JP2010162991A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for improving a ground contact shape with a road face. <P>SOLUTION: In the pneumatic radial tire including a pair of bead parts, a pair of side wall parts, a tread part continuing to both the side wall parts, and a carcass reinforcing each part of them by being extended to between the pair of bead parts in a toroidal shape, and in which a belt and a belt protective layer are sequentially disposed on the outer side in a tire diametrical direction of a carcass crown part, the relation of the count of the belt protective layer in a shoulder range from both side ends of the belt to 1/5 point of the belt entire width, the one in the middle range from 1/5 point to 2/5 point, and the one in the center range between 2/5 point, that are α, β, and γ, are set to be α≥γ>β. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having an improved contact shape with a road surface.

  If the tire circumferential length that is in contact with the road surface varies in the tire width direction, tires may cause uneven wear, road noise during high-speed driving, and unstable behavior during cornering. Therefore, it is not preferable. Therefore, conventionally, various proposals have been made for making the tire circumferential direction length that is in contact with the road surface constant in the tire width direction, that is, for the contact manner of the tire tread.

  For example, it has been proposed to take measures such as increasing or decreasing the number of cords to be applied to the belt protective layer depending on the tire width direction (see Patent Document 1) or appropriately selecting the material of the cord (see Patent Document 2). Yes.

JP 2005-75289 A JP 2001-322405 A

  In addition to the above examples, various proposals have been made regarding the ground contact mode of the tread. However, it is advantageous to improve the above-mentioned various characteristics by making the ground contact shape closer to a rectangle. Is required to implement.

  Accordingly, an object of the present invention is to provide a pneumatic tire in which various performances are improved by making the contact shape of the tread particularly close to a rectangle.

When the present inventors examined in detail the ground contact shape of the pneumatic tire, the tire in which the number of cords in the belt protective layer is constant in the tread width direction is indicated by a broken-line circle as shown in FIG. It became clear that the proper grounding shape was not obtained because of the part.
In FIG. 1, the tire size is 225 / 45R17, the belt protective layer having the same number of cords is provided in the entire belt range, and the pneumatic tire having the tread pattern shown in FIG. It is assembled to the appropriate rim, the inner pressure is sealed at 220 kPa, and the ground contact shape is measured when a load of 5.76 kN is applied.

  Such a phenomenon is considered to occur because the rigidity of the tread portion corresponding to the region indicated by the broken-line circle in FIG. 1 is higher than the other portions. Therefore, in order to suppress such a phenomenon, an attempt was made to reduce the rigidity of the tread portion of the region by arranging sipes or inclined grooves in the region, but the effect of improving the rectangular ratio of the tire contact shape is It was not enough.

  As a result of intensive studies to achieve the above object, the present inventors have found that the ground contact shape of the tire can be improved by optimizing the number of cords to be driven in the belt protective layer, and the present invention has been completed. .

That is, the gist of the present invention is as follows.
(1) The pneumatic tire according to the present invention includes a pair of bead portions, a pair of sidewall portions, and a tread portion connected to both sidewall portions, and extends in a toroid shape between the pair of bead portions. A pneumatic radial tire having a carcass to be reinforced, and a belt and a belt protective layer arranged in order on the outer side in the tire radial direction of the crown portion of the carcass,
The belt protection in the shoulder region from both ends of the belt to 1/5 point of the entire belt width, the intermediate region from the 1/5 point to 2/5 point, and the center region between the 2/5 points The number of implantations α, β, γ of the layer is in a relationship of α ≧ γ> β. Here, 1/5 points belong to the shoulder region and 2/5 points belong to the intermediate region.

  (2) The pneumatic tire according to (1), wherein the tread portion includes 3 to 4 main grooves extending in a tread circumferential direction on a tread surface.

  (3) The pneumatic tire according to (1) or (2), wherein at least a part of the shoulder region of the belt protective layer is three layers.

  (4) The pneumatic tire according to (3), wherein the belt protection layer has three layers in the shoulder region, one layer in the intermediate region, and two layers in the center region.

  According to the present invention, since the ground contact shape with the road surface of the tread is improved, a pneumatic tire excellent in uneven wear resistance (and wear resistance) can be provided. Here, uneven wear refers to uneven wear or the like in which only the shoulder portion is worn.

It is a figure which shows the contact state of a tire. It is sectional drawing of an example of the pneumatic tire of this invention. It is sectional drawing of the other example of the pneumatic tire of this invention. It is sectional drawing of the other example of the pneumatic tire of this invention. It is a figure which shows the contact state of a tire. It is a figure which shows the grounding state of an example of the tire of this invention. It is a figure which shows the grounding state of the other example of the tire of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 2 is a cross-sectional view of an example of the pneumatic tire of the present invention, and FIGS. 3 and 4 are cross-sectional views of other examples of the pneumatic tire of the present invention.

  As shown in FIG. 2, the pneumatic tire of the present invention has a pair of bead portions 1 and a pair of sidewall portions 2, and a tread portion 3 connected to both sidewall portions, and the pair of bead portions is interposed between the pair of bead portions. A carcass 4 that extends in a toroid shape and reinforces each part, and a belt 5 and a belt protective layer 6 are sequentially arranged on the outer side in the tire radial direction of the crown part of the carcass. The layer 6 is wound in a spiral shape.

Here, in the pneumatic tire of the present invention, the shoulder region A from the both ends 7 of the belt to 8 which is 1/5 point of the belt full width W, and from 1/5 point to 9 which is 2/5 point. It is important that the numbers α, β, and γ of the belt protective layer 6 in the intermediate region B and the center region C between the 2/5 points have a relationship of α ≧ γ> β. By disposing the belt protective layer in this manner, the defective portion of the ground shape as shown by the dotted circle in FIG. 1 is eliminated, and the ground shape becomes rectangular. Therefore, uneven wear resistance and tire life of the tire are improved. As a method for defining the number of driving in each region of the belt protective layer, for example, ribbon-shaped strips having different driving densities are prepared, and the belt protective layer is wound around each region by the same number of layers. Examples thereof include a method of forming a belt protective layer by winding a ribbon-like strip having the same driving density around each region with a different number of layers. Here, when used for a ribbon-shaped strip tire protective layer having the same driving density, as a specific arrangement of the belt protective layer, as shown in FIG. It is preferable that at least a part is three layers, as shown in FIG. 4, there are three layers in the shoulder region A, one layer in the intermediate region B, and two layers in the center region C. preferable.
2 to 4, the belt 5 includes two layers, but the number of layers is not particularly limited and can be appropriately selected.

  The shape of poor ground contact of the tire as shown in FIG. 1 is that the number of cords in the belt protective layer is constant in the tire width direction, and 3 to 4 main grooves extending in the tire circumferential direction on the tread surface. It tends to occur in tires having Therefore, when the pneumatic tire of the present invention is applied to such a tire, such a grounding failure can be effectively improved.

  Moreover, as said material, steel cords other than polyamide fiber, such as 6, 6 nylon, polyester fibers, such as polyethylene terephthalate, and organic fiber cords, such as an aromatic polyamide fiber, can be used conveniently.

  The pneumatic tire of the present invention includes a shoulder region from the both ends of the belt to 1/5 point of the entire belt width, an intermediate region from 1/5 point to 2/5 point, and a center region between 2/5 points. The number of driving α, β, γ of the belt protective layer is not particularly limited except that α ≧ γ> β, and it can be manufactured by a known method using a known tire structure. Further, as the gas filled in the pneumatic tire of the present invention, an inert gas such as nitrogen, argon, helium, etc. can be used in addition to air having a normal or oxygen partial pressure adjusted.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, and can be appropriately changed without departing from the scope of the present invention.

(Examples 1 and 2)
The configuration shown in FIG. 2 is obtained by winding a ribbon having a width of 6 mm and a thickness of 0.9 mm, which is formed by winding 6,6-nylon in parallel at 50/5 cm and covering with rubber. A pneumatic radial tire having a tread pattern shown in FIG. 1 was manufactured (size: 225 / 45R17) with a belt protective layer having the number of cords shown. Using these tires, the contact state with the road surface was measured in the same manner as described above. The results are shown in FIG. 5 for the comparative example, FIG. 6 for the example 1, and FIG. 7 for the example 2. Further, the rectangular ratio of each tire was calculated based on the above result. The results are shown in Table 1.
Here, as a rectangular ratio, the circumferential length b at the position of the circumferential direction length a on the tire equator plane and 80% of the ground contact width in the ground contact shape with the standard air pressure and the standard load attached to the standard rim. The ratio (b ₁ / a) to the rectangular ratio D ₁ , and the ratio (b ₂ / a) between the circumferential length a and the circumferential length b ₂ at 50% of the ground contact width is the rectangular ratio D. ₂ .

  From Table 1, it can be seen that the pneumatic radial tire of the example has a higher rectangular ratio than the pneumatic radial tire of the comparative example.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Carcass 5 Belt 6 Belt protective layer 7 Belt end 8 1/5 point 9 2/5 point A Shoulder area B Middle area C Center area W Belt full width

Claims (4)

A pair of bead portions and a pair of sidewall portions, and a tread portion connected to both sidewall portions, and a carcass extending in a toroid shape between the pair of bead portions to reinforce these portions, In a pneumatic tire in which a belt and a belt protective layer are sequentially arranged on the outer side in the tire radial direction of the crown portion,
The belt protection in the shoulder region from both ends of the belt to 1/5 point of the entire belt width, the intermediate region from the 1/5 point to 2/5 point, and the center region between the 2/5 points A pneumatic tire characterized in that the number of striking layers α, β, γ has a relationship of α ≧ γ> β.   The pneumatic tire according to claim 1, wherein the tread portion includes 3 to 4 main grooves extending in a tread circumferential direction on a tread surface.   The pneumatic tire according to claim 1, wherein the belt protective layer has three layers in at least a part of the shoulder region.   The pneumatic tire according to claim 3, wherein the belt protective layer has three layers in the shoulder region, one layer in the intermediate region, and two layers in the center region.

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