JP5277772B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire provided with four main grooves extending in the tire circumferential direction in a tread portion, and more particularly to a pneumatic tire capable of improving steering stability and drainage performance in a balanced manner. .

  The pneumatic tire includes a plurality of main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction in the tread portion. In such a pneumatic tire, when the groove area ratio of the tread portion is increased, the drainage performance is improved, but the steering stability tends to be lowered due to the decrease in the tread rigidity. Therefore, it is difficult to improve the steering stability and the drainage performance in a balanced manner.

  Here, in a pneumatic tire provided with a plurality of main grooves extending in the tire circumferential direction in the tread portion, the center land portion located on the tire equator line is extended while curving in an arc from the main groove on one side. Providing a plurality of arc-shaped grooves crossing the tire equator line and arranging each arc-shaped groove so as to intersect the adjacent arc-shaped grooves can improve steering stability and drainage performance in a well-balanced manner. It has been proposed (see, for example, Patent Document 1).

However, with such a tread pattern, the drainage performance is not always sufficient, and in order to obtain further drainage performance, if the groove component in the tire width direction represented by the lug groove is increased, the steering stability is lowered accordingly. It will be.
JP 2008-6987 A

  An object of the present invention is to provide a pneumatic tire capable of improving steering stability and drainage performance in a well-balanced manner.

In order to achieve the above object, the pneumatic tire of the present invention has two main tires extending in the tire circumferential direction on both sides of the tire equator line in the tread portion, with the tire front and back mounting directions specified when the vehicle is mounted. In the pneumatic tire which provided the groove and divided the land part of five rows by these main grooves,
The center land located on the tire equator line is provided with a plurality of arc-shaped grooves extending from the main groove on one side while curving in an arc shape and crossing the tire equator line, and the tip of each arc-shaped groove is connected to the adjacent circle. In addition to communicating with the arc-shaped groove, the width of the center land portion is set to 20% to 30% of the ground contact width, and each arc surrounded by the arc-shaped groove and the main groove in the center land portion from the main groove to the arc shape A lug groove that extends along the groove and reaches the tire equator line is provided, the end of the lug groove is terminated in the block, and each block surrounded by the arc-shaped groove and the main groove in the center land portion is provided. Providing a sipe communicating with the arcuate groove;
A plurality of bent grooves and tires that extend in the tire width direction from the main groove on one side and bend in the tire circumferential direction in the land between two main grooves that are outside the vehicle when mounted on the vehicle A plurality of sipes extending in the width direction are alternately arranged along the tire circumferential direction , the ends of the respective bending grooves are terminated in the land portion, and the inclination angle θa of the bending groove in the width direction with respect to the tire circumferential direction Is set to 60 ° to 80 °, the inclination angle θb of the circumferential extension of the bent groove with respect to the tire circumferential direction is set to 10 ° to 30 °, and the difference between the inclination angle θa and the inclination angle θb is set to 50 ° or more. In the land portion sandwiched between two main grooves that are outside the vehicle when mounted, the circumferentially extending portion of the bent groove and the sipe intersect each other .

  In the present invention, in addition to providing four main grooves extending in the tire circumferential direction in the tread portion, a plurality of arc-shaped grooves are provided in the center land portion, and the two main grooves that are outside the vehicle when the vehicle is mounted are provided. By providing a plurality of bent grooves in the sandwiched land portion, excellent drainage performance can be exhibited based on these arc-shaped grooves and bent grooves. In addition, neither the arc-shaped groove nor the bent groove divides the land portion in the tire circumferential direction, and sufficiently secures the rigidity of the land portion, so that good steering stability can be maintained. Therefore, steering stability and drainage performance can be improved with a good balance.

  Furthermore, in the present invention, since the arc-shaped groove and the bent groove do not divide the land portion in the tire circumferential direction, the occurrence of heel and toe wear is suppressed, and further, the pattern noise caused by the heel and toe wear is reduced. Can be suppressed.

In the present invention, the width of the center land portion is 20% to 30% of the ground contact width . By providing a plurality of arc-shaped grooves in the wide center land portion, the steering stability and drainage performance can be further improved. Here, the contact width is a dimension in the tire axial direction of the contact area formed under the measurement condition of the tire static load radius determined by the standard on which the tire is based.

Each block surrounded by the arc-shaped groove and the main groove in the center land portion is provided with a lug groove extending from the main groove along the arc-shaped groove, and the tip of the lug groove is terminated in the block . Thereby, drainage performance can be further improved without substantially reducing the steering stability. Each block surrounded by the arc-shaped groove and the main groove in the center land portion is provided with a sipe communicating with the arc-shaped groove . Thereby, it is possible to improve the steering stability particularly on the wet road surface. When the depth of the arc-shaped groove is made shallower toward the tip side, the rigidity of the land portion can be increased, and the steering stability especially on the dry road surface can be improved.

The inclination angle of the circumferentially extending portion of the bent groove with respect to the tire circumferential direction is 10 ° to 30 ° . Thereby, steering stability and drainage performance can be improved with good balance. When the depth of the bent groove is made shallower toward the tip side, the rigidity of the land portion can be increased, and the steering stability especially on the dry road surface can be improved. Bending grooves and sipes are alternately arranged in the tire circumferential direction in a land portion sandwiched between two main grooves that are outside the vehicle when the vehicle is mounted . Thereby, it is possible to improve the steering stability particularly on the wet road surface.

  It is preferable that all of the five rows of land portions divided into tread portions have a rib structure substantially continuous in the tire circumferential direction. Thereby, favorable steering stability can be ensured. The substantially continuous rib structure means a structure that does not include a portion in which the land portion is completely divided in the tire circumferential direction by a groove exceeding 2.0 mm, but is a groove having a groove width of 2.0 mm or less. Splitting is acceptable.

  In the present invention, the main groove is a groove provided with a tread wear indicator (JIS D4230), and the arc-shaped groove, the bent groove, and the lug groove have a groove width of more than 2.0 mm and are narrower than the main groove. The sipe is a groove having a groove width of 0.5 mm to 2.0 mm.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a tread pattern of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 shows an enlarged bent groove. The pneumatic tire of the present embodiment is designated with the tire front and back mounting orientation when the vehicle is mounted, and the vehicle outer side is indicated by OUT and the vehicle inner side is indicated by IN.

  As shown in FIG. 1, four main grooves 1, 2, 3, 4 extending in the tire circumferential direction are sequentially formed in the tread portion T from the vehicle inner side to the vehicle outer side, and these main grooves 1 to 4 form five rows. Land portions 10, 20, 30, 40, and 50 are partitioned. That is, the land portion 10 is located at the shoulder portion inside the vehicle, the land portion 20 is located between the main grooves 1 and 2, the land portion 30 is located between the main grooves 2 and 3, and the land portion 40 is located in the main groove 3. , 4 and the land portion 50 is located at the shoulder portion outside the vehicle.

  A plurality of lug grooves 11 extending in the tire width direction and a plurality of sipes 12 extending in the tire width direction are alternately arranged along the tire circumferential direction on the land portion 10 located on the most shoulder side inside the vehicle. Yes. One end of the lug groove 11 extends to the outside of the ground end, the other end terminates in the land portion 10, and is not in communication with the main groove 1. One end of the sipe 12 terminates in the land portion 10 and the other end communicates with the main groove 1.

  A plurality of lug grooves 21 extending in the tire width direction and a plurality of sipes 22 extending in the tire width direction are provided on the land portion 20 sandwiched between the two main grooves 1 and 2 that are inside the vehicle when the vehicle is mounted. Alternatingly arranged along the direction. One end of the lug groove 21 communicates with the main groove 1 inside the vehicle, the other end terminates in the land portion 20, and is not in communication with the main groove 2. The sipe 22 is disposed so as to cross the land portion 20.

  The center land portion 30 located on the tire equator line E is formed with a plurality of arc-shaped grooves 31 extending from the main groove 2 inside the vehicle while curving in an arc shape and crossing the tire equator line E. . Each arcuate groove 31 is arranged so that the tip thereof communicates with the adjacent arcuate groove 31. The depth of the arc-shaped grooves 31 is shallower toward the tip side and deeper toward the opening end side of the main groove 2. Thus, the center land portion 30 is divided into one rib 30a continuous in the tire circumferential direction and a plurality of blocks 30b surrounded by the arc-shaped groove 31 and the main groove 1b.

  In the center land portion 30, a lug groove 32 extending from the main groove 2 along the arc-shaped groove 31 is formed in each block 30 b surrounded by the arc-shaped groove 31 and the main groove 2. The end of the lug groove 32 terminates in the block 30b. In addition, a plurality of sipes 33 are formed in each block 30b so as to intersect the arc-shaped groove 31.

  The land portion 40 sandwiched between the two main grooves 3 and 4 on the vehicle outer side when the vehicle is mounted extends from the main groove 4 on the vehicle outer side in the tire width direction and bends in the tire circumferential direction in the middle. A plurality of bent grooves 41 and a plurality of sipes 42 extending in the tire width direction are alternately arranged along the tire circumferential direction. Each bent groove 41 has a tip that terminates in the land portion 40 and is not in communication with the main groove 3. The depth of these bent grooves 41 is shallower toward the tip side and deeper toward the opening end side to the main groove 4. On the other hand, the sipe 42 is disposed so as to cross the land portion 40 and intersect the bent groove 41.

  A plurality of lug grooves 51 extending in the tire width direction and a plurality of sipes 52 extending in the tire width direction are alternately arranged along the tire circumferential direction on the land portion 50 located on the most shoulder side on the vehicle outer side. Yes. One end of the lug groove 51 extends to the outside of the ground contact end, the other end terminates in the land portion 50, and is not in communication with the main groove 4. One end of the sipe 52 terminates in the land portion 50, and the other end communicates with the main groove 4.

  In the pneumatic tire having the above-described tread pattern, since the four main grooves 1 to 4 extending in the tire circumferential direction are provided in the tread portion T, occurrence of a hydroplaning phenomenon on a wet road surface can be suppressed. In addition, a plurality of arc-shaped grooves 31 are provided in the center land portion 30, and a plurality of bent grooves 41 are provided in the land portion 40 sandwiched between the two main grooves 3 and 4 that are outside the vehicle when the vehicle is mounted. Therefore, excellent drainage performance can be exhibited based on the arc-shaped groove 31 and the bent groove 41. Further, not only the land portion 30 including the arc-shaped groove 31 and the land portion 40 including the bent groove 41, but all the land portions 10 to 50 including the other land portions 10, 20, and 50 are substantially disposed in the tire circumferential direction. Since the rib structure is continuous and the rigidity of these land portions 10 to 50 is sufficiently secured, good steering stability can be exhibited. Therefore, steering stability and drainage performance can be improved with a good balance.

  Regarding the land portion 40 including the center land portion 30 including the arc-shaped groove 31 and the land groove 40 including the bent groove 41, the arc-shaped groove 31 and the bent groove 41 do not divide the land portions 30 and 40 in the tire circumferential direction. Generation of toe wear can be suppressed, and further deterioration of pattern noise due to heel and toe wear can be suppressed.

  In the pneumatic tire, as shown in FIG. 1, the width W of the center land portion 30 is set in a range of 20% to 30% of the ground contact width GCW. By providing a plurality of arc-shaped grooves 31 with respect to such a wide center land portion 30, it is possible to further enhance the effect of improving steering stability and drainage performance. When the width W of the center land portion 30 is less than 20% of the ground contact width GCW, the steering stability is lowered. Conversely, when the width W exceeds 30% of the ground contact width GCW, a hydroplaning phenomenon is likely to occur on the wet road surface.

  In the pneumatic tire, each block 30a of the center land portion 30 is provided with a lug groove 32 extending from the main groove 2 along the arc-shaped groove 31, and the end of the lug groove 32 is terminated in the block 31. The drainage performance can be further improved without substantially reducing the steering stability. Further, since each block 30a is provided with a sipe 32 that communicates with the arc-shaped groove 31, it is possible to improve steering stability especially on a wet road surface. Furthermore, since the depth of the arc-shaped groove 31 is made shallower toward the tip side, the rigidity of the center land portion 30 can be increased, and the steering stability especially on the dry road surface can be improved. The depth of the arc-shaped groove 31 may be, for example, 6.0 mm to 8.0 mm at the deepest part and 1.0 mm to 3.0 mm at the shallowest part.

  In the pneumatic tire, as shown in FIG. 2, the bent groove 41 is composed of a width direction extension portion 41a and a circumferential direction extension portion 41b. The inclination angle θa of the width direction extension portion 41a with respect to the tire circumferential direction is set in a range of 60 ° to 80 °, while the inclination angle θb of the circumferential direction extension portion 41b with respect to the tire circumferential direction is 10 ° to The range is set to 30 °. More preferably, the difference between the inclination angle θa and the inclination angle θb is 50 ° or more. Thereby, steering stability and drainage performance can be improved with good balance. If the inclination angle θb of the circumferentially extending portion 41b with respect to the tire circumferential direction is less than 10 °, a good drainage channel cannot be formed. Conversely, if it exceeds 30 °, the effect of increasing the groove length is insufficient. Become. Furthermore, by making the depth of the bent groove 41 shallower toward the tip side, the rigidity of the land portion 40 can be increased, and the steering stability especially on the dry road surface can be improved. The depth of the bent groove 41 may be, for example, 6.0 mm to 8.0 mm at the deepest part and 1.0 mm to 2.0 mm at the shallowest part.

  In the pneumatic tire, the bent groove 41 and the sipe 42 are alternately arranged in the tire circumferential direction in the land portion 40 sandwiched between the two main grooves 3 and 4 that are outside the vehicle when the vehicle is mounted. The handling stability on the road surface can be improved.

3 and 4 show reference examples of tread patterns. FIG. 3 shows a configuration in which the sipe 33 is excluded from the center land portion 30 and the sipe 42 is excluded from the land portion 40. FIG. 4 shows a configuration in which the lug groove 32 and the sipe 33 are excluded from the center land portion 30 and the sipe 42 is excluded from the land portion 40. Also in these forms , it is possible to improve steering stability and drainage performance in a well-balanced manner.

Pneumatic tires (Example 1 , Reference Examples 1 and 2 ) having a tire size of 215 / 60R16 and having a tread pattern shown in FIGS. 1, 3, and 4 were produced. In the tires of Example 1 and Reference Examples 1 and 2 , the width of the center land portion is 25% of the ground contact width, the depth of the arc-shaped groove and the bent groove is made shallower toward the tip side, and the circumferential extension of the bent groove The inclination angle with respect to the tire circumferential direction was set to 75 °.

  For comparison, as shown in FIG. 5, four main grooves extending in the tire circumferential direction are provided in the tread portion, and five rows of land portions are partitioned by these main grooves, and a plurality of curved grooves are formed in the center land portion. A pneumatic tire (conventional example) was prepared in which other land portions were partitioned into a plurality of blocks by a plurality of lug grooves extending in the tire width direction.

  These tires were evaluated for steering stability and uneven wear resistance on dry and wet road surfaces by the following evaluation methods, and the results are shown in Table 1.

Steering stability:
The test tire was assembled on a wheel having a rim size of 16 × 6.5 J and mounted on a vehicle having a displacement of 2000 cc. The air pressure was 200 kPa, and the steering stability was subjected to sensory evaluation on a dry road surface and a wet road surface. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the steering stability.

Uneven wear resistance:
The test tire was assembled on a wheel with a rim size of 16 × 6.5 J and mounted on a vehicle with a displacement of 2000 cc, and the amount of uneven wear after traveling 20,000 km was measured with an air pressure of 200 kPa. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the uneven wear resistance.

As is clear from Table 1, the tire of Example 1 was superior in steering stability on the dry road surface and the wet road surface as compared with the conventional example, and also had good results on uneven wear resistance.

It is an expanded view which shows the tread pattern of the pneumatic tire which consists of embodiment of this invention. It is a top view which expands and shows the bending groove | channel in FIG. It is an expanded view which shows the reference example of the tread pattern of the pneumatic tire which concerns on this invention. It is an expanded view which shows the other reference example of the tread pattern of the pneumatic tire which concerns on this invention. It is an expanded view which shows an example of the tread pattern of the conventional pneumatic tire.

Explanation of symbols

1, 2, 3, 4 Main groove 10, 20, 30, 40, 50 Land portion 11, 21, 32, 51 Lug groove 12, 22, 33, 42, 52 Sipe 30a Rib 30b Block 31 Arc-shaped groove 41 Bending groove 41a Width direction extension part 41b Circumferential direction extension part T Tread part

Claims (4)

The orientation of the tire front and back when the vehicle is mounted is specified, and two main grooves extending in the tire circumferential direction are provided on both sides of the tire equator line in the tread portion, and five land portions are defined by these main grooves. In a pneumatic tire
The center land located on the tire equator line is provided with a plurality of arc-shaped grooves extending from the main groove on one side while curving in an arc shape and crossing the tire equator line, and the tip of each arc-shaped groove is connected to the adjacent circle. In addition to communicating with the arc-shaped groove, the width of the center land portion is set to 20% to 30% of the ground contact width, and each arc surrounded by the arc-shaped groove and the main groove in the center land portion from the main groove to the arc shape A lug groove that extends along the groove and reaches the tire equator line is provided, the end of the lug groove is terminated in the block, and each block surrounded by the arc-shaped groove and the main groove in the center land portion is provided. Providing a sipe communicating with the arcuate groove;
A plurality of bent grooves and tires that extend in the tire width direction from the main groove on one side and bend in the tire circumferential direction in the land between two main grooves that are outside the vehicle when mounted on the vehicle A plurality of sipes extending in the width direction are alternately arranged along the tire circumferential direction , the ends of the respective bending grooves are terminated in the land portion, and the inclination angle θa of the bending groove in the width direction with respect to the tire circumferential direction Is set to 60 ° to 80 °, the inclination angle θb of the circumferential extension of the bent groove with respect to the tire circumferential direction is set to 10 ° to 30 °, and the difference between the inclination angle θa and the inclination angle θb is set to 50 ° or more. A pneumatic tire characterized in that a circumferentially extending portion of the bent groove and the sipe intersect each other in a land portion sandwiched between two main grooves that are outside the vehicle when mounted . The pneumatic tire according to claim 1 , wherein the depth of the arc-shaped groove is made shallower toward the tip side. The pneumatic tire according to any one of claims 1-2, characterized in that the shallow depth of the curved groove as the distal end side. The pneumatic tire according to any one of claims 1 to 3 , wherein the five rows of land portions have a rib structure substantially continuous in the tire circumferential direction.

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