JP5503884B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which a sipe (narrow groove) is provided on a tread surface to improve the running performance of a vehicle on an icy and snowy road surface.

  Conventionally, a plurality of blocks are formed in the land by providing circumferential grooves extending in the circumferential direction and transverse grooves extending in the width direction on the tread surface, and thin grooves called sipes (thin grooves) are formed in these blocks in the tire width. A pneumatic tire formed along a direction is known (see, for example, Patent Document 1). When this pneumatic tire rolls, the edge, which is the angle of the sipe, scratches snow and ice on the road surface, and the so-called edge effect improves the running performance of the vehicle on the icy and snowy road surface.

JP-A-6-297918

  However, in the conventional pneumatic tire described above, if a large number of sipes are formed in the land portion in order to improve the running performance on snow, the rigidity of the land portion may be lowered and the running stability may be lowered.

  An object of the present invention is to provide a pneumatic tire capable of improving on-snow performance while maintaining high land rigidity when a narrow groove is formed on a tread surface.

  A first feature of the present invention is that a plurality of circumferential grooves (circumferential grooves 10 to 13) extending in the tire circumferential direction are provided in the tread portion (tread portion 5), and a land portion (land) is provided between the circumferential grooves. A pneumatic tire (pneumatic tire 1) in which a plurality of narrow grooves (thin grooves 21 to 25) extending along the tire width direction are formed in the land portion, and the narrow grooves are formed. The gist is that the crossing angles (crossing angles θA to θE) formed with the circumferential direction are set so that the narrow groove on the outer side in the width direction is smaller than the inner side in the width direction.

  As described above, the extending direction of the narrow groove is gradually inclined so as to gradually approach the tire circumferential direction from the inner side to the outer side in the tire width direction. Here, the portion of the land portion on the center side in the tire width direction has a large contribution to driving and braking performance, and a narrow groove having an angle close to a right angle with respect to the tire circumferential direction is arranged to provide an edge effect in the front-rear direction. Is generated efficiently. On the other hand, the outer portion in the tire width direction greatly contributes to the on-snow maneuvering stability performance, and by forming a narrow groove close to the tire circumferential direction, the lateral edge effect is efficiently generated.

  Therefore, with the arrangement structure of narrow grooves as described above, the driving performance, braking performance, and maneuvering when a pneumatic tire is used as a snow tire without increasing the amount of narrow grooves while maintaining high land rigidity are provided. Stable performance can be improved efficiently.

  According to the pneumatic tire of the present invention, when a narrow groove is formed on the tread surface, the performance on snow can be improved while maintaining high land portion rigidity.

1 is a cross-sectional view in the width direction of a pneumatic tire according to an embodiment of the present invention. 2 is a tread pattern according to an embodiment of the present invention. It is a tread pattern which shows the prior art example in an Example.

  Hereinafter, details of a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

<Schematic configuration of pneumatic tire>
FIG. 1 is a cross-sectional view in the width direction of a pneumatic tire according to an embodiment of the present invention.

  The pneumatic tire 1 includes a pair of annular bead cores 2 and 2 that are spaced apart in the tire width direction, a carcass 3 that serves as a skeleton of a tire that connects these bead cores 2 and 2 in a toroidal shape, A belt layer 4 having two layers disposed on a crown portion 3a disposed in the center in the width direction of the carcass 3;

  Further, a crown portion 3 a of the carcass 3, a belt layer 4, and a tread portion 5 made of a tread rubber covering these are formed at the center portion in the width direction of the pneumatic tire 1. Side wall portions 6 and 6 are provided, and a bead portion 7 is formed in the vicinity of the bead core 2 on the inner diameter side of the side wall portion 6. And the said carcass 3 has the folding | returning part 3b which winds the bead core 2 from the tire width direction inner side, and folds back and extends to a radial direction. The belt layer 4 is composed of an inner belt 8 having a large width dimension in the tire width direction and an outer belt 9 disposed on the outer diameter side of the inner belt 8. Further, circumferential grooves 10 and 11 extending in the tire circumferential direction are formed on the surface of the tread portion 5.

<Schematic configuration of tread pattern>
FIG. 2 shows a tread pattern according to an embodiment of the present invention.

  On the tread surface which is the surface of the tread portion 5, circumferential grooves 10, 11, 12, 13 extending in the tire circumferential direction are formed. That is, with respect to the inner side of the mounting, the circumferential groove 10 is arranged on the center side in the tire width direction, and the circumferential groove 11 is formed on the outer side in the width direction. Moreover, the circumferential groove | channel 12 is arrange | positioned in the tire width direction center side about the mounting | wearing outer side, and the circumferential groove | channel 13 is formed in the width direction outer side. In the present embodiment, the left side in FIG. 2 is disposed outside the mounting and the right side is disposed inside the mounting, and the pneumatic tire 1 is mounted on the left side of the vehicle. Further, lateral grooves 14 and 15 are extended along the tire width direction.

  By these circumferential grooves 10 to 13 and the lateral grooves 14 and 15, a block 20 having a rectangular shape in a plan view is defined in the tread portion 5, and a land portion is formed by these blocks 20. Specifically, the land portion is adjacent to the land portion A disposed on the outermost mounting side in the tire width direction and the inner side of the land portion A, and between the circumferential groove 12 and the circumferential groove 13. The land portion B formed and the land portion C disposed between the circumferential groove 10 and the circumferential groove 12 disposed in the center portion in the tire width direction are adjacent to the mounting inner side of the land portion C, and It comprises a land portion D formed between the directional groove 10 and the circumferential groove 11 and a land portion E arranged on the innermost mounting side in the tire width direction.

  Each of these land portions A to E is provided with a plurality of blocks 20, and a plurality of narrow grooves (sipes) are formed in these blocks 20.

  First, for land A, narrow grooves 21 are formed in each block 20. The narrow groove 21 has an intersection angle θA with respect to the tire circumferential direction indicated by a broken line. Next, for land B, narrow grooves 22 are formed in each block 20. The narrow groove 22 has an intersection angle θB with respect to the tire circumferential direction indicated by a broken line. In addition, for the land portion C, the narrow groove 23 is formed in each block 20. The narrow groove 22 has an intersection angle θC with respect to the tire circumferential direction indicated by a broken line. Further, for the land portion D, a narrow groove 24 is formed in each block 20. The narrow groove 22 has an intersection angle θd with respect to the tire circumferential direction indicated by a broken line. For the land portion E, narrow grooves 25 are formed in each block 20. The narrow groove 22 has a crossing angle θe set to the tire circumferential direction indicated by a broken line.

  With respect to these crossing angles θA to θE, a relationship of θA = θE, θB = θD, θC = 90 °> θB = θD> θA = θE is established. That is, in this embodiment, the tread pattern is symmetrical with respect to the width center CL, and the crossing angle with respect to the tire circumferential direction of the narrow grooves 21 to 25 becomes smaller toward the outer land portion in the tire width direction, and the tire It is inclined to approach the circumferential direction.

  Below, the effect by embodiment of this invention is demonstrated.

<Operation effect>
(1) The tread portion 5 is provided with a plurality of circumferential grooves 10 to 13 extending in the tire circumferential direction, the land portions A to E are formed between the circumferential grooves 10 to 13, and the land portions A to E are formed. This is a pneumatic tire 1 in which a plurality of narrow grooves 21 to 25 extending in the tire width direction are formed. The crossing angles θA to θE formed with the circumferential direction of the narrow grooves 10 to 13 are set so that the narrow groove on the outer side in the width direction is smaller than the inner side in the width direction.

  As described above, the extending direction of the narrow groove is gradually inclined so as to gradually approach the tire circumferential direction from the inner side to the outer side in the tire width direction. Here, the portion of the land portion on the center side in the tire width direction has a large contribution to driving and braking performance, and a narrow groove having an angle close to a right angle with respect to the tire circumferential direction is arranged to provide an edge effect in the front-rear direction. Is generated efficiently. On the other hand, the outer portion in the tire width direction greatly contributes to the on-snow maneuvering stability performance, and by forming a narrow groove close to the tire circumferential direction, the lateral edge effect is efficiently generated.

  Therefore, the driving in the case where the pneumatic tire is used as a snow tire while maintaining the high rigidity of the land portion without increasing the amount of the narrow grooves 21 to 25 by the arrangement structure of the narrow grooves 21 to 25 as described above. Performance, braking performance, and steering stability performance can be improved efficiently.

  It should not be understood that the description and the drawings, which form part of the disclosure of the above-described embodiments, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the said embodiment, although the land part was provided in total five places from the land part A to the land part E, six or more places limited to this may be provided, and three places may be sufficient.

  Next, the present invention will be described more specifically through examples.

  A tire having a size of 225 / 45R17 was used as a test tire according to a conventional example and the present invention.

  In the case of the test tire according to the conventional example, a narrow groove 121 is formed in the land portion a and a narrow groove 122 is formed in the land portion b as in the tread pattern of the tread portion 105 shown in FIG. A narrow groove 123 is formed in the portion c, a narrow groove 124 is formed in the land portion d, and a narrow groove 125 is formed in the land portion e. These narrow grooves 121 to 125 all extended along the direction of θ ′ = 90 ° with respect to the tire circumferential direction, that is, along the tire width direction.

  On the other hand, in the case of the sample tire according to the present invention example, it is formed in the tread pattern described in FIG. Here, θA = θE = 30 °, θB = θD = 60 °, and θC = 90 ° were set.

  Regarding the dry vehicle stability, the test tire was mounted on a vehicle, the time was measured on the handling road on the test road surface of the test course, and the reciprocal number was displayed as an index.

  As for the actual snow driving performance on snow, the test tire was mounted on a vehicle, traveled on a test course with a circumference of 3 km, the time required was measured, and the reciprocal number was displayed as an index.

  Furthermore, as for the acceleration performance on snow, the time until the vehicle was started from a stationary state and the speed reached 40 km / h was measured, and the reciprocal number was displayed as an index.

  As for the braking performance on snow, the distance until the vehicle running at a speed of 40 km / h was braked and stopped was measured, and the reciprocal number was displayed as an index. These indexes are all based on the conventional example of 100, and a larger value indicates a better result.

  As shown in Table 1, the pneumatic tire according to the example of the present invention can obtain high performance as compared with the conventional example in all of the dry actual vehicle driving performance, the snow actual vehicle driving performance, the snow acceleration performance, and the snow braking performance. found.

1 Pneumatic tire 10, 11, 12, 13 Circumferential groove 21, 22, 23, 24, 25 Narrow groove

Claims (1)

A pneumatic tire including a tread portion having a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of land portions formed between a pair of circumferential grooves adjacent to each other among the plurality of circumferential grooves. Because
The plurality of land portions include a center land portion provided in the center in the tire width direction, a first outer land portion provided outside the center land portion in the tire width direction, and the first land portion in the tire width direction. Including a second outer land portion provided outside the outer land portion,
The central land portion has a plurality of central narrow grooves,
The first outer land portion has a plurality of first outer narrow grooves,
The second outer land portion has a plurality of second outer narrow grooves,
Said second outer narrow grooves and sharp angles which the and the tire circumferential direction intersecting, less than acute angle between the first outer narrow groove and the tire circumferential direction intersect,
The first outer narrow groove and sharp angles which the and the tire circumferential direction and crossing is smaller than angle the central narrow groove and said tire circumferential direction intersect,
The central narrow groove, the first outer narrow groove, and the second outer narrow groove are stepwise so that the extending direction of the narrow groove approaches the tire circumferential direction from the inner side to the outer side in the tire width direction. A pneumatic tire characterized by being inclined.

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