JP2007015638A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively suppress separation at an outer end in the width direction of a belt ply 25 of the maximum width. <P>SOLUTION: A reinforcement cord 26 inside the belt ply 25 of the maximum width comprises a normal diameter reinforcement cord 26a and a small diameter reinforcement cord 26b arranged alternately with the normal diameter reinforcement cord 26a and having diameter smaller than that of the normal diameter reinforcement cord 26a. Since both outer end parts of the small diameter reinforcement cord 26b are protruded outwardly from both outer ends 42 of the normal diameter reinforcement cord 26a, distortion is generated between the outer ends 42 of the normal diameter reinforcement cord 26a and its surrounding rubber and between the outer ends 43 of the small diameter reinforcement cord 26b and its surrounding rubber. As a result, distortion is dispersed and separation can be effectively suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to a pneumatic tire in which a belt reinforcing layer in which reinforcing elements extending in the circumferential direction are embedded is disposed between a carcass layer and a belt layer.

In the past, the present applicant, in a pneumatic tire having an aspect ratio of 0.70 or less, an invention that can effectively suppress interlayer separation between the belt layer at the outer end portion in the width direction of the belt reinforcing layer, Proposed in US Pat.
JP 2003-154808 A

  This includes at least one carcass layer extending in a toroidal shape between a pair of beads and a reinforcing cord that is disposed radially outside the carcass layer and is inclined with respect to the tire equator S inside. A belt layer made of a belt ply, a belt reinforcing layer made of at least one reinforcing ply disposed between the carcass layer and the belt layer and having a reinforcing element extending substantially in the circumferential direction embedded therein, and the belt A tread disposed radially outward of the layer, and the width of the widest reinforced ply, which is the widest of the reinforced plies, is at least 0.6 times the width of the tire and one widest widest Only the belt ply is wider than the widest reinforcing ply.

  Similarly, the present applicant has proposed in Japanese Patent Application No. 2005-15019 an invention that can effectively suppress the separation between the belt layer and the belt reinforcing layer in a pneumatic tire having an aspect ratio of 0.70 or less.

  This includes at least one carcass layer extending in a toroidal shape between a pair of bead cores and a reinforcing cord that is disposed radially outside the carcass layer and is inclined with respect to the tire equator S inside. A belt layer made of a belt ply, a belt reinforcing layer made of at least one reinforcing ply disposed between the carcass layer and the belt layer and having a reinforcing element extending substantially in the circumferential direction embedded therein, and the belt A pneumatic tire in which the width of the widest reinforcing ply which is the widest width is 0.6 times or more of the tire width. The belt layer overlaps with the outer end portion in the width direction of the belt layer, and the inner end in the width direction is located on the inner side in the width direction with respect to the outer end in the width direction of the widest reinforcing ply. A pair of split belt layers in which inclined reinforcement cords are embedded are provided.

    As a result, the interlayer separation between the belt reinforcing layer and the belt layer at the outer end in the width direction can be suppressed to a considerable extent. A problem has arisen that separation occurs at the outer edge in the width direction of the belt layer.

  For this reason, the present inventor conducted earnest research on the separation at the outer end in the width direction of the widest belt ply or the divided belt layer described above, and obtained the following knowledge. That is, since the tread portion in the grounding region is deformed from an arc shape to a flat shape at the time of grounding, the belt layer and the divided belt layer in the tread portion are deformed so as to extend in the circumferential direction, and the belt layer and the divided belt layer The reinforcement cord of the tire is inclined so as to approach the tire equator (the inclination angle becomes smaller). As a result, a large distortion occurs between the reinforcing cord and the surrounding rubber at the outer end in the width direction of the widest belt ply or the split belt layer, and such distortion is repeatedly generated by the rotation of the pneumatic tire. A crack occurs in the above-mentioned part, and such a crack progresses to cause separation.

  The present invention has been made on the basis of the above-mentioned knowledge, and the invention according to claim 1 is arranged in a toroidal shape between a pair of bead cores, disposed radially outside the carcass layer, and has a tire equator inside. A belt layer composed of at least one belt ply in which a large number of reinforcing cords inclined with respect to S are embedded, and is disposed between the carcass layer and the belt layer, and extends substantially circumferentially inside. A belt reinforcing layer comprising at least one reinforcing ply in which a reinforcing element is embedded; and a tread disposed radially outward of the belt layer, wherein the widest reinforcing ply of the widest width is the widest of the reinforcing plies. In a pneumatic tire in which the width L is 0.6 times or more the tire width W and the widest belt ply, which is the widest width, is wider than the widest reinforcing ply, the widest belt The reinforcing cord embedded in the rut ply is composed of a normal diameter reinforcing cord and a small diameter reinforcing cord having a smaller diameter than the normal diameter reinforcing cord and alternately arranged with the normal diameter reinforcing cord. Both outer ends are projected outward from both outer ends of the normal diameter reinforcing cord,

  The invention according to claim 2 includes a carcass layer extending in a toroidal shape between a pair of bead cores, and a plurality of reinforcing cords disposed radially outside the carcass layer and inclined with respect to the tire equator S inside. A belt layer composed of at least one belt ply embedded, and at least one reinforcement ply disposed between the carcass layer and the belt layer and having a reinforcement element extending substantially in the circumferential direction therein. A pneumatic reinforcement having a belt reinforcing layer and a tread disposed radially outward of the belt layer, wherein the width L of the widest reinforcing ply, which is the widest width of the reinforcing plies, is at least 0.6 times the tire width W In the tire, the inner end in the width direction overlaps the outer end in the width direction of the widest belt ply, and the inner end in the width direction is positioned inward in the width direction from the outer end in the width direction of the widest reinforcing ply. A pair of split belt layers embedded with reinforcement cords that are inclined with respect to the tire equator S, and the reinforcement cords embedded in the split belt layers are defined as normal diameter reinforcement cords The small-diameter reinforcing cords are smaller than the normal-diameter reinforcing cords and are arranged alternately with the normal-diameter reinforcing cords, and the outer ends of the small-diameter reinforcing cords protrude outward from the outer ends of the normal-diameter reinforcing cords. Is.

  In the invention according to claim 1, among the belt ply and the reinforcing ply, the reinforcing cord embedded in the widest belt ply which is the widest width is a normal diameter reinforcing cord having the same diameter as a conventional reinforcing cord, It is composed of normal diameter reinforcing cords and small diameter reinforcing cords arranged alternately, and both outer ends of the small diameter reinforcing cords protrude outward from both outer ends of the normal diameter reinforcing cords. Sometimes when the widest belt ply stretches and deforms in the circumferential direction, and when the normal diameter reinforcing cord and the small diameter reinforcing cord are inclined so as to approach the tire equator, the outer ends of the normal diameter reinforcing cord and the surrounding rubber Distortion occurs between both the outer ends of the small-diameter reinforcing cord and the surrounding rubber, and the strain is dispersed, so that separation is effectively suppressed.

  At this time, since both outer ends of the small-diameter reinforcing cord protrude outward from both outer ends of the normal-diameter reinforcing cord, large distortion occurs between both outer ends of the small-diameter reinforcing cord and the surrounding rubber. However, these small-diameter reinforcing cords are smaller in number than the conventional reinforcing cords embedded in the widest belt ply, and are smaller in diameter than the normal-diameter reinforcing cords and less in bending rigidity. The deformation easily follows the extension, and as a result, the strain between the outer ends of the small-diameter reinforcing cord and the rubber around it is suppressed to a relatively small value, and the occurrence of separation at the portion is effectively suppressed. .

  In the invention according to claim 2, the reinforcing cord embedded in the split belt layer whose outer end in the width direction is positioned on the outer side in the width direction from the outer end in the width direction of the widest belt ply and the widest reinforcing ply. A normal diameter reinforcing cord having the same diameter as that of the conventional reinforcing cord, and a small diameter reinforcing cord arranged alternately with the normal diameter reinforcing cord, and an outer end of the small diameter reinforcing cord being an outer end of the normal diameter reinforcing cord. Since it protrudes further outward, it is between the outer end of the normal diameter reinforcing cord and the surrounding rubber, and between the outer end of the small diameter reinforcing cord and the surrounding rubber, as in the invention according to claim 1. While distortion occurs in both of them, the distortion is dispersed and separation is effectively suppressed, while the distortion between the outer end of the small-diameter reinforcing cord and the surrounding rubber is suppressed to a relatively small value. Separation in Occurrence of is effectively suppressed.

According to the third aspect of the present invention, the separation at the outermost ends of the widest belt ply and the split belt layer is effectively suppressed while sufficiently ensuring the shear rigidity of the belt layer and the split belt layer. be able to.
Furthermore, if comprised as described in Claim 4, the separation in the outer end of the widest belt ply and a division | segmentation belt layer can be suppressed effectively, preventing a weight increase.

Further, when configured as described in claim 5, it is possible to sufficiently secure the shear rigidity that is the original purpose of the belt layer while reducing the difference in the circumferential extension amount between the belt layer and the belt reinforcing layer. it can.
Further, according to the sixth and seventh aspects, the widest belt ply in which the normal diameter reinforcing cord and the small diameter reinforcing cord are alternately arranged while preventing the contact between the normal diameter reinforcing cord and the small diameter reinforcing cord. The split belt layer can be easily formed.

Further, if configured as described in claim 8, the distance in the thickness direction between the normal diameter reinforcing cord and the small diameter reinforcing cord can be easily reduced, whereby the thickness of the widest belt ply and the split belt layer can be reduced. Meat can be effectively suppressed.
Furthermore, if comprised as described in Claim 9, both shear rigidity and cut resistance can be improved.

According to the tenth aspect, interlayer separation between the belt reinforcing layer and the belt layer at the outer end in the width direction can be more effectively suppressed.
Furthermore, if comprised as described in Claim 11, since a reinforcement element expand | extends in the circumferential direction at the time of vulcanization, manufacture of a pneumatic tire becomes easy.

Embodiment 1 of the present invention will be described below with reference to the drawings.
In FIGS. 1 and 2, reference numeral 11 denotes a heavy-duty pneumatic radial tire having a flatness ratio of 0.70 or less that is mounted on a truck or bus. The pneumatic tire 11 has a pair of bead portions 12. The bead cores 13 that are paired (here, a pair but may be a plurality of pairs) are embedded. Further, the pneumatic tire 11 includes a sidewall portion 14 extending substantially radially outward from the bead portion 12, and a substantially cylindrical tread portion 15 that connects the radially outer ends of both sidewall portions 14. And further.

  The pneumatic tire 11 has a carcass layer 18 that extends between the bead cores 13 in a toroidal manner and reinforces the sidewall portions 14 and the tread portions 15. Both end portions of the carcass layer 18 surround the bead cores 13. It is folded from the inside to the outside. The carcass layer 18 is composed of at least one, in this case, one carcass ply 19, and the carcass ply 19 has a non-stretchable reinforcing cord 20, such as a steel cord, extending substantially in the radial direction (meridian direction). There are many buried. Further, a chafer 21 reinforced with, for example, a steel cord is disposed around the carcass layer 18 in the bead portion 12.

  A belt layer 24 is arranged on the outer side in the radial direction of the carcass layer 18 and is slightly wider than the tread width H. The belt layer 24 is composed of at least one (here, one) belt ply 25. A large number of non-stretchable reinforcing cords 26 made of, for example, steel or aromatic polyamide are embedded in the belt ply 25. Here, since the belt layer 24 is composed of one belt ply 25 as described above, the belt ply 25 becomes the widest belt ply.

  Here, the reinforcing cord 26 embedded in the belt ply 25 reduces the difference in the amount of circumferential extension between the belt ply 25 and the width direction outer end of the belt reinforcing layer, which will be described later. In order to effectively suppress separation, the tire equator S is preferably inclined at an inclination angle A of 40 degrees or more. However, if the inclination angle A exceeds 70 degrees, the shearing rigidity, which is the original purpose of the belt layer 24, cannot be sufficiently ensured (performance such as wear is sufficiently ensured). It is preferable to make it below the degree. Thus, the inclination angle A is preferably within a range of 40 to 70 degrees in any belt ply 25. Reference numeral 28 denotes a tread disposed radially outside the carcass layer 18 and the belt layer 24.

  31 is a belt reinforcing layer disposed radially inward of the belt layer 24, more specifically, between the carcass layer 18 and the belt layer 24 so as to overlap the belt layer 24. At least one belt reinforcing layer 31 is provided. Here, it is composed of two reinforced plies 32 and 33 laminated. Reinforcing elements 34 and 35 made of a non-extensible material such as steel and aromatic polyamide are embedded in the reinforcing plies 32 and 33 substantially in the circumferential direction, and these reinforcing elements 34 and 35 are cords. (Strand wires) or monofilaments, and a large number of them appear on the meridional section of each reinforcing ply 32, 33.

  Here, the reinforcing elements 34 and 35 are bent in a wave shape or a zigzag shape, and as a result, the reinforcing elements 34 and 35 extend in the circumferential direction during vulcanization, thereby facilitating the manufacture of the pneumatic tire 11. Can do. The reinforcing elements 34 and 35 may extend linearly in the circumferential direction. In this case, a cord having a large initial elongation is used in order to ensure expansion during manufacturing (vulcanization).

  Here, each of the reinforcing plies 32 and 33 can be configured by, for example, winding a strip of rubber covering one or a small number of reinforcing elements 34 and 35 around the outer side of the carcass layer 18 in a spiral manner. Also, among the reinforced plies 32 and 33, the widest reinforced ply which is the widest width (here, both the inner and outer reinforced plies 32 and 33 are equal in width, so both the reinforced plies 32 and 33 are the widest reinforced ply. ) Is narrower than the width P of the widest belt ply 25, and conversely, the widest belt ply 25 is wider than the widest reinforcing plies 32 and 33.

  Further, the width L of the widest reinforcing plies 32 and 33 described above is set to be 0.6 times or more the tire width W. Here, the reason why the width L of the reinforced plies 32 and 33, which is the widest width, is set to 0.6 times or more of the tire width W is that, as described above, in the pneumatic tire 11 having a flatness ratio of 0.70 or less, the diameter growth due to internal pressure filling is increased. This is to make it almost uniform.

  38 is an intermediate rubber layer interposed between the outer end portion in the width direction of the outer reinforcing ply 33 and the widest belt ply 25 adjacent to the outer end portion in the width direction. It is made of rubber having a lower JIS hardness. Then, if the intermediate rubber layer 38 is interposed at such a position, the rubber gauge between the outer end in the width direction of the outer reinforcing ply 33 and the widest belt ply 25 adjacent to the outer end in the width direction. As a result, the shear deformation between them can be reduced.

  Further, in this embodiment, apart from the rubber layer 38 described above, the lateral rubber layers 40 are disposed on the outer sides (left and right sides) in the width direction of the widest reinforcing plies 32 and 33, respectively. The outer end in the width direction of the layer 40 extends from the outer end in the width direction of the widest belt ply 25 to the outer side in the width direction.

  However, in the case of the pneumatic tire 11 having the above-described structure, the belt layer 24 in the ground contact region is deformed so as to extend in the circumferential direction at the time of ground contact, and the reinforcing cord 26 in the belt layer 24 is formed on the tire equator S. Inclined to approach (the inclination angle becomes smaller), and as a result, large distortion occurs between the reinforcing cord 26 and the surrounding rubber at both outer ends in the width direction of the widest belt ply 25. Since the distortion repeatedly occurs due to the rotation of the pneumatic tire 11, cracks may occur at both outer ends in the width direction of the widest belt ply 25, and such cracks may develop into separation.

  Therefore, in this embodiment, as shown in FIGS. 1, 2, and 3, the reinforcing cord 26 embedded in the widest belt ply 25 is replaced with a normal diameter reinforcing cord 26a having the same diameter as the conventional reinforcing cord. The reinforcing cords are composed of two types of reinforcing cords, ie, small-diameter reinforcing cords 26b which are smaller in diameter than the normal-diameter reinforcing cords 26a and are arranged alternately with the normal-diameter reinforcing cords 26a. 26b, and both outer ends in the longitudinal direction of the small-diameter reinforcing cord 26b protrude outward in the tire width direction from both outer ends 42 in the longitudinal direction of the normal-diameter reinforcing cord 26a.

  As a result, when the widest belt ply 25 is stretched and deformed in the circumferential direction at the time of grounding as described above, the normal diameter reinforcement cord 26a and the small diameter reinforcement cord 26b are inclined so as to approach the tire equator S. Distortion occurs between the outer end 42 of the cord 26a and the surrounding rubber and between the outer end 43 of the small-diameter reinforcing cord 26b and the surrounding rubber to disperse the distortion. Is effectively suppressed.

  At this time, since both outer end portions of the small-diameter reinforcing cord 26b protrude outward from both outer ends 42 of the normal-diameter reinforcing cord 26a, a large distortion is caused between the outer end 43 of the small-diameter reinforcing cord 26b and the surrounding rubber. However, these small-diameter reinforcing cords 26b are smaller in number than the conventional reinforcing cords embedded in the widest belt ply (the number of driven-in cords is half that of conventional ones), and the normal diameter Since it has a smaller diameter than the reinforcing cord 26a and has a small bending rigidity, it easily deforms following the circumferential extension described above.

  As a result, the distortion between the outer end 43 of the small-diameter reinforcing cord 26b and the surrounding rubber is suppressed to a relatively small value, and the occurrence of separation at the portion is effectively suppressed. In addition, since a part of the conventional reinforcing cord is replaced with the small-diameter reinforcing cord 26b as described above, the shear rigidity of the belt layer 24 is lowered. However, both outer ends of the small-diameter reinforcing cord 26b are connected to the normal-diameter reinforcing cord. Since the width is widened by projecting outward from both outer ends 42 of 26a, the reduction in the shear rigidity can be suppressed.

  Here, in this embodiment, the normal diameter reinforcing cords 26a and the small diameter reinforcing cords 26b are alternately arranged one by one. However, if necessary, the former is alternately arranged by two and the latter one by one. Two and the latter may be alternately arranged. The diameter D of the small-diameter reinforcing cord 26b described above is preferably in the range of 0.1 to 0.7 times the diameter E of the normal-diameter reinforcing cord 26a. The reason is that if the D / E value is less than 0.1, the shear rigidity of the belt layer 24 may not be sufficiently secured. On the other hand, if it exceeds 0.7, the outer end 43 of the small-diameter reinforcing cord 26b is separated. Although it may occur, separation within the outer end 43 of the small-diameter reinforcing cord 26b can be effectively suppressed while ensuring sufficient shear rigidity of the belt layer 24 within the aforementioned range. .

  Further, it is preferable that the projecting amount M outward in the width direction from the outer end 42 of the normal diameter reinforcing cord 26a to the outer end 43 of the small diameter reinforcing cord 26b is in the range of 5 to 25 mm. The reason is that if the value is less than 5 mm, the separation at the outer end of the widest belt ply 25 may not be effectively suppressed, while if it exceeds 25 mm, the separation suppressing effect is saturated and the weight is reduced. This is because the increase at the outer end of the widest belt ply 25 can be effectively suppressed while preventing an increase in weight, while the increase in weight is only caused.

  The widest belt ply 25 in which the normal diameter and small diameter reinforcing cords 26a and 26b as described above are alternately embedded is formed, for example, as follows. That is, first, a first ply segment 46 in which a normal diameter reinforcing cord 26a is repeatedly embedded in the intermediate tire before vulcanization, more specifically, radially outward of the belt reinforcing layer 31, and a small diameter reinforcing cord 26b. As shown in FIG. 4, the second ply segment 47 in which the small-diameter reinforcing cords 26b are embedded by the same number as that of the normal-diameter reinforcing cords 26a, as shown in FIG. Between the diameter reinforcing cords 26a, more specifically, the small diameter reinforcing cords 26b are arranged in close contact with each other, and the tread 28 made of unvulcanized rubber is provided radially outside the first and second ply segments 46, 47. To form an unvulcanized tire.

  Next, when the unvulcanized tire is carried into a vulcanizer and vulcanized, the first and second ply segments 46 and 47 are integrated. At this time, the first and second ply segments are integrated. The coating rubbers 48 and 49 of the segments 46 and 47 flow by the vulcanization pressure, and the small diameter reinforcing cord 26b enters the first ply segment 46 (coating rubber 48) between the normal diameter reinforcing cords 26a. Here, since the widest belt ply 25 after vulcanization has the small-diameter reinforcing cord 26b penetrated into the first ply segment 46 as described above, the belt ply 25 is more circumferential than the first and second ply segments 46, 47 before vulcanization. Longer direction length.

  If the widest belt ply 25 is configured as described above, the widest belt ply 25 can be easily formed, and the small diameter reinforcing cord 26b penetrates into an intermediate position between the normal diameter reinforcing cords 26a. Contact between the normal-diameter reinforcing cord 26a and the small-diameter reinforcing cord 26b is prevented, thereby preventing fretting wear.

  At this time, the gauges J and K of the coating rubbers 48 and 49 on the side where the first and second ply segments 46 and 47 are in close contact with each other are smaller than the gauges Q and R of the coating rubbers 48 and 49 on the side where they are separated from each other. In this state, if the first and second ply segments 46 and 47 are arranged in close contact with each other, the widest belt ply between the normal diameter reinforcing cord 26a and the small diameter reinforcing cord 26b due to compression deformation during vulcanization. The distance in the thickness direction of 25 can be easily reduced, and thereby the thickest belt ply 25 can be effectively prevented from being thickened.

  The widest belt ply 25 in which the normal diameter and small diameter reinforcing cords 26a and 26b are alternately embedded is, for example, passed between the calendar rolls in a state where the normal diameter and small diameter reinforcing cords are alternately arranged in parallel. The periphery of the normal diameter and small diameter reinforcing cords may be covered with a coating rubber and then molded by being attached to a tire intermediate and vulcanized, or the first and second ply segments 46 and 47 described above may be formed. After bonding together, the ply segments 46 and 47 may be bonded by passing between a pair of rollers, and then bonded to a tire intermediate body and vulcanized to be molded.

    5 and 6 are views showing Embodiment 2 of the present invention. In this embodiment, the belt layer 24 is composed of one (widest width) belt ply 52 that is narrower than the belt reinforcing layer 31, and the belt ply 52 is inclined with respect to the tire equator S with the same diameter as the conventional one. A large number of reinforcing cords 53 having an angle A of 40 to 70 degrees are embedded. In addition, a pair of split belt layers 54 are provided between the belt layer 24 and the belt reinforcing layer 31 so that the inner end in the width direction overlaps the outer end in the width direction of the widest belt ply 52. It arrange | positions in the position straddling the width direction outer end of the wide reinforcement | strengthening reinforcement plies 32 and 33, and the width direction inner end is located in the width direction inner side from the width direction outer end of the widest width reinforcement plies 32 and 33.

  In the divided belt layers 54, a plurality of reinforcing cords 55 having an inclination angle of 40 to 70 degrees with respect to the tire equator S are embedded in the same manner as the reinforcing cords 53. In this embodiment, the reinforcing cords are embedded. 55 is inclined at the same angle in the same direction as the reinforcing cord 53. The inclination direction of the reinforcing cord 55 may be opposite to the inclination direction of the reinforcing cord 53. In this case, the reinforcing cords 53 and 55 cross each other.

  Further, in this embodiment, the reinforcing cord 55 is alternately arranged with a normal diameter reinforcing cord 55a and a normal diameter reinforcing cord 55a having a smaller diameter than the normal diameter reinforcing cord 55a, like the widest belt ply 25 in the first embodiment. The outer end 56 of the small-diameter reinforcement cord 55b is protruded outward from the outer end 57 of the normal-diameter reinforcement cord 55a. In this embodiment, the inner end 58 of the small-diameter reinforcing cord 55b is also protruded inward from the inner end 59 of the normal-diameter reinforcing cord 55a, and the reduction in shear rigidity in the divided belt layer 54 is further effectively suppressed. .

  Here, similarly to the first embodiment, the above-described split belt layer 54 is also provided with the first ply segment in which the normal diameter reinforcing cord 55a is embedded, and the small diameter reinforcement having the same number of driving as the normal diameter reinforcing cord 55a. By vulcanizing the second ply segment in which the cord 55b is embedded with the small-diameter reinforcing cord 55b positioned between the normal-diameter reinforcing cord 55a, the first and second ply segments are separated. In addition to being integrated, the small-diameter reinforcing cord 55b can be configured to enter the first ply segment.

  And if comprised as mentioned above, like the said Embodiment 1, between the outer end 57 of the normal diameter reinforcement cord 55a and its surrounding rubber, and the outer end 56 of the small diameter reinforcement cord 55b, and its circumference Distortion occurs between the rubber and the distortion, the separation is effectively suppressed, and the distortion between the outer end 56 of the small diameter reinforcing cord 55b and the surrounding rubber is relatively small. And the occurrence of separation at the site can be effectively suppressed. Other configurations and operations are the same as those of the first embodiment.

    FIG. 7 is a diagram showing Embodiment 3 of the present invention. In this embodiment, a protective belt layer 62 that overlaps the widest belt ply 25 and is narrower than the widest reinforcing plies 32 and 33 is disposed outside the widest belt ply 25 in the first embodiment in the radial direction. is doing. Then, a reinforcing cord that is inclined within a range of 40 to 70 degrees with respect to the tire equator S is embedded in the protective belt layer 62, and the reinforcing cord is opposite to the reinforcing cord 26 in the widest belt ply 25. It is inclined to. In this way, both shear rigidity and cut resistance can be improved. Other configurations and operations are the same as those of the first embodiment.

    FIG. 8 is a diagram showing Embodiment 4 of the present invention. In this embodiment, a pair of narrow reinforcing layers 64 straddling the outer ends in the width direction of the widest width reinforcing plies 32 and 33 are arranged in close contact with the outer side in the radial direction of the widest belt ply 25, and these widths A large number of reinforcing cords are embedded in the narrow reinforcing layer 64 in a range of 40 to 70 degrees with respect to the tire equator S and inclined in the opposite direction to the reinforcing cord 26 in the widest belt ply 25. is doing. In this way, the circumferential rigidity at the portion where the narrow reinforcing layer 64 and the widest belt ply 25 overlap with each other increases, and the belt layer 24 at the outer end in the width direction of the belt reinforcing layer 31 is increased. Can be effectively suppressed. Other configurations and operations are the same as those of the first embodiment.

    In the above-described embodiment, the small-diameter reinforcing cords 26b and 55b are configured by one type of reinforcing cord. However, in the present invention, the small-diameter reinforcing cords 26b and 55b may be configured by two or more types of reinforcing cords having different diameters. In the first embodiment described above, the second ply segment 47 is disposed on the radially outer side of the first ply segment 46. However, in the present invention, contrary to the above, on the radially outer side of the second ply segment. You may make it arrange | position a 1st ply segment. Furthermore, in Embodiment 2 described above, the split belt layer 54 is disposed radially inward of the belt layer 24. However, in the present invention, the split belt layer may be disposed radially outward of the belt layer. .

    Next, the first test example will be described. In this test, the conventional tire 1 as shown in FIG. 1 provided with the widest belt ply in which all the reinforcing cords embedded inside have the same diameter as the conventional reinforcing cord, and the normal diameter reinforcing cord and the small diameter inside. Implementation as shown in FIGS. 1 and 2 with the widest belt ply in which the outer cords of the small-diameter reinforcing cords protrude outward from the outer ends of the normal-diameter reinforcing cords, with the reinforcing cords arranged alternately. Tires 1 and 2 were prepared.

  Here, the size of each of the tires is 435 / 45R22.5, and in each tire, the tire width W is 435 mm, and the width of the belt reinforcing layer (the width L of the widest reinforcing ply) is 300 mm. The width of the belt layer in the tire 1 is 380 mm, the distance between both outer ends in the width direction of the normal diameter reinforcing cord and the small diameter reinforcing cord in the working tires 1 and 2 is 350 mm and 380 mm, respectively, and the reinforcing cord in the belt layer of the conventional tire 1 In addition, the inclination angles A of the normal diameter and small diameter reinforcement cords of the implementation tires 1 and 2 with respect to the tire equator S are both 52 degrees rising to the left, the reinforcement cords in the belt layer of the conventional tire 1 and the ordinary diameter reinforcement cords of the implementation tires 1 and 2 The diameters of the tires 1 and 3 were 1.13 mm, and the diameters of the small diameter reinforcing cords of the tires 1 and 2 were 0.66 mm and 0.32 mm, respectively.

  Further, the belt reinforcing layer side and tread side coating rubber gauges of the widest belt ply in the conventional tire 1 were both 0.35 mm. On the other hand, in the implementation tires 1 and 2, the widest belt ply is composed of the first and second ply segments, but the adhesion side coating rubber gauges J and K in the first and second ply segments before vulcanization are 0.20 mm, respectively. 0.15 mm, and the separation side coating rubber gauges Q and R were both 0.35 mm.

  Next, each of the tires described above was mounted on a 14.00 × 22.5 rim, filled with an internal pressure of 900 kPa, and then run on the drum at 60 km / h until separation occurred while applying a load of 59.0 kN. As a result, assuming that the conventional tire 1 has an index of 100, the durability of the tires 1 and 2 was greatly improved to 132 and 142, respectively. In the conventional tire 1, separation occurred at the end of the widest belt ply, but in the working tires 1 and 2, separation occurred at the outer end of the small-diameter reinforcing cord.

    Next, a second test example will be described. In this test, the comparative tires 1 and 2 as shown in FIG. 5 provided with a split belt layer in which all the reinforcing cords embedded inside have the same diameter as the conventional reinforcing cords, and the normal diameter reinforcing cords inside Implementation tires 3 as shown in FIGS. 5 and 6, each having a split belt layer in which the outer ends of the small-diameter reinforcing cords protrude outward from the outer ends of the normal-diameter reinforcing cords, and the small-diameter reinforcing cords are alternately arranged. 4, 5, 6 were prepared.

  Here, the size of each of the tires is 435 / 45R22.5, and in each tire, the tire width W is 435 mm, the width of the belt reinforcing layer (the width L of the widest reinforcing ply) is 300 mm, the belt The width P of the layer is 280 mm, the inclination angle A with respect to the tire equator S of the reinforcing cord embedded in the belt layer of the comparative tire 1 and the implementation tires 3 and 4 is 52 degrees rising to the left, the comparison tire 2 and the implementation tires 5 and 6 The inclination angle A of the reinforcing cord embedded in the belt layer with respect to the tire equator S was 52 degrees to the right.

  On the other hand, the distance between the inner ends in the width direction of the divided belt layers in the comparative tires 1 and 2 and the distance between the inner ends of the normal diameter reinforcing cords in the implementation tires 3 to 6 are both 260 mm. The distance in the width direction from the inner end to the outer end of the normal diameter reinforcing cords in the tires 3 to 6 is 50 mm, and the tire equator S of the reinforcing cords in the comparative tires 1 and 2 and the normal diameter reinforcing cords in the embodiment tires 3 to 6 is used. The inclination angles of the tires were 52 degrees ascending to the left, and the diameters of the reinforcing cords in the split belt layers in the comparative tires 1 and 2 and the diameters of the normal diameter reinforcing cords in the implementation tires 3 to 6 were 1.13 mm.

  Further, the distance between the inner ends of the small diameter reinforcing cords in the implementation tires 3 to 6 is 240 mm, and the distance in the width direction from the inner end to the outer end of the small diameter reinforcement cords in the implementation tires 3 to 6 is 70 mm. The inclination angle of the small-diameter reinforcing cord in the tire equator S in each of -6 is 52 degrees ascending to the left, the diameter of the small-diameter reinforcing cord in the split belt layer in the implementation tires 3 and 5 is 0.66 mm, and the small-diameter reinforcement cord in the implementation tires 4 and 6 The diameter was 0.32 mm.

  Furthermore, the belt reinforcing layer side and belt layer side coating rubber gauges of the divided belt layers in the comparative tires 1 and 2 were both 0.35 mm. On the other hand, in the implementation tires 3 to 6, the split belt layer is composed of the first and second ply segments, but the adhesion side coating rubber gauges J and K in the first and second ply segments before vulcanization are 0.20 mm, 0.15 mm and the separation side coating rubber gauges Q and R were both 0.35 mm.

  Next, each of the tires described above was mounted on a 14.00 × 22.5 rim, filled with an internal pressure of 900 kPa, and then run on the drum at a speed of 60 km / h while applying a load of 59.0 kN. As a result, when the comparative tire 1 was index 100, the comparative tire 2 was 103, but the tires 3, 4, 5, and 6 were 129, 140, 131, and 144, respectively. . In comparison tires 1 and 2, separation occurred at the outer end in the width direction of the split belt layer, but in implementation tires 3 to 6, separation occurred at the outer end of the small-diameter reinforcing cord.

  The present invention can be applied to the industrial field of pneumatic tires in which a belt reinforcing layer is disposed between a carcass layer and a belt layer.

It is meridian sectional drawing which shows Embodiment 1 of this invention. It is the partially broken top view. FIG. 3 is a cross-sectional view taken along the arrow I-I in FIG. 2. It is sectional drawing of the 1st, 2nd ply segment vicinity before vulcanization. It is meridian sectional drawing which shows Embodiment 2 of this invention. It is the partially broken top view. It is meridian sectional drawing of the tread part vicinity which shows Embodiment 3 of this invention. It is meridian sectional drawing of the tread part vicinity which shows Embodiment 4 of this invention.

Explanation of symbols

11 ... Pneumatic tire 13 ... Bead core
18 ... Carcass layer 24 ... Belt layer
25 ... Belt ply 26 ... Reinforcement cord
26a ... Normal diameter reinforcement cord 26b ... Small diameter reinforcement cord
28 ... Tread 31 ... Belt reinforcement layer
32, 33 ... Reinforced ply 34, 35 ... Reinforcing element
42 ... Both outer ends 46 ... First ply segment
47 ... Second ply segment 54 ... Split belt layer
55 ... Reinforcement cord 55a ... Normal diameter reinforcement cord
55b ... Small diameter reinforcement cord 56 ... Outer end
57… Outer end 62… Protective belt layer
64 ... Narrow reinforcing layer

Claims (11)

    A carcass layer extending in a toroidal shape between a pair of bead cores, and at least one belt disposed radially outside the carcass layer and embedded with a plurality of reinforcing cords inclined with respect to the tire equator S A belt layer made of ply, a belt reinforcing layer made of at least one reinforcing ply disposed between the carcass layer and the belt layer, and having a reinforcing element extending substantially in the circumferential direction embedded therein, and the belt layer The widest belt ply that has the widest width and the width L of the widest reinforcing ply that is the widest width is not less than 0.6 times the tire width W. In a pneumatic tire having a width wider than the widest width reinforcing ply, a reinforcing cord embedded in the widest belt ply includes a normal diameter reinforcing cord and the normal tire The small-diameter reinforcing cord has a smaller diameter than the normal-diameter reinforcing cord and is arranged alternately with the normal-diameter reinforcing cord, and both outer ends of the small-diameter reinforcing cord are projected outward from both outer ends of the normal-diameter reinforcing cord. A pneumatic tire characterized by that.     A carcass layer extending in a toroidal shape between a pair of bead cores, and at least one belt disposed radially outside the carcass layer and embedded with a plurality of reinforcing cords inclined with respect to the tire equator S A belt layer made of ply, a belt reinforcing layer made of at least one reinforcing ply disposed between the carcass layer and the belt layer, and having a reinforcing element extending substantially in the circumferential direction embedded therein, and the belt layer A pneumatic tire in which a width L of the widest reinforcing ply, which is the widest width of the reinforcing plies, is 0.6 times or more of a tire width W. Overlaps the widthwise outer end of the widest belt ply, and the widthwise inner end is located on the inner side in the width direction than the widthwise outer end of the widest reinforcing ply, and the tire equator is inside. A pair of divided belt layers in which reinforcing cords inclined with respect to S are embedded, and the reinforcing cords embedded in the divided belt layers are composed of a normal diameter reinforcing cord and a normal diameter reinforcing cord. A small-diameter reinforcing cord comprising a small-diameter reinforcing cord arranged alternately with the normal-diameter reinforcing cord, and an outer end of the small-diameter reinforcing cord protruding outside the outer end of the normal-diameter reinforcing cord tire.     The pneumatic tire according to claim 1 or 2, wherein the diameter D of the small-diameter reinforcing cord is in a range of 0.1 to 0.7 times the diameter E of the normal-diameter reinforcing cord.     The pneumatic tire according to any one of claims 1 to 3, wherein a protruding amount M from the outer end of the normal diameter reinforcing cord to the outer end of the small diameter reinforcing cord in the width direction is within a range of 5 to 25 mm.     The pneumatic tire according to any one of claims 1 to 4, wherein an inclination angle A with respect to the tire equator S of a reinforcing cord embedded in the belt ply or the split belt layer is in a range of 40 to 70 degrees.     The widest belt ply includes a first ply segment in which a normal diameter reinforcing cord is embedded, and a second ply segment in which a small diameter reinforcing cord having the same number of driving as the normal diameter reinforcing cord is embedded. By performing vulcanization in a state where the small-diameter reinforcement cords are closely arranged so that the small-diameter reinforcement cords are positioned between the diameter-reinforcing cords, the first and second ply segments are integrated, and the small-diameter reinforcement cords enter the first ply segment. The pneumatic tire according to claim 1, wherein the pneumatic tire is configured as described above.     The split belt layer includes a first ply segment in which a normal diameter reinforcing cord is embedded and a second ply segment in which a small diameter reinforcing cord having the same number of driven reinforcement cords is embedded as a normal diameter. By vulcanizing in a state where the small-diameter reinforcing cords are closely arranged so that the small-diameter reinforcing cords are positioned between the reinforcing cords, the first and second ply segments are integrated, and the small-diameter reinforcing cords enter the first ply segment. The pneumatic tire according to claim 2, comprising:     The coating rubber gauges J and K on the side where the first and second ply segments are in close contact with each other are arranged in close contact with the coating rubber gauges Q and R on the side where they are separated from each other. Pneumatic tires.     A protective belt layer that is narrower than the widest width reinforcing ply is disposed at a position overlapping the widest belt ply, and 40 to 70 degrees in the direction opposite to the reinforcing cord in the widest belt ply is disposed in the protective belt layer. The pneumatic tire according to claim 1, wherein a reinforcing cord inclined within a range is embedded.     A pair of narrow reinforcing layers straddling the outer ends in the width direction of the widest width reinforcing ply are disposed, and a range of 40 to 70 degrees in the direction opposite to the reinforcing cord in the widest belt ply is disposed in the narrow reinforcing layer. The pneumatic tire according to claim 1, wherein a reinforcing cord inclined inside is embedded.     The pneumatic tire according to any one of claims 1 to 10, wherein the reinforcing element in the reinforcing ply extends substantially in the circumferential direction while being bent in a wave shape or a zigzag shape.

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