JP4900016B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire suitable for application to a tire having a low flatness ratio.

  A conventional pneumatic tire is composed of a tread portion, a shoulder portion, a sidewall portion, and a bead portion, and a carcass layer that forms a skeleton of the tire is disposed on the tread portion, and a belt layer is disposed on the outside of the carcass. A belt reinforcing layer is disposed outside. In addition, a bead core is formed in the bead portion by winding a bead wire, and a bead filler is disposed on the outer peripheral side of the bead core, and the end of the carcass extends from the inside to the outside of the tire around the bead core. It is folded and mounted.

  By the way, in such a pneumatic tire, for example, when the vehicle equipped with the pneumatic tire travels at a high speed, the vehicle stops in a state where the pneumatic tire generates heat, and a specific region of the pneumatic tire is long. A so-called flat spot may occur when the vehicle is in contact with the road surface for a period of time. That is, if the tire is stopped for a predetermined time in a state where the temperature is high due to high speed driving or the like, when the temperature of the tire decreases, the area where the tire contacts the road surface (the ground contact surface) is a vertical load such as the weight of the vehicle. The tire is deformed by the influence, and the rubber and organic fiber constituting the tire are deformed to generate residual strain in the tire. A flat spot is a flat part formed by this residual strain. When this flat spot is generated, the deformation is maintained for a while even when the vehicle starts to travel. This causes uneven shape in the circumferential direction of the tire. Stability may be reduced.

  Thus, for example, in the pneumatic radial tire described in Patent Document 1, the outer end position of the carcass folding portion is set on the outer peripheral side in the tire radial direction with respect to the tire maximum width position, and the outside of the bead apex (corresponding to a bead filler). The end position is set on the inner side in the tire radial direction from the maximum tire width position. As a result, the carcass turn-up portion and the bead apex outer end position are provided at a position apart from the maximum tire width position where the strain is likely to be greatly bent and strain is concentrated, thereby suppressing permanent strain accumulation in the portion. The occurrence of flat spots is suppressed.

JP 2006-321448 A

  However, in the pneumatic radial tire described in Patent Document 1, for example, the outer end position in the tire radial direction of a bead apex (corresponding to a bead filler) is provided on the outer side, or a steel reinforcing layer is provided around the bead core. In order to improve the handling stability by increasing the rigidity in the vicinity of the bead portion, the outer end portion of the bead apex located away from the bead core on the outer peripheral side in the tire radial direction because the rigidity around the bead core is increased. Local deformation tends to occur at. For this reason, the local deformation of the outer end portion of the bead apex deforms rubber and organic fibers constituting the tire and affects the flat spot resistance. As a result, the flat spot resistance may deteriorate. there were.

  Therefore, an object of the present invention is to provide a pneumatic tire that can improve flat spot resistance while maintaining steering stability.

  In order to achieve the above object, a pneumatic tire according to the invention of claim 1 is composed of at least one fiber cord selected from the group consisting of polyester fiber, rayon fiber, and highly elastic fiber, and a pair of bead cores in the tire radial direction. A carcass layer wound around the bead core around the bead core on the outer peripheral side from the inside in the tire width direction and spanned, and a high elastic fiber cord or a steel cord, and on the outer circumference in the tire radial direction of the carcass layer In a pneumatic tire having a belt layer provided and a belt reinforcing layer made of an organic fiber cord and provided on an outer periphery in the tire radial direction of the belt layer, the carcass layer and the bead filler include the tire incorporated in a regular rim. In the cross-sectional view in the tire meridian direction with the normal internal pressure corresponding to the normal load filled, The distance along the tire radial direction between the filler tip position on the outer periphery side of the tire in the tire radial direction and the carcass outermost position on the outer side in the tire width direction of the carcass line of the carcass layer is set in the range of 10 mm to 40 mm. A center reference point that is an intersection of an imaginary line parallel to the tire width direction from the filler tip position inward in the tire width direction and the carcass line, and the center reference point at the carcass line The radius of the carcass line setting curve passing through the outer peripheral side reference point and the inner peripheral side reference point located within a predetermined range set in advance with respect to the tire radial direction outer peripheral side and inner peripheral side is 0 of the tire radial height. It is characterized by being set in a range larger than 4 times and smaller than 0.7 times.

  In the pneumatic tire according to the invention of claim 2, the predetermined range is set by a virtual circle whose center is assumed to be the center reference point and whose radius is assumed to be 1/30 to 1/5 of the height in the tire radial direction. The outer circumferential side reference point and the inner circumferential side reference point are set by intersections of the virtual circle and the carcass line.

  In the pneumatic tire according to a third aspect of the present invention, the bead filler is made of a rubber composition having a retention rate of storage modulus measured at a temperature of 100 degrees with respect to the storage modulus measured at a temperature of 20 degrees of 60% or more. It is characterized by that.

  The pneumatic tire according to a fourth aspect of the present invention is characterized in that the organic fiber cord of the belt reinforcing layer is made of organic fibers having a glass transition temperature of 100 degrees or more and 75 weight percent or more and 90 weight percent or less. And

  The pneumatic tire according to the invention according to claim 5 is composed of at least one fiber cord selected from the group consisting of polyester fiber, rayon fiber, and highly elastic fiber provided at a predetermined angle with respect to the fiber cord of the carcass layer. A first side reinforcing belt having one end portion provided between the bead filler and the carcass layer on the inner side in the tire width direction and the other end portion provided on the inner side in the tire radial direction from the outermost position of the carcass; One end is provided between the carcass layer and the belt layer, and the other end is provided with a reinforcing layer having a second side reinforcing belt provided on the outer peripheral side in the tire radial direction from the outermost position of the carcass. And

  The pneumatic tire according to the invention according to claim 6 is characterized in that the reinforcing layer has the predetermined angle set in a range of 2 degrees to 40 degrees.

  In the pneumatic tire according to the invention according to claim 7, the reinforcing layer has a tire diameter between a tip position of the other end portion of the first side reinforcing belt and a tip position of the other end portion of the second side reinforcing belt. The distance between the directions is set in a range of 10 mm to 40 mm.

  The pneumatic tire according to an eighth aspect of the present invention is the pneumatic tire according to the invention, wherein the first side reinforcing belt has a distal end position of 5 mm from the filler proximal end position on the inner radial side of the bead filler to the outer peripheral side in the radial direction of the tire. It is set to the range of 10 mm or less.

  In the pneumatic tire according to the invention according to claim 9, in the first side reinforcing belt, the tip position of the other end portion is set in a range of 3 mm or more and 30 mm or less from the filler tip position toward the outer circumferential side in the tire radial direction. It is characterized by.

  In the pneumatic tire according to the invention according to claim 10, in the second side reinforcing belt, the amount of intrusion in the tire width direction between the carcass layer and the belt layer at the tip position of the one end is 5 mm or more. It is characterized by being set to.

  The pneumatic tire according to the invention according to claim 11 is characterized in that the flatness is 50% or less.

  According to the pneumatic tire of the invention according to claim 1, by providing the filler tip position at a position away from the outermost position of the carcass where the strain is likely to be largely bent and strain is concentrated when a load is applied, Accumulation of permanent residual strain (permanent strain) near the filler tip position is suppressed. Furthermore, by setting the carcass line and the bead filler to be close to a straight line by reducing the curvature of the carcass line in the vicinity of the filler tip position, the carcass layer and the tip of the bead filler are in direct contact with each other. become. For this reason, the local deformation | transformation including the front-end | tip part of the bead filler which has a big influence with respect to flat spot resistance when a load acts is further suppressed. Thereby, the permanent set set during the thermal cooling of the pneumatic tire can be reduced, and the occurrence of flat spots can be reliably suppressed. In addition, since the tip of the bead filler is not easily affected by the deformation of the carcass layer, the shape is less dependent on load, the steering stability is improved, and the length of the bead filler toward the outer periphery in the tire radial direction is increased. Even if the rigidity around the bead core is increased, local deformation in the vicinity of the filler tip located away from the bead core on the outer side in the tire radial direction is suppressed. Steering stability can also be ensured. As a result, it is possible to improve flat spot resistance while maintaining steering stability.

  According to the pneumatic tire of the invention according to claim 2, the virtual circle that sets the predetermined range has a center as a center reference point and a radius of [tire height in the tire radial direction / 30] ≦ radius ≦ [height in the tire radial direction. / 5] prevents the local deformation including the tip portion of the bead filler from being able to exert its effect of reducing the curvature of the carcass line in the vicinity of the filler tip position. In addition, the range in which the curvature is reduced is too wide, and it is possible to prevent the proper shape as a pneumatic tire from being destroyed.

  According to the pneumatic tire of the invention according to claim 3, by constituting the bead filler with a rubber composition having a low temperature dependency of the storage elastic modulus, the amount of deformation accompanying a temperature change in the bead filler is reduced. The accumulation of permanent residual strain (permanent strain) is suppressed, and the permanent strain set during thermal cooling can be reduced as a result, and the flat spot occurrence rate can be further reduced.

  According to the pneumatic tire of the invention according to claim 4, the amount of organic fibers having a glass transition temperature of less than 100 degrees is too large, and permanent residual strain (permanent strain) is likely to be accumulated in the belt reinforcing layer. The flat spot resistance can be prevented from deteriorating, and the amount of high-rigid organic fibers having a glass transition temperature of 100 ° C. or higher is too large to be easily extended with respect to the tensile force. It is possible to prevent the pneumatic tire from becoming a predetermined shape at the time of molding the tire, and to prevent the durability against load deformation from deteriorating.

  According to the pneumatic tire of the invention according to claim 5, the first side reinforcing belt is provided on the inner side in the tire radial direction across the outermost position of the carcass, and the second side reinforcing belt is provided on the outer side in the tire radial direction. By providing the first side reinforcing belt, the deformation of the bead filler can be suppressed, the accumulation of permanent residual strain (permanent strain) near the filler tip position of the bead filler can be suppressed, and the second side The rigidity in the tire circumferential direction can be increased by the reinforcing belt, and thus the steering stability can be improved. In addition, since the reinforcement layer is not provided in the vicinity of the carcass outermost position where the strain is likely to be greatly bent and concentrated when a load is applied, the vicinity of the carcass outermost position M is actively deformed. Since the load can be absorbed, the amount of tire deformation on the inner side in the tire radial direction and on the outer side in the tire radial direction other than the vicinity of the carcass outermost position can be further reduced. In addition, the first side reinforcing belt and the second side reinforcing belt are prevented from being deformed together with the deformation of the carcass layer at the carcass outermost position. As a result, the bead filler is deformed together. Is also prevented. For this reason, the filler tip of the bead filler is not easily affected by the deformation of the carcass layer at the outermost position of the carcass, so that the structure is less dependent on the load, thereby improving the steering stability and the flat spot resistance. Can be improved.

  According to the pneumatic tire of the invention of claim 6, the fiber cords of the first side reinforcing belt and the second side reinforcing belt are 2 ° ≦ [the angle formed by the fiber cord of the reinforcing layer and the fiber cord of the carcass layer]. Since the angle is set so as to be ≦ 40 °, it is possible to prevent the angle from being too small to exhibit an appropriate reinforcing effect, and the angle is too large to reduce the rigidity in the tire circumferential direction. It can prevent that the effect which suppresses distortion falls.

  According to the pneumatic tire of the invention of claim 7, the first side reinforcing belt and the second side reinforcing belt have a distance of 10 [mm] ≦ [distance between the tip positions of the other end portions in the tire radial direction] ≦ Since it is provided to be 40 [mm], it is possible to prevent the first side reinforcing belt and the second side reinforcing belt from being affected by deformation of the carcass layer at the outermost position of the carcass because the distance is too narrow. can do. For this reason, it can prevent that the filler front-end | tip part of a bead filler receives the influence of a deformation | transformation of the carcass layer in a carcass outermost position, and the said space | interval is too wide and the 1st side reinforcement belt and the 2nd side It can prevent that the reinforcement area by a reinforcement belt becomes small and a reinforcement effect falls.

  According to the pneumatic tire of the invention according to claim 8, the first side reinforcing belt has an interval between the tip position of one end and the filler base end position of 5 [mm] ≦ [tip position of one end and filler base. Since the distance between the end positions] ≦ 10 [mm], the distance is too narrow, and for example, the local strain of the rubber member between the bead wire forming the bead core and the end portion of the reinforcing layer is increased. In addition, it is possible to prevent the first side reinforcing belt from being deformed due to the load because the interval is too wide and one end portion is separated from the rigid bead core. The effect of the reinforcing layer can be sufficiently exhibited.

  According to the pneumatic tire of the invention according to claim 9, the first side reinforcing belt has a distance between the tip position of the other end and the filler tip position of 3 [mm] ≦ [tip position of the other end and filler. Since it is provided so that the distance from the tip position] ≦ 30 [mm], it is possible to prevent the gap from being too narrow to suppress the deformation of the filler tip of the bead filler and to prevent distortion at the filler end. Concentration, and the distance between the other ends is too close to the carcass outermost position, and the influence of the deformation of the carcass layer at the carcass outermost position is prevented. Can be prevented.

  According to the pneumatic tire of the invention according to claim 10, the tip position of the one end portion of the second side reinforcing belt is such that the amount of penetration between the carcass layer and the belt layer is 5 [mm] ≦ [carcass layer and The amount of penetration into the belt layer] ≦ 50 [mm] is provided, so that the penetration amount is too small to increase the tire circumferential rigidity and improve steering stability. It is possible to prevent the second side reinforcing belt from excessively increasing due to the amount of penetration being too large.

  According to the pneumatic tire according to the eleventh aspect of the present invention, the present invention is applied to a pneumatic tire with a flatness ratio of 50% or less that is relatively long in the tire width direction, so that steering stability is more significantly maintained. There is an advantage that the effect of improving the flat spot resistance can be achieved.

  Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

(Embodiment 1)
FIG. 1 is a meridional partial cross-sectional view including an equatorial plane of a pneumatic tire according to Embodiment 1 of the present invention, and FIG. 2 is a meridional partial cross-sectional view illustrating a main part of the pneumatic tire according to Embodiment 1 of the present invention. is there.

  As shown in FIG. 1, the pneumatic tire 1 is configured to be substantially symmetric with respect to the equator plane 50. Here, the equatorial plane 50 is a plane that is orthogonal to the rotation axis and passes through the center of the width of the pneumatic tire 1. In the following description, the pneumatic tire 1 is configured so as to be substantially symmetric with respect to the equator plane 50. Therefore, FIG. As long as there is not, only the said one side is demonstrated and description of the other side is abbreviate | omitted as much as possible.

  In the following description, the tire width direction means a direction parallel to the rotation axis of the pneumatic tire, the tire radial direction means a direction perpendicular to the rotation axis, and the tire circumferential direction (see FIG. 1). The term “rotation direction” refers to a direction of rotation with the rotation axis serving as a rotation axis. Further, the inner side in the tire width direction refers to a direction toward the equator plane 50 in the tire width direction, and the outer side in the tire width direction refers to a direction away from the equator plane 50 in the tire width direction.

  As shown in FIG. 1, the pneumatic tire 1 includes a tread portion 6 having a tread surface 5, left and right shoulder portions 7 continuous on both sides thereof, sidewall portions 8, and bead portions 9. . The pneumatic tire 1 further includes a carcass layer 10, a belt layer 11, a belt reinforcing layer 12, an inner liner 13, and a bead core 14.

  The tread surface 5 is provided with a tread groove 5a and a land portion 5b defined by the tread groove 5a. The tread groove 5a has a main groove formed continuously in the tire circumferential direction and a plurality of lug grooves (not shown) extending in the tire width direction. On the tread surface 5, a tread pattern is formed by the tread groove 5a and the land portion 5b.

  The carcass layer 10 includes a carcass ply 10a formed of a carcass cord covered with rubber, and forms a tire skeleton. The carcass ply 10 a extends from both sides of the tread portion 6 to the bead portion 9 via the left and right shoulder portions 7 and the sidewall portions 8 with the equator plane 50 as the center. Further, the carcass cords of the carcass ply 10a are arranged at an angle of approximately 90 degrees with respect to the tire circumferential direction. The carcass ply 10a is a strength member that functions as a pressure vessel when the pneumatic tire 1 is filled with air. The carcass ply 10a has a structure that supports the load by its internal pressure and withstands a dynamic load during traveling. ing.

  Here, in the carcass layer 10, the carcass cord of the carcass ply 10 a is made of at least one fiber cord selected from the group consisting of polyester fiber, rayon fiber, and highly elastic fiber. The polyester fiber is a fiber composed of a long chain synthetic polymer mainly composed of ester bonds (—CO · O—) in the monomer mutual bond. For example, polyethylene terephthalate fiber or PEN (polyethylene naphthalate fiber) is used. That's fine. The rayon fiber is preferably, for example, a strong viscose rayon, but is not limited thereto. The highly elastic fiber is, for example, a fiber having a higher elastic modulus than nylon, and a fiber such as aramid or aromatic polyamide may be used.

  The belt layer 11 is a layer that is attached in the tire circumferential direction and reinforces the carcass layer 10. The belt layer 11 is disposed on the outer circumferential side of the carcass layer 10 in the tire radial direction. The belt layer 11 includes, in order from the inner side in the tire radial direction, a first belt 11a and a second belt 11b formed by a belt cord covered with rubber. The first belt 11a and the second belt 11b are formed so that their belt cords cross each other, and are formed as so-called cross-ply belts. The belt layer 11 tightens the carcass layer 10 to increase the tread rigidity, and relaxes the impact to prevent trauma generated on the tread from reaching the carcass layer 10.

  Here, in the belt layer 11, the belt cords of the first belt 11a and the second belt 11b are made of a highly elastic fiber cord or a steel cord. The highly elastic fiber is, for example, a fiber having a higher elastic modulus than nylon, and a fiber such as aramid or aromatic polyamide may be used. As the steel cord, for example, one or a plurality of steel filaments having a strand diameter of 0.1 mm to 0.4 mm may be used.

  The belt reinforcing layer 12 is a layer for further reinforcing the belt layer 11. The belt reinforcing layer 12 is provided between the tread surface 5 that is the surface of the tread portion 6 and the belt layer 11. That is, the belt reinforcing layer 12 is disposed on the inner side in the tire radial direction of the tread surface 5 and on the outer side in the tire radial direction of the belt layer 11. The belt reinforcing layer 12 includes a first reinforcing belt 12a and a second reinforcing belt 12b formed by reinforcing belt cords covered with rubber in order from the inside in the tire radial direction. The tread surface 5 of the tread portion 6 described above is formed on the outer peripheral side of the belt reinforcing layer 12 in the tire radial direction. Each of the first reinforcing belt 12a and the second reinforcing belt 12b has a reinforcing belt cord arranged in the tire circumferential direction. The belt reinforcing layer 12 reinforces the belt layer 11 to suppress the generation of vibration during rolling of the tire to reduce road noise at the mid-frequency, and to rise the end of the belt layer 11 Etc. to improve the tire's high-speed durability and high-speed stability. The reinforcing belt cords of the first reinforcing belt 12a and the second reinforcing belt 12b will be described in detail later.

  The bead core 14 supports the cord tension of the carcass layer 10 generated by the internal pressure of the pneumatic tire 1 at the bead portion 9. The pair of left and right bead cores 14 includes a plurality of bead wires, and the bead wires are configured by steel wires as high-rigidity materials. The pair of bead cores 14 is formed by continuously winding the bead wire to form a ring shape. The bead core 14 serves to fix the pneumatic tire 1 to a wheel rim (not shown), and also functions as a strength member of the pneumatic tire 1 together with the carcass layer 10, the belt layer 11, the belt reinforcing layer 12, and the like. .

  In the carcass layer 10, the carcass ply 10 a is folded outward from the equatorial plane 50 side of the pneumatic tire 1 around the bead core 14, and the bead filler 15 is filled in the space between the carcass layer 10 and the bead core 14. As a result, the bead portion 9 is configured. More specifically, the carcass ply 10a has a carcass main body portion 10b and a folded portion 10c. The carcass main body portion 10 b extends between the pair of left and right bead cores 14. A pair of left and right folded portions 10c are provided corresponding to the pair of right and left bead cores 14, and are wound around the bead cores 14 from both ends of the carcass main body portion 10b so as to extend outward in the tire radial direction.

  That is, the carcass ply 10a is spanned between a pair of bead cores 14 symmetrically with respect to the equator plane 50, extends from the tread portion 6 to the bead portion 9 via the sidewall portion 8, and further the bead filler 15 is The bead core 14 is wound up so as to wrap outward from the equatorial plane 50 side. The bead filler 15 is filled in a space defined by the bead core 14, the carcass main body portion 10 b, and the turned-up portion 10 c on the outer circumferential side of the bead core 14 in the tire radial direction, so that the carcass ply 10 a of the carcass layer 10 becomes the bead core 14. While fixing, the shape of this part is adjusted and the rigidity of the whole bead part 9 is improved. An inner liner 13 is formed along the carcass layer 10 inside the carcass layer 10.

  When the pneumatic tire 1 configured as described above is mounted on a vehicle and travels, the pneumatic tire 1 rotates while the tread surface 5 is in contact with a road surface (not shown). At this time, a large load acts on the tread surface 5 in the pneumatic tire 1. Here, the pneumatic tire 1 of the present embodiment is configured as a pneumatic tire 1 having a flatness ratio of 50% or less. As shown in FIG. 1, the flatness ratio represents the tire height SH with respect to the tire width W as a ratio. When the flatness of the pneumatic tire 1 is reduced, the thickness of the pneumatic tire 1 when viewed from the side is reduced, and the width of the tread surface 5 is increased. Accordingly, the belt layer 11 and the belt reinforcing layer 12 are increased. The width of is also widened. Thereby, since tread bending rigidity becomes large, a cornering force improves and steering stability can be improved.

  By the way, in such a pneumatic tire 1, for example, when the vehicle equipped with the pneumatic tire 1 travels at high speed, the vehicle stops in a state where the pneumatic tire 1 generates heat, and the pneumatic tire 1 is specified. When such a region is in contact with the road surface for a long period of time, a so-called flat spot may be generated. That is, when the pneumatic tire 1 is stopped for a predetermined time in a state where the temperature of the pneumatic tire 1 is high due to high speed traveling or the like, when the temperature of the tire decreases, a region where the pneumatic tire 1 contacts the road surface (a ground contact surface) The tire may be deformed by the influence of a vertical load such as weight, and the rubber or fiber cord constituting the pneumatic tire 1 may be deformed to cause residual strain in the tire. The flat spot is a flat portion formed by the residual strain. When the flat spot is generated, the deformation is maintained for a while even when the running is started. Since non-uniform shapes occur, there is a risk that vibration will occur during traveling and steering stability will be reduced.

  On the other hand, in order to improve the steering stability, for example, by providing the filler tip position on the outer side in the tire radial direction of the bead filler on the outer side, or by providing a steel reinforcing layer etc. around the bead core, When the rigidity in the vicinity of the bead is increased, the tip of the bead filler is located away from the bead core on the outer side in the tire radial direction because the filler tip position is provided on the outer side or the rigidity around the bead core is increased. Local deformation tends to occur at. For this reason, the local deformation of the tip of the bead filler deforms the rubber and organic fibers constituting the tire and affects the flat spot resistance. As a result, the flat spot resistance may be deteriorated. .

  Therefore, in the pneumatic tire 1 of the present embodiment, as shown in FIGS. 1 and 2, the tip position of the bead filler 15 and the carcass line curvature of the carcass ply 10a in the vicinity thereof are appropriately set to stabilize the operation. The flat spot resistance is improved while maintaining the properties.

  In the following description, unless otherwise specified, the positional relationship between the respective parts is a state in which the pneumatic tire 1 is incorporated in a normal rim and filled with a normal internal pressure corresponding to a normal load in a sectional view in the tire meridian direction. It will be described as defined in. 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 the “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.

  The carcass ply 10a and the bead filler 15 of the carcass layer 10 are, as shown in FIG. 2, the filler tip position 15a on the tire radial direction outer peripheral side of the bead filler 15 and the outer side in the tire width direction of the carcass line 10d of the carcass ply 10a. A distance L1 along the tire radial direction from the carcass outermost position M on the side is set within a predetermined range. Here, the carcass line 10 d is a line passing through the center of the cross-sectional thickness of the innermost carcass ply 10 a in the carcass layer 10. Therefore, by providing the filler tip position 15a at a position away from the carcass outermost position M where the strain is likely to be greatly bent and strain is concentrated when a load is applied, the bead filler 15 has a permanent vicinity in the vicinity of the filler tip position 15a. Accumulation of residual strain (permanent strain) is suppressed. And the permanent distortion set during the heat cooling at the time of the stop of the pneumatic tire 1 can also be reduced as a result, and generation | occurrence | production of a flat spot is suppressed accordingly. In addition, since the filler tip of the bead filler 15 is not easily affected by the deformation of the carcass ply 10a at the carcass outermost position M, the shape is less dependent on the load, and as a result, steering stability is improved.

  Specifically, the distance L1 between the carcass ply 10a and the bead filler 15 is set in a range of 10 mm or more and 40 mm or less. That is, the carcass ply 10a and the bead filler 15 are provided so as to satisfy 10 [mm] ≦ L1 ≦ 40 [mm]. Thereby, since the distance L1 along the tire radial direction between the filler front end position 15a and the carcass outermost position M is larger than 10 [mm], the distance L1 is too narrow and the filler front end of the bead filler 15 becomes the carcass. It is possible to prevent the influence of deformation near the outermost position M. On the other hand, since the interval L1 is narrower than 40 [mm], the interval L1 is too wide, in other words, the length of the bead filler 15 on the outer side in the tire radial direction is too short, and the rigidity around the bead core 14 is sufficiently secured. It is possible to prevent the steering stability from being lowered.

  Further, the carcass ply 10a and the bead filler 15 are set so that the curvature of the carcass line 10d is reduced and close to a straight line in the vicinity of the filler tip position 15a, so that the tip of the carcass ply 10a and the bead filler 15 Are brought into linear contact with each other, whereby the deformation of the contact portion between the carcass ply 10a and the bead filler 15 is reduced, and the local deformation including the tip of the bead filler 15 is suppressed.

  Specifically, the positional relationship between the carcass ply 10a and the bead filler 15 is set as follows. That is, as shown in FIG. 2, an imaginary line A is set in parallel to the tire width direction from the filler tip position 15a inward in the tire width direction, and the intersection of the imaginary line A and the carcass line 10d is a central reference. Let it be point CO.

  Next, on the carcass line 10d, an outer peripheral side reference point CA and an inner peripheral side reference point CB located within a predetermined range set in advance from the center reference point CO to the tire radial direction outer peripheral side and inner peripheral side. Set. Specifically, this predetermined range is set by a virtual circle B. The virtual circle B is a circle whose center is set to the center reference point CO and whose radius R1 is set to 1/30 to 1/5 of the tire height SH (see FIG. 1) in the tire radial direction. That is, the virtual circle B is set so that SH / 30 ≦ R1 ≦ SH / 5 with the center reference point CO as the center, and the outer peripheral side reference point CA and the inner peripheral side reference point CB are the same as the virtual circle B. It is set as an intersection with the carcass line 10d. Here, the tire height SH is along the tire radial direction from the tire radial inner peripheral side end portion (that is, the rim base position) of the bead portion 9 to the center crown that is the intersection of the equatorial plane 50 and the tread surface 5. This is the tire cross-section height.

  Here, the predetermined range set by the virtual circle B corresponds to a range in which the curvature of the carcass line 10d is reduced in the vicinity of the filler tip position 15a. That is, a range in which the curvature of the carcass line 10d is reduced in the vicinity of the filler tip position 15a by setting the virtual circle B so that the center is the center reference point CO and the radius R1 is SH / 30 ≦ R1 ≦ SH / 5. Is wider than the range from the filler tip position 15a to SH / 30, it can be prevented that the range is too small and the effect of suppressing local deformation including the tip of the bead filler 15 cannot be exhibited. On the other hand, since the range in which the curvature is reduced is narrower than the range from the filler tip position 15a to SH / 5, it is possible to prevent the range from being too wide and the proper shape as the pneumatic tire 1 from collapsing. .

  Next, a carcass line setting curve C passing through the three points of the center reference point CO, the outer peripheral side reference point CA, and the inner peripheral side reference point CB specified on the carcass line 10d is set. In the carcass line setting curve C, the radius R2 is set in a range larger than 0.4 times and smaller than 0.7 times the tire height SH. That is, the positional relationship between the carcass line 10d and the filler tip position 15a is set so that the carcass ply 10a and the bead filler 15 satisfy SH × 0.4 <R2 <SH × 0.7. Since the radius R2 of the carcass line setting curve C is larger than SH × 0.4, it is possible to prevent the radius R2 from being too small and increase the curvature of the carcass line 10d in the vicinity of the filler tip position 15a. The contact state between the ply 10a and the tip of the bead filler 15 can be properly maintained as a linear contact. On the other hand, since the radius R2 of the carcass line setting curve C is smaller than SH × 0.7, it is possible to prevent the appropriate shape as the pneumatic tire 1 from collapsing due to the radius R2 being too large.

  In the pneumatic tire 1 configured as described above, by setting the carcass ply 10a and the bead filler 15 in the vicinity of the filler tip position 15a so as to reduce the curvature of the carcass line 10d and be close to a straight line, The carcass ply 10a and the tip of the bead filler 15 come into linear contact. For this reason, when the load is applied, the deformation of the contact portion between the carcass ply 10a and the tip of the bead filler 15 can be reduced, and the tip of the bead filler 15 having a great influence on the flat spot resistance is included. Local deformation is suppressed. And since the local deformation | transformation of the front-end | tip part of this bead filler 15 is suppressed, accumulation | storage of the permanent residual strain (permanent strain) in the filler front-end | tip position 15a vicinity of the bead filler 15 is suppressed. As a result, permanent distortion set during thermal cooling when the pneumatic tire 1 is stopped can be further reduced, and generation of flat spots is thus reliably suppressed. Further, for example, even if the length of the bead filler 15 on the outer periphery side in the tire radial direction is increased and the rigidity around the bead core 14 is increased, the vicinity of the filler tip position 15a located away from the bead core 14 on the outer peripheral side in the tire radial direction. Since local deformation is suppressed, the flat spot resistance can be improved and sufficient steering stability can be ensured.

Here, in the pneumatic tire 1 of this embodiment, the bead filler 15, the retention of the storage modulus E ₁₀₀ was measured at a temperature of 100 ° relative to the storage modulus E ₂₀ measured at a temperature 20 ° is 60% or more It consists of a rubber composition. Here, the storage elastic modulus is a parameter indicating the characteristics of rubber, and is a measure of energy stored by strain. Here, the storage elastic modulus E ₂₀ and the storage elastic modulus E ₁₀₀ were measured at a static strain of 1%, a dynamic strain of 0.5%, and a frequency of 20 Hz using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho. The rubber composition satisfying E ₁₀₀ / E ₂₀ × 100 ≧ 60% is used as the bead filler 15. The bead filler 15 is made of, for example, a high cis butadiene rubber (BR) and a high crystalline syndiotactic polybutadiene polymer rubber (VCR; vinyl cis butadiene rubber), and the like, to reduce the content of the resin component and the plasticizer. It is obtained by.

For example, as the temperature of the pneumatic tire 1 increases during traveling, the temperature of the bead filler 15 also increases (for example, 100 ° C.), so that the bead filler 15 becomes soft and deforms. Thereafter, when the pneumatic tire 1 is stopped and cooled and the bead filler 15 is hardened (for example, 20 ° C.), if the difference in storage elastic modulus between the high temperature and the low temperature is large, the strain amount of the bead filler 15 is increased. Although there is a possibility that the amount of deformation increases and the amount of deformation increases, as in this embodiment, the bead filler 15 is a rubber composition that satisfies E ₁₀₀ / E ₂₀ × 100 ≧ 60%, in other words, the storage elastic modulus. By using a rubber composition having low temperature dependence, the amount of deformation accompanying a temperature change from high temperature to low temperature (for example, 100 → 20 ° C.) is reduced, so that permanent residual strain in the bead filler 15 (permanent strain) ) Is suppressed. And the permanent set set during the thermal cooling at the time of the stop of the pneumatic tire 1 can also be reduced as a result, and the incidence rate of a flat spot can be further lowered.

Further, in the belt reinforcement layer 12, the reinforcement belt cords of the first reinforcement belt 12a and the second reinforcement belt 12b are made of organic fiber cords having a glass transition temperature _Tg of 100 degrees or more of 75 weight percent or more and 90 weight percent or less. Composed. That is, the reinforcing belt cords of 1st reinforcing belt 12a, 2 No. reinforcing belt 12b is 75 wt% or more and 90% by weight or less, made of an organic fiber cord having a glass transition temperature T _g of more than 100 degrees. Here, the glass transition temperature _Tg is, for example, a phenomenon that changes from a glassy hard state to a rubbery state when a polymer substance is heated, that is, a temperature at which the glass transition occurs. It can exert a proper performance at a temperature below T _g temperature. Examples of organic fibers having a glass transition temperature _Tg of 100 ° C. or higher include polyethylene naphthalate fibers, rayon fibers, aramid fibers, polyparaphenylene benzbisoxazole fibers, and the like. Here, for example, one twist of a single twisted cord of aramid fiber 1670 [dtex (fineness; unit representing the weight of yarn per 1000 m)] and a single twisted cord of nylon fiber 940 [dtex] A cord (1670/2 Aramid 940 Nylon) is made, and the reinforced belt cords of the first reinforcing belt 12a and the second reinforcing belt 12b are formed by the twisted cord.

That is, more than one number 75 wt% of the reinforcing belt cords of the reinforcing belt 12a, 2 No. reinforcing belt 12b, the glass transition temperature T _g is composed of organic fiber cords of more than 100 degrees, for example, a glass transition temperature T _g The amount of organic fibers (for example, normal nylon fibers) of less than 100 degrees is too large, and permanent residual strain (permanent strain) is likely to be accumulated in the belt reinforcing layer 12. It is possible to prevent the spot property from deteriorating. On the other hand, since 90 weight percent or less of the reinforcing belt cord is composed of an organic fiber cord having a glass transition temperature _Tg of 100 degrees or more, for example, the amount of organic fibers having a glass transition temperature _Tg of less than 100 degrees is too small. In other words, it is prevented that the amount of the high-rigid organic fiber having a glass transition temperature _Tg of 100 ° C. or more is too large to be easily extended with respect to the tensile force, and the pneumatic tire does not have a predetermined shape when the tire is molded. This can be prevented, and the durability against load deformation can be prevented from deteriorating.

  According to the pneumatic tire 1 according to the present embodiment described above, the tire includes at least one fiber cord selected from the group consisting of polyester fiber, rayon fiber, and highly elastic fiber, and a pair of bead cores 14 in the tire radial direction outer peripheral side. The carcass layer 10 is wound around the bead core 14 from the inside in the tire width direction through the bead filler 15 and the outer circumference in the tire radial direction of the carcass layer 10 made of a highly elastic fiber cord or steel cord. In the pneumatic tire 1 having the belt layer 11 provided on the belt and the belt reinforcing layer 12 made of an organic fiber cord and provided on the outer periphery in the tire radial direction of the belt layer 11, the carcass layer 10 and the bead filler 15 Cross-sectional view in the tire meridian direction with a normal internal pressure corresponding to the normal load installed in the rim The distance L1 along the tire radial direction between the filler tip position 15a on the tire radial direction outer peripheral side of the bead filler and the carcass outermost position M on the outer side in the tire width direction of the carcass line 10d of the carcass layer 10 Is set in a range of 10 mm or more and 40 mm or less, and a center reference point CO that is an intersection of a virtual line A and a carcass line 10d that is virtually in parallel to the tire width direction from the filler tip position 15a inward in the tire width direction; In the carcass line 10d, the carcass passes from the center reference point CO to the outer peripheral side reference point CA and the inner peripheral side reference point CB which are located within a predetermined range set in advance in the tire radial direction outer peripheral side and inner peripheral side. The radius R2 of the line setting curve C is set in a range larger than 0.4 times the tire radial height and smaller than 0.7 times.

  Therefore, by providing the filler tip position 15a at a position away from the carcass outermost position M where the strain is likely to be greatly bent and strain is concentrated when a load is applied, the bead filler 15 has a permanent vicinity in the vicinity of the filler tip position 15a. Accumulation of residual strain (permanent strain) is suppressed. Further, by setting the carcass ply 10a and the bead filler 15 in the vicinity of the filler tip position 15a so as to reduce the curvature of the carcass line 10d and be close to a straight line, Comes to touch in a straight line. For this reason, when the load is applied, the deformation of the contact portion between the carcass ply 10a and the tip of the bead filler 15 can be reduced, and the tip of the bead filler 15 having a great influence on the flat spot resistance is included. Local deformation is suppressed. For this reason, the permanent distortion set during the thermal cooling of the pneumatic tire 1 can be reduced, and generation | occurrence | production of a flat spot can be suppressed reliably. In addition, since the tip of the filler of the bead filler 15 is not easily affected by the deformation of the carcass ply 10a at the carcass outermost position M, the shape is less dependent on the load, the steering stability is improved, and the tire of the bead filler 15 is improved. Even if the length toward the radially outer periphery is increased and the rigidity around the bead core 14 is increased, local deformation in the vicinity of the filler tip position 15a located away from the bead core 14 toward the outer periphery in the tire radial direction is suppressed. As a result, the flat spot resistance can be improved and sufficient steering stability can be secured. As a result, it is possible to improve flat spot resistance while maintaining steering stability.

  Furthermore, according to the pneumatic tire 1 according to the present embodiment described above, the predetermined range is such that the center is the center reference point CO and the radius R2 is 1/30 to 1/5 of the tire radial height SH. The outer circle side reference point CA and the inner circle side reference point CB are set by the intersection of the virtual circle B and the carcass line 10d. Therefore, by setting the virtual circle B that sets the predetermined range so that the center is the center reference point CO and the radius R1 is SH / 30 ≦ R1 ≦ SH / 5, the carcass line near the filler tip position 15a. It is possible to prevent the range of reducing the curvature of 10d from being too small to exert the effect of suppressing local deformation including the tip of the bead filler 15, and the range of reducing the curvature is too wide to enter the air. It can prevent that the proper shape as the tire 1 collapses.

Furthermore, according to the pneumatic tire 1 according to the present embodiment described above, the bead filler 15, the retention of the storage modulus E ₁₀₀ was measured at a temperature of 100 ° relative to the storage modulus E ₂₀ measured at a temperature 20 ° Is made of a rubber composition having 60% or more. Therefore, by forming the bead filler 15 with a rubber composition having a low temperature dependency of the storage elastic modulus satisfying E ₁₀₀ / E ₂₀ × 100 ≧ 60%, the deformation amount associated with the temperature change in the bead filler 15 is reduced. Therefore, accumulation of permanent residual strain (permanent strain) is suppressed, and permanent strain set during thermal cooling when the pneumatic tire 1 is stopped can be reduced as a result. The incidence can be further reduced.

Furthermore, according to the pneumatic tire 1 according to the present embodiment described above, the reinforcing belt cord (organic fiber cord) of the belt reinforcing layer 12 has a glass transition temperature of 100 degrees with a weight ratio of 75 to 90 weight percent. It is comprised with the above organic fiber. Therefore, for example, the amount of organic fibers having a glass transition temperature _Tg of less than 100 degrees is excessive, and it is possible to suppress the permanent residual strain (permanent strain) from being easily accumulated in the belt reinforcing layer 12. The flat spot resistance can be prevented from deteriorating, and the amount of high-rigid organic fibers having a glass transition temperature _Tg of 100 ° C. or more is prevented from being excessively increased with respect to the tensile force. It is possible to prevent the pneumatic tire from becoming a predetermined shape at the time of molding the tire, and to prevent the durability against load deformation from deteriorating.

  Furthermore, according to the pneumatic tire 1 which concerns on this embodiment demonstrated above, a flat rate is 50% or less. Therefore, by applying the configuration described above to a pneumatic tire having a relatively long flatness of 50% or less in the tire width direction, the effect of improving the flat spot resistance while maintaining the steering stability more remarkably can be obtained. There is an advantage that it can be played.

(Embodiment 2)
FIG. 3 is a meridional partial cross-sectional view including the equatorial plane of a pneumatic tire according to Embodiment 2 of the present invention, and FIG. 4 shows the carcass layer and the split side reinforcing layer of the pneumatic tire according to Embodiment 2 of the present invention. It is a top view which shows a laminated structure. The pneumatic tire according to the second embodiment has substantially the same configuration as the pneumatic tire according to the first embodiment, but further includes a split side reinforcing layer as a reinforcing layer, and the pneumatic tire according to the first embodiment. Is different. In addition, about the structure, effect | action, and effect which are common in embodiment mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  As shown in FIG. 3, the pneumatic tire 201 according to the second embodiment further includes a divided side reinforcing layer 220 as a reinforcing layer. The divided side reinforcing layer 220 includes a first side reinforcing belt 221 and a second side reinforcing belt 222.

  The first side reinforcing belt 221 has one end 221a provided between the bead filler 15 and the carcass layer 10 in the tire width direction, that is, the carcass main body 10b of the carcass ply 10a, and the other end 221b is the carcass outermost portion. It is provided on the inner peripheral side in the tire radial direction from the outer position M. On the other hand, the second side reinforcing belt 222 has one end portion 222a provided between the carcass layer 10 and the belt layer 11, that is, between the carcass main body portion 10b of the carcass ply 10a and the first belt 11a of the belt layer 11. The other end 222b is provided on the outer circumferential side in the tire radial direction from the carcass outermost position M. Therefore, in the divided side reinforcing layer 220, the first side reinforcing belt 221 is provided on the inner side in the tire radial direction with the carcass outermost position M in between, and the second side reinforcing belt 222 on the outer side in the tire radial direction. The first side reinforcing belt 221 and the second side reinforcing belt 222 are spaced apart in the tire radial direction L2 in the vicinity of the carcass outermost position M where the distortion tends to concentrate due to large bending when a load is applied. It is provided with a gap.

  Further, the first side reinforcing belt 221 and the second side reinforcing belt 222 of the divided side reinforcing layer 220 are formed of side reinforcing belt cords covered with rubber. The side reinforcing belt cords of the first side reinforcing belt 221 and the second side reinforcing belt 222 are at least one fiber cord selected from the group consisting of polyester fiber, rayon fiber, and highly elastic fiber, like the carcass cord of the carcass ply 10a. Consists of. Further, here, the side reinforcing belt cords of the first side reinforcing belt 221 and the second side reinforcing belt 222 are provided at a predetermined angle with respect to the carcass cord of the carcass ply 10a.

  Specifically, as shown in FIG. 4, the carcass ply 10a is formed by covering a plurality of carcass cords 10A with a base material 10B (coating rubber or the like). As described above, the carcass cord 10A of the carcass ply 10a is arranged at an angle of approximately 90 degrees with respect to the tire circumferential direction.

  On the other hand, the first side reinforcing belt 221 and the second side reinforcing belt 222 are formed by covering a plurality of side reinforcing belt cords 221A and 222A with base materials 221B and 222B (coating rubber or the like), respectively. The side reinforcing belt cords 221A and 222A of the first side reinforcing belt 221 and the second side reinforcing belt 222 are provided with a predetermined angle θ with respect to the carcass cord 10A of the carcass ply 10a. Here, the predetermined angle θ is preferably set in a range of 2 degrees to 40 degrees. Here, the predetermined angle θ is an acute angle with respect to the carcass cord 10A.

  The pneumatic tire 201 configured as described above is provided with the first side reinforcing belt 221 on the inner side in the tire radial direction across the carcass outermost position M, and the second side reinforcement on the outer side in the tire radial direction. By providing the belt 222, it is possible to suppress the deformation of the bead filler 15 by the first side reinforcing belt 221 and suppress the accumulation of permanent residual strain (permanent strain) in the vicinity of the filler tip position 15a of the bead filler 15. At the same time, the rigidity in the tire circumferential direction can be increased by the second side reinforcing belt 222, and thus the steering stability can be improved.

  In the vicinity of the carcass outermost position M, the first side reinforcing belt 221 and the second side reinforcing belt 222 are provided with a gap L2 in the tire radial direction, and are greatly bent and strained when a load is applied. Since the split side reinforcing layer 220 is not provided in the vicinity of the carcass outermost position M where it is easy to concentrate, the vicinity of the carcass outermost position M can be positively deformed to absorb the load. The amount of deformation of the carcass ply 10a and the like on the inner side in the tire radial direction and the outer peripheral side in the tire radial direction other than the vicinity of the outermost position M can be further reduced. That is, the first side reinforcing belt 221 and the second side reinforcing belt 222 are divided by the divided side reinforcing layer 220, so that the first of the carcass ply 10a is deformed at the carcass outermost position M. The side reinforcing belt 221 and the second side reinforcing belt 222 are prevented from being deformed together, and as a result, the bead filler 15 is also prevented from being deformed together.

  At this time, since the side reinforcing belt cords 221A and 222A of the first side reinforcing belt 221 and the second side reinforcing belt 222 are provided so as to satisfy 2 ° ≦ θ ≦ 40 °, the side reinforcing belt cords 221A and 222A Since the angle θ formed by the carcass cord 10A is larger than 2 °, the angle θ is too small and the first side reinforcing belt 221, the second side reinforcing belt 222 and the carcass cord 10A are substantially parallel to each other. It is possible to prevent that a strong reinforcing effect cannot be exhibited. On the other hand, since the angle θ is smaller than 40 °, it can be prevented that the angle θ is too large, the rigidity in the tire circumferential direction is lowered, and the effect of suppressing deformation strain is lowered.

  Here, in the first side reinforcing belt 221, the tip position of the one end portion 221a is set in a range of 5 mm or more and 10 mm or less from the filler proximal end position 15b on the inner side in the tire radial direction of the bead filler 15 to the outer side in the tire radial direction. The That is, the first side reinforcing belt 221 is provided such that the distance L3 between the tip position of the one end 221a and the filler base end position 15b satisfies 5 [mm] ≦ L3 ≦ 10 [mm]. Thereby, since the distance L3 between the distal end position of the one end 221a of the first side reinforcing belt 221 and the filler proximal end position 15b is larger than 5 [mm], the distance L3 is too narrow to reinforce the bead wire forming the bead core 14. An increase in local strain of the rubber member between the layer end portions can be prevented. On the other hand, since the interval L3 is narrower than 10 [mm], the interval L3 is too wide and the one end 221a of the first side reinforcing belt 221 is separated from the bead core 14 having high rigidity, and the entire first side reinforcing belt 221 is disposed. Can be prevented from being deformed with the load, and the effect of the divided side reinforcing layer 220 can be sufficiently exhibited.

  In the first side reinforcing belt 221, the tip position of the other end 221b is set in a range of 3 mm or more and 30 mm or less from the filler tip position 15a to the outer peripheral side in the tire radial direction. That is, the first side reinforcing belt 221 is provided so that the distance L4 between the tip position of the other end 221b and the filler tip position 15a is 3 [mm] ≦ L4 ≦ 30 [mm]. Thereby, since the distance L4 between the tip position of the other end 221b of the first side reinforcing belt 221 and the filler tip position 15a is larger than 3 [mm], the distance L4 is too narrow and the filler tip of the bead filler 15 It is possible to prevent the deformation from being suppressed and to prevent concentration of strain on the filler tip. On the other hand, since the distance L4 is narrower than 30 [mm], the distance L4 is too wide to prevent the tip end position of the other end 221b from approaching the carcass outermost position M, and the carcass outermost position M. Can be prevented from being affected by the deformation of the carcass ply 10a.

  On the other hand, in the second side reinforcing belt 222, the intrusion amount L5 in the tire width direction between the carcass layer 10 and the belt layer 11 at the tip end of the one end portion 222a is set in a range of 5 mm to 50 mm. That is, the tip position of the one end portion 222a of the second side reinforcing belt 222 is provided such that the amount of penetration L5 between the carcass layer 10 and the belt layer 11 is 5 [mm] ≦ L5 ≦ 50 [mm]. It is done. As a result, the second side reinforcing belt 222 has an intrusion amount L5 at the front end position of the one end portion 222a larger than 5 [mm], so that the intrusion amount L5 is too small to increase the tire circumferential rigidity. It is possible to prevent the steering stability from being improved. On the other hand, since the penetration amount L5 is smaller than 50 [mm], it is possible to prevent the penetration amount L5 from being too large and the weight of the second side reinforcing belt 222 from being excessively increased.

  As a whole, the divided side reinforcing layer 220 has an interval L2 in the tire radial direction between the tip position of the other end portion 221b of the first side reinforcing belt 221 and the tip position of the other end portion 222b of the second side reinforcing belt 222. It is set in the range of 10 mm or more and 40 mm or less. That is, the first side reinforcing belt 221 and the second side reinforcing belt 222 are provided so as to satisfy 10 [mm] ≦ L2 ≦ 40 [mm]. Thereby, since the distance L2 along the tire radial direction between the first side reinforcing belt 221 and the second side reinforcing belt 222 is larger than 10 [mm], the distance L2 is too narrow and the filler front end of the bead filler 15 is It is possible to prevent the carcass ply 10a from being affected by deformation of the carcass outermost position M via the first side reinforcing belt 221. On the other hand, since the distance L2 is narrower than 40 [mm], it is prevented that the distance L2 is too wide and the reinforcing area by the first side reinforcing belt 221 and the second side reinforcing belt 222 becomes small and the reinforcing effect is lowered. can do.

  According to the pneumatic tire 201 according to the present embodiment described above, by providing the filler tip position 15a at a position separated from the carcass outermost position M, the bead filler 15 in the vicinity of the filler tip position 15a is permanent. Accumulation of residual strain (permanent strain) is suppressed. Further, by setting the carcass ply 10a and the bead filler 15 in the vicinity of the filler tip position 15a so as to reduce the curvature of the carcass line 10d and to be close to a straight line, the carcass ply 10a and the bead 15 are beaded when a load is applied. The deformation of the contact portion with the tip of the filler 15 can be reduced, and local deformation including the tip of the bead filler 15 having a large influence on the flat spot resistance is suppressed. In addition, the filler tip of the bead filler 15 has a shape with less load dependency, and the steering stability is improved, and the length of the bead filler 15 toward the outer peripheral side in the tire radial direction is increased to increase the rigidity around the bead core 14. However, since local deformation near the filler tip position 15a is suppressed, it is possible to improve flat spot resistance and ensure sufficient steering stability. As a result, it is possible to improve flat spot resistance while maintaining steering stability.

  Furthermore, the pneumatic tire 201 according to the present embodiment described above is selected from the group consisting of polyester fibers, rayon fibers, and highly elastic fibers provided at a predetermined angle θ with respect to the carcass cord 10A of the carcass layer 10. It consists of side reinforcing belt cords 221A and 222A as at least one fiber cord, one end 221a is provided between the bead filler 15 and the carcass layer 10 in the tire width direction, and the other end 221b is the outermost carcass. The first side reinforcing belt 221 provided on the inner peripheral side in the tire radial direction from the position M, the one end 222a is provided between the carcass layer 10 and the belt layer 11, and the other end 222b is disposed on the tire from the carcass outermost position M. A divided side reinforcing layer 220 having a second side reinforcing belt 222 provided on the radially outer peripheral side. Provided.

  Therefore, the first side reinforcing belt 221 is provided on the inner side in the tire radial direction across the carcass outermost position M, and the second side reinforcing belt 222 is provided on the outer side in the tire radial direction. The deformation of the bead filler 15 can be suppressed by the reinforcing belt 221, the accumulation of permanent residual strain (permanent strain) in the vicinity of the filler tip position 15 a of the bead filler 15 can be suppressed, and the tire can be tired by the second side reinforcing belt 222. The circumferential rigidity can be increased, and thus the steering stability can be improved. In addition, since the divided side reinforcing layer 220 is not provided in the vicinity of the carcass outermost position M where the strain is greatly bent and strain is easily concentrated when a load is applied, the vicinity of the carcass outermost position M is positively provided. Therefore, the amount of deformation of the carcass ply 10a and the like on the inner side in the tire radial direction and the outer peripheral side in the tire radial direction other than the vicinity of the carcass outermost position M can be further reduced. Further, the first side reinforcing belt 221 and the second side reinforcing belt 222 are prevented from being deformed together with the deformation of the carcass ply 10a at the carcass outermost position M. As a result, the bead filler 15 is It is also possible to prevent deformation together. For this reason, the filler tip of the bead filler 15 is not easily affected by the deformation of the carcass ply 10a at the carcass outermost position M, so that the structure is less dependent on the load. Spot property can be improved.

  Furthermore, according to the pneumatic tire 201 according to the present embodiment described above, the divided side reinforcing layer 220 is set such that the predetermined angle θ is in the range of 2 degrees to 40 degrees. Accordingly, since the side reinforcing belt cords 221A and 222A of the first side reinforcing belt 221 and the second side reinforcing belt 222 are provided so as to satisfy 2 ° ≦ θ ≦ 40 °, the angle θ is too small and proper reinforcement is performed. In addition to preventing the effect from being exhibited, it is possible to prevent the angle θ from being too large and the tire circumferential rigidity to be lowered, and the effect of suppressing deformation strain from being lowered.

  Furthermore, according to the pneumatic tire 201 according to the present embodiment described above, the divided side reinforcing layer 220 includes the tip position of the other end portion 221b of the first side reinforcing belt 221 and the other end of the second side reinforcing belt 222. A distance L2 in the tire radial direction from the tip position of the portion 222b is set in a range of 10 mm or more and 40 mm or less. Accordingly, since the first side reinforcing belt 221 and the second side reinforcing belt 222 are provided so as to satisfy 10 [mm] ≦ L2 ≦ 40 [mm], the interval L2 is too narrow and the filler front end of the bead filler 15 It is possible to prevent the portion from being affected by the deformation of the carcass ply 10a at the carcass outermost position M, and the interval L2 is too wide to be reinforced by the first side reinforcing belt 221 and the second side reinforcing belt 222. It can prevent that an area becomes small and a reinforcement effect falls.

  Furthermore, according to the pneumatic tire 201 according to the present embodiment described above, the first side reinforcing belt 221 has the distal end position of the one end portion 221a at the filler proximal end position 15b on the inner side in the tire radial direction of the bead filler 15. To 5 mm or more and 10 mm or less in the tire radial direction outer peripheral side. Therefore, the first side reinforcing belt 221 is provided so that the distance L3 between the tip position of the one end 221a and the filler base position 15b is 5 [mm] ≦ L3 ≦ 10 [mm]. It is possible to prevent the local strain of the rubber member between the bead wire forming the bead core 14 and the end portion of the reinforcing layer from increasing, and the interval L3 is too wide so that the one end 221a has a high rigidity from the bead core 14. It is possible to prevent the first side reinforcing belt 221 from being deformed with the load due to separation, and the effect of the divided side reinforcing layer 220 can be sufficiently exhibited.

  Furthermore, according to the pneumatic tire 201 according to the present embodiment described above, the first side reinforcing belt 221 has a tip position of the other end portion 221b of 3 mm or more and 30 mm or less from the filler tip position 15a to the outer peripheral side in the tire radial direction. Is set in the range. Therefore, the first side reinforcing belt 221 is provided so that the distance L4 between the tip position of the other end 221b and the filler tip position 15a is 3 [mm] ≦ L4 ≦ 30 [mm]. Can prevent the deformation of the filler tip of the bead filler 15 from being too narrow, and the distance L4 is too wide so that the tip of the other end 221b is close to the carcass outermost position M. It is possible to prevent the carcass ply 10a from being influenced by deformation of the carcass ply 10a at the carcass outermost position M.

  Furthermore, according to the pneumatic tire 201 according to the present embodiment described above, the second side reinforcing belt 222 is arranged in the tire width direction between the carcass layer 10 and the belt layer 11 at the tip position of the one end portion 222a. The penetration amount L5 is set in the range of 5 mm to 50 mm. Accordingly, the tip end position of the one end portion 222a of the second side reinforcing belt 222 is provided such that the amount of penetration L5 between the carcass layer 10 and the belt layer 11 is 5 [mm] ≦ L5 ≦ 50 [mm]. Therefore, it is possible to prevent the intrusion amount L5 from being too small to increase the tire circumferential rigidity and to improve the steering stability, and the intrusion amount L5 is too large. It can prevent that the weight of the side reinforcement belt 222 increases too much.

  FIG. 5 is a diagram showing the results of a performance test of a pneumatic tire according to an example of the present invention. An embodiment of the present invention will be described with reference to this figure. Pneumatic tires 1,201 according to the embodiment described above were prototyped, and performance evaluation tests of the pneumatic tires 1,201 and conventional pneumatic tires were performed. The performance evaluation test was conducted on two items, flat spot resistance and steering stability. In this performance test, a pneumatic tire having a tire size of 295 / 35ZR18 was mounted on a regular rim specified by JATMA, and a normal internal pressure and a normal load were applied to the pneumatic tire.

  As for the evaluation method of each test item, for flat spot resistance, first, the tire uniformity is measured in accordance with JASO C607 “Testing method for uniformity of automobile tires”, and reserves for 30 minutes at a speed of 150 km / h. After running, the drum is 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 sg and difference ΔRFV, the better the flat spot resistance. Here, the evaluation results are indicated by an index with the evaluation result of Comparative Example 1 described later as 100, and the larger the index, the better the flat spot resistance.

  Regarding the steering stability, the pneumatic tire 1 to be tested was mounted on a domestic 2.5 liter class vehicle, and this vehicle was run on the test course. Evaluation of the test was performed by sensory evaluation by a driver. The evaluation results are indicated by an index with the evaluation result of Comparative Example 1 described later as 100, and the larger the index, the better the steering stability.

  In this example, as shown in FIG. 5, one type as a comparative example to be compared with the present invention and ten types as examples of the present invention are tested by the above method. In the pneumatic tires shown in “Example 1” to “Example 10”, as described above, the carcass outermost position M, the filler tip position 15a, and the interval L1 are appropriately secured, and the vicinity of the filler tip position 15a. By making the carcass line curvature (1 / R2) of the carcass ply 10a close to a straight line, the positional relationship between the bead filler 15 and the carcass ply 10a is set appropriately. On the other hand, in the pneumatic tire shown in “Comparative example 1”, the positional relationship between the bead filler 15 and the carcass ply 10a is shifted from the proper positional relationship.

In the pneumatic tires shown in “Example 3” to “Example 10”, a rubber composition (VCR) satisfying E ₁₀₀ / E ₂₀ × 100 ≧ 60% is used as the bead filler 15. Further, the pneumatic tires shown in “Example 4” to “Example 10” are composed of a composite cord obtained by twisting two 1670 dtex aramid fibers and one 940 dtex nylon fiber for the reinforcing belt cord of the belt reinforcing layer 12. And 78 weight percent of the reinforcing belt cord is made of organic fibers having a glass transition temperature T _g ≧ 100 ° C.

  In addition, the pneumatic tires shown in “Example 5” to “Example 10” further include a divided side reinforcing layer 220, and the side reinforcing belts in “Example 5” to “Example 10”. The angle θ between the cords 221A, 222A and the carcass cord 10A, the distance L2 between the first side reinforcing belt 221 and the second side reinforcing belt 222, and the distance L3 between the tip position of the first side reinforcing belt 221 and the filler base end position 15b. The distance L4 between the tip position of the first side reinforcing belt 221 and the filler tip position 15a, the amount L5 of the tip position of the second side reinforcing belt 222, and the like are made different.

  As is apparent from FIG. 5, the pneumatic tires shown in “Example 1” to “Example 10” have a bead filler 15 and a carcass ply 10a of 10 [mm] ≦ L1 ≦ 50 [mm], SH. Since it is provided to satisfy x0.4 <R2 <SHx0.7, the flat spot resistance is improved while maintaining steering stability as compared with “Comparative Example 1”. Is done.

The pneumatic tires shown in “Example 3” to “Example 10” use a rubber composition (VCR) satisfying E ₁₀₀ / E ₂₀ × 100 ≧ 60% as the bead filler 15. Since the temperature dependence in the bead filler 15 is reduced and the change in rigidity associated therewith is reduced, both the steering stability and the flat spot resistance can be improved.

Further, the pneumatic tires shown in “Example 4” to “Example 10” are composed of a composite cord obtained by twisting two 1670 dtex aramid fibers and one 940 dtex nylon fiber for the reinforcing belt cord of the belt reinforcing layer 12. Since 78 weight percent of this reinforced belt cord is made of organic fibers having a glass transition temperature T _g ≧ 100 ° C., the weight distribution of the reinforced belt cord is set appropriately. The sex can be further improved.

  In addition, since the pneumatic tires shown in “Example 5” to “Example 10” include the divided side reinforcing layer 220, the rigidity in the tire circumferential direction is increased and the deformation of the bead filler 15 in the vicinity of the filler tip position 15a is also suppressed. Therefore, both handling stability and flat spot resistance can be improved. Further, the angle θ between the side reinforcing belt cords 221A and 222A and the carcass cord 10A, the distance L2 between the first side reinforcing belt 221 and the second side reinforcing belt 222, the distal end position of the first side reinforcing belt 221 and the filler proximal end position By optimizing the distance L3 from the front end 15b, the distance L4 between the front end position of the first side reinforcing belt 221 and the filler front end position 15a, the amount L5 of the front end position of the second side reinforcing belt 222, etc., the pneumatic tire is optimized. This shows that the steering stability and flat spot resistance of the vehicle can be maintained or improved.

  As described above, the pneumatic tire according to the present invention improves flat spot resistance while maintaining steering stability, and is useful when applied to a pneumatic tire having a flatness ratio of 50% or less.

It is meridional fragmentary sectional view containing the equatorial plane of the pneumatic tire which concerns on Embodiment 1 of this invention. It is meridional fragmentary sectional view which shows the principal part of the pneumatic tire which concerns on Embodiment 1 of this invention. It is meridional fragmentary sectional view containing the equatorial plane of the pneumatic tire which concerns on Embodiment 2 of this invention. It is a top view which shows the laminated structure of the carcass layer of the pneumatic tire which concerns on Embodiment 2 of this invention, and a division | segmentation side reinforcement layer. It is a figure which shows the result of the performance test of the pneumatic tire which concerns on the Example of this invention.

Explanation of symbols

1,201 Pneumatic tire 5 Tread surface 6 Tread portion 7 Shoulder portion 8 Side wall portion 9 Bead portion 10 Carcass layer 10A Carcass cord 10a Carcass ply 10b Carcass main body portion 10c Turn-up portion 10d Carcass line 11 Belt layer 12 Belt reinforcing layer 13 Inner Liner 14 Bead core 15 Bead filler 15a Filler tip position 15b Filler base position 50 Equatorial plane 220 Split side reinforcing layer (reinforcing layer)
221 First side reinforcing belt 222 Second side reinforcing belt 221A, 222A Side reinforcing belt cord A Virtual line B Virtual circle C Carcass line setting curve CA Outer peripheral side reference point CB Inner peripheral side reference point CO Center reference point

Claims (11)

It consists of at least one fiber cord selected from the group consisting of polyester fiber, rayon fiber, and highly elastic fiber, and a pair of bead cores on the tire radial direction outer peripheral side through bead fillers around the bead core from the inside in the tire width direction to the outside A carcass layer wound around and wound around, a belt layer made of a highly elastic fiber cord or steel cord and provided on the outer circumference in the tire radial direction of the carcass layer, and made of an organic fiber cord on the outer circumference in the tire radial direction of the belt layer In a pneumatic tire having a belt reinforcing layer provided,
The carcass layer and the bead filler are assembled in a normal rim and filled with a normal internal pressure corresponding to a normal load in a sectional view in the tire meridian direction,
The distance along the tire radial direction between the filler tip position on the outer circumferential side of the bead filler in the tire radial direction and the carcass outermost position on the outer side in the tire width direction of the carcass line of the carcass layer is in the range of 10 mm to 40 mm. And set to
A center reference point that is an intersection of an imaginary line parallel to the tire width direction from the filler tip position inward in the tire width direction and the carcass line, and an outer periphery in the tire radial direction from the center reference point in the carcass line The radius of the carcass line setting curve passing through the outer peripheral side reference point and the inner peripheral side reference point located within a predetermined range set in advance with respect to the side and the inner peripheral side is 0.4 times the height in the tire radial direction It is characterized by being set in a range that is larger than 0.7 times,
Pneumatic tire. The predetermined range is set by a virtual circle whose center is assumed to be the center reference point, and whose radius is assumed to be 1/30 to 1/5 of the height in the tire radial direction,
The outer peripheral side reference point and the inner peripheral side reference point are set by intersections of the virtual circle and the carcass line,
The pneumatic tire according to claim 1. The bead filler is made of a rubber composition having a retention rate of a storage elastic modulus measured at a temperature of 100 degrees with respect to a storage elastic modulus measured at a temperature of 20 degrees, which is 60% or more.
The pneumatic tire according to claim 1 or claim 2. The organic fiber cord of the belt reinforcing layer is composed of 75 weight percent or more and 90 weight percent or less and organic fibers having a glass transition temperature of 100 degrees or more,
The pneumatic tire according to any one of claims 1 to 3. It consists of at least one fiber cord selected from the group consisting of polyester fiber, rayon fiber, and highly elastic fiber that is provided at a predetermined angle with respect to the fiber cord of the carcass layer, and one end portion is located within the bead filler and the tire width direction. A first side reinforcing belt provided between the other carcass layer and having the other end provided on the inner side in the tire radial direction from the outermost position of the carcass, and one end provided between the carcass layer and the belt layer. It is provided with a reinforcing layer having a second side reinforcing belt provided between and at the other end portion provided on the outer peripheral side in the tire radial direction from the outermost position of the carcass.
The pneumatic tire according to any one of claims 1 to 4. The reinforcing layer is characterized in that the predetermined angle is set in a range of 2 degrees to 40 degrees,
The pneumatic tire according to claim 5. The reinforcing layer is set such that a distance in a tire radial direction between a tip position of the other end portion of the first side reinforcing belt and a tip position of the other end portion of the second side reinforcing belt is 10 mm or more and 40 mm or less. It is characterized by being
The pneumatic tire according to claim 5 or 6. In the first side reinforcing belt, a tip position of the one end portion is set in a range of 5 mm or more and 10 mm or less from a filler proximal end position on the tire radial inner peripheral side of the bead filler to a tire radial outer peripheral side. And
The pneumatic tire according to any one of claims 5 to 7. The first side reinforcing belt is characterized in that a tip position of the other end portion is set in a range of 3 mm or more and 30 mm or less from the filler tip position to the outer peripheral side in the tire radial direction.
The pneumatic tire according to any one of claims 5 to 8. The second side reinforcing belt is characterized in that the amount of penetration in the tire width direction between the carcass layer and the belt layer at the tip position of the one end is set in a range of 5 mm or more.
The pneumatic tire according to any one of claims 5 to 9. The aspect ratio is 50% or less,
The pneumatic tire according to any one of claims 1 to 10.

Images