JP3226966B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A pneumatic tire, particularly a pneumatic radial tire having a rib-lug tread pattern for heavy loads, is provided with an improved pneumatic tire capable of improving both steering stability on dry and wet road surfaces. It is something to offer.

[0002]

2. Description of the Related Art Pneumatic radial tires used for wheels for heavy loads, such as trucks and buses, include ribs and ribs.
Rug tread patterns have been more widely used than before.

One of the patterns has three main grooves extending in a zigzag shape along the outer periphery in the central region of the tread, and only the main groove occupying the equator is defined by the main groove at the bent top. A narrow groove extending laterally to the middle of the land portion is arranged, and in the remaining area on both sides of the tread, cut grooves that do not reach the main groove are arranged at intervals along the outer periphery of the tread.

Another rib / lug type pattern has a similar main groove in the center area of the tread, and the central main groove on the equator is larger than the width of the main grooves on both sides sandwiching the same. A narrow width is provided, and a lateral groove extending across the center of the main groove is provided between the bent tops of the main grooves on both sides, and in the remaining area on both sides of the tread, facing the main grooves on both sides at intervals along the outer periphery of the tread. It is arranged by arranging the cut groove which does not reach this.

[0005]

A tire to which the former of the above-described rib / lug tread patterns is applied has excellent wear resistance, but has insufficient edge effect in the central region of the tread, so that steering stability on a wet road surface is poor. There is difficulty,
On the other hand, the latter has excellent steering stability on a wet road surface, but has low block rigidity in the central region of the tread, and lacks steering stability and abrasion resistance on a dry road surface.

[0006] In view of the above, it is possible to improve the steering stability on a wet road surface without deteriorating the abrasion resistance, and to improve the steering stability on a dry road surface at the same time.
It is an object of the present invention to provide a pneumatic tire having a lug tread pattern.

[0007]

According to the present invention, at least three main grooves extending in a zigzag shape along the outer periphery of a central area of a tread, and a large number of cuts toward the main grooves in the remaining areas on both sides of the tread. And a groove, the pneumatic tire having a pattern, a land row sandwiched between the main grooves,
The main groove, the branch grooves extending parallel to each other at the recesses on both side corners of each land portion row and inclined with respect to the tread width direction, alternately cut from the main groove, and approximately the branch grooves adjacent to each other. The pneumatic tire is characterized in that the blocks are arranged in a substantially S-shaped configuration defined by connecting grooves that connect every other central portion. Here, the dividing groove extends over a length of 10 to 90% of the block width measured in the extending direction of the groove,
The branch groove and the connecting groove have a groove width of 10 to 90% with respect to the main groove, and the branch groove has a width of 40 to a plane including the tread circumference.
It is practically preferable that the inclination angle is 85 °, and the connecting groove is also an inclination angle of 5５〜60 °.

FIG. 1 shows an example of a block lug pattern according to the present invention in a plan development view of a part of a tread.
In the drawing, reference numerals 1 and 2 denote three main grooves extending in a zigzag shape along the outer periphery in the central region of the tread T, distinguished into a central main groove and main grooves on both sides. It extends in parallel with each other at the recesses on both sides of each land portion row sandwiched therebetween, and is alternately cut from the main grooves 1 and 2 to incline the tread width direction and divide the land portion row S. The branched groove 4 is a connecting groove that connects almost every other central portion of the adjacent branch grooves 3, and 5 is a block that divides the land row S by the main grooves 1, 2, the branch groove 3, and the communication groove 4. It is. 6 in the figure
Are a number of cut grooves toward the main groove in the remaining area on both sides of the tread T, and the cut grooves 6 form lugs on both sides of the tread T.

[0009] branch groove 3 has a length L ₂ which respect the width L ₁ of the block 5 measured along the extending direction of the groove corresponding to 10-90%, and the branch grooves 3 and contact groove 4 has main grooves groove width W ₂ of the relative groove width W ₁ of 10~90% 2, _{W 3.} The branch groove 3 and the connecting groove 4 are 50 to _{1 with} respect to the groove depth d1 of the main groove 2.
What is necessary is just to have a groove depth d ₂ of 00%.

[0010]

The land / groove shape of the rib / lug pattern is inclined in the tread width direction in the land row S from the main grooves 1, 2 and the recessed corners thereof to the middle stop of the width of the land row. The tread is formed by a land portion composed of a block 5 which is divided into a substantially S-shape by a branched groove 3 cut into the groove 3 and a connecting groove 4 which connects adjacent ones almost everywhere in the center of the branch groove 3. A decrease in tread stiffness in the central region of T is suppressed, and steering stability on wet road surfaces and dry road surfaces can both be improved.

[0011] These branching groove length L ₂ of the branch grooves 5 cut into at internal corner recesses of the land row on land row as 10-90% among them 40% to 80% of the maximum width L ₁ of the block 5 Connecting the adjacent phase ratios in the substantially central portion of 3 with the connecting groove 4 helps to improve drainage. However, if the length of the branch groove 3 is less than 10%, the effect of improving the steering stability on wet road surfaces is low. If it exceeds 90%, it is difficult to improve steering stability on dry roads due to reduced tread land rigidity. The 10% to 90% of the groove width W ₁ of branch grooves 3 and the groove width W ₂ of the connecting groove 4 main grooves 2, among them 40% to 70%
If it is less than 10%, it is ineffective, and if it exceeds 90%, uneven wear (particularly, riverware) performance is significantly reduced.

The inclination angle of the branch groove 3 is preferably in the range of 40 to 85 ° with respect to the equatorial plane of the tire. If it is less than 40 °, the block rigidity at the block angle formed by the branch groove 3 and the main grooves 1 and 2 is reduced. Steering stability on a dry road surface is deteriorated, and if it exceeds 85 °, so-called heel and toe wear is likely to occur because the edges of the blocks 5 along the branch grooves 3 do not tend to separate from the ground contact surface during rolling of the tire at the same time. . The groove depth d ₂ of the branch groove 3 and the communication groove 4 is 20 to 100% of the groove depth d ₁ of the main groove 2.
In particular, it is preferably 50 to 100%, and if it is less than 20%, drainage cannot be ensured, and the effect on steering stability on a wet road is weak. In addition,
There is no point in exceeding 100%, that is, deeper than the main groove.

The land rows S sandwiched between the main grooves 1 and 2 as described above extend parallel to each other at the main grooves 1 and 2 and the recesses at the corners on both sides of each land section, A branch groove 3 inclined from the main grooves 1 and 2 alternately with respect to the tread width direction,
Since the connecting grooves 4 connecting the substantially central portions of the branch grooves 3 adjacent to each other alternately form the S-shaped blocks 5, the rigidity of the blocks 5 is greater than that of the conventional blocks. Also, since the branch groove 5 stops at the middle of the block 4, the rigidity does not become insufficient.

Therefore, the block lug pattern according to the present invention is excellent in steering stability and abrasion resistance on a dry road surface, and furthermore, the connecting groove 4 connects the substantially adjacent portion of the branch groove 3 at substantially the center. As a result, the drainage in the central region of the tread is improved because of communication with the main grooves 1 and 2, and the steering stability on a wet road surface is also improved by increasing the edge component.

[0015]

[Example] Tire size 10,000 R20 (Tread width 209mm)
) Has three main grooves 1 and 2 extending in a zigzag shape along the outer periphery in the central region of the tread T, and the central main groove 1 (groove width 10.5 mm, groove depth 16.3 mm) )
On the equator of the tire, both main grooves 2 (groove width 12mm, groove depth 1
(6.3 mm) was similarly arranged so as to sandwich the central main groove 1, and a tire based on a rib-lug pattern having cut grooves 6 arranged on both sides of the tread at intervals along the outer periphery of the tread was prepared.

According to the present invention, each of the land rows S sandwiched between the main grooves 1 and 2 as shown in FIG.
A connecting groove that extends in parallel with each other at the corner recesses on both sides thereof and that alternately cuts from the main grooves 1 and 2, and connects almost every central portion of the adjacent branch grooves 3. Groove 4
It becomes an arrangement of many blocks 5 partitioned by
Here, the length of the branch groove 3 is set to a length (25 mm) corresponding to 54% of the block width L ₁ (46 mm) measured in the extending direction of the groove.

The branch groove 3 has a groove width of 8 mm, the connecting groove 4 has a groove width of 6 mm, and each of the main grooves 1 and 2 has a groove width (13 mm).
62% and 46%, the groove depth is 14.8mm for both the branch groove and the groove depth, 88% of the groove depth of the main grooves 1 and 2 (16.8mm), and the inclination of the branch groove 3 with respect to the plane including the tread circumference. Angle is 60 °
The contact groove 4 was set at 20 °.

On the other hand, according to the prior art, as shown in FIG. 2, only the central main groove 1 has a narrow narrow groove 3 'which extends laterally to the middle of a land portion S defined by the main groove at the bent top. 3 and a lateral groove 3 ″ extending between the bent tops of the main grooves 2 on both sides and intersecting with the central main groove 1 as shown in FIG.
The tire performance was compared with a comparative tire that was different in the arrangement of. The results were as follows:

[0019]

[Table 1]

Next, in the place shown in FIG.
As a percentage of the maximum width l ₁ of the block 4 having a length l ₂ , the groove width W ₂ of the branch groove 3 and the groove width W 3 of the communication auxiliary groove 4
Each value of a percentage of the groove width W ₁ of each side main groove 2 of FIG. The results of examining the trends for steering stability effects and heel end toe generation amount on the evaluation in a wet road surface by the test driver 4 (a), ( FIG. 5B also shows the effects of the branch groove 3 and the communication groove 4 on the steering stability evaluation on a wet road surface.

[0021]

According to the present invention, it is possible to improve the steering stability on a wet road surface without reducing the wear resistance of a tread for a radial tire for heavy loads such as trucks and buses, and to improve the steering stability on a dry road surface. It can be realized according to the securing of performance.

[Brief description of the drawings]

FIG. 1 is a partially developed view of a tread according to the present invention.

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

FIG. 3 is a partially developed view of another conventional tread.

FIG. 4 is a performance graph.

FIG. 5 is another performance graph.

[Explanation of symbols]

 1, 2 main groove 3 branch groove 4 communication groove 5 block 6 cut groove S land row

Claims (3)

(57) [Claims] 1. A pattern comprising at least three main grooves extending in a zigzag shape along the outer periphery in a central area of a tread, and a number of cut grooves facing the main grooves in remaining areas on both sides of the tread. In the pneumatic tire, the land portion row sandwiched between the main grooves extends in parallel with each other at the main groove and both side corner recesses of each land portion row, and is inclined with respect to the tread width direction. The air is characterized by being arranged in an arrangement of substantially S-shaped blocks defined by branch grooves alternately cut from the main groove and communication grooves connecting almost every other central part of the adjacent branch grooves. Containing tires. 2. The branch groove has a length of 10 to 90% of the block width measured in the extending direction of the groove, and the branch groove and the communication groove have a groove of 10 to 90% of the main groove. The pneumatic tire according to claim 1, having a width. 3. The branch groove is formed on a plane including the tread circumference.
2. The pneumatic tire according to claim 1, wherein the inclination angle is 40 to 85 °, and the communication groove has an inclination angle of 5 to 60 °. 3.