JP4918921B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having flat spot resistance.

  The pneumatic tire includes a tread portion that forms a tread surface, shoulder portions on both sides of the tread portion, and a sidewall portion and a bead portion that are sequentially continuous from the shoulder portions. In addition, a carcass is bridged over each bead portion. The carcass is arranged in a toroidal shape in the tire circumferential direction to form a tire skeleton. A belt layer is disposed on the outer side in the tire radial direction of the carcass, and a belt reinforcing layer is disposed on the outer side in the tire radial direction of the belt layer.

  For example, such a pneumatic tire generates heat when a vehicle equipped with the pneumatic tire travels at a high speed. And when a vehicle stops in the state which generate | occur | produced heat | fever and a pneumatic tire has touched the road surface for a long time as it is, a flat spot may generate | occur | produce. That is, when the pneumatic tire is in contact with the road surface for a long time at a high temperature, the tread surface of the tread portion that contacts the road surface is deformed by the influence of a vertical load such as the weight of the vehicle. Thereafter, when the temperature of the pneumatic tire decreases, residual strain is generated while the rubber and organic fibers constituting the pneumatic tire remain deformed. A flat spot is a flat part formed by this residual strain. When a flat spot is generated, the vehicle starts running and the deformation is maintained for a while. Therefore, the toroid shape becomes uneven with respect to the circumferential direction of the pneumatic tire, and vibration is generated to deteriorate the riding comfort. In addition, the steering stability may be reduced.

  Conventionally, for example, a pneumatic tire described in Patent Document 1 has a reinforcing layer composed of a composite cord composed of low-rigidity fibers and high-rigidity fibers. The reinforcing layer is provided adjacent to the carcass so that the composite cord is parallel to the carcass cord. The composite cord of the reinforcing layer has a low elastic region extending from the origin to the inflection point and a high elastic region exceeding the inflection point in the stress-elongation curve, and the elongation at the inflection point is 0.5. It is set in the range of [%] to 5.0 [%]. In addition, the stiffness index of the low elasticity region in the composite cord with respect to the stiffness index of the carcass is set to 50 [%] or less, and the stiffness index of the high elasticity region is set to 100 [%] or more.

JP 2006-298162 A

  According to the conventional pneumatic tire described above, the reinforcing layer is disposed adjacent to the carcass so that the composite cord is parallel to the carcass cord, so that the stress acting on the carcass from the inside of the tire can be reliably ensured by the reinforcing layer. Receiving and ensuring sufficient tire rigidity. In addition, when the tire is at a low air pressure, the occurrence of a flat spot is surely suppressed by the rigidity of the high elastic range of the composite cord, while in the normal running state, the deterioration of the riding comfort is prevented by the rigidity of the low elastic area.

  As described above, in the conventional pneumatic tire, it is possible to prevent the deterioration of the riding comfort while suppressing the occurrence of the flat spot by the reinforcing layer including the element for increasing the rigidity and the element for decreasing the rigidity. However, in a conventional pneumatic tire, the weight of the pneumatic tire increases due to the addition of a configuration such as a reinforcing layer.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can suppress generation | occurrence | production of a flat spot, without using an additional structure.

  In order to achieve the above object, in the pneumatic tire according to the present invention, a bead filler is provided inside each end of the pair of annular bead portions, and the toroidal arrangement is provided in the tire circumferential direction. And at least one layer of carcass having a plurality of carcass cords arranged side by side in the tire circumferential direction along the tire meridian direction, and a belt layer having at least two belts arranged on the outer side in the tire radial direction of the carcass The carcass cord of at least one layer of the carcass is intermittently provided at least at one location in a range from the outer end in the tire radial direction of the bead filler to the outermost end in the tire width direction of the belt layer. It has an intermittent cord provided with an intermittent portion, and a continuous cord continuous in the tire meridian direction

  According to this pneumatic tire, due to the intermittent portion of the intermittent cord, the number of ends of the carcass cord is substantially reduced in the range of the sidewall portion, and a flexible region can be obtained. Accordingly, the rigidity of the carcass is reduced in the range of the sidewall portion, and the amount of deflection in the range is increased, so that the stiffness in the tire radial direction is reduced, and bending deformation of the tread portion and the shoulder portion is suppressed. For this reason, deterioration of the rigidity in the tire width direction and the tire circumferential direction is suppressed, and the tire durability is improved. As a result, the vertical load such as the weight of the vehicle is absorbed in the range of the sidewall portion, and the deformation of the tread portion and the shoulder portion that are in contact with the road surface is suppressed, so that the occurrence of a flat spot can be suppressed. In addition, since the configuration of the carcass cord is changed, no additional configuration is used as before.

  Further, in the pneumatic tire according to the present invention, the tire outer shell in the range of the sidewall portion corresponding to the intermittent portion is provided with a groove portion continuous along the tire circumferential direction, and the depth d1 of the groove portion is It is set in the range of 1 [mm] ≦ d1 ≦ 4 [mm].

  According to this pneumatic tire, the combination of the groove portion and the intermittent portion of the intermittent cord facilitates the deformation of the sidewall portion, further suppressing the bending deformation of the tread portion and the shoulder portion, and further generating flat spots. Can be suppressed. In addition, when the depth d1 of the groove is less than 1 [mm], it is difficult to promote the deformation of the sidewall. On the other hand, when the depth d1 of the groove exceeds 4 [mm], the strength is insufficient due to a local decrease in the rigidity of the carcass, and the tire durability is deteriorated. For this reason, it is preferable that the depth d1 of the groove is set in a range of 1 [mm] ≦ d1 ≦ 4 [mm].

  Further, in the pneumatic tire according to the present invention, the intermittent cord portion made of the intermittent cord and the continuous cord portion made of the continuous cord are adjacent in the tire circumferential direction, and the sidewall portion corresponding to the continuous cord portion The tire outer shell in the range is provided with a recess.

  According to this pneumatic tire, due to the intermittent portion of the intermittent cord portion, the number of ends of the carcass cord is substantially reduced in the range of the sidewall portion, and a flexible region can be obtained. Accordingly, the rigidity of the carcass is reduced in the range of the sidewall portion, and the amount of deflection in the range is increased, so that the stiffness in the tire radial direction is reduced, and bending deformation of the tread portion and the shoulder portion is suppressed. For this reason, deterioration of the rigidity in the tire width direction and the tire circumferential direction is suppressed, and the tire durability is improved. As a result, the vertical load such as the weight of the vehicle is absorbed in the range of the sidewall portion, and the deformation of the tread portion and the shoulder portion that are in contact with the road surface is suppressed, so that the occurrence of a flat spot can be suppressed. In addition, since the configuration of the carcass cord is changed, no additional configuration is used as before. In addition, the combination of the concave portion provided corresponding to the continuous cord portion and the intermittent portion of the intermittent cord portion facilitates the deformation of the sidewall portion, further suppressing the bending deformation of the tread portion and the shoulder portion, and flat The generation of spots can be further suppressed.

  In the pneumatic tire according to the present invention, the total number n1 of the intermittent cord portions and the continuous cord portions is set in a range of 20 ≦ n1 ≦ 200.

  According to this pneumatic tire, when the total number n1 of the cord portions is less than 20, the strength is insufficient due to a local decrease in the rigidity of the carcass, and the tire durability is deteriorated. On the other hand, when the total number n1 of the cord portions exceeds 200, the effect on deformation is small, and it is difficult to obtain the effect of suppressing deformation (flat spots) of the tread portion and the shoulder portion. For this reason, it is preferable that the total number n1 of the code portions is set in a range of 20 ≦ n1 ≦ 200.

  In the pneumatic tire according to the present invention, the depth d2 of the recess is set in a range of 1 [mm] ≦ d2 ≦ 4 [mm].

  When the depth d2 of the recess is less than 1 [mm], it is difficult to promote the deformation of the sidewall portion. On the other hand, when the depth d2 of the recess exceeds 4 [mm], the strength is insufficient due to a local decrease in the rigidity of the carcass, and the tire durability is deteriorated. For this reason, it is preferable that the depth d2 of the recess is set in a range of 1 [mm] ≦ d2 ≦ 4 [mm].

  Moreover, in the pneumatic tire according to the present invention, the intermittent cord includes the carcass cord in which the cord end interval h of the intermittent portion is set in a range of h ≦ 10 [mm] and arranged in parallel in the tire circumferential direction. The number m1 per 50 is set in a range of 5 [lines] ≦ m1 ≦ 25 [lines].

  According to this pneumatic tire, the intermittent portion may have a cord end interval h of h = 0 [mm], and has an effect on deformation only by the cord end being cut, and the tread portion and the shoulder portion. An effect of suppressing deformation is obtained. On the other hand, when the cord end interval h exceeds 10 [mm], the strength of the carcass is insufficient and the tire durability is deteriorated. For this reason, in the intermittent cord, the cord end interval h of the intermittent portion is preferably set in a range of h ≦ 10 [mm]. Further, when the number m1 of the intermittent cords per 50 carcass cords is less than 5 [pieces], the effect on deformation is small, and it is difficult to obtain the effect of suppressing the deformation of the tread portion and the shoulder portion. On the other hand, when the number m1 of the intermittent cords per 50 carcass cords exceeds 25 [lines], the strength of the carcass is insufficient and the tire durability is deteriorated. For this reason, it is preferable that the number m1 of 50 carcass cords is set in a range of 5 [lines] ≦ m1 ≦ 25 [lines].

  In the pneumatic tire according to the present invention, the height H1 of the intermittent portion of the intermittent cord is (Ha-0) with respect to the height Ha and the tire cross-section height Ht of the carcass in the tire width direction maximum width. .15 × Ht) ≦ H1 ≦ (Ha + 0.15 × Ht).

  According to this pneumatic tire, the number of ends of the carcass cord is substantially reduced within the range in which the amount of deformation can be increased with the maximum width in the tire width direction of the sidewall portion, and a flexible region can be obtained. For this reason, it is possible to further suppress the occurrence of flat spots by further absorbing the vertical load such as the weight of the vehicle and further suppressing the deformation of the tread portion and the shoulder portion that are in contact with the road surface.

  In the pneumatic tire according to the present invention, when the carcass is provided in two layers, the intermittent cord is provided in any one of the two layers of the carcass.

  According to this pneumatic tire, when two layers of carcass are provided, if both the carcass cords include an intermittent cord, the strength of the carcass is insufficient and the tire durability is deteriorated. For this reason, when two layers of carcass are provided, the carcass cord in any one of the carcass includes an intermittent code, and the carcass cord in the other carcass does not include an intermittent code and includes only a continuous code. It is preferable to be included.

  In the pneumatic tire according to the present invention, when the carcass is provided with only one layer of the carcass, the end portion of the carcass is folded at the bead portion in the carcass. It is provided in the outer folding part.

  According to this pneumatic tire, when only one layer of the carcass is provided, if the intermittent portion is provided inside the bead portion before the end portion of the carcass is folded, the strength of the carcass is insufficient and the tire durability is reduced. Getting worse. For this reason, when only one layer of the carcass is provided, it is preferable to provide an intermittent portion at the outer folded portion that is folded.

  Further, in the pneumatic tire according to the present invention, the intermittent portion of the intermittent cord is set in a tire radial direction position in such a manner that the rigidity variation due to the volume variation in the tire circumferential direction due to the pattern of the tread portion is canceled out. It is characterized by.

  According to this pneumatic tire, the intermittent portion that is close to the portion having high rigidity due to the pattern of the tread portion is provided with a phase shifted toward the inside in the tire radial direction, so that the rigidity of the carcass is relatively low. On the other hand, an intermittent portion that is close to a portion having low rigidity due to the pattern of the tread portion is provided with a phase shifted toward the outer side in the tire radial direction so that the rigidity of the carcass is relatively high. In this way, by changing the rigidity of the carcass in the tire circumferential position and changing the degree of deformation of the sidewall portion in the tire circumferential position, the rigidity variation of the tread portion and the shoulder portion is offset, so the steering wheel and It is possible to suppress the deterioration of the uniformity (UF: uniformity) of the pneumatic tire that causes generation of vehicle vibration and vehicle interior noise.

  Further, in the pneumatic tire according to the present invention, each end is folded back by a pair of annular bead portions and arranged in a toroidal shape in the tire circumferential direction, and is arranged in parallel in the tire circumferential direction along the tire meridian direction. A pneumatic tire comprising at least one layer of carcass having a plurality of carcass cords and a belt layer having at least two belts arranged on the outer side in the tire radial direction of the carcass, wherein at least one layer of the carcass is A first cord portion in which the carcass cord is formed to a predetermined length and a second cord in which the length of the carcass cord is shorter than the first cord portion in the outer folded portion where the end portion is folded. Are formed adjacent to each other in the tire circumferential direction, and a recess is provided in the tire outer shell in the range of the sidewall portion corresponding to the first cord portion. And said that you are.

  According to this pneumatic tire, the number of ends of the carcass cord is substantially reduced in the range of the sidewall portion by the second cord portion formed with the length of the carcass cord shorter than that of the first cord portion. A region with the characteristics can be obtained. Accordingly, the rigidity of the carcass is reduced in the range of the sidewall portion, and the amount of deflection in the range is increased, so that the stiffness in the tire radial direction is reduced, and bending deformation of the tread portion and the shoulder portion is suppressed. For this reason, deterioration of the rigidity in the tire width direction and the tire circumferential direction is suppressed, and the tire durability is improved. As a result, the vertical load such as the weight of the vehicle is absorbed in the range of the sidewall portion, and the deformation of the tread portion and the shoulder portion that are in contact with the road surface is suppressed, so that the occurrence of a flat spot can be suppressed. In addition, since the configuration of the carcass cord is changed, no additional configuration is used as before. Furthermore, the combination of the carcass cord and the recess in the second cord portion facilitates the deformation of the sidewall portion, so that the bending deformation of the tread portion and the shoulder portion can be further suppressed, and the occurrence of flat spots can be further suppressed. .

  In the pneumatic tire according to the present invention, the total number n2 of the first cord portion and the second cord portion is set in a range of 20 ≦ n2 ≦ 200.

  According to this pneumatic tire, when the total number n2 of the cord portions is less than 20, the strength is insufficient due to a local decrease in the rigidity of the carcass, and the tire durability is deteriorated. On the other hand, when the total number n2 of cord portions exceeds 200, the effect on deformation is small, and it is difficult to obtain the effect of suppressing deformation (flat spots) of the tread portion and the shoulder portion. For this reason, it is preferable that the total number n2 of code portions is set in a range of 20 ≦ n2 ≦ 200.

  In the pneumatic tire according to the present invention, a difference t in length between the carcass cord of the first cord portion and the carcass cord of the second cord portion at the folded portion is 10 [mm] ≦ The ratio m2 of the number of the carcass cords in the second cord portion to the total number of the carcass cords in the first cord portion is set in a range of t ≦ 50 [mm], and 0.1 ≦ m2 ≦ 0.5. It is characterized by being set in the range of.

  According to this pneumatic tire, when the difference in length t between the carcass cord of the first cord portion and the carcass cord of the second cord portion is less than 10 [mm], the effect on deformation is small, It is difficult to obtain an effect of suppressing deformation of the tread portion and the shoulder portion. On the other hand, when the difference in length t between the carcass cord of the first cord portion and the carcass cord of the second cord portion exceeds 50 [mm], the strength of the carcass is insufficient and the tire durability is deteriorated. To do. For this reason, the difference in length t between the carcass cord of the first cord portion and the carcass cord of the second cord portion is set in the range of 10 [mm] ≦ t ≦ 50 [mm]. preferable. Further, when the ratio m2 of the number of carcass cords in the second cord portion to the total number of carcass cords in the first cord portion is less than 0.1, the effect on the deformation is small, and the deformation of the tread portion and the shoulder portion is suppressed. It is difficult to obtain the effect. On the other hand, when the ratio m2 of the number of carcass cords in the second cord portion to the total number of carcass cords in the first cord portion exceeds 0.5, the strength of the carcass is insufficient and tire durability is deteriorated. For this reason, it is preferable that the ratio m2 of the number of carcass cords in the second code portion to the total number of carcass cords in the first cord portion is set in a range of 0.1 ≦ m2 ≦ 0.5.

  In the pneumatic tire according to the present invention, the depth d3 of the recess is set in a range of 1 [mm] ≦ d3 ≦ 4 [mm].

  According to this pneumatic tire, when the depth d3 of the recess is less than 1 [mm], it is difficult to promote the deformation of the sidewall portion. On the other hand, when the depth d3 of the recess exceeds 4 [mm], the strength is insufficient due to the local decrease in the rigidity of the carcass, and the tire durability is deteriorated. For this reason, it is preferable that the depth d3 of the recess is set in a range of 1 [mm] ≦ d3 ≦ 4 [mm].

  In the pneumatic tire according to the present invention, the height H2 of the folded portion end of the second cord portion is (Ha) with respect to the height Ha and the tire cross-section height Ht of the carcass in the tire width direction maximum width. −0.15 × Ht) ≦ H2 ≦ (Ha + 0.15 × Ht).

  According to this pneumatic tire, the number of ends of the carcass cord is substantially reduced within the range in which the amount of deformation can be increased with the maximum width in the tire width direction of the sidewall portion, and a flexible region can be obtained. For this reason, it is possible to further suppress the occurrence of flat spots by further absorbing the vertical load such as the weight of the vehicle and further suppressing the deformation of the tread portion and the shoulder portion that are in contact with the road surface.

  In the pneumatic tire according to the present invention, the folded portion end of the second cord portion has a tire radial direction position set in a manner that cancels out the rigidity variation due to the volume variation in the tire circumferential direction due to the tread portion pattern. It is characterized by being.

  According to this pneumatic tire, the folded portion end of the second cord portion that is close to the portion having high rigidity due to the pattern of the tread portion is provided with a phase shifted toward the inner side in the tire radial direction, so that the rigidity of the carcass is relatively low. . On the other hand, the folded portion end of the second cord portion that is close to the portion having low rigidity due to the pattern of the tread portion is provided with a phase shifted toward the outer side in the tire radial direction so that the rigidity of the carcass is relatively high. In this way, by changing the rigidity of the carcass in the tire circumferential position and changing the degree of deformation of the sidewall portion in the tire circumferential position, the rigidity variation of the tread portion and the shoulder portion is offset, so the steering wheel and It is possible to suppress the deterioration of the uniformity (UF: uniformity) of the pneumatic tire that causes generation of vehicle vibration and vehicle interior noise.

  Further, in the pneumatic tire according to the present invention, the tread surface of the tread portion includes a plurality of different curvatures including at least a central arc positioned at the center in the tire width direction and a shoulder side arc positioned at the outermost side in the tire width direction. It is formed by a circular arc of a radius, and is seen from a tire meridian cross-sectional view in a state where it is incorporated in a normal rim and filled with 5% of the normal internal pressure, from the outermost end in the tire width direction of the belt layer to the outer side in the tire radial direction. An intersection of an imaginary line parallel to the tire radial direction and the profile of the tread surface is a reference point, an intersection of the tire equator surface and the profile of the tread surface is a center crown, and the reference point and the center crown The angle between the line connecting the two and the line parallel to the tire width direction is θ, the radius of curvature of the central arc is R1, and the curvature of the shoulder arc is half R2 and L as the reference development width that is the arc length from the tire equator plane to the inner edge position of the shoulder-side arc in the tire width direction, and the tread deployment width that is the arc length of the tread surface in the tire width direction. In the case of TDW, the tread surface satisfies 1 [degree] <θ <3 [degree], 5 <R1 / R2 <10, and 0.4 <L / (TDW / 2) <0.7. It is formed.

  According to this pneumatic tire, the profile variable factors of the angle θ, the radius of curvature R1 of the central arc, the radius of curvature R2 of the shoulder side arc, and the reference development width L are appropriately set, so that the tire width direction of the tread surface is increased. Since the curvature of the profile along the line approaches a straight line, it is possible to optimize both the steering stability performance and the flat spot resistance performance.

  In the pneumatic tire according to the present invention, the flatness is 55 [%] or less.

  According to this pneumatic tire, when applied to tires having a relatively long flatness ratio of 55 [%] or less in the tire width direction, the effect of improving flat spot resistance is more remarkably exhibited.

  The pneumatic tire according to the present invention can suppress the occurrence of flat spots without using an additional configuration.

  Embodiments of a pneumatic tire according to the present invention will be described below 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.

  In the following description, the tire radial direction means a direction orthogonal to the rotational axis of the pneumatic tire, the tire radial inner side is the side toward the rotational axis in the tire radial direction, and the tire radial outer side is in the tire radial direction. The side away from the rotation axis. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction is the side facing the tire equator plane in the tire width direction, and the outer side in the tire width direction is separated from the tire equator plane in the tire width direction. Say the side.

  The pneumatic tire described below is configured to be substantially symmetric with respect to the tire equatorial plane. The tire equator plane is a plane that is orthogonal to the rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane in the tire width direction. The tire equator line is a line on the tire equator surface along the circumferential direction of the pneumatic tire. Since the pneumatic tire described below is configured to be substantially symmetrical about the tire equatorial plane, the meridian when the pneumatic tire is cut on a plane passing through the rotation axis of the pneumatic tire is used. In the cross-sectional view, only one side centered on the tire equator plane is illustrated and only the one side is described, and description on the other side is omitted.

[Embodiment 1]
1 is a meridional sectional view of a pneumatic tire according to Embodiment 1 of the present invention, FIG. 2 is a schematic side view showing a carcass cord of a carcass in the pneumatic tire shown in FIG. 1, and FIG. 3 is FIG. 4 is a schematic side view showing a groove portion in the illustrated pneumatic tire, FIG. 4 is a schematic cross-sectional view showing the depth of the groove portion shown in FIG. 3, and FIG. 5 is a schematic view showing an intermittent portion of the intermittent cord shown in FIGS. FIG. 6 is a schematic meridional sectional view of a configuration in which two layers of carcass are provided, FIG. 7 is a schematic meridional sectional view of a configuration in which one layer of carcass is provided, and FIG. 8 is a schematic perspective view of the pneumatic tire shown in FIG. FIG. 9 is a chart showing the results of the performance test of the pneumatic tire according to the first embodiment of the present invention.

  As shown in FIG. 1, the pneumatic tire 1 according to the first embodiment includes a tread portion 2, shoulder portions 3 on both sides thereof, a sidewall portion 4 and a bead portion 5 successively from each shoulder portion 3. have. The pneumatic tire 1 includes a carcass 6, a belt layer 7, and a belt reinforcing layer 8.

  The tread portion 2 is exposed to the outside of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that contacts the road surface during traveling. The tread surface 21 has a plurality of (four in the first embodiment) circumferential main grooves 22 extending in the tire circumferential direction, and a plurality of compartments formed by the circumferential main grooves 22. The rib 23 which makes a land part is provided.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. Further, the sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire 1. The bead unit 5 includes a bead core 51 and a bead filler 52. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 52 is disposed in a space formed by folding the end of the carcass 6 outward in the tire width direction at the position of the bead core 51.

  The carcass 6 is configured such that each tire width direction end portion is folded with respect to the pair of bead portions 5 and is wound around in a toroidal shape in the tire circumferential direction to constitute a tire skeleton. The carcass 6 is a carcass cord 61 (see FIG. 2) such as organic fiber (nylon, polyester, etc.) or steel covered with a rubber material. A plurality of carcass cords 61 are arranged in the tire circumferential direction while being along the tire meridian direction perpendicular to the tire equator line of the pneumatic tire 1. The carcass 6 shown in FIG. 1 is composed of one layer, but may have a multilayer structure in order to improve rigidity. That is, the carcass 6 in the first embodiment is provided with at least one layer according to the desired rigidity. Further, the carcass cord 61 is orthogonal to the tire equator line, but the angle with respect to the tire equator line (tire circumferential direction) is substantially 90 degrees, and is −5 with reference to 90 degrees with respect to the tire equator line. Includes angles in the range of [degrees] to +5 [degrees].

  The belt layer 7 has a multilayer structure in which at least two belts 71 and 72 are laminated, and is disposed outside the carcass 6 in the tire radial direction so as to cover the carcass 6 in the tire circumferential direction. The belts 71 and 72 are made of a cord made of organic fibers (nylon, polyester, etc.) or steel covered with a rubber material, and the cords have a predetermined angle with respect to the tire circumferential direction, that is, the tire equator line. Has been placed. The belts 71 and 72 are arranged with their cords inclined in opposite directions with respect to the tire equator line.

  The belt reinforcing layer 8 is disposed outside the belt layer 7 in the tire radial direction and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 is made of an organic fiber (nylon, polyester, etc.) or a steel cord covered with a rubber material, and the cord is substantially 0 degrees (tire) with respect to the tire circumferential direction, that is, the tire equator line. It arrange | positions so that the angle with respect to the circumferential direction may become an angle of 10 degrees or less.

  As shown in FIG. 2, the carcass cord 61 in at least one layer of the carcass 6 has an intermittent cord 611 and a continuous cord 612. The intermittent cord 611 extends from the position of the normal line A (see FIG. 1) of the carcass 6 passing through the outer end of the bead filler 52 in the tire radial direction to the tire width direction of the belt layer 7 (the belt 71 having the maximum width in the tire width direction). In the range up to the position of the normal B (see FIG. 1) of the carcass 6 passing through the outermost end, that is, in the range of the sidewall portion 4, an intermittent portion 611 a is provided in which at least one portion is intermittent. The intermittent part 611a is provided by cutting or dividing the carcass cord 61 along the tire meridian direction. The continuous cord 612 is formed by continuously forming the carcass cord 61 along the tire meridian direction, and does not have the intermittent portion 611a.

  As described above, the pneumatic tire 1 including the carcass 6 having the intermittent cord 611 and the continuous cord 612 has substantially the number of ends of the carcass cord 61 in the range of the sidewall portion 4 by the intermittent portion 611a of the intermittent cord 611. Is reduced, and a flexible region is obtained. As a result, the rigidity of the carcass 6 is reduced in the range of the sidewall portion 4 and the amount of deflection in the range is increased, so that the rigidity in the tire radial direction is reduced, and bending deformation of the tread portion 2 and the shoulder portion 3 is suppressed. Is done. For this reason, deterioration of the rigidity in the tire width direction and the tire circumferential direction is suppressed, and the tire durability is improved. As a result, the vertical load such as the weight of the vehicle is absorbed in the range of the sidewall portion 4, and the deformation of the tread portion 2 and the shoulder portion 3 that are in contact with the road surface is suppressed, so that the occurrence of a flat spot can be suppressed. . In addition, since the configuration of the carcass cord 61 is changed, no additional configuration is used as before.

  Further, in the pneumatic tire 1 according to the first embodiment, as shown in FIGS. 1 and 3, in the tire circumferential direction on the tire outer shell in the range of the sidewall portion 4 corresponding to the intermittent portion 611 a of the intermittent cord 611. A groove portion 9 formed continuously in a band shape is provided. And as shown in FIG. 4, the depth d1 of the groove part 9 is set to the range of 1 [mm] <= d1 <= 4 [mm]. As shown in FIG. 4, the depth d1 of the groove 9 is defined by a straight line connecting each inflection point Q that forms the opening of the groove 9 that deforms from the tire outer shell to the groove 9 and the bottom of the groove 9. It is defined as the distance from a certain maximum depression position.

  According to such a configuration, the combination of the groove portion 9 and the intermittent portion 611a of the intermittent cord 611 facilitates the deformation of the sidewall portion 4, thereby further suppressing the bending deformation of the tread portion 2 and the shoulder portion 3, and the flat spot. Occurrence can be further suppressed. Moreover, when the depth d1 of the groove part 9 is less than 1 [mm], it is difficult to promote the deformation of the sidewall part 4. On the other hand, when the depth d1 of the groove 9 exceeds 4 [mm], the strength is insufficient due to a local decrease in the rigidity of the carcass 6 and tire durability is deteriorated. For this reason, it is preferable that the depth d1 of the groove part 9 is set in a range of 1 [mm] ≦ d1 ≦ 4 [mm].

  Further, in the pneumatic tire 1 according to the first embodiment, as illustrated in FIG. 5, in the intermittent cord 611, the cord end interval h of the intermittent portion 611 a is set in a range of h ≦ 10 [mm]. . Further, in the intermittent cord 611, the number m1 of 50 carcass cords 61 arranged in parallel in the tire circumferential direction is set in a range of 5 [lines] ≦ m1 ≦ 25 [lines].

  The intermittent portion 611a may have a cord end interval h of h = 0 [mm], and has an effect of deformation only by the cord end being cut, and an effect of suppressing deformation of the tread portion 2 and the shoulder portion 3. Is obtained. On the other hand, when the cord end interval h exceeds 10 [mm], the strength of the carcass 6 is insufficient and the tire durability is deteriorated. For this reason, in the intermittent cord 611, the cord end interval h of the intermittent portion 611a is preferably set in a range of h ≦ 10 [mm]. Moreover, when the number m1 per 50 is less than 5 [pieces], the effect on deformation is small, and the effect of suppressing the deformation of the tread portion 2 and the shoulder portion 3 is difficult to be obtained. On the other hand, when the number m1 per 50 exceeds 25 [pieces], the strength of the carcass 6 is insufficient and the tire durability is deteriorated. For this reason, it is preferable that the intermittent cord 611 has a number m1 of 50 carcass cords 61 set in a range of 5 [lines] ≦ m1 ≦ 25 [lines].

  Further, in the pneumatic tire 1 according to the first embodiment, as shown in FIG. 1, the height H of the center position in the tire radial direction of the intermittent portion 611 a of the intermittent cord 611 is the maximum width in the tire width direction of the carcass 6. Is set to a range of (Ha−0.15 × Ht) ≦ H ≦ (Ha + 0.15 × Ht).

  The tire cross-section height Ht is (outer diameter in the tire radial direction−rim diameter) / 2, and the tire equatorial plane from the inner radial side end of the bead portion 5 (that is, the position of the rim base 53). This is the height in the tire radial direction to the center crown CL, which is the intersection of S and the tread surface 21. Further, the height H at the center position in the tire radial direction of the intermittent portion 611a and the height Ha at the maximum width in the tire width direction of the carcass 6 are the tires from the rim base 53 of the bead portion 5 similarly to the tire cross-sectional height Ht. It is the height in the radial direction.

  According to such a configuration, the number of ends of the carcass cord 61 is substantially reduced within a range in which the deformation amount can be increased with the maximum width of the sidewall portion 4 in the tire width direction, and a flexible region can be obtained. For this reason, it is possible to further suppress the occurrence of flat spots by further absorbing the vertical load such as the weight of the vehicle and further suppressing the deformation of the tread portion 2 and the shoulder portion 3 that contact the road surface.

  Further, in the pneumatic tire 1 according to the first embodiment, as shown in FIG. 6, when two layers of the carcass 6 are provided, the intermittent cord 611 is provided in one of the two layers of the carcass 6. The other carcass 6 is provided with only a continuous cord 612.

  When the carcass 6 is provided in two layers and both the carcass cords 61 include the intermittent cord 611, the strength of the carcass 6 is insufficient and the tire durability is deteriorated. For this reason, when the carcass 6 is provided in two layers, the carcass cord 61 in one of the carcass 6 includes the intermittent cord 611, and the carcass cord 61 in the other carcass 6 includes the intermittent cord 611. It is preferable that only the continuous code 612 is included.

  Further, in the pneumatic tire 1 according to the first embodiment, as shown in FIG. 7, the intermittent portion 611 a of the intermittent cord 611 has a bead in the carcass 6 when only one layer of the carcass 6 is provided. The end portion of the carcass 6 is provided at the outer folded portion 6 a at the portion 5.

  When only one layer of the carcass 6 is provided, if the intermittent portion 611a is provided inside the bead portion 5 before the end portion of the carcass 6 is folded back, the strength of the carcass 6 is insufficient and the tire durability is deteriorated. For this reason, when only one layer of the carcass 6 is provided, it is preferable to provide the intermittent portion 611a on the outer folded portion 6a that is folded.

  Further, in the pneumatic tire 1 according to the first embodiment, as illustrated in FIG. 8, the intermittent portion 611 a of the intermittent cord 611 cancels the rigidity variation due to the volume variation in the tire circumferential direction due to the pattern of the tread portion 2. Thus, the position in the tire radial direction is set. Specifically, for example, when the size of the block 25 formed by providing the lug groove 24 connecting the circumferential main grooves 22 to the tread surface 21 of the tread portion 2 is large, the rigidity of the block 25 in the tire radial direction is high. Get higher. On the other hand, when the size of the block 25 is small, the rigidity of the block 25 in the tire radial direction is low. For this reason, the intermittent portion 611a in the vicinity of the large block 25 is provided at a low position on the bead portion 5 side (closer to the inner side in the tire radial direction) with a phase shifted to make the rigidity of the carcass 6 relatively low. On the other hand, the intermittent portion 611a of the portion adjacent to the small block 25 is provided at a high position on the shoulder portion 3 side (closer to the outer side in the tire radial direction) with a phase shifted to make the rigidity of the carcass 6 relatively high. In this way, by changing the rigidity of the carcass 6 at the tire circumferential position to change the degree of deformation of the sidewall part 4 at the tire circumferential position, the rigidity fluctuations of the tread part 2 and the shoulder part 3 are offset. Therefore, it is possible to suppress the deterioration of the uniformity (UF: uniformity) of the pneumatic tire that causes the vibrations of the steering wheel and the vehicle and the vehicle interior noise.

  Further, in the pneumatic tire 1 according to the first embodiment, as shown in FIG. 1, the tread surface 21 of the tread portion 2 has at least a central arc 21a located at the center in the tire width direction and the tire width direction outermost. It is formed of a plurality of arcs having different radii of curvature including the shoulder-side arc 21b located on the outside. And it is formed as follows in the tire meridian cross-sectional view in a state where it is incorporated in the normal rim and filled with 5% of the normal internal pressure. The regular rim here refers to an “applied rim” defined in JATMA, a “Design Rim” defined in TRA, or a “Measuring Rim” defined in ETRTO. The normal internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load means “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO.

  First, an imaginary line C that is assumed to be parallel to the tire radial direction is set from the outermost end in the tire width direction of the first belt 71 of the belt layer 7 to the outer side in the tire radial direction. An intersection of the virtual line C and the profile (contour) of the tread surface 21 is defined as a reference point D, and a line connecting the reference point D and the center crown CL is defined as a shoulder fall line E. An angle formed by the shoulder fall line E and a parallel line F parallel to the tire width direction and having the tire cross-section height Ht is defined as θ. The angle θ is an acute angle formed by the shoulder fall line E and the parallel line F. Further, the radius of curvature of the central arc 21a is R1, the radius of curvature of the shoulder-side arc 21b is R1, and the tire width direction inner end position G of the shoulder-side arc 21b from the tire equatorial plane S (the central arc 21a and the shoulder arc). The reference developed width which is the arc length up to the position where the side arc 21b continues) is L, and the tread developed width which is the arc length of the tread surface 21 in the tire width direction is TDW.

  The angle θ corresponds to the amount of sagging of the shoulder portion 3 continuous with both ends of the tread portion 2 with respect to the center crown CL. The tread development width TDW is defined as TDW = (L1 + L2) where L1 is the arc length in the tire width direction of the central arc 21a with the radius of curvature R1 and L2 is the arc length in the tire width direction of the shoulder side arc 21b with the radius of curvature R2. ) × 2. And in this Embodiment 1, since the arc of a different curvature radius is not set between the center part arc 21a and the shoulder side arc 21b in the tread surface 21, the tire in the center part arc 21a of the curvature radius R1 The arc length L1 in the width direction corresponds to the reference development width L. In the case where an arc having a different radius of curvature is set between the central arc 21a and the shoulder-side arc 21b on the tread surface 21, the reference development width L is the tire width direction of the shoulder-side arc 21b from the tire equatorial plane S. This is the sum of the arc lengths of arcs between the inner end position G. In other words, L = TDW / 2−L2.

  When each part of the pneumatic tire 1 is defined as described above, the tread surface 21 is set such that the angle θ is in the range of 1 [degree] <θ <3 [degree], and the curvature radius R1 and the curvature radius R2 The relationship is obtained by the following equation (1), and F1 (tread surface curvature radius ratio) obtained by the equation (1) is set in a range of 5 <F1 <10. Further, the relationship between the reference development width L and the tread development width TDW is obtained by the following equation (2), and F2 (expansion width ratio) obtained by this equation (2) is 0.4 <F2 <0.7. It is formed so as to be set within the range.

Formula (1) ... F1 = Rc / Rs
Formula (2) ... F2 = L / (TDW / 2)

  According to this configuration, the profile of the angle θ, the radius of curvature R1 of the central arc 21a, the radius of curvature R2 of the shoulder-side arc 21b, and the reference development width L (in other words, the arc length L1, the arc length L2, and the tread development width TDW). By setting the variable factors as described above, the curvature of the profile along the tire width direction of the tread surface 21 approaches a straight line, and therefore, optimization for compatibility between steering stability performance and flat spot resistance performance should be performed. Can do.

  That is, by setting the angle θ in the range of 1 [degree] <θ <3 [degree], the angle θ is smaller than 3 [degree]. The angle change in the vicinity of the shoulder portion 3 over 4 is reduced. That is, it is possible to reduce the amount of depression with respect to the center crown CL in the shoulder portion 3 continuous to both end portions of the tread portion 2, and to make the curvature of the tread surface 21 close to flat. On the other hand, since the angle θ is larger than 1 [degree], it is possible to prevent the appropriate shape as the pneumatic tire 1 from collapsing due to the angle θ being too small. Further, F1 obtained by the relational expression (1) between the curvature radius R1 and the curvature radius R2 is set in a range of 5 <F1 = Rc / Rs <10, and the reference development width L and the tread development width TDW are By setting F2 obtained by the relational expression (2) in a range of 0.4 <F2 = L / (TDW / 2) <0.7, the profile of the tread surface 21 is brought closer to a flatter shape, The contact pressure on the tread surface 21 can be made uniform. Thereby, the local deformation | transformation in the tread surface 21, the shoulder part 3, and the bead part 5, especially the belt reinforcement layer 8 arrange | positioned inside the tire radial direction of the tread part 2 in which the tread surface 21 was formed in the surface, and load , The local deformation of the bead filler 52, which has a great influence on the flat spot resistance, is suppressed. Thereby, the residual distortion at the time of thermal cooling of the pneumatic tire 1 can be reduced, and generation | occurrence | production of a flat spot can be suppressed.

  In addition, the pneumatic tire 1 according to the first embodiment is applied to a tire having a relatively long flatness ratio of 55 [%] or less, particularly with a relatively long distance in the tire width direction. There is an improvement effect. The flatness ratio is a ratio of the tire height Ht to the tire width W, as shown in FIG.

  In the first embodiment, performance tests on tire durability, uniformity (UF), and flat spot resistance were performed on a plurality of types of pneumatic tires having different conditions (see FIG. 9).

  In this performance test, a pneumatic tire having a tire size of 225 / 45ZR17 was assembled to a regular rim specified by JATMA, filled with the highest air pressure specified by JATMA, and the maximum load specified by JATMA was applied.

  In the tire durability performance test, after completion of the JATMA high-speed durability test with a drum diameter of 1707 mm, the test was continued at a speed of 10 km / h every 30 minutes until the tire was destroyed. Based on this result, index evaluation with Comparative Example 1 as a reference (100) is performed. This evaluation is preferable as the numerical value increases. Moreover, in the performance test of uniformity, RFV value was measured according to JISD4233. The air pressure at this time is 230 kPa, and the tire load is 5 kPa. Based on this result, index evaluation with Comparative Example 1 as a reference (100) is performed. This evaluation is preferable as the numerical value increases. In the performance test of flat spot resistance, the uniformity was measured in the same manner as described above, and after a preliminary run at 150 km / h for 30 minutes, the drum was stopped for 1 hour with a load applied. Thereafter, the tire uniformity is measured again, and the difference ΔRFV before and after the preliminary running of the radial force variation is used as an evaluation index. The smaller this difference ΔRFV, the better the flat spot resistance. Based on this result, index evaluation with Comparative Example 1 as a reference (100) is performed. This evaluation is preferable as the numerical value increases.

  The pneumatic tire of Comparative Example 1 does not have an intermittent portion (intermittent cord) and a groove portion, and the shoulder portion sagging amount θ, the tread surface curvature radius ratio (R1 / R2), and the deployment width ratio (L / (TDW). / 2)) has been optimized. On the other hand, the pneumatic tires of Examples 1 to 8 have an intermittent portion (intermittent cord), the cord end interval of the intermittent portion, the number of intermittent cords per 50 carcass cords, and the height of the intermittent portion. In the carcass, the position of the intermittent part, the depth of the groove part, the setting of the radial position of the intermittent part, the shoulder part sagging amount θ, the tread surface curvature radius ratio (R1 / R2) and the development width ratio (L / (TDW / 2) )) Has been optimized.

  As shown in the test results of FIG. 9, it can be seen that the pneumatic tires of Examples 1 to 8 each maintain durability within an allowable range and are excellent in uniformity and flat spot resistance.

[Embodiment 2]
FIG. 10 is a schematic side view showing a carcass cord of a carcass in the pneumatic tire according to the second embodiment of the present invention, and FIG. 11 shows the results of the performance test of the pneumatic tire according to the second embodiment of the present invention. It is a chart. In the second embodiment described below, the same parts as those in the first embodiment described above are denoted by the same reference numerals and the description thereof is omitted.

  In the pneumatic tire 1 according to the second embodiment, in the carcass 6, an intermittent cord portion 611S including at least one intermittent cord 611 provided with an intermittent portion 611a and a continuous cord including at least one continuous cord 612. The part 612S is provided adjacent to the tire circumferential direction. Further, a recess 91 is provided in the tire outer shell in the range of the sidewall portion 4 corresponding to the continuous cord portion 612S. The intermittent cord portion 611S is expressed in a range from one side of the intermittent cord 611 adjacent to the tire circumferential direction to the other side. The continuous cord portion 612S is expressed in a range from one side of the continuous cord 612 adjacent in the tire circumferential direction to the other side.

  As described above, the pneumatic tire 1 including the carcass 6 having the intermittent cord portion 611S and the continuous cord portion 612S has substantially the carcass cord 61 in the range of the sidewall portion 4 by the intermittent portion 611a of the intermittent cord portion 611S. The number of ends is reduced, and a flexible region is obtained. As a result, the rigidity of the carcass 6 is reduced in the range of the sidewall portion 4 and the amount of deflection in the range is increased, so that the rigidity in the tire radial direction is reduced, and bending deformation of the tread portion 2 and the shoulder portion 3 is suppressed. Is done. For this reason, deterioration of the rigidity in the tire width direction and the tire circumferential direction is suppressed, and the tire durability is improved. As a result, the vertical load such as the weight of the vehicle is absorbed in the range of the sidewall portion 4, and the deformation of the tread portion 2 and the shoulder portion 3 that are in contact with the road surface is suppressed, so that the occurrence of a flat spot can be suppressed. . In addition, since the configuration of the carcass cord 61 is changed, no additional configuration is used as before. Furthermore, the combination of the concave portion 91 and the intermittent portion 611a of the intermittent cord portion 611S facilitates the deformation of the sidewall portion 4, thereby further suppressing the bending deformation of the tread portion 2 and the shoulder portion 3 and generating a flat spot. It can be further suppressed.

  In the pneumatic tire 1 according to the second embodiment, the total number n1 of the intermittent cord portion 611S and the continuous cord portion 612S is set in a range of 20 ≦ n1 ≦ 200.

  When the total number n1 of the cord portions 611S and 612S is less than 20, the strength is insufficient due to a local decrease in the rigidity of the carcass 6 and tire durability is deteriorated. On the other hand, when the total number n1 of the cord portions 611S and 612S exceeds 200, the effect on the deformation is small, and it is difficult to obtain the effect of suppressing the deformation (flat spot) of the tread portion 2 and the shoulder portion 3. For this reason, it is preferable that the total number n1 of the code portions 611S and 612S is set in a range of 20 ≦ n1 ≦ 200.

  In the pneumatic tire 1 according to the second embodiment, as shown in FIG. 4, the depth d2 of the recess 91 is set in a range of 1 [mm] ≦ d2 ≦ 4 [mm]. As shown in FIG. 4, the depth d <b> 2 of the recess 91 is a straight line that connects each inflection point Q that forms an opening of the groove 9 that deforms from the tire outer shell to the groove 9, and the bottom of the groove 9. It is defined as the distance from the maximum depression position.

  When the depth d2 of the recess 91 is less than 1 [mm], it is difficult to promote the deformation of the sidewall portion 4. On the other hand, when the depth d2 of the recess 91 exceeds 4 [mm], the strength is insufficient due to a local decrease in the rigidity of the carcass 6 and tire durability is deteriorated. For this reason, it is preferable that the depth d2 of the recess 91 is set in a range of 1 [mm] ≦ d2 ≦ 4 [mm].

  In the pneumatic tire 1 according to the second embodiment, as in the first embodiment described above, in the intermittent cord 611, the cord end interval h of the intermittent portion 611a is set in a range of h ≦ 10 [mm]. It is preferable that this is done (see FIG. 5). Furthermore, it is preferable that the number m1 of 50 carcass cords 61 arranged in parallel in the tire circumferential direction is set in a range of 5 [lines] ≦ m1 ≦ 25 [lines].

  In the pneumatic tire 1 according to the second embodiment, as in the first embodiment described above, the height H of the center position in the tire radial direction of the intermittent portion 611a of the intermittent cord 611 is the tire width of the carcass 6. It is preferable that the range Ha (0.15 × Ht) ≦ H ≦ (Ha + 0.15 × Ht) is set with respect to the height Ha at the maximum width in the direction and the tire cross-section height Ht (see FIG. 1). ).

  Further, in the pneumatic tire 1 according to the second embodiment, similarly to the first embodiment described above, when two layers of the carcass 6 are provided, the pneumatic tire 1 is intermittently connected to any one of the two layers of the carcass 6. It is preferable that the cord 611 is provided and the other carcass 6 is provided with only the continuous cord 612 (see FIG. 6).

  In the pneumatic tire 1 according to the second embodiment, as in the first embodiment described above, the intermittent portion 611a of the intermittent cord 611 has the carcass 6 when only one layer of the carcass 6 is provided. The bead portion 5 is preferably provided on the outer folded portion 6a where the end portion of the carcass 6 is folded (see FIG. 7).

  Further, in the pneumatic tire 1 according to the second embodiment, as in the first embodiment described above, the intermittent portion 611a of the intermittent cord 611 has a rigidity variation due to a volume variation in the tire circumferential direction due to the pattern of the tread portion 2. It is preferable that the position in the tire radial direction is set in such a manner that cancels out (see FIG. 8).

  Further, in the pneumatic tire 1 according to the second embodiment, as in the first embodiment described above, in the meridional section of the tire in a state where it is incorporated in a normal rim and filled with 5% of the normal internal pressure, The sagging angle (amount) θ of the shoulder portion 3 is set in the range of 1 [degree] <θ <3 [degree], the tread surface curvature radius ratio F1 is set in the range of 5 <F1 <10, and the unfolding width ratio It is preferable that F2 is formed in a range of 0.4 <F2 <0.7 (see FIG. 1).

  In the pneumatic tire 1 according to the second embodiment, as in the first embodiment described above, the pneumatic tire 1 is particularly applied to a tire having a relatively long flatness of 55 [%] or less in the tire width direction.

  In the second embodiment, performance tests regarding tire durability, steering stability, uniformity (UF), and flat spot resistance were performed on a plurality of types of pneumatic tires having different conditions (see FIG. 11).

  In this performance test, a pneumatic tire having a tire size of 225 / 45ZR17 was assembled to a regular rim specified by JATMA, filled with the highest air pressure specified by JATMA, and the maximum load specified by JATMA was applied.

  The evaluation method is the same as that in the first embodiment described above for the tire durability, uniformity, and flat spot resistance performance tests, and index evaluation is performed with the comparative example 2 as a reference (100). This evaluation is preferable as the numerical value increases. In the performance test of steering stability, the pneumatic tire was mounted on a vehicle, and the feeling was evaluated by a 10-point method by five test drivers on a test course and a circuit. Based on this result, index evaluation is performed with the comparative example 2 as a reference (100). This evaluation is preferable as the numerical value increases.

  The pneumatic tire of Comparative Example 2 does not have the intermittent cord portion and the continuous cord portion, and the shoulder portion sagging amount θ, the tread surface curvature radius ratio (R1 / R2), and the development width ratio (L / (TDW / 2)) has been optimized. The pneumatic tire of Comparative Example 3 has an intermittent cord portion and a continuous cord portion, but the total number of cord portions is 15. On the other hand, the pneumatic tires of Examples 9 to 16 have an intermittent cord portion and a continuous cord portion, the total number of cord portions, the cord end interval of the intermittent portion, the number of intermittent cords per 50 carcass cords, The depth of the concave portion, the height of the intermittent portion, the position of the intermittent portion in the carcass, the shoulder portion sagging amount θ, the tread surface curvature radius ratio (R1 / R2) and the unfolded width ratio (L / (TDW / 2)), respectively. It has been optimized.

  As shown in the test results of FIG. 11, in the pneumatic tires of Examples 9 to 16, durability and steering stability are maintained within an allowable range, respectively, and excellent in uniformity and flat spot resistance. I understand.

[Embodiment 3]
FIG. 12 is a schematic side view showing a carcass cord of a carcass in the pneumatic tire according to the third embodiment of the present invention, and FIG. 13 shows the results of the performance test of the pneumatic tire according to the third embodiment of the present invention. It is a chart. In the third embodiment described below, the same parts as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the pneumatic tire 1 according to the third embodiment, the carcass cord 61 in the carcass 6 of at least one layer has a long cord 614 (described above) whose cord length is a predetermined length in the outer folded portion 6a where the end portion is folded. The long code portion (first code portion) 614S composed of the continuous code 612 of the first embodiment and the second embodiment) and the short code portion (first code portion) composed of the short code 613 having a shorter code length than the long code 614 2 cord portion) 613S is adjacent in the tire circumferential direction. Further, a recess 92 is provided in the tire outer shell in the range of the sidewall portion 4 corresponding to the long cord portion 614S.

  Thus, in the pneumatic tire 1 including the carcass 6 having the short cord portion 613S and the long cord portion 614S, the end number of the carcass cord 61 is substantially increased in the range of the sidewall portion 4 due to the short cord portion 613S. A reduced and flexible area is obtained. As a result, the rigidity of the carcass 6 is reduced in the range of the sidewall portion 4 and the amount of deflection in the range is increased, so that the rigidity in the tire radial direction is reduced, and bending deformation of the tread portion 2 and the shoulder portion 3 is suppressed. Is done. For this reason, deterioration of the rigidity in the tire width direction and the tire circumferential direction is suppressed, and the tire durability is improved. As a result, the vertical load such as the weight of the vehicle is absorbed in the range of the sidewall portion 4, and the deformation of the tread portion 2 and the shoulder portion 3 that are in contact with the road surface is suppressed, so that the occurrence of a flat spot can be suppressed. . In addition, since the configuration of the carcass cord 61 is changed, no additional configuration is used as before. Further, the combination of the concave portion 92 and the short cord 613 of the short cord portion 613S facilitates the deformation of the sidewall portion 4, thereby further suppressing the bending deformation of the tread portion 2 and the shoulder portion 3 and generating a flat spot. It can be further suppressed.

  In the pneumatic tire 1 according to the third embodiment, the total number n2 of the short cord portion 613S and the long cord portion 614S is set in a range of 20 ≦ n2 ≦ 200.

  When the total number n2 of the cord portions 613S and 614S is less than 20, the strength is insufficient due to a local decrease in the rigidity of the carcass 6 and tire durability is deteriorated. On the other hand, when the total number n2 of the cord portions 613S and 614S exceeds 200, the effect on the deformation is small, and it is difficult to obtain the effect of suppressing the deformation (flat spot) of the tread portion 2 and the shoulder portion 3. For this reason, it is preferable that the total number n2 of the code portions 613S and 614S is set in a range of 20 ≦ n2 ≦ 200.

  Further, in the pneumatic tire 1 according to the third embodiment, the difference in length t between the short cord 613 of the short cord portion 613S and the folded portion 6a of the long cord 614 of the long cord portion 614S is 10 [mm. ] ≦ t ≦ 50 [mm]. Further, the ratio m2 of the number of short codes 613 to the total number of long codes 614 is set in a range of 0.1 ≦ m2 ≦ 0.5.

  When the difference in length t between the short cord 613 and the long cord 614 at the folded portion 6a is less than 10 [mm], the effect on the deformation is small, and the effect of suppressing the deformation of the tread portion 2 and the shoulder portion 3 is obtained. It's hard to be done. On the other hand, when the difference in length t between the short cord 613 and the long cord 614 at the folded portion 6a exceeds 50 [mm], the strength of the carcass 6 is insufficient and the tire durability is deteriorated. For this reason, it is preferable that the difference t between the short cord 613 and the long cord 614 at the folded portion 6a is set in a range of 10 [mm] ≦ t ≦ 50 [mm]. Further, when the ratio m2 of the number of the short cords 613 to the total number of the long cords 614 is less than 0.1, the effect on the deformation is small, and it is difficult to obtain the effect of suppressing the deformation of the tread portion 2 and the shoulder portion 3. On the other hand, when the ratio m2 of the number of the short cords 613 to the total number of the long cords 614 exceeds 0.5, the strength of the carcass 6 is insufficient and the tire durability is deteriorated. For this reason, it is preferable that the ratio m2 of the number of the short codes 613 to the total number of the long codes 614 is set in a range of 0.1 ≦ m2 ≦ 0.5.

  In the pneumatic tire 1 according to the third embodiment, as shown in FIG. 4, the depth d3 of the recess 92 is set in the range of 1 [mm] ≦ d3 ≦ 4 [mm]. As shown in FIG. 4, the depth d <b> 3 of the recess 92 is a straight line connecting each inflection point Q that forms an opening of the groove 9 that deforms from the tire outer shell to the groove 9, and the bottom of the groove 9. It is defined as the distance from the maximum depression position.

  According to such a configuration, when the depth d3 of the recess 92 is less than 1 [mm], it is difficult to promote the deformation of the sidewall portion 4. On the other hand, when the depth d3 of the concave portion 92 exceeds 4 [mm], the strength is insufficient due to a local decrease in the rigidity of the carcass 6 and tire durability is deteriorated. For this reason, it is preferable that the depth d3 of the recess 92 is set in a range of 1 [mm] ≦ d3 ≦ 4 [mm].

  In the pneumatic tire 1 according to the third embodiment, the height H2 at the end of the folded portion 6a of the short cord portion 613S is set to the height Ha and the tire cross-section height Ht at the maximum width in the tire width direction. On the other hand, (Ha−0.15 × Ht) ≦ H2 ≦ (Ha + 0.15 × Ht) is set.

  According to such a configuration, the number of ends of the carcass cord 61 is substantially reduced within a range in which the deformation amount can be increased with the maximum width of the sidewall portion 4 in the tire width direction, and a flexible region can be obtained. For this reason, it is possible to further suppress the occurrence of flat spots by further absorbing the vertical load such as the weight of the vehicle and further suppressing the deformation of the tread portion 2 and the shoulder portion 3 that contact the road surface.

  Further, in the pneumatic tire 1 according to the third embodiment, the end of the folded portion 6a of the short cord portion 613S cancels the stiffness variation due to the volume variation in the tire circumferential direction due to the pattern of the tread portion 2, and the tire radial direction The position is set. Specifically, as shown in FIG. 8, for example, when the size of a block 25 formed by providing a lug groove 24 that connects the circumferential main grooves 22 on the tread surface 21 of the tread portion 2 is large, this block In the tire radial direction of 25, rigidity becomes high. On the other hand, when the size of the block 25 is small, the rigidity of the block 25 in the tire radial direction is low. For this reason, the folded portion 6a end of the short cord portion 613S in the portion close to the large block 25 is provided at a low position on the bead portion 5 side (inward in the tire radial direction) with a phase shifted, so that the rigidity of the carcass 6 is relatively make low. On the other hand, the end of the folded portion 6a of the short cord portion 613S in the vicinity of the small block 25 is provided at a high position on the shoulder portion 3 side (outward in the tire radial direction) with a phase shifted, so that the rigidity of the carcass 6 is relatively high. To do. In this way, by changing the rigidity of the carcass 6 at the tire circumferential position to change the degree of deformation of the sidewall part 4 at the tire circumferential position, the rigidity fluctuations of the tread part 2 and the shoulder part 3 are offset. Therefore, it is possible to suppress the deterioration of the uniformity (UF: uniformity) of the pneumatic tire that causes the vibrations of the steering wheel and the vehicle and the vehicle interior noise.

  Further, in the pneumatic tire 1 according to the third embodiment, as in the first embodiment described above, in the meridional section of the tire in a state where it is incorporated in the normal rim and filled with 5% of the normal internal pressure, The sagging angle (amount) θ of the shoulder portion 3 is set in the range of 1 [degree] <θ <3 [degree], the tread surface curvature radius ratio F1 is set in the range of 5 <F1 <10, and the unfolding width ratio It is preferable that F2 is formed in a range of 0.4 <F2 <0.7 (see FIG. 1).

  In the pneumatic tire 1 according to the third embodiment, as in the first embodiment described above, the pneumatic tire 1 is particularly applied to a tire having a relatively long flatness of 55 [%] or less in the tire width direction.

  In the third embodiment, performance tests on tire durability, steering stability, uniformity (UF), and flat spot resistance were performed on a plurality of types of pneumatic tires having different conditions (see FIG. 13).

  In this performance test, a pneumatic tire having a tire size of 225 / 45ZR17 was assembled to a regular rim specified by JATMA, filled with the highest air pressure specified by JATMA, and the maximum load specified by JATMA was applied. Moreover, the evaluation method is the same as that of the second embodiment described above.

The pneumatic tire of Comparative Example 4 does not have the short cord portion and the long cord portion, and the shoulder portion sagging amount θ, the tread surface curvature radius ratio (R1 / R2), and the deployment width ratio (L / (TDW / 2)) has been optimized. On the other hand, the pneumatic tires of Examples 17 to 22 have a short cord portion and a long cord portion,
The total number of cords, the difference in the length of the folded portion between the short cord and the long cord, the ratio of the number of short cords to the total number of long cords, the depth of the recess, the height of the end of the folded portion of the short cord, and the amount of shoulder drop θ, the tread surface curvature radius ratio (R1 / R2), and the development width ratio (L / (TDW / 2)) are optimized.

  As shown in the test results of FIG. 13, in the pneumatic tires of Example 17 to Example 22, durability and steering stability are maintained within an allowable range, respectively, and excellent in uniformity and flat spot resistance. I understand.

  As described above, the pneumatic tire according to the present invention is suitable for suppressing the occurrence of flat spots without using an additional configuration.

1 is a meridional sectional view of a pneumatic tire according to a first embodiment of the present invention. FIG. 2 is a schematic side view showing a carcass cord of a carcass in the pneumatic tire shown in FIG. 1. It is a schematic side view showing the groove part in the pneumatic tire shown in FIG. It is a schematic sectional drawing showing the depth of the groove part shown in FIG. It is the schematic showing the intermittent part of the intermittent code | cord | chord shown in FIG. 2 and FIG. It is a schematic meridional sectional view of a form in which two layers of carcass are provided. It is a schematic meridional sectional view of a form in which one layer of carcass is provided. It is a schematic perspective view of the pneumatic tire shown in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning Embodiment 1 of this invention. It is a schematic side view showing the carcass cord of the carcass in the pneumatic tire concerning Embodiment 2 of this invention. It is a graph which shows the result of the performance test of the pneumatic tire concerning Embodiment 2 of this invention. It is a schematic side view showing the carcass cord of the carcass in the pneumatic tire concerning Embodiment 3 of the present invention. It is a graph which shows the result of the performance test of the pneumatic tire concerning Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 21 Tread surface 21a Center part circular arc 21b Shoulder side circular arc 22 Circumferential main groove 23 Rib 24 Lag groove 25 Block 3 Shoulder part 4 Side wall part 5 Bead part 51 Bead core 52 Bead filler 53 Rim base 6 Carcass 6a Return part 61 Carcass cord 611 Intermittent code 611a Intermittent part 611S Intermittent cord part 612 Continuous code 612S Continuous cord part 613 Short code 613S Short cord part (second cord part)
614 long code 614S long code part (first code part)
7 Belt layer 71, 72 Belt 8 Belt reinforcing layer 9 Groove portion 91 Recess portion 92 Recess portion CL Center crown F1 Tread surface curvature radius ratio F2 Development width ratio h Cord end interval L Reference development width L1 Arc length of central arc L2 Shoulder side arc Arc length m1 Number of intermittent cords per 50 carcass cords m2 Ratio of the number of short cords to the total number of long cords n1 Total number of intermittent cord portions and continuous cord portions n2 Short cord portion (second cord portion) and long cord Total number of parts (first code part) Q Inflection point R1 Curvature radius of central arc R2 Curvature radius of shoulder side arc S Tire equatorial plane t Difference in length of folded part between short cord and long cord TDW Tread development width W Tire width θ Shoulder depression angle

Claims (18)

A pair of annular bead portions are provided with a bead filler on the inner side where each end is folded back, arranged in a toroidal shape in the tire circumferential direction, and juxtaposed in the tire circumferential direction along the tire meridian direction. In a pneumatic tire provided with at least one carcass having a plurality of carcass cords and a belt layer having at least two belts arranged on the outer side in the tire radial direction of the carcass,
The carcass cord of at least one layer of the carcass is provided with an intermittent cord provided with an intermittent portion where at least one portion is intermittent in a range from the outer end in the tire radial direction of the bead filler to the outermost end in the tire width direction of the belt layer. And a continuous cord continuous in the tire meridian direction.   A groove portion continuous along the tire circumferential direction is provided in the tire outer shell in the range of the sidewall portion corresponding to the intermittent portion, and the depth d1 of the groove portion is 1 [mm] ≦ d1 ≦ 4 [mm]. The pneumatic tire according to claim 1, wherein the pneumatic tire is set in a range of   The intermittent cord portion made of the intermittent cord and the continuous cord portion made of the continuous cord are adjacent in the tire circumferential direction, and a recess is provided in the tire outer shell in the range of the sidewall portion corresponding to the continuous cord. The pneumatic tire according to claim 1.   The pneumatic tire according to claim 3, wherein a total number n1 of the intermittent cord portions and the continuous cord portions is set in a range of 20 ≦ n1 ≦ 200.   The pneumatic tire according to claim 3 or 4, wherein a depth d2 of the recess is set in a range of 1 [mm] ≤ d2 ≤ 4 [mm].   In the intermittent cord, the cord end interval h of the intermittent portion is set in a range of h ≦ 10 [mm], and the number m1 of 50 carcass cords arranged in parallel in the tire circumferential direction is 5 [ The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is set in a range of [book] ≦ m1 ≦ 25 [book].   The height H1 of the intermittent portion of the intermittent cord is (Ha−0.15 × Ht) ≦ H1 ≦ (Ha + 0...) With respect to the height Ha and the tire cross-section height Ht of the carcass in the tire width direction maximum width. The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire is set in a range of 15 x Ht).   The said intermittent cord is provided in any one of the said carcass of two layers, when the said carcass is provided in two layers, The any one of Claims 1-7 characterized by the above-mentioned. Pneumatic tire.   When the carcass is provided with only one layer, the intermittent portion of the intermittent cord is provided in an outer folded portion where an end portion of the carcass is folded at the bead portion. The pneumatic tire according to any one of claims 1 to 8, wherein   10. The tire radial direction position is set in a manner in which the intermittent portion of the intermittent cord cancels out a stiffness variation due to a volume variation in a tire circumferential direction due to a pattern of a tread portion. Or a pneumatic tire according to claim 1. At least one layer having a plurality of carcass cords in which each end portion is folded at a pair of annular bead portions and arranged in a toroidal shape in the tire circumferential direction, and arranged in parallel in the tire circumferential direction along the tire meridian direction In a pneumatic tire comprising a carcass and a belt layer having at least two belts arranged on the outer side in the tire radial direction of the carcass,
The carcass of at least one layer includes a first cord portion in which the carcass cord is formed in a predetermined length at an outer folded portion where an end portion is folded, and the length of the carcass cord than the first cord portion. Is formed adjacent to the second cord portion formed in the tire circumferential direction, and the tire outer shell in the range of the sidewall portion corresponding to the first cord portion is provided with a recess. Pneumatic tires.   12. The pneumatic tire according to claim 11, wherein a total number n2 of the first cord portion and the second cord portion is set in a range of 20 ≦ n2 ≦ 200.   The length difference t at the folded portion between the carcass cord of the first cord portion and the carcass cord of the second cord portion is set in a range of 10 [mm] ≦ t ≦ 50 [mm]. The ratio m2 of the number of the carcass cords in the second cord portion to the total number of the carcass cords in the first cord portion is set in a range of 0.1 ≦ m2 ≦ 0.5. The pneumatic tire according to claim 11 or 12.   The pneumatic tire according to any one of claims 11 to 13, wherein a depth d3 of the recess is set in a range of 1 [mm] ≤ d3 ≤ 4 [mm].   The height H2 of the folded portion end of the second cord portion is (Ha−0.15 × Ht) ≦ H2 ≦ (the height Ha of the carcass in the tire width direction maximum width and the tire cross-section height Ht). The pneumatic tire according to any one of claims 11 to 14, wherein the pneumatic tire is set in a range of (Ha + 0.15 x Ht).   The tire radial direction position is set in the aspect in which the folded portion end in the second cord portion cancels out the stiffness variation due to the volume variation in the tire circumferential direction due to the pattern of the tread portion. A pneumatic tire according to any one of the above. The tread surface of the tread portion is formed by an arc having a plurality of different radii of curvature including at least a central arc located at the center in the tire width direction and a shoulder side arc located at the outermost side in the tire width direction.
In the meridional section of the tire with 5% of the normal internal pressure filled in the normal rim,
An imaginary line imaginary parallel to the tire radial direction from the outermost end in the tire width direction of the belt layer to the outer side in the tire radial direction, and an intersection of the profile of the tread surface as a reference point,
The intersection of the tire equator surface and the profile of the tread surface is the center crown,
An angle formed by a line connecting the reference point and the center crown and a line parallel to the tire width direction is θ,
The radius of curvature of the central arc is R1,
The radius of curvature of the shoulder side arc is R2,
L is a reference developed width that is an arc length from the tire equatorial plane to the inner end position in the tire width direction of the shoulder side arc.
When the tread development width, which is the arc length of the tread surface in the tire width direction, is TDW,
The tread surface is formed to satisfy 1 [degree] <θ <3 [degree], 5 <R1 / R2 <10, and 0.4 <L / (TDW / 2) <0.7. The pneumatic tire according to any one of claims 1 to 16.   The flat tire according to any one of claims 1 to 17, wherein a flatness ratio is 55% or less.

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