JP2008279821A - Pneumatic tire and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving its durability and to provide a manufacturing method for the pneumatic tire. <P>SOLUTION: This pneumatic tire has a belt layer arranged on an outer side in the radial direction of the tire of a carcass layer, a first belt cover layer 8 arranged by covering a central part on an outer side in the radial direction of the tire in at least the belt layer, and a second belt cover layer 9 arranged by covering an end part on the outer side in the radial direction of the tire in the belt layer. The second belt cover layer 9 has a higher modulus of elasticity than that of the first belt cover layer 8 and is arranged by winding it around the belt layer annularly in a scope of one round or more and less than two rounds. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve the durability of the tire and a method for manufacturing the pneumatic tire.

  In recent pneumatic tires, in order to reduce road noise, a first belt cover layer having a low elastic modulus is disposed in the central region of the belt layer, and a second belt cover layer having a high elastic modulus only at both end regions thereof. Is placed. The first belt cover layer is made of, for example, a belt cover material made of nylon fiber. The second belt cover layer is made of a belt cover material made of, for example, polyethylene naphthalate fiber, aramid fiber, polyketone fiber, or the like.

  Here, in the above configuration, since the second belt cover layer has a high elastic modulus, it is difficult for the end portion of the belt layer to follow the tire diameter growth during vulcanization of the tire. For this reason, there is a problem that a vulcanization failure occurs, and separation occurs in the tread rubber at the end of the belt layer, resulting in a decrease in tire durability.

  In addition, the technique described in patent document 1 is known for the conventional pneumatic tire which has this structure.

Japanese Patent No. 3145902

  An object of the present invention is to provide a pneumatic tire that can improve the durability of the tire and a method for manufacturing the pneumatic tire.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a belt layer disposed on the outer side in the tire radial direction of the carcass layer and at least a central portion on the outer side in the tire radial direction of the belt layer. A pneumatic tire having a belt cover layer and a second belt cover layer disposed so as to cover an end of the belt layer on the outer side in the tire radial direction, wherein the second belt cover layer is the first belt cover. The elastic layer has an elastic modulus higher than that of the layer, and is wound around the belt layer in a range of not less than 1 and less than 2 rounds.

  In this pneumatic tire, the second belt cover layer is wound around the end of the belt layer in a range of not less than 1 and less than 2 laps, so the second belt cover layer is continuously wound multiple times. Compared with the structure currently provided, the restraint force of the edge part of the belt layer by a 2nd belt cover layer is reduced. Then, when the diameter of the green tire expands during tire vulcanization, the start and end portions of the second belt cover layer can be displaced in the tire circumferential direction, so that the coating between the second belt cover layer and the belt layer Rubber thickness is ensured properly. Thereby, the separation of the tread rubber at the end portion of the belt layer is effectively reduced, and there is an advantage that the durability performance of the tire is improved.

  In the pneumatic tire according to the present invention, when the tire is in an unvulcanized state, a lap width t between the start end portion and the end end portion of the second belt cover layer is larger than a circumferential length T of the second belt cover layer. 0.003 ≦ t / T.

  In this pneumatic tire, since the lap width t of the second belt cover layer is optimized, there is an advantage that the high-speed durability performance and uniformity of the tire are appropriately maintained.

  In the pneumatic tire according to the present invention, the lap width t between the start end portion and the end end portion of the second belt cover layer is t / T with respect to the circumferential length T of the second belt cover layer. ≦ 0.50.

  In this pneumatic tire, since the binding force of the end of the belt layer by the second belt cover layer is optimized, the coating rubber between the second belt cover layer and the belt layer in the vulcanization process of the tire The wall thickness is secured. Thereby, there exists an advantage by which the separation of the tread rubber 6 in the edge part of a belt layer is reduced effectively.

  In the pneumatic tire according to the present invention, the first belt cover layer has a jointless structure.

  In this pneumatic tire, since the first belt cover layer has a jointless structure, there is an advantage that the splice component is reduced and the uniformity of the tire is improved.

  In the pneumatic tire according to the present invention, the first belt cover layer is disposed outside the belt layer in the tire radial direction, and the second belt cover layer is disposed outside the first belt cover layer.

  In this pneumatic tire, since the second belt cover layer has a high elastic modulus and is wound around the belt layer in a range of 1 round or more and less than 2 rounds, when the tire diameter grows during vulcanization of the tire, The second belt cover layer is greatly displaced in the tire circumferential direction. On the other hand, the first belt cover layer having a low elastic modulus extends more greatly when the tire diameter grows at the time of vulcanization of the tire, and thus its position is difficult to be displaced. Therefore, when the first belt cover layer is sandwiched between the belt layer and the second belt cover layer, the influence of the belt angle of the belt layer due to the displacement of the second belt cover layer during vulcanization of the tire is reduced. The Thereby, there exists an advantage by which the uniformity of a tire is maintained appropriately.

  In the pneumatic tire according to the present invention, the elongation ratio of 2.0 [cN / dtex] of the belt cover material constituting the first belt cover layer is 4.0 [%] or more and less than 10.0 [%]. And the elongation ratio of 2.0 [cN / dtex] of the belt cover material constituting the second belt cover layer is in the range of 1.5 [%] or more and less than 4.0 [%]. It is in.

  In this pneumatic tire, since the elastic moduli of the first belt cover layer and the second belt cover layer are optimized, road noise at a mid-frequency (200 [Hz] to 400 [Hz]) is effectively reduced. There are advantages.

  In the pneumatic tire according to the present invention, the belt cover material of the first belt cover layer is made of nylon fiber, and the belt cover material of the second belt cover layer is polyester fiber, polyketone fiber, lyocell fiber, aramid It consists of a composite fiber formed by twisting a fiber, an aramid fiber and a nylon fiber, or a composite fiber formed by twisting a polyketone fiber and a nylon fiber.

  In this pneumatic tire, since the material (elastic modulus) of the first belt cover layer and the second belt cover layer is optimized, there is an advantage that road noise at the mid frequency is effectively reduced.

  In the pneumatic tire according to the present invention, the belt layer is made of a steel belt ply.

  In this pneumatic tire, the rigidity of the belt layer is increased as compared with a configuration in which the belt layer is made of an organic fiber belt ply. Thereby, there exists an advantage which the high-speed durability performance of a tire improves.

  In the pneumatic tire according to the present invention, the maximum width Wb of the belt layer and the total width Wc of the second belt cover layer disposed at one end of the belt layer are 0.02 ≦ Wc / It has a relationship of Wb ≦ 0.35.

  In this pneumatic tire, since the ratio Wc / Wb between the maximum width Wb of the belt layer and the total width Wc of the second belt cover layer is optimized, there is an advantage that road noise at the mid frequency is effectively reduced. is there. Moreover, there is an advantage that the riding comfort performance of the tire is maintained appropriately.

  The pneumatic tire according to the present invention includes a distance Xb from the tread portion center crown CL to the maximum width position of the belt layer, and an end portion of the second belt cover layer on the outer side in the tire width direction from the tread portion center crown CL. To the distance Xc is 0.70 ≦ Xb / Xc ≦ 1.20.

  In this pneumatic tire, since the positional relationship between the end portion of the belt layer and the second belt cover layer is optimized, there is an advantage that road noise at the mid-frequency is effectively reduced, and the tire uniformity is also improved. There is an advantage that is maintained.

  The pneumatic tire manufacturing method according to the present invention includes a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and a first belt disposed so as to cover at least a central portion on the outer side in the tire radial direction of the belt layer. A method for manufacturing a pneumatic tire, comprising: a cover layer; and a second belt cover layer disposed so as to cover an end portion of the belt layer on the outer side in the tire radial direction, wherein the second belt cover layer is the first belt. It has a higher elastic modulus than the elastic modulus of the cover layer, and the green tire is expanded in diameter at the time of tire vulcanization by being arranged around the belt layer in a range of not less than 1 and less than 2 laps. Sometimes, the start and end portions of the second belt cover layer are displaced in the tire circumferential direction.

  In this method for manufacturing a pneumatic tire, the second belt cover layer of the pneumatic tire is wound around the end of the belt layer so as to be wound in a range of 1 round or more and less than 2 rounds. Compared with a configuration (not shown) wound continuously around a plurality of circumferences, the binding force at the end of the belt layer by the second belt cover layer is reduced. Then, when the diameter of the green tire expands during tire vulcanization, the start and end portions of the second belt cover layer can be displaced in the tire circumferential direction, so that the coating between the second belt cover layer and the belt layer Rubber thickness is ensured properly. Thereby, the separation of the tread rubber at the end portion of the belt layer is effectively reduced, and there is an advantage that the durability performance of the tire is improved.

  In the pneumatic tire according to the present invention (pneumatic tire manufacturing method), the second belt cover layer is wound around the end portion of the belt layer in a range of 1 round or more and less than 2 rounds. Compared to the configuration in which the belt cover layer is continuously wound around a plurality of circumferences, the binding force at the end of the belt layer by the second belt cover layer is reduced. Then, when the diameter of the green tire expands during tire vulcanization, the start and end portions of the second belt cover layer can be displaced in the tire circumferential direction, so that the coating between the second belt cover layer and the belt layer Rubber thickness is ensured properly. Thereby, the separation of the tread rubber at the end portion of the belt layer is effectively reduced, and there is an advantage that the durability performance of the tire is improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. 2-6 is explanatory drawing which shows the belt cover layer of the pneumatic tire described in FIG. 7-15 is explanatory drawing which shows the modification of the belt cover layer described in FIG. FIGS. 16-19 is a table | surface which shows the result of the performance test of the pneumatic tire concerning the Example of this invention.

[Pneumatic tire]
The pneumatic tire 1 includes a bead core 2, a bead filler 3, a carcass layer 4, a belt layer 5, a tread rubber 6, and a sidewall rubber 7 (see FIG. 1). The bead core 2 has an annular structure and is configured as a pair of left and right. The bead filler 3 is disposed on the outer periphery of the bead core 2 in the tire radial direction and reinforces the bead portion of the tire 1. The carcass layer 4 is bridged in a toroidal shape between the left and right bead cores 2 and 2 to constitute a tire skeleton. Further, both end portions of the carcass layer 4 are folded and locked outward in the tire width direction so as to wrap the bead filler 3. The belt layer 5 includes a plurality of stacked belt plies 51 and 52, and is disposed on the outer periphery in the tire radial direction of the carcass layer 4. The tread rubber 6 is disposed on the outer circumference in the tire radial direction of the carcass layer 4 and the belt layer 5 to constitute a tread portion of the tire. The sidewall rubber 7 is disposed outside the bead filler 3 and the carcass layer 4 in the tire width direction and constitutes a sidewall portion of the tire.

[Belt cover layer]
The pneumatic tire 1 includes a first belt cover layer 8 and a second belt cover layer 9 (see FIG. 1). The first belt cover layer 8 is disposed so as to cover at least the center portion (region including the tread portion center crown CL) on the outer side in the tire radial direction of the belt layer 5. The second belt cover layer 9 is disposed so as to cover an end portion of the belt layer 5 on the outer side in the tire radial direction. That is, the first belt cover layer 8 and the second belt cover layer 9 are disposed on the outer side in the tire radial direction of the belt layer 5 to reinforce the belt layer 5. The first belt cover layer 8 may be disposed so as to cover not only the central portion of the belt layer 5 but also the end portion of the belt layer 5 (see FIGS. 1 and 2). It may be arranged so as to protrude outward in the tire width direction from the portion (not shown). The first belt cover layer 8 is preferably arranged in a range of 50 [%] or more with respect to the maximum width Wb of the belt layer 5.

  Further, the second belt cover layer 9 has an elastic modulus higher than that of the first belt cover layer 8. Accordingly, at least the central portion of the belt layer 5 is covered with the first belt cover layer 8 having a low elastic modulus, and the end portion of the belt layer 5 is covered with the second belt cover layer 9 having a high elastic modulus.

  In addition, the second belt cover layer 9 is wound around the belt layer 5 in a range of 1 round or more and less than 2 rounds. Further, the second belt cover layer 9 is disposed so as to be wound around the belt layer 5 in an annular shape. Therefore, the second belt cover layer 9 is arranged such that when the belt layer 5 is wound around the belt layer 5, its end portion (end portion on the winding end side) 92 overlaps itself (double winding). Is done. For this reason, the winding state of the second belt cover layer 9 is different from, for example, a spiral winding state (a state in which the belt cover layer is wound while being displaced in the axial direction of the belt layer without overlapping itself).

  For example, in this embodiment, the first belt cover layer 8 and the second belt cover layer 9 are disposed on the outer side in the tire radial direction of the belt layer 5 (see FIGS. 1 to 3). These belt cover layers 8 and 9 are made of a strip material obtained by rubberizing a plurality of cord materials. Further, the first belt cover layer 8 is disposed over substantially the entire region (including the central portion and the end portion) of the belt layer 5. Moreover, the 2nd belt cover layer 9 is each arrange | positioned with respect to the both ends of the tire width direction of the belt layer 5 (refer FIGS. 1-3).

  The elastic modulus of the second belt cover layer 9 is set to be higher than the elastic modulus of the first belt cover layer 8. Specifically, the first belt cover layer 8 is made of a low elastic modulus strip material (organic fiber cord), and the second belt cover layer 9 is made of a high elastic modulus strip material. Further, the elastic modulus of the first belt cover layer 8 and the elastic modulus of the second belt cover layer 9 are set to predetermined ranges, respectively.

  The first belt cover layer 8 is made of a single strip material (see FIG. 4). The strip material is continuously and spirally wound around the belt layer 5 in the tire circumferential direction, and is disposed from one end portion of the belt layer 5 to the other end portion. Moreover, the 2nd belt cover layer 9 is each wound around the both ends of the 1st belt cover layer 8, and is arrange | positioned (refer FIG. 4 and FIG. 5). Further, the second belt cover layer 9 is wound around the belt layer 5 (an end portion of the first belt cover layer 8) so as to be parallel to the tire circumferential direction (at an inclination angle of approximately 0 [deg]). ing. In addition, the second belt cover layer 9 is wound around the belt layer 5 in a range of 1 round or more and less than 2 rounds. Specifically, the second belt cover layer 9 has an annular structure by overlapping and winding the start end portion 91 and the end end portion 92 (see FIG. 6).

  In this embodiment, the start end portion 91 and the end end portion 92 of the second belt cover layer 9 are arranged so as to be completely coincided with each other in width (see FIG. 6). Instead, they may be arranged slightly shifted in the width direction (see FIG. 7). However, the start end portion 91 and the end end portion 92 of the second belt cover layer 9 need to be arranged so as to overlap at least partially. Thereby, the annular structure of the second belt cover layer 9 is secured.

[Tire manufacturing process]
In the manufacturing process of the pneumatic tire 1, each of the bead wire constituting the bead core 2, the carcass ply constituting the carcass layer 4, the belt plies 51 and 52 constituting the belt layer 5, the tread rubber 6, the sidewall rubber 7, etc. The member is put on a molding machine to mold a green tire (raw tire) (not shown). Next, this green tire is filled in a tire vulcanization mold. Next, the vulcanization mold is heated, and the green tire is expanded radially outward by a pressurizing device (vulcanization prada) and comes into contact with a tire molding die (tread surface molding portion) of the tire vulcanization mold. Next, when the green tire is heated, rubber molecules and sulfur molecules in the tread portion are bonded to each other and vulcanization is performed. At this time, the shape of the tire molding die is transferred to the tread surface of the green tire, and the tread pattern of the pneumatic tire 1 is molded. Then, the molded pneumatic tire is pulled out from the tire vulcanization mold.

  Here, in the vulcanization process of the green tire described above, it is preferable that the green tire is appropriately expanded by a vulcanization prada and pressed against a tire molding die. In this respect, in the pneumatic tire 1, the second belt cover layer 9 is wound around the end of the belt layer 5 so as to be wound in a range of 1 round or more and less than 2 rounds. As compared with a configuration (not shown) in which the belt is wound continuously and continuously (jointless), the binding force on the end of the belt layer 5 by the second belt cover layer 9 is reduced. For this reason, when a tensile force acts on the second belt cover layer 9 when the diameter of the green tire is increased, the start end portion 91 and the end end portion 92 of the second belt cover layer 9 are in the tire circumferential direction (in the direction of increasing the lap width t). Displacement causes the end of the belt layer 5 to lift following the deformation of the tire. As a result, (1) the thickness of the coating rubber between the second belt cover layer 9 and the belt layer 5 is properly secured, and the separation of the tread rubber 6 at the end of the belt layer 5 is reduced. Further, (2) since the contact between the tread rubber 6 and the tire molding die is appropriately ensured, the vulcanization failure of the tire is reduced.

[effect]
As described above, in the pneumatic tire 1, the second belt cover layer 9 is wound around the end of the belt layer 5 so as to be wound in a range of 1 round or more and less than 2 rounds. Compared with a configuration in which the layers are continuously wound around a plurality of times (not shown), the binding force at the end of the belt layer 5 by the second belt cover layer 9 is reduced. Then, when the diameter of the green tire expands during tire vulcanization, the start end portion 91 and the end end portion 92 of the second belt cover layer 9 can be displaced in the tire circumferential direction, so that the second belt cover layer 9 and the belt layer 5 The thickness of the coating rubber in between is ensured properly. Thereby, the separation of the tread rubber 6 at the end of the belt layer 5 is effectively reduced, and there is an advantage that the durability performance of the tire is improved.

  In the pneumatic tire 1, the second belt cover layer 9 is arranged around the belt layer 5 in an annular shape (the start end portion 91 and the end end portion 92 of the second belt cover layer 9 are overlapped). Therefore, the belt angle of the second belt cover layer 9 is also affected when the tire grows in diameter and the start end portion 91 and the end end portion 92 of the second belt cover layer 9 are displaced during vulcanization of the tire. hard. Thereby, there exists an advantage by which the uniformity of a tire is maintained appropriately. For example, in a configuration in which the second belt cover layer is spirally wound with a pitch in the width direction of the belt layer (the start and end portions of the second belt cover layer are not overlapped), the tire is When the start and end portions of the second belt cover layer are displaced during the vulcanization, the belt layer 5 is pulled by the second belt cover layer 9 and the belt angle of the belt ply 52 is disturbed. As a result, the uniformity of the tire may be deteriorated.

  In the pneumatic tire 1, the first belt cover layer 8 having a low elastic modulus is disposed at the center of the belt layer 5, and the second belt cover layer 9 having a high elastic modulus is provided at the end of the belt layer 5. By being arranged, secondary deformation of the diamond section is suppressed. Thereby, there exists an advantage by which the road noise of a mid range frequency (200 [Hz]-400 [Hz]) is reduced effectively. Even when the second belt cover layer 9 having a high elastic modulus is disposed only at the end of the belt layer 5, road noise is reduced. Further, when the belt cover layer having a high elastic modulus is disposed over the entire belt layer, the rigidity of the tread portion is excessively increased, and the riding comfort performance of the tire is deteriorated.

[Additional matter 1]
In this pneumatic tire 1, the lap width t between the start end portion 91 and the end end portion 92 of the second belt cover layer 9 is set to the circumferential length T of the second belt cover layer 9 in an unvulcanized state of the tire. It is preferable to have a relationship of 0.003 ≦ t / T (see FIG. 6). In such a configuration, since the lap width t of the second belt cover layer 9 is optimized, there is an advantage that the high-speed durability performance and uniformity of the tire are appropriately maintained. For example, when t / T <0.003, there is a possibility that a gap may be formed between the start end portion 91 and the end end portion 92 of the second belt cover layer 9 when the diameter of the green tire is expanded during tire vulcanization. Then, the rigidity of the tread portion becomes uneven in the tire circumferential direction, and there is a possibility that the high-speed durability performance and uniformity of the tire are deteriorated.

  For example, in this embodiment, the circumferential length T of the second belt cover layer 9 is T = 2000 [mm] in the unvulcanized state of the tire. On the other hand, the lap width t between the start end 91 and the end end 92 of the second belt cover layer 9 is set to t = 60 [mm]. When the tire is vulcanized, the end portion 92 of the second belt cover layer 9 is displaced by 30 [mm] to 40 [mm] (the wrap width t is reduced) due to the tire diameter growth. With this configuration, the lap width t of the second belt cover layer 9 is ensured appropriately.

  Further, in this pneumatic tire 1, in the product tire, the lap width t between the start end portion 91 and the end end portion 92 of the second belt cover layer 9 is t / T with respect to the circumferential length T of the second belt cover layer 9. It is preferable to have a relationship of ≦ 0.50 (see FIG. 6). In such a configuration, since the binding force of the end of the belt layer by the second belt cover layer is optimized, the thickness of the coating rubber between the second belt cover layer and the belt layer in the tire vulcanization process is increased. Thickness is secured. Thereby, there exists an advantage by which the separation of the tread rubber 6 in the edge part of the belt layer 5 is reduced effectively. For example, when 0.50 <t / T, the binding force of the end portion of the belt layer by the second belt cover layer becomes excessive, and is between the second belt cover layer and the belt layer in the vulcanization process of the tire. It becomes difficult to secure the thickness of the coating rubber. Then, the separation of the tread rubber is likely to occur at the end portion of the belt layer.

[Additional matter 2]
Moreover, in this pneumatic tire 1, it is preferable that the 1st belt cover layer 8 has a jointless structure (refer FIG. 4). Thereby, there is an advantage that the splice component is reduced and the uniformity of the tire is improved.

  For example, in this embodiment, the first belt cover layer 8 is made of a single strip material, and this strip material is arranged continuously and spirally in the tire circumferential direction (see FIG. 4). Thereby, the first belt cover layer 8 having a jointless structure is formed.

[Additional matter 3]
In the pneumatic tire 1, the first belt cover layer 8 is disposed outside the belt layer 5 in the tire radial direction, and the second belt cover layer 9 is disposed outside the first belt cover layer 8. Preferred (see FIGS. 2 and 3). That is, the first belt cover layer 8 having a low elastic modulus is interposed between the belt layer 5 and the second belt cover layer 9 having a high elastic modulus.

  In such a configuration, since the second belt cover layer 9 has a high elastic modulus and is wound around the belt layer 5 in a range of 1 round or more and less than 2 rounds, when the tire diameter grows during vulcanization of the tire, The second belt cover layer 9 is greatly displaced in the tire circumferential direction. On the other hand, the first belt cover layer 8 having a low elastic modulus extends more greatly when the tire diameter grows during vulcanization of the tire, and thus its position is difficult to be displaced. Therefore, when the first belt cover layer 8 is sandwiched between the belt layer 5 and the second belt cover layer 9, the belt angle of the belt layer 5 is changed by the displacement of the second belt cover layer 9 during vulcanization of the tire. The impact is reduced. Thereby, there exists an advantage by which the uniformity of a tire is maintained appropriately.

[Additional matter 4]
Moreover, in this pneumatic tire 1, the 2nd belt cover layer 9 is each arrange | positioned at the both ends of the tire width direction of the 1st belt cover layer 8 (refer FIG. 4 and FIG. 5). Further, the position of the end portion of the first belt cover layer 8 and the position of the end portion of the second belt cover layer 9 are aligned.

  However, the present invention is not limited to this, and the position of the end portion of the first belt cover layer 8 and the position of the end portion of the second belt cover layer 9 may be shifted in the tire width direction. For example, the end portion of the second belt cover layer 9 may be positioned on the inner side in the tire width direction than the end portion of the first belt cover layer 8 (see FIGS. 8 and 9), and conversely, the second belt The end portion of the cover layer 9 may be located on the outer side in the tire width direction than the end portion of the first belt cover layer 8 (not shown).

  A plurality of second belt cover layers 9, 9 may be disposed at both ends of the first belt cover layer 8 (see FIGS. 10 and 11). For example, a pair of second belt cover layers 9 and 9 are disposed at each end of the first belt cover layer 8. At this time, the second belt cover layers 9, 9 are independent of each other.

  Moreover, the 1st belt cover layer 8 and the 2nd belt cover layer 9 may be arrange | positioned in parallel (refer FIG. 12 and FIG. 13). For example, the first belt cover layer 8 is disposed only at the center of the belt layer 5, and the second belt cover layer 9 is disposed only at both ends of the belt layer 5. Further, the first belt cover layer 8 and the second belt cover layer 9 are arranged in parallel without being laminated.

  Further, the second belt cover layer 9 may be disposed inside the first belt cover layer 8 in the tire radial direction (see FIGS. 14 and 15). For example, the second belt cover layer 9 is disposed on both ends of the belt layer 5, and the first belt cover layer 8 is disposed so as to cover the second belt cover layers 9 and 9 and the belt layer 5.

[Additional matter 5]
Further, in this pneumatic tire 1, the stretch rate of 2.0 [cN / dtex] of the belt cover material constituting the first belt cover layer 8 is in the range of 4.0 [%] to less than 10.0 [%]. And the elongation ratio of 2.0 [cN / dtex] of the belt cover material constituting the second belt cover layer 9 is in the range of 1.5 [%] or more and less than 4.0 [%]. It is preferable. In such a configuration, since the elastic modulus of the first belt cover layer 8 and the second belt cover layer 9 is optimized, road noise at the mid-frequency (200 [Hz] to 400 [Hz]) is effectively reduced. There are advantages.

  In the pneumatic tire 1, the belt cover material of the first belt cover layer 8 is made of nylon fiber, and the belt cover material of the second belt cover layer 9 is polyester fiber, polyketone fiber, lyocell fiber, aramid fiber, It is preferably made of a composite fiber formed by twisting an aramid fiber and a nylon fiber, or a composite fiber formed by twisting a polyketone fiber and a nylon fiber. In such a configuration, since the material (elastic modulus) of the first belt cover layer 8 and the second belt cover layer 9 is optimized, road noise at a mid-frequency (200 [Hz] to 400 [Hz]) is effective. Has the advantage of being reduced.

  In the pneumatic tire 1, the belt layer 5 is preferably made of steel belt plies 51 and 52 (see FIGS. 1 and 2). In such a configuration, the rigidity of the belt layer 5 is increased as compared with a configuration in which the belt layer is made of a belt ply made of organic fibers. Thereby, there exists an advantage which the high-speed durability performance of a tire improves. In this embodiment, the pair of belt plies 51 and 52 are laminated with their fiber directions crossed to increase the strength of the belt layer 5 (cross-ply structure).

[Additional matter 6]
In the pneumatic tire 1, the maximum width Wb of the belt layer 5 and the total width Wc of the second belt cover layer 9 disposed at one end of the belt layer 5 are 0.02 ≦ Wc / Wb ≦ It is preferable to have a relationship of 0.35 (see FIG. 3). More preferably, the maximum width Wb and the total width Wc have a relationship of 0.05 ≦ Wc / Wb ≦ 0.30.

  In such a configuration, since the ratio Wc / Wb between the maximum width Wb of the belt layer 5 and the total width Wc of the second belt cover layer 9 is optimized, there is an advantage that road noise at the mid frequency is effectively reduced. is there. Moreover, there is an advantage that the riding comfort performance of the tire is maintained appropriately. For example, when Wc / Wb <0.02, a road noise reduction effect cannot be obtained sufficiently. Further, when 0.35 <Wc / Wb, the effect of reducing road noise is difficult to increase, and the rigidity of the second belt cover layer is excessive, which may deteriorate the riding performance of the tire.

  In the configuration in which the plurality of second belt cover layers 9 are disposed at one end of the belt layer 5 (see FIGS. 10 and 11), the sum of the widths of the second belt cover layers 9 is the second belt. The total width Wc of the cover layer 9 is obtained.

  Further, in the pneumatic tire 1, the distance Xb from the tread center crown CL to the maximum width position of the belt layer 5 and the tread portion center crown CL to the outer end in the tire width direction of the second belt cover layer 9. The distance Xc preferably has a relationship of 0.70 ≦ Xb / Xc ≦ 1.20 (see FIG. 3). More preferably, the distance Xb and the distance Xc have a relationship of 0.80 ≦ Xb / Xc ≦ 1.10.

  In such a configuration, since the positional relationship between the end of the belt layer 5 and the second belt cover layer 9 is optimized, there is an advantage that road noise at the mid-frequency is effectively reduced, and the tire uniformity is also improved. There is an advantage that is maintained. For example, when Xb / Xc <0.70, the effect of reducing road noise cannot be obtained sufficiently. When 1.20 <Xb / Xc, the second belt cover layer protrudes excessively beyond the end of the belt layer, and the belt cover layer protruding from the belt layer during shaping of the green tire is lifted. Disappear. As a result, the shoulder portion of the finished green tire is likely to have a wavy shape in the tire circumferential direction, and the uniformity of the tire may be deteriorated.

[performance test]
In this example, performance tests on (1) road noise resistance, (2) high-speed durability, (3) riding comfort, and (4) vibration resistance were performed on a plurality of pneumatic tires with different conditions. (See FIGS. 16 to 19). In this performance test, a pneumatic tire having a tire size of 215 / 55R17 is assembled to a rim having a rim size of 17 × 7 JJ, and an internal pressure of 200 [kPa] and a regular load specified by JATMA are applied to the pneumatic tire. The pneumatic tire is mounted on a domestic FR vehicle with a displacement of 2500 [cc].

  (1) In the performance test related to road noise resistance, a test vehicle equipped with pneumatic tires travels on a test course having a rough road surface at 60 [km / h], and sounds are generated by a microphone attached to the center position of the test vehicle. The pressure level is measured. And based on this measurement result, the evaluation which used the pneumatic tire of the prior art example as a standard (0) is performed. The evaluation result is preferably as the numerical value is smaller (negative) as the sound pressure level is lower.

  (2) In the performance test relating to the high-speed durability performance, a drum having a drum diameter of 1707 mm is used, and an indoor high-speed durability test in accordance with JIS-D4230 is performed. Thereafter, the drum rotation speed is increased by 10 km / h every 30 minutes, and the drum rotation speed when the pneumatic tire is damaged is measured. Then, based on the measurement result, index evaluation is performed using the conventional pneumatic tire 1 as a reference (100). An evaluation result is so preferable that the numerical value is large.

  (3) In the performance test related to riding comfort performance, a test vehicle equipped with pneumatic tires travels on a dry road evaluation course, and a specialized test driver performs sensory evaluation. This evaluation is performed by index evaluation using the pneumatic tire of Conventional Example 2 as a reference (100), and the larger the value, the better.

  (4) In the performance test related to vibration resistance performance, a test vehicle equipped with pneumatic tires runs on an evaluation course on a dry road surface, and a specialized test driver performs sensory evaluation. This evaluation is performed by index evaluation using the pneumatic tire of Conventional Example 2 as a reference (100), and the larger the value, the better.

  In the conventional pneumatic tire, the first belt cover layer and the second belt cover layer are both made of a belt cover material made of nylon fiber, and have a low elastic modulus (elongation rate 7.0 [%]). In addition, the second belt cover layer is continuously wound around the end of the belt layer in a spiral manner. The number of turns of the second belt cover layer is three.

  In the pneumatic tires 1 of Invention Examples 1 to 10, the first belt cover layer 8 is made of a belt cover material made of nylon fiber (elongation rate 7.0 [%]), and the second belt cover layer 9 is made of polyketone fiber ( The belt cover material is composed of an elongation rate of 2.0 [%] (see FIGS. 1 to 6). For this reason, the elastic modulus of the second belt cover layer 9 is set higher than the elastic modulus of the first belt cover layer 8. Further, the second belt cover layer 9 is disposed so as to be annularly wound with respect to both end portions of the belt layer 5 within a range of 1 round or more and less than 2 rounds.

  As shown in the test results, it can be seen that road noise is reduced in the pneumatic tires 1 of Invention Examples 1 to 3 (see FIG. 16). It can also be seen that the high-speed durability performance of the tire is more suitably maintained by optimizing the ratio t / L between the lap width t and the circumferential length L of the second belt cover layer 9. The high-speed durability performance of the tire is considered to be sufficiently maintained when the index value based on the conventional example is −15 or more.

  Further, when the conventional example and the invention example 4 are compared, the road belt noise is appropriately reduced by setting the elastic modulus of the second belt cover layer 9 higher than the elastic modulus of the first belt cover layer 8, and It can be seen that the riding performance of the tire is maintained (see FIG. 17).

  Further, when comparing the conventional example with Invention Examples 4 to 6, the width Wc of the second belt cover layer 9 is optimized, so that the road noise of the tire is appropriately reduced, and the riding comfort performance of the tire is improved. It can be seen that the suitability is maintained (see FIG. 18).

  In addition, when Invention Examples 8 to 10 are compared, the installation position of the second belt cover layer 9 with respect to the end of the belt layer 5 is optimized, so that the road noise of the tire is appropriately reduced, and the tire resistance is reduced. It can be seen that the vibration performance is maintained appropriately (see FIG. 19).

As described above, the pneumatic tire and the method for manufacturing a pneumatic tire according to the present invention are useful in that the durability performance of the tire can be improved.

It is sectional drawing of the tire meridian direction which shows the pneumatic tire concerning the Example of this invention. It is explanatory drawing which shows the belt cover layer of the pneumatic tire described in FIG. It is explanatory drawing which shows the belt cover layer of the pneumatic tire described in FIG. It is explanatory drawing which shows the belt cover layer of the pneumatic tire described in FIG. It is explanatory drawing which shows the belt cover layer of the pneumatic tire described in FIG. It is explanatory drawing which shows the belt cover layer of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is explanatory drawing which shows the modification of the belt cover layer described in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead core 3 Bead filler 4 Carcass layer 5 Belt layer 51 Belt ply 52 Belt ply 6 Tread rubber 7 Side wall rubber 8 First belt cover layer 9 Second belt cover layer 91 Start end part 92 End part

Claims (11)

A belt layer disposed on the outer side in the tire radial direction of the carcass layer, a first belt cover layer disposed to cover at least a central portion on the outer side in the tire radial direction of the belt layer, and an end on the outer side in the tire radial direction of the belt layer A pneumatic tire having a second belt cover layer disposed over the portion,
The second belt cover layer has an elastic modulus higher than the elastic modulus of the first belt cover layer, and is disposed so as to be annularly wound around the belt layer in a range of 1 round or more and less than 2 rounds. And pneumatic tires.   In the unvulcanized state of the tire, the lap width t between the start end portion and the end end portion of the second belt cover layer has a relationship of 0.003 ≦ t / T with respect to the circumferential length T of the second belt cover layer. The pneumatic tire according to claim 1.   The product tire has a relationship in which a lap width t between a starting end portion and a terminal end portion of the second belt cover layer has a relationship of t / T ≦ 0.50 with respect to a circumferential length T of the second belt cover layer. Or the pneumatic tire of 2.   The pneumatic tire according to claim 1, wherein the first belt cover layer has a jointless structure.   The first belt cover layer is disposed outside the belt layer in the tire radial direction, and the second belt cover layer is disposed outside the first belt cover layer. Pneumatic tires.   The belt cover material constituting the first belt cover layer has an elongation rate of 2.0 [cN / dtex] in the range of 4.0 [%] to less than 10.0 [%], and the second The belt cover material constituting the belt cover layer has an elongation rate of 2.0 [cN / dtex] in the range of 1.5 [%] or more and less than 4.0 [%]. Pneumatic tire described in one.   The belt cover material of the first belt cover layer is made of nylon fiber, and the belt cover material of the second belt cover layer is formed by twisting polyester fiber, polyketone fiber, lyocell fiber, aramid fiber, aramid fiber and nylon fiber. The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire is formed of a composite fiber formed by twisting a polyketone fiber and a nylon fiber.   The pneumatic tire according to any one of claims 1 to 7, wherein the belt layer is made of a steel belt ply.   The maximum width Wb of the belt layer and the total width Wc of the second belt cover layer disposed at one end of the belt layer have a relationship of 0.02 ≦ Wc / Wb ≦ 0.35. The pneumatic tire according to any one of 1 to 8.   A distance Xb from the tread portion center crown CL to the maximum width position of the belt layer and a distance Xc from the tread portion center crown CL to the outer end portion in the tire width direction of the second belt cover layer are 0.70 ≦ Xb. The pneumatic tire according to claim 1, having a relationship of /Xc≦1.20. A belt layer disposed on the outer side in the tire radial direction of the carcass layer, a first belt cover layer disposed to cover at least a central portion on the outer side in the tire radial direction of the belt layer, and an end on the outer side in the tire radial direction of the belt layer A method for manufacturing a pneumatic tire having a second belt cover layer disposed over a portion,
The second belt cover layer has an elastic modulus higher than the elastic modulus of the first belt cover layer, and is arranged in a ring shape in a range of not less than 1 and less than 2 with respect to the belt layer, A method for manufacturing a pneumatic tire, comprising: displacing a starting end portion and a terminal end portion of the second belt cover layer in a tire circumferential direction when the diameter of the green tire is expanded during tire vulcanization.

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