WO2016088853A1 - 空気入りタイヤ - Google Patents
空気入りタイヤ Download PDFInfo
- Publication number
- WO2016088853A1 WO2016088853A1 PCT/JP2015/084057 JP2015084057W WO2016088853A1 WO 2016088853 A1 WO2016088853 A1 WO 2016088853A1 JP 2015084057 W JP2015084057 W JP 2015084057W WO 2016088853 A1 WO2016088853 A1 WO 2016088853A1
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- WIPO (PCT)
- Prior art keywords
- tire
- region
- recess
- width direction
- opening area
- Prior art date
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
Definitions
- the present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve the performance of the tire on snow.
- the present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire that can improve the performance of the tire on snow.
- a pneumatic tire according to the present invention is a pneumatic tire provided with a land portion having ribs or a plurality of blocks on a tread surface, wherein the land portion includes a plurality of shallow grooves and a plurality of recesses.
- a region of the center 50 [%] in the tire width direction of the continuous contact surface in the land portion is defined as a center region, and the left and right end portions 25 [%] in the tire width direction Is defined as an end region, the opening area ratio Sc of the recess in the central region in the tire width direction of one of the continuous contact surfaces, and the recess in the end region in the tire width direction
- the opening area ratio Se has a relationship of Se ⁇ Sc.
- the pneumatic tire according to the present invention is a pneumatic tire provided with a land portion having a plurality of blocks on a tread surface, the land portion including a plurality of shallow grooves and a plurality of concave portions on a ground contact surface, Further, when the region of the central portion 50 [%] in the tire circumferential direction of the continuous contact surface is defined as the central region, and the region of the end portion 25 [%] in the tire circumferential direction is defined as the end region.
- An opening area ratio Sc ′ of the recess in the central region in the tire circumferential direction of one continuous ground contact surface and an opening area ratio Se ′ in the recess in the end region in the tire circumferential direction are Se ′. ⁇ Sc ′ relationship.
- the opening area ratio of the recess is set large in the center region in the tire width direction or the tire circumferential direction, the contact area in the center region decreases, the contact pressure increases, The snow column shearing force due to the recess increases.
- FIG. 1 is a 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 a tread surface of the pneumatic tire depicted in FIG. 1.
- FIG. 3 is an explanatory diagram illustrating a land portion of the pneumatic tire illustrated in FIG. 2.
- FIG. 4 is an enlarged view showing a main part of the block shown in FIG.
- FIG. 5 is a cross-sectional view taken along line AA of the ground contact surface of the block illustrated in FIG.
- FIG. 6 is an explanatory diagram showing a land portion of the pneumatic tire depicted in FIG. 2.
- FIG. 7 is an explanatory diagram illustrating a land portion of the pneumatic tire illustrated in FIG. 2.
- FIG. 8 is an explanatory view showing a modification of the pneumatic tire shown in FIG.
- FIG. 9 is an explanatory diagram showing a modified example of the pneumatic tire depicted in FIG. 4.
- FIG. 10 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 4.
- FIG. 11 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4.
- FIG. 12 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 4.
- FIG. 13 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4.
- FIG. 14 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4.
- FIG. 15 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 4.
- FIG. 16 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4.
- FIG. 17 is an explanatory diagram showing a modification of the pneumatic tire depicted in FIG.
- FIG. 18 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 4.
- FIG. 19 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4.
- FIG. 20 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 4.
- FIG. 21 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 4.
- FIG. 22 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 2.
- FIG. 23 is an explanatory diagram showing a modified example of the pneumatic tire depicted in FIG. 2.
- FIG. 24 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 2.
- FIG. 25 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 2.
- FIG. 26 is an explanatory diagram showing a land portion of the pneumatic tire depicted in FIG. 25.
- FIG. 27 is an explanatory diagram illustrating a land portion of the pneumatic tire illustrated in FIG. 25.
- FIG. 28 is an explanatory diagram showing a land portion of the pneumatic tire depicted in FIG. 25.
- FIG. 29 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 25.
- FIG. 30 is an explanatory diagram showing a modification of the pneumatic tire depicted in FIG.
- FIG. 31 is an explanatory diagram showing a modified example of the pneumatic tire depicted in FIG. 25.
- FIG. 32 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.
- FIG. 33 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.
- FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. This figure shows a cross-sectional view of one side region in the tire radial direction. The figure shows a radial tire for a passenger car as an example of a pneumatic tire.
- the cross section in the tire meridian direction means a cross section when the tire is cut along a plane including the tire rotation axis (not shown).
- Reference sign CL denotes a tire equator plane, which is 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
- the tire radial direction means a direction perpendicular to the tire rotation axis.
- the pneumatic tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. And 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 core of the left and right bead portions.
- the pair of bead fillers 12 and 12 are disposed on the outer circumference in the tire radial direction of the pair of bead cores 11 and 11 to constitute a bead portion.
- the carcass layer 13 has a single layer structure composed of a single carcass ply or a multilayer structure formed by laminating a plurality of carcass plies, and is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form a tire skeleton. Constitute. Further, both end portions 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 a coat rubber and rolling it, and has an absolute value of 80 It has a carcass angle (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction) of [deg] or more and 95 [deg] or less.
- an organic fiber material for example, aramid, nylon, polyester, rayon, etc.
- the belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, and is arranged around the outer periphery of the carcass layer 13.
- the pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and has an absolute value of a belt angle of 20 [deg] or more and 55 [deg] or less.
- the pair of cross belts 141 and 142 have belt angles with different signs from each other (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction), and are laminated so that the fiber directions of the belt cords cross each other. (Cross ply structure).
- the belt cover 143 is formed by rolling a plurality of cords made of steel or organic fiber material covered with a coat rubber, and has a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. Further, the belt cover 143 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 141 and 142.
- the tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire.
- the pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions.
- the pair of rim cushion rubbers 17, 17 are respectively disposed on the inner side in the tire radial direction of the wound portions of the left and right bead cores 11, 11 and the carcass layer 13, and constitute the contact surfaces of the left and right bead portions with respect to the rim flange.
- FIG. 2 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1.
- the figure shows a tread pattern of a studless tire.
- the tire circumferential direction refers to the direction around the tire rotation axis.
- Reference symbol T denotes a tire ground contact end.
- the pneumatic tire 1 includes a plurality of circumferential main grooves 21 and 22 extending in the tire circumferential direction, and a plurality of land portions 31 to 22 partitioned by the circumferential main grooves 21 and 22. 33 and a plurality of lug grooves 41 to 43 arranged in the land portions 31 to 33 are provided in the tread portion.
- the circumferential main groove is a circumferential groove having a wear indicator indicating the end of wear, and generally has a groove width of 5.0 [mm] or more and a groove depth of 7.5 [mm] or more.
- the lug groove means a lateral groove having 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 filled with the specified internal pressure.
- the groove width is based on the intersection of the tread surface and the extension line of the groove wall in a cross-sectional view in which the groove length direction is a normal direction. Measured.
- the groove width is measured with reference to the center line of the amplitude of the groove wall.
- the groove depth is measured as the maximum value of the distance from the tread surface to the groove bottom in an unloaded state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Moreover, in the structure which a groove
- Specified rim means “Applicable rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO.
- the specified internal pressure refers to the “maximum air pressure” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO.
- the specified load is the “maximum load capacity” specified in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified in TRA, or “LOAD CAPACITY” specified in ETRTO.
- the specified internal pressure is air pressure 180 [kPa]
- the specified load is 88 [%] of the maximum load capacity.
- the four circumferential main grooves 21 and 22 having a straight shape are arranged symmetrically about the tire equatorial plane CL.
- five rows of land portions 31 to 33 are defined by the four circumferential main grooves 21 and 22.
- the land portion 31 is disposed on the tire equator plane CL.
- the land portions 31 to 33 include a plurality of lug grooves 41 to 43 that are arranged at predetermined intervals in the tire circumferential direction and penetrate the land portions 31 to 33 in the tire width direction.
- the second land portion 32 includes a circumferential narrow groove 23 that extends while being bent in the tire circumferential direction.
- the land portions 31 to 33 are partitioned into circumferential main grooves 21 and 22, circumferential narrow grooves 23, and lug grooves 41 to 43 to form a block row.
- the circumferential main grooves 21 and 22 have a straight shape as described above.
- the present invention is not limited to this, and the circumferential main grooves 21 and 22 may have a zigzag shape or a wavy shape extending while being bent or curved in the tire circumferential direction (not shown).
- the land portions 31 to 33 are divided in the tire circumferential direction by the lug grooves 41 to 43 to form a block row.
- the present invention is not limited to this.
- the land portions 31 to 33 may be ribs continuous in the tire circumferential direction. Good (not shown).
- the pneumatic tire 1 has a tread pattern that is symmetrical with respect to the left and right.
- the present invention is not limited to this, and the pneumatic tire 1 may have, for example, a tread pattern that is symmetrical to the left and right lines, a tread pattern that is asymmetrical to the left and right, and a tread pattern that has directionality in the tire rotation direction (not shown).
- the pneumatic tire 1 includes circumferential main grooves 21 and 22 extending in the tire circumferential direction.
- the pneumatic tire 1 may include a plurality of inclined main grooves that extend while being inclined at a predetermined angle with respect to the tire circumferential direction, instead of the circumferential main grooves 21 and 22.
- the pneumatic tire 1 has a V-shape that is convex in the tire circumferential direction, and extends in the tire width direction and opens to the left and right tread ends, and adjacent V-shaped slopes. You may provide the several lug groove which connects a main groove, and the several land part divided by these V-shaped inclination main grooves and lug grooves (illustration omitted).
- FIG. 3 is an explanatory diagram illustrating a land portion of the pneumatic tire illustrated in FIG. 2. The figure shows a plan view of one block 5 constituting the shoulder land portion 33.
- the blocks 5 of all the land portions 31 to 33 have a plurality of sipes 6, respectively.
- sipes 6 the edge components of the land portions 31 to 33 are increased, and the performance of the tire on ice and snow is improved.
- a sipe is an incision formed in a land portion, and generally 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 at the time of tire contact.
- 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 ground contact surface in the land portion in a no-load state in which the tire is mounted on the specified rim and filled with the specified internal pressure.
- the sipe 6 has a closed structure that terminates in the land portions 31 to 33 at both ends, opens to the edge of the block 5 at one end, and terminates in the block 5 at the other end. It may have either a semi-closed structure or an open structure that opens to the edge portion of the block 5 at both ends. Further, the length, the number, and the arrangement structure of the sipes 6 in the land portions 31 to 33 can be appropriately selected within the range obvious to those skilled in the art. Further, the sipe 6 can extend in any direction of the tire width direction, the tire circumferential direction, and the direction inclined to these.
- the shoulder land portion 33 includes a plurality of blocks 5 that are partitioned into an outermost circumferential main groove 22 and a plurality of lug grooves 43 (see FIG. 2).
- One block 5 includes a plurality of sipes 6. These sipes 6 have a zigzag shape extending in the tire width direction, and are arranged in parallel at a predetermined interval in the tire circumferential direction. Further, the sipe 6 on the outermost side in the tire circumferential direction has a closed structure that terminates inside the block 5 at both ends. Thereby, the rigidity of the edge part of the step-on side and kick-out side of the block 5 at the time of tire rolling is ensured.
- the sipe 6 at the center in the tire circumferential direction has a semi-closed structure that opens into the circumferential main groove 22 at one end and terminates inside the block 5 at the other end. . Thereby, the rigidity of the center part of the block 5 is reduced, and the rigidity distribution in the tire circumferential direction of the block 5 is made uniform.
- FIG. 4 is an enlarged view showing a main part of the block shown in FIG.
- FIG. 5 is a cross-sectional view taken along line AA of the ground contact surface of the block illustrated in FIG.
- FIG. 4 shows the positional relationship between the sipe 6, the thin shallow groove 7 and the concave portion 8
- FIG. 5 shows a sectional view of the thin shallow groove 7 and the concave portion 8 in the depth direction.
- the land portions 31 to 33 are provided with a plurality of narrow grooves 7 on the ground contact surface (see FIG. 3).
- the on-ice braking performance of the tire is improved by the thin shallow grooves 7 sucking and removing the water film interposed between the ice road surface and the tread surface when the tire is in contact with the tire.
- the thin shallow groove 7 has a groove width of 0.2 [mm] or more and 0.7 [mm] or less and a groove depth Hg (see FIG. 5) of 0.2 [mm] or more and 0.7 [mm] or less. . For this reason, the narrow shallow groove 7 is shallower than the sipe 6.
- a plurality of shallow grooves 7 are arranged on the entire surface of the land portions 31 to 33.
- a plurality of narrow grooves 7 are arranged over the entire ground contact surface of the shoulder land portion 33.
- the thin shallow groove 7 has a linear shape, and is disposed at a predetermined inclination angle ⁇ (see FIG. 4) with respect to the tire circumferential direction.
- a plurality of shallow grooves 7 are arranged in parallel with a predetermined interval P (see FIG. 4) between each other.
- the thin shallow groove 7 intersects with the sipe 6 and is divided by the sipe 6 in the longitudinal direction.
- the inclination angle ⁇ of the shallow grooves 7 is 20 [deg. ] ⁇ ⁇ ⁇ 80 [deg], preferably 40 [deg] ⁇ ⁇ ⁇ 60 [deg].
- the arrangement interval P (see FIG. 4) of the thin shallow grooves 7 is preferably in the range of 0.5 [mm] ⁇ P ⁇ 1.5 [mm], and 0.7 [mm] ⁇ P ⁇ 1. More preferably, it is in the range of 2 [mm].
- the arrangement density of the narrow shallow grooves 7 is not particularly limited, but is limited by the arrangement interval P described above.
- the arrangement interval P of the thin shallow grooves 7 is defined as the distance between the groove center lines of the adjacent thin shallow grooves 7 and 7.
- the concave portion 8 is a closed depression formed on the ground contact surfaces of the land portions 31 to 33 (a recess not opened at the boundary of the ground contact surface, so-called dimple), and has an arbitrary geometric shape on the ground contact surfaces of the land portions 31 to 33.
- the concave portion 8 may have a polygonal shape such as a circular shape, an elliptical shape, a rectangular shape, or a hexagonal shape.
- the circular or oval concave portion 8 is preferable in that the uneven wear of the ground contact surfaces of the land portions 31 to 33 is small, and the polygonal concave portion 8 is preferable in that the edge component is large and the braking performance on ice and the performance on snow can be improved.
- the opening area of the recess 8 is in the range of 2.5 [mm ⁇ 2] or more and 10 [mm ⁇ 2] or less.
- the diameter of the circular recess 8 is in the range of about 1.8 [mm] to 3.6 [mm].
- the opening area of the recessed portion 8 is the opening area of the recessed portion 8 on the ground contact surfaces of the land portions 31 to 33, and is measured in a state where a tire is mounted on a specified rim to apply a specified internal pressure and no load is applied.
- the depth Hd of the recess 8 (see FIG. 5) and the groove depth Hg of the thin shallow groove 7 preferably have a relationship of 0.5 ⁇ Hd / Hg ⁇ 1.5, and 0.8 ⁇ It is more preferable to have a relationship of Hd / Hg ⁇ 1.2. That is, the depth Hd of the recess 8 and the groove depth Hg of the thin shallow groove 7 are substantially the same. Thereby, the water absorption effect of the ground contact surfaces of the land portions 31 to 33 is improved. Further, since the concave portion 8 is shallower than a sipe (for example, a linear sipe 6 or a circular sipe (not shown)), the rigidity of the land portions 31 to 33 is appropriately ensured. As a result, the braking performance on ice and the performance on snow of the tire are ensured.
- a sipe for example, a linear sipe 6 or a circular sipe (not shown)
- the wall angle ⁇ (see FIG. 5) of the recess 8 is preferably in the range of ⁇ 85 [deg] ⁇ ⁇ ⁇ 95 [deg]. That is, it is preferable that the inner wall of the recess 8 is substantially perpendicular to the ground contact surfaces of the land portions 31 to 33. Thereby, the edge component of the recessed part 8 increases.
- the wall angle ⁇ of the concave portion 8 is measured as an angle formed by the ground contact surfaces of the land portions 31 to 33 and the inner wall of the concave portion 8 in a sectional view of the concave portion 8 in the depth direction.
- the recess 8 is arranged away from the sipe 6. That is, the concave portion 8 and the sipe 6 are arranged at different positions on the ground contact surfaces of the land portions 31 to 33 and do not intersect with each other.
- the distance g between the recess 8 and the sipe 6 is preferably in the range of 0.2 [mm] ⁇ g, and more preferably in the range of 0.3 [mm] ⁇ g. Thereby, the rigidity of the land portions 31 to 33 is ensured appropriately.
- the concave portion 8 is arranged so as to intersect the thin shallow groove 7 and communicate with the thin shallow groove 7. Moreover, the recessed part 8 is arrange
- the plurality of shallow grooves 7 separated from each other means a plurality of shallow grooves 7 extending without intersecting each other in an arrangement pattern of only the shallow grooves 7 excluding the sipes 6 and the recesses 8. Accordingly, an arrangement pattern in which the plurality of thin shallow grooves 7 intersect each other is excluded.
- a plurality of shallow grooves 7 having a linear shape are arranged on the entire surface of the land portion 33 at a predetermined interval P while being inclined at a predetermined angle with respect to the tire circumferential direction.
- the adjacent thin shallow grooves 7 and 7 are arranged in parallel with each other and run in one direction.
- the recessed part 8 is arrange
- the two thin shallow grooves 7 and 7 that run side by side pass through one recess 8 in one direction.
- three or more shallow grooves 7 may penetrate one recess 8 (not shown).
- the number of the concave portions 8 arranged across the plurality of adjacent thin shallow grooves 7 on the grounding surface of one block 5 is based on the total number of the concave portions 8 on the grounding surface. It is preferably 70% or more, more preferably 80% or more. Thereby, the function as a water pool of the above-mentioned recessed part 8 is exhibited effectively.
- all the recesses 8 are disposed across two adjacent thin shallow grooves 7, 7.
- the present invention is not limited to this, and some of the recesses 8 may intersect with the single narrow groove 7 or between the adjacent shallow grooves 7 and 7 without intersecting the shallow groove 7. (Not shown).
- the land portion 33 includes a plurality of sipes 6 that define the narrow shallow grooves 7 on the ground surface. Further, a portion of one narrow shallow groove 7 defined by the sipe 6 extends without penetrating the plurality of recesses 8. That is, the plurality of recesses 8 are distributed and arranged so as not to be overlapped with respect to the portion of the single shallow groove 7 partitioned by the sipe 6. For this reason, only one concave portion 8 is arranged at the maximum in one narrow groove 7 portion.
- the recesses 8 are arranged sparsely as compared with the thin shallow grooves 7.
- the arrangement density Da of the recesses 8 in the entire area of the ground contact surface of one rib or block is in the range of 0.8 [pieces / cm ⁇ 2] ⁇ Da ⁇ 4.0 [pieces / cm ⁇ 2]. It is preferable to be in the range of 1.0 [pieces / cm ⁇ 2] ⁇ Da ⁇ 3.0 [pieces / cm ⁇ 2]. Thereby, the area of the ground contact surface of the land portions 31 to 33 is secured.
- the arrangement density Da of the concave portions 8 is defined as the total number of the concave portions 8 with respect to the area of the ground contact surface of one rib or block.
- the land portion is a rib that is continuous in the tire circumferential direction (not shown)
- the total number of the recesses 8 with respect to the ground contact area of the entire one rib is set to the arrangement density Da.
- the land portion is a block (see FIGS. 2 and 3)
- the total number of the recesses 8 with respect to the ground contact area of one block 5 is set to the arrangement density Da.
- the contact area of the land is determined by the tire and the flat plate when the tire is mounted on the specified rim and applied with the specified internal pressure, and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. Measured at the contact surface.
- the opening area ratio Sc of the recess 8 in the center region CR in the tire width direction defined by the continuous contact surface, and the opening area ratio Se of the recess 8 in the end region in the tire width direction Have a relationship of Se ⁇ Sc. That is, the opening area ratio Sc of the recess 8 in the central region CR (see FIG. 3) in the tire width direction is larger than that in the end region. Further, the ratio Sc / Se of the opening area ratios of the recesses 8 preferably has a relationship of 1.50 ⁇ Sc / Se, and more preferably has a relationship of 3.00 ⁇ Sc / Se.
- the upper limit of the ratio Sc / Se is not particularly limited, but is limited by the relationship between the arrangement density of the recesses 8 and the opening area.
- Se 0 and the condition of Se ⁇ Sc is satisfied.
- the contact surface is the contact surface between the tire and the flat plate when the tire is mounted on the specified rim to apply the specified internal pressure and when the load corresponding to the specified load is applied in a stationary state perpendicular to the flat plate. Defined.
- a continuous ground plane is defined as a ground plane partitioned by grooves having a groove width of 2.0 [mm] or more and a groove depth of 3.0 [mm] or more.
- the ground contact surface of one rib or one block defined by the circumferential groove and the lug groove having the groove width and the groove depth corresponds to the continuous ground contact surface.
- a closed structure lug groove that terminates in the land part, a partial notch formed in the land part (for example, a notch part 311 in FIG. 7 described later), a sipe or kerf that closes when the tire touches, It does not correspond to the above groove because it does not divide the ground contact surface.
- the central region in the tire width direction is defined as the region of the central portion 50 [%] in the tire width direction of the continuous contact surface (see FIG. 3).
- the end region in the tire width direction is defined as the region of the left and right end portions 25 [%] in the tire width direction of the continuous contact surface.
- the land portion is a rib that is continuous in the tire circumferential direction (not shown)
- a center region and an end region in the tire width direction are defined for the ground contact surface of one entire rib.
- the land portion is a block row (see FIG. 2)
- a center region and an end region are respectively defined for the ground contact surfaces of the blocks constituting the block row.
- the broken line of FIG. 3 has shown the boundary line of a center part area
- the opening area ratio of the recess is defined as a ratio between the sum of the opening areas of the recesses arranged in the predetermined region and the ground contact area of the region.
- the opening area of the recess and the contact area of the area are determined when the tire is mounted on the specified rim and applied with the specified internal pressure, and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. It is measured at the contact surface between the tire and the flat plate.
- the land portion is composed of a plurality of blocks arranged in the tire circumferential direction (see FIG. 2), 70 [%] or more, preferably 80 [%] or more blocks 5 constituting one block row are included. It is preferable to satisfy the condition Se ⁇ Sc of the opening area ratio of the recess 8 described above. On the other hand, in the entire tread, it is sufficient that at least one row of land portions satisfies the condition of the block row.
- the opening area ratio of the recesses 8 in the central region and the end region can be adjusted by the arrangement density of the recesses 8 in each region. That is, the recesses 8 are densely arranged in the central region in the tire width direction and sparsely arranged in the end region in the tire width direction, so that the opening area ratio Sc of the concave portion 8 in the central region is set large.
- the arrangement number Nc of the recesses 8 in the central region CR in the tire width direction of one block 5 and the arrangement of the recesses 8 in the end region in the tire width direction (reference numerals omitted in the drawing). Since the number Ne has a relationship of Ne ⁇ Nc, the condition Se ⁇ Sc of the opening area ratio of the recess 8 is satisfied. That is, the plurality of recesses 8 are connected to one rib or one block so that the arrangement density of the recesses 8 in one rib or one block is different between the center region CR and the end region in the tire width direction. It is unevenly distributed in the ground.
- the ratio Nc / Ne of the number of the recessed portions 8 is preferably 1.50 ⁇ Nc / Ne, and more preferably 3.00 ⁇ Nc / Ne.
- the number of recesses arranged is counted as the number of center points of recesses in a predetermined area. Therefore, even if a part of the recess protrudes from the region, if the center point of the recess is within the region, it can be said that the recess is disposed in the region.
- the land portion is composed of a plurality of blocks arranged in the tire circumferential direction (see FIG. 2), 70 [%] or more, preferably 80 [%] or more blocks 5 constituting one block row are included. It is preferable to satisfy the conditions Se ⁇ Sc and Ne ⁇ Nc of the recess 8 described above. On the other hand, in the entire tread, it is sufficient that at least one row of land portions satisfies the condition of the block row.
- the central area of the block 5 is defined as the area of the central portion 50 [%] of the ground plane of the block 5, in one block 5, the ground area and the end area of the central area The ground contact area is substantially equal if notches and narrow grooves are excluded. For this reason, in the configuration in which the recesses 8 of the block 5 have the same opening area, the sum of the opening areas of the recesses 8 in the end region is the recess in the central region according to the condition Ne ⁇ Nc of the number of the recesses 8 arranged. It becomes larger than the sum total of the opening area of 8.
- the concave portions 8 are densely arranged in the central region CR of the block 5 where the ground pressure is low. Then, the contact area of the central region CR decreases, the contact pressure increases, and the snow column shearing force (so-called digging force) by the recess 8 increases. Thereby, the traction performance of the tire is improved, and the performance on snow of the tire is improved. Further, since the recesses 8 are sparsely arranged in the end region, the ground contact area of the end region of the block 5 is ensured. Thereby, the adhesion action (adhesion with respect to an ice road surface) of an edge part area
- the shoulder land portion 33 (defined as a land portion on the outer side in the tire width direction defined in the outermost circumferential main groove) has a great influence on the braking performance of the tire. Therefore, as shown in FIG. 3, the block 5 of the shoulder land portion 33 has the concave portion 8 densely in the central region CR in the tire width direction, so that the effect of improving the braking performance on snow by the concave portion 8 is significantly obtained.
- one block 5 of the shoulder land portion 33 has a total of 11 recesses 8 in the ground contact surface, and 7 blocks in the center region CR in the tire width direction of the ground contact surface.
- a recess 8 is provided, and a total of four recesses 8 are provided in the left and right end regions.
- each recessed part 8 has the same opening shape and the same opening area.
- the recesses 5 of all the blocks 5 satisfy the condition of the number Nc (see FIG. 2).
- the block 5 of the shoulder land portion 33 has a rectangular grounding surface.
- a plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the block 5 into a plurality of sections in the tire circumferential direction. All sections have at least one recess 8.
- the recesses 8 are concentrated in the central region CR of the block 5 in the tire width direction, and are arranged in the end region on the outermost circumferential main groove 22 side. Not placed.
- the concave portions 8 are respectively disposed at corner portions of the block 5 on the circumferential main groove 22 side.
- the recesses 8 are arranged only at the corners and are not arranged in the central region CR in the tire width direction.
- the corners of the land portions 31 to 33 are defined as 5 [mm] square areas including the corner portions of the land contact surface.
- the corner portion of the land portion includes not only the land portion defined by the main groove and the lug groove but also the land portion defined by the notch formed in the land portion. Moreover, if the center of the recessed part 8 exists in said corner
- any three sections adjacent in the tire circumferential direction include a section having a recess 8 in the end region in the tire width direction and a section having a recess 8 in the center region CR in the tire width direction. And each.
- the recesses 8 are distributed and arranged in the end region and the center region CR of the land portions 31 to 33.
- the section of the both ends of the block 5 in the tire circumferential direction refers to a pair of sections located at both ends in the tire circumferential direction among the plurality of sections of the block 5 partitioned in the tire circumferential direction by the plurality of sipes 6. Moreover, the section of the center part of the tire circumferential direction of the block 5 means the area except the section of the both ends of the said tire circumferential direction.
- the sipe 6 is arranged parallel to the lug groove 43 or slightly inclined, and is arranged only in the inner region in the tire width direction from the tire ground contact end T. Further, the narrow shallow groove 7 extends beyond the tire ground contact end T to a region outside the land portion 33 in the tire width direction. Further, the concave portion 8 is disposed only in a region on the inner side in the tire width direction from the tire ground contact end T.
- the tire ground contact edge T is the contact between the tire and the flat plate when a load corresponding to the predetermined load is applied by attaching the tire to the specified rim and applying the specified internal pressure and placing the tire perpendicularly to the flat plate in a stationary state.
- FIG. 6 and 7 are explanatory views showing the land portion of the pneumatic tire shown in FIG.
- FIG. 6 shows a plan view of one block 5 constituting the second land portion 32.
- FIG. 7 shows a plan view of one block 5 constituting the center land portion 31.
- the second land portion 32 is divided in the tire width direction by one circumferential narrow groove 23, and further divided in the tire circumferential direction by a plurality of lug grooves 42, thereby dividing the plurality of blocks 5. ing. Further, a block 5 that is long in the tire circumferential direction is formed in a region on the inner side in the tire width direction of the second land portion 32, and a short block 5 is formed in a region on the outer side in the tire width direction.
- the second land portion 32 is defined as a land portion on the inner side in the tire width direction that is partitioned by the outermost circumferential main groove 22.
- one block 5 on the outer side in the tire width direction of the second land portion 32 has a rectangular contact surface.
- a plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the block 5 into a plurality of sections. All sections have at least one recess 8.
- the recessed part 8 is arrange
- the recessed part 8 is each arrange
- one block 5 has a total of ten concave portions 8 in the ground contact surface, and has a total of eight concave portions 8 in the left and right end regions in the tire width direction, and a central portion in the tire width direction.
- the region CR has two recesses 8.
- each recessed part 8 has the same opening shape and the same opening area.
- the recesses 8 of all the blocks 5 of the second land portion 32 satisfy the above-described condition Ne ⁇ Nc.
- the block 5 has the recesses 8 in all the sections of the block 5 partitioned by the sipe 6, so that the water film on the ice road surface is efficiently absorbed and the braking performance of the tire on ice is ensured. Is done.
- the second land portion 32 has a great influence on the braking / driving performance of the tire. Therefore, as shown in FIG. 6, the block 5 of the second land portion 32 has the recesses 8 sparsely in the end region in the tire width direction, so that the contact area of the end region in the tire width direction of the block 5 is secured. . Thereby, the adhesion action of the end region is ensured, and the performance on ice of the tire is ensured.
- the center land portion 31 is divided in the tire circumferential direction by a plurality of lug grooves 41, and a plurality of blocks 5 are partitioned. Further, the block 5 has a notch 311 on the extension line of the lug groove 42 of the second land portion 32. The block 5 has a rectangular grounding surface.
- the center land portion is defined as a land portion 31 (see FIG. 2) on the tire equator plane CL or a land portion (not shown) adjacent to the tire equator plane CL.
- a plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the block 5 into a plurality of sections.
- the block 5 has a section that does not have the recess 8.
- any three adjacent sections include a section having no recess 8.
- sections having recesses 8 only at both ends in the tire width direction of the block 5 and sections having no recesses 8 are alternately arranged in the tire circumferential direction.
- the recesses 8 are disposed at the four corners of the block 5, respectively.
- the recessed part 8 is arrange
- the section including the notch 311 has a recess 8 in the vicinity of the notch 311.
- the concave portion 8 is not disposed except for the vicinity of the corner portion and the notch portion 311 described above.
- one block 5 has a total of 17 recesses 8 in the contact surface, and the number Nc of the recesses 8 arranged in the center region CR in the tire width direction of the block 5 is 9, and the tire width The number Ne of the recessed portions 8 in the end region in the direction is eight.
- each recessed part 8 has the same opening shape and the same opening area.
- the recessed parts 8 of all the blocks 5 satisfy
- the center land portion 31 has high rigidity in order to ensure the steering stability performance of the tire. Therefore, as shown in FIG. 7, the block 5 of the center land portion 31 partially has a section that does not have the recess 8, whereby the rigidity of the block 5 is ensured and the steering stability performance of the tire is ensured.
- the center land portion 31 has a great influence on the tire driving performance. Therefore, as shown in FIG. 7, when the block 5 of the center land portion 31 has the concave portion 8 densely in the center region CR in the tire width direction, the contact area of the center region CR decreases and the contact pressure increases. Thus, the snow column shearing force by the recess 8 increases. Thereby, the traction performance of the tire is improved, and the improvement effect of the tire driving performance is remarkably obtained.
- the tire molding die has a plurality of vent devices (not shown) on the die surface for molding the ground contact surfaces of the land portions 31 to 33. Also, a certain type of vent device forms a vent hole (small depression) on the ground contact surface of the land portions 31 to 33 after vulcanization molding. Therefore, by using this vent hole as the concave portion 8, the vent hole is effectively used, and unnecessary depressions in the ground contact surfaces of the land portions 31 to 33 are reduced to reduce the ground contact area of the land portions 31 to 33. Properly secured.
- [Modification 1] 8 to 14 are explanatory views showing modifications of the pneumatic tire shown in FIG. These drawings show the positional relationship between the sipe 6, the thin shallow groove 7, and the recess 8.
- the narrow shallow grooves 7 are arranged to be inclined at a predetermined angle ⁇ with respect to the tire circumferential direction.
- Such a configuration is preferable in that the inclined thin shallow grooves 7 cause edge components in both the tire circumferential direction and the tire width direction.
- the present invention is not limited to this, and the shallow groove 7 may extend in parallel to the tire circumferential direction (see FIG. 8) or may extend in parallel to the tire width direction (see FIG. 9).
- the thin shallow groove 7 has a linear shape. Such a configuration is preferable in that the thin shallow groove 7 can be easily formed.
- the present invention is not limited to this, and the thin shallow groove 7 may have a zigzag shape (see FIG. 10) or a wavy shape (see FIG. 11).
- the plurality of thin shallow grooves 7 may be arranged with the phases aligned with each other, or may be arranged with the phases shifted from each other as shown in FIG.
- the thin shallow groove 7 may have a short structure that is bent or curved.
- the short thin shallow grooves 7 may be arranged while being offset from each other (see FIG. 13), or may be arranged in a matrix (not shown).
- the thin shallow groove 7 may have an arc shape (see FIG. 14), or may have a curved shape such as an S shape (not shown).
- the shallow groove 7 may be inclined at a predetermined angle ⁇ with respect to the tire circumferential direction, or the tire circumferential direction May extend parallel to the tire width or may extend parallel to the tire width direction.
- the inclination angle ⁇ of the thin shallow groove 7 is measured with reference to the center of the amplitude of the zigzag shape or the wavy shape.
- 15 and 16 are explanatory views showing a modification of the pneumatic tire shown in FIG. These drawings show the positional relationship between the sipe 6, the thin shallow groove 7, and the recess 8.
- the thin shallow groove 7 has a linear structure extending in a predetermined direction. Such a configuration is preferable in that the thin shallow groove 7 can extend continuously over the entire area of the ground contact surface of the block 5.
- the thin shallow grooves 7 may have an annular structure and be arranged at a predetermined interval from each other.
- the thin shallow groove 7 may have a polygonal shape (not shown) such as a circular shape (FIG. 15), an elliptical shape (not shown), a rectangular shape (FIG. 16), a triangular shape, a hexagonal shape, or the like.
- the concave portion 8 is disposed across a plurality of adjacent thin shallow grooves 7 and 7 separated from each other.
- FIG. 17 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. This figure shows a cross-sectional view in the depth direction of the narrow shallow grooves 7a and 7b and the recess 8.
- the groove depth of some of the thin shallow grooves 7b is set to be shallower than the groove depth Hg of the reference thin shallow groove 7a.
- the thin shallow groove 7b having the shallow groove depth disappears first and the thin shallow groove 7a having the deep groove depth Hg disappears after the tire wear progresses. Thereby, the property change of the block 5 by all the thin shallow grooves 7 disappearing simultaneously can be suppressed.
- FIG. 18 to 21 are explanatory views showing modifications of the pneumatic tire shown in FIG. These drawings show the positional relationship between the sipe 6, the thin shallow groove 7, and the recess 8.
- the present invention is not limited to this, and as shown in FIGS. 18 to 21, the thin shallow grooves 7 may be arranged so as to intersect or communicate with each other.
- a plurality of narrow grooves 7 may be arranged in a mesh shape.
- the thin shallow grooves 7 may be arranged to be inclined with respect to the tire circumferential direction and the tire width direction (FIG. 18), or may be arranged in parallel to the tire circumferential direction and the tire width direction. (FIG. 19).
- some of the shallow grooves 7 may be arranged curved, for example, in an arc shape or a wave shape (FIG. 20).
- the narrow shallow grooves 7 may have an annular structure and be arranged in communication with each other (FIG. 21).
- the thin shallow grooves 7 are arranged in a honeycomb shape.
- the recessed part 8 is arrange
- FIG. 22 shows a plan view of one block 5 constituting the shoulder land portion 33
- FIG. 23 shows a plan view of one block 5 constituting the second land portion 32
- FIG. The top view of the one block 5 which comprises the center land part 31 is shown.
- the opening area ratio Sc of the recess 8 in the central region CR in the tire width direction defined for the continuous ground contact surface is the opening area ratio of the recess 8 in the end region in the tire width direction.
- a plurality of recesses 8 are unevenly arranged in the ground plane of one block 5 so as to be larger than Se (Se ⁇ Sc).
- the number Ne of the recessed portions 8 in the end region in the direction has a relationship Ne ⁇ Nc.
- the opening area ratio Sc ′ of the recess 8 in the central region CR ′ in the tire circumferential direction defined by the continuous contact surface and the end in the tire circumferential direction has a relationship of Se ′ ⁇ Sc ′.
- the ratio Sc ′ / Se ′ of the opening area ratio of the recess 8 preferably has a relationship of 1.50 ⁇ Sc ′ / Se ′, and more preferably has a relationship of 3.00 ⁇ Sc ′ / Se ′. preferable.
- the central region CR ′ in the tire circumferential direction is defined as the region of the central portion 50 [%] in the tire circumferential direction of the continuous contact surface (see FIG. 22).
- the end region in the tire circumferential direction is defined as the region of the end portion 25 [%] of the continuous contact surface on the front and rear sides in the tire circumferential direction.
- These central region and end region are defined excluding partial cutouts formed in the land portions 31 to 33.
- a center area and an end area are defined for the ground plane of each block 5 constituting the block row.
- the broken line of FIG. 22 has shown the boundary line of a center part area
- the arrangement number Nc ′ of the recesses 8 in the central region CR ′ in the tire circumferential direction of one block 5 and the arrangement number Ne of the recesses 8 in the end region in the tire circumferential direction are shown. Since “and Ne” ⁇ Nc ′, the condition Se ′ ⁇ Sc ′ of the opening area ratio of the recess 8 is satisfied. Further, the ratio Nc ′ / Ne ′ of the number of the recessed portions 8 is preferably 1.50 ⁇ c ′ / Ne ′, more preferably 3.00 ⁇ Nc ′ / Ne ′. .
- the land portion is composed of a plurality of blocks arranged in the tire circumferential direction (see FIG. 2), 70 [%] or more, preferably 80 [%] or more blocks 5 constituting one block row are included. It is preferable to satisfy the conditions Ne ′ ⁇ Nc ′ and Se ′ ⁇ Sc ′ of the recess 8 described above. On the other hand, in the entire tread, it is sufficient that at least one row of land portions satisfies the condition of the block row.
- the concave portions 8 are densely arranged in the central region CR of the block 5 where the ground pressure is low. Then, the contact area of the central region CR decreases, the contact pressure increases, and the snow column shearing force (so-called digging force) by the recess 8 increases. Thereby, the traction performance of the tire is improved, and the performance on snow of the tire is improved. Further, since the recesses 8 are sparsely arranged in the end region, the ground contact area of the end region of the block 5 is ensured. Thereby, the adhesion action of the end region is ensured, and the performance on ice of the tire is ensured.
- one block 5 of the shoulder land portion 33 has a total of 11 recesses 8 in the ground contact surface, and 7 recesses 8 in the central region CR ′ in the tire circumferential direction. And a total of four recesses 8 in the front and rear end regions (reference numerals omitted in the figure) in the tire circumferential direction.
- each recessed part 8 has the same opening shape and the same opening area.
- the concave portions 8 of all the blocks 5 satisfy the above-described condition Nc ' ⁇ Ne'.
- the shoulder land portion 33 has a great influence on the braking performance of the tire. Therefore, the block 5 of the shoulder land portion 33 has the concave portion 8 densely in the central region CR ′ in the tire circumferential direction, whereby the effect of improving the braking performance on snow by the concave portion 8 can be obtained remarkably.
- one block 5 (see FIG. 2) on the outer side in the tire width direction of the second land portion 32 has a total of nine recesses 8 in the ground contact surface, and also in the tire circumferential direction.
- the central region CR ′ has five recesses 8 and the front and rear end regions (reference numerals omitted in the figure) have four recesses 8 in the tire circumferential direction.
- each recessed part 8 has the same opening shape and the same opening area.
- the concave portions 8 of all the blocks 5 satisfy the above-described condition Ne ' ⁇ Nc'.
- the second land portion 32 (defined as the land portion on the inner side in the tire width direction defined by the outermost circumferential main groove 22) has a great influence on the braking / driving performance of the tire. Therefore, as shown in FIG. 6, the block 5 of the second land portion 32 has the recesses 8 sparsely in the end region in the tire width direction, so that the contact area of the end region in the tire width direction of the block 5 is secured. . Thereby, the adhesion action of the end region is ensured, and the performance on ice of the tire is ensured.
- the center land 31 has a great influence on the driving performance of the tire. Therefore, the block 5 of the center land portion 31 has the concave portion 8 densely in the central region CR ′ in the tire circumferential direction, so that the ground contact area of the central region CR ′ decreases, the ground pressure increases, and the concave portion 8 Increases the shear force due to snow column. Thereby, the traction performance of a tire improves and the improvement effect of the tire drive performance by the recessed part 8 is acquired notably.
- FIG. 25 to 28 are explanatory views showing modifications of the pneumatic tire shown in FIG.
- FIG. 25 shows a plan view of the tread surface of the pneumatic tire 1.
- 26 shows a plan view of one block 5 constituting the shoulder land portion 33
- FIG. 27 shows a plan view of one block 5 constituting the second land portion 32
- FIG. The top view of the one block 5 which comprises the part 31 is shown.
- the plurality of recesses 8 are unevenly distributed in the ground contact surface of one block 5, whereby the recesses 8 in the central region CR in the tire width direction of one block 5.
- the recesses 8 are densely arranged in the central region CR of the block 5 in the tire width direction.
- the concave portions 8 of the land portions 31 to 33 have the same opening shape and the same opening area.
- the present invention is not limited to this, and the opening area ratio of the recesses 8 in the central region in the tire width direction of one rib or block by changing the opening area of the plurality of recesses 8 within the ground contact surface of one rib or block.
- Sc may be set larger than the opening area ratio Se of the recess 8 in the end region in the tire width direction (Se ⁇ Sc). That is, the recess 8 having a relatively large opening area is disposed in the center region CR in the tire width direction.
- the average value Ac of the opening area of the recess 8 in the center region CR in the tire width direction and the recess 8 in the end region in the tire width direction (reference numerals omitted in the drawings). Since the average value Ae of the opening area has a relationship of Ae ⁇ Ac, the condition Se ⁇ Sc of the opening area ratio of the recess 8 is satisfied.
- the ratio Ac / Ae of the average values Ac and Ae of the opening areas of the recesses 8 preferably has a relationship of 1.5 ⁇ Ac / Ae ⁇ 4.0, and 2.0 ⁇ Ac / Ae ⁇ 3.0 It is more preferable to have this relationship.
- Ae 0, and the conditions of Ae ⁇ Ac and Se ⁇ Sc are satisfied.
- the average values Ac and Ae of the opening areas are calculated as a ratio between the sum of the opening areas of the recesses in the predetermined region and the total number of recesses in the region.
- the land portion is composed of a plurality of blocks arranged in the tire circumferential direction (see FIG. 2), 70 [%] or more, preferably 80 [%] or more blocks 5 constituting one block row are included. It is preferable that the above-described conditions for the opening area of the recess 8 Ac ⁇ Ae and Sc ⁇ Se are satisfied. On the other hand, in the entire tread, it is sufficient that at least one row of land portions satisfies the conditions Ac ⁇ Ae and Sc ⁇ Se of the opening area of the concave portion 8 described above.
- the recess 8 having a relatively large opening area is disposed in the central region CR of the block 5 where the ground pressure is low. Then, the contact area of the central region CR decreases, the contact pressure increases, and the snow column shearing force (so-called digging force) by the recess 8 increases. Thereby, the traction performance of the tire is improved, and the performance on snow of the tire is improved. Moreover, since the recessed part 8 which has a comparatively small opening area is arrange
- one block 5 of the shoulder land portion 33 has a total of 16 recesses 8 in the ground contact surface, and also has a center region CR and an end region (in the drawing) in the tire width direction. Each of which has eight recesses 8. Moreover, each recessed part 8 has the same opening shape. In addition, the concave portion 8 having a relatively large opening area is disposed in the central region CR, and conversely, the concave portion 8 having a relatively small opening area is disposed in the end region. Accordingly, the condition Ae ⁇ Ac of the opening area of the recess 8 and the condition Se ⁇ Sc of the opening area ratio are simultaneously satisfied in each region. In the shoulder land portion 33, the concave portions 8 of all the blocks 5 satisfy the above conditions Ae ⁇ Ac and Se ⁇ Sc (see FIG. 25).
- one block 5 (see FIG. 25) on the outer side in the tire width direction of the second land portion 32 has a total of 16 recesses 8 in the ground contact surface, and also in the tire width direction.
- the left and right central region CR and the end region each have eight concave portions 8.
- each recessed part 8 has the same opening shape.
- the concave portion 8 having a relatively large opening area is disposed in the central region CR, and conversely, the concave portion 8 having a relatively small opening area is disposed in the end region.
- the condition Ae ⁇ Ac of the opening area of the recess 8 and the condition Se ⁇ Sc of the opening area ratio are simultaneously satisfied in each region.
- the concave portions 8 of all the blocks 5 satisfy the above conditions Ae ⁇ Ac and Se ⁇ Sc (see FIG. 25).
- one block 5 of the center land portion 31 has a total of 35 recesses 8 in the ground contact surface, and 17 recesses 8 in the center region CR in the tire width direction. And has a total of 18 recesses 8 in the end region in the tire width direction (reference numerals omitted in the figure).
- each recessed part 8 has the same opening shape.
- the concave portion 8 having a relatively large opening area is disposed in the central region CR, and conversely, the concave portion 8 having a relatively small opening area is disposed in the end region.
- the condition Ae ⁇ Ac of the opening area of the recess 8 and the condition Se ⁇ Sc of the opening area ratio are simultaneously satisfied in each region.
- the recessed part 8 of all the blocks 5 satisfy
- 70 [%] or more, preferably 80 [%] or more of the recesses 8 arranged in the central region CR in the tire width direction is the average opening area of the recesses 8 arranged in the block 5. It is preferable to have an opening area larger than the value. That is, most of the large concave portion 8 is disposed in the central region CR. As a result, the effect of increasing the snow column shear force by the recess 8 can be obtained efficiently during traveling on a snowy road surface.
- one block 5 includes two types of recesses 8 having different opening areas, and all the recesses 8 having a large opening area are arranged in the central region CR. Yes.
- region has the recessed part 8 of a mutually different magnitude
- the present invention is not limited to this, and some small concave portions may be arranged in the central region CR (not shown).
- the concave portion 8 having an opening area smaller than the average value is disposed on the outermost side in the tire width direction on the continuous contact surface.
- the ground contact area of the end region of the block 5 is secured, and the adhesion of the end region to the ice road surface is secured. Thereby, the performance on ice of a tire is ensured.
- the small concave portion 8 is arranged along the edge portion of the block 5 on the circumferential groove 21 to 23 side. Thereby, the ground contact area of the end region is ensured.
- the land portions 31 to 33 are block rows having a plurality of blocks 5, and the plurality of sipes 6 are arranged in parallel in the tire circumferential direction and divide the land portions 31 to 33 into a plurality of sections. And a plurality of types of recesses 8 having different opening areas.
- the recess 8 having an opening area larger than the average value is disposed in at least one of any three sections adjacent in the tire circumferential direction. That is, any three adjacent sections defined by the sipe 6 have at least one large recess 8.
- the big recessed part 8 is disperse
- all the sections defined by the sipe 6 have the large recesses 8.
- the recessed part 8 is disperse
- the land portions 31 to 33 are block rows having a plurality of blocks 5, and the recesses 8 having an opening area smaller than the average value are preferably arranged at the corners of the blocks 5. .
- the ground contact area of the corner is ensured, and the adhesion of the corner to the ice road surface is ensured. Thereby, the performance on ice of a tire is ensured.
- small concave portions 8 are arranged at the corners of all the blocks 5 formed at the intersecting positions of the circumferential grooves 21 to 23 and the lug grooves 41 to 43 (see FIG. 25).
- small concave portions 8 are also arranged at the corners of the cutout portions 311 formed in the center land portion 33 (see FIG. 28). Thereby, the ground contact area of the corner is ensured.
- the arrangement number Nc of the concave portions 8 in the central region CR of each block 5 and the arrangement number Ne of the concave portions 8 in the end region are substantially the same, and the number of the concave portions 8 in each region is the same.
- the arrangement density is set to be substantially the same.
- the present invention is not limited to this, and in addition to the above condition Ae ⁇ Ac, more preferably 1 so that the ratio Nc / Ne of the number of the recessed portions 8 in each region has a relationship of 1.20 ⁇ Nc / Ne. .50 ⁇ Nc / Ne may be set. That is, in the central region CR in the tire width direction, the recesses 8 are densely arranged with a relatively large opening area. This makes it possible to efficiently adjust the condition Se ⁇ Sc of the opening area ratio of the recess 8 in each region while reducing the ratio Ac / Ae of the opening area of the recess 8 in each region.
- FIGS. 29 to 31 are explanatory views showing modifications of the pneumatic tire shown in FIG.
- FIG. 29 shows a plan view of one block 5 constituting the shoulder land portion 33
- FIG. 30 shows a plan view of one block 5 constituting the second land portion 32
- FIG. The top view of the one block 5 which comprises the center land part 31 is shown.
- the opening area ratio Sc of the recess 8 in the central region in the tire width direction of one rib or block is equal to the recess 8 in the end region in the tire width direction.
- the plurality of recesses 8 change the opening area within the ground contact surface of one rib or block so as to be larger than the opening area ratio Se of (Se ⁇ Sc).
- the present invention is not limited to this, and the opening area ratio Sc ′ of the recess 8 in the center region CR ′ in the tire circumferential direction of one rib or block is larger than the opening area ratio Se ′ of the recess 8 in the end region in the tire circumferential direction.
- the plurality of recesses 8 may change the opening area within the ground contact surface of one rib or block so as to be large (Se ′ ⁇ Sc ′). That is, the recess 8 having a relatively large opening area is disposed in the central region CR ′ in the tire circumferential direction.
- the average value Ac ′ of the opening area of the recess 8 in the central region CR ′ in the tire circumferential direction and the recess in the end region in the tire circumferential direction (reference numerals omitted in the drawings). Since the average value Ae ′ of the opening area of 8 has a relationship of Ae ′ ⁇ Ac ′, the condition Se ′ ⁇ Sc ′ of the opening area ratio of the recess 8 is satisfied.
- the ratio Ac ′ / Ae ′ of the average values Ac ′ and Ae ′ of the opening area of the recess 8 preferably has a relationship of 1.5 ⁇ Ac ′ / Ae ′ ⁇ 4.0, and 2.0 ⁇ Ac It is more preferable to have a relationship of “/Ae” ⁇ 3.0.
- Ae ′ 0, and the conditions of Ae ′ ⁇ Ac ′ and Se ′ ⁇ Sc ′ are satisfied.
- the land portion is composed of a plurality of blocks arranged in the tire circumferential direction (see FIG. 2), 70 [%] or more, preferably 80 [%] or more blocks 5 constituting one block row are included. It is preferable that the above-described conditions Ae ′ ⁇ Ac ′ and Se ′ ⁇ Sc ′ for the opening area of the recess 8 are satisfied. On the other hand, in the entire tread, it is sufficient that at least one row of land portions satisfies the condition of the block row.
- the recess 8 having a relatively large opening area is disposed in the central region CR of the block 5 where the ground pressure is low. Then, the contact area of the central region CR decreases, the contact pressure increases, and the snow column shearing force (so-called digging force) by the recess 8 increases. Thereby, the traction performance of the tire is improved, and the performance on snow of the tire is improved. Moreover, since the recessed part 8 which has a comparatively small opening area is arrange
- one block 5 of the shoulder land portion 33 has a total of 16 recesses 8 in the ground contact surface, and also has a central region CR ′ and an end region (in the drawing) in the tire circumferential direction. Each of which has eight recesses 8. Moreover, each recessed part 8 has the same opening shape. Further, the concave portion 8 having a relatively large opening area is disposed in the central region CR ′, and conversely, the concave portion 8 having a relatively small opening area is disposed in the end region. Accordingly, the condition Ae ′ ⁇ Ac ′ for the opening area of the recess 8 and the condition Se ′ ⁇ Sc ′ for the opening area ratio are simultaneously satisfied in each region. Further, in the entire shoulder land portion 33, the concave portions 8 of all the blocks 5 satisfy the above-described conditions Ae ' ⁇ Ac' and Se ' ⁇ Sc'.
- one block 5 located on the outer side in the tire circumferential direction of the second land portion 32 has a total of 16 recesses 8 in the ground contact surface.
- the left and right central region CR ′ and the end region each have eight concave portions 8.
- each recessed part 8 has the same opening shape.
- the concave portion 8 having a relatively large opening area is disposed in the central region CR ′, and conversely, the concave portion 8 having a relatively small opening area is disposed in the end region.
- condition Ae ′ ⁇ Ac ′ for the opening area of the recess 8 and the condition Se ′ ⁇ Sc ′ for the opening area ratio are simultaneously satisfied in each region. Further, in the entire second land portion 32, the concave portions 8 of all the blocks 5 satisfy the above conditions Ae ' ⁇ Ac' and Se ' ⁇ Sc'.
- one block 5 of the center land portion 31 has a total of 36 recesses 8 in the ground plane, and also has a central region CR ′ in the tire circumferential direction and left and right end regions. (Reference numerals omitted in the figure) each have 18 recesses 8. Moreover, each recessed part 8 has the same opening shape. Further, the concave portion 8 having a relatively large opening area is disposed in the central region CR ′, and conversely, the concave portion 8 having a relatively small opening area is disposed in the end region.
- condition Ae ′ ⁇ Ac ′ for the opening area of the recess 8 and the condition Se ′ ⁇ Sc ′ for the opening area ratio are simultaneously satisfied in each region. Further, in the entire center land portion 31, the concave portions 8 of all the blocks 5 satisfy the above-described conditions Ae ' ⁇ Ac' and Se ' ⁇ Sc'.
- the recessed part 8 of 70 [%] or more, preferably 80 [%] or more arranged in the central region CR ′ in the tire circumferential direction has an opening area larger than the average value. . That is, most of the large concave portion 8 is disposed in the central region CR ′.
- one block 5 includes two types of recesses 8 having different opening areas, and all the recesses 8 having a large opening area are arranged in the central region CR ′. ing.
- region has the recessed part 8 of a mutually different magnitude
- the present invention is not limited to this, and some small concave portions may be disposed in the central region CR ′.
- the concave portion 8 having an opening area smaller than the average value is disposed on the outermost side in the tire circumferential direction on the continuous contact surface.
- region of the block 5 is ensured, and the adhesion effect
- the small concave portion 8 is disposed along the edge portion of the block 5 on the lug groove 41, 42 side. Thereby, the ground contact area of the end region is ensured.
- the land portions 31 to 33 are block rows having a plurality of blocks 5, and the recesses 8 having an opening area smaller than the average value are preferably arranged at the corners of the blocks 5. .
- the contact area of the corner is ensured, and the adhesion of the corner is ensured. Thereby, the performance on ice of a tire is ensured.
- small concave portions 8 are arranged at the corners of all the blocks 5 formed at the intersection positions of the circumferential grooves 21 to 23 and the lug grooves 41 to 43 (see FIG. 25). Has been. Thereby, the ground contact area of the corner is ensured.
- the arrangement number Nc ′ of the recesses 8 in the central region CR ′ of each block 5 and the arrangement number Ne ′ of the recesses 8 in the end region are substantially the same.
- the arrangement density of the recesses 8 is set to be substantially the same.
- the present invention is not limited to this, and in addition to the above condition Ae ′ ⁇ Ac ′, the ratio Nc ′ / Ne ′ of the number of recesses 8 in each region has a relationship of 1.20 ⁇ Nc ′ / Ne ′. More preferably, it may be set to have a relationship of 1.50 ⁇ Nc ′ / Ne ′. That is, in the central region CR ′ in the tire circumferential direction, the recesses 8 are densely arranged with a relatively large opening area. Accordingly, the condition Se ′ ⁇ Sc ′ of the opening area ratio of the recess 8 in each region can be efficiently adjusted while reducing the ratio Ac ′ / Ae ′ of the opening area of the recess 8 in each region.
- the pneumatic tire 1 includes land portions 31 to 33 having ribs or a plurality of blocks on the tread surface (see FIGS. 2 and 25).
- the land portions 31 to 33 include a plurality of narrow grooves 7 and a plurality of recesses 8 on the ground contact surface (see FIGS. 3 and 4).
- the region of the center part 50 [%] in the tire width direction of the continuous contact surface in the land portions 31 to 33 is defined as the center region
- the region of the left and right end portions 25 [%] in the tire width direction is defined as the end portion.
- the opening area ratio Sc of the recess 8 in the central region CR in the tire width direction of one continuous ground contact surface and the opening area ratio Se of the recess 8 in the end region in the tire width direction are: It has a relationship of Se ⁇ Sc.
- the opening area ratio of the recess 8 is set to be small in the end region in the tire width direction, a ground contact area in the end region of the block 5 is ensured.
- the concave portion 8 is shallower than a sipe (for example, a linear sipe 6 or a circular sipe (not shown)), the rigidity of the land portions 31 to 33 is appropriately ensured.
- the opening area ratio Sc of the recess 8 in the center region CR in the tire width direction and the opening area ratio Se of the recess 8 in the end region in the tire width direction are 1.50 ⁇ Sc. / Se relationship.
- the ratio Sc / Se of the opening area ratio of the recess 8 in each region is ensured, and there is an advantage that the action due to the uneven opening area of the recess 8 can be obtained appropriately.
- the number Nc of the recessed portions 8 in the central region CR in the tire width direction and the number Ne of the recessed portions 8 in the end region in the tire width direction have a relationship Ne ⁇ Nc. (See FIGS. 3, 6 and 7).
- the recesses 8 are densely arranged in the center region CR in the tire width direction, the contact area of the center region CR is reduced, the contact pressure is increased, and a snow column shear force (so-called so-called) Increases digging power.
- the recesses 8 are sparsely arranged in the end region, the ground contact area of the end region of the block 5 is ensured. As a result, there is an advantage that the adhesion action of the end region to the ice road surface is ensured, and the performance of the tire on ice is ensured.
- the number Nc of the recessed portions 8 in the central region CR in the tire width direction and the number Ne of the recessed portions 8 in the end region in the tire width direction are 1.50 ⁇ Nc / Ne. (See FIGS. 3, 6 and 7).
- the arrangement density Da of the recesses 8 in the entire area of the one continuous contact surface is 0.8 [pieces / cm ⁇ 2] ⁇ Da ⁇ 4.0 [pieces / cm ⁇ 2]. It is in the range.
- the arrangement density of the recessed part 8 is optimized. That is, when 0.8 [pieces / cm ⁇ 2] ⁇ Da, the number of the recessed portions 8 is ensured, and the water film removing action is appropriately secured in the recessed portions 8. Further, since Da ⁇ 4.0 [pieces / cm 2], the ground contact areas of the land portions 31 to 33 are appropriately secured.
- the land portions 31 to 33 are provided with a plurality of sipes 6 on the ground contact surface, and the recesses 8 are arranged apart from the sipes 6 (see, for example, FIG. 3).
- the concave portion 8 and the sipe 6 are arranged separately from each other, there is an advantage that the braking performance on ice and the performance on snow of the tire are improved.
- a plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the land portions 31 to 33 into a plurality of sections.
- at least one of any pair of adjacent sections has a recess 8 in the central region CR in the tire width direction (see FIGS. 3 and 7).
- the recessed part 8 is arrange
- a plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the land portions 31 to 33 into a plurality of sections.
- the three adjacent sections include the section having the recess 8 in the center region CR in the tire width direction and the section having the recess 8 in the end region in the tire width direction (for example, FIG. 3). And FIG. 6).
- a plurality of sipes 6 are arranged in parallel in the tire circumferential direction to partition the land portions 31 to 33 into a plurality of sections.
- any three of the sections adjacent in the tire circumferential direction include a section having a recess 8 and the section having no recess 8 (see FIG. 7).
- the recesses 8 are dispersedly arranged by arranging the sections not having the recesses 8.
- the land portions 31 to 33 are block rows having a plurality of blocks 5, and have recesses 8 at the corners of the blocks 5 (see FIGS. 3, 6 and 7).
- the concave portion 8 is disposed at the corner of the block 5 where the ground pressure is high and a water film is likely to be generated. Accordingly, there is an advantage that the water film on the tread is efficiently absorbed on the icy road surface and the braking performance on ice of the tire is improved.
- the ground contact pressure at the corners is further increased by the recesses 8 on the snow road surface, and there is an advantage that the on-snow performance of the tire is improved by increasing the shear force in the snow.
- the land portions 31 to 33 are block rows having a plurality of blocks 5, and the recesses 8 are provided in the end portions of the blocks 5 in the tire circumferential direction and in the central region CR in the tire width direction. Not provided (see FIGS. 3, 6 and 7). Accordingly, there is an advantage that the contact area and rigidity of the end portions on the stepping-in side and the kicking-out side of the block are ensured, and the braking performance on ice and the performance on snow are improved.
- the opening area of the recess 8 is in the range of 2.5 [mm ⁇ 2] to 10 [mm ⁇ 2].
- the opening area of the recessed part 8 is optimized. That is, when the opening area of the recess 8 is 2.5 [mm ⁇ 2] or more, the edge action and water absorption of the recess 8 are ensured. Further, since the opening area of the recess 8 is 10 [mm ⁇ 2] or less, the ground contact area and the rigidity of the land portions 31 to 33 are ensured.
- the recess 8 has a circular shape (see FIG. 4) or an elliptical shape (not shown) on the ground contact surfaces of the land portions 31 to 33. Accordingly, there is an advantage that uneven wear of the ground contact surfaces of the land portions 31 to 33 can be suppressed as compared with the configuration in which the concave portion 8 has a polygonal shape (not shown).
- the wall angle ⁇ of the recess 8 is in the range of ⁇ 85 [deg] ⁇ ⁇ ⁇ 95 [deg] (see FIG. 5).
- the depth Hd of the recess 8 and the groove depth Hg of the thin shallow groove 7 have a relationship of 0.5 ⁇ Hd / Hg ⁇ 1.5 (see FIG. 5).
- the depth Hd of the recessed part 8 is optimized. That is, when 0.5 ⁇ Hd / Hg, the water absorbing action of the recess 8 is ensured.
- Hd / Hg ⁇ 1.5 it is possible to suppress a decrease in rigidity of the land portions 31 to 33 due to the recess 8 being too deep with respect to the thin shallow groove 7.
- the recesses 8 is arranged at a position corresponding to a vent hole (not shown) of the tire molding die.
- the average value Ac of the opening area of the recess 8 in the central region CR in the tire width direction and the average value Ae of the opening area of the recess 8 in the end region in the tire width direction are Ae. ⁇ Ac relationship (see FIGS. 25 to 28).
- the concave portion 8 having a relatively large opening area is disposed in the central region CR, the ground contact area of the central region CR decreases, the ground pressure increases, and the snow column shear force ( The so-called digging force increases. Thereby, the traction performance of the tire is improved, and the performance on snow of the tire is improved.
- the recessed part 8 which has a comparatively small opening area is arrange
- the average value Ac of the opening area of the recess 8 in the central region CR in the tire width direction and the average value Ae of the opening area of the recess 8 in the end region in the tire width direction are 1 .5 ⁇ Ac / Ae ⁇ 4.0.
- the land portions 31 to 33 are provided with a plurality of types of recesses 8 having different opening areas, and 70% or more disposed in the central region CR in the tire width direction.
- the recess 8 has an opening area larger than the average value of the opening areas of the recesses 8 disposed on the continuous ground plane (see FIGS. 26 to 28).
- the land portions 31 to 33 have a plurality of types of recesses 8 having different opening areas, and the average value of the opening areas of the recesses 8 arranged on the continuous ground contact surface.
- the concave portion 8 having a small opening area is arranged on the outermost side in the tire width direction on the continuous contact surface (see FIGS. 26 to 28).
- the land portions 31 to 33 have mutually different opening areas with the plurality of sipes 6 that are arranged in parallel in the tire circumferential direction and divide the land portions 31 to 33 into a plurality of sections.
- a plurality of types of recesses 8 are provided (see FIGS. 26 to 28).
- the recessed part 8 which has an opening area larger than the average value of the opening area of the recessed part 8 arrange
- the land portions 31 to 33 are block rows having a plurality of blocks 5, and are provided with a plurality of types of recesses 8 having mutually different opening areas (see FIGS. 26 to 28). . Further, the recesses 8 having an opening area smaller than the average value of the opening areas of the recesses 8 arranged on the continuous ground surface are arranged at the corners of the block 5. Thereby, the ground contact area of the edge part area
- the pneumatic tire 1 includes land portions 31 to 33 having a plurality of blocks 5 on the tread surface (see FIG. 2).
- the land portions 31 to 33 include a plurality of shallow grooves 7 and a plurality of recesses 8 on the ground contact surface (see FIG. 4). Further, when the region of the central portion 50 [%] in the tire circumferential direction of the continuous ground contact surface is defined as the central region, and the region of the end portion 25 [%] in the tire circumferential direction is defined as the end region.
- the opening area ratio Sc ′ of the recess 8 in the central region CR ′ in the tire circumferential direction of one continuous ground contact surface and the opening area ratio Se ′ of the recess 8 in the end region in the tire circumferential direction are represented by Se ′ ⁇ It has a relationship of Sc ′ (see FIGS. 22 to 24).
- the opening area ratio of the recess 8 is set to be small in the central region CR in the tire circumferential direction, the ground contact area in the central region of the land portions 31 to 33 is ensured, and the braking performance of the tire on ice is improved. There is an advantage to improve. Further, (4) since the concave portion 8 is shallower than a sipe (for example, a linear sipe 6 or a circular sipe (not shown)), the rigidity of the land portions 31 to 33 is appropriately ensured. Thereby, there exists an advantage by which the braking performance on ice of a tire is ensured.
- the number Nc ′ of the recessed portions 8 in the central region CR ′ in the tire circumferential direction and the number Ne ′ of the recessed portions 8 in the end region in the tire circumferential direction are Ne ′ ⁇ Nc. '(See FIGS. 22 to 24).
- the recesses 8 are densely arranged in the center region CR ′ in the tire circumferential direction, the contact area of the center region CR ′ decreases, the contact pressure increases, and the snow column shear force by the recess 8 increases. (So-called digging force) increases.
- the recesses 8 are sparsely arranged in the end region, the ground contact area of the end region of the block 5 is ensured. As a result, there is an advantage that the adhesion of the end region to the ice road surface is ensured and the performance on ice of the tire is ensured.
- the average value Ac ′ of the opening area of the recess 8 in the central region CR ′ in the tire circumferential direction and the average value Ae ′ of the opening area of the recess 8 in the end region in the tire circumferential direction However, Ae ′ ⁇ Ac ′ (see FIGS. 22 to 24).
- the recess 8 having a relatively large opening area is disposed in the central region CR ′ of the block 5 having a low ground pressure. Then, the contact area of the central region CR ′ decreases, the contact pressure increases, and the snow column shearing force (so-called digging force) by the recess 8 increases.
- FIG. 32 is a chart showing a result 1 of the performance test of the pneumatic tire according to the embodiment of the present invention.
- FIG. 33 is a chart showing Result 2 of the performance test of the pneumatic tire according to the embodiment of the present invention.
- test tire having a tire size of 195 / 65R15 is assembled to an applicable rim defined by JATMA, and an air pressure of 230 [kPa] and a maximum load defined by JATMA 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.
- FF Front engine Front drive
- the test vehicle travels on the snow road surface of the snow road test site, and the driving performance and the braking distance from the traveling speed of 40 [km / h] are measured. Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation is preferable as the numerical value increases.
- the test tires of Examples 1 to 10 have the configurations of FIGS. 1 and 2, and the blocks 5 of the land portions 31 to 33 have sipes 6, thin shallow grooves 7 and recesses 8, respectively. Further, as shown in FIG. 4, linear thin shallow grooves 7 are arranged in parallel while being inclined in the tire circumferential direction and penetrate the block 5. Further, the groove width and the groove depth of the thin shallow groove 7 are 0.3 [mm]. Moreover, all the recessed parts 8 in a tread surface have the same shape and a fixed opening area. In all the blocks 5, the number Nc of the recessed portions 8 in the central region CR in the tire width direction and the number Ne of the recessed portions 8 in the end region in the tire width direction have a relationship Ne ⁇ Nc. .
- the arrangement density Da and the arrangement number ratio Ne ⁇ Nc of the recesses 8 are average values of all the blocks 5 on the tread surface. Further, the opening area ratio ratio Sc / Se of the recesses 8 is substantially equal to the ratio Nc / Ne of the number of the recesses 8 arranged in each region.
- the test tires of Examples 11 to 21 have the configurations of FIGS. 1 and 25, and the blocks 5 of the land portions 31 to 33 each have a sipe 6, a thin shallow groove 7, and a recess 8. Further, as shown in FIG. 4, linear thin shallow grooves 7 are arranged in parallel while being inclined in the tire circumferential direction and penetrate the block 5. Further, the groove width and the groove depth of the thin shallow groove 7 are 0.3 [mm]. Further, all the blocks 5 on the tread surface are provided with two types and a plurality of concave portions 8 having different opening areas. Moreover, all the recessed parts 8 have the same shape. Further, the recess 8 having a large opening area Ac is disposed in the central region CR (FIGS.
- the recess 8 having a small opening area Ae is disposed in the end region of the block 5.
- the number Nc of the recessed portions 8 in the central region CR and the number Ne of the recessed portions 8 in the end region are substantially the same.
- the opening area ratio ratio Sc / Se of the recesses is substantially equal to the ratio Ac / Ae of the opening areas of the large and small recesses 8.
- the arrangement density Da of the recesses 8 is an average value of all the blocks 5 on the tread surface.
- the block 5 has only the sipe 6 and the thin shallow groove 7 and does not have the concave portion 8.
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Abstract
Description
図1は、この発明の実施の形態にかかる空気入りタイヤを示すタイヤ子午線方向の断面図である。同図は、タイヤ径方向の片側領域の断面図を示している。また、同図は、空気入りタイヤの一例として、乗用車用ラジアルタイヤを示している。
図2は、図1に記載した空気入りタイヤのトレッド面を示す平面図である。同図は、スタッドレスタイヤのトレッドパターンを示している。同図において、タイヤ周方向とは、タイヤ回転軸周りの方向をいう。また、符号Tは、タイヤ接地端である。
図3は、図2に記載した空気入りタイヤの陸部を示す説明図である。同図は、ショルダー陸部33を構成する1つのブロック5の平面図を示している。
図4は、図3に記載したブロックの要部を示す拡大図である。図5は、図4に記載したブロックの接地面のA-A視断面図である。これらの図において、図4は、サイプ6、細浅溝7および凹部8の位置関係を示し、図5は、細浅溝7および凹部8の深さ方向の断面図を示している。
図2および図3に示すように、この空気入りタイヤ1では、すべての陸部31~33が、複数の凹部8を接地面に備える。かかる構成では、タイヤ接地時にて、凹部8が氷路面とトレッド面との間に生ずる水膜を吸い取り、また、凹部8により陸部31~33のエッジ成分が増加して、タイヤの氷上制動性能が向上する。
この空気入りタイヤ1では、連続した接地面にて定義されるタイヤ幅方向の中央部領域CRにおける凹部8の開口面積率Scと、タイヤ幅方向の端部領域における凹部8の開口面積率Seとが、Se<Scの関係を有する。すなわち、タイヤ幅方向の中央部領域CR(図3参照)における凹部8の開口面積率Scが、端部領域よりも大きい。また、凹部8の開口面積率の比Sc/Seが、1.50≦Sc/Seの関係を有することが好ましく、3.00≦Sc/Seの関係を有することがより好ましい。比Sc/Seの上限は、特に限定がないが、凹部8の配置密度や開口面積との関係により制約を受ける。また、すべての凹部8が中央部領域CRに配置された場合(例えば、後述する図7参照)には、Se=0となり、Se<Scの条件が満たされる。
図8~図14は、図4に記載した空気入りタイヤの変形例を示す説明図である。これらの図は、サイプ6、細浅溝7および凹部8の位置関係を示している。
図22~図24は、図2に記載した空気入りタイヤの変形例を示す説明図である。これらの図において、図22は、ショルダー陸部33を構成する1つのブロック5の平面図を示し、図23は、セカンド陸部32を構成する1つのブロック5の平面図を示し、図24は、センター陸部31を構成する1つのブロック5の平面図を示している。
図25~図28は、図2に記載した空気入りタイヤの変形例を示す説明図である。これらの図において、図25は、空気入りタイヤ1のトレッド面の平面図を示している。また、図26は、ショルダー陸部33を構成する1つのブロック5の平面図を示し、図27は、セカンド陸部32を構成する1つのブロック5の平面図を示し、図28は、センター陸部31を構成する1つのブロック5の平面図を示している。
図29~図31は、図25に記載した空気入りタイヤの変形例を示す説明図である。これらの図において、図29は、ショルダー陸部33を構成する1つのブロック5の平面図を示し、図30は、セカンド陸部32を構成する1つのブロック5の平面図を示し、図31は、センター陸部31を構成する1つのブロック5の平面図を示している。
以上説明したように、この空気入りタイヤ1は、リブあるいは複数のブロックを有する陸部31~33をトレッド面に備える(図2および図25参照)。また、陸部31~33が、複数の細浅溝7と、複数の凹部8とを接地面に備える(図3および図4参照)。また、陸部31~33における連続した接地面のタイヤ幅方向の中央部50[%]の領域を中央部領域として定義し、タイヤ幅方向の左右の端部25[%]の領域を端部領域として定義するときに、1つの連続した接地面のタイヤ幅方向の中央部領域CRにおける凹部8の開口面積率Scと、タイヤ幅方向の端部領域における凹部8の開口面積率Seとが、Se<Scの関係を有する。
Claims (25)
- リブあるいは複数のブロックを有する陸部をトレッド面に備える空気入りタイヤにおいて、
前記陸部が、複数の細浅溝と、複数の凹部とを接地面に備え、且つ、
前記陸部における連続した接地面のタイヤ幅方向の中央部50[%]の領域を中央部領域として定義し、タイヤ幅方向の左右の端部25[%]の領域を端部領域として定義するときに、
1つの前記連続した接地面の前記タイヤ幅方向の中央部領域における前記凹部の開口面積率Scと、前記タイヤ幅方向の端部領域における前記凹部の開口面積率Seとが、Se<Scの関係を有することを特徴とする空気入りタイヤ。 - 前記タイヤ幅方向の中央部領域における前記凹部の開口面積率Scと、前記タイヤ幅方向の端部領域における前記凹部の開口面積率Seとが、1.50≦Sc/Seの関係を有する請求項1に記載の空気入りタイヤ。
- 前記タイヤ幅方向の中央部領域における前記凹部の配置数Neと、前記タイヤ幅方向の端部領域における前記凹部の配置数Neとが、Ne<Ncの関係を有する請求項1または2に記載の空気入りタイヤ。
- 前記タイヤ幅方向の中央部領域における前記凹部の配置数Ncと、前記タイヤ幅方向の端部領域における前記凹部の配置数Neとが、1.50≦Nc/Neの関係を有する請求項3に記載の空気入りタイヤ。
- 1つの前記連続した接地面の全域における前記凹部の配置密度Daが、0.8[個/cm^2]≦Da≦4.0[個/cm^2]の範囲にある請求項1~4のいずれか一つに記載の空気入りタイヤ。
- 前記陸部が、複数のサイプを接地面に備え、且つ、前記凹部が、前記サイプから離間して配置される請求項1~5のいずれか一つに記載の空気入りタイヤ。
- 複数のサイプが、タイヤ周方向に並列に配置されて前記陸部を複数の区間に区画し、且つ、隣り合う任意の一対の前記区間の少なくとも一方が、前記タイヤ幅方向の中央部領域に前記凹部を有する請求項1~6のいずれか一つに記載の空気入りタイヤ。
- 複数のサイプが、タイヤ周方向に並列に配置されて前記陸部を複数の区間に区画し、且つ、タイヤ周方向に隣り合う任意の3つの前記区間が、前記タイヤ幅方向の中央部領域に前記凹部を有する前記区間と、前記タイヤ幅方向の端部領域に前記凹部を有する前記区間とをそれぞれ含む請求項1~7のいずれか一つに記載の空気入りタイヤ。
- 複数のサイプが、タイヤ周方向に並列に配置されて前記陸部を複数の区間に区画し、且つ、タイヤ周方向に隣り合う任意の3つの前記区間が、前記凹部を有する前記区間と、前記凹部を有さない前記区間とをそれぞれ含む請求項1~8のいずれか一つに記載の空気入りタイヤ。
- 前記陸部が、複数のブロックを有するブロック列であり、前記ブロックの角部に前記凹部を有する請求項1~9のいずれか一つに記載の空気入りタイヤ。
- 前記陸部が、複数のブロックを有するブロック列であり、前記ブロックのタイヤ周方向の端部かつ前記タイヤ幅方向の中央部領域には前記凹部を有さない請求項1~10のいずれか一つに記載の空気入りタイヤ。
- 前記凹部の開口面積が、2.5[mm^2]以上10[mm^2]以下の範囲にある請求項1~11のいずれか一つに記載の空気入りタイヤ。
- 前記凹部が、前記陸部の接地面にて円形状あるいは楕円形状を有する請求項1~12のいずれか一つに記載の空気入りタイヤ。
- 前記凹部の壁角度αが、-85[deg]≦α≦95[deg]の範囲にある請求項1~13のいずれか一つに記載の空気入りタイヤ。
- 前記凹部の深さHdと、前記細浅溝の溝深さHgとが、0.5≦Hd/Hg≦1.5の関係を有する請求項1~14のいずれか一つに記載の空気入りタイヤ。
- 少なくとも一部の前記凹部が、タイヤ成形金型のベント穴に対応する位置に配置される請求項1~15のいずれか一つに記載の空気入りタイヤ。
- 前記タイヤ幅方向の中央部領域における前記凹部の開口面積の平均値Acと、前記タイヤ幅方向の端部領域における前記凹部の開口面積の平均値Aeとが、Ae<Acの関係を有する請求項1または2に記載の空気入りタイヤ。
- 前記タイヤ幅方向の中央部領域における前記凹部の開口面積の平均値Acと、前記タイヤ幅方向の端部領域における前記凹部の開口面積の平均値Aeとが、1.5≦Ac/Ae≦4.0の関係を有する請求項17に記載の空気入りタイヤ。
- 前記陸部が、相互に異なる開口面積をもつ複数種類の前記凹部を備え、且つ、前記タイヤ幅方向の中央部領域に配置された70[%]以上の前記凹部が、前記連続した接地面に配置された前記凹部の開口面積の平均値よりも大きな開口面積を有する請求項17または18に記載の空気入りタイヤ。
- 前記陸部が、相互に異なる開口面積をもつ複数種類の前記凹部を備え、且つ、前記連続した接地面に配置された前記凹部の開口面積の平均値よりも小さな開口面積をもつ前記凹部が、前記連続した接地面にてタイヤ幅方向の最も外側に配置される請求項17~19のいずれか一つに記載の空気入りタイヤ。
- 前記陸部が、タイヤ周方向に並列に配置されて前記陸部を複数の区間に区画する複数のサイプと、相互に異なる開口面積をもつ複数種類の前記凹部とを備え、且つ、
前記連続した接地面に配置された前記凹部の開口面積の平均値よりも大きな開口面積をもつ前記凹部が、タイヤ周方向に隣り合う任意の3つの前記区間の少なくとも1つに配置される請求項17~20のいずれか一つに記載の空気入りタイヤ。 - 前記陸部が、複数のブロックを有するブロック列であると共に、相互に異なる開口面積をもつ複数種類の前記凹部を備え、且つ、
前記連続した接地面に配置された前記凹部の開口面積の平均値よりも小さな開口面積をもつ前記凹部が、前記ブロックの角部に配置される請求項17~21のいずれか一つに記載の空気入りタイヤ。 - 複数のブロックを有する陸部をトレッド面に備える空気入りタイヤにおいて、
前記陸部が、複数の細浅溝と、複数の凹部とを接地面に備え、且つ、
連続した接地面のタイヤ周方向の中央部50[%]の領域を中央部領域として定義し、タイヤ周方向の前後の端部25[%]の領域を端部領域として定義するときに、
1つの前記連続した接地面の前記タイヤ周方向の中央部領域における前記凹部の開口面積率Sc’と、前記タイヤ周方向の端部領域における前記凹部の開口面積率Se’とが、Se’<Sc’の関係を有することを特徴とする空気入りタイヤ。 - 前記タイヤ周方向の中央部領域における前記凹部の配置数Nc’と、前記タイヤ周方向の端部領域における前記凹部の配置数Ne’とが、Ne’<Nc’の関係を有する請求項23に記載の空気入りタイヤ。
- 前記タイヤ周方向の中央部領域における前記凹部の開口面積の平均値Ac’と、前記タイヤ周方向の端部領域における前記凹部の開口面積の平均値Ae’とが、Ae’<Ac’の関係を有する請求項23または24に記載の空気入りタイヤ。
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