JP2011073475A - Tire for winter use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire for winter use capable of making up for insufficiency of turning running performance on an ice road surface when the tire is brand-new. <P>SOLUTION: In this tire for winter use, a plurality of shallow grooves 6 setting depth and width of the groove to 0.1-0.8 mm, respectively, are formed to extend in the direction of radiation from a central part of a block 4 toward an edge part and open at an edge end of the block 4 on a surface 4 of the block in addition to a sipe 5 extended in the direction of tire width. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a winter tire, and more particularly to a winter tire that improves the turning performance on an icy road surface when new.

  In general, studless tires designed to improve driving performance on icy road surfaces have a tread surface formed into a block pattern and a large number of sipes extending in the tire width direction on the block surface. And the driving performance on the frozen road surface is secured by utilizing the water film removal effect.

  However, the tread surface of a tire when it is new is finished with a mirror-like surface by a vulcanization mold, and at the same time, the release agent applied to the mold penetrates and the surface is formed smoothly. Because the frictional force on the frozen road surface is insufficient and the performance on ice cannot be obtained at the initial stage of running when the tire is new, so that the original tread rubber is exposed due to the abrasion of the skin and the desired performance on ice is exhibited. Until then, there is a problem that you have to be accustomed.

  As a countermeasure, in order to compensate for the performance degradation at the beginning of running, a shallow groove with a groove depth shallower than the sipe and a groove width of about 0.1 to 0.8 mm is formed on the surface of the block. It has been practiced to form a large number of parallel lines and supplement the performance on ice at the beginning of running by the edge effect of these shallow grooves (see, for example, Patent Document 1).

  However, this type of tire has a problem that it is difficult to ensure on-ice performance at the initial stage of running depending on the extending direction of the shallow groove formed on the surface of the block. There was a problem that it could not be obtained.

JP 2004-34903 A

  An object of the present invention is to solve the above-described conventional problems, and to provide a winter tire that can sufficiently compensate for the lack of turning performance on an icy road surface when it is new.

  In order to solve the above-mentioned object, the winter tire of the present invention forms a plurality of blocks on the tread surface, forms a plurality of sipes extending in the tire width direction on the surface of these blocks, and in addition to the sipes. In the winter tire in which a plurality of shallow grooves each having a groove depth and a groove width of 0.1 to 0.8 mm are formed, the shallow grooves are extended in the radial direction from the center of the block toward the edge. And an opening at the edge of the block.

Furthermore, in the structure mentioned above, it is preferable to comprise as described in the following (1)-(7).
(1) The shallow groove is formed in a curve or a straight line in plan view. Here, when the shallow groove is formed into a curve, the curve is formed into an arcuate curved curve, and the radius of curvature of the curved curve is gradually increased from the center of the block toward the edge of the block. It should be larger. Further, when the shallow groove is formed in a straight line, the straight line may be formed in a refraction line that bends in the same direction, and the refraction angle of the refraction line with respect to the refraction direction may be 120 ° or more and less than 180 °.
(2) The end of the shallow groove at the center of the block is disposed at a position corresponding to within 20% of the linear distance from the center of gravity of the block to the edge of the block. In this case, at least three shallow groove ends of the shallow grooves may be connected at the center of gravity of the block.
(3) The entrance angle of the shallow groove at the edge position of the block is set to 30 to 150 °.
(4) The shallow grooves are composed of two or more types having different lengths, and the shallow grooves having different lengths are alternately arranged adjacent to each other.
(5) The depth of the shallow groove is gradually increased from the center of the block toward the edge of the block.
(6) The groove width of the shallow groove is gradually increased from the center of the block toward the edge of the block.
(7) The sum of the cross-sectional areas of the shallow grooves at a position where the linear distance from the center of gravity of the block is the same is made equal to the sum of the cross-sectional areas of the shallow grooves at positions where the linear distances are different.

  According to the above-described present invention, in addition to the sipe extending in the tire width direction on the surface of the block, a plurality of shallow grooves each having a groove depth and a groove width of 0.1 to 0.8 mm are provided at the center of the block. Since it was formed so as to extend radially from the edge toward the edge and open at the edge of the block, even when a new tire was turned, the shallow groove extending radially The frictional force with the frozen road surface can be secured by the edge effect, and at the same time, the efficiency of the water film interposed between the frozen road surface and the outside from the center of the block along the shallow groove extending radially is effective. Since it can be discharged well, it is possible to efficiently improve the turning performance on the road surface on ice when it is new.

It is a partial top view which expands and shows an example of the tread surface of the winter tire by embodiment of this invention. It is an enlarged plan view which takes out and shows a block from the tread surface of FIG. FIG. 6 is a plan view showing a sipe removed from a block corresponding to FIG. 2 according to another embodiment of the present invention. (A) is a top view corresponding to FIG. 3 by further another embodiment of this invention, (b) is a top view for demonstrating the planar form of the shallow groove | channel in (a). FIG. 6 is a plan view corresponding to FIG. 3 according to still another embodiment of the present invention. It is sectional drawing which shows the cross-sectional shape of the shallow groove | channel by embodiment of this invention. It is a top view equivalent to FIG. 2 which shows the surface form of the block in the conventional tire employ | adopted in the Example.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a partial plan view showing an example of a tread surface of a winter tire according to an embodiment of the present invention, and FIG. 2 is an enlarged plan view showing a block taken out from the tread surface of FIG.

  In FIG. 1, a tread surface 1 is formed with a plurality of blocks 4 defined by a plurality of main grooves 2 extending in the tire circumferential direction and a plurality of lateral grooves 3 extending in the tire width direction. A plurality of sipes 5 extending in the tire width direction are formed. Further, in the present invention, as shown in FIG. 2, in addition to the sipes 5, a plurality of shallow grooves 6 having a groove depth and a groove width of 0.1 to 0.8 mm are formed from the center of the block 4 to the edge. It extends in the radial direction toward the part and is formed so as to open at the edge of the block 4.

  With this configuration, even when a new tire is turned, the frictional force with the frozen road surface can be ensured by the edge effect of the shallow groove 6 extending in the radial direction. Since the water film interposed between the frozen road surface and the shallow groove 6 extending in the radial direction can be discharged efficiently from the center of the block 4 to the outside, The turning performance can be improved efficiently.

  In the present invention, it is preferable that the shallow groove 6 described above is configured by a curve or a straight line (a curve in FIG. 2) in plan view. When the shallow groove 6 is configured by a curve, the curve is configured by an arc-shaped curved curve, and the curvature radius of the curved curve is gradually increased from the center of the block 4 toward the edge of the block 4. It is good to form. Thereby, the water film interposed between the block 4 and the frozen road surface can be efficiently discharged outward.

  Further, when the shallow groove 6 is constituted by a straight line, the straight line is formed in a straight shape as shown in FIG. 3 and is also constituted by a refracting straight line that bends in the same direction as illustrated in FIG. The refraction angle β (see FIG. 4B) with respect to the refraction direction of the refraction line is preferably 120 ° or more and less than 180 °. Thereby, the water film interposed between the block 4 and the frozen road surface can be efficiently discharged toward the outside along the shallow groove 6 while ensuring the frictional force with the frozen road surface.

  In the winter tire of the present invention, the straight distance W from the center of gravity P of the block 4 to the edge of the block 4 from the end 6a of the shallow groove 6 in the center of the block 4 from the viewpoint of ensuring drainage of the water film on the frozen road surface. It is good to arrange | position in the position corresponded within 20% of (refer FIG. 3). More preferably, as illustrated in FIG. 5, the terminals 6 a of at least three (three in the figure) shallow grooves 6 among the plurality of shallow grooves 6 may be connected at the position of the center of gravity P of the block 4. Thereby, the water film interposed between the block 4 and the frozen road surface can be discharged more efficiently toward the outside.

  In the present invention, the penetration angle α of the shallow groove 6 at the edge position of the block 4 is more preferably set to 30 to 150 °, most preferably 45 to 120 °. Thereby, the water film interposed between the block 4 and the frozen road surface can be discharged more efficiently toward the outside.

  In the winter tire of the present invention, the number of shallow grooves 6 formed on the surface of each block 4 is not particularly limited, but from the viewpoint of ensuring the drainage of the water film on the frozen road surface, adjacent shallow grooves 6 are formed. The number of shallow grooves 6 may be set so that the angle formed between the grooves 6 and 6 is 45 ° or less, preferably 5 to 30 °. More preferably, the shallow grooves 6 may be formed of two or more types having different lengths, and the shallow grooves 6 having different lengths may be alternately or randomly adjacently disposed.

  In the present invention, more preferably, the depth of the shallow groove 6 is gradually increased from the center of the block 4 toward the edge of the block 4. Thereby, the drainage effect of a water film can be improved further. Furthermore, the groove width of the shallow groove 6 can be gradually increased from the center of the block 4 toward the edge of the block 4.

  In the winter tire of the present invention, as shown in FIG. 6, the boundary between the groove wall and the groove bottom of the shallow groove 6 is preferably formed on a curved surface having a radius R. Here, the size of the radius R is not particularly limited, but may be set to about 0.1 to 0.5 mm. Thereby, the drainage performance can be secured satisfactorily.

  In the winter tire of the present invention, more preferably, the sum of the cross-sectional areas of the shallow grooves 4 at positions where the linear distance from the center of gravity P of the block 4 is the same, and the sum of the cross-sectional areas of the shallow grooves 4 at positions where the linear distances are different. It is good to adjust so that it becomes equivalent. Thereby, a better drainage performance can be ensured regardless of the turning angle during turning.

  In the present invention, the groove depth and groove width of the shallow groove 4 formed on the tread surface 1 are 0.1 to 0.8 mm, respectively, because the groove depth and groove width of the shallow groove 4 are 0.1 mm. If the ratio is less than 0.8 mm, the draining effect of the water film interposed between the block 4 and the frozen road surface will be insufficient. If the thickness exceeds 0.8 mm, the draining effect of the water film is good. This is because the braking / driving performance on the frozen road surface is deteriorated because the contact area with is too small. Here, when the shallow groove 4 does not have a clear edge in the opening, the groove width of the shallow groove 4 described above is the intersection of the extension line of both side walls of the shallow groove 4 and the extension line of the tread surface 1. Measured by the distance between.

  As described above, the winter tire of the present invention includes a plurality of shallow grooves each having a groove depth and a groove width of 0.1 to 0.8 mm in addition to the sipe extending in the tire width direction on the surface of the block. Even if a new tire is turned, it can be turned excellently by extending in the radial direction from the center to the edge of the block and opening at the edge of the block. It is designed to demonstrate its performance, and has an excellent effect while having a simple configuration. Therefore, it can be widely applied to studless tires in which a large number of sipes extending in the tire width direction are formed on the tread surface. .

<Conventional example, Examples 1-5>
The basic structure of the tire size 225 / 65R17 102Q, the tread pattern is as shown in FIG. 1, and the arrangement of shallow grooves formed on the surface of each block is as shown in FIG. 7 and the conventional tire (conventional example) as shown in FIG. The tires of the present invention (Examples 1 to 5) in which the average intrusion angle α of the shallow groove at the terminal position of the block, the groove depth of the shallow groove, and the groove width of the shallow groove are different as shown in Table 1, respectively. Each was produced. In Example 5, the radius of curvature of the shallow groove was gradually increased from the center of the block toward the edge.

  For these six types of tires, the turning performance was evaluated by the following test method, and the results are also shown in Table 1 using an index with the conventional example being 100. The larger the value, the better the turning performance.

[Evaluation of turning performance]
Each tire is fitted to a rim (size: 17 × 7J), filled with air pressure of 220 kPa, mounted on the front and rear wheels of the vehicle (RAV4), and the maximum speed at which grip driving can be performed on an ice turning test road with a radius of 50 m The vehicle was turned for 5 laps, the running time for each lap was measured, and the turning performance was evaluated using the running time for 3 laps excluding the maximum and minimum values.

  From the results in Table 1, it can be seen that the turning performance of the tire of the present invention is improved as compared with the conventional tire.

<Examples 6 to 8>
Tire size 225 / 65R17 102Q, the basic configuration of the tread pattern is as shown in FIG. 1, the arrangement of shallow grooves formed on the surface of each block is as shown in FIG. 2, and the average penetration angle α of the shallow grooves at the end positions of the blocks The tires of the present invention (Examples 6 to 8) in which the depth and width of the shallow groove were changed as shown in Table 1 from the center to the edge of the block were prepared. . In addition, when the groove depth and groove width of the shallow groove were changed at the center portion and the edge portion of the block, this change was gradually performed.

  With respect to these three types of tires, the turning performance was evaluated by the same test method as described above, and the results are also shown in Table 2 using an index with the above-mentioned conventional example being 100. The larger the value, the better the turning performance.

  From the results in Table 2, it can be seen that the tire of the present invention has improved turning performance as compared with the conventional tire.

1 tread surface 4 block 5 sipe 6 shallow groove 6a shallow groove end α shallow groove penetration angle β bending angle P block center of gravity W block center of gravity to edge

Claims (11)

A plurality of blocks are formed on the tread surface, and a plurality of sipes extending in the tire width direction are formed on the surfaces of the blocks, and in addition to the sipes, the groove depth and the groove width are set to 0.1 to 0.3 mm, respectively. In winter tires with multiple shallow grooves of 8mm,
A winter tire in which the shallow groove is formed so as to extend in a radial direction from a center portion of the block toward an edge portion and to open at an edge portion of the block.   The winter tire according to claim 1, wherein the shallow groove is a curve or a straight line in a plan view.   The winter tire according to claim 2, wherein the curved line is an arc-shaped curved curve, and the radius of curvature of the curved curve is gradually increased from the center of the block toward the edge of the block.   The winter tire according to claim 2, wherein the straight line is composed of a refraction line that bends in the same direction, and a refraction angle of the refraction line with respect to the refraction direction is 120 ° or more and less than 180 °.   The terminal of the said shallow groove in the center part of the said block is arrange | positioned in the position corresponded within 20% of the linear distance from the gravity center of the said block to the edge of this block. Winter tire.   The winter tire according to claim 5, wherein at least three shallow groove ends of the shallow grooves are connected to each other at a center of gravity of the block.   The winter tire according to any one of claims 1 to 6, wherein an entrance angle of the shallow groove at an edge position of the block is 30 to 150 °.   The winter tire according to any one of claims 1 to 7, wherein the shallow grooves have two or more types, and the shallow grooves having different lengths are alternately disposed adjacent to each other.   The winter tire according to any one of claims 1 to 8, wherein a depth of the shallow groove is gradually increased from a center portion of the block toward an edge of the block.   The winter tire according to any one of claims 1 to 9, wherein a groove width of the shallow groove is gradually increased from a center portion of the block toward an edge of the block.   The sum of the cross sectional areas of the shallow grooves at a position where the linear distance from the center of gravity of the block is the same is equal to the sum of the cross sectional areas of the shallow grooves at a position where the linear distance is different. The winter tire according to any one of the above.