims 1 to 8, wherein the width Wc of the uneven portion and the arrangement interval Dc in the uneven region have a relationship of 0.80 ≦ Dc / Wc. The pneumatic tire according to any one of claims 1 to 9, wherein the arrangement interval Dc of the uneven portion in the uneven region and the width W2 of the smooth region have a relationship of 4.0 ≦ W2 / Dc. The uneven region has a long shape in the tire circumferential direction, and the angle θ formed by the center line in the longitudinal direction of the uneven region and the tire circumferential direction is −15 [deg] ≤ θ ≤ 15 [deg]. ], The pneumatic tire according to any one of claims 1 to 10. The pneumatic tire according to any one of claims 1 to 11, wherein the smooth region extends along an edge portion of the tread surface of the block in the tire width direction. The pneumatic tire according to any one of claims 1 to 11, wherein the uneven region extends along an edge portion of the tread surface of the block in the tire width direction. The pneumatic tire according to any one of claims 1 to 13, wherein the uneven portion is a fine shallow groove. The uneven region and the smooth region have a long strip-like structure in the tire circumferential direction, and the tread of the block continuously extends from one end to the other end of the tread in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 14, which crosses the tread surface in the tire circumferential direction. The uneven region is arranged at the center of the tread surface of the block, extends in the tire circumferential direction, terminates inside the tread surface of the block, and
The pneumatic tire according to any one of claims 1 to 15, wherein the smooth region extends along the front and rear edge portions of the tread surface of the block in the tire circumferential direction. Pneumatic tires with multiple blocks on the tread surface
The block is provided with a plurality of uneven portions on the tread surface.
The unevenness amount Hc of the uneven portion is in the range of 0.1 [mm] ≤ Hc ≤ 1.0 [mm].
The width Wc of the uneven portion is in the range of 0.1 [mm] ≤ Wc ≤ 0.8 [mm].
A region in which the arrangement interval Dc of the adjacent uneven portions is in the range of Dc ≦ 1.2 [mm] is defined as an uneven region.
A region other than the uneven region, in which the arithmetic mean roughness Ra of the tread surface of the block is in the range of Ra ≦ 50 [μm], is defined as a smooth region.
Define a cross section X perpendicular to the tire circumferential direction,
The circumferential length Lb of the tread surface of the block in the tire circumferential direction is defined .
The block, in any cross-section X in the circumferential range 40% or more of the circumferential length Lb of tread of said block, said irregular region and the smooth region possess respectively, and,
A pneumatic tire characterized in that the uneven portion has a non-annular and long structure. The 17th aspect of claim 17, wherein the uneven portion is a fine shallow groove, and the longitudinal direction of the fine shallow groove is inclined at an inclination angle of 20 [deg] or more and 70 [deg] or less with respect to the tire circumferential direction. tire. Pneumatic tires with multiple blocks on the tread surface
The block is provided with a plurality of uneven portions on the tread surface.
The unevenness amount Hc of the uneven portion is in the range of 0.1 [mm] ≤ Hc ≤ 1.0 [mm].
The width Wc of the uneven portion is in the range of 0.1 [mm] ≤ Wc ≤ 0.8 [mm].
A region in which the arrangement interval Dc of the adjacent uneven portions is in the range of Dc ≦ 1.2 [mm] is defined as an uneven region.
A region other than the uneven region, in which the arithmetic mean roughness Ra of the tread surface of the block is in the range of Ra ≦ 50 [μm], is defined as a smooth region.
Define a cross section X perpendicular to the tire circumferential direction,
The circumferential length Lb of the tread surface of the block in the tire circumferential direction is defined .
The block, in any cross-section X in the circumferential range 40% or more of the circumferential length Lb of tread of said block, said irregular region and the smooth region possess respectively, and,
A pneumatic tire characterized in that the width W1 of the uneven region and the width W2 of the smooth region adjacent to the uneven region have a relationship of 0.50 ≦ W1 / W2 ≦ 1.50.

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