JP6773553B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Radial tires, which are currently the mainstream of pneumatic tires, include carcass plies that include carcass cords arranged along the meridional direction (that is, the direction orthogonal to the tire circumferential direction, also called the radial direction). Generally, a belt composed of a plurality of belt plies including a belt cord inclined with respect to the tire circumferential direction is provided on the outer periphery of the carcass ply in the tread portion so as to be bridged between the pair of bead portions.

In a pneumatic tire, it may be required to improve the lateral rigidity for steering stability while suppressing the increase in the vertical rigidity. In Patent Document 1, two carcass cords of carcass ply are arranged along the meridian direction in the lower part of the belt in order to increase the side rigidity and improve the steering stability without increasing the road surface rigidity more than necessary. It is disclosed that the side portion from the vicinity of the belt end to the bead core is inclined with respect to the meridian direction so that the carcass cords intersect between the two carcass plies. Although it is possible to improve the side rigidity by forming a semi-radial region by inclining the carcass cord in the sidewall portion in this way, not only the lateral rigidity but also the vertical rigidity is improved, and the riding comfort and riding comfort are improved. The traction property is impaired.

JP-A-2007-176304

In view of the above points, it is an object of the present invention to provide a pneumatic tire capable of increasing lateral rigidity and improving steering stability while suppressing an increase in vertical rigidity.

The pneumatic tire according to the embodiment of the present invention is a pneumatic tire including a carcass ply bridged between a pair of bead portions, and the carcass ply includes a first carcass cord arranged along the meridional direction. The first carcass ply includes a first carcass ply and a second carcass ply including a second carcass cord arranged along the meridional direction and arranged on the outer surface side of the first carcass ply, and the first carcass ply is the first carcass ply. The sidewall portion has a first inclined region in which one carcass cord is arranged along a direction in which the carcass cord is inclined with respect to the meridional direction, and the second carcass ply is a direction in which the second carcass cord is inclined with respect to the meridional direction. The sidewall portion has a second inclined region arranged along the above, and the first inclined region and the second inclined region are arranged adjacent to each other in the meridional direction in the sidewall portion.

According to the present embodiment, since the first carcass ply and the second carcass ply are provided with an inclined region in which the carcass cord is inclined in the sidewall portion, the lateral rigidity can be increased and the steering stability can be improved. Moreover, by arranging the first inclined region and the second inclined region adjacent to each other in the meridian direction instead of overlapping them, that is, by arranging them so as to be adjacent to each other, an extreme increase in vertical rigidity can be suppressed.

A half sectional view of a pneumatic tire according to an embodiment. The conceptual diagram which shows the structure of the 1st carcass ply and the 2nd carcass ply of the same pneumatic tire separately. Schematic side view showing the carcass ply configuration in the sidewall of the pneumatic tire

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The pneumatic tire T of the embodiment shown in FIG. 1 is a passenger car pneumatic tire, and has a tread portion 1 constituting a ground contact surface, a pair of left and right bead portions 3 fixed to a rim, and a tread portion 1 and a bead. It is provided with a pair of left and right sidewall portions 2 interposed between the portions 3. Note that FIG. 1 is a right half cross-sectional view of the tire T cut along the meridian cross section including the tire rotation axis. In this example, the tire T is symmetrical. In the figure, CL indicates the tire equatorial plane.

In the present specification, the tire radial direction means a direction perpendicular to the tire rotation axis, and is indicated by reference numeral RD in FIG. The tire width direction refers to a direction parallel to the tire rotation axis, and is indicated by reference numeral WD in FIG. The tire circumferential direction refers to a direction of rotation about the tire rotation axis, and is indicated by reference numeral CD in FIG. The meridian direction refers to a direction perpendicular to the tire circumferential direction, and is indicated by reference numeral MD in FIGS. 1 to 3.

An annular bead core 31 made of bead wires and a bead filler 32 made of hard rubber having a substantially triangular cross section narrower toward the tip side installed on the outer circumference of the bead core 31 are embedded in the bead portion 3. ..

A carcass ply 4 bridged in a toroidal shape is embedded in the tire T between a pair of bead portions 3. The carcass ply 4 is formed by arranging carcass cords as reinforcing materials in parallel with a predetermined number of driving pieces and covering them with topping rubber, and the carcass cords are arranged substantially at right angles to the tire circumferential direction, that is, along the meridian direction MD. Has been done. Examples of the carcass cord include organic fiber cords such as polyester fiber, rayon fiber, aramid fiber and nylon fiber, and steel cord.

A belt 11 is arranged between the carcass ply 4 and the tread rubber 12 on the outer peripheral side (that is, the outer side in the tire radial direction) of the carcass ply 4 in the tread portion 1. The belt 11 is provided so as to overlap the outer periphery of the crown portion of the carcass ply 4, and is usually composed of at least two belt plies. In this example, the belt 11 is composed of two belts, a first belt ply 11A as the maximum width belt and a second belt ply 11B arranged on the outer circumference thereof. The belt plies 11A and 11B are formed by inclining belt cords such as steel cords at a constant angle (for example, 10 ° to 35 °) with respect to the tire circumferential direction and arranging them at predetermined intervals in the tire width direction. The belt cords are arranged so as to intersect each other between the two belt plies 11A and 11B.

In this example, the belt reinforcing layer 13 is provided on the outer side of the belt 11 in the tire radial direction, that is, between the belt 11 and the tread rubber 12. The belt reinforcing layer 13 is composed of a cap ply having a cord extending substantially parallel to the tire circumferential direction.

A sidewall rubber 21 is provided on the outer surface side of the tire of the carcass ply 4 in the sidewall portion 2. A rim protector 22 is formed so as to project near the bead portion 3 of the sidewall portion 2. Reference numeral 23 is a buttress line composed of annular micro-ridges provided on the surface of the sidewall portion 2. Reference numeral 33 is a rubber chain provided on the bead portion 3.

In the present embodiment, the carcass ply 4 is composed of two inner and outer pieces, that is, the first carcass ply 41 on the inner surface side and the outer surface side thereof (that is, the outer peripheral side of the first carcass ply 41 in the tread portion 1). It is composed of a second carcass ply 42 arranged in. The carcass code of the first carcass ply 41 is referred to as the first carcass code 41D, and the carcass code of the second carcass ply 42 is referred to as the second carcass code 42D.

The first carcass ply 41 reaches the bead portion 3 from the tread portion 1 through the sidewall portion 2, and both ends thereof are folded back by the bead core 31 and locked. Therefore, the first carcass ply 41 includes a toroid-shaped main body 41A straddling the pair of bead cores 31 and a folded-back portion 41B folded around the bead core 31 from both ends of the main body 41A. The folded-back portion 41B is folded back around the bead core 31 from the inside to the outside in the tire width direction.

The second carcass ply 42 reaches the bead portion 3 from the tread portion 1 through the sidewall portion 2, and both ends thereof are folded back by the bead core 31 and locked. Therefore, the second carcass ply 42 includes a toroid-shaped main body portion 42A straddling between the pair of bead cores 31 and a folded-back portion 42B folded around the bead core 31 from both ends of the main body portion 42A. The folded-back portion 42B is folded back around the bead core 31 from the inside to the outside in the tire width direction.

The first carcass ply 41 includes a first carcass code 41D arranged along the tire meridian direction MD, and a first inclined region in which the first carcass code 41D is arranged along a direction inclined with respect to the meridian direction MD. 41C is provided in the sidewall portion 2. Specifically, as shown in FIG. 2, the first carcass code 41D of the first carcass ply 41 is arranged in the meridian direction MD, that is, the angles of the plurality of carcass codes 41D aligned with respect to the tire circumferential direction CD are Basically, it is substantially 90 °. The first carcass code 41D having such a basic arrangement has a portion inclined with respect to the meridian direction MD in the sidewall portions 2 on both sides, whereby the first inclined portion 2 on both side wall portions 2 is provided. Region 41C is formed. In this example, the carcass code 41D of the first inclined region 41C on both sides is inclined in the same direction with respect to the meridian direction MD, but may be inclined in the opposite direction. In regions other than the first inclined region 41C, the first carcass code 41D is arranged in the meridian direction MD.

The inclination angle of the first carcass cord 41D in the first inclination region 41C is not particularly limited, but the angle θ1 with respect to the tire circumferential direction is preferably 70 ° to 80 ° as the angle of the carcass ply member before molding, and vulcanization. The angle of the rear tire is preferably 60 ° to 75 °.

The second carcass ply 42 includes a second carcass code 42D arranged along the tire meridian direction MD, and a second inclined region in which the second carcass code 42D is arranged along the direction of inclination with respect to the meridian direction MD. 42C is provided in the sidewall portion 2. Specifically, as shown in FIG. 2, the second carcass code 42D of the second carcass ply 42 is basically arranged in the meridian direction MD, but with respect to the meridian direction MD in the sidewall portions 2 on both sides. A second inclined region 42C is formed in each of the sidewall portions 2 on both sides by providing the portions inclined and arranged. In this example, the carcass cords 42D of the second inclined regions 42C on both sides are inclined in the same direction with respect to the meridian direction MD, but may be inclined in the opposite direction. In regions other than the second inclined region 42C, the second carcass code 42D is arranged in the meridian direction MD.

The inclination angle of the second carcass cord 42D in the second inclination region 42C is not particularly limited, but the angle θ2 with respect to the tire circumferential direction is preferably 70 ° to 80 ° as the angle of the carcass ply member before molding, and vulcanization. The angle of the rear tire is preferably 60 ° to 75 °.

In this example, the first carcass code 41D in the first inclined region 41C and the second carcass code 42D in the second inclined region 42C have the same inclination angle (that is, θ1 = θ2) and are inclined with respect to the meridian direction MD. Is set in the opposite direction.

Although not shown, the boundary portion where the angle of each of the carcass codes 41D and 42D changes (that is, the boundary between the first inclined region 41C and the general portion on both sides thereof, and the second inclined region 42C and the general portion on both sides thereof). The carcass cords 41D and 42D are bent through a curved portion having a radius of curvature in order to suppress cord fatigue failure due to bending.

As shown in FIGS. 1 to 3, the first inclined region 41C and the second inclined region 42C are arranged adjacent to the meridian direction MD in the sidewall portion 2. Specifically, the first inclined region 41C and the second inclined region 42C are arranged so as to be staggered in the meridian direction MD so as not to overlap each other, except that both regions 41C and 42C are adjacent to each other so as to be continuous in the meridian direction MD. Is arranged.

In the present embodiment, the second inclined region 42C is arranged outside the first inclined region 41C in the tire radial direction. That is, the first inclined region 41C of the first carcass ply 41 located on the inner surface side of the tire is arranged inside in the tire radial direction, and the second inclined region 42C of the second carcass ply 42 located on the outer surface side of the tire is arranged outside in the tire radial direction. Has been done.

As shown in FIG. 3, in the sidewall portion 2, the first carcass code 41D of the first carcass ply 41 shown by the dotted line is inclined with respect to the meridian direction MD in the first inclined region 41C, and in that region, it is inclined. The second carcass code 42D of the second carcass ply 42 shown by the solid line is arranged in the meridian direction MD. Further, in the second inclined region 42C adjacent to the outer peripheral side of the first inclined region 41C, the second carcass code 42D is inclined with respect to the meridian direction MD, and the first carcass code 41D is in the meridian direction MD in that region. It is arranged.

As shown in FIG. 1, the first inclined region 41C and the second inclined region 42C are provided in the range R0 from the belt end 11E to the tip 32A of the bead filler 32 in this example. That is, the inclined region 43 in which the first inclined region 41C and the second inclined region 42C are combined is provided within the range R0 between the belt end 11E and the bead filler tip 32A. Here, the belt end 11E is the end of the belt 11 in the tire width direction, and in this example, is the terminal of the first belt ply 11A, which is the maximum width belt, in the tire width direction. The tip 32A of the bead filler 32 is the outer end in the tire radial direction of the bead filler 32.

Further, the upper end (that is, the outer peripheral end) 43A of the inclined region 43 is preferably located on the outer diameter side of the position 23A corresponding to the buttress line 23, and the lower end (that is, the inner peripheral end) 43B of the inclined region 43. Is preferably located on the inner diameter side of the tire maximum width position 24. Here, the position 23A corresponding to the buttress line 23 is the position of the normal line of the outer line of the carcass ply when passing through the buttress line 23 in the tire meridian cross section shown in FIG. Further, the maximum tire width position 24 is a position in the meridian direction in which the width of the tire cross section is maximized in a normal state with no load in which the tire is mounted on the normal rim and filled with the normal internal pressure, and the rim protector 22 or the like. This is the position where the width of the basic profile excluding protrusions is maximized.

In the present embodiment, as shown in FIG. 1, the outer peripheral end 43A of the second inclined region 42C is located within the range R1 on the outer diameter side of the position 23A corresponding to the buttress line 23 and on the inner diameter side of the belt end 11E. The inner peripheral end 43B of the first inclined region 41C is located within the range R2 on the inner diameter side of the tire maximum width position 24 and on the outer diameter side of the tip 32A of the bead filler 32. Specifically, the outer peripheral end 43A of the second inclined region 42C is located near the belt end 11E, and the inner peripheral end 43B of the first inclined region 41C is an intermediate point between the tire maximum width position 24 and the tip 32A of the bead filler 32. It is located in the vicinity.

The width W2 of the second inclined region 42C is preferably set to be equal to or greater than the width W1 of the first inclined region 41C (W1 ≧ W2), and in this example, the same width, that is, W2 = W1 is set. Here, the widths W1 and W2 of the first and second inclined regions 41C and 42C are lengths along the meridian direction MD, and are equal to the width of each region in the carcass ply member before molding.

In the present embodiment as described above, in the sidewall portion 2, the first carcass ply 41 and the second carcass ply 42 are provided with the first and second inclined regions 41C and 42C in which the carcass cords 41D and 42D are inclined. , Lateral rigidity can be increased to improve steering stability.

Moreover, by arranging the first inclined region 41C and the second inclined region 42C adjacent to each other in the meridian direction MD so as not to overlap with each other, it is possible to suppress an extreme increase in the vertical rigidity and reduce the riding comfort and traction. It can be suppressed. Specifically, as shown in FIG. 3, the boundary 44 between the first inclined region 41C and the second inclined region 42C is easily bent because the inflection point where the inclination of both carcass codes 41D and 42D changes is located. The vertical rigidity can be reduced.

According to the present embodiment, the first inclined region 41C and the second inclined region 42C are provided within the range R0 from the belt end 11E to the tip 32A of the bead filler 32, which contributes to the improvement of steering stability. Since the first and second carcass cords 41D and 42D are inclined at a large portion, the steering stability can be effectively improved. As for other parts, since the first and second carcass cords 41D and 42D are provided along the meridian direction MD, the length of the carcass cord is longer than that in the case where the carcass cord is tilted in the entire area of the carcass ply 4. The carcass can be shortened, leading to a reduction in tire weight.

According to the present embodiment, the following effects are exhibited by arranging the second inclined region 42C on the outer side of the first inclined region 41C in the tire radial direction. That is, the second inclined region 42C located on the outer diameter side can effectively increase the rigidity of the tire outer surface side in the tire buttress portion near the buttress line 23. When a lateral force is applied to the tire, the strain is large on the tire outer surface side of the buttress portion, so the second inclined region 42C of the second carcass ply 42 located on the outer surface side is set to the outer diameter side corresponding to the buttress portion. By arranging them, the lateral rigidity can be improved more effectively. Further, by providing the first inclined region 41C of the first carcass ply 41 on the inner diameter side thereof, it is possible to suppress an extreme change in rigidity with respect to the buttress portion.

Further, by setting the width W2 of the second inclined region 42C to be equal to or larger than the width W1 of the first inclined region 41C, the effect of improving the lateral rigidity can be enhanced.

In order to show the effect of the above embodiment, pneumatic tires (size: 225 / 40R18) of Examples and Comparative Examples were prototyped.

The tire of the first embodiment has the configuration of the above embodiment shown in FIGS. 1 to 3, and the tire circumferences of the first and second carcass codes 41D and 42D in the first inclined region 41C and the second inclined region 42C. The inclination angles θ1 and θ2 with respect to the direction were set to 67 ° in terms of the angle of the tire after vulcanization.

The tire of the second embodiment is an example in which the first inclined region 41C and the second inclined region 42C are arranged opposite to the tire radial direction with respect to the tire of the first embodiment (the first inclined region 41C is the second). (Arranged on the outer side in the tire radial direction of the inclined region 42C), and other configurations are the same as those in the first embodiment.

Comparative Example 1 is an example of a full radial structure in which the first and second carcass codes 41D and 42D of the first and second carcass ply 41 and 42 are arranged along the meridian direction in all regions and no inclined region is provided. (The angle of the carcass cord with respect to the tire circumferential direction: 90 °), and other configurations were the same as those of the first embodiment.

In Comparative Example 2, the first and second carcass cords 41D and 42D of the first and second carcass plies 41 and 42 were both set to 67 ° (angle in the tire after vulcanization) with respect to the tire circumferential direction in all regions. This is an example of a semi-radial structure arranged in an inclined manner, and other configurations are the same as those in the first embodiment.

In Comparative Example 3, the first carcass cord in which the first inclined region 41C and the second inclined region 42C were totally overlapped with respect to the tire of the first embodiment in a range corresponding to the inclined region 43 and inclined in the opposite direction. This is an example in which the 41D and the second carcass cord 42D are crossed with each other (partial semi-radial structure), and other configurations are the same as those in the first embodiment.

Steering stability, durability, longitudinal rigidity and lateral rigidity were measured and evaluated for each of the pneumatic tires of Examples and Comparative Examples. The measurement / evaluation method is as follows.

-Maneuvering stability: A test tire was attached to a domestic 2L sedan vehicle, and sensory evaluation was performed using the actual vehicle. The evaluation result is displayed as an index with the comparative example as 100, and the larger the index, the better the steering stability.

-Durability: In accordance with the conditions stipulated in the US automobile safety standard FMVSS139, a durability test is performed with a drum type tester, the mileage until a tire failure occurs, and the value of Comparative Example 1 is set to 100. It is displayed by the index. The larger the index, the better the durability.

-Vertical rigidity (rigidity in the tire radial direction): The tire is assembled to a rim of 18 x 8.0 J on a 50t rigidity tester at an air pressure of 220 kPa, and the vertical load is between 4.4 kN ± 490 N with a camber angle of 0 °. It was obtained by dividing the amount of change in vertical force in the above by the amount of change in vertical deflection in the vertical direction, and was expressed as an index with the value of Comparative Example 1 as 100. The larger the index, the larger the vertical rigidity.

Lateral rigidity (rigidity in the tire width direction): With a tire internal pressure of 220 kPa, rim: 18 x 8.0 J, and vertical load of 4.4 kN applied to a 50 t rigidity tester, a load of 30% of the vertical load is applied to the lateral force. The lateral bending amount was measured, and the lateral rigidity was obtained by dividing the lateral force by the lateral bending amount, and the value of Comparative Example 1 was set to 100 and displayed as an index. The larger the index, the larger the lateral rigidity.

The results are shown in Table 1. Compared to Comparative Example 1 which has a full radial structure, Comparative Example 2 in which the carcass cord is tilted in all areas is excellent in steering stability, but only in lateral rigidity. No, the vertical rigidity was also greatly increased. Therefore, it was inferior in ride comfort and traction. Further, in Comparative Example 2, the durability was also inferior. In Comparative Example 3, since the cord intersection was provided only in the sidewall portion, the increase in vertical rigidity was suppressed as compared with Comparative Example 2, but it was insufficient. On the other hand, in the first and second embodiments according to the present embodiment, the lateral rigidity can be improved while suppressing the increase in the vertical rigidity. Therefore, the steering stability is suppressed while suppressing the deterioration of the riding comfort and the traction property. I was able to improve the sex. In addition, deterioration of durability was also suppressed.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention as well as the invention described in the claims and the equivalent scope thereof.

T ... pneumatic tire, 1 ... tread part, 2 ... sidewall part, 3 ... bead part, 4 ... carcass ply, 11 ... belt, 11E ... belt end, 32 ... bead filler, 41 ... first carcass ply, 41C ... 1st inclined area, 41D ... carcass code, 42 ... 2nd carcass ply, 42C ... 2nd inclined area, 42D ... carcass code

Claims (5)

In a pneumatic tire with a carcass ply spanned between a pair of beads
The carcass ply includes a first carcass ply including a first carcass cord arranged along the meridian direction and a second carcass cord arranged along the meridian direction, and is arranged on the outer surface side of the first carcass ply. With a second carcass ply,
The first carcass ply has a first inclined region in a sidewall portion in which the first carcass cord is arranged along an inclined direction with respect to the meridian direction.
The second carcass ply has a second inclined region in the sidewall portion in which the second carcass cord is arranged along the direction inclined with respect to the meridian direction.
A pneumatic tire in which the first inclined region and the second inclined region are arranged adjacent to each other in the meridian direction in the sidewall portion. The pneumatic tire according to claim 1, wherein the first carcass cord in the first inclined region and the second carcass cord in the second inclined region have opposite inclinations with respect to the meridian direction. The pneumatic tire according to claim 1 or 2, wherein the first inclined region and the second inclined region are provided within a range from the end of the belt to the tip of the bead filler. The pneumatic tire according to any one of claims 1 to 3, wherein the second inclined region is arranged outside the tire radial direction of the first inclined region. The pneumatic tire according to claim 4, wherein the width of the second inclined region is set to be equal to or larger than the width of the first inclined region.

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