JP4499467B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which the width of the crossing layer is narrower than the tread width.

  Off-the-road tires used for construction vehicles and the like are required to have much higher load capacity and traction performance than the same heavy-duty tires such as truck and bus tires. For this reason, conventionally, as a tread pattern, ribs that exhibit high wear resistance even at high loads have been formed at the center of the tread, and lugs that exhibit high traction performance have been formed on both sides of the tread. Is used.

  In addition, off-the-road tires for construction vehicles, etc. have two or more belt layers to exhibit wear resistance against high loads, and the width of these belt layers (the width of the main crossing layer) is It was as narrow as 25% to 50% of the tread width.

Conventionally, in such an off-the-road tire, in order to extend the life until the tire is completely worn, in the tread pattern design, the tread gauge is increased or the negative rate of the tread pattern (the area ratio of the groove portion to the tread surface) is reduced. (For example, refer to Patent Documents 1 to 4). Alternatively, the tread rubber has been improved in wear resistance.
International Publication Number WO 02/100664 A1 JP 2001-55017 A JP-A-2-179507 JP 11-198610 A

  However, as described above, off-the-road tires for construction vehicles have a feature that the belt width of the main crossing layer with respect to the tread width is narrow. For this reason, the wear distribution in the width direction of the tread surface is as shown in FIG. That is, wear occurred quickly in the portion of the tread at 1/4 of the tread width from both ends.

  In view of the above problems, an object of the present invention is to provide a pneumatic tire that can improve the wear resistance performance at the ¼ point portion of the tread width and extend the life of the tire.

In order to solve the above problems, the feature of the present invention is that the angle formed with the tire equator line of the coated cord is Ba, the width of the crossing layer which is the overlapping portion of the laminated belt layers is Bw, and the tread width is Tw. A pneumatic tire having a belt layer of 3 ° <Ba <12 ° and 0.25 × Tw <Bw <0.5 × Tw, wherein the tread has a 1 / d from the tire equator line toward the tread end direction. A pair of circumferential grooves in a region M1 of 2 Tw × 20% to 1/2 Tw × 45%, a narrow width portion that opens in the circumferential groove, a narrow width portion that is connected to the narrow width portion, and is closed at the tread end. width will have a and width direction lug main groove comprising a wide wide portion, the narrow portion toward the tire equator line to the tread end direction 1 / 2Tw × 55% ~1 / 2Tw × 80% of the area M2 And the width of the narrow portion is 1 / 2T. The gist is that it is not less than w × 2% and not more than 1 / 2Tw × 3% .

  According to the pneumatic tire according to the feature of the present invention, by providing a circumferential groove in the region M1, and providing a width direction lug main groove having a narrow groove width on the center side and a wide groove width on the shoulder side, a tread width 1/4. The wear resistance performance at the point can be improved. Moreover, high traction performance can be exhibited by providing the width direction lug main groove which consists of a narrow part and a wide part.

  Further, the depth of the circumferential groove in the pneumatic tire according to the feature of the present invention is desirably 60 to 100% of the depth of the width direction lug main groove. Since the circumferential groove has substantially the same depth as the width direction lug main groove, high traction performance can be exhibited both in the front-rear and lateral directions.

  In addition, the width of the circumferential groove in the pneumatic tire according to the feature of the present invention is preferably 1/2 Tw × 2% or more. When the circumferential groove has a certain width or more, it is possible to further improve the wear resistance performance at the tread width 1/4 point portion.

  Further, it is desirable that the narrow portion of the pneumatic tire according to the feature of the present invention exists in a region M2 of 1/2 Tw × 55% to 1/2 Tw × 80% from the tire equator line toward the tread end direction. By providing the narrow portion in the region M2, it is possible to further improve the wear resistance performance at the ¼ point portion of the tread width.

Also, the width of the narrow portion in the pneumatic tire according to the first aspect, 1/2 Tw × 2% or more, and Ru der 1/2 Tw × 3% or less. By defining the width of the narrow portion in this way, the wear resistance performance at the tread width 1/4 point portion can be further improved.

  ADVANTAGE OF THE INVENTION According to this invention, the abrasion resistance performance in a tread width 1/4 point part can be improved, and the pneumatic tire which can extend the lifetime of a tire can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Composition of pneumatic tire)
As shown in FIG. 1, a pneumatic tire 10 according to an embodiment of the present invention includes a pair of bead portions 1 and a pair of sidewall portions 2, and a tread portion 3 continuous in a toroid shape between the sidewall portions 2. Is provided. The carcass 5 is a toroidal radial carcass that reinforces the bead part 1, the sidewall part 2, and the tread part 3 between a pair of bead cores 4 embedded in the bead part 1. The belt layer 6 of the layer or more is arranged, and the tread portion 3 is reinforced. In FIG. 1, three belt layers 6 are laminated.

  FIG. 2 is a plan view of the laminated belt layer 6 in which the belt layer 6 disposed on the innermost side of the tire diameter is developed in the tire circumferential direction and viewed from the tire surface. The belt layer 6 is formed by embedding coated cords 7 (mainly steel cords) extending in parallel with each other at an angle Ba of 3 to 12 ° with respect to the tire equatorial plane in the covering rubber. Moreover, when it sees from the tire surface among the laminated | stacked belt layers, let the overlapping part be a "crossing layer", and let the width be Bw. When the width of the tread in the tire width direction is Tw, the condition of 0.25 × Tw <Bw <0.5 × Tw is satisfied.

  In the present embodiment, the belt layer 6 other than the belt layer 6 disposed on the innermost side of the tire diameter may also have the structure shown in FIG.

  Next, as shown in FIG. 3, the pneumatic tire 10 according to the present embodiment has a pair of circumferential grooves 11 extending in the tire circumferential direction (arrow A direction) and a tire width direction (arrow B direction) in the tread 3. It has the width direction lug main groove 12 extended in this.

  The circumferential groove 11 is arranged in a region M1 of 1/2 Tw × 20% to 1/2 Tw × 45% from the tire equator line CL toward the tread end direction. The depth of the circumferential groove 11 is 60 to 100% of the depth of the width direction lug main groove 12. Further, the width Gw1 of the circumferential groove 11 is ½ Tw × 2% or more.

Further, the width direction lug main groove 12 includes a narrow width portion 12a having a narrow groove width that opens in the circumferential groove 11, and a wide width portion 12b having a wide groove width that is connected to the narrow width portion 12a and closed at the tread end. . The narrow portion 12a exists in a region M2 of 1/2 Tw × 55% to 1/2 Tw × 80% from the tire equator line CL toward the tread end direction. Further, the width Gw2 of the narrow width portion 12a is ½ Tw × 2% or more and ½ Tw × 3 % or less.

(Operation and effect of the pneumatic tire according to the present embodiment)
According to the pneumatic tire according to the present embodiment, the tread includes a pair of 11 circumferential grooves in a region M1 of 1/2 Tw × 20% to 1/2 Tw × 45% from the tire equator line CL toward the tread end direction. It has a narrow-width portion 12a having a narrow groove width that opens to the circumferential groove 11, and a wide-direction lug main groove 12 that is connected to the narrow-width portion 12a and closes at the tread end, and has a wide-width portion 12b having a wide groove width. Thus, a circumferential groove can be provided in the region M1, and a widthwise lug main groove having a narrow groove width on the center side and a wide groove width on the shoulder side can be provided. For this reason, the abrasion resistance performance in the tread width 1/4 point portion can be improved. Moreover, high traction performance can be exhibited by providing the width direction lug main groove which consists of a narrow part and a wide part.

  Moreover, since the depth of the circumferential groove 11 is 60 to 100% of the depth of the width direction lug main groove 12, and is substantially the same depth as the width direction lug main groove 12, both the front and rear and the lateral direction are high. Traction performance can be demonstrated.

  Moreover, since the width Gw1 of the circumferential groove 11 is 1/2 Tw × 2% or more, the circumferential groove has a certain width or more, thereby further improving the wear resistance performance at the 1/4 point portion of the tread width. be able to.

  Further, the narrow width portion 12a of the width direction lug main groove 12 exists in the region M2 of 1/2 Tw × 55% to 1/2 Tw × 80% from the tire equator line CL toward the tread end direction. The wear resistance performance at the ¼ point portion can be improved.

Further, since the width Gw2 of the narrow width portion 12a of the width direction lug main groove 12 is 1/2 Tw × 2% or more and 1/2 Tw × 3 % or less, further wear resistance at the tread width 1/4 point portion. Performance can be improved.

  Examples of the pneumatic tire according to the embodiment of the present invention will be described in detail below. In order to confirm the effect of the present invention, five types of tires according to the examples to which the present invention was applied and one type of conventional tire were mounted on the rim, and the wear resistance performance was evaluated in the field.

In both the example and the conventional example, the tire size was 40.00R57, the rim size was 29 × 6.0, the internal pressure was 7 kg / cm ^2, and a maximum load (60 t) compliant with the TRA standard was applied. Moreover, as an evaluation vehicle, CAT793 was used, and a tire was attached to the front wheel.

  The tires of Examples 1 to 5 and the conventional example have belt layers satisfying 3 ° <Ba <12 ° and 0.25 × Tw <Bw <0.5 × Tw, and have the tread pattern shown in FIG. Test conditions of Examples 1 to 5 and the conventional example (region M1, region M2, circumferential groove width Gw1, narrow portion width Gw2) are as shown in Table 1.

In addition, the wear resistance evaluation is represented by an index with the conventional example being 100, from the both ends of the tread until a certain amount of wear occurs at a portion at 1/4 of the tread width. Was high.

(result)
Table 1 and FIG. 4 show the wear resistance indexes of Examples and Conventional Examples.

  Examples 1-5 have high abrasion resistance compared with a prior art example. Therefore, it was found that wear resistance is improved by setting M1 (Tw / 2) to 20 to 45% and Gw1 / (Tw / 2) to 2% or more.

  Moreover, Example 2 and Example 5 have high abrasion resistance compared with another Example. However, in Example 5, because of failure in the cut separator, wear resistance is improved by setting M2 (Tw / 2) to 55 to 80% and Gw2 / (Tw / 2) to 2 to 6%. I found out that

1 is a cross-sectional view including a tire rotation axis of a pneumatic tire according to an embodiment of the present invention. It is a top view of the belt layer of the pneumatic tire concerning the embodiment of the present invention. It is a top view of the tread of the pneumatic tire concerning the embodiment of the present invention. It is a result of the Example of this invention. It is a wear distribution map on the conventional tread surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bead part 2 ... Side wall part 3 ... Tread part 4 ... Bead core 5 ... Carcass 6 ... Belt layer 7 ... Coated cord 10 ... Pneumatic tire 11 ... Circumferential groove 12 ... Width direction lug main groove 12a ... Narrow width part 12b ... wide part

Claims (3)

3 ° <Ba <12 ° and 0.25 × Tw, where Ba is the angle formed by the coated cord tire equator line, Bw is the width of the crossing layer that is the overlapping part of the laminated belt layers, and Tw is the tread width. A pneumatic tire having a belt layer of <Bw <0.5 × Tw,
In the tread, a pair of circumferential grooves in a region M1 of 1/2 Tw × 20% to 1/2 Tw × 45% from the tire equator line toward the tread end direction,
Open to the circumferential grooves, possess a groove width is narrow narrow portion and closed at the narrow width portion ties tread end, and a width direction lug main groove is a groove width composed of a wide wide portion,
The narrow portion exists in a region M2 of 1/2 Tw × 55% to 1/2 Tw × 80% from the tire equator line toward the tread end direction.
The pneumatic tire according to claim 1, wherein a width of the narrow portion is 1/2 Tw × 2% or more and 1/2 Tw × 3% or less .   2. The pneumatic tire according to claim 1, wherein a depth of the circumferential groove is 60 to 100% of a depth of the widthwise lug main groove.   The pneumatic tire according to claim 1 or 2, wherein a width of the circumferential groove is 1/2 Tw x 2% or more.

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