JP2008132873A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enhancing on-snow/-ice performance and enhancing partial wear resistance without impairing the edge effect by sipes and grooves by realizing an adequate shape of a block land part. <P>SOLUTION: In the pneumatic tire, at least one block land part row comprising a large number of block land parts (2) is demarcated by arranging a plurality of circumferential grooves (3) extending substantially in the tire circumferential direction and a plurality of transverse grooves (4) for communicating two circumferential grooves (3) adjacent to each other in a tread part (1), and a plurality of sipes (5) is arranged in the block land parts (2). Further, a first groove (6) extending from one of a pair of edge parts or corner parts opposing each other to the other and terminating in the land part, and a second groove (7) extending in the direction across the first groove (6) with both ends thereof terminating in the land are arranged in at least one block land part (2). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the tread portion, a plurality of block land portions are provided by disposing a plurality of circumferential grooves extending substantially in the tire circumferential direction and a plurality of lateral grooves communicating two adjacent circumferential grooves. A block land portion row and a plurality of sipes disposed on the block land portion, and more particularly to a winter pneumatic tire. Improve running performance and uneven wear resistance on icy and snowy road surfaces.

  In order to eliminate dust pollution caused by spikes or studs protruding on the surface of the tread part, studless tires that do not have spikes and have excellent running performance on icy and snowy road surfaces have been developed.

  A feature almost common to conventional studless tires is that the tread portion is partitioned into a large number of block land portions, and a large number of sipes are arranged (see, for example, Patent Document 1). By arranging such a sipe, it is possible to obtain a so-called edge effect, which is an effect caused by the edge of the block land portion scratching the road surface, and a so-called drainage effect, which is an effect that the sipe sucks up a water film present on the ice road surface. it can. Therefore, from the viewpoint of only the edge effect and the drainage effect, it is considered that the performance on ice is improved by increasing the number of sipe arrangements, but this simultaneously reduces the block rigidity and reduces the ground contact area due to the bending deformation of the block, Rather, the performance on ice is lowered, and at the same time, dry handling performance and wet handling performance are also lowered, and further, uneven wear of the block land portion may be caused. Further, in order to ensure the performance on ice and snow while preventing such uneven wear, for example, Patent Document 2 discloses a negative rate of the tread portion by providing an inclined groove in the block land portion with respect to the tire circumferential direction. Since the edge component increases and the edge component increases, tires with improved performance on ice and snow are described. Furthermore, in Patent Document 3, in addition to the arrangement of the inclined groove inclined with respect to the tire circumferential direction, the edge component in a direction different from the inclined groove is increased by providing the sipe in the block land portion. A tire with improved performance on ice and snow is described.

JP-A-9-48216 Japanese Unexamined Patent Publication No. 57-121903 JP-A-63-134315

  However, in any of the tires described in Patent Documents 1 to 3, the performance on ice and snow is improved, but it cannot be said that the edge component in all directions is sufficiently secured due to the structure of the block land portion. Only the on-ice performance in a certain traveling direction is improved, and the on-ice performance in all traveling directions may not be sufficiently improved. In addition, uneven wear may occur because the edge components are not uniformly distributed in all directions.

  Accordingly, an object of the present invention is to provide a pneumatic tire that improves the performance on snow and ice while improving the uneven wear resistance by optimizing the shape of the block land portion.

  In order to achieve the above object, according to the present invention, a plurality of circumferential grooves extending substantially in the tire circumferential direction and a plurality of transverse grooves communicating two adjacent circumferential grooves are disposed in the tread portion. In the pneumatic tire in which at least one block land portion row composed of a large number of block land portions is partitioned and a plurality of sipes are arranged on the block land portion, at least one block land portion is formed. Extends from one of a pair of opposing edge portions or corners to the other, terminates in the land portion, extends in a direction intersecting the first groove, and both ends thereof terminate in the land portion. A pneumatic tire is provided with the second groove. With this configuration, assuming that block rigidity is maintained, edge components for all travel directions can be obtained evenly, so that on-snow performance is sufficiently improved while on-ice performance is improved, and uneven wear is prevented. be able to. Here, the “substantially tire circumferential direction” refers to a direction in which an angle formed by an imaginary line connecting the center positions of the groove width and the tire circumferential direction is ± 5 °.

  Moreover, it is preferable that the angle formed by the extending direction of the pair of first grooves is within a range of ± 5 °.

  Furthermore, it is preferable that the angle formed by the extending direction of the first groove and the extending direction of the second groove is in the range of 70 ° to 110 °.

  Furthermore, it is preferable that the block land portion has a pair of acute angle portions and obtuse angle portions, and a first groove is provided at the edge portion near the acute angle portion or in the vicinity of the acute angle portion.

  In addition, it is preferable that the extending direction of at least one of the first groove and the second groove is inclined with respect to the tire circumferential direction.

  Moreover, it is preferable that the extending direction of at least one of the first groove and the second groove is inclined with respect to the extending direction of the sipe.

  According to the present invention, it is an object of the present invention to provide a pneumatic tire that improves the performance on ice and snow and at the same time improves the uneven wear resistance by optimizing the shape of the block land portion. It becomes.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing one block land portion 2 of a tread portion 1 of a typical pneumatic tire (hereinafter referred to as “tire”) according to the present invention, and FIG. 2 is a block land portion shown in FIG. FIG. 3 is a plan view of the block land portion 2 of the tread portion 1 of another typical tire according to the present invention.

  In the tire according to the present invention, the tread portion 1 is provided with a plurality of circumferential grooves 3 extending substantially in the tire circumferential direction and a plurality of transverse grooves 4 communicating with the two adjacent circumferential grooves 3. At least one block land portion row composed of a large number of block land portions 2 is partitioned. In this way, by arranging one or more block land portion rows, the groove area increases and the negative rate increases, so it is possible to ensure basic performance on snow.

  The block land portion 2 is provided with a plurality of sipes 5 extending so as to intersect the tire circumferential direction. As described above, when a plurality of sipes 5 extending across the tire circumferential direction are arranged in the block land portion 2, the edge component of the block land portion 2 increases, so that basic performance on ice is also ensured. Can do.

  However, if the sipe 5 is excessively disposed in the block land portion 2, excessive bending deformation is caused in the block land portion 2 in the vicinity of the sipe, and the ground contact area is reduced. Rather, wet handling performance, dry handling performance and on-ice performance are degraded. To do. In addition, uneven wear of the block land portion 2 is caused. On the other hand, if the number of the sipe 5 is too small, a sufficient edge effect cannot be obtained, and the on-ice performance is not sufficiently improved. Furthermore, even if the number of sipe 5 is appropriate, the sipe 5 is disposed in the same direction. Therefore, only the performance on ice in a certain traveling direction is improved, and practically sufficient performance on ice. May not be obtained. On the other hand, in the tire of the present invention, the block land portion 2 is provided with grooves in different directions, i.e., different extending directions, so that any direction can be input to the block land portion. The edge effect can be exhibited, and the performance on ice and snow is improved. Moreover, since the 1st groove | channel 6 has one end opened to the tire circumferential groove, it extends into the block land portion from the opening portion, and the other end terminates inside the block land portion. The rigidity of the block land portion 2 is higher than that in the case where the ends of all the grooves are open, and the uneven wear resistance is improved.

  Moreover, it is preferable that the angle formed by the extending direction of the pair of first grooves 6 is within a range of ± 5 °. Because, when the angle formed by the extending direction of the pair of first grooves 6 exceeds the range of ± 5 °, the edge component is unevenly distributed in the block land, and the performance on ice cannot be sufficiently improved. This is because the rigidity of the block land portion 2 is also biased, which may easily cause uneven wear.

  Furthermore, the angle formed by the extending direction of the first groove 6 and the extending direction of the second groove 7 is preferably in the range of 70 to 110 °, more preferably in the range of 80 to 100 °. This is because when the angle is less than 70 ° or more than 110 °, the edge components of the first groove 6 and the second groove 7 are unevenly distributed, and the performance on ice is not sufficiently improved. This is because the rigidity of the land portion 2 is also uneven, which may cause uneven wear.

  In addition, the block land portion 2 has an acute angle portion and an obtuse angle portion, and the first groove 6 is preferably provided in the acute angle portion or in the vicinity of the acute angle portion. This is because the provision of the first groove 6 in the vicinity of the acute angle corner or in the vicinity of the acute angle corner secures more edge components in the tire width direction in particular than the provision of the first groove 6 in the obtuse angle corner or in the vicinity of the obtuse angle corner. This is because the cornering performance on ice and snow may be improved. FIG. 2 shows an embodiment in which the first groove 6 is opened at an acute angle portion, and FIG. 3 shows an embodiment in which the first groove 6 is opened in the vicinity of the acute angle portion.

  In addition, it is preferable that at least one of the extending directions of the first groove 6 and the second groove 7 is inclined with respect to the tire circumferential direction. This is because, when traveling on snow, it becomes easier to slip than when traveling on a dry road surface, and an edge component is more required in the tire circumferential direction, so at least one of the first groove 6 and the second groove 7 is in the tire circumferential direction. This is because the edge effect with respect to the tire circumferential direction can be increased and the snow traction and braking performance are improved.

  Moreover, it is preferable that at least one of the extending directions of the first groove 6 and the second groove 7 is inclined with respect to the extending direction of the sipe 5. This is because the extending direction of the first groove 6 and the second groove 7 is preferably inclined with respect to the tire circumferential direction, and at least one of the first groove 6 and the second groove 7 is the same as the edge component by the sipe 5. If there is only an edge component in the direction of, the edge component in a certain direction is concentrated and increases, and the edge component in the block land portion 2 becomes non-uniform, so that sufficient on-ice performance is obtained. This is because there is a possibility of causing uneven wear at the same time. It is particularly preferable that the extending direction of the first groove 6 and the second groove 7 is inclined with respect to both the extending direction of the sipe 5 and the tire circumferential direction, and according to this, with respect to input from more directions. Since the effective edge effect can be exhibited, there is a possibility of further improving the performance on snow and snow and the wear resistance.

  The block land portion 2 shown in FIG. 1 can be appropriately changed according to the required performance on ice and snow. For example, the block land portion 2 may be provided every other plurality, as shown in FIG. Like the tire according to the embodiment according to the present invention, the tires may be arranged in all the rows of the block land portions. Further, in FIG. 2 or FIG. 3, the shape of the block land portion 2 when viewed in plan is shown as a quadrangle, but may be appropriately changed to various shapes used in conventional tires.

  The above description shows only a part of the embodiment of the present invention, and these configurations can be combined alternately or various changes can be made without departing from the gist of the present invention.

  Next, the tire of the present invention having the tread pattern shown in FIG. 4 (Example) and the tire having the tread pattern of the prior art tire shown in FIG. This will be described below.

  In the tire of the embodiment having the tread pattern shown in FIG. 4, by arranging four circumferential grooves 3 in the tread portion 1, a central land portion 8 and a shoulder land portion 9 disposed on the outer side in the tire width direction. And an intermediate land portion 10 disposed between the land portions. Further, by arranging a plurality of lateral grooves 4, the shoulder land portion 9 and the intermediate land portion 10 are each divided into a large number of block land portions 2. These block land portions 2 are provided with a plurality of sipes 5 extending so as to intersect the tire circumferential direction. Further, as shown in the figure, the intermediate land portion 10 includes a first groove 6 that terminates in the land portion, and the other facing from the vicinity of one acute angle corner portion of the block land portion 2 in a direction crossing the first groove. The second groove 7 extending toward the vicinity of the acute angle portion and terminating in the land portion is disposed. A plurality of small holes 11 are disposed in the vicinity of the acute angle corner of the intermediate land portion 10.

  In the conventional tire having the tread pattern shown in FIG. 5, instead of the first groove 6 and the second groove 7, the one end of the pair of edge portions is directed to the other in the same direction as the extending direction of the sipe 5. It has a pair of grooves that extend to the end and terminate in the land portion, and basically has the same configuration as the tire of the embodiment except that.

Each of these prototype tires is a 205 / 65R15 passenger car radial tire, and has the following specifications. Negative rate: 28.5% (Example), 27.9% (Conventional example)
Sipe 5 tire circumferential width: 0.4 mm
Groove width of the tire circumferential groove between the central land portion 8 and the intermediate land portion 10: 3.0 mm
The width of the tire circumferential groove between the shoulder land portion 9 and the intermediate land portion 10 is 8.5 mm.
The width of the shoulder land portion 9 in the tire width direction: 28.0 mm
Shoulder land portion 9 tire circumferential width: 30.0 mm
The width of the lateral groove 5 of the shoulder land portion 9: 5.7 mm
The width of the middle land portion 10 in the tire width direction: 33.5 mm
The circumferential width of the intermediate land portion 10 in the tire circumferential direction: 32.0 mm
Groove width of the lateral groove 5 of the intermediate land portion 10: 4.0 mm

In addition, the first groove 6 and the second groove 7 of the tire of the example have the following specifications.
Length of the first groove 6 (at the groove center): 13.0 mm
Groove width of the first groove 6: 2.5 mm
Angle formed by the extending direction of the pair of first grooves 6: 0 °
Angle at which the extending direction of the first groove 6 is inclined with respect to the tire circumferential direction: 45 °
Extending length of the second groove 7: 16.0 mm
Groove width of the second groove 7: 2.5 mm
Angle of the extending direction of the first groove 1 with respect to the extending direction of the second groove 7: 90 °
Small hole 11: 3 each in the vicinity of each acute angle corner, diameter 1.2mm, depth 7.0mm

Each of these test tires is attached to a rim of size 6.0 × 15.0 to form a tire wheel, which is attached to a test car of Toyota ’s Camry Class, and has an air pressure of 230 kPa (relative pressure). The following evaluation was performed by applying the condition that the tire additional load was about 615 kN.
Feeling on snow: A professional driver comprehensively evaluated the braking performance, starting performance, straight running performance, and cornering performance when driving on a snowy road test course.
On-snow braking performance: The braking distance when full braking was performed from a speed of 40 km / h on a pressure snow road surface was measured and evaluated based on the measurement result.
Traction on snow: The time required to travel a distance of 50 meters was measured after the accelerator was fully opened from a stopped state on a test track on a snowy road surface, and the measurement result was evaluated.
Feeling on ice: A professional driver comprehensively evaluated the braking performance, startability, straightness, and cornering on an ice road test course.
Braking on ice: A braking distance was measured when full braking was performed at a speed of 20 km / h on an ice road surface, and the measurement result was evaluated.
Uneven wear resistance: The amount of step wear between adjacent block land portions was evaluated when traveling on a dry road surface for 5000 km in various travel modes.

  Table 1 shows the evaluation results of these tests. In addition, the evaluation result of Table 1 is shown by the index ratio when the tire evaluation result of a conventional example is set to 100, and performance is excellent, so that a numerical value is large.

  As shown in the results in Table 1, the tires of the examples had improved performance on snow, performance on ice, and uneven wear resistance compared to the tires of the conventional examples.

  As is clear from the above description, the present invention provides a pneumatic tire that improves the performance on ice and snow and at the same time improves uneven wear resistance by optimizing the shape of the block land portion. It became possible to do.

It is a perspective view which extracts and shows one of the block land parts shown in FIG. It is a top view of the other typical block land part according to this invention. It is a top view of the other typical block land part according to this invention. FIG. 3 is a development view of a part of a tread portion of a tire according to an embodiment. FIG. 6 is a development view of a part of a tread portion of a conventional tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Block land part 3 Circumferential groove 4 Horizontal groove 5 Sipe 6 First groove 7 Second groove 8 Central land part 9 Shoulder land part 10 Middle land part 11 Small hole

Claims (7)

By arranging a plurality of circumferential grooves extending substantially in the tire circumferential direction and a plurality of lateral grooves communicating with two adjacent circumferential grooves in the tread portion, at least one comprising a plurality of block land portions. In a pneumatic tire formed by partitioning a block land portion row of rows and arranging a plurality of sipes on the block land portion,
At least one of the block land portions extends from one of a pair of opposing edge portions or corner portions toward the other, a first groove terminating in the land portion, and a direction intersecting the first groove, A pneumatic tire characterized in that a second groove having both ends terminating in the land is disposed.   The pneumatic tire according to claim 1, wherein an angle formed by an extending direction of the pair of first grooves is within a range of ± 5 °.   The pneumatic tire according to claim 1 or 2, wherein an angle formed by the extending direction of the first groove and the extending direction of the second groove is in a range of 70 ° to 110 °.   The pneumatic tire according to any one of claims 1 to 3, wherein the block land portion has a pair of acute angle portions and obtuse angle portions, and the first grooves are provided in the acute angle portions.   The said block land part has a pair of acute angle part and obtuse angle part, The said 1st groove | channel is provided in the edge part of the vicinity of the said acute angle part, The Claim 1 characterized by the above-mentioned. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 5, wherein an extending direction of at least one of the first groove and the second groove is inclined with respect to the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 6, wherein an extending direction of at least one of the first groove and the second groove is inclined with respect to an extending direction of the sipe.

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