JP2005104385A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve icing performance such as braking performance and driving performance from the initial stage of abrasion. <P>SOLUTION: In this pneumatic tire, grooves are cut in a tread 1 to partition and blocks and/or ribs. Two or more narrow grooves 3 extending from the grounding end 2 of the tread in the direction A of the rotating axis of the tire are cut in a buttress part 10. The width w1 of the narrow groove 3 is set 0.5 mm to 2.0 mm, and the interval w2 of the narrow groove 3 is set 0.5 mm to 2.0 mm. Further, the depth d of the fine groove 3 is set to 0.5 mm to 2.0 mm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly to an improvement in performance on an ice road surface.

  Conventionally, in a stud tire, a large number of sipes are cut on the tread surface to improve ice performance. Further, the tread shoulder portion is not rounded (round shoulder), but as shown in FIG. 1, the tread 1 and buttress portion 10 have a grounded end 2 with a square shape (square shoulder). The effect has been improved and ice performance has been improved.

In order to enhance the edge effect in the front-rear direction, there is a tire provided with a protrusion whose height gradually increases in the groove bottom direction on the side wall of the main groove continuous in the tire circumferential direction. For example, a pneumatic tire described in Patent Document 1 is known.
Published patent publication 2000-280713

  In such a conventional pneumatic tire, the lateral edge effect of the square shoulder works against a lateral load such as a skid. However, there is a problem that the edge effect due to the square shoulder cannot be expected when a longitudinal load is applied during braking or driving. In the tire provided with the above-described prior art protrusion, the height of the protrusion is not sufficient in the initial stage of wear. Therefore, a sufficient edge effect in the front-rear direction cannot be obtained, and the braking performance and the like have not been improved.

  Accordingly, an object of the present invention is to improve ice performance such as braking performance and driving performance from the initial stage of wear.

  As a result of intensive studies to solve the above-mentioned problems, the invention according to claim 1 is directed to a pneumatic tire in which a groove is engraved in a tread and blocks and / or ribs are defined. A pneumatic tire having a plurality of narrow grooves extending in the axial direction carved in the buttress portion was used.

  Since the plurality of narrow grooves are carved, a protrusion extending toward the tire rotation axis sandwiched between the narrow grooves is formed. When the side wall of the protrusion (the side wall of the narrow groove) is in contact with the ground, an edge effect in the front-rear direction can be exhibited. As a result, braking performance and driving performance are improved. Further, the shape of the shoulder portion is not limited, but if the shape is a square shape, the lateral edge effect due to the portion not engraved with the narrow groove is maintained.

  In addition, it is preferable that the narrow groove is carved to the use limit (50% of groove depth) of a studless at least. Further, the narrow groove may extend straight toward the tire rotation axis, or may extend obliquely.

  The invention according to claim 2 is the pneumatic according to claim 1, wherein the width of the narrow groove is 0.5 mm to 2.0 mm, and the distance between the narrow grooves is 0.5 mm to 2.0 mm. Tire.

  If the width of the narrow groove is less than 0.5 mm, the interval between the side walls of adjacent narrow grooves becomes narrow, and the side walls are not sufficiently grounded, so that the edge effect cannot be sufficiently obtained. If the interval between the narrow grooves, that is, the width of the protrusion formed by the narrow groove is less than 0.5 mm, the rigidity of the protrusion is lowered, the protrusion is liable to move low, the grounding property is deteriorated, and the ice performance is lowered. Further, if the width of the narrow groove or the interval between the narrow grooves exceeds 2.0 mm, the number of protrusions formed per unit length is reduced, so that the edge effect cannot be sufficiently obtained.

  The invention according to claim 3 is the pneumatic tire according to claim 1 or 2, wherein the depth of the narrow groove is 0.5 mm to 2.0 mm.

  If the depth of the narrow groove is less than 0.5 mm, the side wall to be grounded is short, so that the edge effect cannot be sufficiently obtained. On the other hand, when the depth of the narrow groove exceeds 2.0 mm, the rigidity becomes low and it is easy to move, the grounding property is deteriorated, and the ice performance is lowered.

  Invention of Claim 4 was set as the pneumatic tire in any one of Claim 1 thru | or 3 provided with the connection part which connects the said narrow grooves in a tire circumferential direction.

  Since the narrow grooves, that is, the protrusions are connected in the tire circumferential direction by the connecting portion, the rigidity of the protrusions in the tire circumferential direction is increased. As a result, ice performance does not deteriorate. In addition, the narrow groove can be protected from contact with a curb or the like. In addition, it is preferable that the connection part protrudes from the same height or protrusion as the protrusion.

  The pneumatic tire according to the present invention has a structure in which a plurality of fine grooves extending in the tire width direction from the ground contact end and extending toward the tire rotation axis are formed in the buttress portion. Therefore, the edge effect is exhibited in any of the front and rear directions by the side walls of the narrow grooves. As a result, braking performance and driving performance are improved.

  Hereinafter, embodiments of a pneumatic tire according to the present invention will be described with reference to the drawings. FIG. 2 is a perspective view showing a shoulder portion of a tread of a pneumatic tire according to the present invention, and shows a shoulder portion of a block having an angular square shape. A plurality of fine grooves 3 extending in the tire rotation axis direction A are engraved on the buttress portion 10 from the ground contact end 2, and a protrusion 4 sandwiched between the fine grooves 3 is formed.

  The narrow groove 3 is carved so that the tire width direction B is the depth direction. Therefore, the driving performance on the ice road surface is improved by the edge effect of the depression side wall 4a of the protrusion 4 with respect to the tire circumferential direction R shown in the figure. Further, the braking performance on the ice road surface is improved by the edge effect of the protrusion side wall 4b of the protrusion 4. Further, the remaining square shoulder 2a causes a lateral edge effect, and as a result, the turning performance on the ice road surface is maintained.

  The width w1 of the fine groove 3 is preferably 0.5 mm to 2.0 mm, and the interval w2 of the fine groove 3 is preferably 0.5 mm to 2.0 mm. When the width w1 of the narrow groove is less than 0.5 mm, the interval between the side walls 4a and 4b of the adjacent narrow grooves 3 is narrowed and the side walls 4a and 4b are not sufficiently grounded, so that the edge effect can be sufficiently obtained. Can not. If the interval between the narrow grooves 3, that is, the width w2 of the protrusions 4 formed by the narrow grooves 3, is less than 0.5 mm, the rigidity of the protrusions 4 is lowered, the protrusions 4 are easy to move, and the grounding property is deteriorated. Performance decreases. If the width w1 of the narrow grooves 3 and the interval w2 between the narrow grooves exceed 2.0 mm, the number of protrusions 4 formed per unit length is reduced, so that the edge effect cannot be sufficiently obtained.

  The depth d of the narrow groove 3 is preferably 0.5 mm to 2.0 mm. When the depth d of the narrow groove 3 is less than 0.5 mm, the side walls 4a and 4b to be grounded are short, so that the edge effect cannot be sufficiently obtained. On the other hand, when the depth d of the narrow groove exceeds 2.0 mm, the rigidity becomes low and it is easy to move, the ground contact property is deteriorated, and the ice performance is lowered.

  In addition, as shown in FIG. 3, the width w1 of the narrow groove 3 becomes narrower toward the groove bottom, and the protrusion 4 can have a substantially trapezoidal cross section. With such a shape, since the rigidity in the front-rear direction of the protrusion 4 is increased, the edge effect is enhanced.

  FIG. 4 shows an example provided with a connecting portion 6 that connects the narrow grooves 3 to each other. Since the narrow grooves 3, that is, the protrusions 4 are connected to each other in the tire circumferential direction R by the connecting portion 6, the rigidity of the protrusion 4 in the tire circumferential direction R is increased. As a result, the ice performance does not deteriorate without impairing the edge effect in the front-rear direction. Further, the narrow groove 3 and the protrusion 4 can be protected from contact with a curbstone or the like.

  In addition to the zigzag shape shown in the figure, the connecting portion 6 may have a strip shape extending in the tire circumferential direction R, or may connect only a part of the narrow groove 3. In addition, it is preferable that the connection part 6 protrudes from the same height as the protrusion 4 or the protrusion 4 as illustrated.

  Although the shoulder portion of the block pattern has been described above, it is possible to cut a narrow groove only in the shoulder portion of a part of the blocks, and even in the case of a round shoulder, the narrow groove can be cut and the ice performance can be improved. Moreover, even if it is a rib pattern or a rib lug pattern, a narrow groove is carved in a shoulder part and ice performance can be improved similarly.

  The pneumatic tire according to the present invention was prototyped as an example and a comparative example, and the pneumatic tire without a narrow groove was prototyped as a conventional example, and the performance was evaluated by mounting the tire on a domestic 2000cc front-wheel drive passenger car. As shown in FIG. 5, the pattern of the example and the comparative example includes a block 13 partitioned into a main groove 11 and a lateral groove 12, and a sipe 14 is engraved in the block 13. The pattern of the conventional example is the same pattern as the example except that the narrow groove is not carved. The tire size is 205 / 65R15, and the dimensions of the narrow groove are as shown in Table 1.

  Ice braking is the reciprocal of the braking distance from 40km / h to full lock on the ice road surface, ice driving is the reciprocal of the arrival time from the stop state to 30m on the ice road surface, and the ice turning is the Remni skate curve (character figure 8) It is the reciprocal of lap lime on the ice road. Each is an evaluation at the time of a new article, and is expressed as an index with the conventional example being set to 100. A larger index indicates better performance. According to the results shown in Table 1, in the pneumatic tire according to the present invention, the ice braking performance and the ice driving performance are improved, and the ice turning performance is maintained.

It is a perspective view which shows the shoulder part of the tread of the conventional pneumatic tire. It is a perspective view which shows the shoulder part of the tread of the pneumatic tire which concerns on this invention. It is a perspective view which shows other embodiment of the shoulder part of the tread of the pneumatic tire which concerns on this invention. It is a perspective view which shows other embodiment of the shoulder part of the tread of the pneumatic tire which concerns on this invention. It is a figure which shows the pattern expanded view of the Example of the pneumatic tire which concerns on this invention.

Explanation of symbols

1 Tread 2 Grounding End 3 Narrow Groove 4 Projection 6 Connecting Portion

Claims (4)

In pneumatic tires where grooves are carved in the tread and blocks and / or ribs are defined,
A pneumatic tire in which a plurality of fine grooves extending in a tire rotation axis direction from a ground contact end of the tread are carved in a buttress portion. 2. The pneumatic tire according to claim 1, wherein a width of the narrow groove is 0.5 mm to 2.0 mm, and a distance between the narrow grooves is 0.5 mm to 2.0 mm. The pneumatic tire according to claim 1 or 2, wherein a depth of the narrow groove is 0.5 mm to 2.0 mm. The pneumatic tire according to claim 1, further comprising a connecting portion that connects the narrow grooves in the tire circumferential direction.

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