JP6059490B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  In order to improve the steering stability performance of a pneumatic tire, for example, in Patent Document 1 and Patent Document 2, a reinforcing layer is provided on a part of the tire side (for example, around the bead portion), thereby increasing the rigidity of the tire side. It is disclosed to improve the stability performance.

JP-A-6-1127 JP 2009-292415 A

  However, as shown in the above-mentioned patent document, if the rigidity on the tire side is simply increased, the longitudinal rigidity is also increased, the flexibility on the tire side is impaired, and the riding comfort is deteriorated. In particular, as shown in Patent Document 2, when a reinforcing layer having a metal cord such as a steel cord is disposed, the steering stability performance is greatly improved due to the rigidity of the metal cord, but the riding comfort is remarkably deteriorated.

  When cornering or driving, the belt layer tends to be displaced relative to the bead filler. That is, the tire side expands and contracts in the lateral direction (tire width direction) during cornering, and the tire side expands and contracts in the front-rear direction (tire circumferential direction) during driving. Since this expansion / contraction extends over the entire tire side, it is not sufficient from the viewpoint of improving steering stability performance to dispose the reinforcing layer only on a part of the tire side as in the above-mentioned patent document.

  In addition, when a reinforcing layer having a cord that is a foreign matter of rubber is disposed on the side of the tire where the deflection is large in the tire, the separation of the member may be caused from the end of the reinforcing member. Proper placement is required.

  The present invention has been made paying attention to such problems, and an object thereof is to provide a pneumatic tire that suppresses deterioration of member separation and riding comfort and improves steering stability performance. It is.

  In order to achieve the above object, the present invention takes the following measures.

That is, the pneumatic tire of the present invention includes a pair of bead portions having bead fillers, a carcass layer provided between the pair of bead portions, and a belt provided on the outer side in the tire radial direction of the carcass layer in the tread portion. A pneumatic tire comprising a layer,
A fiber reinforcement layer having an organic fiber cord that is inclined with respect to the tire circumferential direction and extends from the tread portion to the bead portion is provided, and the outer end portion in the tire radial direction of the fiber reinforcement layer includes the belt layer and the carcass layer. And the inner end portion in the tire radial direction of the fiber reinforcing layer is buried in the bead filler and sandwiched between the bead fillers.

  Thus, a fiber reinforcing layer having an organic fiber cord extending from the tread portion to the bead portion is provided, and both ends of the fiber reinforcing layer are sandwiched between the belt layer and the bead filler, respectively. As a result, the tire side stretch deformation can be suppressed, and the steering stability performance can be improved. Nevertheless, since both ends of the fiber reinforcement layer are sandwiched, it is possible to suppress the separation of the members. Moreover, since the organic fiber cord is used as the reinforcing layer, it is possible to suppress the deterioration of the riding comfort as compared with the case of the metal cord.

  In order to sufficiently secure the pinching force of the fiber reinforcement layer by the bead filler and to improve the steering stability performance, the inner end of the fiber reinforcement layer in the tire radial direction has the bead filler in the height direction that is the tire radial direction. It is preferable that it is arranged on the equally dividing boundary or on the inner side in the tire radial direction from this boundary.

  In order to achieve both suppression of deterioration in ride comfort and improvement in steering stability performance, the angle of the organic fiber cord embedded in the tire radial direction outer portion of the bead filler with respect to the tire circumferential direction is larger than the tire diameter than the bead filler. It is desirable that the organic fiber cord on the outside in the direction is set to be larger than the angle with respect to the tire circumferential direction.

  In order to further improve the steering stability performance by increasing the rigidity of the base end portion of the bead filler in the front-rear direction of the tire, the angle of the organic fiber cord embedded in the bead filler with respect to the tire circumferential direction is set to be larger than the tip end portion of the bead filler. It is effective that the proximal side portion is set smaller.

  As a preferred embodiment, the outer side in the tire radial direction than the bead filler is a first region, and the second region is from the boundary that bisects the bead filler in the height direction that is the tire radial direction to the tip of the bead filler. When the third region extends from the boundary to the base end of the bead filler, the angle of the organic fiber cord in at least a part of the first region with respect to the tire circumferential direction is 30 ° or more and less than 60 ° And the angle of the organic fiber cord in at least a part of the second region with respect to the tire circumferential direction is 45 ° or more and less than 75 °, and the organic fiber in at least a part of the third region The angle of the cord with respect to the tire circumferential direction is greater than 10 ° and 45 ° or less.

  In the case where the tire side is divided into a plurality of regions, the role of each region is differentiated, and in order to more appropriately balance the suppression of deterioration in ride comfort and the steering stability performance, at least one in the first region The angle of the organic fiber cord in the region of the tire with respect to the tire circumferential direction is α1, the angle of the organic fiber cord in at least a part of the second region with respect to the tire circumferential direction is α2, and the third region When the angle of a certain organic fiber cord with respect to the tire circumferential direction is α3, it is effective that the relationship α2> α1> α3 is established.

  In order to further improve the steering stability performance, the inner end in the tire radial direction of the fiber reinforcing layer passes through a point that bisects the flat surface on the outer side in the tire radial direction of the bead core in the tire width direction, and the bead filler is thickened. It is desirable to arrange | position on the division line divided in a direction, or a tire width direction inner side from this division line.

  In order to make the tire reversible and improve straight running stability, the fiber reinforcement layers are provided on both sides in the tire width direction to form a pair, and the organic fiber cord of the fiber reinforcement layer on the outside of the vehicle is The organic fiber cord of the fiber reinforcement layer on the inner side of the vehicle is inclined toward the leading side in the rotational direction with the inner end in the tire radial direction as the base point. It is effective.

The tire meridian cross-sectional view showing an example of the pneumatic tire according to the present invention. The tire meridian half section view of a pneumatic tire. The figure which shows typically the inclination with respect to the tire peripheral direction of the organic fiber cord of a fiber reinforcement layer. Explanatory drawing regarding the position of the fiber reinforcement layer edge part in a bead filler. Explanatory drawing which shows typically the direction of the organic fiber cord of the fiber reinforcement layer which makes the pair arrange | positioned at the tire width direction both sides. Explanatory drawing regarding the position of the fiber reinforcement layer edge part in the bead filler which concerns on other embodiment of this invention. (A) The figure which shows a certain embodiment. (B) The figure which shows embodiment other than the above. (C) The figure which shows embodiment other than the above.

  Hereinafter, a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the pneumatic tire is connected to a pair of annular bead portions 1, a sidewall portion 2 extending from the bead portion 1 to the outside in the tire radial direction RD, and an outer peripheral side end of the sidewall portion 2. A radial tire including a tread portion 3 and a carcass layer 4 provided between the pair of bead portions 1. The bead part 1 has a bead core 1a and a bead filler 1b. The carcass layer 4 is made of a toroidal carcass ply, and its end is folded back so as to sandwich the bead core 1a and the bead filler 1b.

  On the outer periphery of the carcass layer 4 in the tread portion 3, a belt layer 5 that reinforces the carcass layer 4 with a gag effect is disposed. The belt layer 5 has two first belt layers 5a and 5b having cords inclined at an angle of 20 to 30 ° with respect to the tire circumferential direction, and the cords of the belt layers are opposite to each other. It is laminated so as to intersect.

  On the outer peripheral side of the belt layer 5 in the tread portion 3, a tread rubber 7 constituting a ground contact surface is provided. A tread surface TR which is an outer surface of the tread rubber 7 is provided with a main groove (not shown) extending along the tire circumferential direction. Although not shown in detail, the tread rubber 7 has a cap-base structure in which a base rubber is laminated on the inner periphery of a cap rubber having a main groove.

  As shown in FIG. 1, when viewed in a tire meridian cross section, a belt reinforcing layer 6 is provided at a position covering the end 5at of the first belt layer 5a and the end 5bt of the second belt layer 5b. The belt reinforcement layers 6 are arranged on both sides of the tire width direction WD across the tire equator CL to form a pair. The belt reinforcing layers 6 are separated from each other in the tire width direction WD.

  As shown in FIG. 2, the fiber reinforcement layer 8 which has the organic fiber cord C from the tread part 3 to the bead part 1 is provided. Similar to the carcass layer 4, the fiber reinforcing layer 8 has a structure in which a plurality of organic fiber cords C are wrapped with rubber. An outer end portion 80 a in the tire radial direction of the fiber reinforcement layer 8 is sandwiched between the belt layer 5 and the carcass layer 4. Specifically, the tire radial direction outer end 80 of the fiber reinforcement layer 8 is located on the inner side in the tire width direction WD than the first belt layer end portion 5bt, and the separation of the member end is suppressed.

  The tire radial direction inner end portion 81b of the fiber reinforcing layer 8 is buried in the bead filler 1b and sandwiched between the bead fillers 1b. Specifically, the inner end 81 in the tire radial direction of the fiber reinforcement layer 8 reaches the bead core 1a. In other words, it can be said that the tire radial inner end 81 of the fiber reinforcement layer 8 is disposed on the inner side in the tire radial direction from the boundary br1 that bisects the bead filler 1b in the height direction that is the tire radial direction RD. In the present embodiment, the tire radial direction inner end 81 of the fiber reinforcement layer 8 reaches the bead core 1a. However, as shown in FIGS. 6A and 6B, the height direction (tire diameter) The bead filler 1b may be terminated in the bead filler 1b as long as it is arranged on the boundary br1 that bisects the bead filler 1b in the direction RD) or on the inner side in the tire radial direction RD from the boundary br1. Thereby, the pinching force of the fiber reinforcement layer 8 by the bead filler 1b is sufficiently ensured. On the other hand, as shown in FIGS. 6A and 6B, the tire radial direction inner end 81 of the fiber reinforcement layer 8 is on the boundary br1 that bisects the bead filler 1b in the height direction (tire radial direction RD) or Although it is preferable to be disposed inside the tire radial direction RD from the boundary br1, as shown in FIG. 6C, if it is buried in the bead filler 1b, it is located outside the boundary br1 outside the tire radial direction RD. It may be arranged.

  As shown in FIG. 4, the fiber reinforcing layer 8 is disposed between the first lane marking br2 and the second lane marking br3. The first partition line br2 passes through the point P1 that bisects the flat surface 1c on the outer side of the tire radial direction RD of the bead core 1a in the tire width direction WD, and partitions the bead filler 1b in the thickness direction. The second demarcation line br3 divides the bead filler 1b in the thickness direction through the point P3 located on the inner side in the tire width direction when the flat surface 1c is divided into four equal parts in the tire width direction WD. Thus, if the fiber reinforcement layer 8 is disposed offset inward in the tire width direction, the peri length (peripheral length) of the organic fiber cord can be secured.

  As shown in FIG. 3, the organic fiber cord of the fiber reinforcing layer has an angle with respect to the tire circumferential direction CD (hereinafter simply referred to as an angle) set to be greater than 0 ° and less than 90 °. Inclined with respect to the CD. As shown in FIG. 2, the outer side in the tire radial direction than the bead filler 1b is defined as a first region Ar1, and the second part extends from a boundary br1 that bisects the bead filler 1b in the height direction that is the tire radial direction RD to the bead filler tip 1d. The region Ar2 is defined as a third region Ar3 from the boundary br1 to the bead filler base end 1e. In the present embodiment, as shown in FIG. 3, the angle α1 of the organic fiber cord in at least a part of the first region Ar1 is 30 ° or more and less than 60 °. The angle α2 of the organic fiber cord in at least a part of the second region Ar2 is 45 ° or more and less than 75 °. The angle α3 of the organic fiber cord that becomes at least a part of the third region Ar3 is larger than 10 ° and not larger than 45 °. Here, at least a part of the region is set to change the angle in each region. It is not preferable to bend the organic fiber cord because distortion is concentrated and the organic fiber cord is curved. It is.

  The angles of the organic fiber cords in the first region Ar1, the second region Ar2, and the third region Ar3 are set such that a relationship of α2> α1> α3 is established. In this way, if the angle is varied for each region, the role of each region can be varied, and both suppression of deterioration in riding comfort and improvement in steering stability performance can be achieved.

  The reason is that since the organic fiber cord C is inclined with respect to the tire circumferential direction CD, it has an effect of improving the steering stability performance by ensuring the rigidity in the front-rear direction and the rigidity in the tire width direction. If the angle of the organic fiber cord is increased, the rigidity in the front-rear direction is reduced, but the tire radial direction (vertical direction) is easily deformed (flexed), and vertical expansion and deformation such as deformation at the time of overstepping is facilitated. . On the other hand, if the angle of the organic fiber cord is reduced, the organic fiber cord approaches the rotation direction, so that the rigidity in the tire front-rear direction can be increased.

  As shown in FIGS. 2 and 3, the angle α2 of the organic fiber cord embedded in the tire radial direction outer side portion (second region Ar2) of the bead filler 1b is an organic fiber located on the outer side in the tire radial direction than the bead filler 1b. It is set larger than the angle α1 of the cord. According to this configuration, the organic fiber cord in the first region Ar1 that is on the outer side in the tire radial direction than the bead filler 1b secures the rigidity in the tire front-rear direction and improves the steering stability performance. Nevertheless, the tip portion of the bead filler 1b is easily bent by the organic fiber cord in the second region Ar2 embedded in the outer portion of the bead filler 1b in the tire radial direction, thereby suppressing the deterioration of the riding comfort. Therefore, both suppression of deterioration in ride comfort and improvement in steering stability performance are achieved.

  Further, the angle of the organic fiber cord packed in the bead filler 1b is set to be smaller at the angle α3 at the base end side portion than at the angle α2 at the tip end portion of the bead filler. According to this configuration, since the tension acts from the bead core 1a on the base end portion of the bead filler 1b during rotation, the rigidity in the tire front-rear direction of the base end portion of the bead filler 1b is increased to further improve the steering stability performance. Is possible. Of course, in this embodiment, α1 <α3, but α1 = α3 may be used.

  As shown in FIG. 1, the fiber reinforcement layers 8 are provided on both sides of the tire width direction WD to form a pair. As schematically shown in FIG. 5, when the tire rotates in the direction of the arrow ro, the organic fiber cord C of the fiber reinforcing layer 8 b (see FIG. 1) on one side in the tire width direction is the inner end 81 in the tire radial direction. It is inclined to the lag side of the rotation direction from the base point. The tire circumferential direction is represented by CD. On the other hand, the organic fiber cord C of the fiber reinforcement layer 8a (see FIG. 1) on the other side in the tire width direction is inclined toward the advance side in the rotational direction with the tire radial direction inner end 81 as a base point. In this way, since the orientation of the organic fiber cords C of the paired fiber reinforcing layers 8a and 8b is reversed, the tire becomes reversible. Furthermore, in this embodiment, when the vehicle is mounted, the organic fiber cord C of the fiber reinforcement layer 8b that is on the outside of the vehicle is set to be on the delay side in the rotational direction with the tire radial direction inner end 81 as a base point, and the other vehicle inside The organic fiber cord C of the fiber reinforced layer 8a to be is configured to be on the advance side in the rotational direction with the tire radial direction inner end 81 as a base point.

  As an example of the tensile modulus of the organic fiber cord C, for example, the tensile modulus when stretched by 100% is 7.3-10.8 GPa. Examples of the material of the organic fiber cord C include nylon, polyester, and aramid.

  As described above, in the present embodiment, a pair of bead portions 1, 1 having the bead filler 1 b, the carcass layer 4 provided between the pair of bead portions 1, 1, and the tire of the carcass layer 4 in the tread portion 3. A pneumatic tire provided with a belt layer 5 provided on the outer side in the radial direction, provided with a fiber reinforcing layer 8 that has an organic fiber cord C that is inclined with respect to the tire circumferential direction CD and extends from the tread portion 3 to the bead portion 1. The outer end 80a in the tire radial direction of the fiber reinforcement layer 8 is sandwiched between the belt layer 5 and the carcass layer 4, and the inner end 81b in the tire radial direction of the fiber reinforcement layer 8 is buried in the bead filler 1b. It is sandwiched between bead fillers 1b.

  Thus, the fiber reinforcing layer 8 having the organic fiber cord C extending from the tread portion 3 to the bead portion 1 is provided, and both ends of the fiber reinforcing layer 8 are sandwiched between the belt layer 5 and the bead filler 1b, respectively. In addition, the restraint force during driving and driving can be improved, the tire side stretch deformation can be suppressed, and the steering stability performance can be improved. Nevertheless, since both ends 80 and 81 of the fiber reinforcing layer 8 are sandwiched, it is possible to suppress the separation of the members. Moreover, since the organic fiber cord C is used as the reinforcing layer, it is possible to suppress the deterioration of the riding comfort as compared with the case of the metal cord.

  In particular, in the present embodiment, the tire radial inner end 81 of the fiber reinforcement layer 8 is on the boundary br1 that bisects the bead filler 1b in the height direction that is the tire radial direction RD or on the inner side in the tire radial direction from the boundary br1. Is arranged. If comprised in this way, since the pinching force of the fiber reinforcement layer 8 by the bead filler 1b can be secured sufficiently, the fiber reinforcement layer 8 can be prevented from coming off from the bead filler 1b, and the restraining force at the time of cornering or driving can be sufficiently obtained. It is possible to accurately improve the steering stability performance with accuracy.

  Further, in the present embodiment, the angle α2 with respect to the tire circumferential direction of the organic fiber cord C buried in the tire radial direction outer side portion (second region Ar2) of the bead filler 1b is the tire radial direction outer side (first direction) than the bead filler 1b. It is set larger than the angle α1 with respect to the tire circumferential direction of the organic fiber cord C in one region Ar1). If comprised in this way, the rigidity of a tire front-back direction can be ensured with the organic fiber cord C in 1st area | region Ar1, and steering stability performance can be improved appropriately. In addition, the organic fiber cord C in the second region Ar2 makes it possible to easily bend the tip portion of the bead filler 1b and suppress deterioration in riding comfort. Therefore, it is possible to achieve both suppression of deterioration in riding comfort and improvement in steering stability performance.

  Further, in the present embodiment, the angle of the organic fiber cord C embedded in the bead filler 1b with respect to the tire circumferential direction is set such that the angle α3 of the base end portion is smaller than the angle α2 of the tip end portion of the bead filler 1b. Yes. Since the tension from the bead core acts on the base end portion of the bead filler during rotation, this configuration can increase the rigidity of the base end portion of the bead filler in the front-rear direction of the tire and further improve the steering stability performance. It becomes.

  In the present embodiment, a suitable angle α1 of the organic fiber cord C in at least a part of the first region Ar1 is 30 ° or more and less than 60 °, and at least a part of the second region Ar2. The preferred angle α2 of the organic fiber cord C in the region is 45 ° or more and less than 75 °, and the preferred angle α3 of the organic fiber cord C in at least a part of the third region Ar3 is It is larger than 10 ° and not larger than 45 °. Nevertheless, since the relationship of α2> α1> α3 is established for each of the above angles, the roles can be varied for each of the first to third regions, and the suppression of deterioration of ride comfort and the steering stability performance can be more appropriately performed. It is possible to achieve both.

  In the present embodiment, the inner end 81 in the tire radial direction of the fiber reinforcement layer 8 passes through the point P1 that bisects the flat surface 1c on the outer side in the tire radial direction of the bead core 1a in the tire width direction, and the bead filler 1b is thick. It is arrange | positioned on the division line br2 divided in a direction, or a tire width direction inner side from this division line br2. If comprised in this way, since the peri length (peripheral length) of an organic fiber cord can be ensured, it becomes possible to further improve steering stability performance.

  Furthermore, in this embodiment, the fiber reinforcement layers 8 (8a and 8b) are provided on both sides in the tire width direction to form a pair, and the organic fiber cord C of the fiber reinforcement layer 8b on the vehicle outer side is a tire. The organic fiber cord C of the fiber reinforcement layer 8a on the inner side of the vehicle is inclined toward the advancing side in the rotational direction with the radial inner end 81 as a base point. Inclined. If comprised in this way, a tire can be made reversible. Furthermore, while the fiber reinforcement layer on the outside of the vehicle is in a posture to appropriately receive the tension due to rotation, the fiber reinforcement layer on the inside of the vehicle is not in a posture to appropriately receive the tension due to rotation. It becomes possible to improve the straight running stability.

  In order to specifically show the configuration and effects of the present invention, the following evaluations were performed on the following examples.

(1) Ride comfort A tire having an internal pressure of 210 kPa was mounted on an actual vehicle, and the strength of vibration generated when the tire passed over a protrusion having a predetermined height was evaluated by sensory evaluation. The result of Comparative Example 1 is shown as an index with the value of 100, and the larger the value, the better the riding comfort.

(2) Steering stability performance A tire was attached to an actual vehicle, and the vehicle was run on a dry road surface and evaluated by sensory evaluation. The result of Comparative Example 1 is shown as an index with a value of 100, and the larger the value, the better the steering stability performance.

(3) Separation performance The drum traveled and the travel distance until a failure such as separation occurred was evaluated. The result of Comparative Example 1 is shown as an index with a value of 100, and the larger the value, the more the separation is suppressed.

Comparative Example 1
A tire of size 225 / 45R17 having a first belt layer and a second belt layer in the tread portion and a belt reinforcing layer disposed at a position covering the end portions of the first belt layer and the second belt layer was produced. The fiber reinforcement layer 8 is not disposed.

Comparative Example 2
A fiber reinforcing layer having an organic fiber cord C having an angle with respect to the tire circumferential direction CD of 45 ° was provided on the tire of Comparative Example 1. The outer end portion in the tire radial direction of the fiber reinforcement layer is sandwiched between the belt layer and the carcass layer. On the other hand, the inner end of the fiber reinforcing layer in the tire radial direction was interposed between the bead filler and the carcass layer. Otherwise, the tire was the same as the tire of Comparative Example 1.

Comparative Example 3
With respect to the tire of Comparative Example 2, the inner end portion in the tire radial direction of the reinforcing layer was buried in a bead filler and sandwiched between bead fillers. Moreover, the cord of the reinforcing layer is not an organic fiber but a metal cord such as steel. The inner end in the tire radial direction of the reinforcing layer reaches the bead core, and is arranged at a point P1 that bisects the flat surface of the bead core 1a in the tire width direction. Other than that, it was the same as the tire of Comparative Example 2.

Example 1
For the tire of Comparative Example 3, the cord of the reinforcing layer was made of organic fibers. Other than that, it was the same as the tire of Comparative Example 3.

Example 2
For the tire of Example 1, the angle α1 of the organic fiber cord C in the first region Ar1 and the angle α3 of the organic fiber cord C in the third region Ar3 are set to 45 °, and the second region Ar2 The angle α2 of an organic fiber cord C was set to 60 °. That is, the relationship of α2> α1 = α3 is satisfied. Otherwise, the tire was the same as the tire of Example 1.

Example 3
For the tire of Example 1, the angle α1 of the organic fiber cord C in the first region Ar1 is 45 °, the angle α2 of the organic fiber cord C in the second region Ar2 is 60 °, and the third region The angle α3 of the organic fiber cord C in Ar3 was set to 30 °. That is, the relationship of α2>α1> α3 is observed. Otherwise, the tire was the same as the tire of Example 1.

Example 4
With respect to the tire of Example 3, as shown in FIG. 6C, the boundary br <b> 1 that bisects the bead filler 1 b in the height direction (tire radial direction RD) of the tire radial direction inner end 81 of the fiber reinforcement layer 8. Further, it is arranged outside the tire radial direction RD and at a position terminating in the bead filler 1b. Other than that, it was the same as the tire of Example 3.

  From Table 1, it can be seen that Examples 1 to 4 have improved steering stability performance while suppressing separation of members and deterioration of riding comfort as compared with the comparative example. Specifically, as a premise, looking at Comparative Examples 1 and 2, it can be seen that providing a fiber reinforcing layer having a nylon cord improves steering stability performance while deteriorating riding comfort and separation performance.

  In Example 1, although the ride comfort is somewhat worse than that in Comparative Example 2, the separation performance is improved and the steering stability performance is dramatically improved. From this, it can be seen that by embedding the inner end in the tire radial direction of the fiber reinforced layer in the filler, the restraining force at the time of cornering or driving is improved, and the steering stability performance is improved.

  As can be seen from Example 1 and Comparative Example 3, when the cord of the fiber reinforcement layer is steel, the handling stability is improved, but the rigidity is excessively increased and the ride comfort and the separation performance are remarkably deteriorated.

  In the second embodiment, the ride comfort and the handling stability performance are improved compared to the first embodiment. This shows that the role of the fiber reinforcement layer 8 is made different between the first region Ar1 and the second region Ar2, and both the suppression of deterioration in ride comfort and the improvement of the steering stability performance are achieved.

  The riding comfort and handling stability performance of the third embodiment is improved compared to the second embodiment. This is considered to be that by reducing the angle of the cord C in the third region Ar3, the rigidity in the front-rear direction of the tire in the third region Ar3, which is the bead filler base end portion, is increased, and the steering stability is improved. Furthermore, it is considered that the ride comfort is improved by lowering the rigidity in the vertical direction and the horizontal direction of the same part Ar3 from that of the second embodiment and loosening it in the bending direction.

  In the fourth embodiment, the length of the fiber reinforcing layer 8 embedded in the bead filler 1b is shorter than that in the third embodiment, and riding comfort, steering stability performance, and separation performance are all reduced. According to this, the tire radial direction inner end 81 of the fiber reinforcing layer 8 is on the boundary br1 that bisects the bead filler 1b in the height direction (tire radial direction RD) or as shown in FIG. It can be seen that it is preferable to be arranged inside the tire radial direction RD from the boundary br1. In addition, since the length of a fiber reinforcement layer differs between Example 4 and a comparative example, it is thought that it cannot compare.

  Since the angle is an inclination angle with respect to the circumferential direction, it can be set to a minus (−) angle unless there is a designation of either the advance side or the delay side in the rotational direction.

DESCRIPTION OF SYMBOLS 1 ... Bead part 1b ... Bead filler 1c ... Flat surface 3 ... Tread part 4 ... Carcass layer 5 ... Belt layer CD ... Tire circumferential direction C ... Organic fiber cord 8 ... Fiber reinforcement layer 8a ... Fiber reinforcement layer 8b inside a vehicle ... Vehicle Outer fiber reinforced layer 80a ... Outer end portion in the tire radial direction of the fiber reinforced layer 81b ... Inner end portion in the tire radial direction of the fiber reinforced layer 81 ... Inner end in the tire radial direction of the fiber reinforced layer Ar1 ... First region Ar2 ... First Second region Ar3 ... Third region br1 ... Boundary br2 ... Dividing line

Claims (8)

A pneumatic tire comprising a pair of bead portions having bead fillers, a carcass layer provided between the pair of bead portions, and a belt layer provided on the outer side in the tire radial direction of the carcass layer in the tread portion. ,
A fiber reinforcement layer having an organic fiber cord that is inclined with respect to the tire circumferential direction and extends from the tread portion to the bead portion is provided, and the outer end portion in the tire radial direction of the fiber reinforcement layer includes the belt layer and the carcass layer. And the tire radial direction inner end of the fiber reinforcing layer is buried in the bead filler and sandwiched between the bead fillers ,
The outer side in the tire radial direction from the bead filler is a first region, the boundary from the bead filler bisecting in the height direction that is the tire radial direction to the tip of the bead filler is the second region, and from the boundary to the bead filler A pneumatic tire in which the angle with respect to the tire circumferential direction of the organic fiber cord in at least a part of the second region is 45 ° or more and less than 75 ° when the base region is the third region .   The tire radial direction inner side end of the said fiber reinforcement layer is arrange | positioned in the tire radial direction inner side from the boundary which bisects the said bead filler in the height direction which is a tire radial direction, or this boundary. Pneumatic tire.   The angle with respect to the tire circumferential direction of the organic fiber cord buried in the tire radial direction outer portion of the bead filler is set to be larger than the angle with respect to the tire circumferential direction of the organic fiber cord located on the outer side in the tire radial direction than the bead filler. The pneumatic tire according to claim 1 or 2.   The pneumatic tire according to any one of claims 1 to 3, wherein an angle of the organic fiber cord embedded in the bead filler with respect to a tire circumferential direction is set to be smaller in a proximal end portion than in a distal end portion of the bead filler. . Before SL is an angle less than 30 ° or more and 60 ° with respect to the tire circumferential direction of the organic fiber cord in at least a part of the region in the first region, the organic fiber cord in at least a part of the region in the third region The pneumatic tire according to any one of claims 1 to 4, wherein an angle with respect to a tire circumferential direction is larger than 10 ° and not larger than 45 °.   The angle with respect to the tire circumferential direction of the organic fiber cord in at least a part of the first region is α1, and the angle of the organic fiber cord in at least a part of the second region with respect to the tire circumferential direction is α2. The pneumatic tire according to claim 5, wherein a relationship of α2> α1> α3 is established when an angle of the organic fiber cord in the third region with respect to the tire circumferential direction is α3.   An inner end in the tire radial direction of the fiber reinforcement layer passes through a point that bisects a flat surface on the outer side in the tire radial direction of the bead core in the tire width direction, or on the lane line that divides the bead filler in the thickness direction, or this lane line The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire is disposed on the inner side in the tire width direction.   The fiber reinforcement layers are provided on both sides in the tire width direction to form a pair, and the organic fiber cord of the fiber reinforcement layer on the vehicle outer side is inclined toward the delay side in the rotation direction with the tire radial inner end as a base point. The pneumatic tire according to any one of claims 1 to 7, wherein the organic fiber cord of the fiber reinforcement layer on the vehicle inner side is inclined toward the advancing side in the rotational direction with the tire radial direction inner end as a base point.

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