JP2012020672A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire that reduces rolling resistance without losing durability of the tire.SOLUTION: The tire 1 includes: a pair of beads 3; a pair of sidewalls 4 extending from the bead 3 to the outside in a tire radial direction; and a tread 5 extending across both of the sidewalls. A large number of blocks 10 are formed by dividing with a plurality of grooves 9 on the sidewall 4.

Description

  The present invention relates to a tire having a pair of bead portions, a pair of sidewall portions extending outward in the tire radial direction from the bead portions, and a tread portion extending between both sidewall portions. It is intended to reduce rolling resistance without lowering.

  The pneumatic tire needs to support a considerable weight, and the sidewall portion is repeatedly deformed when the tire is loaded and rolled. At this time, the rubber constituting the sidewall portion is deformed and generates heat, so that energy loss occurs in the sidewall portion. Due to such energy loss, the rolling resistance increases, so that the fuel consumption decreases due to the increased rolling resistance.

  In recent years, demand for tires with a large flatness ratio has increased due to demands for higher speeds and lower floors of vehicles. In such a tire, the load applied to the sidewall portion of the tread portion at the time of rolling of the tire load increases, so that the compressive deformation in the tire radial direction increases at the sidewall portion. Therefore, the problem regarding the reduction in fuel consumption due to the increase in rolling resistance as described above becomes particularly significant.

  As a solution to this problem, it has been proposed to thin the sidewall portion of the tire. This is because if the sidewall portion is thinned, even if the rubber in the sidewall portion is deformed during rolling with tire load, energy loss due to the rubber deformation is reduced, so that rolling resistance can be reduced.

  However, as described above, when the sidewall portion is thinned, there is a certain effect for reducing the rolling resistance, but as the sidewall portion is thinned, its trauma resistance is lowered, and as a result, the tire There is a risk that the resistance to trauma may be reduced.

  Accordingly, an object of the present invention is to provide a tire in which rolling resistance is reduced without deteriorating the trauma resistance of the tire by optimizing the configuration of the sidewall portion.

  In order to achieve the above object, a tire according to the present invention has a pair of bead portions, a pair of sidewall portions extending outward from the bead portion in the tire radial direction, and a tread portion extending between both sidewall portions. The sidewall portion is formed by partitioning a large number of blocks with a plurality of groove portions.

  Moreover, it is preferable that the groove width of the groove part which divides and forms many blocks exists in the range of 1.0-3.0 mm.

  Furthermore, it is preferable that the deepest position of the groove part which partitions and forms many blocks exists in the position spaced apart by 1.0-3.0 mm toward the outer side of the tire from the carcass.

  Furthermore, it is preferable that the groove bottom of the groove part which partitions and forms many blocks has a curvature. At this time, the curvature of the groove bottom of the groove portion is 0.5 mm or more and preferably 50% or less of the groove width.

  In addition, the groove width of the large number of blocks is preferably larger on the outer side in the tire radial direction of the sidewall part than on the inner side in the tire radial direction of the sidewall part.

  In addition, it is preferable that the groove widths of the large number of blocks gradually increase toward the outer side in the tire radial direction.

  Moreover, it is preferable that the diameter of many blocks is 20 mm or less. Here, the “block diameter” refers to an average value of the block diameters.

  According to the present invention, it is possible to provide a tire with reduced rolling resistance without degrading the trauma resistance of the tire by partitioning and forming a large number of blocks with a plurality of grooves in the sidewall portion. Become.

1 is a half cross-sectional view in a tire width direction of a typical tire according to the present invention. It is the figure which looked at the tire shown in Drawing 1 from the tire width direction outside. It is an enlarged view of many blocks provided in the side wall part of the other tire according to this invention. It is an enlarged view of many blocks provided in the side wall part of the other tire according to this invention. It is an enlarged view of many blocks provided in the side wall part of the other tire according to this invention. It is the figure which showed the influence which the diameter and groove width of many blocks have on rolling resistance. It is the figure which showed the influence which the groove width between many blocks has on cut resistance

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a half sectional view in the tire width direction of a typical tire according to the present invention. FIG. 2 is a view of the tire shown in FIG. 1 as viewed from the outside in the tire width direction. FIG. 3 is an enlarged view of a large number of blocks provided in a sidewall portion of another tire according to the present invention. FIG. 4 is an enlarged view of a large number of blocks provided in a sidewall portion of another tire according to the present invention. FIG. 5 is an enlarged view of a large number of blocks provided in a sidewall portion of another tire according to the present invention. In addition, the code | symbol E in a figure has shown the tire equator surface.

The tire 1 shown in FIGS. 1 and 2 spans between a pair of bead portions 3 in which a bead core 2 is embedded, a pair of sidewall portions 4 extending from the bead portion 3 outward in the tire radial direction, and both sidewall portions 4. It includes a tread portion 5 that extends. Further, a belt layer 8 made of a rubber-covered cord extending in the tire circumferential direction is provided on the outer periphery of the crown portion 7 of the carcass 6 extending in a toroidal shape between the pair of bead portions 3. Further, by providing a plurality of groove portions 9 in the sidewall portion 4, a large number of hexagonal blocks 10 are defined. When such a configuration is adopted and a large number of block land portions 10 are provided in the sidewall portion 4, even if the rubber constituting the sidewall portion 4 is deformed at the time of tire load rolling, the deformation force is generated between adjacent blocks. Since it is divided, the energy loss at the time of deformation of the sidewall portion 4 is reduced, the rolling resistance is effectively reduced, and the fuel consumption can be improved. Further, since the groove portion 9 is provided in the sidewall portion 4, it is possible to advantageously suppress a decrease in the damage resistance as compared with a conventional tire having a configuration in which the sidewall portion is thinned as a whole. .
Note that the shape of the block 10 provided in the sidewall portion 4 is not limited to the hexagonal shape shown in FIG. 2, and can be any other block shape, for example, as shown in FIGS. 3 and 4. Thus, it is possible to use a triangular block 10A, or a configuration in which an octagonal block 10B and a rectangular block 10C are combined as shown in FIG. Further, as shown in FIGS. 3 and 4, the adjacent pattern between the blocks 10A can be arbitrarily changed.

  Further, as shown in FIG. 1, a large number of blocks 10 are virtual lines extending from the point intersecting the tire equator of the innermost belt layer 8 to the outermost end position in the tire radial direction in the tire width direction cross section. It is preferable to be disposed in a region between the intersection position with the outer surface of the sidewall portion 4 and the tire maximum width position 11. In general, in the region between the above-described intersection position of the sidewall portion 4 and the tire maximum width position 11, the energy loss accompanying tire load rolling is large, which affects the increase in rolling resistance. In view of that, it is preferable to provide a large number of blocks 10 on the sidewall portion 4 in the above-described range from the viewpoint of effectively reducing rolling resistance.

  Furthermore, from the viewpoint of appropriately dividing the deformation force between the adjacent blocks 10 at the time of tire load rolling, the groove width of the groove portion 9 that partitions and forms a large number of blocks 10 is in the range of 1.0 to 3.0 mm. It is preferable. Furthermore, from the same viewpoint, it is preferable that the deepest position of the groove portion that defines a large number of blocks is located at a position separated from the carcass in the range of 1.0 to 3.0 mm toward the outside of the tire.

  In addition, it is preferable that the groove bottom of the groove part which partitions and forms many blocks has a curvature. This is because by providing a curvature at the groove bottom of the groove portion 9, it is possible to suppress the occurrence of cracks at the groove bottom of the groove portion 9 when repeatedly deforming during tire load rolling. . At this time, from the viewpoint of effectively suppressing cracks at the groove bottom of the groove part 9, the curvature of the groove bottom of the groove part 9 is preferably 0.5 mm or more and 50% or less of the groove width.

  In addition, although not shown, the groove width of the large number of blocks 10 is preferably larger on the outer side in the tire radial direction of the sidewall portion 4 than on the inner side in the tire radial direction of the sidewall portion 4. This is because the energy loss in the sidewall portion at the time of tire load rolling is larger on the outer side in the tire radial direction of the sidewall portion 4 than on the inner side in the tire radial direction of the sidewall portion 4, and corresponding blocks corresponding thereto. This is because increasing the distance between 10 and improving the performance of dividing the deformation force is appropriate for reducing the rolling resistance.

  Moreover, it is preferable that the groove width of many blocks 10 is gradually increased toward the outer side in the tire radial direction. This is because energy loss in the sidewall portion during rolling of the tire load gradually increases from the inner side in the tire radial direction of the sidewall portion 4 toward the outer side in the tire radial direction. This is because it is appropriate for gradually reducing the rolling resistance to gradually improve the performance of dividing the deformation force by gradually increasing the distance.

  Furthermore, the diameter of the large number of blocks 10 is preferably 20 mm or less. Because, when the diameter of the block 10 exceeds 20 mm, when the rubber constituting the sidewall portion 4 is deformed, the block 10 is also deformed following the deformation, and this deformation force is effective between adjacent blocks. This is because the energy loss at the time of deformation of the sidewall portion 4 is increased without being divided into two, and the rolling resistance is not effectively reduced.

  The above description shows only a part of the embodiment of the present invention, and these configurations can be combined alternately or various changes can be made without departing from the gist of the present invention.

  Next, a conventional tire (conventional tire 1) that does not have a large number of blocks in the sidewall portion and a tire (example tires 1 to 4) according to the present invention in which a large number of blocks are arranged in the sidewall portion are respectively prototyped Since the running performance was evaluated, it will be described below. The conventional tire and the example tires 1 to 4 are tires for heavy loads for buses and trucks having a tire size of 11R22.5. Each of these tires has the specifications shown in Table 1.

  These conventional tires and example tires 1 to 4 were attached to rims of 7.50 × 22.5 to form tire wheels, and an air pressure of 900 kPa (relative pressure) was applied to evaluate rolling resistance and damage resistance. .

  The rolling resistance is determined by running the tire wheel on a drum tester having a drum diameter of 1.7 m under the conditions of speed: 80 km / h and tire load load of 24.5 kN, and the axial force that supports the tire wheel is Evaluation was made by measuring. At this time, the numerical value of rolling resistance is calculated by comparing the numerical value in the conventional tire as 100 and compared with Example tires 1 to 4, and the smaller the numerical value, the lower the rolling resistance.

  As for the trauma resistance, the tire wheel is mounted on a vehicle, a tire load of 24.5 kN is applied, a protrusion that damages the sidewall portion is stepped on the test road, and the tire breaks down due to the damage. The number of repetitions was evaluated by comparing the example tire with the conventional tire. In addition, the numerical value of durability is the numerical value which converted that in a conventional example tire as 100, and compared with Example tires 1-4, and it shows that durability is improving, so that this numerical value is small.

  As a result, the trauma resistance of Example tires 1 to 4 was equivalent to that of the conventional tires. Moreover, compared with the conventional tire, the rolling resistance of Example tires 1 to 4 was improved, and in particular, the rolling resistance of Example tires 3 and 4 was significantly improved.

  As is apparent from the above, according to the present invention, a tire having a reduced rolling resistance without impairing the durability of the tire by providing grooves in the sidewall and partitioning a large number of blocks. It became possible to provide.

DESCRIPTION OF SYMBOLS 1 Tire 2 Bead core 3 Bead part 4 Side wall part 5 Tread part 6 Carcass 7 Carcass crown part 8 Belt layer 9 Groove part 10, 10A, 10B, 10C Block 11 Tire maximum width position

Claims (8)

In a tire having a pair of bead portions, a pair of sidewall portions extending outward in the tire radial direction from the bead portions, and a tread portion extending between both sidewall portions,
A tire comprising a plurality of blocks defined by a plurality of grooves on the sidewall portion.   2. The tire according to claim 1, wherein a groove width of a groove portion defining the plurality of blocks is in a range of 1.0 to 3.0 mm.   3. The tire according to claim 1, wherein a deepest position of a groove portion defining the plurality of blocks is located at a position spaced apart by 1.0 to 3.0 mm from the carcass toward the outside of the tire.   The tire according to any one of claims 1 to 3, wherein a groove bottom of a groove portion that partitions and forms the plurality of blocks has a curvature.   The tire according to claim 4, wherein the curvature is 0.5 mm or more and 50% or less of the groove width.   The tire according to any one of claims 1 to 5, wherein a groove width of the plurality of blocks is larger on an outer side in the tire radial direction of the sidewall portion than on an inner side in the tire radial direction of the sidewall portion.   The tire according to claim 6, wherein the groove width of the plurality of blocks is gradually increased toward the outer side in the tire radial direction.   The tire according to any one of claims 1 to 7, wherein the plurality of blocks have a diameter of 20 mm or less.

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