JPH05169923A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To improve traction performance, braking performance, side-slip resistance and other performances on ice and snow. CONSTITUTION:For a block-pattered tire, sipes 7a, 9a, 11a in blocks 7, 9, 11 are formed with the straight portions 7b, 7c located in the respective side areas of the blocks and actually extended in a tread cross direction and the bent inclined portions 7d located between both straight portions to bring mutual communication and extended in inclination to the straight portions. The bent inclined portions 7d of the sipes located in spaces in a tread peripheral direction in the blocks are actually extended in parallel and the respective one ends of the sipes are open to the respective peripheral grooves on the opposite side in a block cross direction on an alternate basis in a tread peripheral direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire, and more particularly to a studless tire for passenger cars having improved performance on ice and snow.

[0002]

2. Description of the Related Art A conventional studless tire has a pattern structure of, for example, 4 to 4 continuous tires in the circumferential direction of the tread.
185 mm with a negative ratio of around 40% due to the five circumferential grooves and the widthwise grooves that intersect the circumferential grooves.
In the area where a large number of blocks with a standard pitch length of about 30 mm are sectioned in the tire cross-sectional width, the stipulation of the tire's traction performance and braking performance is defined as the first meaning Such a tire has a standard block size, and the required rigidity of the block and the hardness of the rubber are well matched, so that the tire has an excellent balance of ice and snow performance.

[0003]

However, in such a conventional technique, since only the sipes extending in the tread width direction are formed in the block, the traction performance and the braking performance of the tire are further improved. If only the number of sipes is increased under the same block area in order to bring about an improvement, the rigidity of the block portion divided by the sipes will be significantly reduced, and effective groundability cannot be obtained, As a result, there has been a problem that both traction and brake performance are degraded.

On the other hand, in order to give a better skid resistance to the tire, it is conceivable to add circumferential sipes to the block or to add grooves in the tread circumferential direction, but in either case. Even
There is a problem that the rigidity of the block is reduced as in the case described above by simply adding the block.

The present invention has been made as a result of studies aimed at solving such problems of the prior art, and the object of the present invention is to improve the shape of the sipe, in particular. Effectively improve both traction performance and braking performance of the tire,
At the same time, it is intended to provide a pneumatic radial tire capable of increasing the skid resistance so as to be well balanced with the improvement of those performances.

[0006]

A pneumatic radial tire of the present invention has a plurality of circumferential grooves continuously extending in the circumferential direction of a tread surface, and a pneumatic radial tire tending to extend in the tread width direction. A tire having a widthwise groove extending from the tread end to the other tread end, a block partitioned by each of these grooves, and a plurality of sipes formed in each block, the tire being formed in one block The respective sipes located in respective lateral areas of the block and extending substantially in the width direction of the tread, and between the both linear parts, so as to bring them into communication with each other. And a sloping bent portion that is formed by a sloping bent portion that extends obliquely with respect to a linear portion, and that is located at a distance in the tread circumferential direction in one block. Causes substantially parallel extending, and the one end of each of these sipes, each of the circumferential groove of the opposite side of the block width direction, is obtained by open grooves alternately tread circumferential direction.

More preferably, the straight portion on one side of one sipe is formed, for example, on an extension line of the straight portion on the other side of another sipe that is adjacent in the tread circumferential direction.

[0008]

In the pneumatic radial tire of the present invention, the sipes formed on the block are provided with linear portions which are located in their respective side regions and extend substantially in the tread width direction, and these linear portions. By forming a bending sipe that is located between them and has a bent inclined portion that brings them into communication with each other, the sipe is divided as compared to the case where the same number of widthwise sipes are formed in the same block. Since the bending rigidity and the shearing rigidity of each block portion in the tread circumferential direction are both high, it is possible to secure excellent ground contact property, and particularly to greatly improve the performance on ice.
Further, since the bent inclined portion of the sipe has a length component in the tread circumferential direction, it is possible to effectively improve the lateral slip resistance of the tire.

By the way, according to this tire, since the blade of the vulcanization mold, which contributes to the formation of sipes, also has a bent shape, even if the blade is made thin, sufficient blade strength is still obtained. As a result, the width of the sipes can be narrowed, the block rigidity can be further increased, and the performance on ice and snow can be greatly improved.

Further, in this tire, since the bent inclined portion of the sipe is located in the central area in the width direction of the block, the rigidity of each block portion in the circumferential direction of the tread can be more effectively increased, and It is possible to sufficiently open and close the sipe side end portion that substantially extends in the tread width direction against the external force in the circumferential direction.

Further, here, in the case where both ends of the sipe are opened by alternately opening one end of each sipe in each circumferential groove on the opposite side in the block width direction in the tread circumferential direction. In comparison, the rigidity of each block part can be increased, and the alternating open grooves of the sipes to the opposite circumferential groove apply a nearly uniform front-back force to each block part, and the sipes are even. Since it is opened to the side, the edge effect unique to the sipe can be further enhanced, and the uneven wear resistance of the block can be improved. In addition, when the straight portion on one side of one sipe is located on the extension line of the straight portion on the other side of the other sipe, the ease of opening the sipe can be sufficiently ensured. ..

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a tread pattern showing an embodiment of the present invention. The internal reinforcing structure of the tire is generally the same as that of the radial tire, and therefore the illustration thereof is omitted.

In the figure, 1 is a circumferential zigzag groove which is located at the tread center and extends continuously in the circumferential direction of the tread, and 2 is located on each side of the circumferential zigzag groove 1. This also shows two pairs of circumferential linear grooves that extend continuously in the tread circumferential direction. Reference numeral 4 denotes a pair of circumferential zigzag grooves which are located further to the side of the respective circumferential linear grooves 2 and extend in substantially the same manner as the circumferential zigzag grooves 1. These five circumferential grooves 1, 2, 4
Of these, the respective circumferential zigzag grooves 1 and 4 are
It has a bent zigzag shape without the trapezoidal bottom.

On the other hand, in this example, a widthwise groove 6 that extends from one tread end to the other tread end across all these circumferential grooves 1, 2 and 4 is formed at a predetermined interval in the tread circumferential direction. A plurality of widthwise grooves 6 are formed at each position, and the widthwise grooves 6 extend in the circumferential direction of the tread so as to overlap the circumferential grooves at a position reaching the circumferential grooves for some length. By doing so, it is made to extend in a substantially step shape as a whole. As shown in the drawing, each widthwise groove 6 has a step-like shape that descends to the right.

Here, each of the respective circumferential grooves 1, 2, 4 and the widthwise groove 6, more precisely each of the respective blocks 7, 9, 11 defined by them and their respective tread ends. In this case, each of the five sipes 7a, 9a, 11a is formed per block at a predetermined interval in the circumferential direction of the tread.

The sipes 7a, 9a, 11a per block
It is needless to say that the number of the blocks can be appropriately selected according to the arrangement pitch of the blocks. For example, when the width of the widthwise groove 6 is 7 mm, the arrangement pitch is 35 mm.
In case of, the number of sipes can be set to 5 as shown in the figure, and when the pitch is 28 mm,
The number of sipes can be set to 4.

Each sipe 7a, 9a, 11a is located in a respective lateral area of the block 7 and extends substantially in the width direction of the tread 7b, as will be described below by taking the sipe 7a as an example. , 7c and their linear portions, or in other words, located in the widthwise central area of the block 7, so as to bring these linear portions 7b, 7c into communication with each other, as well as the linear portions 7b, 7c. The bent inclined portion 7d which extends with respect to and also has a length component in the circumferential direction of the tread.
It is formed by and.

Further, the bent inclined portion 7d of such a sipe 7a is made to extend substantially parallel to that of each sipe 7a in one block, and each end of each sipe 7a in the block is further extended. Are alternately formed in the circumferential grooves 1 and 2 on the opposite sides in the width direction of the block in the tread circumferential direction.

In such a tire, more preferably, one sipe 7a has a linear portion on one side, for example, a linear portion 7c on the tread end side, of another sipe 7a adjacent to the sipe 7a in the tread circumferential direction. , The straight part on the other side,
For example, it is located on the extension of the linear portion 7b on the tread center side.

According to the tire configured as described above, as described above, it is possible to greatly improve both the traction performance on ice and snow, the braking performance, and the like, particularly under the action of sipes. At the same time, the action of the bent inclined portion of the sipe can also effectively improve the skid resistance.

FIG. 2 is a tread pattern showing another example of the present invention, in which two pairs of circumferential linear grooves 21 extending continuously in the tread circumferential direction are provided in the tread central area, and On the tread end side of the circumferential linear groove 21 of, continuous in the tread circumferential direction substantially similar to the circumferential zigzag groove of the embodiment described above, also provided a pair of circumferential zigzag grooves 22 in two, also, By further providing two pairs of circumferential linear sub-grooves 23 on the tread end side of the groove, the total number of circumferential grooves is 6, and each of the widthwise grooves is substantially the same as the above-described embodiment. Width groove 24
Where each of the blocks 25 to 28 is provided, four or five sipes 25a to 28a having the same configuration as described above are provided, respectively.

In this example, the bent sipe 25b, which is located in a portion of the block 25 in the central area of the tread and is adjacent to the respective widthwise grooves 24 and bends like a hook, is different from the sipe specified in the present invention. Although having a configuration, these sipes are commensurate with the peripheral block edge shape, and they also have respective components of a length component in the tread width direction and a length component in the tread circumferential direction. Therefore, it can exhibit the same function as other sipes.

Here, the tire shown in this example can also exhibit substantially the same function as that of the above-described embodiment, particularly under the action of the sipes 25a to 28a according to the present invention.

In FIG. 3, a circumferential zigzag groove 31 extending continuously in a sawtooth shape as a whole is provided in the central portion of the tread, and two pairs of circumferential straight lines are provided on each side of the circumferential groove 31. Grooves 32 are provided respectively, and circumferential zigzag grooves are provided on the tread end side of each circumferential linear groove 32.
Two pairs of circumferential zigzag grooves 33 having substantially the same configuration as 31 are provided respectively, and the total number of circumferential grooves is 5, and
The widthwise groove 34 reaching from one tread end to the other tread end, in particular, to each circumferential linear groove 33, to overlap in some circumferential length to extend in a substantially stepwise manner. And each block 35,
This is an embodiment in which 36 and 37 are divided and six sipes 35a and 36a each having substantially the same configuration as described above are formed in the other blocks 35 and 36 except the outermost block 37.
In this example, the straight portion on one side of one sipe 35a, 36a is located on the extension line of the straight portion on the other side of another sipe that flies one in the circumferential direction of the tread.

By the way, each of the outermost blocks 37 is formed with six sipes 37a extending substantially in the width direction of the tread so that the lateral rigidity of the blocks 37 can be sufficiently enhanced to control the vehicle on a dry road surface. The stability can be further enhanced. Then, one end of each of the sipes is opened to the circumferential zigzag groove 33 every other one, and both ends of the other sipes are terminated in the block, whereby sufficient block rigidity can be secured.

In the embodiment shown in FIG. 4, two pairs of circumferential linear grooves 41 are provided in the central area of the tread, and the circumferential linear grooves 41 are located at the tread end side positions.
A pair of zigzag grooves 42 whose center lines form a pulse-shaped concavo-convex are respectively provided, and these four circumferential grooves 41, 42 are intersected to extend from one tread end to the other tread end. Each of the plurality of widthwise grooves 43 has a bent zigzag shape like the zigzag groove shown in FIG. 1 and FIG. All the divided blocks 44, 45, 46 have the same structure as described above.
Each sipe 44a, 45a, 46a is formed, and the straight portion on one side of one sipe is extended on the extension portion of the straight portion on the other side of the other sipe, which is located two flying in the circumferential direction of the tread It is located in.

The respective embodiments shown in FIG. 3 and FIG. 4 can also bring about the same effects as the above-mentioned embodiments based on the configuration of the sipe peculiar to the present invention.

[0028]

COMPARATIVE EXAMPLE Hereinafter, a comparative test regarding the feeling on snow and ice and the braking performance on ice between the invention tire and the conventional tire will be described. ◎ Test tire size is 185/70 R13 and tread width is 140m
m, negative ratio 40%, sipe width 0.5mm. Invention tire 1 is a tire having the tread pattern shown in FIG.
5 blocks per block, with a pitch of 35 mm
Formed sipe of a book. The distance between sipes is 4.0 mm
And Invention tire 2 is a tire having the tread pattern shown in FIG.
The number of sipes per block and the sipes distance are the same as those of the invention tire 1. Invention tire 3 is a tire having the tread pattern shown in FIG.
6 blocks per block for blocks with arrangement pitch of 35 mm
Formed sipe of a book. Here, the spacing between sipes
It was 3.5 mm, and the length of the bent slope portion was made slightly longer than that of the invention tires 1 and 2. Invention tire 4 A tire having the tread pattern shown in FIG. 4,
6 sipes per block are formed in a block with an arrangement pitch of 35 mm at intervals of 3.5 mm, and the length of the bent inclined part is made longer than that of the invention tire 3. In the inventive tire 4 and the inventive tire 3, the rigidity of each block portion divided by the six sipes is secured by increasing the length of the bent inclined portion. Conventional tire having a tread pattern shown in FIG. 5,
A block with an arrangement pitch of 30 mm, with four sipes per block formed at an interval of 4.5 mm.

◎ Testing method The actual vehicle is run under the internal pressure and load conditions specified in JIS, and the feeling on snow is the performance of starting, accelerating, turning, climbing and braking on a circuit course on a compressed snow road surface. The ice feeling is obtained by evaluating the turning performance on the ice board with the feeling, and the braking performance on the ice is the braking distance from 40 km / h on the ice board. I asked.

◎ Test Results The results of each of the above tests are shown in Table 1 as an index using a conventional tire as a control. The larger the index value, the better the result.

[0031]

[Table 1] As shown in Table 1, it is clear that each of the invention tires can effectively improve both the feeling on snow and the feeling on ice and the braking performance on ice, as compared with the conventional tire.

[0032]

Thus, according to the present invention, in particular,
By improving the structure of the sipe, the traction performance on ice and snow, the braking performance, the skid resistance, and other performances can be improved sufficiently effectively compared with conventional tires.

[Brief description of drawings]

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

FIG. 2 is a tread pattern showing another embodiment of the present invention.

FIG. 3 is a tread pattern showing still another embodiment of the present invention.

FIG. 4 is a tread pattern showing another embodiment of the present invention.

FIG. 5 is a tread pattern showing a conventional example.

[Explanation of symbols]

1, 4, 22, 31, 33, 42 Circumferential zigzag groove 2, 21, 32, 41 Circumferential straight groove 6, 24, 34, 43 Width groove 23 Circumferential straight sub groove 7, 9, 11, 25, 26, 27, 28, 35, 36, 44, 45, 46 Block 7a, 9a, 11a, 25a, 26a, 27a, 28a, 35a, 36a, 44a, 45
a, 46a Sipe 7b, 7c Straight part 7d Bent inclined part

Claims (2)

[Claims] 1. A plurality of circumferential grooves extending continuously in the circumferential direction of the tread surface, and a widthwise groove extending in the tread width direction and extending from one tread end to the other tread end. And a block divided by these respective grooves, and a plurality of sipes formed in each block, wherein each sipes formed in one block is divided into respective side areas of the block. The linear portions that are located in the tread and extend substantially in the width direction of the tread, and the folds that are located between these linear portions to bring them into communication with each other and that are inclined with respect to the linear portions. The sipe of each sipe, which is composed of a curved inclined portion and is spaced apart in the tread circumferential direction in one block, extends the bent inclined portion substantially in parallel, and One end of each of the each of the circumferential groove of the opposite side of the block width direction,
Pneumatic radial tire with grooves open alternately in the tread circumferential direction. 2. The pneumatic radial tire according to claim 1, wherein a straight portion on one side of one sipe is formed on an extension line of a straight portion on the other side of another sipe.