JP4156730B2 - Pneumatic tire with sipe on tread - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a tread with sipes.
[0002]
[Prior art]
In order to ensure the road surface grip performance of the tire when traveling on a wet road surface, F. Mr. Sipe invented a narrow cut or knife cut in the tread and was granted a US patent in 1922, but this technique is now widely used in the tire industry and is named after the inventor's name. It is called sipe or siping.
[0003]
[Problems to be solved by the invention]
A conventional sipe is a narrow plate-shaped cut, and if a sipe extending in the circumferential direction is arranged, the rigidity in the radial direction of the block and / or rib is lowered, and the steering stability performance of the tire is inevitably lowered. When the sipe extending in the radial direction is disposed, the rigidity in the circumferential direction of the block and / or the rib is lowered, and there is a drawback that the braking performance and the traction performance of the tire are inevitably lowered.
[0004]
The object of the present invention is to eliminate the above-mentioned problems of the prior art and to reduce the steering stability and traction of the tire inevitably caused by forming a sipe in the tread in order to secure the road surface grip performance of the tire. It is to suppress or prevent performance degradation.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a pneumatic tire of the present invention is a block formed by a plurality of circumferential grooves extending in parallel or substantially parallel to the circumferential direction and a plurality of inclined grooves extending in a direction inclined in the circumferential direction. And / or in a pneumatic tire with sipes on the ribs,
(1) the sipe is arranged to form a region surrounded by the sipe in the block and / or the rib;
(2) The sipe has a cross-sectional shape bent in a crank shape, the side close to the tread surface of the sipe is closer to the center of the block and / or the rib, and the side far from the tread surface is the outside of the block and / or the rib Arranged so that
This is a pneumatic tire.
[0006]
In order to achieve the above object, the pneumatic tire of the present invention comprises:
Of the region surrounded by the sipe formed in the block and / or the rib, the region near the center of the tread is horizontally long in the radial direction, and the region near the tread side is vertically long in the circumferential direction. Preferably there is.
[0007]
In order to achieve the above object, the pneumatic tire of the present invention comprises:
The ratio of the circumferential projection length a to the radial projection length b of the sipe forming the region surrounded by the sipe is 0.5 to 0.75 in the region near the center of the tread. 1.25 to 2.0 in the nearby region, and
The ratio of the circumferential projection length a to the radial projection length b of the sipe that forms the region surrounded by the sipe is 0.75 or more in the region near the midpoint between the tread central portion and the tread side portion. It is preferably 1.25.
[0008]
The pneumatic tire of the present invention has the above-described configuration, and in particular, since the sipe is disposed so as to form a region surrounded by the sipe in the block and / or the rib, The reaction force is also generated at the end of the sipe, and the tire performance is ensured even when driving on a road surface with a low coefficient of friction, such as an icy and snowy road surface.
[0009]
The pneumatic tire of the present invention is configured as described above, and in particular, the sipe has a cross-sectional shape bent in a crank shape, and the side close to the tread surface of the sipe is located near the center of the block and / or rib. However, since the side far from the tread surface is located outside the blocks and / or ribs, the blocks and / or blocks that are inevitably formed by forming sipes on the tread in order to ensure the road surface grip performance of the tire and / or Alternatively, it is possible to minimize the decrease in the rigidity of the ribs and make the ground pressure distribution uniform.
[0010]
In general, the front-rear and lateral forces within the tire's ground contact surface contribute to the front-rear direction of the area near the center of the tread and the side closer to the tread side. Contributes to direction force. The pneumatic tire of the present invention is configured as described above.
Of the regions surrounded by sipes formed on the blocks and / or ribs, the region near the center of the tread is horizontally long in the radial direction, and the region near the tread side is vertically long in the circumferential direction,
The ratio a / b of the circumferential projection length a to the sipe radial projection length b is preferably 0.5 to 0.75 in the vicinity of the tread central portion and 1.25 to 2.0 in the vicinity of the tread side portion. so,
More preferably, the ratio a / b of the circumferential projection length a to the sipe radial projection length b is 0.75 to 1.25 in the vicinity of the midpoint between the tread central portion and the tread side portion.
The sipe edge effect is maximized when driving on a road surface with a low coefficient of friction such as an ice-snow road surface.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, tires of examples and conventional tires according to the present invention will be described with reference to the drawings. The tire size is 175/70 R13.
[0012]
FIG. 1 is a tread pattern of a tire according to an embodiment of the present invention. The tire of the example includes five circumferential grooves 11, 12, 13 extending in parallel or substantially parallel to the circumferential direction, a number of inclined grooves 21, 22, 23 extending in a direction inclined in the circumferential direction, and circumferential grooves. 11, 12, 13 and ribs 31, 22, 23 formed by inclined grooves 21, 22, 23, and ribs 31 and blocks 41, 42 have sipes 51, 52, 53, 54, 55, 56. Is formed.
The sipe 51, 52, 53, 54, 55, 56 is arranged so as to form regions 61, 62, 63 surrounded by the sipe in the rib 31 and the blocks 41, 42.
The sipe 51, 52, 53, 54, 55, 56 has a cross-sectional shape bent in a crank shape as exemplarily shown in the AA cross-sectional view of FIG. 2, and the side close to the tread surface of the sipe is a block 41, 42 or the rib 31 is located near the center, and the side far from the tread surface is located outside the blocks 41, 42 or the rib 31.
Of the regions 61, 62, and 63 surrounded by the sipe, the region 61 near the center of the tread is horizontally long in the radial direction, and the region 63 near the tread side is vertically long in the circumferential direction.
The ratio a / b of the circumferential projection length a to the radial projection length b of sipe is 0.75 in the vicinity of the tread central portion and 1.85 in the vicinity of the tread side portion, and the tread central portion and the tread side portion It is 1.0 in the vicinity of the intermediate point.
As a modified embodiment based on the present invention, sipes may be arranged in blocks as shown in FIG.
[0013]
FIG. 4 shows a tread pattern of a conventional tire. FIG. 5 is a cross-sectional view taken along the line BB. Conventional tires are
The sipe 71, 72, 73, 74 is a sipe having a flat cross-sectional shape, not a cross-sectional shape bent in a crank shape as in the above-described embodiment, as exemplarily shown in FIG. Except that the regions 61, 62, and 63 surrounded by the sipe as in the example are not formed, the tire is almost the same as the tire of the above-described embodiment.
[0014]
The pneumatic tire of the example according to the present invention and the pneumatic tire of the conventional example were subjected to a comparative test of the steering stability performance of the tire and the traction performance during running on a snowy road.
A comparative test of the steering stability performance of a tire was performed by mounting a test tire on a 13 × 5 J rim, filling an internal pressure of 200 kpa, loading a load of 3.50 kN, and a speed of 50 km / h with respect to the slip angle. It measures the lateral force (side force).
The comparison test of traction performance on snowy roads was carried out by mounting the test tire on a 13 × 5J rim, filling 200 kpa of internal pressure, loading 3.50 kN, speed 40 km / h, and temperature minus 8 ° C. It measures traction when running on a snowy road under conditions.
[0015]
The comparison test result of the steering stability performance is shown in FIG. The horizontal axis is the slip angle, the vertical axis is the side force, and the unit is kN. The pneumatic tire of the above embodiment generates a greater lateral force (side force) than the conventional pneumatic tire.
As a result of the comparative test of the traction performance during running on a snowy road, the traction index of the pneumatic tire of the example according to the present invention was 115, assuming that the traction index of the pneumatic tire of the conventional example was 100.
[0016]
【The invention's effect】
From the above evaluation results, it can be seen that the pneumatic tires of the examples based on the present invention are superior in handling stability performance as compared with the conventional pneumatic tires, and are also excellent in traction performance when running on snowy roads. .
[Brief description of the drawings]
FIG. 1 is a tread pattern of a tire according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA.
FIG. 3 is a drawing showing a modified arrangement of sipes.
FIG. 4 is a tread pattern of a conventional tire.
FIG. 5 is a sectional view taken along line BB.
FIG. 6 is a graph showing the results of a comparison test of steering stability performance.
[Explanation of symbols]
11 circumferential groove 12 circumferential groove 13 circumferential groove 21 inclined groove 22 inclined groove 23 inclined groove 31 rib 41 block 42 block 51 sipe 52 sipe 53 sipe 54 sipe 55 sipe 56 sipe 61 sipe surrounded area 62 sipe surrounded Area 63 Area surrounded by sipe

Claims (4)

In a pneumatic tire provided with sipes on blocks and / or ribs formed by a plurality of circumferential grooves extending parallel or substantially parallel to the circumferential direction and a plurality of inclined grooves extending in a direction inclined in the circumferential direction,
(1) the sipe is arranged to form a region surrounded by the sipe in the block and / or the rib;
(2) The sipe has a cross-sectional shape bent in a crank shape, the side near the tread surface of the sipe is located near the center of the block and / or the rib, and the side far from the tread surface is the block and / or the rib. Arranged to be located outside the
A pneumatic tire characterized by that. Of the region surrounded by the sipe formed in the block and / or the rib, the region near the center of the tread is horizontally long in the radial direction, and the region near the tread side is vertically long in the circumferential direction. The pneumatic tire according to claim 1, wherein the pneumatic tire is provided. The ratio of the circumferential projection length a to the radial projection length b of the sipe forming the region surrounded by the sipe is 0.5 to 0.75 in the region near the center of the tread. The pneumatic tire according to claim 2, wherein the area in the vicinity is 1.25 to 2.0. The ratio of the circumferential projection length a to the radial projection length b of the sipe that forms the region surrounded by the sipe is 0.75 or more in the region near the midpoint between the tread central portion and the tread side portion. The pneumatic tire according to claim 3, wherein the pneumatic tire is 1.25.

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