JP6852492B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire, and more specifically, by devising the structure of the breaker layer located on the outermost side in the tire radial direction, failure of the breaker layer during tire running is suppressed and the durability performance of the tire is improved. Regarding pneumatic tires that made it possible.

In a pneumatic tire provided with a bias structure, a failure may occur starting from the edge portion of the breaker layer during running. One of the causes of such a failure is that at the edge of the breaker layer, the cord spacing in the same breaker layer is narrow, so that when the tire bends, the adjacent cords come into contact with each other to cause separation. Be done. To deal with such a problem, it is conceivable to reduce the number of cord ends in the breaker layer, but there is a drawback that the tire strength is lowered.

On the other hand, in a pneumatic tire having a radial structure, various types have been proposed in which the cord angle of the belt layer is changed for each part of the tire center portion and the tire shoulder portion in order to improve the durability performance of the belt layer. For example, in Patent Document 1, the cord angle of the belt layer is relatively high in the tire center portion and relatively low in the tire shoulder portion, so that the durability performance and steering stability performance of the belt layer can be improved. it can. However, in the case of the above-mentioned structure, there is a concern that the effect of improving the durability performance of the belt layer cannot be sufficiently obtained.

Japanese Unexamined Patent Publication No. 2011-23538

An object of the present invention is to devise the structure of the breaker layer located on the outermost side in the radial direction of the tire, thereby suppressing the failure of the breaker layer during running of the tire and improving the durability performance of the tire. To provide tires.

The pneumatic tire for achieving the above object is a pneumatic tire having a bias structure in which at least two carcass layers including a plurality of carcass cords inclined with respect to the tire circumferential direction are mounted between a pair of bead portions. In the tread portion, two or more breaker layers are provided on the outer side of the carcass layer in the tire radial direction, and the width of the outermost breaker layer located on the outermost side of the breaker layer in the tire radial direction is the width of the other breaker layer. The outermost breaker layer is arranged so as to cover the adjacent breaker layer adjacent to the outermost breaker layer in the tire width direction, and when the edge portion of the adjacent breaker layer is used as a reference line, the outermost breaker layer is said to be the most wide. The edge of the reference line and the outermost breaker layer from the first intermediate position where the code angle of the outer breaker layer with respect to the tire circumferential direction is the intermediate position between the reference line and the central portion of the outermost breaker layer in the tire width direction. The second intermediate position, which is an intermediate position with the portion, is large, the difference between these cord angles is 10 ° to 25 °, and the number of ends of the outermost breaker layer is larger than that of the first intermediate position. It is characterized in that it is small and the difference in the number of these ends is 10/50 mm to 20/50 mm.

In the present invention, the carcass layer in the tread portion has two or more breaker layers on the outer side in the tire radial direction, and the width of the outermost breaker layer located on the outermost side in the tire radial direction among the breaker layers is the width of the other breaker layer. The outermost breaker layer is arranged so as to cover the adjacent breaker layer in the tire width direction, and when the edge portion of the adjacent breaker layer is used as a reference line, the code angle of the outermost breaker layer with respect to the tire circumferential direction is Larger and largest at the second intermediate position, which is the intermediate position between the reference line and the edge of the outermost breaker layer, than the first intermediate position, which is the intermediate position between the reference line and the center of the outermost breaker layer in the tire width direction. Since the number of ends of the outer breaker layer is configured to be smaller at the second intermediate position than at the first intermediate position, the tire strength at the first intermediate position is relatively increased and the tire strength is sufficiently secured. be able to. Further, in the outermost breaker layer, the difference between the cord angle at the first intermediate position and the cord angle at the second intermediate position is 10 ° to 25 °, and the number of ends at the first intermediate position and the end at the second intermediate position Since the difference from the number is 10 pieces / 50 mm to 20 pieces / 50 mm, it is possible to prevent the adjacent cords from coming into contact with each other when the tire bends. As a result, it is possible to suppress the failure of the breaker layer during traveling and improve the durability performance of the tire.

In the present invention, in the outermost breaker layer, the cord angle of the first intermediate position is 20 ° to 35 °, the cord angle of the second intermediate position is 40 ° to 55 °, and the number of ends of the first intermediate position is It is preferably 45 lines / 50 mm to 65 lines / 50 mm, and the number of ends at the second intermediate position is preferably 35 lines / 50 mm to 50 lines / 50 mm. As a result, it is possible to prevent the adjacent cords from coming into contact with each other when the tire is bent without impairing the tire strength.

In the present invention, the width of the outermost breaker layer is in the range of 75% to 100% with respect to the tread development width TDW which is the width of the tread portion of the tread portion, and the step amount of the outermost breaker layer from the adjacent breaker layer is 15 mm. It is preferably ~ 35 mm. As a result, it is possible to reduce the distortion applied to the breaker layer when the tire is bent, which leads to improvement in the durability performance of the tire.

In the present invention, the outermost breaker layer is preferably made of a textile material made of nylon cord having a thickness of 940 dtex / 2 to 1400 dtex / 2. As a result, it is possible to reduce the distortion applied to the breaker layer when the tire is bent, which leads to an improvement in the durability performance of the tire.

In the present invention, the minimum value of the distance between the cords of the outermost breaker layer and the cords of the adjacent cord layer adjacent to the edge portion of the outermost breaker layer is preferably 0.2 mm or more. As a result, it is possible to prevent the adjacent cords from coming into contact with each other when the tire is bent, which leads to an improvement in the durability performance of the tire.

It is a meridian cross-sectional view which shows the pneumatic tire which comprises the embodiment of this invention. It is a development view which shows by extracting the outermost breaker layer of the pneumatic tire of FIG. FIG. 5 is an enlarged cross-sectional view showing an edge portion of the outermost breaker layer of the pneumatic tire of FIG. 1.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. In addition, in FIG. 1 and FIG. 2, CL is a tire center line.

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

A carcass layer 4 including a plurality of carcass cords extending in the tire radial direction is mounted between the pair of bead portions 3 and 3. The carcass layer 4 has at least two layers, and the carcass layer 4 shown in FIG. 1 includes an outer carcass layer 4A located on the outer side in the tire radial direction and an inner carcass layer 4B located on the inner side in the tire radial direction in the tread portion 1. To do. The carcass layer 4 includes a plurality of carcass cords that are inclined with respect to the tire radial direction, and has a bias structure in which the carcass cords are arranged so as to intersect each other between layers. In the carcass layer 4, the angle of the carcass cord with respect to the tire circumferential direction is set in the range of, for example, 20 ° to 45 °. The carcass layer 4 is covered with rubber. An annular bead core 5 is embedded in each bead portion 3, and a bead filler 6 made of a rubber composition is arranged on the outer periphery of the bead core 5. The outer carcass layer 4A and the inner carcass layer 4B are wound around the bead core 5 from the inside to the outside of the tire, and are arranged so as to wrap the bead core 5 and the bead filler 6. As the carcass cord constituting these carcass layers 4A and 4B, an organic fiber cord such as nylon or polyester is preferably used. A finishing sheet 9 made of a textile material is arranged on each bead portion 3, and the finishing sheet 9 is wound up along the outer peripheral shape of the bead portion 3.

In the pneumatic tire, two or more layers (two layers in FIG. 1) of breaker layers 7 and 8 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These breaker layers 7 and 8 include a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to intersect each other between the layers. The reinforcing cords of the breaker layer 8 adjacent to the outer peripheral side of the carcass layer 4A are arranged so as to intersect with the carcass cords of the carcass layer 4A. The angle of the breaker layer 8 with respect to the tire circumferential direction is set in the range of, for example, 20 ° to 35 °. The breaker layers 7 and 8 are covered with rubber. The breaker layer 7 is composed of an outermost breaker layer 7 located on the outermost side in the tire radial direction in the tread portion 1 and a breaker layer 8 other than the outermost breaker layer 7. The other breaker layer 8 corresponds to the adjacent breaker layer 8 described later in the case of a pneumatic tire including the two-layer breaker layers 7 and 8 as shown in FIG. The width TW1 of the outermost breaker layer 7 is wider than the width TW2 of the other breaker layer 8. Further, the outermost breaker layer 7 is arranged so as to cover the adjacent breaker layer 8 adjacent to the outermost breaker layer 7 in the tire width direction.

FIG. 2 shows an extraction of the outermost breaker layer 7 of the pneumatic tire of FIG. As shown in FIG. 2, the edge line of the edge portion 8e of the adjacent breaker layer 8 is set as the reference line RL, and the center portion of the reference line RL and the outermost breaker layer 7 in the tire width direction (of the tire center line CL of FIG. 2). The intermediate position in the tire width direction with the position) is set as the first intermediate position P1, and the intermediate position in the tire width direction between the reference line RL and the edge line of the edge portion 7e of the outermost breaker layer 7 is set as the second intermediate position P2. .. At this time, regarding the code angle θ of the outermost breaker layer 7 with respect to the tire circumferential direction, the code angle θ at the first intermediate position P1 is defined as the code angle θ1, and the angle θ at the second intermediate position P2 is defined as the code angle θ2. Further, regarding the number of ends E in the outermost breaker layer 7, the number of ends E at the first intermediate position P1 is set to the number of ends E1, and the number of ends E at the second intermediate position P2 is set to the number of ends E2. The code angle θ2 of the second intermediate position P2 of the outermost breaker layer 7 is larger than the code angle θ1 of the first intermediate position P1, and the number of ends E2 of the second intermediate position P2 of the outermost breaker layer 7 is the first intermediate position P1. It is configured to be smaller than the number of ends E1 of. The number of ends E is the number of cords driven in a predetermined range (corresponding to 50 mm), and is measured in a direction orthogonal to the cord.

Further, the difference (θ2-θ1) between the cord angle θ1 and the cord angle θ2 is 10 ° to 25 °, and the difference (E1-E2) between the number of ends E1 and the number of ends E2 is 10/50 mm to 20 /. It is configured to be 50 mm. Further, the cord angle θ1 is 20 ° to 35 °, the cord angle θ2 is 40 ° to 55 °, the number of ends E1 is 45/50 mm to 65/50 mm, and the number of ends E2 is 35/50 mm. It is preferably ~ 50 pieces / 50 mm.

The pneumatic tire has two or more breaker layers 7 and 8 on the outer side of the carcass layer 4 in the tread portion 1 in the tire radial direction, and the width TW1 of the outermost breaker layer 7 is the other breaker layer 8 (in FIG. 1). Wider than the width TW2 of the adjacent breaker layer 8), the outermost breaker layer 7 is arranged so as to cover the adjacent breaker layer 8 in the tire width direction, and the code angle θ2 of the second intermediate position P2 of the outermost breaker layer 7 Is larger than the code angle θ1 of the first intermediate position P1, and the number of ends E2 of the second intermediate position P2 of the outermost circuit breaker layer 7 is smaller than the number of ends E1 of the first intermediate position P1. Therefore, the tire strength at the first intermediate position P1 can be relatively increased, and the tire strength can be sufficiently secured. Further, in the outermost breaker layer 7, the difference (θ2-θ1) between the code angle θ1 of the first intermediate position P1 and the code angle θ2 of the second intermediate position P2 is 10 ° to 25 °, and the first intermediate position. The difference (E1-E2) between the number of ends E1 of P1 and the number of ends E2 of the second intermediate position P2 is 10/50 mm to 20/50 mm, so that when the tire bends, the adjacent cords are connected to each other. Contact can be prevented. As a result, it is possible to suppress the failure of the breaker layer during traveling and improve the durability performance of the tire.

In the pneumatic tire, the code angle θ1 of the first intermediate position P1 in the outermost breaker layer 7 is 20 ° to 35 °, the code angle θ2 of the second intermediate position P2 is 40 ° to 55 °, and the first The number of ends E1 of the intermediate position P1 is preferably 45/50 mm to 65/50 mm, and the number of ends E2 of the second intermediate position P2 is preferably 35/50 mm to 50/50 mm. By appropriately setting the cord angles θ1, θ2 and the number of ends E1 and E2 of the outermost breaker layer 7 in this way, contact between adjacent cords when the tire bends is prevented without impairing the tire strength. can do.

Further, the outermost breaker layer 7 is preferably made of a textile material made of a nylon cord having a thickness of 940 dtex / 2 to 1400 dtex / 2. Further, it is more preferable that the outermost breaker layer 7 is composed of a cord having a diameter of 0.6 mm to 1.2 mm. By forming the outermost breaker layer 7 with a cord having such dimensions, it is possible to reduce the distortion applied to the breaker layers 7 and 8 when the tire is bent, so that the durability performance of the tire can be improved. Connect.

As shown in FIG. 1, the portion where the rubber gauge t measured along the normal direction of the carcass layer 4 in the cross-sectional view of the tread portion 1 is the thickest is defined as the tread ends on both sides, and one tread end to the other tread end. The length measured along the tread surface up to is defined as the tread unfolding width TDW. On the other hand, as shown in FIG. 3, in the outermost breaker layer 7, the amount of protrusion of the adjacent breaker layer 8 from the edge portion 8e is defined as the step amount S. At this time, the width TW1 of the outermost breaker layer 7 is preferably in the range of 75% to 100% with respect to the tread development width TDW, and the step amount S of the outermost breaker layer 7 is preferably 15 mm to 35 mm. By configuring the outermost breaker layer 7 in this way, it is possible to reduce the distortion applied to the breaker layers 7 and 8 when the tire is bent, which leads to an improvement in the durability performance of the tire.

Further, in FIG. 3, the distance between the cords of the outermost breaker layer 7 and the cord of the adjacent cord layer 10 adjacent to the edge portion 7e of the outermost breaker layer 7 is defined as the inter-cord distance d. At this time, it is preferable to configure the cord so that the minimum value of the distance d between the cords is 0.2 mm or more. In the embodiment shown in FIG. 3, since the edge portion 7e of the outermost circuit breaker layer 7 is arranged adjacent to the outer carcass layer 4A, the adjacent cord layer 10 corresponds to the outer carcass layer 4A. On the other hand, for example, three breaker layers are embedded in the tread portion so that the edge portion of the innermost breaker layer located on the innermost side in the tire radial direction and the edge portion of the outermost breaker layer are adjacent to each other in the tread portion. When arranged, the adjacent cord layer 10 corresponds to the innermost breaker layer. In either case, by appropriately setting the distance d between the cords in the outermost breaker layer 7 and the adjacent cord layer 10, it is possible to prevent the adjacent cords from coming into contact with each other when the tire bends, and the tire. It leads to the improvement of the durability performance of.

A T-type emergency tire with a tire size of T155 / 70D17, which has a bias structure in which at least two carcass layers including a plurality of carcass cords inclined with respect to the tire circumferential direction are mounted between a pair of bead portions. In the input tire, whether or not the outermost breaker layer is covered with respect to the adjacent breaker layer, the magnitude of the code angle θ1 of the first intermediate position P1 and the code angle θ2 of the second intermediate position P2 in the outermost breaker layer, and the outermost breaker layer. The magnitude of the number of ends E1 of the first intermediate position P1 and the number of ends E2 of the second intermediate position P2, and the difference between the code angle θ1 of the first intermediate position P1 and the code angle θ2 of the second intermediate position P2 (θ2-θ1). , Difference between the number of ends E1 of the first intermediate position P1 and the number of ends E2 of the second intermediate position P2 (E1-E2) [lines / 50 mm], the code angle θ1 of the first intermediate position P1 of the outermost circuit breaker layer, the maximum The code angle θ2 of the second intermediate position P2 of the outer breaker layer, the number of ends E1 [piece / 50 mm] of the first intermediate position P1 of the outermost breaker layer, and the number of ends E2 [pieces] of the second intermediate position P2 of the outermost breaker layer. / 50mm], the ratio of the width TW1 of the outermost breaker layer to the tread development width TDW (TW1 / TDW x 100%), the step amount S [mm] from the adjacent breaker layer of the outermost breaker layer, the code of the outermost breaker layer The material, the thickness of the cord of the outermost breaker layer [dtex / 2], the diameter of the cord of the outermost breaker layer [mm], and the distance d [mm] between the cords of the outermost breaker layer and the adjacent breaker layer are shown in Tables 1 to 1. The tires of Comparative Examples 1 to 10 and Examples 1 to 14 set as in 3 were manufactured.

In Tables 1 to 3, when the presence or absence of covering the adjacent breaker layer of the outermost breaker layer is "yes", the width of the outermost breaker layer of the test tire is wider than the width of the other breaker layers, and the outermost tire is the outermost. It has a structure in which the breaker layer is arranged so as to cover the adjacent breaker layer in the tire width direction.

The durability performance of these test tires was evaluated, and the results are shown in Tables 1 to 3.

Each test tire is assembled to a wheel with a rim size of 17 x 4T, and a drum tester with a drum diameter of 1700 mm is used. After running under the conditions based on the US FMVSS109 standard, the load is increased by 15% every 4 hours to make the tire. The mileage until the failure occurred was measured. The evaluation result is shown by an index with Comparative Example 1 as 100. The larger the index value, the better the durability performance.

As can be seen from Tables 1 to 3, the durability of the tires of Examples 1 to 14 was improved as compared with Comparative Example 1 by devising the structure of the breaker layer located on the outermost side in the tire radial direction. On the other hand, in Comparative Examples 2 to 10, the effect of improving the durability performance was not sufficient.

1 Tread part 2 sidewall part 3 bead part 4 carcass layer 4A outer carcass layer 4B inner carcass layer 5 bead core 6 bead filler 7 outermost breaker layer 7e edge part 8 other breaker layer 8e edge part 9 finishing sheet 10 adjacent cord layer θ Code angle of the outermost circuit breaker layer with respect to the tire circumferential direction RL reference line P1 Intermediate position between the reference line and the central part of the outermost circuit breaker layer in the tire width direction (first intermediate position)
Intermediate position between the P2 reference line and the edge of the outermost breaker layer (second intermediate position)
TDW tread expansion width TW1 outermost breaker layer width TW2 other breaker layer width

Claims (5)

In a pneumatic tire having a bias structure in which at least two carcass layers including a plurality of carcass cords inclined with respect to the tire circumferential direction are mounted between a pair of bead portions.
The tread portion has two or more breaker layers on the outer side of the carcass layer in the tire radial direction, and the width of the outermost breaker layer located on the outermost side in the tire radial direction of the breaker layers is larger than the width of the other breaker layers. Widely, the outermost breaker layer is arranged so as to cover the adjacent breaker layer adjacent to the outermost breaker layer in the tire width direction, and when the edge portion of the adjacent breaker layer is used as a reference line, the outermost breaker layer is used. The reference line and the edge portion of the outermost breaker layer are more than the first intermediate position where the code angle of the layer with respect to the tire circumferential direction is the intermediate position between the reference line and the central portion of the outermost breaker layer in the tire width direction. The difference between these cord angles is 10 ° to 25 °, and the number of ends of the outermost circuit breaker layer is smaller in the second intermediate position than in the first intermediate position. A pneumatic tire characterized in that the difference in the number of ends is 10 pieces / 50 mm to 20 pieces / 50 mm. In the outermost breaker layer, the cord angle of the first intermediate position is 20 ° to 35 °, the cord angle of the second intermediate position is 40 ° to 55 °, and the number of ends of the first intermediate position is The pneumatic tire according to claim 1, wherein the tire is 45 pieces / 50 mm to 65 pieces / 50 mm, and the number of ends at the second intermediate position is 35 pieces / 50 mm to 50 pieces / 50 mm. The width of the outermost breaker layer is in the range of 75% to 100% with respect to the tread development width TDW which is the width of the tread portion of the tread portion, and the step amount of the outermost breaker layer from the adjacent breaker layer is 15 mm. The pneumatic tire according to claim 2, wherein the tire is ~ 35 mm. The pneumatic tire according to claim 3, wherein the outermost breaker layer is made of a textile material made of a nylon cord having a thickness of 940 dtex / 2 to 1400 dtex / 2. The fourth aspect of claim 4, wherein the minimum value of the distance between the cords of the outermost breaker layer and the cord of the adjacent cord layer adjacent to the edge portion of the outermost breaker layer is 0.2 mm or more. Pneumatic tires.

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