JP2009143488A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent poor tire appearance by providing a fine groove on a ridge. <P>SOLUTION: This invention relates to a pneumatic tire 1 having serration pattern 4 extending in substantially belt shape in a tire circumference direction by providing the ridge 3 extending in a tire radial direction on an outer surface 2a of a side wall part 2 with keeping interval in the tire circumference direction. The ridge 3 includes a ridge 3A with a groove provided with at least one fine groove 7 extending along a longitudinal direction of the ridge 3 on a surface thereof. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire having a belt-like serration pattern formed by densely separating a large number of ridges extending in the tire radial direction on the surface of a sidewall portion in the tire circumferential direction.

  A molding defect such as local bulge (bulge) and / or dent (dent) may occur on the surface of the sidewall portion of the pneumatic tire vulcanized by a mold. Further, in a pneumatic tire having a carcass ply wound around the bead core from the inner side to the outer side in the tire axial direction, the folded end of the carcass ply may appear in a step shape on the surface of the sidewall part. .

  In order to make the unevenness of the surface of the sidewall portion as inconspicuous as possible, serrations are formed by closely separating ridges, which are small protrusions extending in the tire radial direction, on the surface of the sidewall portion in the tire circumferential direction. It has been proposed to form a pattern (see Patent Document 1 below). Such a serration pattern enhances the appearance of the tire without conspicuous appearance defects such as local bulges. In addition, various logo marks and marks are three-dimensionally displayed on the sidewall portion, and the serration pattern is useful for enhancing the visibility of these side designs.

JP 2004-17829 A

  However, the ridge employed in the conventional serration pattern, for example, has a simple cross section, such as a triangle shape or a bullet shape, with a cross section perpendicular to the longitudinal direction thereof, thus improving the concealment of the above-mentioned molding defects. There was room for further improvement.

  The present invention has been devised in view of the actual situation as described above, and includes a ridge with a groove in which at least one narrow groove extending along the longitudinal direction is formed in the ridge constituting the serration pattern. Based on the above, air that can give the surface of the ridge a variety and give a large intensity change to the reflected light, making the molding of the side wall inconspicuous and further improving the appearance of the side wall. The main purpose is to provide tires.

  According to the invention described in claim 1 of the present invention, a serrated pattern extending in the tire circumferential direction is formed on the surface of the tire sidewall portion by closely separating ridges extending in the tire radial direction in the tire circumferential direction. The ridge includes a grooved ridge in which at least one narrow groove extending along a longitudinal direction of the ridge is formed on a surface of the ridge.

  In the invention according to claim 2, in the grooved ridge, in the cross section perpendicular to the longitudinal direction, the outline of the tip region including the outermost point of the ridge that protrudes outward is convex toward the outer side of the tire. The pneumatic tire according to claim 1, which has an arc shape.

  According to a third aspect of the present invention, the grooved ridge has a semicircular shape in which a contour line excluding the narrow groove is convex toward the tire outer side in a cross section perpendicular to the longitudinal direction. This is a pneumatic tire.

  The invention according to claim 4 is the pneumatic tire according to claim 2 or 3, wherein the narrow groove is provided at a position excluding the outermost point of the ridge.

  According to a fifth aspect of the present invention, in the grooved ridge, in the cross section perpendicular to the longitudinal direction, the center line of the narrow groove connects the outermost point of the ridge and the center of the semicircular outline. The pneumatic tire according to claim 3, wherein the pneumatic tire forms an angle of 40 degrees or more and 60 degrees or less with respect to the ridge center line.

  According to a sixth aspect of the invention, the serration pattern includes a portion in which a ridge unit including at least two types of grooved ridges having different curvature radii of the contour line of the tip region repeatedly appears in the tire circumferential direction. The pneumatic tire according to any one of Items 2 to 5.

  The invention according to claim 7 is the pneumatic tire according to any one of claims 1 to 6, wherein the depth of the narrow groove is 0.1 to 0.5 times the raised height of the grooved ridge. It is.

  In the invention according to claim 8, the serration pattern includes a first pattern portion in which the grooved ridges are spaced in the tire circumferential direction, and a grooveless ridge in which the narrow grooves are not provided in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 7, wherein the spaced second pattern portions appear alternately in the tire circumferential direction.

  In the pneumatic tire of the present invention, the ridge constituting the serration pattern includes a grooved ridge in which at least one narrow groove extending along the longitudinal direction of the ridge is formed on the surface thereof. The grooved ridge, for example, can weaken the light that has entered the narrow groove when light is applied to the sidewall portion, and can diffuse the light irradiated to other portions in multiple directions. Thus, since the serration pattern of this embodiment gives a big strength change to reflected light, the concealment of the unevenness | corrugation formed in the side wall part and the visibility of a side design can be improved further.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partial perspective view of a pneumatic tire 1 of the present embodiment, FIG. 2 is a side view thereof, and FIG. 3 is a cross-sectional view taken along line AA of FIG.

  The pneumatic tire 1 is configured as a radial tire for a passenger car including a carcass 6 having a radial structure, for example. The carcass 6 includes a main body portion 6a extending between the pair of bead cores 5 and 5 in a toroidal manner, and a turn-up portion 6b connected to the main body portion 6a and wound around the bead core 5 from the inner side in the tire axial direction to the outer side. One carcass ply 6A is provided.

  On the surface of the sidewall portion 2 of the pneumatic tire 1, a serration pattern 4 having a width along the tire radial direction and extending in a belt shape in the tire circumferential direction is formed. The serration pattern 4 is formed by closely spaced ridges 3 made of small protrusions extending in the tire radial direction in the tire circumferential direction. As a preferred embodiment, each ridge 3 is provided so as to straddle the outer end 6be of the folded portion 6b of the carcass ply 6A in and out of the tire radial direction. This is desirable in that the stepped portion of the outer end 6be of the folded portion 6b is less noticeable on the outer surface 2a of the sidewall portion 2.

  In addition, the serration pattern 4 is desirably provided continuously in a ring over the entire circumference of the pneumatic tire 1, but it goes without saying that the serration pattern 4 may be partially interrupted. Further, as described above, a logo mark or a mark (both not shown) formed on the sidewall portion 2 may be provided on the serration pattern 4.

  As shown in FIG. 2, each ridge 3 of the present embodiment extends substantially parallel to the tire radial direction, but may be inclined with respect to the tire radial direction. In other words, “a ridge extending in the tire radial direction” can be restated as “a ridge having a tire radial direction component”.

  FIG. 3 shows a cross section perpendicular to the longitudinal direction of the ridge 3. The ridge 3 is a grooved ridge which is formed of a projecting body projecting at a raised height Wh, and has at least one (in this example, two) narrow grooves 7 extending along the longitudinal direction of the ridge on the surface. 3A is included. The contour line 8 of the grooved ridge 3A excluding the narrow groove 7 includes a tip region 8a including the outermost point 3b of the ridge which is located outward from the narrow groove 7 and protrudes outward, and the narrow groove 7 And an inner region 8b positioned more inwardly, and these are arranged on a substantially semicircle that is convex toward the outer side of the tire. However, as shown in FIG. 4, the cross-sectional outline of the ridge may be formed, for example, so that the root portion of the inner region 8b is linear.

  When the sidewall portion 2 is irradiated with light, the light that has entered the narrow groove 7 of the grooved ridge 3A is repeatedly reflected in the groove, and most of the light is absorbed. On the other hand, light irradiated to portions other than the narrow groove 7, for example, the tip region 8a, is reflected over a wide range. Therefore, by including the grooved ridge 3A in the serration pattern 4, the reflected light of the sidewall portion 2 gives a great change in strength, and the unevenness of the sidewall portion 2 becomes more inconspicuous, thereby making the sidewall portion 2 less noticeable. The appearance can be improved.

  In the ridges 3 including the grooved ridges 3A, the protruding height Wh and the protruding width Wr are preferably 0.4 mm or more, more preferably 0.5 mm or more, and preferably 0.8 mm or less. Preferably it is 0.7 mm or less. The raised height Wh and the raised width Wr are specified in a cross section perpendicular to the longitudinal direction of the ridge 3, and the raised height Wh is defined between the innermost surface 2a between the ridges 3 and 3 and the outermost point 3b of the ridge. The height is between. The raised width Wr is a distance between the root portions 3e and 3e of the ridge. When the raised height Wh is too small or the raised width Wr is too large, the unevenness concealing function of the sidewall portion 2 cannot be sufficiently expected. On the other hand, when the raised height Wh is too large or the raised width Wr is too small, stress tends to concentrate on the root portion of the ridge 3, and as a result, the durability of the ridge 3 may be reduced. In the present embodiment, since the contour line of the grooved ridge 3A excluding the narrow groove 7 is semicircular, the radius of curvature r of the tip region 8a is 0.4 to 0.8 mm, similar to the raised height Wh. It is set in the range of the degree.

  Further, as shown in FIG. 3, the distance Wi between the adjacent ridges 3, 3 is preferably 0.1 mm or more, more preferably 0.2 mm or more, and preferably 0.5 mm or less, more preferably Is preferably 0.4 mm or less. If the distance Wi between the ridges is too small, the molding becomes difficult and the manufacturing cost increases. On the contrary, if the distance Wi between the ridges 3 and 3 becomes excessively large, there is a possibility that the effect of making the appearance defect of the sidewall portion 2 inconspicuous is not sufficiently obtained.

  Further, the number N of the narrow grooves 7 formed per grooved ridge is not particularly limited. However, in order to give a large change to the reflected light from the serration pattern 4, preferably two or more, more Three or more are desirable. On the other hand, if the number N is increased, the durability of the grooved ridge 3A is lowered, and the processing of the narrow groove 7 may be difficult. From such a viewpoint, the number N of the narrow grooves is preferably 4 or less.

  As a preferred embodiment, in the grooved ridge 3A per groove, the sum of the groove widths Wg of the narrow grooves 7 is equal to the contour length of the grooved ridge 3A (the sum of the tip region 8a, the inner region 8b, and the groove width). It is desirable that it is 0.5 times or less, more preferably 0.4 times or less of the total (Wg). If the sum of the groove widths Wg of the narrow grooves 7 exceeds 0.5 times the contour length of the grooved ridge 3A, the rigidity of the grooved ridge 3A may be significantly reduced, and the ability to reflect light may be reduced. There is. On the other hand, when the total sum of the groove widths Wg of the narrow grooves 7 is smaller than the contour length of the grooved ridge 3A, it is difficult to cause a large intensity change in the reflected light. From such a viewpoint, the total sum of the groove widths Wg of the narrow grooves 7 is preferably 0.2 times or more, more preferably 0.3 times or more of the contour length of the grooved ridge 3A. The groove width Wg of the narrow groove 7 is a linear distance between the opening edges 7a and 7a.

  The depth Wd of the narrow groove 7 is preferably 0.1 to 0.5 times the ridge height Wh. When the depth Wd is less than 0.1 times the raised height Wh, it is difficult to obtain the effect of diversifying the shape due to the narrow grooves 7. Conversely, if the depth Wd of the narrow groove exceeds 0.5 times the raised height Wh, the rigidity of the grooved ridge 3A may be significantly reduced. In particular, the depth Wd of the narrow groove 7 is more preferably 0.20 times or more, more preferably 0.30 times or more, more preferably 0.30 times or more, more preferably 0.40 times or less, and still more preferably, the raised height Wh. 0.35 times or less is desirable.

  The cross-sectional shape of the narrow groove 7 is formed in a substantially rectangular shape in this embodiment. This is desirable in that the incident light is effectively attenuated and changes in intensity are applied. Moreover, since it is a simple shape, it is advantageous in terms of accuracy and cost in the processing step of the grooved ridge 3A. However, the cross section of the narrow groove 7 is not limited to such a substantially rectangular shape. For example, a tapered shape in which the groove width decreases toward the groove bottom, a U shape, a semicircular shape, or a triangular shape. Needless to say, various modifications can be made.

  The narrow groove 7 is preferably provided at a position excluding the ridge outermost point 3b. In other words, it is desirable that a part of the narrow groove 7 is not located on the outermost side of the ridge. If the narrow groove 7 is formed including the ridge outermost point 3b, most of the light is absorbed by the narrow groove, and the light reflection effect may be reduced. In particular, the narrow groove 7 has a cross section perpendicular to the longitudinal direction of the grooved ridge 3A, and the center line Rb of the narrow groove 7 is formed between the ridge outermost point 3b and the center Rc of the contour line 3c formed in a semicircular shape. It is desirable to have an angle θ of 40 degrees or more and 60 degrees or less with respect to the connected ridge center line Ra. Thereby, reflection of a wide range of light at the tip region 8a and absorption of light at the narrow groove 7 can be exerted in a balanced manner, and a greater intensity change can be given to the reflected light.

  As shown in FIG. 5, the serration pattern 4 includes a portion where the ridge unit 9 in which at least two types of grooved ridges 3A having different curvature radii r1 to r4 of the tip region 8a are arranged repeatedly appears in the tire circumferential direction. It is preferable. The ridge unit 9 of the present embodiment is configured by sequentially arranging first to fourth grooved ridges 3A1 to 3A4 having different curvature radii (r1> r2> r3> r4). The serration pattern including such a ridge unit 9 has grooved ridges 3A1 to 3A4 having different reflected light intensities arranged in the tire circumferential direction. This is desirable in that the unevenness of the portion 2 can be made inconspicuous. In order to exert this effect remarkably, it is desirable that the ridge unit 9 includes three or more types, more preferably four or more types having different curvature radii of the tip region 8a. It is desirable that the number is not more than 10, more preferably not more than 10, more preferably not more than 7. The ridge units 9 of the present embodiment are arranged so that the radii of curvature r1 to r4 gradually increase from the first grooved ridge 3A1 to the fourth grooved ridge 3A4, but the arrangement can be arbitrarily changed. .

  Further, as shown in FIG. 6, the serration pattern 4 can be implemented in various forms. That is, as shown in FIG. 6A, the serration pattern 4 may include grooved ridges 3A in which the positions of the narrow grooves 7 are different, and as shown in FIG. The serration pattern 4 may include a plurality of types of grooved ridges 3 </ b> A having different numbers of fine grooves 7.

  Further, as shown in FIG. 7, the serration pattern 4 is not provided with the fan-shaped first pattern portion 4A in which the grooved ridges 3A are closely spaced in the tire circumferential direction and the narrow groove 7. The grooveless ridges 3B may be formed so as to alternately appear in the tire circumferential direction with fan-shaped second pattern portions 4B that are closely spaced in the tire circumferential direction. In FIG. 7, for convenience, the grooved ridge 3A is indicated by a solid line, and the grooveless ridge 3B is indicated by a broken line. The serration pattern 4 includes the grooved ridge 3A and the grooveless ridge 3B having different reflection strengths, thereby further improving the concealment of the appearance defect of the sidewall portion 2 and the visibility of the side design. Is desirable. In this embodiment, the arc angle θa of the first pattern portion 4A centering on the tire rotation axis Tc is the same as the arc angle θb of the second pattern portion 4B, but each arc angle is the same. It may be different.

  Further, it is desirable that the narrow groove 7 extends over the entire length of the grooved ridge 3A. However, as shown in FIG. 8, the narrow groove 7 may be less than the entire length, and if necessary, It may be interrupted. Each grooved ridge 3A is formed simultaneously with the vulcanization of the tire, but the method of forming the narrow groove 7 is not particularly limited. That is, the narrow groove 7 may be formed by vulcanization, or may be formed by cutting or the like after vulcanization. As mentioned above, although the especially preferable form of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

Pneumatic tires (size 195 / 65R15) having serration patterns composed of ridges based on the specifications in Tables 1 and 2 were prototyped, and the appearance and mold workability of the sidewall portions were tested. Each ridge has a semicircular cross section. Therefore, the ridge width Wr and the radius of curvature of the tip region are equal to the raised height. As for the grooved ridge, a narrow groove was formed in the cross section of the square groove shown in FIG. The specifications were the same except for the items listed in the table.
The test method is as follows.

<Appearance of side wall>
The side wall portion of each sample tire was visually observed from various directions outside a sunny day, and the quality of the appearance of the side wall portion was evaluated by a five-point method based on the sensation of the observer. It shows that the external appearance of a sidewall part is so favorable that a numerical value is large.

<Mold workability and cost>
The moldability of each sample tire and the cost for processing were evaluated by a five-point method. The larger the value, the better the mold workability and cost. If the score is 2 or more, it is a range that can be put into practical use.
Tables 1 and 2 show the test results.

  As a result of the test, it was confirmed that the tire of the example significantly improved the appearance of the sidewall portion.

Next, in comparison with Example 1 having a serration pattern composed of the same grooved ridge, the effect of the serration pattern using a ridge unit (FIG. 5) combining a plurality of types of ridges was verified. The number of types was 10 and the radius of curvature of the tip region was changed as follows. In Examples 13, 14 and 15, type numbers 3, 5 and 7 were selected, and ridge units in which these were arranged in order were repeatedly arranged in the tire circumferential direction.
Type number 1: r1 = 0.40mm
Type number 2: r2 = 0.45mm
Type number 3: r3 = 0.50mm
Type number 4: r4 = 0.55mm
Type number 5: r5 = 0.60mm
Type number 6: r6 = 0.65mm
Type number 7: r7 = 0.70mm
Type number 8: r8 = 0.72mm
Type number 9: r9 = 0.75mm
Type number 10: r10 = 0.80mm
The raised height Wh of the ridge is equal to the radius of curvature, the groove width Wg of the fine groove is 0.30 mm, the groove depth Wd is 0.20 mm, the number of fine grooves is 2, and the angle with respect to the ridge center line of the fine groove is They were unified to 45 degrees.
Table 3 shows the test results.

  As a result of the test, it was confirmed that when the ridge unit was used, the appearance of the sidewall portion was further improved.

Furthermore, in comparison with Example 1 which has a serration pattern consisting of the same grooved ridge, the effect of the serration pattern (FIG. 7) having the first pattern portion and the second pattern portion was verified. The ridge height Wh is 0.60 mm, the groove width Wg of the narrow groove is 0.30 mm, the groove depth Wd is 0.20 mm, the number of narrow grooves is 1 and the angle of the narrow groove with respect to the ridge center line is 45 degrees. Unified.
Table 4 shows the test results.

It is a fragmentary perspective view of the pneumatic tire of this embodiment. It is the partial side view. It is an expanded sectional view showing a grooved ridge of this embodiment. It is sectional drawing of the grooved ridge which shows other embodiment. It is sectional drawing which shows one Embodiment of a ridge unit. (A), (b) is sectional drawing explaining arrangement | positioning of a grooved ridge. It is a partial side view of the pneumatic tire which shows other embodiment of this invention. It is. It is a perspective view of a grooved ridge showing another embodiment of the present invention.

Explanation of symbols

1 Pneumatic tire 2 Side wall 3 Ridge 3A Grooved ridge 4 Serration pattern 7 Narrow groove

Claims (8)

A pneumatic tire in which a serration pattern extending in a belt shape in the tire circumferential direction is formed by closely separating ridges extending in the tire radial direction on the surface of the tire sidewall portion in the tire circumferential direction,
The pneumatic tire according to claim 1, wherein the ridge includes a grooved ridge in which at least one narrow groove extending along a longitudinal direction of the ridge is formed on a surface of the ridge.   2. The grooved ridge has an arc shape in which a contour line of a tip region including an outermost point of the ridge that protrudes outward in a cross section perpendicular to a longitudinal direction of the grooved ridge is convex toward the tire outer side. Pneumatic tire.   The pneumatic tire according to claim 2, wherein the grooved ridge has a semicircular shape in which a contour line excluding the narrow groove is convex toward the tire outer side in a cross section perpendicular to the longitudinal direction.   The pneumatic tire according to claim 2 or 3, wherein the narrow groove is provided at a position excluding the outermost point of the ridge.   The grooved ridge has a cross-section perpendicular to the longitudinal direction, and the center line of the narrow groove is 40 degrees or more with respect to the ridge center line connecting the outermost point of the ridge and the center of the semicircular outline. The pneumatic tire according to claim 3, wherein the pneumatic tire forms an angle of 60 degrees or less.   6. The serration pattern includes a portion in which a ridge unit including at least two types of grooved ridges having different curvature radii of a contour line of the tip region repeatedly appears in a tire circumferential direction. Pneumatic tires.   The pneumatic tire according to any one of claims 1 to 6, wherein a depth of the narrow groove is 0.1 to 0.5 times a raised height of the grooved ridge.   The serration pattern includes a first pattern portion in which the grooved ridges are spaced in the tire circumferential direction and a second pattern portion in which the grooveless ridges without the narrow grooves are spaced in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 7, wherein and appear alternately in the tire circumferential direction.

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