JP2021030765A - tire - Google Patents

Abstract

To provide a tire which can improve operational stability on a snow road surface and a dry road surface.SOLUTION: A tire 1 comprises a tread part 2 partitioned by a first tread end Te1 and a second tread end Te2. The tread part 2 is provided with a plurality of first inclined grooves 3A which extend from the first tread end Te1 toward the second tread end Te2 side with first inclination, and a first sub-groove 7 which extends from each first inclined groove 3A. The first inclined groove 3A has a first inner end 10 which terminates without reaching the second tread end Te2. The first sub-groove 7 communicates with the first inclined groove 3A between the first tread end Te1 and the first inner end 10, and extends to the first tread end Te1 side with second inclination in a direction opposite to the first inclination. The first sub-groove 7 communicates with the first inclined groove 3A via a groove width enlarged part whose groove width is enlarged toward the first inclined groove 3A.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tire including a tread portion.

Patent Document 1 below proposes a pneumatic tire that can be suitably used as a winter tire. The tread portion of the pneumatic tire is provided with an inclined lateral groove, an inner joint groove, and an outer joint groove. The inclined lateral groove extends inward in the tire axial direction from the outside beyond the ground contact end to the inner end near the equator of the tire. On the other hand, the inner joint groove and the outer joint groove have different inclination directions from the inclined lateral grooves, and communicate between the inclined lateral grooves adjacent to each other in the tire circumferential direction.

Japanese Unexamined Patent Publication No. 2016-196288

With the above-mentioned pneumatic tires, there was room for further improvement in steering stability on snowy roads and dry roads.

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire capable of improving steering stability on snowy road surfaces and dry road surfaces.

The present invention is a tire including a tread portion partitioned by a first tread end and a second tread end, and the tread portion has a first tread portion from the first tread end toward the second tread end side. A plurality of first inclined grooves extending with the inclination of the tire and a first auxiliary groove extending from each of the first inclined grooves are provided, and the first inclined groove is a first end without reaching the second tread end. The first sub-groove has an inner end, and the first sub-groove communicates with the first inclined groove between the first tread end and the first inner end, and is in the direction opposite to the first inclination. The first sub-groove extends toward the end side of the first tread with an inclination of 2, and communicates with the first inclined groove via a groove width expanding portion in which the groove width expands toward the first inclined groove. It is characterized by being tired.

In the tire according to the present invention, the groove width expanding portion may have a substantially triangular shape in a plan view.

In the tire according to the present invention, the groove width expansion portion may include an axial edge extending at an angle of ± 10 ° with respect to the tire axial direction.

In the tire according to the present invention, the axial edge may be provided on the first inner end side with respect to the first sub-groove in the tire axial direction.

In the tire according to the present invention, the groove wall of the axial edge may be inclined at an angle of 0 to 60 ° with respect to the radial direction of the tire.

In the tire according to the present invention, the maximum groove width of the groove width expanding portion is the length of the groove width expanding portion measured along the groove center line of the first sub-groove and the width of the first inclined groove. It may be 0.8 to 1.2 times the sum of.

In the tire according to the present invention, the rotation direction of the tread portion is specified, and the first inclined groove is the first-come-first-served side in the rotation direction from the first tread end toward the second tread end side. May be tilted to.

In the tire according to the present invention, the first sub-groove may communicate with the first inclined groove adjacent to each other in the tire circumferential direction.

In the tire according to the present invention, the first inclined groove has a first portion in which the groove width gradually decreases from the first tread end toward the second tread end side, and the second tread end of the first portion. A second portion connected to the side and the groove width gradually increases toward the second tread end side, and a second portion connected to the second tread end side of the second portion and the groove width gradually decreases toward the second tread end side. It may have a third portion of the tire tread.

In the tire according to the present invention, the third portion may be terminated at the first inner end.

In the tire according to the present invention, the third portion may intersect the tire equator.

In the tire according to the present invention, the tread portion has a stud pin in a land portion divided by the first inclined groove, the first sub-groove, and the groove width expanding portion adjacent to each other in the tire circumferential direction. It may have a hole for fixing.

In the tire according to the present invention, the first sub-groove is located on the innermost first sub-groove provided on the first inner end side and on the first tread end side of the first sub-groove. The groove width expanding portion may be provided in the inner first sub-groove, including the outer first sub-groove provided.

In the tire according to the present invention, the first inner end may be provided on the second tread end side of the tire equator.

In the tire according to the present invention, the tread portion includes a plurality of second inclined grooves extending from the second tread end toward the first tread end side at the second inclination, and the second inclined groove. A second sub-groove extending from each is provided, the second inclined groove has a second inner end that terminates without reaching the first tread end, and the second sub-groove has the second tread end. And the second inner end, which communicates with the second inclined groove and extends toward the end side of the second tread at the first inclination, and the second sub-groove extends to the second inclined groove side. It may communicate with the second inclined groove through a groove width expanding portion in which the groove width expands toward the groove.

In the tire according to the present invention, the second inner end is provided on the first tread end side of the tire equator, and the second inner end is the first inclined groove and the first sub-groove. It does not have to be connected.

In the tire of the present invention, two intersecting snow columns can be firmly and integrally formed by the first inclined groove and the first sub-groove. Further, the groove width expanding portion can increase the volume of the portion where the two snow columns intersect. Therefore, since the tire of the present invention can obtain a large snow column shearing force, it is possible to improve the steering stability on a snowy road surface.

The tread portion can suppress a decrease in rigidity of the land portion near the first inner end by the first inclined groove terminated at the first inner end. Further, in the tread portion, the angle formed by the groove edge of the groove width expanding portion and the groove edge of the first inclined groove, and the groove edge of the groove width expanding portion and the groove edge of the first sub-groove are formed. The angle of formation can be increased. As a result, the tread portion can increase the rigidity of the land portion of the portion where the first inclined groove and the first sub-groove communicate with each other. Therefore, the tire of the present invention can improve steering stability on a dry road surface.

It is a development view which shows an example of the tread part of a tire. It is an enlarged view of the contour of the 1st inclined groove and the 1st sub-groove of FIG. It is a partially enlarged view of FIG. It is a perspective view which shows an example of the groove width expansion part. It is a partially enlarged view of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a development view showing an example of the tread portion 2 of the tire 1. In this embodiment, a pneumatic tire for a passenger car is shown as a preferred embodiment. However, it goes without saying that the present invention can be applied to tires for heavy loads such as trucks and buses, and tires of other categories such as airless tires. Further, the tire 1 of the present embodiment is configured as a winter tire, but is not limited to such a mode.

The tire 1 of the present embodiment includes, for example, a directional pattern in which the rotation direction R is specified. The rotation direction R is indicated by characters or symbols on the sidewall portion (not shown), for example. The tire 1 may include a non-directional pattern in which the rotation direction R is not specified, instead of the above-mentioned directional pattern.

The tread portion 2 is partitioned by a first tread end Te1 and a second tread end Te2. The tread portion 2 of the present embodiment includes, for example, a first tread portion 2A between the tire equator C and the first tread end Te1 and a second tread portion 2B between the tire equator C and the second tread end Te2. Includes. The first tread portion 2A and the second tread portion 2B are substantially line-symmetrical except that they are displaced in the tire circumferential direction. Therefore, each configuration of the first tread portion 2A can be applied to the second tread portion 2B.

When the tire 1 is a pneumatic tire, the first tread end Te1 and the second tread end Te2 are the outermost tire axial directions when a normal load is applied to the tire 1 in a normal state and the tire 1 touches the ground at a camber angle of 0 °. The grounding position of.

The normal state is a state in which the tire 1 is rim-assembled on a normal rim (not shown), the normal internal pressure is applied, and there is no load. In the present specification, the dimensions and the like of each part of the tire are values measured in a normal state unless otherwise specified.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, and ETRTO. If there is, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS AT" The maximum value described in "VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum load capacity", for TRA, the table "TIRE LOAD LIMITS" The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

The tread portion 2 is provided with an inclined groove 3 and an auxiliary groove 4. As a result, the tread portion 2 is provided with a land portion 5 which is divided into an inclined groove 3 and a sub groove 4. Further, the tread portion 2 of the present embodiment is provided with a sipe 6. In the present specification, the sipe 6 means a notch having a width of less than 1.5 mm. The tread portion 2 having such a sipe 6 can exert a high frictional force on an ice-snow road.

The inclined groove 3 is configured to include a plurality of first inclined grooves 3A and a plurality of second inclined grooves 3B. The first inclined groove 3A is mainly provided in the first tread portion 2A. On the other hand, the second inclined groove 3B is mainly provided in the second tread portion 2B. The first inclined groove 3A and the second inclined groove 3B of the present embodiment have substantially the same configuration. Therefore, unless otherwise specified, the configuration of the first inclined groove 3A can be applied to the second inclined groove 3B.

The groove width W1 and the depth (not shown) of the inclined groove 3 can be appropriately set according to the tire category. The groove width W1 is set to, for example, 2.0% to 6.0% of the tread width T in the case of a winter tire for a passenger car as in the present embodiment. On the other hand, the depth of the present embodiment is, for example, 6.0 to 12.0 mm, preferably 8.0 to 10.0 mm. The tread width T is the distance in the tire axial direction from the first tread end Te1 to the second tread end Te2 in the normal state.

The sub-groove 4 includes a plurality of first sub-grooves 7 and a plurality of second sub-grooves 8. The first sub-groove 7 is provided in the first tread portion 2A. On the other hand, the second sub-groove 8 is provided in the second tread portion 2B. Since the first sub-groove 7 and the second sub-groove 8 of the present embodiment have substantially the same configuration, the configuration of the first sub-groove 7 is the second sub-groove 8 unless otherwise specified. Can be applied to.

The groove width W2 and the depth (not shown) of the sub-groove 4 can be appropriately set in the same manner as in the inclined groove 3. The groove width W2 is set to, for example, 1.0% to 3.0% of the tread width T. On the other hand, the depth can be set in the same range as the depth of the inclined groove 3 (not shown).

The first inclined groove 3A extends from the first tread end Te1 toward the second tread end Te2 side with a first inclination. In the present embodiment, the first inclination indicates an inclination from the first tread end Te1 toward the second tread end Te2 side toward the first-come-first-served side in the rotation direction R. The first inclination may be an inclination toward the rear arrival side in the rotation direction R. The first inclined groove 3A has a first inner end 10 that terminates without reaching the second tread end Te2.

Such a first inclined groove 3A can form a long snow pillar extending diagonally with respect to the tire axial direction when traveling on a snowy road surface. Therefore, the first inclined groove 3A can obtain a snow column shearing force (traction on snow) in a well-balanced manner in the tire circumferential direction and the tire axial direction by shearing the snow column, so that steering stability on a snowy road surface can be obtained. Can be enhanced.

The first inner end 10 of the present embodiment is provided on the second tread end Te2 side of the tire equator C. As a result, the first inclined groove 3A can form a long snow pillar that exceeds the tire equator C from the first tread end Te1, so that steering stability on a snowy road surface can be effectively improved. The distance L4 in the tire axial direction from the tire equator C to the first inner end 10 can be appropriately set. The distance L4 of this embodiment is set to 1% to 5% of the tread width T.

The tread portion 2 is suppressed from a decrease in rigidity of the land portion 5 near the first inner end 10 by the first inclined groove 3A terminated at the first inner end 10. Further, the first inclined groove 3A of the present embodiment does not intersect with the second inclined groove 3B, but is interrupted in front of the second inclined groove 3B. As a result, the first inclined groove 3A can effectively suppress the decrease in the rigidity of the land portion 5 near the first inner end 10. Therefore, the tire 1 of the present embodiment can improve the steering stability on a dry road surface.

FIG. 2 is an enlarged view of the contours of the first inclined groove 3A and the first sub-groove 7 of FIG. In FIG. 2, the sipe 6 and the hole 48 shown in FIG. 1 are omitted. As shown in FIG. 2, the shortest distance L7 from the first inner end 10 of the first inclined groove 3A to the second inclined groove 3B can be appropriately set. The shortest distance L7 of this embodiment is set to 2 to 6% of the tread width T (shown in FIG. 1).

The first inclined groove 3A of the present embodiment is curved so that, for example, the angle θ4 with respect to the tire axial direction gradually increases toward the tire equator C side. As a result, the first inclined groove 3A can exert a snow column shearing force also in the tire axial direction when traveling on an ice-snow road. The angle θ4 can be set as appropriate. The angle θ4 is preferably set to 5 to 75 °.

The first inclined groove 3A of the present embodiment has a first portion 11, a second portion 12, and a third portion 13.

In the first portion 11, the groove width W1 gradually decreases from the first tread end Te1 toward the second tread end Te2 side. As a result, in the first portion 11, the minimum groove width W1a is formed at the end on the second tread end Te2 side. In such a first portion 11, the rigidity of the land portion 5 (shown in FIG. 1) can be increased toward the tire equator C side on which a large contact pressure acts, so that the steering stability on a dry road surface can be improved. Can be enhanced. Further, since the first portion 11 can form a large snow column toward the outside in the tire axial direction, it is possible to effectively improve the steering stability (turning property) on a snowy road surface. Further, the first portion 11 is also useful for improving the snow removal property in the first inclined groove 3A.

The second portion 12 is continuous with the second tread end Te2 side of the first portion 11, and the groove width W1 thereof gradually increases toward the second tread end Te2 side. Such a second portion 12 can partially expand the groove width W1 in the vicinity of the tire equator C on which a large contact pressure acts. As a result, the volume of the snow column can be increased in the second portion 12, so that a larger snow column shearing force can be expected.

The maximum groove width W1b of the second portion 12 can be appropriately set. The maximum groove width W1b of the present embodiment is set to 1.1 to 2.0 times the minimum groove width W1a of the first portion 11. By setting the maximum groove width W1b to 1.1 times or more the minimum groove width W1a, the volume of the snow column can be increased in the vicinity of the tire equator C. On the other hand, when the maximum groove width W1b is set to 2.0 times or less the minimum groove width W1a, the rigidity of the land portion 5 (shown in FIG. 1) is reduced on the tire equator C side on which a large contact pressure acts. Can be prevented.

The third portion 13 is connected to the second tread end Te2 side of the second portion 12, and the groove width W1 thereof gradually decreases toward the second tread end Te2 side. The third portion 13 of the present embodiment is terminated at the first inner end 10. The third portion 13 of the present embodiment intersects the tire equator C. By connecting the third portion 13 and the second portion 12, the first inner end 10 side of the first inclined groove 3A can be formed in a substantially triangular shape in a plan view. Since such a third portion 13 can suppress a decrease in rigidity of the land portion 5 (shown in FIG. 1) near the first inner end 10 in the vicinity of the tire equator C on which a large contact pressure acts, the snow road surface. And can improve steering stability on dry roads.

The length L5 from the boundary point 15 between the third portion 13 and the second portion 12 to the first inner end 10 and the length from the boundary point 16 between the second portion 12 and the first portion 11 to the first inner end 10 The ratio L5 / L6 to the L6 can be appropriately set. It is assumed that these lengths L5 and L6 are measured along the groove edge e2 on the trailing side of the rotation direction R of the first inclined groove 3A. The ratio L5 / L6 of this embodiment is set to 0.4 to 0.6. As a result, the second portion 12 and the third portion 13 are formed to have substantially the same length, so that the rigidity of the land portion 5 (shown in FIG. 1) is suppressed in the vicinity of the first inner end 10 while being suppressed. The volume of the snow column can be increased.

As shown in FIG. 1, the first sub-groove 7 extends from each of the first inclined grooves 3A. The first sub-groove 7 communicates with the first inclined groove 3A between the first tread end Te1 and the first inner end 10. Such a first sub-groove 7 can form a snow pillar that intersects with a snow pillar formed by the first inclined groove 3A, and these two snow pillars can be formed firmly and integrally. Therefore, since the tire 1 of the present embodiment can obtain a large snow column shearing force, it is possible to improve the steering stability on a snowy road surface.

The first sub-groove 7 has a second inclination opposite to the first inclination and extends toward the first tread end Te1 side. In the present embodiment, the second inclination indicates an inclination from the second tread end Te2 side toward the first tread end Te1 side toward the first-come-first-served side in the rotation direction R. As a result, the first sub-groove 7 can form a snow pillar that is inclined in the opposite direction to the snow pillar formed by the first inclined groove 3A. Therefore, the tire 1 of the present embodiment can obtain a snow column shearing force (traction on snow) in a well-balanced manner in the tire circumferential direction and the tire axial direction by shearing the snow column, so that the steering is stable on a snowy road surface. It can enhance the sex. The angle θ5 of the first sub-groove 7 with respect to the tire circumferential direction can be appropriately set. The angle θ5 (shown in FIG. 2) of this embodiment is set to 10 to 50 °.

The first sub-groove 7 of the present embodiment communicates with the first inclined grooves 3A and 3A adjacent to each other in the tire circumferential direction. As a result, the first sub-groove 7 can form a snow pillar that intersects the two snow pillars formed by the first inclined grooves 3A and 3A, respectively, and these three snow pillars are firmly and integrally integrated. Since it can be formed in, a large snow column shearing force can be obtained. Therefore, the tire 1 of the present embodiment can improve the steering stability on a snowy road surface.

The first sub-groove 7 of the present embodiment includes an inner first sub-groove 7i and an outer first sub-groove 7o. The first sub-groove 7i is provided on the most inner end 10 side (tire equator C side) of the plurality of first sub-grooves 7. On the other hand, the outer first sub-groove 7o is provided on the first tread end Te1 side (outside in the tire axial direction) with respect to the inner first sub-groove 7i. As a result, the land portion 5 is divided between the first inclined grooves 3A and 3A adjacent to each other in the tire circumferential direction by the inner first sub-groove 7i, and the inner first sub-groove 7i and the outer first sub-groove 7i. It includes a middle block 5B divided by a first sub-groove 7o and a shoulder block 5C divided by an outer first sub-groove 7o and a first tread end Te1.

As shown in FIG. 2, the intersection of the back-attached side of the groove center line of the first sub-groove 7i in the rotation direction R and the groove center line of the first inclined groove 3A is defined as the third intersection P3. Further, the intersection of the rear-attached side of the groove center line of the outer first sub-groove 7o in the rotation direction R and the groove center line of the first inclined groove 3A is defined as the fourth intersection P4. In the present embodiment, the angle θ6 between the groove center line of the first sub-groove 7i at the third intersection P3 and the groove center line of the first inclined groove 3A, and the outer first at the fourth intersection P4. The angle θ7 between the groove center line of the sub-groove 7o and the groove center line of the first inclined groove 3A is different from each other. The angle θ6 at the third intersection P3 of the present embodiment is set to, for example, 40 to 60 °. On the other hand, the angle θ7 at the fourth intersection P4 is set to, for example, 60 to 80 °.

The first-come-first-served side of the groove center line C1 (shown in FIG. 3) of the first sub-groove 7i in the rotation direction R and the virtual line 29 of the groove edge e2 on the second-arrival side of the rotation direction R of the first inclined groove 3A. The intersection is defined as the first intersection P1. The intersection of the groove center line of the first inclined groove 3A and the first tread end Te1 is defined as the second intersection P2.

As shown in FIG. 1, the straight line connecting the first intersection P1 and the second intersection P2 is defined as the first straight line 31. The straight line connecting the first intersection P1 and the first inner end 10 is defined as the second straight line 32. The straight line connecting the first intersection P1 and the third intersection P3 is defined as the third straight line 33. It is desirable that the angle θ1 of the first straight line 31 with respect to the tire axial direction, the angle θ2 of the second straight line 32 with respect to the tire axial direction, and the angle θ3 of the third straight line 33 with respect to the tire axial direction satisfy the following relationships.
θ1 <θ2 <θ3

The first sub-groove 7i is different from the first inclined groove 3A because the angle θ3 of the third straight line 33 is set to be larger than the angle θ1 of the first straight line 31 and the angle θ2 of the second straight line 32. It is possible to form a snow column that inclines at an angle, and it is possible to provide a snow column shearing force in a well-balanced manner in the tire circumferential direction and the tire axial direction. In order to effectively exert such an action, the angle θ3 of the third straight line 33 is preferably 120 to 140 °.

By setting the angle θ1 of the first straight line 31 to be smaller than the angle θ2 of the second straight line 32, the first inclined groove 3A is a snow column that inclines slightly with respect to the tire axial direction on the first tread end Te1 side. Can be formed. Therefore, the tire 1 can exhibit traction performance on a snowy road surface. Further, by setting the angle θ2 of the second straight line 32 to be larger than the angle θ1 of the first straight line 31, the first inclined groove 3A is located on the tire equatorial line C on which a large contact pressure acts with respect to the tire axial direction. It is possible to form a snow column that slopes greatly. Therefore, the tire 1 can exhibit excellent traction performance and turning performance on a snowy road surface. In order to effectively exert such an action, the angle θ1 of the first straight line 31 is preferably 15 to 30 °, and the angle θ2 of the second straight line 32 is preferably 45 to 60 °.

Then, the first sub-groove 7 (in this example, the first sub-groove 7i) is via a groove width expanding portion 21 in which the groove width W2 (shown in FIG. 1) expands toward the first inclined groove 3A. , Communicate with the first inclined groove 3A. That is, the first sub-groove 7 of the present embodiment includes a groove width expanding portion 21 and a main portion 22 having a groove width W2 smaller than that of the groove width expanding portion 21. The groove width expanding portion 21 of the present embodiment is provided on the rear-attached side of the first sub-groove 7 (main portion 22) in the rotation direction R. The groove width expanding portion 21 may also be provided in the outer first sub-groove 7o.

The groove width expanding portion 21 can increase the volume of the portion where the two snow columns formed by the first inclined groove 3A and the first sub-groove 7 intersect. Therefore, since the tire 1 of the present embodiment can obtain a large snow column shearing force, it is possible to improve the steering stability on a snowy road surface. Since the groove width expanding portion 21 of the present embodiment is provided in the first sub-groove 7i inside, a large snow column shearing force can be effectively obtained in the vicinity of the tire equator C on which a large contact pressure acts. ..

FIG. 3 is a partially enlarged view of FIG. As shown in FIG. 3, the tread portion 2 includes the groove edge of the groove width expanding portion 21 (in this example, the groove edge on the inner side in the tire axial direction) e4 and the groove edge of the first inclined groove 3A (in this example, rotation). The angle θ8 formed by the first-come-first-served side groove edge in the direction R, the groove edge of the groove width expanding portion 21 (in this example, the groove edge on the inner side in the tire axial direction) e4, and the first sub-groove 7 (main portion 22). ) (In this example, the inner groove edge in the tire axial direction) e6 and the angle θ9 can be increased. As a result, the tread portion 2 can increase the rigidity of the land portion 5 (shown in FIG. 1) at the portion where the first inclined groove 3A and the first sub-groove 7 communicate with each other. Therefore, the tire 1 of the present embodiment can improve steering stability (turning performance) on a dry road surface.

As shown in FIG. 2, the distance L5 from the third intersection P3 where the groove width expanding portion 21 is provided to the tire equator C is the first tread end Te1 (or the second tread end Te2) from the tire equator C. It is desirable to set it to 10% to 20% of the tread half width T1 (shown in FIG. 1) up to. By setting the distance L5 to 20% or less of the tread half width T1, the groove width expanding portion 21 can form a large snow column on the tire equator C side on which a large ground pressure acts. Therefore, the tire 1 of the present embodiment can improve the steering stability on a snowy road surface. Further, by setting the distance L5 to 10% or more of the tread half width T1, the groove width expanding portion 21 is formed outside the tire axial direction with respect to the tire equator C. As a result, the tire 1 of the present embodiment can maintain the rigidity of the land portion 5 arranged on the tire equator C, so that the steering stability on a dry road surface can be improved.

The groove width expanding portion 21 of the present embodiment extends to at least one of the pair of groove edges e3 and e4 forming the groove width expanding portion 21 at an angle of ± 10 ° with respect to the tire axial direction (not shown). Includes the axial edge 24. With such an axial edge 24, the groove width expanding portion 21 can form a snow column extending in the tire axial direction. Therefore, since the groove width expanding portion 21 can obtain a large snow column shearing force, it is possible to effectively improve the steering stability on a snowy road surface.

The axial edge 24 can be provided on any of the pair of groove edges e3 and e4 forming the groove width expanding portion 21. The axial edge 24 of the present embodiment is provided on the first inner end 10 side (in this example, the tire equator C side) with respect to the first sub-groove 7 in the tire axial direction. The axial edge 24 is provided on the groove edge e4 on the inner side in the tire axial direction. As a result, the axial edge 24 can form a snow column extending in the tire axial direction in the vicinity of the first inner end 10 (tire equatorial line C) on which a large contact pressure acts, so that steering stability on a snowy road surface can be formed. Can be effectively enhanced. In order to effectively enhance such an action, the angle of the axial edge 24 (not shown) is preferably ± 5 °, more preferably ± 1 °, with respect to the tire axial direction.

The shortest distance L6 from the third intersection P3 to the axial edge 24 can be appropriately set. The shortest distance L6 of this embodiment is set to 0.1 to 0.5 times the distance L1 between the tire equator C and the outer end of the center land portion 5A shown in FIG. 1 in the tire axial direction. Is desirable. By setting the shortest distance L6 to 0.1 times or more the distance L1 of the center land portion 5A, a large snow column can be formed in the groove width expanding portion 21. On the other hand, by setting the shortest distance L6 to 0.5 times or less of the distance L1 of the center land portion 5A, the rigidity of the land portion 5 can be maintained, so that the steering stability on a dry road surface can be improved. it can.

The length L7 of the axial edge 24 in the tire axial direction can be appropriately set. The length L7 of this embodiment is set to 4% to 6% of the tread width T (shown in FIG. 1). When the length L7 is set to 4% or more of the tread width T, a large snow column can be formed. On the other hand, by setting the length L7 to 6% or less of the tread width T, it is possible to prevent the density of the snow pillars from becoming small.

FIG. 4 is a perspective view showing an example of the groove width expanding portion 21. As shown in FIG. 4, it is desirable that the groove wall 25 of the axial edge 24 is inclined at an angle of 0 to 60 ° (not shown) with respect to the radial direction of the tire. By setting the angle of the groove wall 25 to 60 ° or less, the groove width expanding portion 21 can increase the volume of the snow column. The angle of the groove wall 25 is preferably 0 to 40 °, more preferably 0 to 30 °.

As shown in FIG. 2, it is desirable that the groove width expanding portion 21 is formed in a substantially triangular shape in a plan view. In the present embodiment, the substantially triangular shape in the plan view is the first-come-first-served basis of the pair of groove edges (including the axial edge 24) e3 and e4 forming the groove width expanding portion 21 and the rotation direction R of the first inclined groove 3A. It is specified in the region 28 surrounded by the virtual line 26 of the groove edge e1 on the side and the virtual line 27 extending the axial edge 24 toward the groove edge e3 on the inner side in the tire axial direction. With such a groove width expanding portion 21, the tire 1 can obtain a snow column shearing force (traction on snow) in a well-balanced manner in the tire circumferential direction and the tire axial direction, so that steering stability on a snowy road surface can be effectively achieved. Can be enhanced.

As shown in FIG. 3, the maximum groove width W3 of the groove width expanding portion 21 can be appropriately set. The maximum groove width W3 is measured on the virtual line 26 of the groove edge of the first inclined groove 3A (in this example, the groove edge e1 on the first-come-first-served side in the rotation direction R). The maximum groove width W3 of the present embodiment is the length L7 and the length L7 of the groove width expanding portion 21 measured along the groove center line C1 of the first sub-groove 7 (in this example, the first sub-groove 7i). It is set to 0.8 to 1.2 times the sum (L7 + W4) of the width W4 of the 1 inclined groove 3A. As a result, the groove width expanding portion 21 has the first inclined groove in the direction along the groove center line C1 of the first sub-groove 7 and the direction along the virtual line 26 of the groove edge e1 of the first inclined groove 3A. Together with 3A, snow columns of substantially equal size can be formed. Therefore, the groove width expanding portion 21 can firmly connect the snow pillar formed by the first inclined groove 3A and the snow pillar formed by the first sub-groove 7, so that the steering is stable on a snowy road surface. You can improve your sex.

As shown in FIG. 1, the second inclined groove 3B extends from the second tread end Te2 toward the first tread end Te1 side with a second inclination. The second inclination is as described above. The second inclined groove 3B has a second inner end 35 that terminates without reaching the first tread end Te1. The second inner end 35 is provided on the first tread end Te1 side of the tire equator C. The second inner end 35 is not connected to the first inclined groove 3A and the first sub-groove 7.

As described above, the second inclined groove 3B has substantially the same configuration as the first inclined groove 3A. Therefore, the configuration of the first inclined groove 3A can be applied to the second inclined groove 3B. Therefore, the second inclined groove 3B can exert the same effect as the first inclined groove 3A.

The second sub-groove 8 extends from each of the second inclined grooves 3B. The second sub-groove 8 communicates with the second inclined groove 3B between the second tread end Te2 and the second inner end 35, and extends to the second tread end Te2 side at the first inclination. The first inclination is as described above. Further, the second sub-groove 8 is configured to include an inner second sub-groove 8i and an outer second sub-groove 8o. As shown in FIG. 2, the second sub-groove 8 (in this example, the second sub-groove 8i) has a groove width in which the groove width W2 (shown in FIG. 1) expands toward the second inclined groove 3B. It communicates with the second inclined groove 3B via the enlarged portion 40.

The second sub-groove 8 (in this example, the second sub-groove 8i) and the groove width expanding portion 40 have substantially the same configuration as the first sub-groove 7 and the groove width expanding portion 21. Therefore, the configurations of the first sub-groove 7 and the groove width expanding portion 21 can be applied to the second sub-groove 8 and the groove width expanding portion 40. Therefore, the second sub-groove 8 and the groove width expanding portion 40 can exert the same effect as the first sub-groove 7 and the groove width expanding portion 21.

As shown in FIG. 1, the center land portion 5A of the present embodiment includes, for example, a plurality of first inclined grooves 3A, a first sub-groove 7i communicating between them, and a plurality of second inclined grooves 3B. And the second sub-groove 8i in which they communicate with each other. As a result, the center land portion 5A is provided, for example, on the central portion of the tread portion 2 in the tire axial direction, more specifically on the tire equator C.

The center land portion 5A is not divided by a groove having a groove width larger than that of the sipe 6 by the first inner end 10 of the first inclined groove 3A and the second inner end 35 of the second inclined groove 3B, and one circumference of the tire. It extends continuously over. Such a center land portion 5A can suppress excessive deformation, and thus can improve steering stability on a dry road surface.

FIG. 5 is a partially enlarged view of FIG. It is desirable that the center land portion 5A is provided with, for example, a plurality of center sipes 6A extending in a zigzag shape in the tire axial direction. Due to the edge of such a center sipe 6A, a large frictional force can be exerted on an ice-snow road and the traction performance can be improved. It is desirable that each center sipe 6A includes, for example, a fully open sipe whose ends communicate with either groove. Such a center sipe 6A can further increase the frictional force on icy and snowy roads.

A first convex portion 41 and a second convex portion 42 are formed on the center land portion 5A. The first convex portion 41 is convex toward the outer side in the tire axial direction with respect to the tire equator C. The first convex portion 41 is a tire of a groove edge e2 on the rear attachment side of the rotation direction R of the first inclined groove 3A and the second inclined groove 3B, and the inner first sub-groove 7i and the inner second sub-groove 8i. It is composed of a groove edge e6 on the inner side in the axial direction. On the other hand, the second convex portion 42 is convex toward the rear arrival side in the rotation direction R. The second convex portion 42 includes a groove edge e1 on the first-come-first-served side of the first inclined groove 3A and the second inclined groove 3B in the rotation direction R, and a tire shaft of the first sub-groove 7i and the inner second sub-groove 8i. It is composed of a groove edge e6 on the inner side in the direction and a groove edge e4 on the inner side in the tire axial direction of the groove width expanding portions 21 and 40. Since the first convex portion 41 and the second convex portion 42 can form edges in the tire circumferential direction and the tire axial direction, they can exert a large frictional force on ice and snow roads and improve traction performance.

A plurality of middle blocks 5B are arranged in the tire circumferential direction. It is desirable that the middle block 5B is provided with, for example, a lug groove 43. One end of the lug groove 43 is connected to, for example, the first inclined groove 3A and the second inclined groove 3B on the rear attachment side of the rotation direction R of the middle block 5B. Further, the other end of the lug groove 43 is interrupted in the middle block 5B. Such a lug groove 43 can suppress a decrease in rigidity of the middle block 5B. Therefore, the lug groove 43 can improve the steering stability on a snowy road surface while maintaining the steering stability on a dry road surface.

It is desirable that the lug groove 43 is formed so as to be smoothly continuous with the inner first sub-groove 7i or the inner second sub-groove 8i via, for example, the first inclined groove 3A or the second inclined groove 3B. .. “Smoothly continuous” means that when the inner first sub-groove 7i or the inner second sub-groove 8i is extended in the length direction thereof, the first inclined groove 3A or the second inclined groove 3B of the lug groove 43 is used. Includes aspects that intersect with at least a portion of the side end.

It is desirable that the lug groove 43 is inclined in the same direction as the inner first sub-groove 7i or the inner second sub-groove 8i, for example. Such a lug groove 43 promotes deformation of the middle block 5B, and eventually causes snow clogging in the first inclined groove 3A, the second inclined groove 3B, the first sub-groove 7i in the inner second sub-groove 8i, and the inner second sub-groove 8i. It can be suppressed. The tire axial angle θ13 of the lug groove 43 is the tire axial angle of the first sub-groove 7i and the inner second sub-groove 8i (that is, the angle θ13 of the third straight line 33 shown in FIG. 1 with respect to the tire axial direction. It is desirable that the angle is set within the same range as θ3).

It is desirable that the middle block 5B is provided with, for example, a plurality of middle sipes 6B. The middle sipe 6B of the present embodiment extends in a zigzag shape, for example. The middle sipe 6B extends in a different direction from, for example, the center sipe 6A. The middle sipe 6B of the present embodiment is inclined in the same direction as, for example, the inner first sub-groove 7i or the inner second sub-groove 8i. Such a middle sipe 6B can enhance traction and turning performance on icy and snowy roads.

The middle block 5B has a groove edge e1 on the first-come-first-served side of the first inclined groove 3A or the second inclined groove 3B in the rotation direction R, and the outer first sub-groove 7o or the outer second sub-groove 8o inside in the tire axial direction. It is desirable that the chamfered portion 46 is provided on the convex portion formed by the groove edge e8 of the above. Such a chamfered portion 46 suppresses damage to the middle block 5B on a dry road surface.

A plurality of shoulder blocks 5C are arranged in the tire circumferential direction. It is desirable that the shoulder block 5C is provided with, for example, a plurality of shoulder sipes 6C. The shoulder sipe 6C of the present embodiment includes a first shoulder sipe 37 and a second shoulder sipe 38 arranged on the outer side of the first shoulder sipe 37 in the tire axial direction. The first shoulder sipe 37 and the second shoulder sipe 38 of the present embodiment extend in a zigzag shape, for example.

The first shoulder sipe 37 extends in a direction different from that of, for example, the center sipe 6A and the middle sipe 6B. The first shoulder sipe 37 of the present embodiment is inclined in the opposite direction to, for example, the middle sipe 6B, and extends along the first inclined groove 3A or the second inclined groove 3B. The first shoulder sipe 37 has a semi-open sipe having one end connected to the outer first sub-groove 7o or the outer second sub-groove 8o and the other end being interrupted in the shoulder block 5C, and both ends being interrupted in the shoulder block 5C. Includes closed cicadas. Such a first shoulder sipe 37 can improve the performance on an ice-snow road and the steering stability on a dry road surface in a well-balanced manner.

The second shoulder sipe 38 extends, for example, along the tire circumferential direction. The second shoulder sipe 38 of the present embodiment is, for example, a closed sipe whose both ends are interrupted in the shoulder block 5C. Such a second shoulder sipe 38 is useful for enhancing one-dancing performance on icy and snowy roads.

As shown in FIG. 1, in the present embodiment, the distance L1 between the tire equatorial line C and the outer end of the center land portion 5A in the tire axial direction, the outer end of the center land portion 5A and the tire axial direction of the middle block 5B The distance L2 between the outer end and the outer end of the middle block 5B and the outer end of the shoulder block 5C in the tire axial direction satisfy the following relationship.
L1 <L2 <L3

When the distances L1, L2, and L3 satisfy the above relationship, the rigidity of the middle block 5B in the tire axial direction can be made higher than the rigidity of the center land portion 5A in the tire axial direction. Further, the rigidity of the shoulder block 5C in the tire axial direction can be made higher than the rigidity of the middle block 5B in the tire axial direction. As described above, the tire 1 of the present embodiment can gradually increase the rigidity in the tire axial direction from the center land portion 5A toward the shoulder block 5C, so that the turning performance on a dry road surface and a snowy road surface can be improved. it can. In order to effectively exert the above action, the distance L2 is preferably 1.05 to 1.2 times the distance L1. The distance L3 is preferably 1.3 to 1.5 times the distance L1.

The tread portion 2 may be provided with a hole 48 for fixing a stud pin (not shown). By fixing the stud pin to such a hole 48, the tire 1 can be configured as a stud tire. Such a tire 1 can improve steering stability especially on an icy road.

As shown in FIG. 5, the hole 48 can be appropriately provided in the land portion 5 (in this example, the center land portion 5A, the middle block 5B, and the shoulder block 5C). In the present embodiment, the first inclined groove 3A (second inclined groove 3B), the first sub-groove 7 (second sub-groove 8), and the groove width expanding portion 21 (groove width expanding portion 40) adjacent to each other in the tire circumferential direction are provided. ), At least one hole 48 is provided in the land portion 5 (in this example, the center land portion 5A). As described above, since the rigidity of the land portion 5 (in this example, the center land portion 5A) is increased by the groove width expanding portion 21, the stud pin (not shown) is used in the tire equator C on which a large contact pressure acts. Retention can be increased. Therefore, the tire 1 can effectively improve the steering stability on an icy road.

As shown in FIG. 1, the land ratio Lr of the tread portion 2 of the present embodiment is preferably, for example, 60% to 80%. As a result, steering stability on snowy roads and dry roads is improved in a well-balanced manner. In the present specification, the “land ratio” is the ratio Sb / Sa of the actual total ground contact area Sb to the total area Sa of the virtual ground contact patch in which each groove and sipe are completely filled.

From the same viewpoint, the rubber hardness Ht of the tread rubber forming the tread portion 2 is preferably, for example, 45 to 60 °, and more preferably 50 to 56 °. In the present specification, "rubber hardness" is the hardness according to durometer type A in an environment of 23 ° C. in accordance with JIS-K6253.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments.

A tire having the basic tread pattern shown in FIG. 1 was prototyped based on the specifications shown in Table 1 (Examples 1 to 12). Further, as a comparative example, a tire provided with a first sub-groove communicating with the first inclined groove without passing through the groove width expanding portion was prototyped. Then, for these tires, the steering stability on snowy roads and dry roads and the holding performance of stud pins were evaluated. The common specifications of each tire are as follows.
Tire size: 205 / 55R16
Rim size: 16 x 6.5
Tire mounting position: All wheels Tire internal pressure:
Front wheel: 240kPa
Rear wheel: 240kPa
Test vehicle: FF vehicle (displacement 2000cc)
Rubber hardness of tread rubber: 56 °
Land ratio: 62%
Tread width T: 173mm
Distance of center land L1: 25.2mm
Groove depth of inclined groove and auxiliary groove: 8.9 mm

<Maneuvering stability on dry roads>
In the test vehicle equipped with the test tires under the above conditions, the characteristics related to handling when traveling on a circuit course on a dry road surface were evaluated by the driver's sensuality by the 10-point method. As a result, the larger the value, the better the steering stability on a dry road surface.

<Maneuvering stability on snowy roads>
In the test vehicle equipped with the test tires under the above conditions, the characteristics related to handling when traveling on a snowy road were evaluated by the driver's sensuality by the 10-point method. As a result, the larger the value, the better the steering stability on a snowy road surface.

<Stud pin holding performance>
After mounting the test tire with the stud pins fixed on the above test vehicle under the above conditions and traveling a predetermined distance, the number of stud pins that fell off from the center land of the test tire was measured. It was evaluated by the 10-point method. As a result, the larger the value, the better the holding performance of the stud pin.
The test results are shown in Tables 1 and 2.

As a result of the test, the tire of the example was able to improve the steering stability on the snowy road surface and the dry road surface as compared with the tire of the comparative example.

2 Tread portion 3A 1st inclined groove 7 1st sub-groove 10 1st inner end 21 Groove width expansion portion Te1 1st tread end Te2 2nd tread end

Claims (16)

A tire having a tread portion partitioned by a first tread end and a second tread end.
The tread portion includes a plurality of first inclined grooves extending from the first tread end toward the second tread end side with a first inclination, and first sub-grooves extending from each of the first inclined grooves. Provided,
The first inclined groove has a first inner end that terminates without reaching the second tread end.
The first sub-groove communicates with the first inclined groove between the first tread end and the first inner end, and has the second inclination opposite to the first inclination. 1 extends to the end of the tread
The first sub-groove communicates with the first inclined groove through a groove width expanding portion in which the groove width expands toward the first inclined groove.
tire. The tire according to claim 1, wherein the groove width expanding portion has a substantially triangular shape in a plan view. The tire according to claim 1 or 2, wherein the groove width expanding portion includes an axial edge extending at an angle of ± 10 ° with respect to the tire axial direction. The tire according to claim 3, wherein the axial edge is provided on the first inner end side with respect to the first sub-groove in the tire axial direction. The tire according to claim 3 or 4, wherein the groove wall of the axial edge is inclined at an angle of 0 to 60 ° with respect to the radial direction of the tire. The maximum groove width of the groove width expanding portion is 0.8 to 1 of the sum of the length of the groove width expanding portion measured along the groove center line of the first sub-groove and the width of the first inclined groove. The tire according to any one of claims 1 to 5, which is twice as much. The direction of rotation of the tread portion is specified, and the tread portion has a designated rotation direction.
The tire according to any one of claims 1 to 6, wherein the first inclined groove is inclined from the first tread end toward the second tread end side toward the first-come-first-served side in the rotational direction. The tire according to any one of claims 1 to 7, wherein the first sub-groove communicates with the first inclined groove adjacent to each other in the tire circumferential direction. The first inclined groove includes a first portion in which the groove width gradually decreases from the first tread end toward the second tread end side.
A second portion of the first portion that is continuous with the second tread end side and whose groove width gradually increases toward the second tread end side.
The tire according to any one of claims 1 to 8, further comprising a third portion of the second portion that is continuous with the second tread end side and whose groove width gradually decreases toward the second tread end side. The tire according to claim 9, wherein the third portion is terminated at the first inner end. The tire according to claim 9 or 10, wherein the third portion intersects the tire equator. The tread portion has a hole for fixing a stud pin in a land portion divided by the first inclined groove, the first sub-groove, and the groove width expanding portion adjacent to each other in the tire circumferential direction. The tire according to any one of claims 1 to 11. The first sub-groove includes an inner first sub-groove provided on the first inner end side and an outer first sub-groove provided on the first tread end side of the inner first sub-groove. Including grooves
The tire according to any one of claims 1 to 12, wherein the groove width expanding portion is provided in the first sub-groove. The tire according to any one of claims 1 to 13, wherein the first inner end is provided on the second tread end side of the tire equator. The tread portion includes a plurality of second inclined grooves extending from the second tread end toward the first tread end side at the second inclination, and second auxiliary grooves extending from each of the second inclined grooves. Is provided,
The second inclined groove has a second inner end that terminates without reaching the first tread end.
The second sub-groove communicates with the second inclined groove between the second tread end and the second inner end, and extends toward the second tread end side at the first inclination. ,
The second sub-groove according to any one of claims 1 to 14, wherein the second sub-groove communicates with the second inclined groove through a groove width expanding portion in which the groove width expands toward the second inclined groove. tire. The second inner end is provided on the first tread end side of the tire equator.
The tire according to claim 15, wherein the second inner end is not connected to the first inclined groove and the first sub-groove.

Images