JP5166331B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having a sipe engraved on the surface of a tread portion, and more particularly to a pneumatic tire that achieves both braking performance on an icy and snowy road surface and handling performance on a dry road surface.

  In general, pneumatic tires for snowy and snowy road surfaces use low-hardness rubber as the tread rubber, and have a structure in which sipes are formed on the ribs and blocks formed on the tread. The edge effect and the like of the edge are enhanced to improve the braking performance on the icy and snowy road surface (Patent Document 1).

JP-A-11-342706

  However, in the pneumatic tire described above, the rigidity of the ribs and blocks is reduced by sipe, and is easily deformed when a large load is applied during braking or cornering. In particular, during cornering, a large load is applied in the tire axial direction, and in particular, the end portions of the ribs and blocks in contact with the main grooves are deformed while falling down, so that the handling performance on a dry road surface is deteriorated.

  In order to solve this problem, it is conceivable to increase the rigidity of the ribs and blocks as a whole. To do. Thus, in a pneumatic tire, it has been difficult to achieve both braking performance on an icy and snowy road surface and handling performance on a dry road surface.

  In view of the above problems, an object of the present invention is to provide a pneumatic tire capable of improving handling performance on a dry road surface while maintaining braking performance on an icy and snowy road surface by sipe.

  In order to solve the above-described problems, a pneumatic tire according to the present invention includes a carcass layer, a belt layer disposed on a radially outer side of the carcass layer, and a tread portion disposed on a radially outer side of the belt layer. The tread portion has a plurality of land regions divided by a plurality of main grooves extending in the tire circumferential direction, and each land portion region is composed of a rib or a plurality of blocks. At least one sipe is formed, and a reinforcing layer is provided on the outer side in the radial direction of the belt layer and at the end in the width direction of each land portion region in contact with the main groove, and the width of the reinforcing layer is 3 mm or more The land area width is set to a range of 0.4 or less.

  That is, in the above configuration, a rigid layer is not disposed on the entire base of the ribs or blocks, but a reinforcing layer is not disposed in the center in the width direction of each land region, and each land portion in contact with the main groove is not disposed. By arranging the reinforcing layer only at the end in the width direction of the region, the rigidity of both ends of the land region is higher than the rigidity of the center of the land region.

  As a result, the deformation of the ribs and blocks is suppressed by the rigidity of the end portion in the width direction of the land region while securing the braking performance on the snowy and snowy road surface utilizing the characteristics of the sipe and the low hardness rubber in the central portion of the land region. Therefore, it is possible to obtain a pneumatic tire that achieves both braking performance on icy and snowy road surfaces and handling performance on dry road surfaces. In addition, the range of the land part area | region in a tire width direction is made between the both grounding ends of a tread part. Therefore, since the main groove is not formed at the end of the land portion region that is in contact with the ground contact end of the tread portion among the end portions of each land portion region, it is not necessary to dispose a reinforcing layer in particular.

  Here, the main groove refers to a linear or zigzag groove formed in the tire circumferential direction on the outer peripheral surface of the tread portion, and the tread portion is partitioned into a plurality of land portions by a plurality of main grooves.

  The width of the reinforcing layer is 3 mm or more and the land region width × 0.4 or less. When the width of the reinforcing layer is less than 3 mm, the effect of improving the handling performance on the dry road surface may not be recognized. Further, when the width of the reinforcing layer exceeds the land area width × 0.4, the rigidity of the land area becomes too high, and the braking performance on the icy and snowy road surface may be deteriorated. The reinforcing layer may be installed on the outer side in the radial direction of the belt layer, and is particularly preferably installed between the belt layer and the groove bottom of the main groove.

  What is necessary is just to make it the rigidity of a reinforcement layer be higher than the rigidity of the tread rubber which comprises the tread part which touches the outer surface. For example, when the tread portion has a cap / base two-layer structure, the tread rubber is composed of a base rubber constituting the base layer and a cap rubber constituting the cap layer. When the base layer is in contact with the outer surface of the reinforcing layer, the rigidity of the reinforcing layer is set to be higher than the rigidity of the base rubber. In addition, when the tread portion has a single-layer structure consisting only of a cap layer, or when the tread portion has a cap / base two-layer structure, if the cap layer is in contact with the outer surface of the reinforcing layer, the rigidity of the reinforcing layer Is higher than the rigidity of the cap rubber.

  As a material constituting the reinforcing layer, any material having higher rigidity than the base rubber or the cap rubber may be used. Specifically, rubber having higher hardness than base rubber or cap rubber can be used. In addition, as a material for the reinforcing layer, a composite material (for example, rubber with synthetic resin short fibers) in which a material having higher rigidity than the base rubber or cap rubber is blended is used, or a metal or synthetic resin having high rigidity is used. It is also possible to use a belt-like rubber-coated cord in which the cord is covered with rubber. In particular, it is preferable to use a rubber-coated cord in that the effect of increasing the rigidity and strength of the reinforcing layer is high.

  The reinforcement layers provided in each land region may all have the same rigidity, but the reinforcement layer existing outside the tire equator when the vehicle is mounted is the reinforcement layer existing inside the reinforcement layer. It can also be made higher than the rigidity of.

  That is, during cornering, a further load is applied to the outer side of the tire equator than to the inner side of the tire equator with the tire mounted on the vehicle. Therefore, by making the reinforcement layer on the outer side of the tire equator more rigid than the reinforcement layer existing on the inner side of the tire equator according to the load, it becomes possible to effectively suppress the deformation of the tread portion, and to dry Handling performance on the road surface can be further improved.

  In the present invention, the reinforcing layer that exists outside the tire equator when the vehicle is mounted refers to the end portion located on the inner side when the vehicle is mounted among the both ends in the width direction of the reinforcing layer. This refers to the reinforcing layer. Therefore, the reinforcing layer passing through the tire equator is not included in the reinforcing layer existing outside the tire equator when the vehicle is mounted.

  In the present invention, the tread portion is partitioned into a plurality of land regions by a plurality of main grooves extending in the tire circumferential direction, and sipes are formed on all the ribs and blocks constituting each land portion region, and in contact with the main grooves. Since a reinforcing layer is provided at the end in the width direction of each land area, and the width of the reinforcing layer is set to a range of 3 mm or more and the land area width x 0.4 or less, the braking performance on ice and snow road surfaces is improved, and the dry road surface is A pneumatic tire that achieves both improved handling performance can be obtained.

The top view which shows the tread pattern of the pneumatic tire in 1st embodiment of this invention. FIG. 1 is a cross-sectional view of the main part in the axial direction of the pneumatic tire. The top view which shows the aspect different from the tread pattern in FIG. The top view which shows the tread pattern of the pneumatic tire in 2nd embodiment of this invention. FIG. 4 is a cross-sectional view of the main part in the axial direction of the pneumatic tire.

[First embodiment]
FIG.1 and FIG.2 is a figure of the pneumatic tire which shows 1st embodiment of this invention. FIG. 1 is a plan view showing a tread pattern of a tread portion of a pneumatic tire, and FIG. 2 is a cross-sectional view of a main part in the axial (width) direction of the pneumatic tire. This pneumatic tire is a radial tire, and includes a pair of bead portions (not shown) and sidewall portions extending radially outward from the bead portions, a tread portion 1 that connects the upper ends thereof, and both ends along the inner periphery thereof are bead cores. And a carcass layer 2 which is folded and supported. A carcass cord extending in the radial direction is embedded in the carcass layer 2.

  A belt layer 3 is provided between the tread portion 1 and the carcass layer 2. The belt layer 3 is composed of at least two belt plies in which belt cords inclined in the opposite direction with respect to the tire equator C are embedded, and the other reinforcing structures are the same as in the case of a general radial tire. Since it is the same, detailed description is abbreviate | omitted.

  The tread portion 1 includes a cap / base structure composed of a cap layer 4 and a base layer 5 positioned inside the cap layer 4. A main layer formed in an annular shape in the tire circumferential direction on the outer peripheral surface of the cap layer 4. Four grooves 6 are formed. In the present embodiment, since the tread pattern is formed symmetrically in the tire width direction with the equator C interposed therebetween, only the tread portion 1 on one side from the tire equator C is shown in FIGS.

  In the tread portion 1, a plurality of land portion regions 7 partitioned by the main groove 6 and the ground contact end E are formed. That is, the land portion region 7 is a region surrounded by two adjacent main grooves 6, 6 or a region surrounded by the adjacent ground contact E and the main groove 6. In the present embodiment, the land region 7a through which the equator passes by the four main grooves 6, the land region 7b formed on both sides of the land region 7a, and the outside of the land region 7b. A total of five land areas 7 of land areas 7c are formed.

  As the pattern shape of the land region 7, the main groove 6 and the main groove 6 adjacent to each other or the rib shape formed by the division between the adjacent main groove 6 and the ground contact E can be used. It is also possible to divide the ribs into a plurality of block shapes by forming a plurality of lateral grooves 9 so as to connect the main groove 6 and the adjacent main groove 6 to the ground contact E. A sipe 11 is formed on each of the ribs 8 and the blocks 10 thus formed. Thereby, the braking performance of the pneumatic tire on the icy and snowy road surface can be ensured.

  A reinforcing layer 12 is disposed at the end in the width direction of the land region 7 in contact with the main groove 6. The reinforcing layer 12 is disposed inside the tread portion 1 and at the end in the width direction of each land portion region 7 so that the width is 3 mm or more and the land portion region width × 0.4 or less. The width of the land region 7 is the distance from the groove bottom end of the main groove 6 to the groove bottom end of the adjacent main groove 6 or from the grounding end E of the tread portion 1 to the groove bottom end of the adjacent main groove 6. It is taken as a distance.

  In the present embodiment, the reinforcing layer 12 is composed of a belt-like cord reinforcing rubber reinforced with a nylon 66 cord in which a plurality of reinforcing layers 12 are arranged in a line, and is arranged between the belt layer 3 and the tread portion 1. Is done. That is, since the base layer 5 is in contact with the outer surface of the reinforcing layer 12, the rigidity of the reinforcing layer 12 is required to be higher than that of the base rubber.

  In this way, by arranging the reinforcing layer 12 at the end in the width direction of the land portion region 7 in contact with the main groove 6, the rigidity of both end portions of the land portion region 7 is higher than the rigidity of the central portion of the land portion region 7. It becomes high and it becomes possible to suppress a deformation | transformation of the rib 8 or the block 10. FIG. As a result, it is possible to obtain a pneumatic tire that achieves both improved braking performance on icy and snowy road surfaces and improved handling performance on dry road surfaces.

  Although not shown in FIGS. 1 and 2, auxiliary grooves that connect sub-grooves and lateral grooves that are narrower than the main grooves 6 are usually formed in the tire circumferential direction. Further, the main groove 6 and the lateral groove 9 are not limited to having a constant width, and the groove width may be varied. A tread pattern is formed by combining various types and shapes of these grooves. As described above, when the main groove 6 is non-linear, the width of the land region 7 also varies. In this case, the width of the reinforcing layer 12 may be set so as to fall within a range of 3 mm or more and a land region width × 0.4 or less at each place in the tire circumferential direction.

  In the present embodiment, the sipe 11 employs a linear lateral sipe extending in the tire width direction. However, the present invention is not limited to this, and as another aspect of the tread pattern, for example, as shown in FIG. It is also possible to configure the region 7 by only the block 10 and to make a part of the sipe 11 a vertical sipe.

  It is also possible to form the sipe 11 so that the length direction is inclined with respect to the tire circumferential direction. Furthermore, the sipe 11 can be formed not only in a straight line but also in a waveform or a zigzag shape, or a wide part can be formed in the middle. In addition, although the sipe 11 in this embodiment is a closed sipe with both ends closed, it is not limited thereto, and may be an open sipe with at least one end opened.

[Second Embodiment]
4 and 5 are views of a pneumatic tire showing a second embodiment of the present invention, FIG. 4 is a plan view of a tread pattern, and FIG. 5 is a cross-sectional view of the main part in the axial (width) direction of the tire. Each is shown. In the present embodiment, in order to further improve the handling performance on the dry road surface, when a pneumatic tire is mounted on the vehicle, the rigidity of the reinforcing layer existing outside the vehicle from the tire equator is strengthened inside the vehicle. It is characterized by higher than the rigidity of the layer. The basic configuration of the tire and the arrangement of the reinforcing layer 12 are the same as those in the first embodiment.

  In the pneumatic tire in the present embodiment, the tread pattern is asymmetric on the left and right (tire width direction) with the tire equator C as the center. Specifically, in a state where a pneumatic tire is mounted on the vehicle, land regions 7f and 7g are formed on the vehicle outer side from the tire equator C, and the land region 7e passes through the tire equator C and is closer to the vehicle inner side. The land portion region 7d is formed on the vehicle inner side than the land portion region 7e.

  Of the land regions 7d to 7g, the reinforcing layer 12a provided in the land regions 7f and 7g exists outside the tire equator C when the vehicle is mounted. On the other hand, the reinforcing layer 12b formed in the land portion regions 7d and 7e exists inside the reinforcing layer 12a. In the present embodiment, the reinforcing layer 12a is set to have higher rigidity than the reinforcing layer 12b. The rigidity of the reinforcing layers 12a and 12b can be adjusted, for example, by changing the number of cord ends included in the reinforcing layers 12a and 12b (the number of embedded cords per 50 mm width of the reinforcing layer).

  Thus, since a large load is applied to the vehicle outer side than the tire equator during cornering, the rigidity of the reinforcing layer 12a existing in this region is made higher than the rigidity of the reinforcing layer 12b existing inside the vehicle including the tire equator C. Thus, the handling performance on the dry road surface can be further improved.

  In the present embodiment, the tread pattern is provided with a rib pattern 8 only on the vehicle outer side than the equator C for the purpose of balancing cornering performance and braking performance on an icy and snowy road surface, and the block pattern 10 is provided on the vehicle inner side including the equator C. An asymmetrical pattern with only a single is used. However, the present invention is not limited thereto, and the handling performance on the dry road surface can be further improved by making the rigidity of the reinforcing layer existing outside the vehicle from the equator C higher than the rigidity of the other reinforcing layers even in the symmetric pattern. Of course.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to these Examples, unless the summary is exceeded.
[Production of tires]
A radial tire was produced with the tread pattern shown in FIGS. Specifically, as shown in Table 1, radial tires were manufactured by variously changing the ratio (α / β) of the width α of the reinforcing layer 12 to the width β of the land region 7 (Examples 1-3, Comparative examples 2 and 3). For comparison, a tire without a reinforcing layer (Comparative Example 1) and a tire (Comparative Example 4) in which one reinforcing layer was laminated over the entire tread portion on the outer surface of the belt layer were prepared. The reinforcing layer used was a rubber-coated cord in which nylon 66 cord having a structure 1260d / 2 was covered with rubber so that the number of cord ends was 40/50 mm.

  Further, a radial tire was produced with the tread pattern shown in FIGS. Specifically, as shown in Table 2, the ratio (α / β) of the width α of the reinforcing layer 12 to the width β of the land region 7 is constant at 0.3, and two types of reinforcing layers having different rigidity are provided. A radial tire was manufactured in combination (Examples 4 and 5). That is, a cord made of nylon 66 having a structure 1260d / 2 is used as a cord, and a rubber-coated cord (configuration A) having a cord end number of 40/50 mm and a rubber-coated cord having a cord end number of 60/50 mm (configuration B) The reinforcing layer was formed using two types of rubber-coated cords. The tire size was 205 / 55R16 in all cases.

[Evaluation test]
(1) Brake performance on icy and snowy road surface Tires are mounted on a real vehicle (domestic 2000cc class FF sedan), run on icy and snowy road surface at the air pressure specified by the vehicle, ABS braking distance from 40 km / h is measured, and sample 1 The braking distance is expressed as an index when the braking distance is 100. The larger the value, the better the braking performance.
(2) The tires were mounted on a real vehicle (domestic 2000cc class FF sedan), run on a dry road surface with the air pressure specified by the vehicle, performed straight running, turning, braking, etc., and evaluated by a sensory test of the driver . In addition, evaluation is made into a 10-point perfect score, and it shows that it is excellent in the handling performance in a dry road surface, so that a numerical value is large.

[Evaluation results]
Tables 1 and 2 show the evaluation results. From Table 1, Examples 1 to 3 in which the reinforcing layer width is set to a range of 3 mm or more and the land region width × 0.4 or less are compared with Comparative Example 1 in which no reinforcing layer is provided. The dry road surface handling performance (hereinafter abbreviated as handling performance) is improved while maintaining the braking performance (hereinafter abbreviated as braking performance). On the other hand, Comparative Example 2 in which the reinforcing layer width is smaller than 3 mm has a small reinforcing effect by the reinforcing layer, and Comparative Examples 3 and 4 in which the reinforcing layer width is larger than the land portion region width × 0.4 is in the land portion region. As a result, the rigidity of the vehicle became too high and the braking performance decreased.

  Moreover, from Table 2, the handling performance of Comparative Example 5 was higher than that of Comparative Example 1 because the tread pattern was changed even though the reinforcing layer was not formed as in Comparative Example 1. In Example 4 in which all of the reinforcing layers have the same configuration (Configuration A) as in Table 1 and the reinforcing layer width is set to 3 mm or more and the land region width × 0.4 or less, Comparative Example 5 while maintaining the braking performance. Handling performance has been improved.

  Further, among the reinforcing layers, the reinforcing layer that exists outside the tire equator when the vehicle is mounted is configured as B having high rigidity, and the reinforcing layer that is present inside the configuration is configured as A. In addition, handling performance has been improved. This makes it possible to further improve the handling performance by making the rigidity of the reinforcing layer present outside the tire equator when the vehicle is mounted higher than the rigidity of the reinforcing layer existing inside the tire equator. Became clear.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Carcass layer 3 Belt layer 4 Cap layer 5 Base layer 6 Main groove 7 Land area 8 Rib 9 Horizontal groove 10 Block 11 Sipe 12 Reinforcement layer C Tire equatorial plane E Ground contact edge

Claims (4)

A carcass layer; a belt layer disposed radially outward of the carcass layer; and a tread portion disposed radially outward of the belt layer, wherein the tread portion includes a plurality of main grooves extending in a tire circumferential direction. A plurality of land areas divided by the ribs, each land area being composed of a rib or a plurality of blocks, at least one sipe is formed for each of the ribs and blocks, and radially outward of the belt layer. In addition, a reinforcing layer is provided at the end in the width direction of each land portion region in contact with the main groove, and the width of the reinforcing layer is set to a range of 3 mm or more and a land portion region width × 0.4 or less. Pneumatic tire characterized by. 2. The pneumatic tire according to claim 1, wherein a rigidity of a reinforcement layer existing outside the tire equator among the reinforcement layers is higher than a rigidity of a reinforcement layer existing inside the tire equator. . 3. The pneumatic tire according to claim 1, wherein the rigidity of the reinforcing layer is higher than the rigidity of the tread rubber constituting the tread portion in contact with the outer surface thereof. The pneumatic tire according to claim 1, wherein the reinforcing layer includes a plurality of cords.

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