JP2011042226A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire improved in cornering performance. <P>SOLUTION: The pneumatic tire has a block group including a plurality of blocks having a polygonal surface on a tread of the tire. When a reference pitch length of the block in the block group is P (mm), a width of the block group is W (mm), the number of the blocks existing in a reference region of the block group sectioned by the reference pitch length P and the width W is a (pieces), and a negative ratio in the reference region is N (%), the block number density S per unit actual ground area of the block group given by a/(P×W×(1-N/100)) is in the range of 0.003-0.04 (piece/mm<SP>2</SP>). Further, a sheet of organic fibers is buried in a tread rubber of the tread part in the range of 50% or more of the unit actual ground area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire having a group of blocks each including a block of pillars having a polygonal bottom surface on a tread of the tire.

  Conventionally, in a pneumatic tire, as in Patent Document 1, for example, by improving the edge effect, a block having a main groove or a lateral groove is provided for the purpose of improving driving, braking, and turning performance on a wet road surface, an ice surface, and the like. In general, it is widely performed to form fine sections and add sipes in the formed blocks.

Japanese Patent Laid-Open No. 2001-191739

In the conventional pneumatic tire as described above, each block is formed relatively large for the purpose of improving the running performance by securing a large contact area, so that the water film is efficient in the central area of the block. It was not removed well, and this was also a factor that hindered the improvement of running performance on wet road surfaces.
In addition, when the sipe is provided in the block, the edge effect is improved, but the rigidity of the block portion is lowered by the sipe, and in particular, the rigidity at the time of turning of the vehicle is insufficient. In other words, if the block part near the outside of the vehicle falls when the vehicle turns, the grounding property deteriorates, and the low-rigidity block tends to bend and deform, resulting in a small cornering force and steering stability. As a result, there has been a problem that the vehicle performance becomes low, and it has been difficult to obtain sufficient traveling performance commensurate with the recent improvement in vehicle performance. In particular, when improving the performance on wet surfaces, it is necessary to provide more sipes in the block under the demand for higher driving, braking and turning performance. It becomes more prominent.

  Therefore, the present invention has an object to solve these problems, and an object of the present invention is to provide a pneumatic tire with improved steering stability by optimizing the structure of the block of the tread portion. It is to provide.

  The inventors have made extensive studies in order to solve the above-mentioned problems. As a result, in the pneumatic tire having a block group consisting of a plurality of blocks each having a polygonal bottom surface on the tread surface of the tire, the block group By setting the block density per unit actual contact area to a specific appropriate range, the total edge length and edge direction of each block are increased, and an excellent edge effect is exhibited. Each contact is improved and high driving performance is exhibited. Moreover, by reducing the size of each block, the distance from the central area of the block to the periphery of the block is reduced. The knowledge that the removal effect of a film | membrane improves was acquired.

  Furthermore, the inventors have increased the rigidity of the block against the input from the road surface by inserting a sheet made of organic fibers into the tread rubber of the tread portion in a range of 50% or more of the unit actual ground contact area. As a result of suppressing the bending deformation of the block and increasing the contribution of the shear deformation to obtain a larger cornering force, it has been found that the steering stability can be further improved.

In a pneumatic tire having a block group consisting of a plurality of blocks having a polygonal surface shape on the tread portion of the tire,
In the reference area of the block group, the reference pitch length of the block in the block group is defined as P (mm), the width of the block group is defined as W (mm), and the reference pitch length P and the width W are defined. The number of blocks present in the a (piece), the negative rate in the reference area is N (%),
The block number density S per unit actual contact area of the block group given by a / (P × W × (1-N / 100)) is within the range of 0.003 / mm ^{2 to} 0.04 / mm ² ,
Furthermore, a sheet made of organic fibers is embedded in the tread rubber of the tread portion in a range of 50% or more of the actual ground contact area of the block group.

  The “reference pitch length of the block” here refers to the minimum unit of the repeated pattern of the block in one block row constituting the block group. For example, the pattern is defined by one block and a groove defining the block. If a repeating pattern is specified, the block's reference pitch length is the sum of the tread circumferential length of one block and the tread circumferential length of one groove adjacent to this block in the tread circumferential direction. Say it. The “width W of the block group” refers to the length in the tread width direction of the block group formed by densely arranging the blocks. For example, when the block group exists in the entire tread, it refers to the tread ground contact width. Moreover, when it is divided by the thick groove | channel which is continuous in the circumferential direction, it is set as the width within the divided range. The “actual ground contact area” of the block group shall mean the total surface area of all blocks in the reference area of the block group, in other words, defined by the product of the reference pitch length P and the width W. This refers to the area obtained by subtracting the area of the groove defining each block from the area of the reference area. The “block” here is a column having a polygonal bottom surface.

  In the pneumatic tire of the above invention, it is preferable to arrange the blocks in a staggered pattern in the tread circumferential direction.

  In the pneumatic tire according to the present invention, a configuration in which the blocks are densely arranged while securing a sufficient groove area in the block group is adopted, so that the total edge length and edge direction of each block are increased. , An excellent edge effect can be exhibited. Moreover, the grounding property of each block is improved, and high running performance can be exhibited. In addition, by reducing the size of each block, the distance from the central area of the block to the periphery of the block is reduced, and the water film removal effect by the block is improved. In addition, a sheet made of organic fibers is embedded in the tread rubber of the tread portion of the tire in a range of 50% or more of the actual ground contact area of the block group, so that the block of the block against input from the road surface. It is possible to increase rigidity, suppress bending deformation of the block, increase the contribution of shear deformation, and obtain a larger cornering force.

  Therefore, according to the pneumatic tire of the present invention, it is possible to dramatically improve the wet performance by ensuring excellent grounding property and edge effect and efficiently removing the water film by the block. Furthermore, since the cornering force is increased, very high steering stability can be realized.

It is the partial expanded view showing the tread pattern of the pneumatic tire of one embodiment concerning the present invention. It is the figure which represented typically the block arrangement of the tread part concerning one Embodiment of this invention. It is sectional drawing of the tread part of the pneumatic tire concerning 1st embodiment of this invention. It is sectional drawing of the tread part of the pneumatic tire concerning 2nd embodiment of this invention. It is sectional drawing of the tread part of the pneumatic tire concerning 3rd embodiment of this invention. It is sectional drawing of the tread part of the pneumatic tire of the comparative example with respect to this invention. (a) is a figure shown with a three-dimensional coordinate axis | shaft about the case where the insertion angle of an organic fiber sheet is the most suitable. (b) is a figure which shows the angle with respect to the tire equatorial plane of an organic fiber sheet with a three-dimensional coordinate axis. (c) is a figure which shows the angle with respect to the tire equatorial plane of an organic fiber sheet with a two-dimensional coordinate axis. It is the figure which represented typically the tread pattern of the pneumatic tire concerning a prior art example.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial development view showing a tread pattern of a pneumatic tire (hereinafter referred to as “tire”) according to an embodiment of the present invention. In FIG. 1, the direction orthogonal to the equator plane C of the tire indicates the tread width direction.

Although the tire of this embodiment is not illustrated, a carcass extending in a toroidal shape between a pair of left and right bead cores, a belt disposed on the outer side in the tire radial direction of the crown portion of the carcass, and an outer side in the tire radial direction of the belt It has a tire structure according to a customary manner including a tread portion arranged, and has a tread pattern shown in FIG. 1 in the tread portion.

As shown in FIG. 1, the tire has a block group GB in which a plurality of independent blocks 3 partitioned by a groove 2 are densely packed in a tread portion 1. The block group GB exists in the entire tread portion 1. Here, the surface contour shape of each block 3 is an octagon, and each block 3 is arranged in a staggered pattern in the tread circumferential direction. The tire has a reference pitch length P (mm) in the tire circumferential direction of the block 3 in the block group GB, and a width W (mm) of the block group GB (in this embodiment, the entire tread portion 1 is blocked). 3 is equal to the tread grounding width TW.), The reference zone Z of the block group GB (the area shown by hatching in FIG. 1) divided by the reference pitch length P and the width W When the number of blocks 3 existing in is a (pieces), and the negative rate in the reference zone Z is N (%),
S = a / (P × W × (1-N / 100))
The block number density S (piece / mm ² ) per unit actual ground contact area of the block group is in the range of 0.003 piece / mm ^{2 to} 0.04 piece / mm ² . When counting the number a of blocks 3 in the reference zone Z of the block group, when the block 3 exists across the reference zone Z and cannot be counted as one, with respect to the surface area of the block 3, It is counted using the ratio of the remaining area of the block 3 remaining in the reference area. For example, in the case of a block straddling the inside and outside of the reference area Z and having only half of it in the reference area Z, such as a block indicated by reference numeral B1 in FIG. 1, it can be counted as 1/2.

  In the tire of this embodiment, since the configuration in which the blocks 3 are densely arranged while ensuring a sufficient groove area in the block group GB is adopted, the total edge length and edge direction of each block 3 (different) The number of edges oriented in the direction) can be increased, and an excellent edge effect can be exhibited. In addition, since the size of the block 3 is reduced and the sipe is not formed, the grounding property of each block can be improved and high performance on ice can be exhibited. In addition, by reducing the size of each block 3, the distance from the central area of the block 3 to the peripheral edge of the block can be reduced, so that the water film removal effect by the block 3 can be improved.

Therefore, according to the tire of this embodiment, it is possible to dramatically improve the performance on ice by ensuring excellent grounding performance and edge effect and efficiently removing the water film by the block 3. . In addition, if the number density S of the blocks 3 in the block group GB is in the range of 0.0035 to 0.03 / mm ² , both the block rigidity and the edge effect can be achieved at a higher level, which is more effective. In addition, the wet performance can be improved.

  Further, according to the tire of this embodiment, since each block 3 is arranged in a staggered pattern in the tread circumferential direction, each edge is caused to act sequentially while forming more blocks 3 during tire rolling. A more excellent edge effect can be exhibited. In addition, since the ground contact timing to the road surface can be shifted between the blocks 3 adjacent in the tread width direction, pattern noise can also be reduced.

In the present invention, the negative rate N in the block group GB is preferably 5% to 50%. When the negative rate N in the block group GB is less than 5%, the groove area is too small and the drainage becomes insufficient, and the size of each block becomes too large, making it difficult to achieve the required edge effect. On the other hand, if it exceeds 50%, the ground contact area becomes too small and the steering stability may be lowered. In addition, when the number density S of the blocks 3 in the block group GB is less than 0.003 (pieces / mm ² ), it is difficult to realize a high edge effect without forming a sipe, while the number density S of the blocks 3 is 0.04. If it exceeds (pieces / mm ² ), the block 3 becomes too small and it is difficult to achieve the required block rigidity.

  Furthermore, in the present invention, it is important that a sheet made of organic fibers is embedded in the tread rubber of the tread portion in a range of 50% or more of the actual ground contact area of the block group.

Here, FIG. 2 schematically shows the block arrangement of the tread portion of the tire according to the present invention. 3 to 6 are views showing a state in which a sheet made of organic fibers is embedded in the tread rubber of the tread portion of the tire.
Hereinafter, with reference to these drawings, a mode of embedding organic fibers will be described in detail.

  FIG. 3 shows the tire according to the first embodiment relating to the block shape of the present invention, when the block arrangement of the tread portion of the tire is represented as shown in FIG. 2, when cut along the line AA ′. A sectional view is shown. Looking at the characteristics of the tire in a sectional view in FIG. 3, in FIG. 3, the organic fibers are embedded in the tread rubber.

  Here, the embedded organic fiber sheet needs to partially retain tension. The material may be glass fiber, carbon fiber, non-woven fabric, etc., for example.

Since the sheet made of organic fibers is embedded in the tire tread rubber in this way, the rigidity against the input from the road surface, particularly when the vehicle turns, is increased, bending deformation is suppressed and shear deformation is suppressed. To be migrated.
Therefore, the tire can obtain a larger cornering force due to the restoring force against the shear deformation, and as a result, the steering stability during cornering is dramatically improved.

The total area of the embedded organic fiber sheet is preferably 50% or more of the actual ground contact area of the block group. This is because if it is less than 50%, sufficient rigidity for the input from the road surface cannot be obtained. The same applies to the following second and third embodiments.
Further, in FIG. 3, one organic fiber sheet is embedded with an area of 50% or more of the actual ground contact area of the block group. The organic fiber sheet may be cut and embedded.

  FIG. 4 is a cross-sectional view of the tire according to the second embodiment relating to the block shape of the present invention, taken along the line AA ′ when the block arrangement of the tread portion of the tire is represented as shown in FIG. Represents. When the characteristics of the tire are seen in a cross-sectional view in FIG. 4, compared to the comparative example of FIG. 6 and the first embodiment of FIG. 3, a sheet made of organic fibers is present inside the block rubber of the tread portion. It is characterized by being buried. Preferably, the organic fiber sheet is embedded in a range of 50% or more of the actual ground contact area of the block group.

  In this case, as the block is bent, the organic fibers are partially stretched, receive tension, and increase in rigidity. Therefore, bending deformation of the block in which the sheet made of organic fibers is embedded is suppressed. Therefore, since bending deformation is suppressed and shear deformation easily occurs, the tire can obtain a larger cornering force by the restoring force against the shear deformation, and as a result, steering stability during cornering is dramatically improved. Will be improved.

  FIG. 5 is a cross-sectional view of the tire according to the third embodiment of the present invention, cut along the A-A ′ line when the block arrangement of the tread portion of the tire is represented as shown in FIG. 2. When looking at the characteristics of the tire in a cross-sectional view in FIG. 5, compared with the comparative example of FIG. 6 and the first and second embodiments of FIG. 3, FIG. 4, the inside of the tread rubber of the tread portion, And the sheet | seat which consists of organic fiber is embed | buried under the tire radial direction inner side from the said block. Preferably, the organic fiber sheet is embedded in a range of 50% or more of the actual ground contact area of the block group.

  A block in which a sheet made of organic fibers is embedded is suppressed in bending deformation, bending deformation is suppressed, and shear deformation is likely to occur. Therefore, the tire can obtain a larger cornering force due to the restoring force against the shear deformation. As a result, the steering stability during cornering is dramatically improved.

  In the first to third embodiments, the same principle can be applied to small curves that occur when the vehicle moves straight to the left or right when moving straight ahead or when the vehicle moves left or right during a lane change. It has a beneficial effect on prevention and handling stability.

Further, regarding the third embodiment, as shown in FIG. 7 (a), the tire width direction is the x axis (the vehicle inner side 7 when the tire is mounted is the positive direction), and the tire circumferential direction 12 is the y axis (vehicle The traveling direction during straight travel is defined as the positive direction), and the z-axis (the belt side is defined as the positive direction with respect to the road surface side) perpendicular to the x-axis and the y-axis.
At this time, in order to maximize the effect of suppressing bending deformation, the sheet made of organic fibers is in a plane parallel to the xy plane at the position inside the tread rubber of the tread portion and on the inner side in the tire radial direction from the block. It is preferable that it is buried along.
On the other hand, as shown in FIGS. 7 (b) and 7 (c), when the sheet made of organic fibers is embedded along a plane parallel to a plane obtained by rotating the xy plane around the y axis, The angle of the clockwise rotation from the positive direction of the z-axis in the xz plane (this is referred to as “the angle with respect to the equator plane of the tire”) is allowed from 70 ° to 110 °, and the effect of the present invention Is effective.

  Moreover, it is preferable that the polygonal block in this invention is a polygonal block which consists of the number of angles more than a pentagon. This is because, in the case of a pentagon or more, the edge effect increases because the edge direction increases and the total edge length also increases.

  Next, in order to confirm that there is a difference in steering stability between the conventional tire and the tire of the present invention, a test run by a driver was performed. The vehicle used was a front-wheel drive sedan type vehicle. Here, as Example 1, a pneumatic tire having a tread portion of the type shown in FIG. 4, and as Examples 2, 3, and 4, a pneumatic tire having a tread portion of the type shown in FIG. As a conventional example, a pneumatic tire having a tread portion of the type shown in FIG. 8 was prepared.

  Table 1 shows the specifications of the tires of Example 1, Example 2, Example 3, Example 4, and Comparative Example. As shown in Table 1, Example 1, Example 2, Example 3, Example 4 and Comparative Example are different only in the presence or absence of the embedding of the sheet made of organic fibers and the manner of embedding. The specs are common.

  In this test, cornering was carried out from the straight-line stability to see the handling stability. Table 2 shows a result of comparison of steering stability when the tires of the conventional example, Example 1, Example 2, Example 3, Example 4, and Comparative Example are attached, with a maximum of 10 points.

  As shown in Table 2, the test results of Example 1, Example 2, Example 3 and Example 4 using the pneumatic tire according to the present invention are items of a steering stability test on a dry road surface. In all of the straight running stability, lane change, cornering, and marginal driving, the results are equivalent to or better than those of the conventional example and the comparative example. Overall, the pneumatic tire according to the present invention improves the driving stability on the dry road surface. It can be said that it is excellent. In addition, the pneumatic tires according to Example 1, Example 2, Example 3, and Example 4 in the response, grip, and controllability, which are items of the handling stability test on the wet road surface, are the conventional examples. As a result, it can be said that the pneumatic tire according to the present invention is excellent in driving stability on a wet road surface. Thus, according to the present invention, a pneumatic tire is provided in which the handling stability on dry and wet road surfaces is greatly improved.

  Further, referring to Table 2, when comparing Examples 2, 3, and 4, the organic fiber sheet was embedded within a range of 70 degrees to 110 degrees with respect to the equator plane of the tire. The tire according to Example 3 is an item of the steering stability test on the dry road surface, the straight-running stability, the lane, than the tire according to Example 4 in which the organic fiber sheet is embedded at an angle outside the range. Excellent results have been obtained in all changes, cornering, and marginal driving, and excellent results have been obtained in response, grip, and control, which are items for handling stability tests on wet surfaces. Overall, it can be said that the handling stability is high.

  Tires with improved cornering performance can be manufactured and marketed.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Groove 3 Block 4 Tire circumferential direction 5 Tire width direction 6 Vehicle outer side at the time of vehicle mounting 7 Vehicle inner side at the time of vehicle mounting
8 Belt side
9 Road surface
9a Road side
10 Input from the road surface
11 Sheet made of organic fibers
12 Tire circumferential direction
C Equatorial plane
GB block group P Reference pitch length of block group
W Block width
Z Reference zone α, β, γ Angle to tire equatorial plane

Claims (5)

In a pneumatic tire having a block group consisting of a plurality of blocks having a polygonal surface shape on the tread portion of the tire,
In the reference area of the block group, the reference pitch length of the block in the block group is defined as P (mm), the width of the block group is defined as W (mm), and the reference pitch length P and the width W are defined. The number of blocks present in the a (piece), the negative rate in the reference area is N (%),
The block number density S per unit actual contact area of the block group given by a / (P × W × (1-N / 100)) is within the range of 0.003 / mm ^{2 to} 0.04 / mm ² ,
Further, a pneumatic tire is characterized in that a sheet made of organic fibers is embedded in the tread rubber of the tread portion in a range of 50% or more of the unit actual ground contact area.   2. The pneumatic tire according to claim 1, wherein the position where the organic fiber sheet is embedded is inside the block rubber.   2. The pneumatic tire according to claim 1, wherein a position where the sheet made of the organic fiber is embedded is inside in the tire radial direction from the block.   4. The pneumatic tire according to claim 3, wherein the sheet made of an organic fiber has an angle with respect to an equatorial plane of the tire in a range of 70 degrees to 110 degrees.   5. The pneumatic tire according to any one of claims 1 to 4, wherein the polygonal block is a polygonal block having a number of pentagons or more.

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