JP4628055B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having a tread having a large number of blocks formed by a plurality of main grooves intersecting each other.

  Conventionally, a tire having a plurality of grooves in the tire circumferential direction and the tire width direction and forming a plurality of blocks in the tread by intersecting the plurality of grooves improves the drainage performance on ice and snow. A plurality of sipes are formed in each block.

In recent years, pneumatic radial tires in which wavy sipes having different amplitudes are formed according to the position of the block in the tire width are known (for example, Patent Document 1). In this tire, since the sipes are formed in a wave shape, the rigidity of the block is improved as compared with the conventional tire, so that the braking / driving performance and cornering performance on ice and snow are also improved.
Japanese Patent Laid-Open No. 11-310013

  However, the sipe formed on the pneumatic radial tire described above is wavy in the width direction from the block surface to the inside, but is straight in the depth direction. Because of the inclination, the rigidity of the block, such as the tendency for wear to proceed, was insufficient. Therefore, it has been desired to improve the shape of the sipe formed on the block, improve the rigidity of the block, and further improve the braking / driving performance and cornering performance on ice and snow.

  Then, this invention makes it a subject to provide the pneumatic tire which can improve the braking / driving performance and cornering performance on ice and snow in view of said problem.

In order to solve the above problems, the present invention is characterized in that a tread is provided with a number of blocks formed by a plurality of main grooves intersecting each other, and the block has at least one sipe having a wavy shape in the tire width direction. a pneumatic tire but which is formed, sipes, Oite in the depth direction is a tire radial direction, is curved in the tire circumferential direction, the curved is the boundary tire equator line, an inner when the vehicle mounted The gist is that it is the opposite of the outside.

According to the pneumatic tire according to the feature of the present invention, the sipe is curved in the tire circumferential direction in the depth direction , and the curvature is opposite between the inner side and the outer side when the vehicle is mounted, with the tire equator line as a boundary. Therefore, the rigidity of the block can be improved. Accordingly, the end of the block is less likely to be inclined, and the end of the block effectively scratches the road surface, so that the braking / driving performance and cornering performance on ice and snow can be further improved.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can improve the braking / driving performance and cornering performance on ice and snow can be provided.

  Below, the structure of the tire which concerns on this embodiment is demonstrated.

  FIG. 1 is a view showing a tread pattern 10 of a tire in the present embodiment.

  The tread pattern 10 includes a circumferential groove 1, a transverse cross-sectional groove 2, and a block 3, and is formed on a tread that is a thick rubber layer that comes into contact with the tread surface.

  The circumferential groove 1 is a groove formed in the tire circumferential direction S in the tread.

  The cross-sectional groove 2 is a groove formed in the tire width direction W in the tread.

  The block 3 is a portion formed by intersecting the circumferential groove 1 and the transverse groove 2 with each other and protruding from the circumferential groove 1 or the transverse groove 2.

  In FIG. 1, two circumferential grooves 1 are provided, and accordingly, three blocks 3 are provided in the tire width direction W. This represents a part of the tread pattern for convenience of explanation. Of course, the numbers of the circumferential grooves 1, the cross-sectional grooves 2, and the blocks 3 are not limited thereto. Further, a block 3 formed on the inner side (hereinafter referred to as the IN side) when the vehicle is mounted with the center line (hereinafter abbreviated as CL) being the center in the tire width direction W as a boundary is referred to as a block 3R. The block 3 formed above is referred to as a block 3C, the block 3 formed on the outside (hereinafter referred to as OUT side) when the vehicle is mounted is referred to as a block 3L, and matters common to all the blocks 3R, 3C, and 3L are as follows. This will be described as block 3.

  Further, five sipes 4 formed in a wave shape in the tire width direction W are formed in the block 3 in parallel in one block. In this embodiment, the sipe 4 formed in the block 3R is the sipe 4R, the sipe 4 formed in the block 3C is the sipe 4C, and the sipe 4 formed in the block 3L is the sipe 4L. Items common to all of 4R, 4C, and 4L will be described as Sipe 4.

  FIG. 2 is an enlarged perspective view of the block 3 in the present embodiment.

  As shown in the figure, the sipe 4 formed on the block 3 is curved in the depth direction of the block 3 and the A direction or B direction which is the tire circumferential direction, respectively. Specifically, the sipe 4L formed in the block 3L is curved in the depth direction and the A direction, and the sipe 4R formed in the block 3R is curved in the depth direction and the B direction. The sipe 4C formed on the OUT side from the CL is curved in the depth direction and the A direction, and the sipe 4C formed on the IN side from the CL is curved in the depth direction and the B direction. . That is, the sipe 4 formed on the IN side from the CL is all curved in the depth direction and the B direction, and the sipe 4 formed on the OUT side from the CL is all curved in the depth direction and the A direction.

  In the figure, for simplification of the drawing, only the foremost sipe 4 among the five sipes 4 formed in one block 3 is curved. The sipes 4 are all formed in the same manner.

(Operation and effect of the pneumatic tire according to the present embodiment)
According to the pneumatic tire according to the present embodiment, the sipe 4 formed in the block 3 is curved in the depth direction and the tire circumferential direction, and the curve is opposite on the IN side and the OUT side with the tire equator line as a boundary. Therefore, the rigidity of the block 3 can be improved. As a result, the end of the block 3 is less likely to be inclined, and the end of the block 3 effectively scratches the road surface, so that the braking / driving performance and cornering performance on ice and snow can be further improved.

  When the shape of the sipe 4 formed in the block 3 is the same, the longer the total length of the sipe 4 formed in one block 3, the better the braking / driving performance and cornering performance on ice and snow. be able to.

  Note that the sipe 4 formed on the OUT side is curved in the depth direction and the A direction, and the sipe 4 formed on the IN side is curved in the depth direction and the B direction. It is not limited to this, and the reverse may be possible.

  Examples of the pneumatic tire according to the embodiment of the present invention will be described in detail below.

  As shown in Table 1, tires of Example 1 and Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 4 and Conventional Example 1 were manufactured, and performance on snow, performance on ice, DRY performance and WET The performance was examined.

  In addition, Example 1 is a tire in which a sipe 4 similar to that shown in FIG. 2 of the present embodiment is formed. In Example 2, as shown in FIG. As shown in FIG. 3B, the sipe 4 on the OUT side from the CL is curved in the depth direction and the A direction, and the sipe 4 on the IN side from the CL is curved in the depth direction and the B direction. It had been.

  In Comparative Example 1, as shown in FIG. 4A, six sipes 4 are formed in one block 3, and as shown in FIG. 4B, all the sipes 4 are in the depth direction. And curved in the A direction.

  In Comparative Example 2, as shown in FIG. 5A, five sipes 4 are formed in one block 3, and as shown in FIG. It was curved in the direction.

  In Comparative Example 3, six sipes 4 are formed in one block 3 as shown in FIG. 6A, and all the sipes 4 are not curved as shown in FIG. 6B. It was carved toward the inside of the block 3 perpendicular to the surface of the block 3.

  In Comparative Example 4, as shown in FIG. 7A, four sipes 4 are formed in one block 3, and as shown in FIG. 7B, all the sipes 4 are not curved. It was carved toward the inside of the block 3 perpendicular to the surface of the block 3.

  In Conventional Example 1, as shown in FIG. 8A, five sipes 4 are formed in one block 3, and as shown in FIG. 8B, all the sipes 4 are not curved. It was carved toward the inside of the block 3 perpendicular to the surface of the block 3.

  The mounted rim was 6.5 J, and the filling internal pressure was 230 kPa. Furthermore, the vehicle used for the test was an FF passenger vehicle with ABS, and the tires were mounted on all four wheels of the vehicle. The load applied to the tire corresponds to a case where the front wheels are 4.82 kN and the rear wheels are 90 kN, and two people get on. Further, in Table 1, the sipe total length index indicates the length of the sipe 4 when the sipe 4 formed in a wave shape is extended linearly.

<Performance on ice>
Based on feelings by professional test drivers, cornering performance and braking / driving performance on ice were evaluated as an overall performance index. In addition, this index | exponent has set the prior art example 1 to 100, and it is that performance is so good that a numerical value is high.

<Snow performance>
Based on the feeling of a professional test driver, the cornering performance and braking / driving performance on snow were evaluated as an overall performance index. In addition, this index | exponent has set the prior art example 1 to 100, and it is that performance is so good that a numerical value is high.

<DRY performance>
Based on feelings by professional test drivers, the cornering performance and braking / driving performance on the asphalt road surface of the test course were evaluated as an overall performance index. In addition, this index | exponent has set the prior art example 1 to 100, and it is that performance is so good that a numerical value is high.

<WET performance>
Based on the feeling of a professional test driver, the cornering performance and braking / driving performance on the WET road surface (water depth 1 mm) were evaluated as an overall performance index. In addition, this index | exponent has set the prior art example 1 to 100, and it is that performance is so good that a numerical value is high.

The obtained results are shown in Table 1.

  From the results shown in Table 1, comparing Conventional Example 1 and Comparative Examples 1 to 4, when the performance on snow and the performance on ice are improved, the DRY performance and WET performance are lowered, and when the DRY performance and WET performance are improved, the performance on snow and on ice The performance was degraded. In comparison with this, it was found that when the conventional example 1 and the examples 1 and 2 were compared, the DRY performance and the WET performance could be improved while maintaining the performance on snow and the performance on ice.

  In addition, when Example 1 and Example 2 are compared, Example 2 with a longer total sipe length formed in one block is better than conventional ones in all on-snow performance, on-ice performance, DRY performance, and WET performance. It turns out that it is improving.

It is a figure which shows the tread pattern which concerns on embodiment of this invention. It is an expansion perspective view of the block concerning the embodiment of the present invention. It is a figure which shows the sipe which concerns on Example 2 of this invention. It is a figure which shows the sipe which concerns on the comparative example 1 of this invention. It is a figure which shows the sipe which concerns on the comparative example 2 of this invention. It is a figure which shows the sipe which concerns on the comparative example 3 of this invention. It is a figure which shows the sipe which concerns on the comparative example 4 of this invention. It is a figure which shows the sipe which concerns on the prior art example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Circumferential groove | channel 2 ... Cross-sectional groove | channel 3 (3L, 3C, 3R) ... Block 4 (4L, 4C, 4R) ... Sipe 10 ... Tread pattern

Claims (1)

In a pneumatic tire provided with a plurality of blocks formed by a plurality of main grooves intersecting each other in a tread, and at least one sipe having a wavy shape in the tire width direction is formed on the block.
The sipe is curved in the tire circumferential direction in the depth direction which is the tire radial direction, and the curve is opposite to the inner side and the outer side when the vehicle is mounted, with the tire equator line as a boundary. Pneumatic tire characterized by.

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