JP2010095092A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire capable of extending its life-span by restraining the occurrence of uneven wear, while restraining the chances of catching gravels. <P>SOLUTION: With regard to the tire having grooves, on the surface of its tread, in a direction crossing the equator of the tire extending via at least one bent part, the grooves being oriented in the width direction of the tire, the groove oriented in the width direction of the tire has at least one protrusion provided on the bottom of the groove at the bent portion. In the pneumatic tire, it is preferable that: the protrusion comes in stepwise contact with either of the two walls of the groove at the bent portion; the protrusions are provided in plurality in number toward the bent portion in the groove; the protrusions are placed in alignment in a direction in which the groove in the width direction of the tire extends while these protrusions alternately come in stepwise contact with the walls of the groove. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire, and more particularly to a tire that suppresses the occurrence of stone biting.

  If the vehicle continues to run with stones biting into the tire grooves, the stones that enter can penetrate the groove bottom and reach the belt, leading to premature tire failure. Accordingly, there is a demand for tires that are difficult to bite in the market.

  Regarding the technique for preventing this stone biting, Patent Document 1 discloses that a lug groove is formed from the center side of the tread portion of the tire to the left and right shoulder portions, and a protrusion protruding from the bottom surface is formed on the bottom of the lug groove. A technique for preventing biting is disclosed. By the way, in recent years, uneven wear of tires has been suppressed, and in particular, wear in the vicinity of a point at a distance of 1/4 of the entire width of the tread from the tire equator is caused by slipping in the tire width direction that is likely to occur when the front wheels of the vehicle are mounted. In order to suppress this, attempts have been made to suppress uneven wear by making the block shape of the block pattern, for example, a trapezoidal shape or a parallelogram shape (see Patent Document 2). In such a tread pattern, the problem of the stone bite is remarkable, and even with the technique of Patent Document 1, the stone bite cannot be sufficiently suppressed.

JP-A-5-286419 JP 2007-83822 A

  Accordingly, an object of the present invention is to provide a tire that suppresses stone biting while suppressing uneven wear and extending its life, particularly in a tire having a trapezoidal or parallelogram block pattern.

  The inventor has intensively investigated the problem of stone biting in the tire having the above block pattern, and in order to shape it into the above trapezoidal shape or parallelogram shaped block shape, a bending portion is formed in the width direction groove partitioning this. As the introduction became unavoidable, it was found that the stone bite was remarkable at the bent portion. The inventor has intensively studied a technique for suppressing the stone biting at the bent portion. By forming the groove bottom of the portion having the bent portion into a predetermined shape, the groove of the tire having the block pattern is obtained. The present inventors have found that it is possible to effectively suppress the biting of stones into the body and have completed the present invention.

That is, the gist of the present invention is as follows.
(1) In a tire having a widthwise groove extending through at least one bent portion in a direction crossing the equator of the tire on the surface of the tread, the widthwise groove has at least one protrusion on the groove bottom of the bent portion. The tire characterized by having.

  (2) The tire according to (1), wherein the protruding portion is in contact with either one of both groove walls of the bent portion in a stepped manner.

  (3) The tire according to (1) or (2), wherein the width direction groove has a bent portion in a range of ¼ to 3/8 of the entire width of the tread from the tire equator.

(4) The height h of the protrusion satisfies the following formula, where W is the groove width in the minimum groove width portion of the groove portion where the protrusion is provided, and D is the groove depth. The tire according to any one of (1) to (3).
H> D-1.2W × 1/2 (I)

  (5) The tire according to any one of (1) to (4), wherein a circumferential length of the protrusion is 35 to 45% of the groove width W.

  (6) The tire according to any one of (1) to (5), wherein a length in a width direction of the protrusion is 1.2 to 1.4 times a height h of the protrusion.

  (7) The tire according to any one of (1) to (6), wherein a plurality of the protrusions are provided toward the bent portion of the width direction groove.

  (8) The tire according to (7), wherein the protrusions are arranged in a direction in which the widthwise groove extends, and the protrusions alternately contact the groove wall in a stepped manner.

  (9) The tire according to (7) or (8), wherein an interval between the protrusions is 25 to 35% of a length in the width direction of the protrusions.

  According to the present invention, in a tire having a widthwise groove extending in a direction crossing the tire equator on the tread surface, a protrusion is provided at a bent portion of the widthwise groove, thereby suppressing stone biting into the widthwise groove. Tires can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a partially developed view of an example of a tread of a tire according to the present invention, FIG. 2 is an enlarged view of a portion I in FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA in FIG.

  In an example of the tire tread of the present invention, as shown in FIG. 1, the tread surface has a width direction groove 1 extending through a bent portion 4 in a direction crossing the tire equator, and the width direction groove 1 and the circumferential direction. A tread pattern having a trapezoidal block 2 and a parallelogram block 3 defined by the grooves 7 is provided. Here, in the tire of the present invention, as shown in FIG. 2, it is important that the widthwise groove 1 has a bent portion 4, and at the bent portion 4, at least one protrusion 5 is provided on the groove bottom. It is. As described above, the tire having such a tread pattern reduces the wear near a point that is 1/4 of the entire tread width from the tire equator, which is likely to occur when the tire is mounted on the front wheel of the vehicle, and improves the driving force. However, it is easy to bite the stone at the bent portion 4, and it is difficult to discharge the bitten stone. Therefore, the tire according to the present invention effectively suppresses the stone biting into the widthwise groove by providing the protruding portion 5 at the bent portion, and the stone that has been bitten is easily discharged by the protruding portion. Therefore, the early failure of the tire due to the bite stone as described above can be prevented, and the durability is improved.

Here, as shown in FIG. 2, the bent portion 4 is a distance of 1/16 of the total width of the tread from the straight line extending in the tire circumferential direction at the bending point BP of the width direction groove 1 in the width direction groove 1. The region of a certain width direction groove 1 is indicated. In the bent portion, as shown in the bent portion 4 in FIGS. 1 and 2, at least one of the groove walls of the widthwise groove has a bent point.
Moreover, although the shape of the said protrusion 5 and arrangement | positioning in a groove bottom are not specifically limited, For example, block shapes, such as a rectangular parallelepiped, are mentioned. Furthermore, as shown in FIG. 3, it is preferable that the protruding portion 5 is in contact with any one of both groove walls of the bent portion in a step shape. This is because groove bottom cracks and damage to the protrusion itself can be prevented. For the same reason, it is more preferable that the protrusion 5 is smoothly connected to the groove wall as shown in FIG.

Further, in the present invention, as shown in FIG. 1, the width direction groove 1 communicates with a narrow groove 7 extending in the tread circumferential direction, but is not particularly limited, and any such narrow groove may be provided. Good. Here, in order to maintain the shape of the projections 5, it is preferable Said sub groove 7 is shallower than D ₁ shown in FIG. Moreover, the shape of the width direction groove | channel 1 and the narrow groove 7 is not specifically limited, either.

  By the way, the range from 1/4 to 3/8 of the entire tread width from the tire equator is a portion where the tire is most susceptible to traction, so that stone bites are likely to occur in the grooves. Accordingly, when the bent portion is further provided in such a range, the width direction groove is particularly liable to generate a stone bite. Therefore, when the tire of the present invention has the bent portion 4 in a range of 1/4 to 3/8 of the entire tread width from the tire equator CL as shown in FIG. 2, stone biting can be effectively suppressed. Therefore, it is preferable.

The ease of biting the stone into the groove is almost determined by the cross-sectional shape of the groove and the size of the stone. That is, in principle, the bitestone will slip out by rolling the tire unless it enters below the minimum groove width portion of the groove. Here, it is known from the examination in the present invention that the height of the bitestone is about 1.2 times the width of the bitestone. Therefore, as shown in FIG. 3 which is an AA cross-sectional view (tread circumferential cross-sectional view) of FIG. When the groove depth is D, the protrusions are preferably provided so that the height h of the protrusions 5 satisfies the above formula (I). Because, by providing such a protrusion in the width direction groove, the width direction groove 1 may bite into the width direction groove 1 for the above reason, and the width is about W (about 1.2 W). This is because the stone in the width direction 1 can be prevented from biting. Furthermore, as described above, even if the stone 5 enters the groove, the protrusion 5 also has an action of pushing out the stone from the groove by pressing the stone from the bottom.
Here, the “minimum groove width portion” is intended to be a portion where the inclination of the groove wall of the width direction groove changes as shown by a portion 6 in FIG. It doesn't mean. In the groove on the surface of the tread of the tire, a groove shape in which the inclination of the groove wall changes is common.

Further, in the tire of the present invention, as shown in FIG. 2, the circumferential direction length W ₁ of the protrusion 5 is preferably 35 to 45% of the groove width W ₂ in the width direction groove. Here, the circumferential direction length W ₁ of the protrusion 5, the width direction groove 1 of less than 35% of the groove width W ₂ if the groove bottom insufficient suppression of biting stone for covering areas becomes smaller Therefore, if it exceeds 45%, the volume of the protrusion 5 increases, which causes the heat generation of the tire to increase.
As shown in FIG. 2, the circumferential length W ₁ and the groove width W ₂ of the protrusion 5 are the circumferential length of the protrusion 5 and the width direction groove 1 at the center of the protrusion 5 in the width direction. Width.

Furthermore, in the tire of the present invention, as shown in FIGS. 2 and 3, the width W ₄ of the protrusion 5 is 1.2 to 1.4 times the height h of the protrusion 5. Is preferred. Here, if the length W ₄ in the width direction of the protrusion is less than 1.2 times the height h of the protrusion, the rigidity of the protrusion may not be maintained and the protrusion 5 may be broken from the root. If it exceeds 1.4 times, the heat generation of the tire is deteriorated.

  In the tire of the present invention, a plurality of protrusions 5 are preferably provided per bent portion, and more preferably three or more, in order to efficiently remove bite stones. For the same reason, as shown in FIGS. 1 and 2, the protrusions 5 are preferably provided so as to alternately contact the groove walls in the extending direction of the widthwise grooves. Here, if all the protrusions are in contact with only one groove wall, there is a risk that the suppression of stone biting on the other groove wall side is not sufficient.

In the tire according to the present invention, as shown in FIG. 2, the protrusion 5 has a distance W ₃ between the protrusions 5 adjacent to each other in the tread width direction and 25 to 25 of the width direction length W ₄ of the protrusion 5. It is preferably 35%. Here, the interval W ₃ between the projections adjacent to each other in the tread width direction, the tread width direction of the groove bottom crack is less than 25% of the length W ₄ of the protruding portion becomes easily occurs, with greater than 35% If there is, the area of the groove bottom that appears becomes large and the suppression of stone biting becomes insufficient.

  The tire of the present invention is not particularly limited except that the tread surface has a width direction groove, and the width direction groove is bent in the tread width direction, and has at least one protrusion at the groove bottom. It can be manufactured by a known method using a known tire structure. In addition, the tire of the present invention may be a pneumatic tire or a solid tire. When the tire is a pneumatic tire, the gas filled in the tire may be a normal or an oxygen partial pressure adjusted air. In addition, an inert gas such as nitrogen, argon, or helium can be used.

  The tire of the present invention is suitable as a heavy-duty pneumatic tire, in particular, a construction construction pneumatic tire that is liable to cause stone biting due to use conditions and the like, and that such stone biting greatly deteriorates the durability of the tire.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the scope of the present invention.

(Examples 1-3)
Comparative Examples 1 to 3 use the tread pattern shown in FIG. 5 and Examples 1 to 3 use the tread pattern shown in FIG. 1. Tire size: 46 / 90R57, tire outer diameter: 3578 (mm), belt-shaped tread gauge: 112 (mm) A pneumatic tire was manufactured. Here, in the tread pattern of the pneumatic tire of Example 1, as shown in FIG. 2, the protrusion 5 was provided so as to be in smooth contact with the groove wall in a stepped manner. The tread circumferential cross section of the protrusion 5 has the shape shown in FIG. 3, and W ₁ : 15.6 (mm), W ₂ : 70 (mm), W ₃ : 4 (mm), W ₄ : 14 ( mm), h: 10 (mm), D: 51.6 (mm), and D ₁ : 45.4 (mm), and the three protrusions were provided so as to contact each other alternately between the two groove walls. After assembling these tires to an appropriate rim, an internal pressure of 700 kPa was enclosed. After that, the tire was mounted on a 240 ton dump truck, and a load of 63 ton was applied to run in various places in North America, Asia and Australia. About the tire after driving | running | working, the stone biting rate and the abrasion rate were evaluated by the following method. The results are shown in Table 1.
The stone biting rate is a value calculated from (number of grooves biting stone / number of investigated grooves × 100), and the lower the value, the less stone biting. In addition, the value of the stone biting rate and wear rate of Table 1 shows the average of the evaluation values of each sample.

(Wear rate evaluation method)
The wear rate is determined by measuring the measured groove depth (RTD: Remained Tread Depth) in the treadwear indicator portion of the tire that is actually running, with respect to the original groove depth (OTD: Original Tread Depth), (1 Evaluation was made by calculating -RTD / OTD) x 100 (%).

  From Table 1, it can be seen that the pneumatic tires of Examples 1 to 3 have fewer stone bites than the pneumatic tires of Comparative Examples 1 to 3, respectively.

(Examples 4 to 6)
Further, a pneumatic tire having a tire size of 46 / 90R57, a tire outer diameter of 3578 (mm), and a belt-shaped tread gauge of 112 (mm) and using the tread pattern shown in FIGS. did. After assembling these tires to an appropriate rim, an internal pressure of 700 kPa was enclosed. Thereafter, the tire was mounted on a 240 ton dump truck, and a load of 63 ton was applied to run in North America. About each tire after driving | running | working, the stone biting rate and the abrasion rate were evaluated by the said method. The results are shown in Table 2. In addition, each value of Table 2 is an average of the value which evaluated every 4 samples. Moreover, although the circumferential cross section of the protrusion 5 of FIGS. 6-8 is a shape which is not in contact with a groove wall as shown in FIG. 4, the dimension is the same as that of FIG. 3 except this shape being different.

  From Table 2, the occurrence of stone biting is less in the pneumatic tire of Example 6 in which three protrusions are provided in the bent portion than in the pneumatic tire in Example 5 in which one protrusion is provided in the bent portion. I understand that. Therefore, in the tire of the present invention, it is preferable that a plurality of the protrusions are provided toward the bent portion of the width direction groove. Further, it can be seen that the occurrence of stone biting is less in Example 6 in which the three protrusions are alternately in contact with any one of the groove walls in a staircase pattern than the pneumatic tire of Example 5. Therefore, in the tire of the present invention, the protrusion is in contact with either one of the groove walls of the bent portion in a stepped manner, and the protrusion is aligned in the extending direction of the widthwise groove, and It is preferable that the protrusions alternately contact the groove wall in a stepped manner.

It is a partial development view of an example of the tread of the tire of the present invention. It is an enlarged view of the part of I of FIG. It is AA sectional drawing of FIG. It is AA sectional drawing of FIG. It is a partial expanded view of an example of the tread of a tire. It is a partial expanded view of the other example of the tread of a tire. It is a partial expanded view of the other example of the tread of the tire of this invention. It is a partial expanded view of the other example of the tread of the tire of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Width direction groove | channel 2 Trapezoidal block 3 Parallelogram-shaped block 4 Bending part 5 Protruding part 6 Minimum groove width part 7 Narrow groove 1/8 The point which is 1/8 distance of full width of tread from tire equator A point at a distance of 1/4 of the entire tread width 3/8 A point at a distance of 3/8 of the total tread width from the tire equator BP Bending point CL Tire equator TE Tread edge D The portion where the width of the groove in the width direction is the most narrow Depth h height of protrusion S bite stone W groove width where groove wall slope changes W ₁ circumferential length of protrusion W ₂ groove width W ₃ distance between protrusions W ₄ circumferential direction of protrusion length

Claims (9)

In a tire having a widthwise groove extending through at least one bent portion in a direction crossing the equator of the tire on the surface of the tread,
The widthwise groove has at least one protrusion on the groove bottom of the bent portion.   The tire according to claim 1, wherein the protrusion is in stepped contact with any one of both groove walls of the bent portion.   The tire according to claim 1 or 2, wherein the width direction groove has a bent portion in a range from a tire equator to a distance of 1/4 to 3/8 of a full width of the tread. The height h of the protrusion satisfies the following expression, where W is the groove width in the minimum groove width portion of the groove portion where the protrusion is provided, and D is the groove depth. 4. The tire according to any one of 3.
H> D-1.2W × 1/2 (I)   The tire according to any one of claims 1 to 4, wherein a circumferential length of the protrusion is 35 to 45% of the groove width W.   The tire according to any one of claims 1 to 5, wherein the length in the width direction of the protrusion is 1.2 to 1.4 times the height h of the protrusion.   The tire according to any one of claims 1 to 6, wherein a plurality of the protrusions are provided toward a bent portion of the width direction groove.   The tire according to claim 7, wherein the protrusions are arranged in a direction in which the widthwise grooves extend, and the protrusions alternately contact the groove walls in a stepped manner.   The tire according to claim 7 or 8, wherein the distance between the protrusions is 25 to 35% of the length in the width direction of the protrusions.

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