JP6517673B2 - Pneumatic tire and its carcass ply member - Google Patents

Description

  The present invention relates to a carcass ply member used for a pneumatic tire, and a pneumatic tire using the same.

  In a pneumatic tire, a carcass ply as a reinforcing material embedded in the inside thereof is generally configured to be rolled up from the inside in the tire width direction to the outside so that an end thereof wraps around a bead core. On the other hand, Patent Document 1 proposes a configuration in which a carcass ply is wound inward from the outer side in the tire width direction. According to this configuration, the distribution of tension applied to the carcass ply is changed, and the tension at a position that easily contributes to the tire rigidity can be increased, and the steering stability can be improved.

  However, the configuration in which the carcass ply is wound inward from the outer side in the tire width direction is winding in a direction in which the circumferential length is narrowed, so wrinkles are easily generated in the winding portion and the cord interval becomes uneven. It becomes a factor of lowering, separation occurs at the winding end, and becomes a factor of lowering the durability.

  By the way, in the patent documents 2 and 3, in order to control the separation resulting from the cut end of the carcass cord which constitutes a carcass ply, between the both via the turnback part which arranged the carcass cord in the bead part on both sides. It is known to construct by means of a continuous cord which is reciprocated. However, these documents disclose that the carcass cords are formed of a continuous cord in a so-called core manufacturing method in which a tire component such as a carcass ply is attached to the outer surface of a hard core to form a green tire. The cords are arranged in parallel at equal intervals, and therefore, it is not possible to suppress separation at the winding end when winding the carcass ply from the outer side in the tire width direction to the inner side as described above.

Unexamined-Japanese-Patent No. 2015-105000 JP 2000-301912 A Unexamined-Japanese-Patent No. 2004-224072

  In view of the above points, the present invention suppresses carcass cords from becoming uneven at the winding-up portion of the carcass ply, suppresses the reduction in rigidity of the side portion, and can improve the durability. It aims at providing a ply member and a pneumatic tire using the same.

  First, the present embodiment is a pneumatic tire comprising a sheet having a longitudinal direction disposed along the circumferential direction of the tire and a lateral direction disposed along the tire meridian, and having a carcass cord covered with rubber. In the carcass ply member for carcass, the carcass cord is composed of one or three cords extending in the longitudinal direction while reciprocating between the both ends via the folded portions located at both ends in the lateral direction of the sheet. A carcass ply member for a pneumatic tire, wherein the cord is disposed in a tapered shape in which the cord interval decreases from the folded portion to the opposite lateral end of the seat.

  The present embodiment secondly includes a pair of left and right beads including a bead core, and a carcass ply bridged between the pair of bead cores, and the carcass ply extends around the pair of bead cores from the tire width direction outer side. A pneumatic tire which is rolled up inward in the tire width direction, wherein the carcass ply is formed of the carcass ply member described above.

  Third, the present embodiment thirdly includes a pair of left and right beads including a bead core, and a carcass ply bridged between the pair of bead cores, wherein the carcass ply extends around the pair of bead cores from the tire width direction outer side. It is a manufacturing method of the pneumatic tire by which it rolls up to tire width direction inner side, Comprising: It is in the manufacturing method of a pneumatic tire which forms the said carcass ply using said carcass ply member.

  According to the present embodiment, since the cord interval can be prevented from becoming uneven at the winding-up portion of the carcass ply, it is possible to suppress the reduction in rigidity of the side portion and to improve the durability.

1 is a half sectional view of a pneumatic tire according to an embodiment. FIG. 2 is an enlarged cross-sectional view around a bead portion in FIG. (A) A plan view schematically showing a carcass ply member according to an embodiment, (B) an enlarged view of its III-A portion, and (C) an enlarged view of its III-B portion. (A) A plan view schematically showing a carcass ply member according to another embodiment, (B) an enlarged view of a portion IV-C thereof.

  Hereinafter, the present embodiment will be described with reference to the drawings.

  The pneumatic tire T of the embodiment shown in FIG. 1 is a pneumatic radial tire for a passenger car, and includes a tread portion 1 constituting a contact surface and a pair of left and right side portions 2.

  The side portion 2 includes a bead portion 30 on the inner peripheral side in the tire radial direction, and a sidewall portion 20 interposed between the bead portion 30 and the tread portion 1. In the bead portion 30, a bead 33 composed of an annular bead core 31 made of bead wire and a bead filler 32 joined and integrated to the outer peripheral surface of the bead core 31 is embedded. The bead filler 32 is made of hard rubber and has a triangular cross-sectional shape that narrows toward the tip end.

  In the tire T, a carcass ply 4 bridged between a pair of left and right bead cores 31 is embedded. The carcass ply 4 extends from the tread portion 1 to the side portions 2 on both sides, and both ends thereof are wound up and locked by the bead core 31. Therefore, the carcass ply 4 includes a toroidal main body 41 extending between a pair of bead cores 31 and a winding portion 42 wound up around the bead cores 31 at both ends of the main body 41. The carcass ply 4 is formed by rubber-coating a carcass cord, and the carcass cord is disposed so as to be substantially perpendicular to the circumferential direction of the tire, and in this example, has a single-layer structure consisting of one ply .

  As shown in FIG. 2, the carcass ply 4 has its both ends rolled up or turned up from the outside in the tire width direction X around the bead core 31 through the tire outer surface side of the bead filler 32. . The winding portion 42 extends outward in the tire radial direction Y inside the tire 33 in the tire width direction X of the bead 33. In this example, the end (outer end in the tire radial direction Y) 43 of the winding portion 42 extends beyond the outer peripheral surface 31 A of the bead core 31 to the bead filler 32, and the tire of the bead filler 32 It terminates inside the tire radial direction Y with respect to the radial direction Y outer end 32A.

  An inner liner 5 is provided on the inner surface of the tire as a gas barrier rubber layer. The inner liner 5 is disposed on the inner circumferential side of the carcass ply 4. Both ends of the inner liner 5 are wound up around the bead core 31 from the inside to the outside in the tire width direction X. Both ends of the inner liner 5 extend between the bead core 31 and the carcass ply 4 around the bead core 31.

  A belt 11 is disposed on the outer peripheral side of the carcass ply 4 in the tread portion 1. The belt 11 is formed of one or a plurality of belt layers formed by inclining a belt cord at a constant angle with respect to the tire circumferential direction, and in this example, is configured of two belt layers. A tread rubber 13 is provided on the outer peripheral side of the belt 11 via a belt reinforcing layer 12.

  A sidewall rubber 21 is provided on the tire outer surface side of the carcass ply 4 in the sidewall portion 20. The bead portion 30 is provided with a rubber chafer 34 so as to cover the carcass ply 4 and the inner liner 5 around the bead core 31.

  The structure of the carcass ply member 6 forming the carcass ply 4 is shown in FIG. The carcass ply member 6 has a longitudinal direction A disposed along the tire circumferential direction and a lateral direction B disposed along the tire meridian direction (direction orthogonal to the tire circumferential direction on the tire surface). 60, that is, a strip-shaped member having the lateral direction B as the width direction and the longitudinal direction A as the longitudinal direction. The carcass ply member 6 is obtained by, for example, coating a carcass cord 61 such as an organic fiber cord with an unvulcanized rubber 62, and the carcass cord 61 is embedded in a sheet made of the unvulcanized rubber 62.

  The carcass cords 61 extend in the longitudinal direction A of the sheet 60 while reciprocating between the both ends 60A and 60B via the folding parts 63 located at the lateral ends 60A and 60B of the sheet 60, and three cords 61A , 61B, 61C. That is, the carcass cord 61 includes three cords 61A, 61B, 61C, and each cord extends along the lateral direction B of the sheet 60 and is folded without interruption at both end portions 60A, 60B, thereby meandering. It extends in the longitudinal direction A. In FIG. 3A, in order to make it easy to distinguish three codes, one code 61A is shown by a solid line, and the remaining two codes 61B and 61C are shown by two kinds of dotted lines. .

  The carcass cords 61 have the folded portions 63 as the bottom side 65A by inclining the lateral extension portions 64 of the respective cords 61A, 61B, 61C with respect to the lateral direction B, and the side opposite to the sheet 60 from the bottom side 65A. The cords 61A, 61B, 61C are disposed in a tapered shape (or triangular shape) 65 in which the cord interval decreases, preferably gradually, down to the direction end portions 60A, 60B. Specifically, the tapered shape 65X in which the cord interval gradually decreases from the folded portion 63 to the other lateral end 60B at the lateral one end 60A of the sheet 60, and from the folded portion 63 at the lateral other end 60B to the lateral one end 60A A tapered shape 65Y in which the cord interval gradually decreases is formed, and both 65X and 65Y are alternately arranged adjacent to each other in the longitudinal direction A. In this example, the tapered shape 65 is formed to be gradually narrower in width from the base to the apex, with the folded portion 63 as the base and the later-described intersection 66 located at the opposite lateral end as the apex.

  Here, the tapered shape 65 is not limited to a shape in which the cord interval decreases at a constant rate over the entire width in the lateral direction B. For example, a region where the cord interval is constant may partially exist. Further, the laterally extending portion 64 is a cord portion located between the folded portions 63, 63 of the lateral end portions 60A, 60B and connecting the two, and in the lateral direction B in each of the cords 61A, 61B, 61C. It is an extending part.

  The folded portions 63A, 63B and 63C of the three cords 61A, 61B and 61C are sequentially arranged adjacent to each other in the longitudinal direction A of the sheet 60, as shown in FIG. 3 (B). The tapered shape 65 is a linear shape extending from a folded portion 63A of one cord 61A and two folded portions 63B and 63C of two other cords 61B and 61C adjacent to both sides of the folded portion 63A. And the laterally extending portions 64B and 64C.

  Moreover, the folding | returning part 63 of each code | cord | chord 61A, 61B, 61C is formed in the curve shape by circular arc. In this example, the folded back portion 63 has a semicircular shape, so that the cords 61A, 61B, 61C are folded back in a U-shape at both lateral end portions 60A, 60B of the sheet 60. The radius of curvature of the folded portion 63 is preferably 1/2 or more of the cord interval at both lateral end portions 60A and 60B described later, and is set to 1/2 in this example.

  More specifically, the carcass cord 61 is configured as follows. As shown by an arrow P in FIG. 3A, the first cord 61A is extended while being inclined from the one end 60A to the other end 60B in the lateral direction, and is U-shaped without interruption at the other end 60B. After being folded, it is extended while being inclined from the other end 60B to the one end 60A, and is folded back in a U-shape without interruption at the one end 60A. This is repeated in the vertical direction A with the basic configuration. The laterally extending portion 64 is inclined in a direction away from the immediately preceding laterally extending portion 64, and the inclination width V with respect to the lateral direction B is in the longitudinal direction A of the U-shaped folded portion 63. It is set to 1/2 of the width W.

  The second cord 61B and the third cord 61C also have the same basic configuration as the first cord 61A, and reciprocate between the one end 60A and the other end 60B in the lateral direction. The second and third cords 61A, 61B, 61C are all reciprocated with the same pitch (ie, wavelength) and with a phase shift of 1/3 pitch. Thus, the folded portions 63A, 63B, 63C of the three cords 61A, 61B, 61C are arranged adjacent to each other without a gap in the longitudinal direction A of the sheet 60.

  Further, the cords 61A, 61B, 61C intersect at both lateral end portions 60A, 60B of the sheet 60, and in this example, as shown in FIG. The codes 61A, 61B, 61C cross each other. As described above, since the two cords become an integral cord at the crossing portion 66 by being rubber-coated in a state in which the cords cross each other, the cord interval at both lateral ends 60A and 60B is U-shaped The width (cord center distance) W in the vertical direction A of the folded portion 63 is obtained. The crossing portion 66 may not necessarily be set to the folded portion 63. For example, a gap may be provided between adjacent folds 63 adjacent to each other in the longitudinal direction A, and in this case, the intersection 66 is set to the lateral extension 64. However, since the crossing portion 66 is provided at both lateral end portions 60A and 60B of the sheet 60, even when a gap is provided between the folded portions 63 and the code center distance F is equal to the distance between the cord centers It is preferable that it is 1/5 or less of the width W of.

  The distance between two adjacent cords in the longitudinal direction A gradually decreases from one end to the opposite end in the lateral direction B by the disposition of the tapered shape 65 described above, and the opposite end At the intersection 66, it becomes zero. Therefore, the cord spacing at both ends 60A and 60B in the lateral direction B is wider than the cord spacing at the central portion in the lateral direction B and is 1.5 to 2.5 times the cord spacing at the center Preferably, more preferably twice. In this example, since the cord spacing at both ends in the lateral direction B is the above-described width W, as shown in FIG. 3C, the cord spacing at the center in the lateral direction B is W / 2. .

  The method of manufacturing the pneumatic tire T according to the present embodiment can be manufactured by a known method except that the carcass ply member 6 described above is used as a carcass ply member forming the carcass ply 4. For example, as disclosed in JP-A-2014-125120, an inner liner is attached on a tire forming drum, a bead is placed on the inner liner, a carcass ply member is attached on the bead, and a side is further provided. After affixing a wall rubber or the like, both ends of the carcass ply member are folded back to the inner peripheral side of the bead to produce a primary molded body. At that time, the carcass ply member 6 may be pasted on the inner liner with the longitudinal direction A disposed in the tire circumferential direction and the transverse direction B in the tire meridian direction. Thereafter, the primary molded product is expanded in the radial direction, and then a belt and tread rubber are attached, and then both ends of the carcass ply member are wound up and crimped to the inside of the bead. By vulcanizing and molding the green tire obtained in this manner, a pneumatic tire is obtained.

  According to the present embodiment as described above, the carcass cord 61 is constituted by the cords 61A, 61B, 61C which are continuous while being folded back at the lateral end portions 60A, 60B of the sheet 60, thereby making tension distribution uniform and rigidity. It can contribute to improvement.

  Further, by arranging the carcass cords 61 in the tapered shape 65 as described above, the cord interval is narrow at the central portion in the lateral direction B, and the cord interval is wide at both end portions in the lateral direction B. When a tire T is manufactured using the carcass ply member 6 having such a cord arrangement, the cord interval becomes wider at the central portion in the lateral direction B disposed in the tread portion 1 and is disposed in the side portion 2 At both ends in the lateral direction B, the cord spacing is narrowed, so when the tire T is formed, the cord spacing is uniformed overall, which leads to an improvement in rigidity.

  Further, in the structure in which the carcass ply 4 is wound inward from the outer side in the tire width direction X, the cord interval is too tight due to the cord coming up by winding, and wrinkles easily occur, but according to this embodiment, the carcass ply By widening the cord intervals at both ends in the lateral direction B in the member 6, it is difficult to cause wrinkles at the time of winding up, and it can be suppressed that the cord intervals become uneven at the winding up section 42. It can be improved. In addition, by equalizing the cord interval in the winding-up portion 42, it is possible to reduce the factor of the decrease in the rigidity of the side portion 2.

  Further, in the carcass ply member 6, the folded portions 63 of the cords 61A, 61B, 61C are formed in a curved shape, so that when the cords come close to each other at both ends in the lateral direction B when winding up at the time of tire molding By deforming the portion 63 into a flattened shape so that the arc extends outward, it is possible to narrow the cord interval while maintaining the curved shape. Therefore, the cord intervals can be narrowed at equal intervals, so that the above-described rigidity and durability improvement effect can be enhanced.

  In the above embodiment, the carcass cords 61 are constituted by the three cords 61A, 61B and 61C, but may be constituted by one cord 61D. FIG. 4 shows an example thereof.

  In the carcass ply member 6A shown in FIG. 4, the carcass cord 61 reciprocates between the both end portions 60A and 60B via the folded back portions 63 located at the lateral end portions 60A and 60B of the seat 60 in the longitudinal direction A. It comprises one extending cord 61D. The cord 61D has the folded portion 63 as the bottom 65A by inclining the lateral extension 64 with respect to the lateral direction B, and the cord 61D extends from the bottom 65A to the opposite lateral end 60A, 60B of the sheet 60. It is disposed in a tapered shape 65 in which the distance gradually decreases. Specifically, a tapered shape 65X whose bottom is the folded portion 63 at one end 60A in the lateral direction and a tapered shape 65Y whose bottom is the folded portion 63 at the other end 60B in the lateral direction are alternately adjacent in the longitudinal direction A. It is arranged. In this example, the tapered shape 65 is formed to have a width gradually decreasing from the base to the apex, with the folded portion 63 as the base and the later-described abutment part 67 located at the opposite lateral end as the apex. .

  As shown in FIG. 4B, the folded portions 63 of the cord 61D are sequentially arranged adjacent to each other in the longitudinal direction A, and the tapered shape 65 includes a curved folded portion 63 and two extending from the folded portion 63. It is formed by the linear horizontal extension parts 64 and 64 of a book.

  More specifically, as shown by an arrow P in FIG. 4A, the cord 61D is extended while being inclined from the one end 60A to the other end 60B in the lateral direction, and U-shaped without interruption at the other end 60B. After being folded back into a shape, it is extended while being inclined from the other end 60B to the one end 60A, and is folded back into a U shape without interruption at the one end 60A. This is repeated in the vertical direction A with the basic configuration. The laterally extending portion 64 is inclined in a direction approaching the immediately preceding laterally extending portion 64, and the inclination width V with respect to the lateral direction B is in the longitudinal direction A of the U-shaped folded portion 63. It is set to 1/2 of the width W. Thus, the folded back portion 63 of the cord 61D is disposed adjacent to the sheet 60 in the longitudinal direction A without a gap.

  Further, at both lateral end portions 60A and 60B of the sheet 60, the cords 61D adjacent to each other in the longitudinal direction A are in contact with each other. In this example, as shown in FIG. The contact portion 67 is formed by the mutual contact between the cords 61D. The cords 61D may not necessarily be in contact with each other, and a gap may be provided between the folded portions 63 adjacent to each other in the longitudinal direction A to make them approach each other. However, it is preferable that the cord center distance F between adjacent folded portions 63 is 1⁄5 or less of the width W of the folded portions 63.

  In the embodiment shown in FIG. 4 as well, by arranging the cords 61D in the tapered shape 65 as described above, the cord spacing is narrow at the central portion in the lateral direction B, and the cord spacing is wide at both ends in the lateral direction B. As a result, when the tire T is reached, the cord interval can be equalized overall, leading to an improvement in rigidity. Further, in the structure in which the carcass ply 4 is wound inward from the outer side in the tire width direction X, wrinkles during winding are less likely to occur, and uneven cord intervals at the winding portion 42 can be suppressed. While being able to improve nature, the factor of the rigid fall of side part 2 can be reduced. In the embodiment shown in FIG. 4, the other configurations and effects are the same as those of the embodiment shown in FIGS.

  In the above embodiment, the cords are provided at the lateral extending portions 64 of the cords 61A, 61B, 61C, 61D inclining with respect to the lateral direction B during the reciprocation process, but only one of the reciprocation processes is inclined. And the other may extend parallel to the lateral direction B. However, it is preferable to incline both in the process of reciprocation because the directivity can be eliminated.

  In order to show the effect of the said embodiment, the pneumatic radial tire (size: 195 / 65R15) for passenger cars of Example 1, 2 and Comparative Example 1, 2 was made as an experiment. The tire of Example 1 is a tire according to the embodiment illustrated in FIGS. 1 to 3 (width W of the folded portion 63 in the longitudinal direction A = 1.2 mm). The tire of Example 2 is a tire of the embodiment shown in FIG. 4 (width W = 1.2 mm in the longitudinal direction A of the folded back portion 63). In the tire of Comparative Example 1, as a carcass ply member, one in which a large number of cords are aligned in parallel (one having a cut end of the cord at both end portions in the lateral direction) is used (cord drive density = 28) / 25 mm), a tire having a structure in which the carcass ply member is wound up from the inside to the outside in the tire width direction around the bead core. The tire of Comparative Example 2 is a tire having a structure in which the same carcass ply member as that of Comparative Example 1 is rolled up from the outside in the tire width direction to the inside around the bead core as in Example 1. In all the examples, the other configurations are the same.

  For each of these tires, steering stability and durability, longitudinal stiffness and lateral stiffness were evaluated. Each evaluation method is as follows.

  Steering stability: The driver performs a sensory evaluation of steering stability on a dry road by running a test vehicle (domestic 2L sedan) equipped with each tire at a speed of 100 km / h. It evaluated by the index which made evaluation 100. The larger the index is, the better the steering stability is.

  Durability: The running distance until the tire failed was measured by a test method based on FMVSS 139, and the measurement result of Comparative Example 1 was evaluated as an index of 100. The larger the index, the better the durability.

  Longitudinal stiffness: Using a 50t stiffness tester, measure the amount of longitudinal deflection of the tire when the predetermined load is increased or decreased with respect to the reference load in the vertical direction, and divide the increased or decreased amount of load by the amount of longitudinal deflection. The calculated value was calculated. The evaluation result is expressed as an index with the result of Comparative Example 1 being 100, and indicates that the larger the index is, the higher the longitudinal rigidity is.

Lateral rigidity: With a standard load applied to the tire, a lateral force of 30% of the standard load is further applied to the tire using a 50 t stiffness tester, and the lateral deflection is measured. The value divided by the amount of deflection was created. The evaluation result is expressed as an index with the measurement result of Comparative Example 1 taken as 100, and indicates that the lateral rigidity is higher as the index is larger.

  The results are as shown in Table 1. In Comparative Example 2 in which the winding structure of the carcass ply is changed from the outer side to the inner side in the tire width direction as compared with Comparative Example 1, the steering stability is improved, but wrinkles enter the winding portion and the cord interval becomes uneven. As a result, the durability was inferior, and the improvement effect of longitudinal and lateral rigidity was also small. On the other hand, in Examples 1 and 2, in the configuration in which the carcass ply is wound inward from the outer side in the tire width direction, the carcass cords are continuous cords as in the above embodiment and the tapered shape is arranged with different cord intervals. As a result, the durability can be improved, and the longitudinal rigidity and the lateral rigidity are improved, and the steering stability is significantly improved.

  While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and the equivalents thereof as well as included in the scope and the gist of the invention.

T: pneumatic tire, 2: side portion, 31: bead core, 33: bead 4: carcass ply, 42: winding up portion 6: carcass ply member, 60: sheet, 60A, 60B: lateral end 61 of sheet: carcass Code, 61A, 61B, 61C, 61D: Code 63: Folded portion, 64: Laterally extending portion, 65: Taper shape, 65A: Bottom side,
A: vertical direction, B: horizontal direction

Claims (5)

A carcass ply member for a pneumatic tire, comprising a sheet having a longitudinal direction disposed along the circumferential direction of the tire and a lateral direction disposed along the tire meridian direction, and having a carcass cord rubber-coated,
The carcass cord is made of one or three cords extending in the longitudinal direction while reciprocating between the both ends via the folded portions located at both lateral ends of the sheet, and the folded portion from the folded portion The cords are arranged in a tapered configuration in which the cord spacing decreases towards the opposite lateral end,
Carcass ply member for pneumatic tires.   The carcass cord is composed of three cords, and the folded back portions of the three cords are sequentially arranged in the longitudinal direction of the sheet, and the tapered shape is a folded back portion of one cord and both sides of the folded back portion The carcass ply member for a pneumatic tire according to claim 1, formed by: a lateral extension portion extending from a turnback portion of two other cords adjacent to each other.   The carcass ply member for pneumatic tires according to claim 1 or 2, wherein the folded portion of the cord is formed in a curved shape. A pair of left and right beads including a bead core, and a carcass ply bridged between the pair of bead cores, wherein the carcass ply is wound around the pair of bead cores from the outer side in the tire width direction to the inner side in the tire width direction. A pneumatic tire,
The pneumatic tire in which the said carcass ply was formed with the carcass ply member of any one of Claims 1-3. A pair of left and right beads including a bead core, and a carcass ply bridged between the pair of bead cores, wherein the carcass ply is wound around the pair of bead cores from the outer side in the tire width direction to the inner side in the tire width direction. A method of manufacturing a pneumatic tire, comprising
The manufacturing method of a pneumatic tire which forms the said carcass ply using the carcass ply member of any one of Claims 1-3.

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