JP2001322406A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of simultaneously achieving both braking and driving performance on wet, icy, and snowy road surfaces at a highly excellent level. SOLUTION: A tread surface part has an arrangement of directional blocks in which one or more center circumferential direction main grooves, inclined main grooves extended in the form of the notch of an arrow from both side end zones, and inclined auxiliary grooves branched from the inclined main grooves close to both side end zones are parted and formed, the inclined main groove has an inclination angle of 30-65 deg. to a tire equatorial surface and a wider groove width than the inclined auxiliary groove at a main groove part on the inner side of the side end zone. The inclined main groove has groove edge step parts at two or more positions in one groove edge of the main groove part ahead of a tire rotation direction, and the groove width of the inclined main groove is enlarged by the groove edge step part in this rotation direction- designated pneumatic tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a winter pneumatic radial tire having a directional block pattern on a tread portion and having a designated rotation direction, and more particularly to traction on ice and snow. The present invention relates to a pneumatic tire having a tread pattern in which braking performance is balanced at a high level and drainage performance is improved.

[0002]

2. Description of the Related Art A typical example of a tread pattern provided in a winter pneumatic tire that exhibits good traction performance and braking performance under different use conditions on ice and on snow is shown in a tread development diagram of FIG.

In FIG. 2, a tread portion 21 of a tread portion is provided.
The circumferential grooves 22, 23 extending straight in the circumferential direction at the width center position, that is, the position on the tire equatorial plane E, and the positions near both side ends Te, and the circumferential direction between the two circumferential grooves 23. And two circumferential grooves 24 extending in a zigzag pattern.
Further, the tread portion 21 is provided with these circumferential grooves 22, 23, 24.
A plurality of lateral grooves 2 communicating between both ends Te via
5 and 26. With these circumferential grooves 22, 23, 24 and the lateral grooves 25, 26, the tread portion 21 has six circumferential block rows.

[0004] Further, this type of tread pattern is characterized in that corresponding block contour figures on both sides sandwiching the tire equatorial plane E are symmetrical with respect to points on the tire equatorial plane E in a tread development view. Each block has a zigzag sipe 27 extending in the horizontal direction and arranged at substantially equal intervals.

[0005]

However, the tire having the tread pattern shown in FIG. 2 or a tread pattern similar thereto has excellent drainability on a wet road surface due to the straight circumferential grooves 22 and 23, The groove edge component in the direction perpendicular to the tire rotation axis, that is, in the front-back direction is reduced, and the performance of braking and driving on ice and snow is inevitably reduced.

That said, the straight circumferential grooves 22, 23
Is replaced with a zigzag circumferential groove 24, the braking / driving performance is improved, but the drainage property is reduced. Drainage on a wet road surface is as important a performance requirement as braking / driving performance, and this replacement also poses a practical problem.

[0007] Accordingly, the invention described in claims 1 to 11 of the present invention is to provide a pneumatic tire that solves the above-mentioned problems, and more specifically, to provide a drainage property on a wet road surface and a snow-on-ice surface. It is an object of the present invention to provide a pneumatic tire capable of achieving both high levels of braking and driving performance at the same time on a road surface.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, the tread portion has at least one main groove extending in the circumferential direction at the center of the width of the tread portion, An inclined main groove which is inclined in an arrow shape from each of both side end regions of the tread portion and extends toward the central circumferential main groove, and an inclined main groove which branches off from the inclined main groove near each of the both end regions of the tread surface portion and faces toward the center of the tread width. And an inclined sub-groove extending in a direction opposite to the direction of the arrow, and the tread portion has an arrangement of a number of directional blocks defined and formed by these two types of main grooves and sub-grooves. In the entering tire, the inclined main groove is such that the main groove portion inside from the tread side portion both side end regions has an inclination angle within a range of 30 to 65 ° with respect to the tire equatorial plane and a groove wider than the groove width of the inclined sub groove. And the inclined main groove has a width in front of the tire rotation direction. Has a groove edge step portion of the at least two places on one of the groove edges of the main groove part, a pneumatic tire characterized by comprising by widening the groove width of the inclined main groove at the groove edge step portion.

According to the invention described in claim 1, claim 2 is provided.
In the tread portion region inside the both end regions, one groove edge of the inclined main groove extends straight inward and outward from the groove edge step portion, and the other groove of the inclined main groove The edge extends linearly over the entire block, and both groove edges of the inclined sub-groove extend in a curved manner.

According to the first and second aspects of the present invention, as in the third aspect of the present invention, the groove edge step portion is located in the central region of the block edge along the inclined main groove.

Further, according to the invention described in claims 1 to 3, as in the invention described in claim 4, the inclined main groove is provided between the adjacent groove edge step portions from the inside of the tread portion to the outside. It has a groove shape in which the facing groove width gradually decreases, and relates to the invention described in claims 1 to 4, and as in the invention described in claim 5, the inclined main grooves in the tread side portion both side end regions are formed with respect to the tire equatorial plane. 80
It has a tilt angle in the range of ９０90 °.

[0012] Further, according to the inventions described in the first to fifth aspects, as in the invention described in the sixth aspect, each of the two side end regions of the tread portion has a width in the range of 5 to 40% of the tread portion width. .

According to the first to sixth aspects of the present invention, as in the seventh aspect of the present invention, the inclined sub-groove is opened in the central circumferential main groove, and the inclined main groove is formed near the center of the tread width. According to the invention as set forth in claims 1 to 7, the inclined sub-groove has an opening in the inclined sub-groove of 10 to 80% of the groove width of the inclined main groove. And with respect to the invention described in claims 1 to 8, as in the invention described in claim 9, the inclined sub-groove has an average within a range of 40 to 85 ° with respect to the tire equatorial plane. It has a tilt angle.

According to the invention described in the first to ninth aspects, as in the invention described in the tenth aspect, the central circumferential main groove has a straight shape, and both edges of the main groove are formed in a tire. It alternates in and out of the equatorial plane alternately and extends substantially in parallel.

According to the invention described in claims 1 to 10, as in the invention described in claim 11, each of the plurality of directional blocks includes a plurality of sipes.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a developed view of a tread of a pneumatic tire according to the present invention. Although not shown, the pneumatic tire (hereinafter referred to as a tire) has a tread portion, a pair of sidewall portions and a pair of bead portions connected to both sides thereof according to a custom, and these portions are embedded in the bead portion. A radial ply carcass that reinforces between the bead cores, and a belt that strengthens the tread portion around the carcass is provided.

In FIG. 1, the tread portion 1 has at least one main groove extending in the circumferential direction on the center of the width of the tread portion 2, that is, on the tire equatorial plane E. In the illustrated example, one main groove (hereinafter referred to as a circumferential main groove) 3 is provided. And an inclined main groove 4 extending from each of both side end regions Re of the tread surface portion 2 toward the circumferential main groove 3, and branching from the inclined main groove 4 near each of the both end regions Re toward the circumferential main groove 3. And an inclined sub-groove 5 extending therefrom. The inclined main grooves 4 are arranged so as to be inclined in an arrow shape on both sides of a tire equatorial plane (hereinafter referred to as an equatorial plane) E, as if in a C-shape. The inclined sub-groove 5 has at least one inclined main groove 4 in the opposite direction to the inclined main groove 4 in the shape of an arrow, as if it were inclined in a C-shape.
Are arranged so as to extend across.

The tread portion 2 includes a plurality of blocks 6, 7, 8 formed by the circumferential main groove 3, the inclined main groove 4 on both sides of the equatorial plane E, and the inclined sub-grooves 5 on both sides of the equatorial plane E. It has on both sides of E. In addition, the large number of blocks 6, 7, 8 are tilted in an arrowhead shape in an arrow-shaped inclined main groove 4, and in a direction opposite to the main groove 4,
With the inclined sub-grooves 5 crossing the main groove 4, the tire has directionality in the circumferential direction of the tread portion 2, so that the tire has a directional tread pattern, and the direction of the arrow shown in the figure is designated as the rotation direction.

Here, the inclined main groove 4 is such that the main groove portion inside the both side end regions Re of the tread portion 2 is 30 to 6 with respect to the equatorial plane E.
It has a tilt angle in the range of 5 °. Also, the inclined main groove 4
Has a wider groove width than the groove width of the inclined sub-groove 5.

Further, at least two inclined main grooves 4 are provided at _one groove edge (step-side groove edge on the ground contact surface) 4e1 in front of the main groove portion in the tire rotation direction X, and two groove edges are shown in the illustrated example. It has a step 4es. The width of the inclined main groove 4 is increased at the groove edge step 4es.

The tire having the directional tread pattern described above has the following effects. That is, (1) Regarding drainage: (a) By arranging the circumferential main groove 3 in the center of the width of the tread portion 2, the most effective drainage effect can be obtained, and (b)
An inclined main groove 4 extending in an arrow shape toward the circumferential main groove 3 is disposed within a range of an inclination angle of 30 to 65 °, and an inclined sub groove 5 is provided.
By making the groove width wider, the water at the center of the width of the tread portion 2 can be efficiently drained toward the side end Te of the tread portion 2, thereby improving the hydroplaning resistance.

(2) On-snow performance: (a) By arranging the circumferential main groove 3 in the center of the width of the tread portion 2, the skid resistance on snow is improved, and (b) the tread portion 2
By arranging the inclined sub-grooves 5 branching off from the inclined main grooves 4 near each of the both side end regions Re, the driving / braking performance on snow is improved by cooperation of the inclined main grooves 4 and the inclined sub-grooves 5, (C)
By arranging the inclined main groove 4 within the range of the inclination angle of 30 to 65 °, the block rigidity is set to an appropriate value, the driving / braking performance is advantageously secured on snow, and (d) at least two grooves. provided an edge step portion 4es in the rotational direction X ahead of the groove edge 4e _1,
Here, by increasing the groove width, when the tread portion 2 penetrates into the snow, the inclined main groove 4 increases the shear resistance of the snow gripped by the snow, thereby increasing the driving force and the braking force on the snow. This improves the performance on snow.

(3) Performance on ice: (a) A cooperative operation of the inclined main groove 4 and the inclined sub-groove 5 ensures a sufficient edge component in the tire traveling direction, thereby improving the driving and braking performance on ice. (B) The inclined main groove 4 is set at the inclination angle 3
By arranging the blocks within the range of 0 to 65 °, the rigidity of the blocks 6, 7, and 8 is increased at an appropriate value, and the driving and braking performance on ice is improved, thereby improving the performance on ice.

If the inclination angle of the inclined main groove 4 is less than 30 °, the effect on the driving force and braking force on snow is reduced.
Neither is possible because the effect on the driving force and the braking force on the ice is reduced due to a decrease in the rigidity of 7, 8. From this viewpoint, the inclination angle of the inclined main groove 4 is preferably in the range of 35 to 55 °.

Hereinafter, details of the tread portion 2 will be described.
At the inner side of the tread portion 2 area than both end regions Re, depression groove edge 4e ₁ of the inclined main groove 4 extends straight inwardly and outwardly from the groove edge step portion 4ES. Further, in the area of the tread surface portion 2 of the same, the other groove edge of the inclined main groove 4 (a kick-out side groove edge on the ground contact surface) 4e ₂
Extends straight over all blocks 6-8. The inclined main groove 4 composed of the straight groove edges 4e ₁ and 4e ₂ reduces the resistance to the flow of water at the time of drainage, and enables smooth drainage. In particular, it is a straight a straight groove edges 4e ₂ as a kicking side of the ground plane over the entire block 6-8 helps resistance reduction of the flow of water during draining.

On the other hand, both groove edges of the inclined sub-groove 5 are curved. That is, the inclination angle of the inclined sub-groove 5 with respect to the equatorial plane E is reduced near the equatorial plane E and increased near the both end regions Re. As a result, the tread portion 2 of the tire that rolls under a load is in contact with the tread side contact shape and the inclined sub-groove 5.
Can be avoided, and pattern noise peculiar to the block pattern can be reduced.

The groove edge step 4es is located in the central region of the edge of the blocks 7, 8 along the inclined main groove 4. Accordingly, the groove edge step portion 4es can be prevented from triggering the occurrence of uneven wear of the blocks 7 and 8, and the disadvantage of uneven wear resistance does not occur.

Further, the inclined main groove 4 is formed with the adjacent groove edge step portion 4.
Between the es, the groove width gradually decreases from the inside of the tread portion 2 to the outside, in other words, from the equatorial plane E to both side ends Te. As a result, the force for gripping the snow can be increased, which contributes to the driving force and the braking force on the snow.

The inclined main groove 4 in the both end regions Re of the tread portion 2 has an inclination angle in the range of 80 to 90 ° with respect to the equatorial plane E. This contributes to the improvement of the driving force and the braking force on ice and snow, and also has the effect of preventing uneven wear in both side end regions Re.

Here, each of both side end regions Re of the tread portion 2 is set to have a width within a range of 5 to 40% of the width of the tread portion 2. If the width of the both end regions Re is less than 5%, the inclined portion of the inclined main groove 4 becomes too long and uneven wear easily occurs, while if the width exceeds 40%, the inclined portion of the inclined main groove 4 becomes short. All of them are unsuitable because the drainage property is impaired too much.

The inclined sub-groove 5 is opened in the circumferential main groove 3 at the center of the tread portion width, while the inclined main groove 4 is formed in the inclined sub-groove 5 near the width center of the tread portion 2, that is, near the equatorial plane E. It is suitable to adopt a configuration to open. Thereby, the water in the center area of the width of the tread portion 2 can be efficiently drained from the ground contact surface to both outsides. In addition, the formation of a sharp projecting corner on the stepping side of the block 6 on the ground contact surface is avoided, the rigidity of the block 6 is maintained, and the driving and braking performance on ice is improved.

The groove width of the inclined sub-groove 5 is set to be in the range of 10 to 80% of the groove width of the inclined main groove 4, thereby contributing to an improvement in driving force and braking force on ice and snow. If the groove width of the inclined sub-groove 5 is less than 10%, it is not possible to improve the driving force and braking force on snow, whereas if the groove width is more than 80%, each block 6 to 8 becomes too small and the rigidity is reduced. Becomes noticeable,
In particular, since the driving force and the braking force on the ice are reduced, both cases are unsuitable.

The average inclination angle of the inclined sub-groove 5 extending in the curved direction with respect to the equatorial plane E is set in the range of 40 to 85 ° in order to secure the driving and braking performance on snow. However, from the aspect of reducing uneven wear of each of the blocks 6 to 8, the average inclination angle is preferably in the range of 50 to 80 °.

The circumferential main groove 3 is formed in a straight shape so that the skid resistance on snow is superior and the drainage on a wet road surface is excellent. On the other hand, the circumferential main groove 3 is
With respect to the equatorial plane, both groove edges 3o (outgoing groove edges) and 3i (incoming groove edges) which alternately enter and exit extend repeatedly in substantially parallel.
By providing both groove edges 3o and 3i that enter and exit the circumferential main groove 3, compared to a main groove of a straight groove edge that extends over the entire circumferential direction,
Increases edge components and contributes to improvement of driving / braking performance.

Finally, a sipe 10 is provided in each of the blocks 6 to 8. This further improves the performance as a studless tire on ice.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radial ply tire for a passenger car having a size of 195 / 65R15 and a tread pattern provided in a tread portion 1 follows the one shown in FIG. The negative ratio of the entire tread portion 2 is 38%, and the inclined main groove 4 is 45 °.
Angle of inclination and a groove width of 7 to 9 mm.
Has an average inclination angle of 67 ° and a groove width of 4.5 mm (56% of the groove width of the inclined main groove 4). The width of each side edge region Re was set to 10% of the width of the tread portion 2. The width of the sipe 10 is 0.5 mm.

Example For evaluating the performance of the example tire, a conventional example tire having a tread pattern shown in FIG. 2 was prepared.
The only difference from the example tires is the tread pattern.
Using these two types of tires as test tires, the following six types of actual vehicle tests were performed.

(1) Snow Feeling Test: Comprehensive evaluation of braking performance, starting performance, straight running performance and cornering performance on a test course on a snow-covered road. (2) Brake test on snow: Vehicle speed 40 km / h on compact snow
Measurement of braking distance when full braking is applied from (3) Traction test on snow: linear distance 50 on compacted snow
Measurement of acceleration time from start at m. (4) Ice feeling test: Comprehensive evaluation of braking performance, starting performance, straight running performance and cornering performance on a test course on an ice plate road surface. (5) Brake test on ice: Vehicle speed 20 km / h on ice plate
Measurement of braking distance when full braking is applied from (6) Wet hydroplaning resistance test: Feeling evaluation of hydroplaning occurrence limit speed when passing through a wet road surface having a water depth of 5 mm. All of the above are summarized as indices with the conventional tire being 100, and the larger the value, the better. Table 1 shows the test results.

[0039]

[Table 1]

From the results shown in Table 1, it can be seen that the tires of the present invention are excellent not only in the braking and driving performance on ice and snow, but also on the cornering performance on ice and snow, and also in the wet performance, in comparison with the conventional tires. It can be seen that it has improved.

[0041]

According to the first to eleventh aspects of the present invention, the hydroplaning resistance on wet road surfaces is further improved with excellent drainage performance, and braking and driving on icy and snowy road surfaces are achieved. And a cornering performance can be provided at the same time at a highly excellent level.

[Brief description of the drawings]

FIG. 1 is a development view of a tread of a tire according to the present invention.

FIG. 2 is a development view of a tread of a conventional tire.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tread part 2 Tread surface part 3 Circumferential main groove 3o Outer side edge of circumferential main groove 3i Entrance edge of circumferential main groove 4 Inclined main groove 4e ₁ Depressed side groove edge of inclined main groove 4e ₂ Ejection of inclined main groove Side groove edge 4es Groove edge step of inclined main groove 5 Inclined sub groove 6, 7, 9 Block 10 Sipe E Tire equatorial plane Te Tread side end Re Side end area X Tire rotation direction

Claims (11)

[Claims] The tread portion has at least one main groove extending in the circumferential direction at the center of the width of the tread portion, and an inclined main portion inclined in an arrow shape from each of both end regions on the tread portion and extending toward the central circumferential main groove. A groove, and an inclined sub-groove branching off from the inclined main groove near each of the tread portion side end regions and extending in the direction opposite to the inclined main groove toward the center of the tread portion width, and having two types of tread portions. In the pneumatic tire having a rotation direction designated, having an arrangement of a number of directional blocks defined and formed by the main groove and the sub-groove, the inclined main groove is such that the main groove portion inside the tread side portion both end regions is the tire equator. An inclination angle in the range of 30 to 65 ° with respect to the plane,
The inclined main groove has a groove width wider than the groove width of the inclined sub-groove, and the inclined main groove has at least two groove edge steps at one groove edge of the main groove portion forward in the tire rotation direction. A pneumatic tire characterized in that the groove width of the inclined main groove is increased at a groove edge step. 2. In the tread portion region inside the both end regions,
One groove edge of the inclined main groove extends straight inward and outward from the groove edge step, the other groove edge of the inclined main groove extends straight over the entire block, and both groove edges of the inclined sub-groove are curved. The tire according to claim 1, wherein the tire extends. 3. The tire according to claim 1, wherein the groove edge step is located in a central region of a block edge along the inclined main groove. 4. The inclined main groove according to any one of claims 1 to 3, wherein the groove width gradually decreases from the inside to the outside of the tread portion between the adjacent groove edge steps. Tires. 5. The tire according to claim 1, wherein the inclined main grooves in both end regions of the tread portion have an inclination angle in the range of 80 to 90 ° with respect to the tire equatorial plane. 6. The tire according to any one of claims 1 to 5, wherein each of the two end regions on both sides of the tread portion has a width within a range of 5 to 40% of the width of the tread portion. 7. The inclined sub-groove is opened in a central circumferential main groove,
The tire according to any one of claims 1 to 6, wherein the inclined main groove is formed in an inclined sub-groove near the center of the tread portion width. 8. The inclined sub-groove has a groove width of 10 to 8 times the groove width of the inclined main groove.
The tire according to any one of claims 1 to 7, having a groove width in a range of 0%. 9. The inclined sub-groove is formed at an angle of 40 to the tire equatorial plane.
The tire according to any one of claims 1 to 8, having an average inclination angle in a range of 85 °. 10. The central circumferential main groove has a straight shape, and both edges of the main groove alternately enter and exit with respect to the tire equatorial plane and extend substantially in parallel. The tire described in one item. 11. The tire according to claim 1, wherein each of the plurality of directional blocks includes a plurality of sipes.