JP7070162B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire provided with an inner belt layer and an outer belt layer laminated on the outer peripheral side of the carcass layer in the tread portion, and more specifically, a pneumatic tire capable of achieving both weight reduction and plunger strength. Regarding.

In recent years, there has been an increasing demand for reduction of tire mass in order to improve the fuel efficiency of automobiles. In order to meet such demands, it is necessary to reduce the weight of the belt layer and the carcass layer, which are reinforcing members of pneumatic tires. However, if the number of steel cords and textile cords constituting the belt layer and the carcass layer is reduced in order to reduce the tire mass, the plunger strength will decrease.

The plunger strength (see, for example, Patent Documents 1 to 3) is a plunger immediately before the pneumatic tire is destroyed by pushing the tread portion of the pneumatic tire filled with air toward the inside in the tire radial direction with the plunger. It means the tire breaking energy calculated from the pushing force and the moving distance, and it is required to secure sufficient plunger strength especially for extra road tires.

In view of such a situation, there is a demand for a method capable of ensuring sufficient plunger strength while reducing the weight of pneumatic tires.

Japanese Unexamined Patent Publication No. 2011-25718 Japanese Unexamined Patent Publication No. 2011-51497 Japanese Unexamined Patent Publication No. 2015-209552

An object of the present invention is to provide a pneumatic tire capable of achieving both weight reduction and plunger strength.

The pneumatic tire of the present invention for achieving the above object has a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and these sidewall portions. A pair of bead portions arranged inside in the tire radial direction are provided, a carcass layer is mounted between the pair of bead portions, and an inner belt layer and an outer belt layer are provided on the outer peripheral side of the carcass layer in the tread portion. In laminated pneumatic tires
The void area SB (mm ² ) of the first rhombus formed by the cord intersecting between the inner belt layer and the outer belt layer is in the range of 0.10 <SB <1.60.
The void area SC (mm ² ) of the second rhombus formed by the cord intersecting between the carcass layer and the inner belt layer is in the range of 0.15 <SC <1.46.
When the gauge between the cords between the inner belt layer and the outer belt layer is GB (mm), the first plunger proof stress coefficient PB calculated by PB = 1 / (SB × GB) is 0.85 <. In the range of PB <9.85,
When the inter-cord gauge between the carcass layer and the inner belt layer is GC (mm), the second plunger proof stress coefficient PC calculated by PC = 1 / (SC × GC) is 0.95 <PC. It is characterized by being in the range of <6.60.

As a result of diligent research on the relationship between the structure of the reinforcing member of the pneumatic tire and the plunger strength, the present inventor has made a gap in the first rhombic portion formed by the cord intersecting between the inner belt layer and the outer belt layer. By reducing the area SB and the void area SC of the second rhombic portion formed by the cord intersecting between the carcass layer and the inner belt layer, the plunger strength is increased, and the inner belt layer and the outer side are also increased. It was found that the plunger strength is increased by reducing the cord-to-cord gauge GB between the belt layer and the cord-to-cord gauge GC between the carcass layer and the inner belt layer, which led to the present invention. be.

That is, in the present invention, the void area SB of the first rhombus portion, the void area SC of the second rhombus portion, the first plunger proof stress coefficient PB calculated by PB = 1 / (SB × GB), and PC = 1. By setting the second plunger proof stress coefficient PC calculated by / (SC × GC) within a predetermined range, the plunger strength can be increased without hindering the weight reduction.

In the present invention, the cord-to-cord gauge GB between the inner belt layer and the outer belt layer is in the range of 0.90 mm to 1.30 mm, and the cord-to-cord gauge GC between the carcass layer and the inner belt layer is 0.80 mm. It is preferably in the range of ~ 1.10 mm. Further, it is preferable that the cord angles of the inner belt layer and the outer belt layer with respect to the tire circumferential direction are in the range of 15 ° to 35 °, respectively, and the cord angles of the carcass layer with respect to the tire circumferential direction are in the range of 80 ° to 90 °. .. As a result, it is possible to achieve both the strength of the plunger and the weight reduction of the pneumatic tire at a higher level.

It is a cross-sectional view of the meridian which shows the pneumatic tire which comprises embodiment of this invention. It is a developed view which shows the carcass layer, the inner belt layer and the outer belt layer extracted in the pneumatic tire of this invention. It is a top view which shows the code of the inner belt layer and the outer belt layer extracted. It is sectional drawing which shows by extracting the inner belt layer and the outer belt layer. It is a top view which shows by extracting the code of the inner belt layer and the carcass layer. It is sectional drawing which shows by extracting the inner belt layer and the carcass layer.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention, and FIGS. 2 to 6 show a main part thereof.

As shown in FIG. 1, the pneumatic tire of the present embodiment has a tread portion 1 extending in the tire circumferential direction and forming an annular shape, and a pair of sidewall portions 2 and 2 arranged on both sides of the tread portion 1. And a pair of bead portions 3 and 3 arranged inside the sidewall portions 2 in the tire radial direction.

A single carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of carcass cords C (see FIG. 2) extending in the radial direction of the tire, and is wound around the bead core 5 arranged in each bead portion 3 from the inside to the outside of the tire. As the carcass cord C, an organic fiber cord such as polyester is preferably used. A bead filler 6 made of a rubber composition having a triangular cross section is arranged on the outer periphery of the bead core 5.

On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. The belt layer 7 includes an inner belt layer 7i located inside the tire radial direction and adjacent to the carcass layer 4, and an outer belt layer 7o located outside the tire radial direction and adjacent to the inner belt layer 7i. The inner belt layer 7i and the outer belt layer 7o each include a plurality of belt cords Bi and Bo (see FIG. 2) that are inclined with respect to the tire circumferential direction, and the belt cords Bi and Bo intersect each other between layers. Is located in. The cord angle of the belt layer 7 with respect to the tire circumferential direction is set in the range of, for example, 15 ° to 35 °. Steel cords are preferably used as the belt cords Bi and Bo constituting the belt layer 7.

On the outer peripheral side of the belt layer 7, at least one belt reinforcing layer is formed by arranging band cords at an angle of, for example, 5 ° or less with respect to the tire circumferential direction, if necessary, for the purpose of improving high-speed durability. 8 is arranged. It is desirable that the belt reinforcing layer 8 has a jointless structure in which at least one band cord is aligned and a strip material covered with rubber is continuously wound in the tire circumferential direction. As the band cord constituting the belt reinforcing layer 8, an organic fiber cord such as nylon, polyester or aramid is preferably used.

In a pneumatic tire having a reinforcing structure as described above, the cords Bi and Bo intersecting between the inner belt layer 7i and the outer belt layer 7o form a first rhombic portion X1 (see FIG. 3) in a plan view. The codes C and Bi intersecting between the carcass layer 4 and the inner belt layer 7i form a second rhombic portion X2 (see FIG. 5) in a plan view. The void area SB (mm ² ) of the first rhombus portion X1 is set in the range of 0.10 <SB <1.60, and the void area SC (mm ² ) of the second rhombus portion X2 is 0.15 <SC. It is set in the range of <1.46. The void area SB of the first rhombus portion X1 and the void area SC of the second rhombus portion X2 are values measured at the first rhombus portion X1 and the second rhombus portion X2 on the tire center position CL, respectively.

Further, when the gauge between the cords between the inner belt layer 7i and the outer belt layer 7o (the gauge between the center position of the belt cord Bi and the center position of the belt cord Bo) is set to GB (mm) (see FIG. 4). ), The first plunger proof stress coefficient PB (1 / mm ³ ) calculated by PB = 1 / (SB × GB) is set in the range of 0.85 <PB <9.85, and the carcass layer 4 and the inner belt. When the gauge between the cords with the layer 7i (the gauge between the center position of the carcass cord C and the center position of the belt cord Bi) is GC (mm) (see FIG. 6), PC = 1 / (SC ×). The second plunger proof stress coefficient PC (1 / mm ³ ) calculated by GC) is set in the range of 0.95 <PC <6.60. In addition, in FIGS. 4 and 6, in order to facilitate the understanding of the inter-cord gauges GB and Gc, for convenience, the upper-layer cord and the lower-layer cord are depicted as being parallel to each other. The upper cord and the lower cord intersect each other. These are the values measured at the tire center position CL for each of the cord-to-cord gauges GB and GC.

In the pneumatic tire configured as described above, the first plunger proof stress coefficient calculated by the void area SB of the first diamond-shaped portion X1, the void area SC of the second diamond-shaped portion X2, and PB = 1 / (SB × GB). By setting the second plunger proof stress coefficient PC calculated by PB and PC = 1 / (SC × GC) in the above range, it is possible to achieve both weight reduction and plunger strength.

Here, when the void area SB of the first rhombic portion X1 formed by the cords Bi and Bo intersecting between the inner belt layer 7i and the outer belt layer 7o is 0.10 mm ² or less, the effect of weight reduction is reduced. On the contrary, if it is 1.60 mm ² or more, the plunger strength becomes insufficient. In particular, the void area SB (mm ² ) of the first rhombic portion X1 is preferably in the range of 0.14 ≦ SB ≦ 0.85.

When the void area SC of the second rhombic portion X2 formed by the cords C and Bi intersecting between the carcass layer 4 and the inner belt layer 7i is 0.15 mm ² or less, the effect of weight reduction is reduced, and conversely, the effect of weight reduction is reduced. If it is 1.46 mm ² or more, the plunger strength decreases. In particular, the void area SC (mm ² ) of the second rhombic portion X2 is preferably in the range of 0.20 ≦ SC ≦ 0.85.

When the first plunger proof stress coefficient PB is 0.85 or less, the plunger strength decreases, and when it is 9.85 or more, the shear stress generated between the inner belt layer 7i and the outer belt layer 7o causes the interlayer separation. Is likely to occur. In particular, the first plunger proof stress coefficient PB (1 / mm ³ ) is preferably in the range of 1.05 ≦ PB ≦ 6.80.

When the second plunger proof stress coefficient PC is 0.95 or less, the plunger strength decreases, and when it is 6.60 or more, the shear stress generated between the carcass layer 4 and the inner belt layer 7i causes interlayer separation. It is easy to occur. In particular, the second plunger proof stress coefficient PC (1 / mm ³ ) is preferably in the range of 1.05 ≦ PC ≦ 4.95.

In the pneumatic tire, the gauge GB between the cords between the inner belt layer 7i and the outer belt layer 7o is in the range of 0.90 mm to 1.30 mm, and the cord between the carcass layer 4 and the inner belt layer 7i. The gauge GC is preferably in the range of 0.80 mm to 1.10 mm. As a result, it is possible to achieve both the strength of the plunger and the weight reduction of the pneumatic tire at a higher level. If the inter-cord gauges GB and GC are smaller than the lower limit value, inter-story separation is likely to occur, and conversely, if the gauges are larger than the upper limit value, the effect of weight reduction is reduced and the plunger strength is lowered. The belt cords Bi and Bo preferably have a cord diameter in the range of 0.40 mm to 0.80 mm and a cross section in the range of 0.10 mm ² to 0.28 mm ² . Further, it is preferable that the carcass cord C has a cord diameter in the range of 0.50 mm to 0.80 mm and a total fineness in the range of 1100 dtex to 2200 dtex.

Further, the code angles θi and θo of the inner belt layer 7i and the outer belt layer 7o with respect to the tire circumferential direction are in the range of 15 ° to 35 °, more preferably in the range of 20 ° to 30 °, respectively, and the tire of the carcass layer 4 The code angle θ with respect to the circumferential direction is preferably in the range of 80 ° to 90 °. As a result, it is possible to achieve both the strength of the plunger and the weight reduction of the pneumatic tire at a higher level. Here, if the code angles θi and θo are smaller than 15 °, the void area SB of the first rhombus portion X1 or the void area SC of the second rhombus portion X2 becomes large, which causes a decrease in the plunger strength, and conversely, 35. If it is larger than °, the function as the belt layer 7 is deteriorated.

With a tire size of 195 / 65R15, it is provided with a tread portion, a pair of sidewall portions, and a pair of bead portions, and a carcass layer is mounted between the pair of bead portions. In a pneumatic tire in which the outer belt layer is laminated, the cord angles θi and θo of the inner belt layer and the outer belt layer with respect to the tire circumferential direction, the cord-to-cord gauge GB between the inner belt layer and the outer belt layer, and the inner belt layer. The void area SB of the first rhombus formed by the cord intersecting with the outer belt layer, the first plunger proof stress coefficient PB [PB = 1 / (SB × GB)], and the carcass layer and the inner belt layer. Gauge between cords GC, gap area SC (mm ² ) of the second rhombus formed by the cords intersecting between the carcass layer and the inner belt layer, second plunger proof stress factor PC [PC = 1 / ( SC × GC)] was set as shown in Table 1, and the tires of Reference Example 1, Examples 1 to 6 and Comparative Examples 1 to 2 were manufactured. As the carcass cord constituting the carcass layer, a polyester cord having a cord diameter of 0.68 mm and a fineness of 1670 dtex / 2 was used. The code angle θ of the carcass layer with respect to the tire circumferential direction is 90 °. As the belt cord constituting the inner belt layer and the outer belt layer, a steel cord having a cord structure of 1 × 2 × 0.30 mm, a cord diameter of 0.6 mm, and a cross-sectional area of 0.14 mm ² is used. bottom.

The tire mass, plunger strength, and separation resistance of the tires of Standard Example 1, Examples 1 to 6, and Comparative Examples 1 to 2 were evaluated by the following test methods, and the results are also shown in Table 1.

Tire mass:
The mass of each test tire was measured and shown as an index with Reference Example 1 as 100. The smaller the index value, the lighter the weight.

Plunger strength:
Assemble each test tire to a wheel with a rim size of 15 x 6JJ, set the air pressure to 200 kPa, push the tread part of the test tire inward in the tire radial direction with a plunger, and the plunger pushing force just before the pneumatic tire breaks. The destructive energy calculated from the travel distance was calculated. The evaluation results are shown by an index with Reference Example 1 as 100. The larger this index value is, the higher the plunger strength is.

Separation resistance:
Each test tire is assembled to a wheel with a rim size of 15 x 6JJ and mounted on a drum tester, and the running test is started under the conditions that the air pressure is 170 kPa, the initial load is 80% of the JATTA specified load, and the speed is 50 km / h. Then, the load was increased by 10% every 4 hours, and the mileage until the separation failure occurred in the belt layer was measured. The evaluation results are shown by an index with Reference Example 1 as 100. The larger this index value is, the better the separation resistance is.

As can be seen from Table 1, the tires of Examples 1 to 6 were able to achieve both weight reduction and plunger strength in comparison with Standard Example 1. On the other hand, although the tire of Comparative Example 1 was able to achieve both weight reduction and plunger strength, the separation resistance deteriorated and there was a problem in practical use. Further, the tire of Comparative Example 2 had a significantly reduced plunger strength.

Next, with a tire size of 195 / 65R15, a tread portion, a pair of sidewall portions, and a pair of bead portions are provided, a carcass layer is mounted between the pair of bead portions, and the inside of the outer peripheral side of the carcass layer in the tread portion. In a pneumatic tire in which a belt layer and an outer belt layer are laminated, the cord angles θi and θo of the inner belt layer and the outer belt layer with respect to the tire circumferential direction, the cord-to-cord gauge GB between the inner belt layer and the outer belt layer, and the inner side. The void area SB of the first rhombus formed by the cord intersecting between the belt layer and the outer belt layer, the first plunger proof stress coefficient PB [PB = 1 / (SB × GB)], the carcass layer and the inner belt. Gauge between cords between layers GC, void area SC (mm ² ) of the second rhombus formed by the cords intersecting between the carcass layer and the inner belt layer, second plunger proof stress factor PC [PC = 1 / (SC × GC)] was set as shown in Table 2, and tires of Reference Example 11, Examples 11 to 17, and Comparative Examples 11 to 12 were manufactured. As the carcass cord constituting the carcass layer, a polyester cord having a cord diameter of 0.68 mm and a fineness of 1670 dtex / 2 was used. The code angle θ of the carcass layer with respect to the tire circumferential direction is 90 °. As the belt cord constituting the inner belt layer and the outer belt layer, a steel cord having a cord structure of 2 + 2 × 0.25 mm, a cord diameter of 0.65 mm, and a cross section of 0.20 mm ² was used.

The tire mass, plunger strength, and separation resistance of the tires of Reference Examples 11, Examples 11 to 17, and Comparative Examples 11 to 12 were evaluated by the above-mentioned test methods, and the results are also shown in Table 2. ..

As can be seen from Table 2, the tires of Examples 11 to 17 were able to achieve both weight reduction and plunger strength in comparison with the standard example 11. On the other hand, although the tire of Comparative Example 11 was able to achieve both weight reduction and plunger strength, the separation resistance deteriorated and there was a problem in practical use. Further, the tire of Comparative Example 12 had a significantly reduced plunger strength.

1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 7i Inner belt layer 7o Outer belt layer 8 Belt reinforcement layer C Carcass cord Bi, Bo Belt cord

Claims (3)

A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged inside the tire radial direction of these sidewall portions. In a pneumatic tire in which a carcass layer is mounted between the pair of bead portions and an inner belt layer and an outer belt layer are laminated on the outer peripheral side of the carcus layer in the tread portion.
The void area SB (mm ² ) of the first rhombus formed by the cord intersecting between the inner belt layer and the outer belt layer is in the range of 0.10 <SB <1.60.
The void area SC (mm ² ) of the second rhombus formed by the cord intersecting between the carcass layer and the inner belt layer is in the range of 0.15 <SC <1.46.
When the gauge between the cords between the inner belt layer and the outer belt layer is GB (mm), the first plunger proof stress coefficient PB calculated by PB = 1 / (SB × GB) is 0.85 <. In the range of PB <9.85,
When the gauge between the cords between the carcass layer and the inner belt layer is GC (mm), the second plunger proof stress coefficient PC calculated by PC = 1 / (SC × GC) is 0.95 <PC. Pneumatic tires characterized by being in the range of <6.60. The inter-cord gauge GB between the inner belt layer and the outer belt layer is in the range of 0.90 mm to 1.30 mm, and the inter-cord gauge GC between the carcass layer and the inner belt layer is 0.80 mm. The pneumatic tire according to claim 1, wherein the tire is in the range of about 1.10 mm. The code angles of the inner belt layer and the outer belt layer with respect to the tire circumferential direction are in the range of 15 ° to 35 °, respectively, and the code angles of the carcass layer with respect to the tire circumferential direction are in the range of 80 ° to 90 °. The pneumatic tire according to claim 1 or 2.

Images