JP6318018B2 - tire - Google Patents

Description

  The present invention relates to a tire excellent in snow grip performance and wet grip performance.

Conventionally, in order to improve steering stability performance on the WET road surface, drainage grooves (lug grooves) that are curved toward the outer side in the tire width direction and inclined to the opposite side of the rotation direction are provided on both sides of the tire equatorial plane, and the lugs A tread pattern provided with sub-grooves extending in the tire circumferential direction from the grooves is used (for example, Patent Document 1).
In Patent Document 1, the inclination angle of the lug groove as the drainage groove with respect to the tire circumferential direction is 0 ° to 45 ° on the center side of the tread that is the stepped side end, and the tread end that is the end portion on the kicking side. Inclination with respect to the tire circumferential direction is set to 65 ° to 90 ° on the portion side, the end portion on the kicking side opens into the lug groove, and the end portion on the stepping side terminates in the land portion defined by the lug groove. A sub-groove whose angle is smaller than the inclination angle of the lug groove is provided to improve drainage efficiency.

JP 2010-215078 A

  However, since the sub-groove of Patent Document 1 is smaller than the inclination angle, the wet grip performance is improved, but the on-snow grip performance is lowered.

  The present invention has been made in view of the conventional problems, and an object of the present invention is to provide a tire that can improve the grip performance on snow while maintaining the wet grip performance.

The present invention includes a plurality of lug grooves that extend from the equatorial plane on the tread side of the tire tread toward the outer side in the tire width direction on the kick side, and the inclination angle with respect to the tire circumferential direction changes in the tire circumferential direction, and the inclined lug grooves The inclined lug groove is branched from the groove wall of the land portion and terminates in the land portion, and the inclination angle is at a branch point with the inclined lug groove. The sub-groove is equal to the inclination of the tangent line of the inclined lug groove and the end portion is located on the inner side in the tire width direction from the branch point, and the start end portion and the end portion are the center of the opening of the sub-groove. The length of the sub-groove, which is the distance, is the distance between the start end and the point where the straight line passing through the start end and the end portion intersects the land portion. 50% or more and 70% or less, and the groove width of the sub-groove , The inclined lug grooves wherein 1/5 or more of the groove width at the branch point, and wherein the 1/3 or less der Rukoto.
Such sub-grooves not only improve drainage performance, but also can increase the amount of snow penetration due to block collapse in the front-rear direction during driving on snow, thus improving traction performance on snow. Therefore, it is possible to improve the snow grip performance and wet grip performance together.
Strictly speaking, the “branch point” is a point on the outer side in the tire width direction of the opening of the sub-groove, and as shown in FIG. 4A, the stepping side is the lower side and the kicking side is the upper side. When the width direction is set to the lower side, the sub-groove 16A branches from the groove wall on the stepping side of the land portion 14 and terminates in the land portion 14 at a portion protruding upward from the inclined lug groove 13 as shown in FIG. As shown in (b), the portion protruding downward is branched from the groove wall on the kick-out side of the land portion 14 and ends in the land portion 14.
Further, as shown in FIG. 4 (c), when the portion where the inclination angle of the inclined lug groove 13 changes is a broken line portion composed of two line segments m and n having different inclinations, The starting point K of the line segment n becomes the “branch point”, and the slope of the line segment n becomes the slope of the tangent line. Even when the portion where the inclination angle of the inclined lug groove 13 is changed is a portion obtained by connecting two line segments having different inclinations with a curve, the start point of the line segment on the outer side in the tire width direction becomes a “branch point”. The slope of the minute becomes the slope of the tangent.
The inclination angle of the secondary groove is “equal to the inclination of the tangential line of the lug groove at the branch point with the lug groove” only when the inclination angle of the secondary groove 16 matches the inclination of the tangential line of the inclined lug groove 13. This means that the angle difference Δθ is 15 ° or less (| Δθ | ≦ 15 °).

In addition, if the groove depth of the sub-groove is shallower than the groove depth of the inclined lug groove and becomes shallower from the branch point toward the terminal portion, the drainage performance is secured while ensuring block rigidity. Can be improved.
Moreover, since the length of the sub-groove in the tire width direction is 50% or more and 70% or less of the length in the tire width direction of the portion where the sub-groove of the land portion is formed, sufficient drainage performance and A grip on snow can be obtained. Therefore, both the grip performance on snow and the wet grip performance can be improved.
Further, since the groove width of the sub-groove is set to 1/5 or more and 1/3 or less of the groove width of the inclined lug groove, drainage performance and grip force on snow can be obtained with certainty.

  The summary of the invention does not list all necessary features of the present invention, and a sub-combination of these feature groups can also be an invention.

It is a figure which shows the tread pattern of the tire which concerns on this Embodiment. It is a figure which shows the cross-sectional shape of a secondary groove. It is a figure which shows the dimension specification of a subgroove. It is a figure for demonstrating the branch point of a subgroove.

FIG. 1 is a diagram illustrating an example of a tread pattern of a tire 10 according to the present embodiment. The direction from the upper side to the lower side in the figure is the tire rotation direction, the lower side in the figure is the stepping side, and the upper side is the kicking side. Moreover, the left-right direction of the same figure is a tire width direction, CL is an equatorial plane of a tire.
In the figure, 11 is a tread, 12 is a main groove, 13 is an inclined lug groove, 14 is a land portion, 15 is a sipe, and 16 is a sub-groove.
The main groove 12 is a circumferential groove formed at the center in the tire width direction and continuously extending along the tire circumferential direction.
The inclined lug grooves 13 are grooves formed so as to intersect the tire circumferential direction, and are provided on the left and right sides of the equator plane CL, respectively. The right inclined lug groove extends from the lower left to the upper right, the left inclined lug groove extends from the lower right to the upper left, and any of the inclined lug grooves is on the stepping side. It communicates with the main groove 12 and opens at the end in the tire width direction on the kicking side. In this example, the groove width of the main groove 12 is set narrower than the groove width of the inclined lug groove 13.
A land portion 14 is defined by the main groove 12 and the inclined lug grooves 13, 13, and a plurality of sipes 15 are formed on the tire tread side of the land portion 14.
Thus, by providing the sipe 15 in the land portion 14, it is possible to increase the fine edges without reducing the block rigidity and to secure the edge effect during braking and driving.
The extending direction of the sipe 15 is preferably a direction intersecting the tire circumferential direction and the extending direction of the inclined lug groove 13. Further, the shape of the sipe 15 may be a polygonal line shape or a sipe on a wave instead of the straight sipe as shown in FIG. Alternatively, the sipe 15 may be a 3D sipe whose extending direction changes in the tire radial direction.

The sub-groove 16 is a one-side open groove that branches off from the stepping-side groove wall of the land portion 14 and terminates in the land portion 14, and an inclination angle that is an angle formed between the extension direction and the tire circumferential direction is an inclined lug groove 13. Is equal to the inclination of the tangent of the inclined lug groove 13 at the branch point K.
In the inclined lag groove in which the inclination angle increases toward the outer side in the tire width direction as in the inclined lag groove 13 of the present invention, the sub-groove 16 is a portion where the inclination angle of the inclined lag groove 13 is large (inclined lag groove). 13), the amount of snow penetration due to block collapse in the front-rear direction during driving on snow can be increased. That is, by providing the sub-groove 16, it is possible to obtain a shear force in snow during braking and driving on snow, so that grip performance on snow can be ensured.
Further, since the auxiliary groove 16 faces the tangential direction of the inclined lug groove 13, the water on the road surface can be smoothly guided to the inclined lug groove 13. Therefore, both the grip performance on snow and the wet grip performance can be improved.

In this example, as shown in FIG. 2 (a), the average value h of the sub-grooves 16 is made shallower than the groove depth H of the inclined lug grooves 13, and the center of the opening (hereinafter referred to as It is formed so as to become shallower from the start end P) to the end end Q. Specifically, at the start end portion P, the end portion Q coincides with the groove bottom of the inclined lug groove 13 and the end portion Q has a slope of Δh, or the end portion Q as shown in FIG. And a curved shape convex toward the inner side in the tire radial direction.
In this way, if the groove depth of the sub-groove 16 is made shallow at the terminal end Q and the terminal end Q of the sub-groove 16 is raised to the bottom, a decrease in rigidity of the land portion 14 due to the provision of the sub-groove 16 can be suppressed. Sufficient handling stability performance can be secured. Further, since the groove depth on the terminal end portion Q side is made shallow and the groove depth on the start end portion P side is made deep, water in the sub-groove 16 can be smoothly guided to the inclined lug groove.
Further, as shown in FIG. 2C, the cross-sectional shape of the sub-groove 16 may be a slope having a flat portion at the intermediate portion between the start end portion P and the end portion Q. As described above, if the intermediate portion having a constant groove depth is provided, the collapse of the land portion 14 can be further suppressed, so that a decrease in tire rigidity can be reliably suppressed.

Further, in this example, as shown in FIG. 3, the length l of the sub-groove 16 that is the distance between the start end portion P and the end end portion Q is set to the tire width direction of the portion where the sub-groove 16 of the land portion 14 is formed. 50% or more and 70% or less of the length of L ( the distance between the start end portion P and the point indicated by the alternate long and short dash line passing through the start end portion P and the end portion Q ). At the same time, the groove width w of the sub-groove 16 is set to 1/5 or more and 1/3 or less of the groove width W in the vicinity of the branch point K of the inclined lug groove 13.
This is because, when l is less than 50% of L, or when w is less than 1/5 of W, since the volume of the minor groove 16 is small, sufficient drainage performance and on-snow grip force can be obtained. Because there is no. Further, when l exceeds 70% of L, or when w exceeds 1/3 of W, the area of the land portion 14 where the sub-groove 16 is provided becomes small. This is because the rigidity of the portion 14 is lowered.
Therefore, in order to improve both the grip performance on snow and the wet grip performance, it is preferable that 0.5L ≦ l ≦ 0.7L or W / 5 ≦ w ≦ W / 3, and 0.5L ≦ l. More preferably, ≦ 0.7 L and W / 5 ≦ w ≦ W / 3.

  As mentioned above, although this invention was demonstrated using embodiment and an Example, the technical scope of this invention is not limited to the range as described in the said embodiment and Example. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

For example, in the embodiment, one sub-groove 16 is provided in one land portion 14, but it is not necessary to provide the sub-grooves 16 in all land portions 14. A plurality of sub-grooves 16 may be provided in one land portion 14. Needless to say, the number of sub-grooves 16 is appropriately determined according to the tread pattern, such as the degree of change in the inclination angle of the inclined lug groove 13.
Moreover, in the said embodiment, although the inclination lug groove 13 which becomes large as an inclination angle goes to a tire width direction outer side was demonstrated, as for this invention, an inclination angle once becomes small as shown in FIG.4 (b). The present invention can also be applied to an inclined lug groove that becomes larger after a while.
In the case of an inclined lug groove on an arc, the secondary groove 16 can be provided anywhere. However, in order to improve the traction performance on snow, the inclined angle of the inclined lug groove 13 is 60 ° or more. It is preferable to provide the sub-groove 16 in the.

Moreover, although the said embodiment demonstrated the tread pattern which has the circumferential groove | channel (main groove 12) formed in the tire width direction center, you may abbreviate | omit the main groove 12. FIG. That is, since the groove width of the main groove 12 is narrower than the groove width of the inclined lug groove 13, the drainage performance will not be greatly reduced even if the main groove 12 is omitted. Therefore, when priority is given to securing block rigidity, it is preferable to omit the main groove 12.
Conversely, a narrow groove that communicates with the two inclined lug grooves 13 and 13 and extends in a direction close to the tire circumferential direction may be provided. Such a tread pattern is effective when the groove width of the inclined lug groove 13 is narrowed in order to ensure block rigidity.
Moreover, in the said embodiment, although the tire which has a block pattern was demonstrated, it says that this invention is applicable also to the tire etc. which have the rib-shaped land part which continues to the circumferential direction in a tire center part, for example. Not too long.

10 tires, 11 treads, 12 main grooves, 13 inclined lug grooves, 14 land sections,
15 Sipe, 16 Minor groove, CL Equatorial plane.

Claims (2)

A plurality of inclined lug grooves extending from the equatorial plane on the tread side of the tire tread toward the outer side in the tire width direction on the kicking side, the inclination angle with respect to the tire circumferential direction changing in the tire circumferential direction, and the inclined lug grooves Tire with a land portion,
The inclined lug groove is branched from the groove wall of the land portion and ends in the land portion, the inclination angle is equal to the inclination of the tangent line of the inclined lug groove at the branch point with the inclined lug groove, and the terminal portion Has a minor groove on the inner side in the tire width direction than the branch point ,
The length of the sub-groove, which is the distance between the starting end and the terminal end that is the center of the opening of the sub-groove, is such that the straight line passing through the starting end and the starting end and the terminal end is the land portion. 50% or more and 70% or less of the length of the portion where the sub-groove is formed, which is the distance from the intersecting point, and
The tire groove width of the sub-groove is less than 1/5 of the groove width at the branch point of the inclined lug grooves, characterized in der Rukoto 1/3 or less. 2. The tire according to claim 1, wherein a groove depth of the sub-groove is shallower than a groove depth of the inclined lug groove, and becomes shallower from the branch point toward the terminal portion .

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