JP2010208502A - 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. A small groove 15 extending inwardly in the radial direction is formed in surface layer parts of the tread rubbers 6, 7 on the outer 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 the 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 suppress uneven wear that occurs 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 edge of the circumferential belt. It is to provide a tire that can be used.

  The first feature of the present invention is that a carcass (carcass 3) connecting 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), and a tire (pneumatic tire 1), which is a tread rubber on the outer side in the width direction from the width direction edge (width direction edge 4 a) of the circumferential belt. The gist is that a narrow groove (thin groove 15) extending radially inward is formed in the surface layer portion.

  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.

  However, as in the present invention, the tread rubber constituting the tread portion is substantially separated into the inner tread rubber arranged on the inner side in the width direction and the outer tread rubber arranged on the outer side in the width direction through the narrow groove, The narrow groove and the edge in the width direction of the circumferential belt are disposed at substantially the same position in the tire width direction. Therefore, the outer tread rubber portion on the outer side in the width direction than the narrow groove has a larger amount of expansion and contraction in the tire radial direction when the road surface is loaded, and the progress of wear is promoted with respect to the inner tread rubber on the inner side in the width direction than the narrow groove Is done. Here, conventionally, since the effect of the circumferential belt extends to the outer tread rubber, uneven wear easily progresses with the inner tread rubber. However, in the present invention, since the narrow groove is formed, the effect of the circumferential belt hardly reaches the outer tread rubber, and uneven wear of the inner tread rubber can be suppressed.

  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 narrow groove is formed in the boundary portion between the outer tread rubber and the inner tread rubber, the circumferential belt is less likely to reach the outer tread rubber. Uneven wear can be suppressed.

1 is a cross-sectional view in the width direction of a pneumatic 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 pneumatic tire of the example 1 of this invention in an Example. It is principal part sectional drawing of the pneumatic tire of the example 2 of this invention in an Example.

  Hereinafter, details of a pneumatic 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 pneumatic tire>
FIG. 1 is a cross-sectional view in the width direction of a pneumatic tire according to a first embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a 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 3a, the circumferential belt 4 and the inclined belt 5 of the carcass 3 are covered with tread rubber. The tread rubber is connected to the inner tread rubber 6 on the inner side in the width direction with the narrow groove 15 as a boundary. And the outer tread rubber 7 on the outer side in the width direction. A tread portion 10 is formed by the crown portion 3 a of the carcass 3, the circumferential belt 4, the inclined belt 5, and the tread rubbers 6 and 7, and side wall portions 11 are provided on the left and right sides of the tread portion 10. In addition, a bead portion 12 is formed near the bead core 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.

  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 the outer edges in the width direction of the outer tread rubber 7 on both the left and right sides, and the maximum width dimension W2 of the carcass 3 is the sidewall portion. 11 is a width dimension of the carcass 3 in a 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. W1 is preferably 125% or less with respect to W3.

<Configuration of narrow groove in tread part>
As shown in FIG. 2, a narrow groove 15 extending in the radial direction is formed in the surface layer portion of the tread portion 10 at a position in the width direction substantially the same as the width direction edge 4 a of the circumferential belt 4. The narrow groove 15 is set to a depth from the surface 10a of the tread portion 10 to the vicinity of the upper belt 14 of the inclined belt 5, and is formed continuously along the tire circumferential direction. The width dimension of the outer tread rubber 7 is W4, the width dimension of the inner tread rubber 6 is W5, and the width dimension of the narrow groove 15 is W6.

  Thus, the tread rubber constituting the tread portion 10 is substantially separated by the narrow groove 15 into the inner tread rubber 6 disposed on the inner side in the width direction and the outer tread rubber 7 disposed on the outer side in the width direction. . Further, the narrow groove 15 and the width direction edge 4a of the circumferential belt 4 are disposed at substantially the same position in the tire width direction.

<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, and toroidally. 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; And a narrow groove 15 extending radially inward in the surface layer portion of the tread rubber 6, 7 on the outer side in the tire width direction from the widthwise edge 4a of the circumferential belt 4. Is forming.

  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.

  However, as in the present invention, the tread rubber constituting the tread portion 10 is substantially divided into the inner tread rubber 6 disposed on the inner side in the width direction and the outer tread rubber 7 disposed on the outer side in the width direction by the narrow groove 15. The narrow groove 15 and the circumferential edge 4a of the circumferential belt 4 are separated and arranged at substantially the same position in the tire width direction. Therefore, the portion of the outer tread rubber 7 on the outer side in the width direction than the narrow groove 15 has a large amount of expansion and contraction in the tire radial direction when the road surface is loaded, and wears against the inner tread rubber 6 on the inner side in the width direction than the narrow groove 15. Progress is promoted. Here, conventionally, since the effect of the circumferential belt 4 has reached the outer tread rubber 7, uneven wear of the inner tread rubber 6 is likely to occur. However, in the present invention, the narrow groove 15 is formed. Therefore, the effect of the circumferential belt 4 is less likely to reach the outer tread rubber 7, and the outer tread rubber 7 wears before the inner tread rubber 6, thereby suppressing uneven wear of the inner tread rubber 6. Can do.

  (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 tire according to the conventional example and the present invention example was 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 order to verify uneven wear resistance, the pneumatic tire is assembled to the drive shaft of the tractor head, and the inner end of the inner tread rubber in the width direction outer end (i.e., the tread) after running an empty trailer for 50,000 m. The amount of uneven wear in the vicinity of the narrow groove) 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 has been found that the pneumatic tire according to the present invention is superior to the conventional example in both durability and uneven wear resistance.

      DESCRIPTION OF SYMBOLS 1 ... 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 ... narrow groove

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 rubber covering the crown portion of the carcass and the circumferential belt,
A tire characterized in that a narrow groove extending radially inward is formed in a surface layer portion of the tread rubber on the outer side in the width direction from an end edge in the width direction of the circumferential belt.   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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