JP2015024722A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which can suppress the generation of a crack while making local irregularities formed at a side wall part inconspicuous.SOLUTION: A decoration part 10 arranged at an external surface of a side wall part 3 comprises a large number of ridges 16 which are arranged at intervals in a tire circumferential direction C, and extend to a direction in which the ridges are inclined to a tire radial direction, and a pair of protruded bands 12, 14 in which a height H2 from the external surface of the side wall part 3 is higher than heights H1 of the ridges 16, and which extend along the tire circumferential direction C. A pair of the protruded bands 12, 14 are arranged so as to be overlapped with a part of the tire circumferential direction C with an interval in the tire radial direction, and the ridges 16 arranged in adjacent regions with the protruded bands 12, 14 sandwiched therebetween differ in directions inclined to the tire radial direction.

Description

  The present invention relates to a pneumatic tire provided with a decorative portion on the outer surface of a sidewall portion, and particularly relates to a pneumatic tire provided with a large number of ridges (projections) provided at intervals in the tire circumferential direction as the decorative portion. .

  In the tire sidewall, irregularities may occur in the portion corresponding to the joint portion at the beginning and end of winding of the carcass ply and the portion corresponding to the folded end portion of the carcass ply folded from the inside to the outside of the bead core. is there. Local unevenness generated in the sidewall portion does not affect the performance and durability of the tire, but causes the appearance quality to deteriorate.

  In order to make the local unevenness of the sidewall portion inconspicuous, the sidewall portion is provided with a large number of ridges that are inclined with respect to the tire radial direction and arranged in parallel with a minute interval. There are known pneumatic tires camouflaged with various irregularities (for example, Patent Documents 1 and 2 below).

  However, since a stress is generated in a direction inclined by approximately 45 ° with respect to the tire radial direction due to a twist generated between the tread and the bead when the tire rotates, if a ridge is arranged along this stress direction, There is a problem that a stress called a torque crack is likely to occur due to the concentration of stress in the recess.

  On the other hand, in the following cited document 1, by disposing a plurality of strip-shaped decorative portions having different ridge arrangement densities and inclination directions in the tire radial direction, the stress concentrated in the recesses between the ridges can be dispersed. However, since the border between the belt-like decorative portions adjacent to each other in the tire radial direction is in contact, there is a problem that stress cannot be sufficiently dispersed and cracks cannot be suppressed.

  Further, in Patent Document 2 below, since a non-patterned band is interposed between the belt-shaped decorative portions adjacent to each other in the tire radial direction, the stress concentrated in the recesses between the ridges can be dispersed to some extent. If you try to suppress the occurrence of cracks, the width of the patternless zone (the length in the tire radial direction) will increase, and as a result, the effect of camouflaging the local unevenness that occurs in the sidewall will be reduced. There is.

JP 2010-241397 A Japanese Patent Laid-Open No. 9-31511

  The present invention has been made in consideration of such problems, and an object of the present invention is to provide a pneumatic tire that suppresses the occurrence of cracks and has excellent durability while making local unevenness generated in a sidewall portion inconspicuous. And

  The pneumatic tire according to the present invention is a pneumatic tire provided with a decorative portion on an outer surface of a sidewall portion, wherein the decorative portion is provided at intervals in the tire circumferential direction and is inclined with respect to the tire radial direction. A plurality of ridges extending from the outer surface of the sidewall portion, and a pair of projecting strips that are higher than the ridges and extend along the tire circumferential direction, and the pair of projecting strips are in the tire radial direction. The ridges are arranged so that a part of the tire circumferential direction overlaps with a gap therebetween, and the ridges provided adjacent to each other across the protruding strip have different inclination angles with respect to the tire radial direction. .

  As a preferred aspect of the present invention, the pair of protruding strips may be provided in a spiral shape toward the outer side in the tire radial direction or the inner side in the tire radial direction as going to one end side in the tire circumferential direction. Moreover, a pair of said protruding strip may be provided so narrow that it goes to the edge part which overlaps with a tire peripheral direction. In the region provided between the pair of ridge bands, the ridge may be provided more densely in a portion where the pair of ridge bands overlap in the tire circumferential direction than in other portions. The ridge may have a repetition pitch of 5 mm or less, a height from the outer surface of the sidewall portion of 0.2 mm or more and 2.0 mm or less, and an inclination angle with respect to the tire radial direction of 20 ° to 70 °. The protruding strip may have a width of 1 mm or more and 10 mm or less, and a difference in height from the ridge of 1 mm or less, and the pair of protruding strips has a length overlapping with the tire circumferential direction of 200 mm or less. There may be.

  According to the present invention, it is provided with a pair of protruding strips that are arranged so as to overlap with each other in the tire circumferential direction with an interval in the tire radial direction and project higher than the ridge, and are provided in adjacent regions across the protruding strip. The resulting ridges have different inclination angles with respect to the tire radial direction, so that local unevenness that occurs in the sidewalls is less noticeable, and stress concentrated in the recesses between the ridges is dispersed to suppress the occurrence of cracks. be able to.

1 is a side view of a pneumatic tire according to an embodiment of the present invention. It is a principal part enlarged view of FIG. It is AA sectional drawing of FIG. (A) And (b) is sectional drawing equivalent to FIG. 3 in the pneumatic tire which concerns on the example of a change of this invention. (A) And (b) is a side view of the pneumatic tire which concerns on the Example of this invention. (A)-(c) is a side view of the pneumatic tire which concerns on a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a pneumatic tire (hereinafter referred to as “tire”) T according to an embodiment of the present invention, which includes a tread portion 2, sidewall portions 3 extending inward in the tire radial direction from both ends, and the sidewall portions. 3 and a bead portion 4 which is connected to the inner peripheral side and is fixed to the rim flange.

  On the outer surface of the sidewall portion 3 of the tire T, a plurality (two in the present embodiment) of decorative portions 10 protruding from the outer surface are provided in the tire circumferential direction C. The individual decorative portions 10 are different only in the positions provided on the sidewall portions 3 and the configuration of each decorative portion 10 is the same. Therefore, here, only one decorative portion 10 will be described, and the other decorative portion 10 will be described. The description of 10 is omitted.

  The decorative portion 10 includes a pair of projecting strips 12 and 14 extending along the tire circumferential direction C, and a large number of ridges (projections) 16 that are arranged at minute intervals in the tire circumferential direction C. Compared to 16, the pair of protruding strips 12, 14 has a higher protruding height from the outer surface of the sidewall portion 3.

  The pair of protruding strips 12 and 14 are arranged so that a part of the tire circumferential direction C overlaps with a gap in the tire radial direction.

  More specifically, the pair of ridge bands 12 and 14 includes a ridge band (hereinafter referred to as “inner ridge band”) 12 disposed inward in the tire radial direction, and an inner ridge band. A ridge band (hereinafter, this ridge band is referred to as an “outer ridge band”) 14 disposed radially outward from the band, and the end of the inner ridge band 12 and the outer ridge band 14 The end portion is a central portion of the decorative portion 10 in the tire circumferential direction C and overlaps the tire circumferential direction C with a gap in the tire radial direction.

  The inner ridge band 12 has one end portion 12a positioned at the center portion in the tire circumferential direction C of the decorative portion 10 positioned on the inner peripheral side of the decorative portion 10 and positioned at the end portion of the decorative portion 10 in the tire circumferential direction C. The other end portion 12b is located on the outer peripheral side of the decorative portion 10 with respect to the one end portion 12a. Thereby, the inner side strip 12 is provided in the spiral shape which goes to the tire radial direction outer side as it goes to the other end 12b from the one end 12a of the inner side strip 12 along the tire circumferential direction C. The other end portion 12 b of the inner protruding strip 12 is bent at an acute angle and extends to the outer peripheral edge of the decorative portion 10.

  The outer ridge band 14 is positioned at the end portion 14a of the decorative portion 10 in the tire circumferential direction C at the inner peripheral side of the decorative portion 10 and at the central portion of the decorative portion 10 in the tire circumferential direction C. The other end portion 14b is located outside the decorative portion 10 with respect to the one end portion 14a, and goes toward the outer side in the tire radial direction along the tire circumferential direction C from the one end portion 14a to the other end portion 14b. It is provided in a spiral. One end portion 14 a of the outer protruding strip 14 is bent at an acute angle and extends to the inner peripheral edge of the decorative portion 10.

  The inner ridge band 12 and the outer ridge band 14 are provided so as to be narrower toward the ends (one end 12a of the inner ridge band 12 and the other end 14b of the outer ridge band 14) overlapping in the tire circumferential direction C. It has been. That is, the inner ridge band 12 has a tapered shape in which the width (length along the tire radial direction) decreases from the other end 12b to the one end 12a, and the outer ridge band 14 has one end. It has a tapered shape with a width that decreases from 14a to the other end 14b.

  The inner ridge band 12 and the outer ridge band 14 divide the decorative portion 10 into three regions. Specifically, the first ridge band 12 is provided on the inner side in the tire radial direction of the inner ridge band 12. No. 1 provided in the region F1 and between the inner ridge band 12 and the outer ridge band 14 (that is, on the outer side in the tire radial direction of the inner ridge band 12 and on the inner side in the tire radial direction of the outer ridge band 14). It divides into 2 area | region F2 and 3rd area | region F3 provided in the tire radial direction outer side of the outer side protruding strip 14.

  A plurality of ridges 16 extending in a direction inclined with respect to the tire radial direction are provided in the first region F1, the second region F2, and the third region F3 defined by the inner ridge strip 12 and the outer ridge strip 14. It has been. The plurality of ridges 16 have a triangular shape as illustrated in FIG. 3, and the protruding height H <b> 1 from the outer surface of the sidewall portion 3 is the protrusion of the inner ridge band 12 and the outer ridge band 14. It is provided lower than the height H2.

  As shown in FIG. 2, the ridge 16 provided in the first region F1 is inclined clockwise by an angle θ1 with respect to the tire radial direction, and the ridge 16 provided in the second region F2 is aligned in the tire radial direction. In contrast, the ridge 16 is inclined counterclockwise by an angle θ2, and the ridge 16 provided in the third region F3 is inclined clockwise by an angle θ3 with respect to the tire radial direction. Accordingly, the ridges 16 provided in the first region F1 and the second region F2 adjacent to each other with the inner ridge band 12 interposed therebetween are different from each other in the direction inclined with respect to the tire radial direction. The ridges 16 provided in the second region F2 and the third region F3 that are adjacent to each other with the band 14 in between are also different from each other in the direction inclined with respect to the tire radial direction. The direction in which the ridge 16 inclines with respect to the tire radial direction is determined by the rotation direction and the rotation angle with respect to the tire radial direction passing through the inner end of the ridge 16 in the tire radial direction when viewed from the side of the tire.

  In the present embodiment, the second region F2 provided between the inner ridge band 12 and the outer ridge band 14 is a portion where the inner ridge band 12 and the outer ridge band 14 overlap in the tire circumferential direction C (decoration). Ridges 16 are densely provided in the portion 10 (portion located at the center in the tire circumferential direction C) compared to other portions (both ends in the tire circumferential direction C).

  Further, in the first region F1 provided on the inner side in the tire radial direction of the inner ridge strip 12 and the third region F3 provided on the outer side in the tire radial direction of the outer ridge strip 14, the tire circumferential direction C of the decorative portion 10 is illustrated. The ridges 16 are densely provided in the portion located at the end portion of the decorative portion 10 as compared with the portion located in the central portion of the decorative portion 10 in the tire circumferential direction C.

  Various dimensions of the inner ridge strip 12, the outer ridge strip 14, and the ridge 16 constituting the decorative portion 10 are not particularly limited, but an example of the various dimensions with reference to FIG. 2 and FIG. 16, the repetition pitch P is 5 mm or less, the protruding height H1 from the outer surface of the sidewall portion 3 is 0.2 mm or more and 2.0 mm or less, and the rotation angle with respect to the tire radial direction is 20 ° to 70 °. can do.

  When the repetitive pitch P of the ridge 16 is larger than 5 mm, the effect of camouflaging local irregularities generated in the sidewall portion 3 is reduced. If the protruding height H1 of the ridge 16 is smaller than 0.2 mm, the camouflage effect is reduced. If the protruding height H1 is larger than 2.0 mm, the rubber flows into the concave portion of the mold for molding the ridge 16 during vulcanization molding. Difficult to cause molding defects. If the rotational angle of the ridge 16 is out of the range of 20 ° to 70 °, the camouflage effect decreases.

  Further, the inner ridge band 12 and the outer ridge band 14 have a width W of 1 mm or more and 10 mm or less, a height difference δH from the ridge 16 of 1 mm or less, and a length L of a portion overlapping the tire circumferential direction C of 200 mm. It can be as follows.

  When the width W of the inner ridge strip 12 and the outer ridge strip 14 is smaller than 1 mm, the stress concentrated in the recesses between the adjacent ridges 16 is difficult to disperse. When the width W is larger than 10 mm, the ridge 16 occupying the sidewall portion 3 is provided. The area that cannot be enlarged becomes larger and the camouflage effect is reduced.

  When the height difference δH from the ridge 16 is 0 or less (that is, the height H2 of the inner ridge strip 12 and the outer ridge strip 14 is less than the height H1 of the ridge 16), the concave portion between the adjacent ridges 16 When the difference δH from the ridge 16 is greater than 1 mm, the rubber flow failure occurs.

  If there are no overlapping portions in the tire circumferential direction C of the inner ridge band 12 and the outer ridge band 14, the stress concentrated in the recesses between the adjacent ridges 16 becomes difficult to be dispersed, and the inner ridge band 12 and the outer ridge band 12 If the length L of the portion of the belt 14 overlapping in the tire circumferential direction C is larger than 200 mm, the region where the ridge 16 occupying the sidewall portion 3 is not provided and the camouflage effect is reduced.

  In the present embodiment, the inner ridge band 12 and the outer ridge band 14 are provided in a spiral shape toward the outer side in the tire radial direction from the one end 12a, 14a in the tire circumferential direction C to the other end 12b, 14b. Although the case has been described, the present invention is not limited to this, and it may be provided in an arc shape in which the position in the tire radial direction does not change as shown in FIG.

  In the present embodiment, in the second region F2 provided between the inner ridge band 12 and the outer ridge band 14, a portion where the inner ridge band 12 and the outer ridge band 14 overlap in the tire circumferential direction C. The ridges 16 are densely provided in comparison with other portions, but all the ridges 16 may be provided at equal intervals.

  In the present embodiment, the case where the cross-sectional shape of the ridge 16 is a triangle has been described. However, for example, a rectangular shape as shown in FIG. 4A or a semicircular shape as shown in FIG. Good.

  In the pneumatic tire of the embodiment as described above, the inner ridge band 12 and the outer ridge band 14 that are higher than the ridge 16 and extend along the tire circumferential direction C are higher than the height of the sidewall portion 3 from the outer surface. Since the tire circumferential direction C is arranged so as to overlap with a gap in the radial direction, the tire concentrates the stress concentrated on the recesses between the adjacent ridges 16 by the inner ridge band 12 and the outer ridge band 14. It can disperse | distribute in the circumferential direction C, and generation | occurrence | production of a crack can be suppressed.

  Further, since the ridges 16 provided in the adjacent regions across the inner ridge band 12 and the outer ridge band 14 are different from each other in the direction inclined with respect to the tire radial direction, the light reflection direction is dispersed. Since it becomes irregular, local unevenness generated in the sidewall portion 3 can be made inconspicuous.

  Moreover, the inner ridge band 12 and the outer ridge band 14 are provided in a spiral shape toward the outer side in the tire radial direction from the one end 12a, 14a in the tire circumferential direction C to the other end 12b, 14b. Since the light reflection direction by the ridge 16 provided in the first region F1, the second region, and the third region F3 defined by the ridge band 12 and the outer ridge band 14 becomes more irregular, the sidewall portion 3 can be made more inconspicuous.

  Furthermore, in the present embodiment, the inner and outer ridge bands 12 and 14 are provided narrower toward the end overlapping the tire circumferential direction C, and therefore concentrate in the recesses between adjacent ridges 16. Stress can be dispersed in the tire circumferential direction C, and a wide area for providing the ridge 16 can be secured in a portion where the inner ridge band 12 and the outer ridge band 14 overlap in the tire circumferential direction C, thereby preventing cracks. And improving the camouflage effect.

  Further, in the second region F2 provided between the inner ridge band 12 and the outer ridge band 14, a portion where the inner ridge band 12 and the outer ridge band 14 overlap in the tire circumferential direction C is another portion. Since the ridges 16 are densely provided, local unevenness generated in the sidewall portion 3 can be made more inconspicuous.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

  Tires (235 / 50R18) of Examples 1 to 3 and Comparative Examples 1 to 3 were made as trial products. Each of these prototype tires is manufactured by changing the specifications shown in Table 1 with the same basic tread pattern and tire internal structure. In Table 1, the width W is the width dimension of the inner ridge band 12 and the outer ridge band 14, and when the width dimension changes in the tire circumferential direction C, the minimum and maximum width dimensions are indicated. . Further, δH is the difference between the height H2 of the inner ridge strip 12 and the outer ridge strip 14 and the height H1 of the ridge 16 (= H2−H1), and the length L is the inner ridge strip 12 and the outer projection. The length of the portion where the strip 14 overlaps in the tire circumferential direction C, the pitch P is the repetitive pitch of the ridge 16, the height H1 is the height of the ridge 16 from the outer surface of the sidewall portion 3, and the inclination directions θ1 to θ3. Is a direction in which the ridges 16 provided in the first region F1, the second region F2, and the third region F3 are inclined with respect to the tire radial direction, with the counterclockwise direction being positive and the clockwise direction being negative. In addition, when the length L is minus, it represents the length in which the inner ridge strip 12 and the outer ridge strip 14 are separated in the tire circumferential direction C.

  Specifically, in Examples 1 to 3, the inner ridge band 12 and the outer ridge band 14 are arranged so that a part of the tire circumferential direction C overlaps with a gap in the tire radial direction. The side wall 3 is provided with decorative portions 10 in which the ridges 16 provided in the adjacent regions across the belt 12 and the outer ridge belt 14 are different from each other in the direction inclined with respect to the tire radial direction.

  Specifically, in Example 1, as shown in FIG. 5A, the inner ridge band 12 and the outer ridge band 14 are provided with a constant width in the circumferential direction, and the position in the tire radial direction is set. Is provided in an arc shape that does not change. In Example 2, as shown in FIG. 5B, the inner ridge band 12 and the outer ridge band 14 are provided with a constant width in the circumferential direction, and the one end portions 12 a and 14 a in the tire circumferential direction C are provided. To the other end 12b, 14b is provided in a spiral shape toward the outer side in the tire radial direction. In Example 3, as shown in FIG. 1, the inner ridge strip 12 and the outer ridge strip 14 are provided so narrow that they go to the end overlapping the tire circumferential direction C, and one end of the tire circumferential direction C is provided. As it goes from the portions 12a and 14a to the other end portions 12b and 14b, it is provided in a spiral shape toward the outer side in the tire radial direction.

  Moreover, as for the comparative examples 1-3, the decoration part 10 with which the direction in which the ridge 16 inclines with respect to a tire radial direction is constant is provided in the sidewall part 3 in all.

  Specifically, as shown in FIG. 6A, in Comparative Example 1, the inner protruding strip 12 and the outer protruding strip 14 do not exist, and the decorative portion 10 provided with only the ridge 16 is the sidewall portion 3. Is provided.

  In Comparative Example 2, as shown in FIG. 6B, the inner ridge band 12 and the outer ridge band 14 are provided in a spiral shape with a constant width in the tire circumferential direction C, and are spaced in the tire radial direction. It arrange | positions so that a part of tire circumferential direction C may overlap, opening.

  In Comparative Example 3, as shown in FIG. 6 (c), the inner ridge band 12 and the outer ridge band 14 are provided in a spiral shape with a constant width in the tire circumferential direction C, and in the tire circumferential direction C. The tires are arranged so as to be 16 mm apart and a portion in the tire circumferential direction C does not overlap.

(1) Torque cracks After traveling 30000 km at 70% of the actual vehicle specified air pressure, the presence or absence of cracks was confirmed on the sidewalls.

(2) Camouflage effect A sensory test was performed on the unevenness of the joint portion at the beginning and end of winding of the carcass ply of the sidewall portion 3 of the prototype tire from the front, and the result of Comparative Example 1 was evaluated as 100. The larger the value, the greater the camouflage effect.

  The results are as shown in Table 1. In Examples 1 to 3, the unevenness of the sidewall portion 3 can be made less noticeable than in Comparative Example 1, and the occurrence of sidewall cracks can be suppressed. .

T: Tire, 2 ... Tread part, 3 ... Side wall part, 4 ... Bead part, 10 ... Decoration part, 12 ... Inner ridge band, 14 ... Outer ridge band, 16 ... Ridge, F1 ... First region, F2 ... 2nd area, F3 ... 3rd area

Claims (7)

In a pneumatic tire having a decorative portion on the outer surface of the sidewall portion,
The decorative portion is provided with a plurality of ridges provided at intervals in the tire circumferential direction and extending in a direction inclined with respect to the tire radial direction, and the height from the outer surface of the sidewall portion is higher than the ridges in the tire circumferential direction. A pair of protruding strips extending along
The pair of protruding strips are arranged such that a part of the tire circumferential direction overlaps with a gap in the tire radial direction,
The pneumatic tire according to claim 1, wherein the ridges provided in the adjacent regions across the protruding strip are different from each other in a direction inclined with respect to a tire radial direction.   2. The pneumatic tire according to claim 1, wherein the pair of protruding strips are provided in a spiral shape toward the outer side in the tire radial direction toward the one end side in the tire circumferential direction.   3. The pneumatic tire according to claim 1, wherein the pair of protruding strips are provided narrower toward an end portion that overlaps in a tire circumferential direction.   The region provided between the pair of ridge bands is characterized in that the ridge is provided more densely in a portion where the pair of ridge bands overlap in the tire circumferential direction than in other portions. The pneumatic tire according to any one of claims 1 to 3.   The ridge has a repetitive pitch of 5 mm or less, a height from the outer surface of the sidewall portion of 0.2 mm to 2.0 mm, and an angle with respect to a tire radial direction of 20 ° to 70 °. Item 5. The pneumatic tire according to any one of Items 1 to 4.   6. The pneumatic tire according to claim 1, wherein the pair of protruding strips has a width of 1 mm or more and 10 mm or less and a height difference from the ridge of 1 mm or less. .   The pneumatic tire according to any one of claims 1 to 6, wherein the pair of protruding strips has a length of 200 mm or less overlapping in a tire circumferential direction.

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