JP2018158621A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for suppressing breakage of a breaker layer in travel time of a tire, and improving durability of a tire.SOLUTION: Two or more breaker layers 7, 8 are provided on outside of a tire radial direction of a carcass layer 4 of a tread part 1, a width TW1 of an outermost breaker layer 7 is wider than a width TW2 of other breaker layer 8, the outermost breaker layer 7 is arranged to cover the adjacent breaker layer 8 in the tire width direction, a cord angle θ2 of a second intermediate position P2 in the outermost breaker layer 7 is larger than a cord angle θ1 of a first intermediate position P1, and a difference (θ2-θ1) of these cord angles is 10°-25°, and an end count E2 of the second intermediate position P2 on the outermost breaker layer 7 is smaller than an end count E1 of the first intermediate position P1, and a difference (E1-E2) of these end counts is 10 pieces/50 mm-20 pieces/50 mm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire, and more specifically, by devising a structure of a breaker layer located on the outermost side in the tire radial direction, the breaker layer can be prevented from malfunctioning during running of the tire, and the durability performance of the tire is improved. The present invention relates to a pneumatic tire.

  In a pneumatic tire having a bias structure, a failure may occur starting from the edge portion of the breaker layer during traveling. One of the causes of such a failure is that the cords in the same breaker layer are narrow at the edge portion of the breaker layer, so that adjacent cords come into contact with each other and cause separation when the tire is bent. It is done. A countermeasure for reducing the number of cord ends in the breaker layer can be considered for such a problem, but there is a disadvantage that the tire strength is reduced.

  On the other hand, various pneumatic tires having a radial structure have been proposed in which the cord angle of the belt layer is changed for each portion 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, by having a structure in which the cord angle of the belt layer is relatively high in the tire center portion and relatively low in the tire shoulder portion, the durability performance and steering stability performance of the belt layer can be improved. it can. However, in the case of the structure as described above, there is a concern that the effect of improving the durability performance of the belt layer cannot be obtained sufficiently.

JP 2011-230538 A

  The object of the present invention is to improve the durability performance of the tire by suppressing the breaker layer failure during running of the tire by devising the structure of the breaker layer located on the outermost side in the tire radial direction. To provide tires.

  A 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, there are two or more breaker layers on the outer side in the tire radial direction of the carcass layer, 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 adjacent to the outermost breaker layer in the tire width direction, and the edge portion of the adjacent breaker layer is used as a reference line. The cord angle of the outer breaker layer with respect to the tire circumferential direction is an 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 between the reference line and the edge portion of the outermost breaker layer, is larger than the first intermediate position, and the difference between the cord angles is 10 ° to 25 °, and the outermost The number of ends of the breaker layer is smaller in the second intermediate position than in the first intermediate position, and the difference in the number of ends is 10/50 mm to 20/50 mm.

  In the present invention, there are two or more breaker layers on the outer side in the tire radial direction of the carcass layer in the tread portion, and the width of the outermost breaker layer located on the outermost side 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 in the tire width direction, and when the edge portion of the adjacent breaker layer is a reference line, the cord angle of the outermost breaker layer with respect to the tire circumferential direction is It is larger at the second intermediate position, which is the intermediate position between the reference line and the edge portion of the outermost breaker layer, than the first intermediate position, which is the intermediate position between the reference line and the central portion in the tire width direction of the outermost breaker layer. The tire strength at the first intermediate position is configured such that the number of ends of the outer breaker layer is smaller at the second intermediate position than at the first intermediate position. Relatively increased, it is possible to sufficiently secure the tire strength. Furthermore, 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 are The difference with the number is 10 pieces / 50 mm to 20 pieces / 50 mm, so that contact between adjacent cords when the tire is bent can be prevented. As a result, it is possible to suppress a breaker layer failure during traveling and improve the durability of the tire.

  In the present invention, in the outermost breaker layer, the cord angle at the first intermediate position is 20 ° to 35 °, the cord angle at the second intermediate position is 40 ° to 55 °, and the number of ends at the first intermediate position is 45/50 mm to 65/50 mm, and the number of ends at the second intermediate position is preferably 35/50 mm to 50/50 mm. Thereby, the contact of adjacent cords when the tire is bent can be prevented 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 that is the width of the tread surface, and the step amount from the adjacent breaker layer of the outermost breaker layer is 15 mm. It is preferable that it is -35mm. Thereby, since distortion applied to the breaker layer when the tire is bent can be reduced, the durability performance of the tire is improved.

  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. Thereby, since distortion applied to the breaker layer when the tire is bent can be reduced, the durability performance of the tire is improved.

  In the present invention, the minimum value of the inter-cord distance between the cord of the outermost breaker layer and the cord of the adjacent cord layer adjacent to the edge portion of the outermost breaker layer is preferably 0.2 mm or more. Thereby, the contact of the adjacent cords when the tire is bent can be prevented, and the durability performance of the tire is improved.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. FIG. 2 is a development view showing an outermost breaker layer extracted from the pneumatic tire of FIG. 1. It is sectional drawing which expands and shows the edge part of the outermost breaker layer of the pneumatic tire of FIG.

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

  As shown in FIG. 1, a pneumatic tire according to an embodiment of the present invention includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions that are disposed on both sides of the tread portion 1. 2 and 2 and a pair of bead portions 3 and 3 disposed on the inner side in the tire radial direction of the sidewall portions 2.

  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 includes 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 inclined with respect to the tire radial direction, and has a bias structure in which the carcass cords are arranged so as to cross each other. In the carcass layer 4, the angle of the carcass cord with respect to the tire circumferential direction is set in a range of 20 ° to 45 °, for example. 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 disposed on the outer periphery of the bead core 5. The outer carcass layer 4 </ b> A and the inner carcass layer 4 </ b> B are wound around the bead core 5 from the tire inner side to the outer side and are arranged so as to wrap the bead core 5 and the bead filler 6. As the carcass cords constituting these carcass layers 4A and 4B, organic fiber cords such as nylon and polyester are preferably used. A finishing sheet 9 made of a textile material is disposed in 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 (two layers in FIG. 1) 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 inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross 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 a range of 20 ° to 35 °, for example. The breaker layers 7 and 8 are covered with rubber. The breaker layer 7 includes 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 two breaker layers 7 and 8 as shown in FIG. The width TW1 of the outermost breaker layer 7 is configured to be wider than the width TW2 of the other breaker layers 8. The outermost breaker layer 7 is disposed so as to cover the adjacent breaker layer 8 adjacent to the outermost breaker layer 7 in the tire width direction.

  FIG. 2 shows the outermost breaker layer 7 extracted from 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 defined as a reference line RL, and the reference line RL and the central portion in the tire width direction of the outermost breaker layer 7 (the tire center line CL in FIG. 2). Position) in the tire width direction is defined as a first intermediate position P1, and an 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 defined as a second intermediate position P2. . At this time, with respect to the cord angle θ of the outermost breaker layer 7 with respect to the tire circumferential direction, the cord angle θ at the first intermediate position P1 is the cord angle θ1, and the angle θ at the second intermediate position P2 is the cord 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 as the number of ends E1, and the number of ends E at the second intermediate position P2 is set as the number of ends E2. The cord angle θ2 of the second intermediate position P2 of the outermost breaker layer 7 is larger than the cord angle θ1 of the first intermediate position P1, and the end number 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 end number E1. The number of ends E is the number of cords driven per predetermined range (lines / 50 mm) and is measured in a direction orthogonal to the cords.

  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 end number E1 and the end number E2 is 10/50 mm to 20 / It is comprised so that it may be set to 50 mm. Further, the cord angle θ1 is 20 ° to 35 °, the cord angle θ2 is 40 ° to 55 °, the end number E1 is 45/50 mm to 65/50 mm, and the end number E2 is 35/50 mm. It is preferable that it is -50 pieces / 50mm.

  The pneumatic tire has two or more breaker layers 7 and 8 on the outer side in the tire radial direction of the carcass layer 4 in the tread portion 1, and the width TW1 of the outermost breaker layer 7 is the other breaker layer 8 (in FIG. 1). The outermost breaker layer 7 is wider than the width TW2 of the adjacent breaker layer 8), and is disposed so as to cover the adjacent breaker layer 8 in the tire width direction. The cord angle θ2 of the second intermediate position P2 of the outermost breaker layer 7 Is larger than the cord angle θ1 of the first intermediate position P1, and the end number E2 of the second intermediate position P2 of the outermost breaker layer 7 is configured to be smaller than the end number E1 of the first intermediate position P1. Thus, the tire strength at the first intermediate position P1 can be relatively increased, and the tire strength can be sufficiently ensured. Furthermore, in the outermost breaker layer 7, the difference (θ2−θ1) between the cord angle θ1 of the first intermediate position P1 and the cord 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. Contact can be prevented. As a result, it is possible to suppress a breaker layer failure during traveling and improve the durability of the tire.

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

  The outermost breaker layer 7 is preferably made of a textile material made of nylon cord having a thickness of 940 dtex / 2 to 1400 dtex / 2. Furthermore, the outermost breaker layer 7 is more preferably constituted by a cord having a diameter of 0.6 mm to 1.2 mm. Since the outermost breaker layer 7 is constituted by the cord having such dimensions, the strain applied to the breaker layers 7 and 8 when the tire is bent can be reduced, so that the durability performance of the tire is improved. Connected.

  As shown in FIG. 1, a portion where the rubber gauge t measured in the normal direction of the carcass layer 4 in the cross-sectional view of the tread portion 1 is the thickest is a tread end on both sides, and from one tread end to the other tread end. The length measured along the tread surface is defined as the tread development width TDW. On the other hand, as shown in FIG. 3, in the outermost breaker layer 7, the protruding amount from the edge portion 8 e of the adjacent breaker layer 8 is defined as a step amount S. At this time, the width TW1 of the outermost breaker layer 7 is 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 manner, distortion applied to the breaker layers 7 and 8 when the tire is bent can be reduced, which leads to an improvement in the durability performance of the tire.

  In FIG. 3, the distance between the cords of the cord 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 an inter-cord distance d. At this time, the minimum value of the inter-cord distance d is preferably 0.2 mm or more. In the aspect shown in FIG. 3, since the edge portion 7e of the outermost breaker layer 7 is disposed 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, the three breaker layers are embedded in the tread portion so that the edge portion of the innermost breaker layer and the edge portion of the outermost breaker layer are located adjacent to each other in the tire radial direction in the tread portion. When arranged, the adjacent code layer 10 corresponds to the innermost breaker layer. In any case, by appropriately setting the inter-cord distance d between the outermost breaker layer 7 and the adjacent cord layer 10, contact between adjacent cords when the tire is bent can be prevented. This leads to improved durability performance.

  Air 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 a T type emergency tire of tire size T155 / 70D17 In the entering tire, whether or not the outermost breaker layer is covered with the adjacent breaker layer, the cord angle θ1 of the first intermediate position P1 and the cord angle θ2 of the second intermediate position P2 in the outermost breaker layer, The difference between the end number E1 of the first intermediate position P1 and the end number E2 of the second intermediate position P2, and the difference between the cord angle θ1 of the first intermediate position P1 and the code angle θ2 of the second intermediate position P2 (θ2−θ1). The 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], of the outermost breaker layer The cord angle θ1 of the first intermediate position P1, the cord angle θ2 of the second intermediate position P2 of the outermost breaker layer, the end number E1 [lines / 50 mm] of the first intermediate position P1 of the outermost breaker layer, the first of the outermost breaker layer (2) End number E2 at the intermediate position P2 [lines / 50 mm], ratio of outermost breaker layer width TW1 to tread development width TDW (TW1 / TDW × 100%), step amount S from adjacent breaker layer of outermost breaker layer [Mm], cord material of the outermost breaker layer, cord thickness [dtex / 2] of the outermost breaker layer, cord diameter [mm] of the outermost breaker layer, cords in the outermost breaker layer and the adjacent breaker layer Tires of Comparative Examples 1 to 10 and Examples 1 to 14 in which the distance d [mm] was set as shown in Tables 1 to 3 were manufactured.

  In Tables 1 to 3, when the presence or absence of the cover of the outermost breaker layer on the adjacent breaker layer is “Yes”, the test tire has the outermost breaker layer wider than the other breaker layers, and the outermost breaker layer The breaker layer has a structure arranged so as to cover the adjacent breaker layer in the tire width direction.

  About these test tires, evaluation regarding durability performance was implemented and the result was combined with Tables 1-3, and was shown.

  Each test tire is assembled on a wheel with a rim size of 17 × 4T, and a drum tester with a drum diameter of 1700 mm is used. After running under conditions based on the US FMVSS109 standard, the load is increased by 15% every 4 hours. The mileage until failure occurred was measured. The evaluation results are shown as 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.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall 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 layers 8e Edge part 9 Finishing sheet 10 Adjacent cord layer (theta) Cord angle with respect to tire circumferential direction of outermost breaker layer RL Reference line P1 Intermediate position between first reference line and central portion of outermost breaker layer in tire width direction (first intermediate position)
P2 Intermediate position between the reference line and the edge of the outermost breaker layer (second intermediate position)
TDW tread deployment width TW1 Width of outermost breaker layer TW2 Width of other breaker layers

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,
There are two or more breaker layers on the outer side in the tire radial direction of the carcass layer in the tread portion, and the width of the outermost breaker layer located on the outermost side in the tire radial direction among the breaker layers is wider than the widths of the other breaker layers When the outermost breaker layer is disposed so as to cover the adjacent breaker layer adjacent to the outermost breaker layer in the tire width direction, and the edge portion of the adjacent breaker layer is used as a reference line, the outermost breaker layer The reference line and the edge portion of the outermost breaker layer than the first intermediate position where the cord angle of the layer with respect to the tire circumferential direction is an intermediate position between the reference line and the center portion in the tire width direction of the outermost breaker layer And the difference between these cord angles is 10 ° to 25 °, and the number of ends of the outermost breaker layer is A pneumatic tire characterized by being smaller in the second intermediate position than in the first intermediate position and having a difference in the number of ends of 10/50 mm to 20/50 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 2. The pneumatic tire according to claim 1, wherein 45/50 mm to 65/50 mm, and the number of ends at the second intermediate position is 35/50 mm to 50/50 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 surface of the tread portion, and the step amount from the adjacent breaker layer of the outermost breaker layer is 15 mm The pneumatic tire according to claim 2, wherein the pneumatic tire is ˜35 mm.   4. The pneumatic tire according to claim 3, wherein the outermost breaker layer is made of a textile material made of nylon cord having a thickness of 940 dtex / 2 to 1400 dtex / 2.   The minimum value of the distance between cords between the cord 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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