JP2010247711A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire with residual self-aligning torque ensured for suppressing vehicle drift. <P>SOLUTION: The pneumatic tire 1 comprises a central land part formed with lug grooves 11 and sipes 15 extending along a central belt cord 43 located at a central area in a width direction of the outermost belt 41 placed on a belt layer at the outermost side in diameter. Shoulder land parts have lug grooves 31 and sipes 33, extending in directions intersecting an outside belt cord 45 in mounting and an inside belt cord 47 in mounting at the outermost belt 41 on both sides thereof in the width direction, which have end portions, facing inward in the width direction, are ended in the shoulder land parts. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can ensure residual self-aligning torque.

  Conventionally, a technique for securing residual self-aligning torque by giving directionality to a groove on a tread surface has been developed (see, for example, Patent Document 1).

   The “self-aligning torque” is a force (restoring torque) that works to return the tire to a straight traveling state while the vehicle is traveling. Specifically, during turning of the vehicle, the force applied to the cornering force and the ground contact center point of the tire shift, so a force acts in the direction of decreasing the angle around the ground contact center, but the tire works to return straight ahead. It is a force (torque). Here, the self-aligning torque of the tire itself even when the steering wheel is not cut is called “residual self-aligning torque”.

  The mechanism for generating the residual self-aligning torque will be briefly described with reference to FIG. First, in the tread pattern 101, first to fourth circumferential grooves 3, 5, 7, and 9 are extended along the tire circumferential direction, and a lateral groove 31 extends along the tire width direction on the shoulder land portion. ing. Of the arrows, the white arrow (arrow X) whose outer periphery is a solid line is a lateral force applied to the tread surface during tire rolling, and the arrow (arrow Y) whose outer periphery is a broken line is a longitudinal force generated by the lateral force. The hatched arrows (arrows Z) are rotational moments generated on the tread surface.

  When an automobile equipped with a pneumatic tire having a tread pattern is caused to travel straight, a lateral force acts along the tire width direction as indicated by an arrow X, and a longitudinal force indicated by an arrow Y is generated by the lateral force. A rotational moment indicated by an arrow Z is generated by the lateral force and the longitudinal force of these arrows X and Y. This rotational moment is the residual self-aligning torque.

Japanese Patent Laid-Open No. 7-246806

  However, in the pneumatic tire described in Patent Document 1, both ends in the width direction of the lateral groove disposed in the shoulder land portion are not closed, and so-called both-end openings communicated with the circumferential groove and the ground end. It is a horizontal groove of the type. For this reason, the rigidity of the shoulder land portion is lowered, and it is difficult to secure the residual self-aligning torque. In addition, even if a narrow groove is provided to ensure performance on snow, it is difficult to secure residual self-aligning torque due to a decrease in land rigidity.

  An object of the present invention is to provide a pneumatic tire that can secure a residual self-aligning torque and suppress vehicle flow.

  The first feature of the present invention is that a plurality of circumferential grooves (a first circumferential groove 3, a second circumferential groove 5, a third circumferential groove 7, and a fourth circumferential groove 9) are provided at the center in the tire width direction. A central land portion (the central land portion 21) defined and shoulder land portions (shoulder land portions 23, 25) defined on both sides in the tire width direction; and the central land portion and the shoulder land portion, A transverse groove (lateral groove 31) extending in the tire width direction and a belt layer provided from the tread portion to the shoulder portion, and the transverse groove (lug groove 11, sipe 15) in the central land portion is the largest diameter of the belt layer. The outermost belt (outermost belt 41) arranged on the outer side extends along the belt cord (central belt cord 43) on the center side in the width direction, and the lateral grooves (lateral grooves 31, sipes 33) of the shoulder land portion are In the outermost belt It is configured to extend along a direction intersecting the belt cords on both sides in the direction (the outer belt cord 45 and the inner belt cord 47), and the inner end in the width direction is closed in the shoulder land portion. To do.

  As described above, the lateral groove of the shoulder land portion has the inner end in the width direction closed within the shoulder land portion and is not communicated with the circumferential groove, so that the rigidity of the shoulder land portion is improved. Further, since the lateral groove of the shoulder land portion extends along the direction intersecting the belt cords on both sides in the width direction of the outermost belt, this also improves the rigidity of the shoulder land portion. As described above, the residual self-aligning torque can be effectively ensured.

  In other features, circumferential narrow grooves (circumferential narrow grooves 35, 135, 235) that extend in the tire circumferential direction and intersect the lateral grooves (lateral grooves 31) are formed in the shoulder land portions (shoulder land portions 23, 25). The gist is that the depth (depth D1) of the circumferential narrow groove is set to be shallower than the depth (depth D0) of the lateral groove.

  Another feature of the present invention is that the circumferential narrow grooves (circumferential narrow grooves 35 and 235) are divided and extend intermittently along the tire circumferential direction.

  In another feature, the shoulder land portion (shoulder land portion 23, 25) communicates with at least one of the lateral groove (lateral groove 31) and the circumferential narrow groove (circumferential narrow grooves 35, 135, 235). The gist is that the width direction narrow grooves (width direction narrow grooves 37, 39, 137) extending in the tire width direction are formed.

  According to the pneumatic tire of the present invention, it is possible to secure the residual self-aligning torque and suppress the vehicle flow.

1 is a tread pattern of a pneumatic tire according to a first embodiment of the present invention. It is explanatory drawing which contrasted the tread pattern of FIG. 1 with the belt cord of the outermost belt corresponding to this. It is an enlarged view of the principal part in the tread pattern of FIG. It is sectional drawing by the AA line of FIG. It is a tread pattern of the pneumatic tire by a 2nd embodiment of the present invention. It is an enlarged view which shows the horizontal groove vicinity of the shoulder land part by 3rd Embodiment of this invention. It is an enlarged view which shows the horizontal groove vicinity of the shoulder land part by 4th Embodiment of this invention. It is an enlarged view which shows the horizontal groove vicinity of the shoulder land part by 5th Embodiment of this invention. It is an enlarged view which shows the horizontal groove vicinity of the shoulder land part by 6th Embodiment of this invention. It is a tread pattern of the pneumatic tire by the prior art example in an Example. It is explanatory drawing which shows the generation | occurrence | production mechanism of a residual self-aligning torque.

  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 the actual ones. Accordingly, 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.

[First embodiment]
First, the tread pattern of the pneumatic tire 1 according to the first embodiment of the present invention will be described.

  As shown in FIG. 1, a plurality of circumferential grooves are extended along the tire circumferential direction (hereinafter referred to as “circumferential direction”). Among these, those closest to the tire center are the first circumferential groove 3 and the second circumferential groove 5, and on the outer side of the first circumferential groove 3 in the tire width direction (hereinafter referred to as "width direction"), A third circumferential groove 7 is formed, and a fourth circumferential groove 9 is disposed outside the second circumferential groove 5 in the width direction.

  The first circumferential groove 3 and the third circumferential groove 7 communicate with each other via a lug groove (lateral groove) 11 extending in the width direction, and both the second circumferential groove 2 and the fourth circumferential groove 9 are arranged in the width direction. It communicates via the extending lug groove 13. The first circumferential groove 3 and the second circumferential groove 5 communicate with each other via a sipe 15 extending in the width direction. The lug grooves 11 and 13 and the sipe 15 are inclined in the tire rotation direction side and extend substantially linearly from the inner side to the outer side.

  A space between the third circumferential groove 7 and the fourth circumferential groove 9 is formed in the central land portion 21, which is outside in the width direction than the third circumferential groove 7 and outside in the width direction than the fourth circumferential groove 9. Are formed in the shoulder land portions 23 and 25. In the shoulder land portions 23 and 25, a lateral groove 31, a sipe 33, and a circumferential narrow groove 35 extending in the width direction are formed.

  A belt layer in which a plurality of belts are laminated is disposed from the tread portion to the shoulder portion of the tire, and the outermost belt of the plurality of belts is the outermost belt. As shown in FIG. 2, the outermost belt 41 has a plurality of belt cords extending in the width direction at equal intervals in the circumferential direction. The outermost belt 41 is divided into three in the width direction, and includes a width direction center side, a mounting outer side with respect to the width direction center side, and a mounting inner side with respect to the width direction center side.

  Here, as shown in FIG. 2, the inclination angle of the lug groove 11 and the sipe 15 in the central land portion 21 is θ1 with respect to the width direction, and the inclination angle of the lateral groove 31 and the sipe 33 in the shoulder land portions 23 and 25 is Θ2 and θ3 with respect to the width direction.

  The outermost belt 41 extends in the width direction center side in the same direction as the inclination direction of the lug groove 11 and the sipe 15 in the central land portion 21 of the tread surface (that is, toward the tire rotation direction side from the mounting inner side toward the mounting outer side). A plurality of central belt cords 43 that are inclined) are arranged. Therefore, the inclination angle θ4 with respect to the width direction of the center side belt cord 43 substantially coincides with the inclination angle θ1.

  The outermost belt 41 extends outward in the width direction so as to intersect with the inclination direction of the lateral groove 31 and the sipe 33 in the shoulder land portions 23 and 25 of the tread surface (that is, toward the tire rotation direction side from the mounting inner side toward the mounting outer side). A plurality of mounting outer belt cords 45 and mounting inner belt cords 47 that are inclined) are arranged. The inclination angles of the outer belt cord 45 and the inner belt cord 47 are θ6 and θ5 with respect to the width direction, and both θ5 and 6 and θ2 and 3 described above are set to substantially the same angle. .

  Further, as shown in FIG. 3, a lateral groove 31 is inclined and disposed in the shoulder land portion 23 on the outer side of the third circumferential groove 7. This inclination direction is inclined toward the opposite side of the tire rotation direction from the inner side to the outer side. Further, the end of the lateral groove 31 on the inner side in the width direction is closed within the shoulder land portion 23. In the intermediate portion in the width direction of the lateral groove 31, a circumferential narrow groove 35 extends in the circumferential direction so as to intersect the lateral groove 31, and is substantially parallel to the lateral groove 31 at both circumferential ends of the circumferential narrow groove 35. The 1st width direction narrow groove 37 extended in this is connected. A second width-direction narrow groove 39 that communicates with the third circumferential groove 7 extends substantially parallel to the lateral groove 31 at the inner end in the width direction of the lateral groove 31.

  As shown in FIG. 4, which is a cross-sectional view taken along the line AA in FIG. 3, the depth of the circumferential narrow groove 35 is set to be shallower than the depth of the lateral groove 31. That is, when the groove depth from the tread surface Tr in the lateral groove 31 is D0 and the groove depth from the tread surface Tr in the circumferential narrow groove 35 is D1, the groove depth D1 is set to a depth dimension smaller than D0. ing.

  As shown in FIG. 1, the circumferential narrow grooves 35 disposed in the shoulder land portions 23 and 25 are divided, and one circumferential narrow groove 35 is provided corresponding to one lateral groove 31. And are arranged intermittently along the circumferential direction.

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

<Operation effect>
(1) In the pneumatic tire 1 according to the present embodiment, the lug groove 11 and the sipe 15 of the central land portion 21 are the central belt on the central side in the width direction of the outermost belt 41 disposed on the outermost diameter side of the belt layer. The lateral grooves 31 and sipes 33 of the shoulder land portions 23, 25 extend along the cord 43, and extend along a direction intersecting the mounting outer belt cord 45 and the mounting inner belt cord 47 on both sides in the width direction of the outermost belt 41. The inner end in the width direction is closed within the shoulder land portions 23 and 25.

  As described above, the lateral grooves 31 of the shoulder land portions 23 and 25 have the inner ends in the width direction closed within the shoulder land portions 23 and 25, and are formed in the third circumferential groove 7 or the fourth circumferential groove 9. Since the communication is not established, the rigidity of the shoulder land portions 23 and 25 is improved. Further, since the lateral grooves 31 of the shoulder land portions 23 and 25 extend along the direction intersecting the mounting outer belt cord 45 and the mounting inner belt cord 47 on both sides in the width direction of the outermost belt 41, this also causes the shoulder land The rigidity of the parts 23 and 25 is improved. As described above, the residual self-aligning torque can be effectively ensured.

(2) A circumferential narrow groove 35 extending in the tire circumferential direction and intersecting the lateral groove 31 is formed in the shoulder land portions 23 and 25, and the depth D1 of the circumferential narrow groove 35 is set to be greater than the depth D0 of the lateral groove 31. It is set shallowly.

  By forming the circumferential narrow groove 35, the edge length during tire rolling can be increased, and the performance on snow can be improved. Further, by setting the depth of the circumferential narrow groove 35 to be shallower than that of the lateral groove 31, it is possible to suppress a decrease in rigidity of the shoulder land portions 23 and 25 and to secure a residual self-aligning torque.

(3) Since the circumferential narrow groove 35 is divided and extends intermittently along the tire circumferential direction, it is possible to suppress a decrease in rigidity of the shoulder land portions 23 and 25 and secure a residual self-aligning torque. Can do.

(4) Since the width direction narrow groove 37 that extends in the tire width direction and communicates with the lateral groove 31 and the circumferential direction narrow groove 35 is formed in the shoulder land portions 23 and 25, the land portion rigidity of the shoulder land portions 23 and 25. The residual self-aligning torque can be secured by suppressing the decrease in the above.

[Second Embodiment]
Next, a pneumatic tire according to a second embodiment of the present invention will be described. However, about the same structure as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 5, in the present embodiment, the circumferential narrow grooves 135 disposed in the shoulder land portions 23 and 25 are not divided and are continuously formed along the circumferential direction over the entire tire circumference. . Accordingly, the lateral groove 31 and the first width direction narrow groove 37 extend through the circumferential direction narrow groove 135.

  Also according to the present embodiment, as in the first embodiment, it is possible to suppress the decrease in land portion rigidity of the shoulder land portions 23 and 25 and to secure the residual self-aligning torque.

[Third embodiment]
Next, a pneumatic tire according to a third embodiment of the present invention will be described. However, about the same structure as 1st and 2nd embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 6, in the present embodiment, the position of the circumferential narrow groove 235 is arranged at the inner end in the width direction of the lateral groove 31 as compared with the first embodiment shown in FIG. 3. A second width direction narrow groove 39 extends from the direction narrow groove 235 to the third circumferential groove 7.

  Also according to the present embodiment, it is possible to secure a residual self-aligning torque by suppressing a decrease in land portion rigidity of the shoulder land portions 23 and 25.

[Fourth embodiment]
Next, a pneumatic tire according to a fourth embodiment of the present invention will be described. However, about the same structure as 1st-3rd embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 7, in the present embodiment, the first width direction narrow groove and the second width direction narrow groove are not provided as compared with the first embodiment shown in FIG. That is, the lateral groove 31 and the circumferential narrow groove 35 intersecting with the lateral groove 31 are provided.

  Also according to the present embodiment, it is possible to secure a residual self-aligning torque by suppressing a decrease in land portion rigidity of the shoulder land portions 23 and 25.

[Fifth Embodiment]
Next, a pneumatic tire according to a fifth embodiment of the present invention will be described. However, about the same structure as 1st-4th embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 8, in this embodiment, compared with the first embodiment shown in FIG. 3, the second width direction narrow groove is not provided, and the first width direction narrow groove is outside. An end portion terminates in a circumferential narrow groove to form a second width narrow groove 137.

  Also according to the present embodiment, it is possible to secure a residual self-aligning torque by suppressing a decrease in land portion rigidity of the shoulder land portions 23 and 25.

[Sixth Embodiment]
Next, a pneumatic tire according to a sixth embodiment of the present invention will be described. However, about the same structure as 1st-5th embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 9, in the present embodiment, the first width direction narrow groove is not provided as compared with the first embodiment shown in FIG.

  Also according to the present embodiment, it is possible to secure a residual self-aligning torque by suppressing a decrease in land portion rigidity of the shoulder land portions 23 and 25.

  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.

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

  A pneumatic tire according to a conventional example and Invention Examples 1 and 2 having a size of 265 / 60R18 was used as a test tire. A test tire according to a conventional example was a pneumatic tire 101 having a tread pattern shown in FIG. In the pneumatic tire 101, the lateral groove 131 disposed in the shoulder land portion 23 communicates with the third circumferential groove 7 and the fourth circumferential groove 9.

  The test tire according to Example 1 of the present invention is the pneumatic tire described in the first embodiment (see FIG. 2), and the test tire according to Example 2 of the present invention is the pneumatic tire described in the second embodiment. A tire (see FIG. 5) was obtained.

These test tires were mounted on the rear wheels of an SUV type vehicle. This vehicle is a rear wheel drive type. The results of the running test are shown in Table 1 in the order of acceleration and turning performance among the vehicle flow index and snow performance. Each result is a relative index with the conventional example as a reference value of 100. The vehicle flow index was evaluated by a residual cornering test, and the performance on snow was evaluated by an actual vehicle test.

  As is apparent from Table 1, it was found that Examples 1 and 2 of the present invention were superior to the conventional examples in all of the acceleration and turning characteristics of the vehicle flow index and the performance on snow.

3 First circumferential groove (circumferential groove)
5 Second circumferential groove (circumferential groove)
7 Third circumferential groove (circumferential groove)
9 Fourth circumferential groove (circumferential groove)
11 Lug groove (lateral groove)
15 Sipe (horizontal groove)
21 Central land portion 23, 25 Shoulder land portion 31 Cross groove 41 Outer belt 45 Wearing outer belt cord (belt cord)
47 Wearing inner belt cord (belt cord)

Claims (4)

A central land portion defined on the tire width direction center side by a plurality of circumferential grooves and a shoulder land portion defined on both sides of the tire width direction;
Provided respectively in the central land portion and the shoulder land portion, and provided with a lateral groove extending in the tire width direction, and a belt layer provided from the tread portion to the shoulder portion,
The lateral groove of the central land portion extends along the belt cord on the center side in the width direction of the outermost belt arranged on the outermost diameter side of the belt layer,
The lateral groove of the shoulder land portion extends along a direction intersecting the belt cords on both sides in the width direction of the outermost belt, and is configured so that an end portion on the inner side in the width direction is closed within the shoulder land portion. And pneumatic tires. In the shoulder land portion, a circumferential narrow groove extending in the tire circumferential direction and intersecting the lateral groove is formed,
The pneumatic tire according to claim 1, wherein a depth of the circumferential narrow groove is set to be shallower than a depth of the lateral groove.   The pneumatic tire according to claim 1, wherein the circumferential narrow groove is divided and extends intermittently along the tire circumferential direction.   The width direction narrow groove which is connected to at least any one of the said lateral groove and the said circumferential direction narrow groove, and extends in a tire width direction was formed in the said shoulder land part, The any one of Claims 1-3 characterized by the above-mentioned. The described pneumatic tire.

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