JP2011068210A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel pneumatic tire improved in performance on snow without deteriorating hydroplaning performance. <P>SOLUTION: The pneumatic tire includes a tread pattern including: a plurality of circumferential grooves provided along the circumferential direction of the tire; lug grooves 4 provided in the direction crossing these circumferential grooves; and a plurality of blocks 5 formed by these lug grooves 4 and the circumferential grooves. Each of the lug grooves 4 has a first groove portion 4a forming an apex 4a<SB>1</SB>by turning back so as to form a V-shape; and a second groove portion 4b connecting to at least a side of the first groove portion 4a and forming an apex 4b<SB>1</SB>by turning back in the direction opposite to the first groove portion 4a so as to form an inverted V-shape. The first groove portion 4a is positioned between two circumferential grooves 2 on both sides of and the nearest to the tire equator among the circumferential grooves. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire that can be used comfortably for an automobile traveling on a snowy road, and more particularly to a pneumatic tire that has improved performance on snow without impairing hydroplaning performance.

Conventionally, in a pneumatic tire for winter, when running on a snowy road, the tire slips without being able to grip the snowy road. As shown in FIG. 1, the traction and braking mechanisms on the snow are as follows: compression resistance F _A , which serves as running resistance on the front surface of the tire, snow column shear force F _{B on the} groove, surface friction force F _C on the block surface, sipe edge It can be classified into edge effect F _D of the block edges. In order to improve on-snow performance such as acceleration and braking performance when starting on a snowy road, it is effective to increase the snow column shear force F _B by providing lug grooves in the tire, but the negative rate (tread contact area) If the lug groove is increased while increasing the ratio of the area of the part such as the groove that is not actually grounded), the rigidity of the block decreases and the steering stability on the paved road deteriorates, On the other hand, when the lug groove is increased without increasing the negative rate, there is a problem that the hydroplaning performance is impaired because the circumferential groove is decreased. Further, in order to improve the hydroplaning performance, the lug groove is V-shaped or streamlined as in, for example, Patent Document 1 (the central portion of the tire width is increased in parallel with the circumferential groove by increasing the lug groove angle, While also been studied that the outward groove perpendicular to close shape peripheral), reduced snow column shearing force F _B of the lug groove, there is a particular tendency for acceleration performance on snow deteriorates, There was still room for improvement.

JP 2000-219014 A

  An object of the present invention is to optimize the tread pattern and improve the performance on snow (acceleration performance on the snow, braking performance, steering stability performance, etc.) without impairing the hydroplaning performance.

The present invention is a plurality of circumferential grooves provided along the circumferential direction of the tire, lug grooves provided in a direction intersecting the circumferential grooves, and a plurality of blocks formed by the lug grooves and the circumferential grooves, In the pneumatic tire having a tread pattern, the lug groove has a top portion formed by folding, and is connected to at least one side of the first groove portion having a V shape and the first groove portion, A top portion is formed by folding back in the opposite direction with respect to the groove portion, and a second groove portion having an inverted V shape is provided,
The first groove portion is characterized in that, among the circumferential grooves, the tire equator is sandwiched between both sides and is positioned between two circumferential grooves closest to the equator.

  In the tire configured as described above, it is preferable that a top portion of the first groove portion intersects at least one circumferential groove of the circumferential groove.

  The lug groove forms a top portion by turning back, and is connected to at least one side of the first groove portion having a V shape and the first groove portion, and the top portion is formed by turning back in the opposite direction to the first groove portion. And a second groove portion having an inverted V shape, wherein the first groove portion includes two circumferential grooves that sandwich the equator of the tire on both sides and are closest to the equator. Since the lug groove is located in between, the snow column shear force can be increased even near the equator of the tire where the angle of the lug groove is almost parallel to the circumferential groove, improving the performance on snow while maintaining the hydroplaning performance. Can be made.

  Since the top portion of the first groove portion intersects with at least one circumferential groove of the circumferential groove, the drainage performance is not deteriorated even in the vicinity of the equator of the tire, and the hydroplaning performance is not impaired.

It is the figure explaining the generation | occurrence | production mechanism of the traction and brake on snow. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial development view showing a tread pattern of a tire according to an embodiment of a pneumatic tire according to the present invention. It is the figure which showed an example of the tread pattern of the conventional tire, (a) is the partial expanded view of a tread pattern, (b) showed about the motion of the snow in a lag groove at the time of braking, and a snow column shear force It is a figure, (c) is the figure shown about the motion of the snow in a lag groove at the time of acceleration, and a snow column shear force. FIG. 3 is a diagram showing a main part of the pneumatic tire shown in FIG. 2, (a) is a diagram showing snow motion and snow column shear force in a lug groove during acceleration, and (b) is a diagram during braking. It is the figure shown about the motion of the snow in a lug groove | channel, and a snow column shear force in. It is the figure which showed other embodiment of the pneumatic tire according to this invention, and is the partial expanded view which showed the tread pattern of the tire. It is the partial expanded view which showed the tread pattern of the reference | standard tire of an Example.

  Hereinafter, the present invention will be described more specifically with reference to the drawings.

  FIG. 2 is a partial development view showing a tread pattern of a tire according to an embodiment of a pneumatic tire according to the present invention. In the drawing, the vertical direction indicates the tire circumferential direction, and the horizontal direction (direction perpendicular to the equator plane E) indicates the tire width direction. An arrow R indicates the rotation direction of the tire.

  In the figure, 1 is a tread portion of the tire. Although the tire of this embodiment is not illustrated, a radial carcass layer extending in a toroidal shape between a pair of left and right bead cores, at least one belt layer disposed on the radial outer side of the radial carcass layer, and the belt The tire structure according to the custom is provided with a tread rubber disposed on the outer side in the tire radial direction of the layer, and the tread portion 1 of the tire has the tread pattern shown in FIG.

  Reference numerals 2 and 3 denote circumferential grooves extending in the tire circumferential direction. The circumferential grooves 2 are two circumferential grooves which are closest to the tire equator E and sandwich the tire equator E among the circumferential grooves extending in the tire circumferential direction. The circumferential grooves 3 are tires of the circumferential grooves 2. It is a circumferential groove located on the outer side in the width direction. In the illustrated example, the number of the circumferential grooves 3 is two, but they may be further increased.

Reference numeral 4 denotes a lug groove, and a plurality of the lug grooves 4 are arranged in the circumferential direction of the tire. The lug groove 4 forms a top part 4a ₁ by folding, and is connected to a first groove part 4a having a V shape and at least one side of the first groove part 4a, and in a direction opposite to the first groove part 4a. folded to form the top 4b ₁ by the, and the second groove 4b of an inverted V-shape, in communication with the second groove 4b, a third groove 4c extending obliquely toward the outer side in the tire width direction It has. Accordingly, the lug groove 4 is a groove having a zigzag shape in which at least two V-shaped folded groove portions are connected to be opposite to each other in the circumferential direction. The first groove 4 a is located between the circumferential grooves 2.

  Reference numeral 5 denotes a block formed by the circumferential grooves 2 and 3 and the lug groove 4 provided in a direction intersecting with the circumferential grooves. The block 5 includes a plurality of zigzag blocks 5a positioned between the circumferential grooves 2 and a substantially square block 5b positioned between the circumferential grooves 2 and the circumferential grooves 3 along the circumferential direction of the tire. I have.

A tread pattern as shown in FIG. 3 (a), which has a circumferential groove and a lug groove folded back in a V shape at the center in the tire width direction, and includes a block partitioned by the lug groove and the circumferential groove. In the conventional tire, when running on snow, the snow column shear force in the lug groove 14 is generated by the wall of the lug groove 14 pushing the snow and compressing the snow to increase the density. The direction of the column shear force is the normal direction of the lug groove 14. That is, at the time of braking, as shown in FIG. 3B, a snow column shearing force f ₁ is generated toward the V-shaped inner side of the lug groove 14. Therefore, the snow moves towards the top of the lug groove 14 (arrow M ₁ direction), the in the vicinity of the top and snow is compressed density, thereby increasing the shear strength of snow, the circumferential direction of the tire snow pillar shearing force F ₁ is able to generate high. Meanwhile at the time of acceleration, as shown in FIG. 3 (c), the V-shaped outwardly snow column shearing force f ₂ of the lug groove 14 is generated, snow direction (arrow away from the top of the lug grooves 14 motion M ₂ direction), will not be compressed. For this reason, high snow column shear force could not be obtained, and acceleration performance on snow could not be satisfied. On the other hand, in the lug groove 4 according to the present invention, as shown in FIG. 4A, at the time of acceleration, the snow column shearing force f ₃ toward the outside of the second groove portion 4b having an inverted V shape. Will occur. Therefore snow is moved in the direction (arrow M ₃ direction) away from the top 4b ₁ of the second groove, partially and thus toward the top portion 4a ₁ of the first groove. At this time, in the vicinity of the top portion 4a1 of the _first groove portion, the snow also moves from the opposite side, so that the snow is compressed and densified, and a high snow column shear force F in the circumferential direction of the tire is obtained. ₃ can be generated. In braking, as shown in FIG. 4 (b), the snow column shearing force f _4, the second groove towards the top 4b ₁ of the (arrow M ₄ directions) for snow moves, the second in the periphery of the top portion 4b ₁ of the groove, it is possible to generate high snow column shearing force F ₄ in the circumferential direction of the tire.

FIG. 5 is a view showing another embodiment of the pneumatic tire according to the present invention. In this example, there is a central circumferential groove 6 that passes through the top 4a ₁ of the _first groove. This makes it possible to improve drainage even near the center in the tire width direction. In addition, since snow gathers from the both sides of the said 1st groove part 4a across the said center circumferential groove 6 at the time of acceleration, it is densified in the intersection of this center circumferential groove 6 and the 1st groove part 4a. . For this reason, even if the central circumferential groove 6 is provided, the high snow column shear force generated in the circumferential direction of the tire is hardly impaired, but more preferably, the central circumferential groove 6 has a groove width of 2 to 10 mm. It is good to do.

  The first groove portion 4a is preferably arranged so that the second groove portion 4b is disposed on both sides of the first groove portion 4a and further symmetrical with respect to the tire equator E. As a result, the force that the tire receives from the contact surface can be made uniform in the tire width direction. Similarly, the circumferential groove 6 is preferably arranged so as to be symmetric with respect to the tire equator E.

  The angle α formed between the first groove 4a and the tire equator E is preferably 30 ° to 60 ° in order to achieve both the drainage of the tire and the snow column shear force, and the second groove 4b and the tire The angle β with the tire equator E is preferably 30 ° to 60 °. The third groove 4c is preferably inclined so as to gradually become perpendicular to the tire equator E toward the outer side in the tire width direction.

  The at least two V-shaped folded groove portions of the lug groove 4 may be curved at the corners, or instead of the V-shaped folded groove portion, may be a substantially U-shaped folded portion.

  The circumferential groove 3 is preferably wider than the circumferential groove 2 to improve the drainage of the tire. Moreover, it is preferable to arrange the circumferential groove 3 in a shoulder portion where the angle of the lug groove 4 is a low angle (an angle close to a right angle with the tire equator E) to improve the drainage performance of the tire.

  Since the compression of snow is high at the center portion in the tire width direction, in order to obtain a higher snow column shearing force, the second groove portion 4b is preferably located near the center portion in the tire width direction, More preferably, it is located between the circumferential grooves 2.

  Moreover, although illustration is abbreviate | omitted to the block 5a and the block 5b, an edge effect can be given by adding a sipe and the performance on snow can be improved. It is desirable to place a plurality of sipes per block, and in order to maintain the rigidity of the block, it is desirable to employ 3D sipes bent in the sipe depth direction in which the sipe walls contact each other during deformation.

  The tire size is 195 / 65R15, and the dimensional relationship shown in Table 1 is applied. The tires 1 to 3 that become the tread pattern shown in FIG. 5 and the reference tire that becomes the tread pattern shown in FIG. We investigated on snow performance and hydroplaning performance.

  About each said tire, it attaches to a rim of size 6Jx15 prescribed | regulated to JATMA YEAR BOOK 2008 (Japan Automobile Tires Association), attaches to a passenger car with an internal pressure of 200 kPa, and on-snow evaluation, on-snow acceleration performance test, on-snow braking performance test, on on snow A steering stability performance test was performed, and a hydroplaning generation speed test was performed as a hydroplaning performance evaluation.

  The on-snow acceleration performance test was evaluated based on the time (acceleration time) required to travel 50 meters from the last time the accelerator was in a stationary state. The results are shown as an index in Table 1 with the time of the reference tire as 100. Larger numbers indicate better performance.

  The on-snow braking performance test was evaluated based on the braking distance when the passenger car braked from an initial speed of 40 km / h. The results are shown in Table 1 as an index, assuming that the braking distance of the reference tire is 100. Larger numbers indicate better performance.

  The snow driving stability performance test was evaluated using a feeling score when a test driver drove a passenger car on the snow test course. The results are shown in Table 1 with an index of 100 for the reference tire. Larger numbers indicate better performance.

  The hydroplaning generation speed test was evaluated by a test driver entering a passenger car at a water depth of 10 mm at different speeds. The results are shown as an index in Table 1 with the speed of the reference tire set to 100. Larger numbers indicate better performance.

  As a result, compared with the reference tire having the conventional tread pattern, the conforming tires 1 to 3 according to the present invention exceed the reference tire in the snow acceleration performance test, the snow braking performance test, and the snow maneuvering stability performance test. The planing generation speed test was confirmed to be equivalent to or better than that of the reference tire.

  According to the present invention, by optimizing the tread pattern, it is possible to improve on-snow performance without impairing the hydroplaning performance, and a new pneumatic tire can be stably supplied.

Reference Signs List 1 tread portion 2 circumferential groove 3 circumferential groove 4 lug groove 4a first groove portion 4b second groove portion 4c third groove portion 5 block 6 central circumferential groove E tire equator

Claims (2)

A tread comprising a plurality of circumferential grooves provided along the circumferential direction of the tire, a lug groove provided in a direction crossing the circumferential groove, and a plurality of blocks formed by the lug grooves and the circumferential grooves In the pneumatic tire to be a pattern, the lug groove is formed by turning back to form a top portion, connected to at least one side of the first groove portion having a V shape and opposite to the first groove portion. A top portion is formed by folding in a direction, and a second groove portion having an inverted V shape is provided,
The pneumatic tire according to claim 1, wherein the first groove portion is located between two circumferential grooves that sandwich the equator of the tire on both sides and are closest to the equator among the circumferential grooves.   The pneumatic tire according to claim 1, wherein a top portion of the first groove portion intersects with at least one circumferential groove of the circumferential groove.

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