JP4909035B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a plurality of land portion rows along a tire circumferential direction are formed on a tire tread surface portion.

  In the pneumatic tire, various devices have been conventionally made for the tread pattern in order to improve the tire performance (see, for example, Patent Document 1 or 2).

  However, conventionally, there has been a demand for a higher level of compatibility between drainage performance, handling stability, and snowiness.

For this purpose, it is conceivable to change the design and position of the circumferential main groove in the vicinity of the tire center, that is, to improve the drainage efficiency by arranging a straight groove in the tire center to improve the high pre-performance. . However, when a straight groove is disposed in the tire center, there is no land portion in the tire center, and thus there is a problem that steering stability (particularly initial steering performance) on a dry road may be inferior. Moreover, since there is no land edge in the part where the contact length becomes the longest, there is a problem that the drivability (snow on the snow) on the snow road may be inferior.
JP 2003-146016 A JP 2005-53311 A

  In view of the above facts, an object of the present invention is to provide a pneumatic tire in which drainage performance, steering stability, and snowiness properties are compatible at a higher level.

  The present inventor has examined a conventional pneumatic tire. When the center line of the circumferential main groove coincides with the tire equator, or the center line of the circumferential main groove does not coincide with the tire equator, When it was in the vicinity, it paid attention to that the angle of the rib groove wall adjacent to the circumferential main groove was not asymmetrical on both side walls of the circumferential main groove.

Then, by making this asymmetric, it was thought that it would be possible to obtain a tread pattern that does not deteriorate steering stability and snowiness even if a circumferential main groove is disposed in the vicinity of the tire center.
And this inventor repeated examination and experiment, and came to complete this invention.

  The invention according to claim 1 is a pneumatic tire in which a plurality of land portion rows along the tire circumferential direction are formed on a tire tread surface portion, and the center line of the circumferential main groove closest to the tire equator and the tire When the distance from the equator is L and the tread width is TW, L ≠ 0, 0.015 ≦ L / TW ≦ 0.25 is satisfied, and a groove wall on one side of the circumferential main groove is formed to form a tire circumferential direction. And a rib portion that is continuous with each other, and the inclination angles of both groove walls of the circumferential main groove are not the same.

  The width of the tread portion is a distance between tread ends on both sides in the tire width direction. Here, the tread end means that a pneumatic tire is mounted on a standard rim specified in JATMA YEAR BOOK (2004 edition, Japan Automobile Tire Association Standard), and the maximum load in the applicable size and ply rating in JATMA YEAR BOOK. Fills 100% of the air pressure (maximum air pressure) corresponding to the capacity (internal pressure-load capacity correspondence table) as the internal pressure, and indicates the outermost contact portion in the tire width direction when the maximum load capacity is applied. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

  In the invention according to claim 1, in this way, in consideration of drainage, the circumferential main groove is disposed on or near the tire equator, and the center line of the circumferential main groove and the tire equator are Ribs are provided on the tire equator or in the vicinity of the tire equator by shifting the distance L. As a result, it is possible to improve drainage and to ensure steering stability (operability) and snowiness. Therefore, it is possible to provide a pneumatic tire in which drainage performance, steering stability, and snowiness properties are compatible at a higher level than before.

  Further, the rib portion forms a groove wall on one side of the circumferential main groove. And since the inclination angle of both the groove walls of the circumferential main groove is not the same, the tread pattern is an asymmetric pattern. Thereby, it becomes possible to perform functional separation between the groove wall for ensuring rigidity and the groove wall for drainage. Therefore, both drainage and steering stability can be achieved.

  According to a second aspect of the present invention, the sipe formed on the rib portion is configured only by a sipe whose width is closed when a normal internal pressure, 0.8 times the normal load is applied to the tire and contacts the road surface. It is characterized by being.

  Here, the normal load and the normal internal pressure refer to the maximum load and the air pressure corresponding to the maximum load in the applicable size / ply rating defined in the 2004 version YEAR BOOK issued by JATMA. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  According to the second aspect of the invention, the effect of the first aspect of the invention can be further remarkably exhibited.

  The invention according to claim 3 is a straight line that satisfies 0.015 ≦ W / TW ≦ 0.15 and extends substantially in the tire width direction (tire axial direction), where W is the width in the tire width direction of the rib portion. Or a zigzag sipe is formed on the rib portion.

  Extending substantially in the tire width direction means that the inclination angle with respect to the tire width direction is within 45 °.

  The zigzag sipe refers to a sipe in which sipe portions that are inclined with respect to the extending direction of the sipe are folded while being turned in an alternate inclination direction.

  According to the third aspect of the present invention, it is possible to secure a sipe width that can sufficiently exhibit the performance on snow while securing sufficient rigidity even if the sipe is provided.

  The invention according to claim 4 is characterized in that the rib portion is formed at least on the outer side in the tire width direction (that is, on the side far from the tire equator) of the circumferential main groove when the vehicle is mounted.

  When the vehicle has a camber angle between the tire inner side and the tire outer side, the turning radius is shorter on the inner side in the tire width direction than on the outer side in the tire width direction. Accordingly, by providing ribs on the outer side in the tire width direction as in the invention described in claim 4, the difference in the radius of rotation can be absorbed, the rotation becomes smooth, and the vibration riding comfort is improved.

  In the invention according to claim 5, when the inclination angle of the groove wall on one side formed by the rib portion is β, and the inclination angle of the groove wall on the other side facing the groove wall on the one side is α, α> β, 2 ° ≦ α ≦ 30 °, and 0 ° ≦ β ≦ 20 ° are satisfied.

  Thus, by increasing the inclination angle of the groove wall on the inner side in the tire width direction of the circumferential main groove (that is, the side closer to the tire equator) when the vehicle is mounted, the steering stability on the dry road (especially the initial steering performance) ) Can be raised.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the pneumatic tire which made the drainage property, steering stability, and snowiness property compatible in a higher dimension.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. As shown in FIG. 1, a pneumatic tire 10 according to an embodiment of the present invention includes a carcass 12 that includes a cord that extends substantially in a radial direction and whose both ends are folded back by bead cores 11. The carcass 12 is composed of one layer or a plurality of layers.

  A belt layer 14 in which a plurality of belt plies are stacked is embedded on the outer side in the tire radial direction of the crown portion 12 </ b> C of the carcass 12. A tread portion 18 (see FIG. 2) in which a circumferential main groove and a lateral groove are disposed is formed on the outer side of the belt layer 14 in the tire radial direction.

  As shown in FIG. 2, a center main groove 17 is formed in the tread portion 19 of the tread portion 18 in the vicinity of the tire equator CL or on the tire equator CL along the tire circumferential direction. Further, the outer main grooves 22 along the tire circumferential direction are formed on both sides of the tire equator CL at positions close to a quarter point Q of the width of the tread portion 19.

When the distance between the center line ML of the center main groove 17 and the tire equator CL is L, and the tread width (the interval between the tread ends T on both sides in the tire width direction) is TW, L ≠ 0.
0.015 ≦ L / TW ≦ 0.25
Meet the relationship.

  Furthermore, a rib wall 20 is formed on the tread surface portion 19 so as to form a groove wall 16E on the outer side in the tire width direction of the center main groove 17 (the side far from the tire equator CL) and continue in the tire circumferential direction. The inclination angles of both the groove walls of the center main groove 17 are not the same, and the tread pattern is an asymmetric pattern.

  In the present embodiment, the center main groove 17 is disposed on the tire equator CL or in the vicinity of the tire equator CL in consideration of drainage properties in this way. In addition, by shifting the center line ML of the center main groove 17 and the tire equator CL by a distance L that satisfies the above conditions, a rib portion that is continuous in the tire circumferential direction on the tire equator CL or in the vicinity of the tire equator CL. 20 is provided. As a result, it is possible to ensure steering stability (operability) and snowiness without impairing drainage.

  Further, the rib portion 20 forms a groove wall 16 </ b> E on one side of the center main groove 17. And since the inclination angle of both the groove walls of the center main groove 17 is not the same, the tread pattern is an asymmetric pattern.

  Thereby, it becomes possible to perform functional separation between the groove wall for ensuring rigidity and the groove wall for drainage. Therefore, both drainage and steering stability can be achieved.

  Further, the rib portion 20 is thus formed on the outer side in the tire width direction of the center main groove 17 when the vehicle is mounted. When the vehicle has a camber angle between the tire inner side and the tire outer side, the turning radius is shorter on the inner side in the tire width direction than on the outer side in the tire width direction. Therefore, by making the rib portion 20 adjacent to the center main groove 17 as described above, the difference in the radius of rotation can be absorbed, and the rotation becomes smooth and the vibration riding comfort is improved.

In the present embodiment, if the inclination angle of the groove wall 16E is β and the inclination angle of the groove wall 16I on the inner side in the tire width direction facing the groove wall 16E is α,
α> β
2 ° ≦ α ≦ 30 °
0 ° ≦ β ≦ 20 °
Α and β are determined so as to satisfy the above. As described above, by increasing the inclination angle α of the groove wall 16I on the inner side in the tire width direction of the center main groove 17 when the vehicle is mounted, steering stability (especially initial steering performance) on the dry road is improved.

  The rib portion 20 includes a circumferential portion 20M that forms a groove wall 16E and extends in the tire circumferential direction, and a branch portion 20S that branches from the circumferential portion 20M and extends outward in the tire width direction.

  A sipe 24 extending in a zigzag shape in the tire width direction Z is formed in the circumferential direction portion 20M, and a sipe 26 extending in a zigzag shape in the tire width direction Z is also formed in the branch portion 20S. . Each of the sipe 24 and the sipe 26 is configured only by a sipe whose width is closed when the tire is loaded with 0.8 times the normal internal pressure and the normal load and contacts the road surface. As a result, the rigidity required for steering stability can be ensured by contact while securing the performance on snow due to the edge effect.

And the tire width direction width W of the circumferential part 20M is:
0.015 ≦ W / TW ≦ 0.15
It is decided to satisfy. Thereby, even if it has a sipe, the sipe width | variety which can exhibit performance on snow can be ensured, ensuring sufficient rigidity.

  In the present embodiment, an example in which the rib portion 20 in which the branch portion 20S is formed is formed in the tread surface portion 19 is described, but the branch portion 20S is not formed and the rib portion 20 is only the circumferential portion 20M. Even if it comprises, the effect acquired by this embodiment is fully recognized.

<Test example>
In order to confirm the effect of the present invention, the inventor has an example of the pneumatic tire 10 of the above embodiment (hereinafter referred to as a tire of an example) and a pneumatic tire of a conventional example (hereinafter referred to as a tire of a conventional example). ) And a durability test was performed to evaluate the durability.

  In the conventional tire, L / TW = 0 and α = β = 15 °, and in the tire of the example, L / TW = 0.03, α = 10 °, and β = 15 °. Other tire conditions were the same.

  In this test example, the tire size was 195/65 R 15 and the lead frame width was 6J-15. Each tire was mounted on a domestic car, and the tire internal pressure was set to the vehicle specified internal pressure (regular internal pressure defined by JATMA) under a load condition in which 600 N was added to the weight of the driver.

  Further, a) high pre-performance (hydroplaning performance), b) handling stability on a dry road, and c) snowiness were measured for both the conventional tire and the example tire. About the high play performance of a), it evaluated by the generation | occurrence | production speed | velocity at the time of accelerating in the pool of water depth 10mm. The handling stability on the dry road of (b) was evaluated by feeling by a test driver on the dry road. The above-mentioned snow property of c) was evaluated by the time required for reaching 0 km / h to 50 km / h (acceleration time) on the snow, that is, the acceleration property on snow.

表１から判るように、実施例のタイヤでは、従来例のタイヤに比べ、イ）、ロ）、ハ）のいずれについても評価指数が高くなっていた。 In this test example, in performing the performance evaluation, the evaluation index for the conventional tire was set to 100, and the evaluation index for relative evaluation was calculated for the tire of the example. The evaluation results are shown in Table 1. The evaluation results in Table 1 indicate that the higher the evaluation index, the higher the performance.

As can be seen from Table 1, in the tires of the examples, the evaluation index was higher in each of (i), (b), and (c) than in the conventional tire.

  The embodiments of the present invention have been described with reference to the embodiments. However, the above embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

1 is a tire radial direction cross-sectional view of a pneumatic tire according to an embodiment of the present invention. 2A and 2B are a plan view showing a tread portion of a pneumatic tire according to an embodiment of the present invention, and a cross-sectional view taken along line 2B-2B in FIG. .

Explanation of symbols

10 Pneumatic tire 16E Groove wall (groove wall on one side)
16I groove wall (the groove wall on the other side)
17 Center main groove (circumferential main groove)
19 Tread part (tire tread part)
20 Rib part 24 Sipe 26 Sipe CL Tire equator ML Center line

Claims (5)

A pneumatic tire in which a plurality of land portion rows along a tire circumferential direction are formed on a tire tread portion,
When the distance between the center line of the circumferential main groove closest to the tire equator and the tire equator is L, and the tread width is TW,
L ≠ 0
0.015 ≦ L / TW ≦ 0.25
The filling,
Forming a groove wall on one side of the circumferential main groove to form a rib portion continuous in the tire circumferential direction;
A pneumatic tire characterized in that the inclination angles of both groove walls of the circumferential main groove are not the same.   2. The sipe formed on the rib portion is configured only by a sipe whose width is closed when a normal internal pressure and a normal load of 0.8 times are loaded on the tire and contact with the road surface. Pneumatic tire described in 2. When the width in the tire width direction of the rib portion is W,
0.015 ≦ W / TW ≦ 0.15
The filling,
The pneumatic tire according to claim 2, wherein a straight or zigzag sipe extending substantially in the tire width direction is formed in the rib portion.   The pneumatic tire according to claim 3, wherein the rib portion is formed at least on the outer side in the tire width direction of the circumferential main groove when the vehicle is mounted. When the inclination angle of the groove wall on one side formed by the rib portion is β and the inclination angle of the groove wall on the other side facing the groove wall on the one side is α,
α> β
2 ° ≦ α ≦ 30 °
0 ° ≦ β ≦ 20 °
The pneumatic tire according to claim 4, wherein:

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