JP5886914B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that can enhance the blinding effect of a dent caused by a splice portion of a carcass ply appearing in a sidewall portion and prevent appearance deterioration.

  The pneumatic tire is reinforced with a carcass ply formed of a carcass cord layer. The carcass ply is formed in a ring shape in which a sheet is wound around the tire in the circumferential direction, and both ends thereof are spliced (spliced) with a small width. However, since the carcass ply locally overlaps in two layers, the splice portion has higher rigidity than other portions. Therefore, when the pneumatic tire is filled with air, the splice portion of the carcass ply does not easily extend, and appears as a dent portion, particularly in the thin sidewall portion of the covering rubber. Such a recess has a problem of deteriorating the appearance, for example, interrupting the uniformity of the sidewall in the tire circumferential direction.

  Conventionally, in order to solve such problems, various proposals have been made to form an annular decorative pattern called serration in which a plurality of ridges are arranged in the tire circumferential direction at a predetermined pitch on the sidewall portion. . Patent Document 1 below describes changing the ridge pitch. Such a decorative pattern can be expected to have a so-called blinding effect that makes the dent produced by the splice part inconspicuous.

Japanese Patent Laid-Open No. 7-164831

  However, as in the conventional method, a sufficient blinding effect of the dent is not obtained only by changing the ridge pitch.

  The present invention has been devised in view of the above-described problems. The cross-sectional shape of each ridge includes an outer surface portion positioned on the tire outer side and a pair of inclined side surfaces extending from both ends of the outer surface portion to the tire inner side. Basically, two or more types of ridges having different lengths of the outer surface and / or adjacent ridges and different lengths of bottom surfaces located inside the tire are included. Thus, an object of the present invention is to provide a pneumatic tire that can further effectively enhance the blinding effect of the recessed portion caused by the splice portion or the like.

  The invention according to claim 1 of the present invention is a pneumatic tire in which an annular decorative pattern is formed on a sidewall portion by arranging a plurality of ridges in the tire circumferential direction at a pitch of 0.5 to 5.0 mm. A carcass ply formed by splicing a carcass ply, wherein the decorative pattern is composed of two or more types of ridges having different cross-sectional shapes, and the decorative pattern includes two ridges having the same cross-sectional shape The ridge group is formed by arranging the ridge groups continuously arranged in the tire circumferential direction with the ridge group continuously arranged in the above and 17 or less in the tire circumferential direction, the length in the tire circumferential direction of the splice portion of the carcass ply, and the ridge group The at least one tire circumferential length is substantially equal.

  The invention according to claim 2 is that the cross-sectional shape of each of the ridges is an approximate base having an outer surface portion located on the outer side of the tire and a pair of inclined side surface portions extending from both ends of the outer surface portion to the inner side of the tire. 2. The pneumatic tire according to claim 1, wherein two or more types of ridges having different shapes and different cross-sectional shapes are different in length of the outer surface portion.

  According to a third aspect of the present invention, the ridge group includes a first ridge group in which first ridges are arranged, and a second ridge group in which second ridges having a different cross-sectional shape from the first ridge are arranged. 3. The pneumatic tire according to claim 2, wherein the first ridge and the second ridge are different from each other in sum of a length of the outer surface portion and a length of the bottom surface portion.

  The invention according to claim 4 is the pneumatic tire according to claim 2 or 3, wherein each of the ridges has a cross-sectional asymmetric shape due to a difference in inclination angle between the pair of inclined side surface portions on the left and right.

  According to a fifth aspect of the present invention, the ridge group includes a first ridge group in which first ridges are arranged, and a second ridge group in which second ridges having a different cross-sectional shape from the first ridge are arranged. 5. The pneumatic tire according to claim 2, wherein the first ridge and the second ridge have different angles of inclined side surface portions provided on the same side in the tire circumferential direction.

  The invention according to claim 6 of the present invention is a pneumatic tire in which an annular decorative pattern is formed on the sidewall portion by arranging a plurality of ridges in the tire circumferential direction at a pitch of 0.5 to 5.0 mm. A carcass ply formed by splicing a carcass ply, wherein the decorative pattern is composed of two or more types of ridges having different cross-sectional shapes, and the decorative pattern includes two ridges having the same cross-sectional shape The ridge group is formed by arranging the ridge groups continuously arranged in the tire circumferential direction with the ridge group continuously arranged in the above and 17 pieces or less in the pattern unit, and the ridge group includes the first ridge group in which the first ridges are arranged. The first ridge includes a second ridge group in which second ridges having different cross-sectional shapes are arranged, and the length of the splice portion of the carcass ply in the tire circumferential direction is the first ridge. Tsu larger than the tire circumferential direction length of the di-group, and is characterized in that is smaller than the length in the tire circumferential direction of the second ridge group.

  The pneumatic tire of the present invention includes a carcass formed by splicing a carcass ply, and a plurality of ridges are arranged in the tire circumferential direction at a pitch of 0.5 to 5.0 mm on the sidewall portion. An annular decorative pattern is formed. This decorative pattern is composed of two or more types of ridges having different cross-sectional shapes. Two or more types of ridges having different cross-sectional shapes constitute a group of ridges that are successively arranged with two or more and 17 or less. The decorative pattern is formed by arranging ridge groups of different types in the tire circumferential direction with the ridge group as a pattern unit. In this way, by arranging a plurality of types of ridge groups composed of ridges having different cross-sectional shapes in the tire circumferential direction, the blinding effect such as blurring of the recessed portion having a certain width is further improved.

  In the present invention, the length in the tire circumferential direction of the splice portion of the carcass ply is substantially equal to the length in the tire circumferential direction of the ridge group. For this reason, not only when the splice portion overlaps with the ridge group, but also when the two are misaligned, the pattern change between the ridge groups makes the dent portion less noticeable and improves the appearance of the sidewall portion. .

It is a side view of the pneumatic tire of this embodiment. It is the elements on larger scale of the decoration pattern. (A) is AA sectional drawing of FIG. 2, (b) is BB sectional drawing of FIG. It is sectional drawing of the ridge which shows other embodiment of this invention. It is sectional drawing of the ridge which shows other embodiment of this invention. (A)-(c) is sectional drawing of the ridge of an Example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a side view of the pneumatic tire of the present embodiment. The pneumatic tire 1 includes a tread portion 2 that contacts the road surface, a pair of sidewall portions 3 that extend inward in the tire radial direction from both sides of the tread portion 2, and a bead continuous to the inner end of the sidewall portion 3. Part 4.

  The pneumatic tire 1 of this embodiment is for a passenger car. For example, a radial carcass 5 is arranged inside the pneumatic tire 1. The carcass 5 has a sheet-like carcass ply 5a extending in the tire circumferential direction, and a splice portion 6 is formed by overlapping both ends thereof.

  An annular decorative pattern 8 is formed on the sidewall portion 3. FIG. 2 shows the decorative pattern 8 in an enlarged manner. As shown in FIGS. 1 and 2, the decorative pattern 8 extends continuously in the tire circumferential direction in this embodiment. If necessary, the decorative pattern 8 may be interrupted in the tire circumferential direction, or characters 9 or the like representing a tire logo mark or brand name may be formed on the decorative pattern 8 in a relief shape. The length H of the decorative pattern 8 in the tire radial direction is not particularly limited, but is preferably about 5 to 30% of the tire cross-section height.

  The decorative pattern 8 is formed by arranging a plurality of ridges 7 at a predetermined pitch in the tire circumferential direction. As shown in FIGS. 3A and 3B, the ridge 7 is a thin hook-shaped protrusion that protrudes from the outer surface of the sidewall portion 3 and extends linearly.

  In the present embodiment, the decorative pattern 8 includes two types of ridges having different cross-sectional shapes, that is, a first ridge 7A shown in FIG. It is comprised from the 2nd ridge 7B shown by FIG.3 (b) which is B cross section. When these ridges 7A and 7B are collectively referred to without distinction, they may be expressed as “ridge 7”.

  Further, as shown in FIGS. 3A and 3B, the ridges 7 need to be arranged in the tire circumferential direction at a pitch P of 0.5 to 5.0 mm. The purpose of forming the ridge 7 is to exert a blinding effect that makes the concave portion caused by the splice portion 6 and the like of the carcass ply 5a inconspicuous. However, if the pitch P of the ridge 7 is too large, the blinding effect is not sufficiently exhibited and the above-mentioned purpose cannot be achieved, so the upper limit of the pitch P is set to 5.0 mm or less. On the other hand, since the ridge 7 is formed by a tire vulcanization mold, the lower limit of the pitch P is set to 0.5 mm or more in consideration of mold workability and productivity. Although not particularly limited, the pitch P is preferably about 1.0 to 3.0 mm.

  Each of the cross-sectional shapes of the first ridge 7A and the second ridge 7B has an outer surface portion 13 located on the outer side of the tire and a pair of inclined side surface portions 14 extending from both ends of the outer surface portion 13 to the inner side of the tire. Consists of a substantially trapezoidal shape. Further, a bottom surface portion 15 located inside the tire is formed between adjacent ridges 7 and 7. The reason why the cross-sectional shape of the ridge 7 is a “substantially” trapezoidal shape is that it is difficult to form a strict trapezoidal shape in consideration of the size of the ridge 7 and rubber molding technology, and a trapezoidal corner. This is because the portion or the like is allowed to include a small chamfer.

  When facing the side surface of the pneumatic tire 1 (that is, the sidewall portion 3), the substantially trapezoidal ridge 7 reflects more light at the outer surface portion 13 and the bottom surface portion 15, so these portions appear whitish. . On the other hand, since the reflectance of the inclined side surface portion 14 is relatively lower than that of the outer surface portion 13 and the bottom surface portion 15, the original black color of the tire appears strongly and looks black. Therefore, the ridge 7 forms such a change in lightness in the tire circumferential direction, thereby blurring the lightness change formed by the recess and making it inconspicuous.

  Further, as shown in FIG. 2, the decorative pattern 8 of the present embodiment is different in type, with the ridge group having the same cross-sectional shape continuously arranged in the number of 2 or more and 17 or less as a pattern unit. It is formed by arranging ridge groups (pattern units) in the tire circumferential direction. In this embodiment, a first ridge group 10 in which the first ridges 7A are continuously arranged within the range of the number, and a second ridge group in which the second ridges 7B are arranged in the range of the number. 11 and these are alternately provided.

  The ridge groups 10 and 11 forming the pattern unit of the decorative pattern 8 are formed in order to obtain a blinding effect that blurs the concavity caused by the splice portion 6 of the carcass ply 5a and makes it inconspicuous. Therefore, approximating the length CL in the tire circumferential direction of the ridge groups 10 and 11 to the length PL in the tire circumferential direction of the splice portion 6 is particularly effective in enhancing the blinding effect. In general, the length PL in the tire circumferential direction of the splice portion 6 is about 4 to 25 mm on the inner edge 8e of the decorative pattern 8.

  The inventors have conducted various experiments on radial tires for passenger cars. As a result, even if one ridge 7 is arranged, that is, two ridges 7 are alternately arranged in the tire circumferential direction, the blinding effect is not sufficient. I understood. Further, even if the number of ridges 7 included in the ridge group is increased, a deviation from the length PL in the tire circumferential direction of the splice portion 6 occurs, and a blinding effect cannot be sufficiently obtained. For this reason, the ridge group needs to be formed by arranging 2 to 17 identical ridges 7, particularly preferably 3 or more, more preferably 4 or more, and preferably 15 or less. More preferably, 13 or less is desirable.

  Furthermore, in order to enhance the blinding effect, it is important that the two types of ridges 7A and 7B having different cross-sectional shapes have different lengths of the outer surface portion 13 and / or the bottom surface portion 15. In the present embodiment, the length Loa of the outer surface portion 13 of the first ridge 7A is different from the length Lob of the outer surface portion 13 of the second ridge 7B, and is configured as Loa <Lob. Similarly, the length Lia of the bottom surface portion 15 of the first ridge 7A is different from the length Lib of the bottom surface portion 15 of the second ridge 7B, and is configured as Lia <Lib. In particular, when the first ridge 7A and the second ridge 7B are not distinguished from each other, the length of the outer surface portion thereof is simply expressed as “Lo” and the length of the bottom surface portion is expressed as “Li”. The

  In the decorative pattern 8 configured as described above, the length CL in the tire circumferential direction of each of the ridge groups 10 and 11 is equal to the length PL in the tire circumferential direction of the splice portion 6 of the carcass ply 5a (and hence due to this). This approximates or coincides with the tire circumferential length of the resulting dent. For this reason, not only when the splice part 6 overlaps with the ridge group, but also when the two parts are misaligned, the switching of the pattern between the ridge groups 10 and 11 makes the recess part less noticeable and the sidewall part 3. Improve the appearance. Accordingly, the tire circumferential direction length CL of the splice portion 6 of the carcass ply 5a on the inner edge 8e in the tire radial direction of the decorative pattern 8 and the tire circumferential direction at the inner edge 8e of at least one of the ridge groups 10 and 11 are arranged. It is desirable that the length CL is substantially equal. Here, “substantial” is considered in consideration of the difficulty of making the lengths CL and PL completely coincide with each other in consideration of the molding accuracy of the tire. At least the difference in length is 10 mm. Shall be included. In particular, by making the length PL of the splice portion larger than the length CL1 of the first ridge group 10 and smaller than the length CL2 of the second ridge group 11, the recess portion can be more effectively formed. Blur effect is demonstrated.

  Further, since the ridges 7 of the ridge groups 10 and 11 are different in the length Lo of the outer surface portion 13 and / or the length Li of the bottom surface portion 15, the blinding effect can be further enhanced. As a preferred embodiment, the first ridge 7A and the second ridge 7B are desirably different from each other in the sum Lo + Li of the length Lo of the outer surface portion 13 and the length Li of the bottom surface portion 15. When facing the sidewall 3, the outer surface portion 13 and the bottom surface portion 15 reflect white light more and appear white, so that the sum Lo + Li of these widths is changed between the ridge groups 10, 11 so as to be blinded. The effect is exhibited more effectively.

  For example, even when both the length Lo of the outer surface portion 13 and the length Li of the bottom surface portion 15 are different, if the sum Lo + Li does not change between the ridge groups, there is a sufficient brightness difference between the ridge groups. There is a tendency not to be obtained. When only the length Lo of the outer surface portion or only the length Li of the bottom surface portion is changed, the sum Lo + Li also changes, but both the length Lo of the outer surface portion 13 and the length Li of the bottom surface portion 15 are both changed. By making the sum Lo + Li different, the difference in brightness is further increased, and the blinding effect is further improved.

  As shown in FIG. 3, the length Lo of the outer surface portion 13 and the length Li of the bottom surface portion 15 of the ridge 7 are not particularly limited, but are preferably 0.1 mm or more, more preferably 0.2 mm or more, Further, it is preferably 3.5 mm or less, more preferably 2.0 mm or less. Further, the angle θ of the end spread of the inclined side surface portion 14 is preferably larger than 0 °, but is preferably set within a range of 85 ° or less, more preferably 75 ° or less. Further, the height h of the ridge 7 is preferably 0.3 mm or more, more preferably 0.5 mm or more, and preferably 1.0 mm or less.

  Furthermore, as a preferable aspect, as shown in FIG. 4, the ridges 7 preferably have a left-right asymmetrical cross section because the inclination angles θL and θR of the pair of left and right inclined side surface portions 14 are different. Such a ridge 7 is liable to cause a difference in brightness at the left and right inclined side surface portions 14, thereby causing a more complicated change in brightness and further improving the blinding effect. In particular, the angle difference | θL−θR | between the left and right inclined side surface portions 14 is preferably 2 ° or more, more preferably 3 ° or more, and preferably 10 ° or less.

  As shown in FIG. 5, in the first ridge 7A and the second ridge 7B, the angle of the end spread of the inclined side surface portion 14 provided on the same side (right side in this figure) in the tire circumferential direction is θ1. , Θ2 (> θ1). For example, when the inclined side surface portion 14 is viewed from the normal direction from one side S1 in the tire circumferential direction, the inclined side surface portion 14 also appears bright due to reflection. At this time, since the inclined side surface portion 14 on the other side S2 of the ridge 7 is not originally visible, the brightness is not affected. Therefore, the brightness can be varied more effectively by making the inclination angle of the inclined side surface portion 14 located on the same side in the tire circumferential direction different between the first ridge 7A and the second ridge 7B. .

  As described above, even when the sidewall portion 3 of the pneumatic tire 1 is viewed obliquely, the angle of the inclined side surface portion 14 changes in the first ridge group 10 and the second ridge group 11 so that it looks bright. Since the direction changes between ridges, the change in brightness is complicated, which helps to further enhance the blinding effect. The angle difference | θ1−θ2 | is preferably 2 ° or more, more preferably 3 ° or more, and preferably 10 ° or less.

  In FIG. 5, the inclined side surface portion on the other side in the tire circumferential direction is displayed at the same angle, but the first ridge 7 </ b> A and the second ridge 7 </ b> B are also displayed on the inclined side surface portion on this side. Can be different.

  As mentioned above, although embodiment of this invention was explained in full detail, it cannot be overemphasized that this invention can be deform | transformed and implemented in various aspects, without being limited to the said embodiment. For example, even if three or more types of ridges having different cross-sectional shapes are used, the same effect as the above embodiment is expected. Even if the number of types of ridges 7 is increased, productivity may be deteriorated.

  In order to confirm the effect of the present invention, a plurality of types of pneumatic tires of size 175 / 60R14 were prototyped based on the specifications in Table 1, and an appearance evaluation test of the sidewall portion was performed. This pneumatic tire had one carcass ply, and the length PL at the inner edge of the decorative pattern at the splice portion of the carcass ply was 12 mm. The decorative pattern was provided alternately with two first ridge groups and two second ridge groups. As a result, a region where the decorative pattern is formed and a region where the decorative pattern is not formed are intentionally provided in the sidewall portion. Details of the ridges in the ridge group are shown in FIG. 6, and three types of ridges were used in this embodiment.

  In addition, the appearance evaluation test compares the area where the decorative pattern on the side wall is formed with the area where the decorative pattern is not formed, and how much the concavity due to the splice part of the carcass ply is conspicuous on the decorative pattern. Whether it was blurred or not was observed with the naked eyes of five testers. The result is a relative evaluation with 100 being not known at all due to the tester's sensory and 60 points being Comparative Examples 1 and 2, and the average value of the five testers is shown. A larger numerical value indicates that the dent is not conspicuous and the appearance is better.

  As a result of the test, it was confirmed that the tires of the examples exhibited significant performance as compared with the comparative examples.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Carcass 5a Carcass ply 7 Ridge 7A 1st ridge 7B 2nd ridge 8 Decoration pattern 10 1st ridge group 11 2nd ridge group

Claims (6)

A pneumatic tire in which an annular decorative pattern is formed by arranging a plurality of ridges on the sidewall portion in the tire circumferential direction at a pitch of 0.5 to 5.0 mm,
Comprising a carcass formed by splicing a carcass ply;
The decorative pattern is composed of two or more types of ridges having different cross-sectional shapes,
In addition, the decorative pattern is formed by arranging ridge groups having two or more and 17 or less ridges having the same cross-sectional shape continuously arranged in a pattern unit, and arranging different types of ridge groups in the tire circumferential direction,
A pneumatic tire characterized in that a length in the tire circumferential direction of the splice portion of the carcass ply is substantially equal to a length in the tire circumferential direction of the ridge group. Each of the cross-sectional shapes of the ridges has a substantially trapezoidal shape having an outer surface portion located on the tire outer side and a pair of inclined side surface portions extending from both ends of the outer surface portion to the tire inner side,
The pneumatic tire according to claim 1, wherein the two or more types of ridges having different cross-sectional shapes have different lengths of the outer surface portion. The ridge group includes a first ridge group in which first ridges are arranged, and a second ridge group in which second ridges having a different cross-sectional shape from the first ridge are arranged,
The pneumatic tire according to claim 2, wherein the first ridge and the second ridge have different sums of the length of the outer surface portion and the length of the bottom surface portion.   4. The pneumatic tire according to claim 2, wherein each of the ridges has a cross-sectional asymmetric shape due to a difference in inclination angle between the pair of inclined side surfaces on the left and right. The ridge group includes a first ridge group in which first ridges are arranged, and a second ridge group in which second ridges having a different cross-sectional shape from the first ridge are arranged,
The pneumatic tire according to any one of claims 2 to 4, wherein the first ridge and the second ridge have different angles of inclined side surface portions provided on the same side in the tire circumferential direction. A pneumatic tire in which an annular decorative pattern is formed by arranging a plurality of ridges on the sidewall portion in the tire circumferential direction at a pitch of 0.5 to 5.0 mm,
Comprising a carcass formed by splicing a carcass ply;
The decorative pattern is composed of two or more types of ridges having different cross-sectional shapes,
In addition, the decorative pattern is formed by arranging ridge groups having two or more and 17 or less ridges having the same cross-sectional shape continuously arranged in a pattern unit, and arranging different types of ridge groups in the tire circumferential direction,
The ridge group includes a first ridge group in which first ridges are arranged, and a second ridge group in which second ridges having a different cross-sectional shape from the first ridge are arranged,
The length in the tire circumferential direction of the splice portion of the carcass ply is greater than the length in the tire circumferential direction of the first ridge group and smaller than the length in the tire circumferential direction of the second ridge group. Pneumatic tire characterized by.

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