JP2010208505A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire suppressing any partial wear generated between a part arranged on the outer radial side of a circumferential belt and a part arranged on the outer side in the width direction from an edge of the circumferential belt of a tread part. <P>SOLUTION: The pneumatic tire 1 comprises a carcass 3 for connecting in a toroidal manner a pair of annular bead cores 2, 2 arranged separate from each other in the tire width direction, a circumferential belt 4 having a plurality of cords extending along the tire circumferential direction, and arranged on the outer radial side of a crown part 3a of the carcass 3, and tread rubbers 6, 7 for covering the crown part 3a of the carcass 3 and the circumferential belt 4. The thickness in the radial direction of the outer tread rubber 7 on the outer side in the width direction from an edge 4a in the width direction of the circumferential belt 4 is set to be smaller than that of the inner tread rubber 6 on the inner side in the width direction from the edge 4a in the width direction of the circumferential belt 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire, and more particularly to a heavy duty tire such as a truck or a bus.

  Conventionally, in heavy-duty tires such as trucks and buses, a circumferential belt or the like may be disposed outside the diameter of the crown portion of the carcass for the purpose of enhancing the rigidity of the tread portion. This circumferential belt is set to have the highest rigidity among the belts arranged in the tread portion, and has a great effect of suppressing the tread rubber and the carcass to the inside of the diameter, which is called a so-called effect. When the road surface load is applied to the outer tread portion arranged on the outer side in the width direction with respect to the edge in the width direction, the amount of expansion and contraction in the radial direction becomes larger than the inner tread portion at the position in the width direction corresponding to the circumferential belt. For this reason, there is a possibility that separation may occur in the vicinity of the end portion in the width direction of the circumferential belt, and as a countermeasure against this, a tire that employs a wavy belt that extends in the tire circumferential direction and has a cord formed in a wavy or zigzag shape. Has been developed (see, for example, Patent Document 1).

JP 2004-345437 A

  However, since the above-described corrugated belt has uniform rigidity up to the end in the width direction, the inner tread portion disposed on the outer diameter side of the circumferential belt and the outer side in the width direction than the edge of the circumferential belt. The difference in rigidity between the outer tread portion and the outer tread portion made remarkable, and uneven wear generated in the outer tread portion progressed to the inside, resulting in large uneven wear.

  An object of the present invention is to provide uneven wear between an inner tread portion disposed on the outer diameter side of the circumferential belt and an outer tread portion disposed on the outer side in the width direction than the width direction edge of the circumferential belt. It is in providing the tire which can suppress this.

  The first feature of the present invention is that a carcass (carcass 3) that connects a pair of annular bead cores (bead cores 2) spaced apart in the tire width direction in a toroidal shape, and a plurality of portions extending along the tire circumferential direction. A circumferential belt (circumferential belt 4) provided with a cord and disposed on a radially outer side of a crown portion (crown portion 3a) of the carcass, and a tread rubber covering the crown portions of the carcass and the circumferential belt (Inner tread rubber 6, outer tread rubber 7), a tire (pneumatic tire 1), and an outer tread outside in the width direction with respect to the width direction edge (width direction edge 4a) of the circumferential belt. The gist is to make the radial thickness of the rubber smaller than the inner tread rubber on the inner side in the width direction than the end edge in the width direction of the circumferential belt.

  Normally, when a belt having a wavy belt or a high extension cord is adopted as the circumferential belt, these belts have uniform and high rigidity up to the end in the width direction of the belt. There is a large difference in rigidity between the inner tread portion arranged on the outer side of the belt and the outer tread portion arranged on the outer side in the width direction than the circumferential belt, and the degree of wear on the outer tread portion is increased. There was a trend.

  Here, in the present invention, since a stepped portion that is recessed radially inward is formed at the end in the width direction of the tread portion, the tread rubber is substantially separated into the inner tread rubber and the outer tread rubber by the stepped portion. be able to. As a result, the wear of the outer tread rubber is suppressed, and the road surface is reliably clipped by the inner tread rubber. As a result, uneven wear of the inner tread rubber can be prevented.

  Another feature is that the width dimension W3 of the circumferential belt (circumferential belt 4) is set to 70 to 90% with respect to the maximum width dimension W2 of the carcass (carcass 3).

  The other feature is that an inclined belt (inclined belt 5) provided with a plurality of cords extending incline with respect to the tire circumferential direction is disposed outside the diameter of the circumferential belt (circumferential belt 4). And

  According to the tire according to the present invention, since the step portion recessed inward in the diameter is provided at the end in the width direction of the tread portion, the wear of the outer tread rubber is suppressed, and the road surface is reliably clipped with the inner tread rubber, thereby obtaining the result. Therefore, uneven wear of the inner tread rubber can be prevented.

1 is a cross-sectional view in the width direction of a tire according to an embodiment of the present invention. It is sectional drawing to which the principal part of FIG. 1 was expanded. It is principal part sectional drawing of the tire of the example 1 of this invention in an Example. It is principal part sectional drawing of the tire of this invention example 2 in an Example.

  Hereinafter, details of a tire according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

<Schematic configuration of tire>
FIG. 1 is a cross-sectional view in the width direction of a tire according to a first embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the main part of FIG.

  As shown in FIG. 1, a pneumatic tire 1 includes a pair of annular bead cores 2 and 2 that are spaced apart from each other in the tire width direction, and these bead cores 2 and 2 are connected in a toroidal shape to form a tire skeleton. A carcass 3, a circumferential belt 4 disposed on the radially outer side of the crown portion 3 a that is the central portion in the width direction of the carcass 3, and a two-layer inclined belt 5 disposed on the radially outer side of the circumferential belt 4. And.

  The crown portion 3a, the circumferential belt 4 and the inclined belt 5 of the carcass 3 are covered with tread rubber to constitute a tread portion 10. The tread rubber is divided into the inner tread rubber 6 disposed on the inner side in the width direction and the outer tread rubber disposed on the outer side in the width direction with the width direction edge 4a of the circumferential belt 4 as a boundary. 7 A bead portion 12 is formed in the vicinity of the bead core 2 on the inner diameter side of the sidewall portion 11. And the said carcass 3 has the folding | returning part 3b which extends | folds by bend | folding back radially outward after winding the bead core 2 from the tire width direction inner side to the outer side.

  Here, a stepped portion 15 that is recessed radially inward is formed at the end in the width direction on the surface of the tread portion 10. Specifically, since the radial thickness of the outer tread rubber 7 is smaller (thinner) than the radial thickness of the inner tread rubber 6, the bottom wall portion 15 a that is the surface of the outer tread rubber 7 and A step portion 15 having a substantially L-shaped cross section is formed by the vertical wall portion 15b rising radially outward from the width direction inner end of the bottom wall portion 15a. And the width direction edge 4a of the circumferential belt 4 and the vertical wall portion 15b of the step portion 15 are arranged at substantially the same position in the tire width direction.

  In addition, as shown in FIG. 1, the inclined belt 5 includes a lower belt 13 disposed inside the diameter and an upper belt 14 disposed outside the diameter of the lower belt 13, and the upper belt The width dimension of 14 is formed smaller than the width dimension of the lower belt 13. The inclined belt 5 has a plurality of cords extending obliquely with a predetermined inclination angle with respect to the tire circumferential direction, and the inclination angles of the cords in the upper belt 14 and the lower belt 13 are set so as to cross each other. Has been. Furthermore, the circumferential belt 4 is provided with a plurality of cords extending in the tire circumferential direction. When the circumferential belt 4 and the inclined belt 5 are compared, the rigidity of the circumferential belt 4 is set high. The circumferential belt 4 is a belt having a wave belt or a high extension cord. Moreover, the tire diameter growth rate at the time of internal pressure in the vicinity of the width direction edge 4a of the circumferential belt 4 is preferably 0.5% or less, and more preferably 0.3% or less.

  As shown in FIG. 1, the width dimension W1 of the tread portion 10 is the width between widthwise outer edges of the left and right sides of the inner tread rubber 6, and the maximum width dimension W2 of the carcass 3 is the sidewall portion 11. This is the width dimension of the carcass 3 at the portion having the largest width dimension. A width dimension W3 of the circumferential belt 4 is set to 70 to 90%, preferably 80 to 90%, with respect to a maximum width dimension W2 of the carcass 3.

<Configuration of the step in the tread>
2, the width dimension of the outer tread rubber 7 (that is, the width dimension of the bottom wall portion 15a of the step portion 15) is W4, and the height in the radial direction of the vertical wall portion 15b of the step portion 15 is H. It is.

As described above, the bottom wall portion 15a of the step portion 15 formed at the end portion in the width direction of the tread portion 10 is formed to have a height that is lower than the inner tread rubber 6 by the height H on the inner diameter side. . The radial height H of the vertical wall portion 15b is preferably 3 mm or more.
The width dimension (W1 + W4) of W1 and W4 is preferably 125% or less with respect to W3.

<Operation effect>
(1) A pneumatic tire 1 according to an embodiment of the present invention extends along a tire circumferential direction with a carcass 3 that connects a pair of annular bead cores 2 and 2 that are spaced apart in the tire width direction, in a toroidal shape. A circumferential belt 4 provided with a plurality of cords and disposed on the outer diameter side of the crown portion 3a of the carcass 3, and the tread rubber 6 covering the crown portion 3a of the carcass 3 and the circumferential belt 4; 7, wherein the radial thickness of the outer tread rubber 7 outside the width direction edge 4 a of the circumferential belt 4 is set to the width direction end of the circumferential belt 4. By making the inner tread rubber 6 smaller than the inner tread rubber 6 on the inner side in the width direction than the edge 4a, a step portion 15 recessed radially inward is formed at the end in the width direction on the surface of the tread portion 10.

  Usually, when a belt having a wavy belt or a high extension cord is adopted as the circumferential belt 4, these belts have uniform and high rigidity up to the end in the width direction of the belt. There is a large difference in rigidity between the inner tread portion arranged on the outer side of the directional belt 4 and the outer tread portion arranged on the outer side in the width direction of the circumferential belt 4, and wear of the inner tread portion is increased. The degree increases.

  Here, in the present invention, since the step portion 15 that is recessed radially inward is formed at the end in the width direction of the tread portion 10, the tread rubber is formed by the step portion 15 into the inner tread rubber 6 and the outer tread rubber 7. Can be substantially separated. As a result, the wear of the outer tread rubber 7 is suppressed, and the road surface is reliably clipped by the inner tread rubber 6. As a result, uneven wear of the inner tread rubber 6 can be prevented.

  (2) The width dimension W3 of the circumferential belt 4 is set to 70 to 90% with respect to the maximum width dimension W2 of the carcass 3. Thus, by forming the circumferential belt 4 wide, the expansion and contraction of the tire diameter at the end in the width direction of the tread portion 10 at the time of road load is suppressed, and the durability of the circumferential belt 4 is improved and the separation is performed. It can be effectively prevented.

  (3) An inclined belt 5 provided with a plurality of cords that are inclined and extended with respect to the tire circumferential direction is disposed on the outer diameter side of the circumferential belt 4. For this reason, the rigidity of the tread portion 10 can be further improved.

  It should not be understood that the description and the drawings, which form part of the disclosure of the above-described embodiments, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in each of the above-described embodiments, the inclined belt 5 has a two-layer structure of the lower belt 13 and the upper belt 14, but may be configured to have three or more layers.

  Hereinafter, the present invention will be described in more detail through examples.

  The pneumatic tires according to the conventional example, the comparative example, and the example of the present invention were assembled to a rim wheel having a tire size of 495 / 45R22.5 and a rim size of 17 inches wide. The durability and the amount of uneven wear were verified with the internal pressure of the pneumatic tire set to 900 kPa. The structure of the pneumatic tire is shown in detail in Table 1. Moreover, the structure and each dimension of the tread part of the pneumatic tire which concerns on Example 1 of this invention are shown in FIG. 3, The structure and each dimension of the tread part of the pneumatic tire which concerns on Example 2 of this invention are shown in FIG. Show.

  First, as a verification of durability, the pneumatic tire was run at a distance of 100,000 m under a load of 8500 kg and a speed of 80 km / h, and then the number of cords of belt separation and circumferential belt was determined. confirmed.

  In addition, as a verification of uneven wear resistance, the amount of uneven wear at the outer end in the width direction of the inner tread rubber after the pneumatic tire was assembled on the drive shaft of the tractor head and the free trailer was pulled to travel 50,000 m It was confirmed. These results are shown in Table 2. In addition, each index | exponent means that the pneumatic tire which concerns on the prior art example 1 is 100 of the reference | standard, and the one where a smaller index | exponent is a favorable result.

  From the above results, it was found that the pneumatic tire according to the present invention is superior to the conventional example and the comparative example in both durability and uneven wear resistance.

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire 2 ... Bead core 3 ... Carcass 3a ... Crown part 4 ... Circumferential belt 4a ... Edge in the width direction 5 ... Inclined belt 6 ... Inner tread rubber (tread rubber)
7 ... Outer tread rubber (tread rubber)
10 ... tread part 15 ... step part

Claims (2)

A carcass that connects a pair of annular bead cores spaced apart in the tire width direction in a toroidal shape and a plurality of cords that extend along the tire circumferential direction are provided, and are disposed outside the crown portion of the carcass. A circumferential belt, and a tread portion in which the crown portion of the carcass and the circumferential belt are covered with a tread rubber,
The radial thickness of the outer tread rubber on the outer side in the width direction than the end edge in the width direction of the circumferential belt is made smaller than the inner tread rubber on the inner side in the width direction than the end edge in the width direction of the circumferential belt. Tire.   The tire according to claim 1, wherein a width dimension of the circumferential belt is set to 70 to 90% with respect to a maximum width dimension of the carcass.

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