JP3113388B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire suitable for use as a studless tire for heavy loads, light trucks, and the like, and more particularly, to an improvement in wandering performance, performance on ice and snow and in muddy soil. To bring.

[0002]

2. Description of the Related Art In recent years, various types of studless tires without spikes have been marketed due to restrictions on the use of spike tires and the like. Above all, as a general tread pattern of a studless tire used for a heavy-duty vehicle, a light truck, or the like, as shown in FIG. 6, the tread pattern is continuous with a central portion of the tread tread portion 21 in a zigzag manner in a tread circumferential direction. A circumferential groove 22 is provided, and a staggered and zigzag-shaped circumferential groove 2 which is also continuous in the circumferential direction is formed on each side of the circumferential groove 22.
3 and 24 are sequentially provided, and a plurality of width-direction grooves 25 intersecting these circumferential grooves 22, 23 and 24 and opening at the tread grounding ends are provided in the tread circumferential direction. When a plurality of block rows 26, 27, and 28 are formed by these grooves 22, 23, 24, and 25 at intervals, the respective blocks except the shoulder block 28a include:
Three sipes extending zigzag in the tread width direction
A shoulder block 28a is provided in the shoulder block 28a in a zigzag fashion in the circumferential direction of the tread, and in addition to two sipes 30 completely crossing the block 28a, a zigzag circumferential groove is provided.
A short sipe 31 that extends from 24 in the tread width direction, which also bends in a zigzag manner, and ends without intersecting with the circumferential sipe 30 described above, and extends linearly in the tread width direction from the tread contact edge. There is another type in which two other parallel sipes 32 that end without intersecting the circumferential sipes 30 are provided. Such a studless tire can exhibit excellent performance on ice and snow by the action of the above-described tread pattern and the unique tread compound.

[0003]

However, in this studless tire, the tread shoulder portion is formed in a square shape called a square shoulder, particularly from the viewpoint of enhancing the performance on snow, so that the wandering resistance is low. was there. This was to be further lengthened by the fact that most studless tires used a radial structure with lower wandering resistance than the bias structure.

[0004] For this reason, as shown in a perspective view of a main portion in FIG. 7, a flat inclined portion 34 is provided on a portion of each shoulder block 28a outside the tread width direction from the grounding end 33 so as to be directed outward in the radial direction and tread. The flat inclined portion 34 facing outward in the width direction has an intersection angle θ with respect to the tire equatorial plane in the range of 30 to 50 °, and the width thereof on the extension of the tread tread surface is 4 to 16 mm. There has been proposed a tire provided with two linear sipes 35 on the inclined portion 34 extending parallel to each other in the tread width direction and entering the tread surface. According to this, in addition to the wandering resistance performance, the improvement of the performance on snow and the performance of mud were recognized, but it was still impossible to realize a satisfactory performance.

Accordingly, the present invention sufficiently improves the wandering performance and effectively improves the performance on ice and snow and the mud without the risk of lowering the performance on ice and chipping of the tread rubber due to the arrangement of the sipe. Provide a pneumatic tire, particularly a shoulder block structure, which can be made to be inflated.

[0006]

The pneumatic tire according to the present invention is provided with a flat inclined portion on the outer side in the tread width direction from the tread ground end of each shoulder block, and the tread is provided on the flat inclined portion. At least one, for example, two sipes extending in the width direction are provided, and both ends of the flat inclined portion in the circumferential direction of the tread extend substantially parallel to the width direction groove and shallower than the width direction groove. Edged by a notch groove having a depth, the width of each notch groove is set in the range of 10 to 30%, more preferably 15 to 23% of the tread circumferential length of the shoulder block, and the notch grooves The inner end in the tread width direction is terminated without opening in the circumferential groove on the inner side from the grounding end, and is provided on the flat inclined portion so as to extend in parallel with each other. Rhino in the book Of each of the sipe ends in the tread width direction on the inward side from the grounding end without being grooved in another sipe having a different extending direction, and the sipe on the inward side from the grounding end. Is provided with a portion having a length in the tread circumferential direction. Note that the term “sipe” here means a narrow groove whose groove walls are in contact with each other in the ground contact surface when the tire is rolling.

[0007] In such a tire, more preferably, the inclined portion sipe is provided at an inner portion in the tread width direction from the ground contact end.
A portion extending zigzag in the tread width direction is provided, and preferably, a portion extending zigzag or straight in the tread circumferential direction is provided in the same portion.

More preferably, the shoulder block is provided with two other types of sipes extending in the tread circumferential direction and the tread width direction, and one type of sipe extending in the tread width direction is provided on the other blocks except the shoulder block. Only.

[0009]

In this pneumatic tire, the flat inclined portion provided in the shoulder block has two ends in the circumferential direction of the tread which are provided separately from the width direction grooves and have notches having a depth much smaller than the width direction grooves. Groove with a groove, and, while extending each notch groove to the tread tread portion, terminate without opening the circumferential groove, and in the flat inclined portion,
By providing at least one, preferably a plurality of sipes extending in the tread width direction, it is possible to effectively reduce the rigidity of the shoulder block portion provided with the flat inclined portion with the notched grooves and sipes, As a result, the reaction force generated in the lateral direction of the tire, in other words, the reaction force generated in the tread width direction of the tire can be sufficiently reduced, and the occurrence of wandering can be effectively prevented.

In other words, when the notch groove is set to a depth close to the width direction groove, the rigidity of the shoulder block portion becomes too low, and the wear resistance of the block portion is reduced, and the chipping of the block occurs. Furthermore, if the notch groove is made shallow as described above, while the snow and mud performance of the tire is reduced, the rigidity of the block portion can be obtained, and the block edge can be provided. Can be sufficiently bitten into snow and mud, so that in addition to wandering performance, performance on ice and snow and mud can be greatly improved.

[0011] The depth of the notch groove is 5% to 20% of the width of the groove in the tread tread portion, and is 15% to 40% in the inclined portion in the direction perpendicular to the inclined portion. . In addition, here, by extending the notch groove substantially parallel to the width direction groove, it is possible to equalize the reduction in rigidity of the shoulder block, and thereby, the wandering property and the wear resistance of the block portion can be improved. And the resistance to chipping of the block can be achieved at the same time.

By extending the notch groove to the tread surface, the block rigidity can be effectively reduced, and the lateral reaction force of the tire can be sufficiently reduced. At the same time, the ice and snow performance and the mud performance can be greatly improved by the block edge. Further, by terminating the block without opening the groove in the circumferential direction, the block rigidity necessary for ensuring the chipping resistance, the wear resistance and the wear resistance of the block can be effectively obtained.

By the way, in this tire, the width of the notch groove is set to 10 to 30 times the length of the shoulder block in the tread circumferential direction.
%, More preferably 15 to 23%, optimizes the stiffness of the sloped section and also optimizes the reaction force generated when subjected to lateral forces, thereby producing wandering Can be more effectively prevented, and at the same time, the block edges in the sloped section can also function more fully.

That is, if it is less than 10%, the occurrence of wandering cannot be effectively prevented, and if it exceeds 30%, the abrasion resistance and uneven wear resistance of the shoulder block are reduced.

Further, at least one sipe provided on the flat inclined portion of the shoulder block functions together with the notch groove to make the rigidity of the inclined area more appropriate.
And, the portion of the sipe, which has a length in the tread circumferential direction, provided on the tread tread portion,
By absorbing energy by crushing the part, the generated reaction force is further optimized.

By extending the sipe to the tread surface portion, the rigidity of the block can be reduced more effectively, and the amount of sipe crushing can be increased. The reaction force can be reduced sufficiently, and the sipe edge can greatly improve the ice and snow properties. In addition, by terminating it without opening the other sipes, it is possible to obtain the block rigidity necessary for securing the chipping resistance of the block, the chipping resistance, and the wear resistance, and also to set the circumferential sipe 10 to the shoulder block. The lateral reaction force can be further reduced.

In such a pneumatic tire, the portion of the sipe provided on the flat inclined portion of the shoulder block, extending to the tread tread portion, has a portion having a length in the tread circumferential direction, and is zigzag in the tread width direction. When the portion extending in the shape is provided, the sipe's preference can be lengthened, and the sipe crushing amount can be further increased, so that the lateral reaction force can be further reduced.

When a similar extending portion is provided with a portion extending in a zigzag manner in the circumferential direction of the tread, the squeeze amount of the sipe further increases as the number of peripherals of the sipe increases. The lateral reaction force can be reduced more effectively. When the zigzag portion is a portion extending linearly in the circumferential direction of the tread, the sipe enters at 90 ° with the width direction sipe, that is, the sipe enters at 90 ° with the lateral input, so that the lateral input is effectively performed. Can be absorbed.

Further, the shoulder block is provided with two types of other sipe extending from the tread circumferential direction and the tread width direction, which are different from the inclined portion sipe, and other blocks except the shoulder block are provided in the tread width direction. When only one type of sipe is provided, not only can the heel and toe wear of the shoulder block be suppressed as much as possible and the lateral input can be reduced, but also the balance between the sipe edge in the traveling direction and the cornering direction can be balanced. It can improve the ice and snow properties.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a tread pattern showing one embodiment of the present invention, and FIG. 2 is a perspective view of a main part of a shoulder block. In this example, almost as described in the prior art,
A circumferential groove 2 is formed in the center of the tread tread portion 1 in a zigzag manner in the circumferential direction of the tread. Each side of the circumferential groove 2 is also formed in a staggered and zigzag manner also in the circumferential direction. Are provided in order at predetermined intervals, and extend in such a manner as to intersect with the respective circumferential directions 2, 3, and 4 and open at the tread contact ends. The width direction 5 of the book is provided, and these respective grooves 2, 3, 4, 5 form respective block rows 6, 7, 8 on each side of the zigzag circumferential groove 2 at the center of the tread. I do.

In this example, each side end portion of the width direction groove 5, in other words, in the shoulder block row 8, a portion that contributes to the division of each block 8a is:
It extends straight without a bend.

Each of the blocks 6a and 7a of the other block rows 6 and 7 except the shoulder block row 8 is provided with three sipes 9 extending in a zigzag manner in the tread width direction. Of the sipe 9 are extended from the staggered circumferential grooves 3 toward the zigzag circumferential grooves 2 and 4, and are terminated without opening the zigzag circumferential grooves 2 and 4. Further, another one sipe 9 is extended between the two sipe 9 from the zigzag circumferential grooves 2, 4 in the opposite direction to the zigzag circumferential grooves 2, 4, and opened to the staggered circumferential groove 3. Finish without grooving.

Each block 8a of the shoulder block row 8 has two sipes 10 extending zigzag in the tread circumferential direction and crossing the same, and the zigzag circumferential grooves 4 extending in the tread width direction. One sipe 11 is provided which extends in a zigzag manner and ends without crossing any sipe 10.

Further, in the illustrated example, as shown in FIG. 2, a flat inclined portion 13 is provided on the outer side in the tread width direction from the tread ground end 12 of each shoulder block 8a so as to face outward in the radial direction and outward in the width direction. , This flat slope 13
Both ends in the circumferential direction of the tread are extended by a notch groove 14 extending substantially parallel to the width direction groove 5 and having a depth smaller than the width direction groove 5. And these notched grooves
The width 1 of 14 is set to 10 to 30% of the tread circumferential length L of the shoulder block 8a, and the inner end of each of them in the tread width direction is located on the inner side in the width direction from the grounding end,
The process is terminated without opening any circumferential grooves.

In addition, here, in the flat inclined portion 13, two mostly sipe 15 extending in parallel with each other in the tread width direction are provided, and each of the sipe 15 is provided with a notch groove 14. Are extended to the inside of the tread tread portion 1 beyond the end position of the tread, and the respective inner end portions thereof are formed as bent portions 16 extending in the tread width direction in a zigzag manner. Here, the bent portion 16 has a length component in the tread circumferential direction in addition to a length component in the tread width direction.

Incidentally, the sipe here has a depth of approximately 0.7 times the widthwise groove 5 from the tread tread portion, as shown in a sectional view passing through the center line of the sipe 15 in FIG. The depth of the outer tread edge is about 2 mm deeper than the other parts.

According to the pneumatic tire configured as described above, in particular, as described above, under the appropriate block rigidity, based on the action of the notch groove 14 and the sipe 15 provided in the shoulder block 8a. Thus, the wandering resistance can be sufficiently improved, and the snow and mud performance can also be effectively improved.

FIGS. 4 and 5 are perspective views of main parts showing another example of a sipe provided on a flat inclined portion. Figure 4 shows each sipe
15 is an example in which each bent portion 17 is continuous with each other as a bent portion 17 extending in a zigzag manner in the tread circumferential direction, and FIG. 5 shows the tread inner end of each sipe 15. This is an example in which both portions are made continuous with each other as a straight portion 18 extending linearly in the tread circumferential direction.

In these embodiments, the bent portion 17 and the straight portion 18, respectively, of the sipe 15 make it possible to sufficiently increase the length component of the sipe in the circumferential direction of the tread, so that the sipe 15 can be prevented from reacting in the lateral direction of the tire. Since the force can be more effectively reduced, the wandering resistance can be more effectively improved.

(Comparative Example) Hereinafter, comparative tests of the inventive tire and the conventional tire on ice performance, wear resistance, uneven wear resistance, snow performance and wandering resistance will be described. ◎ Test tire The tire size is 7.00R16.

Inventive tire 1 A tire having the structure shown in FIGS.
The width of the sipe is 0.7 mm at the sipe 15 provided on the flat slope 13.
0.5 mm in the other sipe, the extension length tw of the sipe 15 in the tread tread surface is 4.5% of the tread contact width TW,
The extension length tw ₁ of the notch groove 14 in the tread tread surface is set to 1.9% of the tread contact width TW, and the flat inclined portion is formed.
13 with an angle θ of 45 ° with respect to the tread equatorial plane and a width of the inclined portion 13 of 9.9 mm.

Inventive tire 2 A tire having the shoulder block shown in FIG. 4, which is the same as the inventive tire 1 except for the shape of the sipe 15. Inventive tire 3 A tire having the shoulder block shown in FIG. 5, which is the same as the inventive tire 1 except for the shape of the sipe 15. -Conventional tire A tire having the structure shown in Figs.

◎ Test method The above-mentioned tires were mounted on a three-ton truck and the actual vehicle was run. For the performance on ice, the actual vehicle running feeling and the actual vehicle braking feeling on the ice test course were determined.
In addition, the performance on snow was evaluated for the same feeling as the performance test on ice on the snow test course, and the abrasion resistance was evaluated on dry general roads, highways, and mountain roads at 45:50, respectively. : The wear amount of the main grooves (2, 3, 4) after running at a ratio of 5 was measured, and the wear resistance was evaluated with respect to the heel and toe of the adjacent shoulder blocks after the above-described running was completed. The steps of wear were measured and evaluated. Further, the wandering resistance was evaluated in terms of the actual driving feeling on a dry test course and a snowy road course.

◎ Test results Table 1 shows the results of each test using the conventional tire as a control.
To the exponent. The larger the index value, the better the result.

[Table 1] According to Table 1, it is clear that all of the inventive tires can effectively improve both the wandering resistance performance and the performance on ice and snow.

[0035]

According to the present invention, in particular, by improving the shoulder block, it is possible to effectively improve the wandering resistance as well as the snow performance and Mud performance can also be improved.

[Brief description of the drawings]

FIG. 1 is a tread pattern showing an example of the present invention.

FIG. 2 is a perspective view of a shoulder block.

FIG. 3 is a cross-sectional view taken along a center line of an inclined portion sipe.

FIG. 4 is a perspective view showing another example of the inclined portion sipe.

FIG. 5 is a perspective view showing still another example of the inclined portion sipe.

FIG. 6 is a diagram illustrating a conventional tread pattern.

FIG. 7 is a diagram illustrating a shoulder block.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tread tread part 2,3,4 Circumferential groove 5 Width groove 6,7,8 Block row 6a, 7a, 8a Block 9,10,11 Sipe 12 Tread ground end 13 Flat inclined surface 14 Notch groove 15 Sipe 16 Bent part 17 Bent part 18 Straight part l Notch groove width L Tread circumferential length

Claims (4)

(57) [Claims] 1. At least two circumferential grooves extending continuously in the circumferential direction of the tread, and a plurality of width grooves extending intersecting the circumferential grooves and opening the respective tread grounding ends. Thereby, a plurality of block rows are formed on the tread tread, and a plurality of sipes are formed on each block of the block row, and each shoulder block has
A pneumatic tire provided with a flat inclined portion at a portion outside the tread width direction from the ground contact end, and provided with at least one sipe extending in the tread width direction on the flat inclined portion, wherein the flat inclined portion has a tread circumference. Direction edges are extended substantially parallel to the width direction grooves and are bordered by notch grooves having a shallower depth than the width direction grooves, and the width of each notch groove is defined by the tread circumferential length of the shoulder block. 10 ~
The cutout groove has a range of 30%, and the inner end of the notch groove in the tread width direction is terminated on the inner side from the ground contact end without being formed in the circumferential groove. The inner end of the provided sipe in the tread width direction is terminated on the inner side from the grounding end without forming a groove in another sipe, and the tread peripheral portion is provided on the inner side of the sipe from the grounding end. A pneumatic tire provided with a portion having a length in the direction. 2. A sipe provided at a flat inclined portion of each shoulder block, at a portion inside a tread width direction from a ground contact end,
The pneumatic tire according to claim 1, further comprising a portion extending in a zigzag shape in a tread width direction. 3. A sipe provided at a flat inclined portion of each shoulder block, at a portion inside a tread width direction from a ground contact end,
The pneumatic tire according to claim 1, further comprising a portion extending in a zigzag or linear shape in a circumferential direction of the tread. 4. The shoulder block is provided with two types of sipes extending in each direction of the tread circumferential direction and the tread width direction, and the other block is provided with one type of sipes extending in the tread width direction. 3. The pneumatic tire according to any one of 3.