JP2012091685A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of favorably maintaining high speed durability performance and reducing tire weight in the pneumatic tire including a belt layer.SOLUTION: In the pneumatic tire including a carcass layer 4, the belt layer 7 and a belt reinforcing layer 8, a ratio BW/TCW of the belt width BW to the tire contact width TCW in a belt layer 7A with narrower width is brought into a range of 0.60≤BW/TCW≤0.80, both ends of a belt layer 7B with a wider width are arranged in positions separated by 5 to 10 mm outward to the tire width direction from both the ends of the belt layer 7A with the narrower widths, and the belt reinforcing layer 8 is composed of a cord containing at least high elasticity organic fibers.

Description

  The present invention relates to a pneumatic tire having a belt layer, and more particularly to a pneumatic radial tire that maintains good high-speed durability and can reduce the weight of the tire.

  As a measure to reduce the weight of pneumatic tires that have a belt layer, it is effective to reduce the amount of steel cords that make up the belt layer with high specific gravity. For example, the diameter of the cord strands, the number of strands of cords, and the end It is conceivable to limit the number or the like to a specific range (see Patent Document 1), or to replace the steel cord with another low specific gravity material such as an aramid fiber cord (see Patent Document 2). As another method, it is conceivable to narrow the belt width.

  However, if the weight is reduced based on the above-described method, the tagging effect due to the belt layer is reduced, and therefore, the belt layer rises at the shoulder portion and the tire outer diameter growth is promoted. There is a problem that gets worse.

JP 7-117407 A JP-A-5-147404

  An object of the present invention is to solve the above-mentioned problems, and in a pneumatic tire having a belt layer, a pneumatic tire capable of maintaining high speed durability and reducing the weight of the tire is provided. There is.

  In order to achieve the above object, a pneumatic tire according to the present invention has a carcass layer mounted between a pair of left and right bead portions provided in the tire width direction, and the width is different on the outer peripheral side of the carcass layer in the tread portion. In a pneumatic tire in which a belt layer is disposed and a belt reinforcing layer is disposed on the outer peripheral side of the belt layer, a ratio between a belt width BW of a belt layer having a narrower width of the belt layers and a tire ground contact width TCW BW / TCW is set to a range of 0.60 ≦ BW / TCW ≦ 0.80, and both end portions of the belt layer having the wider width from the both ends of the belt layer having the narrower width are connected to the tire width. The belt reinforcing layer is formed of a cord including at least a highly elastic organic fiber, and is disposed at a position 5 to 10 mm apart on the outer side in the direction.

  In the present invention, the belt width BW of the narrower belt layer is set in a range of 0.60 ≦ BW / TCW ≦ 0.80 with respect to the tire ground contact width TCW, and both ends of the wider belt layer are set. By separating the width of the belt from the both ends of the narrower belt layer by 5 to 10 mm outward in the tire width direction, the width of both belt layers is made narrower than before, reducing the amount of belt layers used and reducing the tire weight. I can do it. Furthermore, since the end portions of the belt layers that are likely to be the starting point of the failure are separated from each other by 5 to 10 mm, the end failure of the belt layer can be suppressed. In addition, since the belt reinforcement layer is composed of cords containing at least highly elastic fibers, the belt layer ends are constrained without significantly increasing the tire weight, and the reduction in rigidity caused by narrowing the belt layer width is compensated for at high speed. Durability can be maintained well.

  In the present invention, the belt reinforcing layer overlaps with the narrower belt layer and is arranged so as to extend outward from the end of the wider belt layer in the tire width direction. It is preferable that the overlap length with the narrower belt layer is 20 mm or more, and the distance between the outer end of the belt reinforcing layer and the end of the wider belt layer is 10 mm or more. Thereby, the belt reinforcing layer can sufficiently cover the end portion of the belt layer, so that the high-speed durability performance can be improved.

  In this invention, it is preferable that a belt reinforcement layer consists of a composite fiber cord containing a high elastic organic fiber and a low elastic organic fiber. Thereby, in addition to the clamping force based on the high elastic organic fiber, the excellent adhesiveness of the low elastic organic fiber can be obtained, so that the high-speed durability performance can be further improved.

  In the present invention, it is preferable that the cord angle of the narrower belt layer with respect to the tire circumferential direction is smaller than the cord angle of the wider belt layer with respect to the tire circumferential direction. As a result, the circumferential rigidity of the narrower belt layer is increased and the tagging effect is improved, so that the high-speed durability performance of the tire can be further improved.

  In the present invention, the amount of wire per unit width of the wider belt layer is preferably 0.9 times or less of the amount of wire per unit width of the narrower belt layer. Thereby, since the belt layer of the wider one is further reduced in weight, the tire can be further reduced in weight.

  In the present invention, the ground contact width TCW is defined by JATMA. The tire is mounted on an applicable rim prescribed by JATMA, filled with the highest air pressure prescribed by JATMA, and placed horizontally against a flat plate in a stationary state. It is the maximum linear distance in the tire axial direction on the contact surface with the flat plate when a load corresponding to 80% of the maximum load capacity is applied.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention. It is a meridian half sectional view showing a pneumatic tire according to another embodiment of the present invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 each show a pneumatic tire according to an embodiment of the present invention.

  1 and 2, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 is mounted between the pair of left and right bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the tire inner side to the outer side around the bead core 5 disposed in each bead portion 3. A bead filler 6 is disposed on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by the main body portion and the folded portion of the carcass layer 4.

  On the other hand, on the outer peripheral side of the carcass layer 4 in the tread portion 1, two belt layers 7 made of steel cords are arranged so that the cords cross each other. The belt layer 7 includes a belt layer 7A having a narrower width and a belt layer 7B having a wider width. The positional relationship between the narrower belt layer 7A and the wider belt layer 7B is not particularly limited. As shown in FIG. 1, the wider belt layer 7B is disposed on the outer peripheral side of the carcass layer 4. The belt layer 7A having a narrower width can be disposed on the outer peripheral side. On the contrary, as shown in FIG. 2, the narrower belt layer 7A can be disposed on the outer peripheral side of the carcass layer 4, and the wider belt layer 7B can be disposed on the outer peripheral side.

  Further, a belt reinforcing layer 8 in which an organic fiber cord is spirally wound in the tire circumferential direction is provided on the outer peripheral side of the belt layer 7. The belt reinforcing layer 8 only needs to cover at least the end of the belt layer 7, and may be a full cover that covers the entire band of the belt layer 7 or an edge cover that covers only the end of the belt layer 7. Good. The belt reinforcing layer 8 may be a single layer or may be laminated in two or more layers.

  In this tire, the ratio BW / TCW of the belt width BW of the narrower belt layer 7A and the tire ground contact width TCW is set in a range of 0.60 ≦ BW / TCW ≦ 0.80. Thus, by reducing the belt width BW of the narrower belt layer 7A with respect to the tire ground contact width TCW, the amount of the belt layer 7 used is reduced, so that the tire weight can be reduced. Here, if the ratio BW / TCW is smaller than 0.60, the width of the narrower belt layer 7A becomes too narrow, so that the high-speed durability performance deteriorates. If the ratio BW / TCW is greater than 0.80, the belt layer 7 cannot be reduced sufficiently, and the effect of reducing the weight of the tire cannot be obtained.

  Further, both end portions of the wider belt layer 7B are arranged at positions spaced 5 to 10 mm outward from the both end portions of the narrower belt layer 7A in the tire width direction. By setting the distance between the end of the belt layer 7B having the wider width and the end of the belt layer 7A having the smaller width as described above, the width of the belt layer 7B having the wider width can be made larger than the conventional one. It is possible to reduce the tire weight by reducing the width and to separate the end portions of the belt layer 7 that are likely to be the starting point of failure, thereby suppressing the occurrence of the end failure. Here, if the distance between the end of the wider belt layer 7B and the end of the narrower belt layer 7A is smaller than 5 mm, the end of the belt layer 7 is too close and an end failure occurs. It becomes easy. If the separation distance is greater than 10 mm, the wider belt layer 7B becomes too wide, so the amount of belt used increases and the tire weight cannot be reduced.

  Moreover, in this invention, the belt reinforcement layer 8 is comprised with the code | cord | chord containing highly elastic organic fiber. By using a cord containing highly elastic organic fibers in this way, the end of the belt layer 7 is constrained without significantly increasing the tire weight, and the reduction in rigidity due to the narrowing of the width of the belt layer 7 is compensated for, thereby achieving high-speed durability performance. Can be maintained well. Here, the elastic modulus of the cord including the highly elastic organic fiber is in the range of 4.5 to 18.0 GPa in terms of the elastic modulus between the tensile loads of 10N to 99N. Such an elastic modulus is measured based on the measurement conditions of the initial tensile resistance specified in JIS L1017. If a low elastic organic fiber cord is used as the belt reinforcing layer 8, the end of the belt layer 7 cannot be constrained, so that the high-speed durability performance cannot be maintained.

In the present invention, the belt reinforcing layer 8 is disposed so as to overlap with the narrower belt layer 7A and to extend outward from the end of the wider belt layer 7B in the tire width direction. The overlapping length L _A between the belt layer 7A having the smaller width and the belt layer 7A is set to 20 mm or more, and the separation distance L _B between the outer end of the belt reinforcing layer 8 and the end portion of the wider belt layer 7B is set to 10 mm or more. It is preferable to make it. By defining the end portion position of the belt reinforcing layer 8 in this way, the belt reinforcing layer 8 sufficiently covers the end portion of the belt layer 7, so that high-speed durability performance can be improved. Here, overlap length L _A sufficient high-speed durability because it is impossible to cover sufficiently the ends of the narrower belt layer 7A is 20mm smaller than the width can not be obtained. Further, the distance L _B is not sufficient high-speed durability can not be obtained because it is not possible sufficiently to cover the end portion of the wider belt layer 7B is 10mm smaller than the width.

  In the present invention, the belt reinforcing layer 8 is preferably composed of a composite fiber cord including high-elasticity organic fibers and low-elasticity organic fibers. By using the composite fiber cord in this way, in addition to the tightening force based on the high elastic organic fiber, excellent adhesiveness of the low elastic fiber can be obtained, so that the high-speed durability performance can be further improved. Examples of the highly elastic organic fiber include an aramid fiber, a polyethylene naphthalate fiber, and a polyolefin ketone fiber. Examples of the low elastic organic fibers include nylon 6 fibers and nylon 66 fibers.

  In the present invention, it is preferable that the cord angle of the narrower belt layer 7A with respect to the tire circumferential direction is smaller than the cord angle of the wider belt layer 7B with respect to the tire circumferential direction. By defining the cord angle of the belt layer in this way, it is possible to increase the circumferential rigidity of the belt layer 7A having the narrower width, improve the tagging effect, and improve the high-speed durability performance. Here, the cord angle of the narrower belt layer 7A is preferably 15 to 35 °. The cord angle of the wider belt layer 7B is preferably 15 to 35 °. In particular, it is preferable to make the cord angle of the belt layer 7A having the smaller width smaller by 2 ° or more than the cord angle of the belt layer 7B having the wider width. If the angle difference is less than 2 °, the effect of improving the high-speed durability cannot be sufficiently obtained.

  In the present invention, the amount of wire per unit width of the wider belt layer 7B is 0.9 times or less, more preferably 0.6 times the amount of wire per unit width of the narrower belt layer 7A. It is good to set it above 0.9 times or less. By reducing the wire amount of the wider belt layer 7B in this way, it becomes possible to further reduce the weight of the wider belt layer 7B, thereby further reducing the weight of the tire. Specifically, the amount of wire per unit width is changed by changing the number of ends of the belt layer, the wire diameter, and the like.

  In the above description, as shown in FIGS. 1 and 2, the case where the two belt layers 7 including the belt layer 7A having the narrower width and the belt layer 7B having the wider width are provided is illustrated. In this case, a belt layer wider than the wider belt layer 7B can be added to provide three or more belt layers 7. When three or more belt layers 7 are provided, the arrangement of the additional belt layers is not particularly limited, and the inner peripheral side of the belt layer 7A having a smaller width, the outer peripheral side of the belt layer 7B having a wider width, The belt layer 7A having a narrower width and the belt layer 7B having a wider width can be disposed at an arbitrary position.

  When three or more belt layers 7 are provided, the distance between the end portions of each belt layer is preferably set to 5 to 10 mm in order to suppress the end portion failure of the belt layer 7. Further, in order to cover the end portion of the belt layer 7, it is preferable that the outer end of the belt reinforcing layer 8 is disposed 10 mm or more outside in the tire width direction from the end portion of the widest belt layer among all the belt layers 7. Further, in order to reduce the weight of the tire, the wire amount per unit width of all belt layers wider than the narrower belt layer 7A is set to the amount of wire per unit width of the narrower belt layer 7A. It is preferable to make it 0.9 times or less.

The tire size is common to 195 / 65R15, the ratio BW / TCW of the belt width BW to the grounding width TCW of the narrower belt layer, the cord material of the belt reinforcement layer, the cord elastic modulus of the belt reinforcement layer, the belt layer end The distance between each other, the overlap length L _A between the belt layer and the belt reinforcement layer having a smaller width, the separation distance L _B of the outer end portion of the belt reinforcement layer from the end of the belt layer having a wider width, and the width The cord angle of the narrower belt layer with respect to the tire circumferential direction, the cord angle of the wider belt layer with respect to the tire circumferential direction, and the wider belt layer with respect to the amount of wire per unit width of the narrower belt layer Ten types of tires of Conventional Examples 1-2, Comparative Examples 1-2, and Examples 1-6 in which the amount of wire per unit width was set as shown in Table 1 were manufactured. In these examples, as shown in FIG. 1, a cross-sectional structure is provided in which two belt layers and one edge cover layer are provided as belt reinforcing layers, and the belt width of the outer peripheral belt layer is narrowed. However, Conventional Example 2 is an example in which the belt reinforcing layer is not provided based on this cross-sectional structure.

  In the column of “Cord material of belt reinforcing layer” in Table 1, “Nylon” is nylon fiber cord (940T / 2), “Aramid” is aramid fiber cord (1100T / 2), “Aramid / nylon” is aramid It means a composite fiber cord composed of a fiber cord (1670T / 2) and a nylon fiber cord (1400T / 1).

  About these 10 types of test tires, the high-speed durability performance and the tire weight reduction rate were evaluated by the following evaluation methods, and the results are also shown in Table 1.

High-speed durability performance A test tire was assembled on a wheel having a rim size of 15 × 6 J, filled with air pressure of 230 kPa, loaded with a load of 4.5 kPa, and run on a rotating drum having a diameter of 1707.6 mm. The running speed was gradually increased, and the breaking speed when the tire broke down was measured. The evaluation results are shown as an index with Conventional Example 1 as 100. A larger index value means a higher fracture speed and better high-speed durability performance.

Tire weight reduction rate The weight of the test tire was measured. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. A larger index value means a better tire weight reduction rate.

  As can be seen from Table 1, each of Examples 1 to 5 improved the high-speed durability performance and the tire weight reduction ratio in comparison with Conventional Example 1.

  On the other hand, the conventional example 2 having no belt reinforcing layer, the comparative example 1 having a small ratio BW / TCW, and the comparative example 2 in which the belt reinforcing layer is made of a low elastic organic fiber cord can all reduce the weight of the tire. High-speed durability performance deteriorated.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 7A Narrow belt layer 7B Wide belt layer 8 Belt reinforcement layer

Claims (5)

A carcass layer is mounted between a pair of left and right bead portions provided in the tire width direction, two belt layers having different widths are disposed on the outer peripheral side of the carcass layer in the tread portion, and the outer peripheral side of the belt layer. In pneumatic tires with belt reinforcement layers,
The ratio BW / TCW of the belt width BW of the narrower belt layer of the belt layers to the tire ground contact width TCW is set in a range of 0.60 ≦ BW / TCW ≦ 0.80, and the width of the belt layers is Both ends of the wider belt layer are arranged at positions spaced 5 to 10 mm outward from the both ends of the narrower belt layer in the tire width direction, and the belt reinforcing layer includes at least highly elastic organic fibers. A pneumatic tire characterized by comprising cords.   The belt reinforcing layer overlaps with the narrower belt layer and is arranged so as to extend outward from the end of the wider belt layer in the tire width direction, and the belt reinforcing layer and the width are The overlapping length with the narrower belt layer is set to 20 mm or more, and the separation distance between the outer end of the belt reinforcing layer and the end portion of the wider belt layer is set to 10 mm or more. Item 2. The pneumatic tire according to Item 1.   The pneumatic tire according to claim 1 or 2, wherein the belt reinforcing layer is made of a composite fiber cord including high-elasticity organic fibers and low-elasticity organic fibers.   The cord angle with respect to the tire circumferential direction of the narrower belt layer is made smaller than the cord angle with respect to the tire circumferential direction of the wider belt layer. Pneumatic tires.   The wire amount per unit width of the wider belt layer is 0.9 times or less of the wire amount per unit width of the narrower belt layer. The pneumatic tire according to any one of the above.