JP2545099B2 - Pneumatic tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pneumatic tire, and more particularly to a tread pattern of a heavy-duty pneumatic tire traveling on an icy and snowy road surface,
In addition, the present invention relates to a studless tire, particularly a pneumatic tire having improved water absorption performance and drainage performance when traveling on ice to improve ice performance and snow performance.

(Prior Art) In order to ensure the performance on ice and snow and the performance on ice, snow spike tires with spikes in the tread are used. However, in recent years, road damage due to spikes,
Due to dust pollution, studless tires that do not use spikes tend to be used instead of snow spike tires. Studless tires have worse performance on ice than spiked tires.

As a means for improving these drawbacks, there is a conventional one as shown in FIG. In FIG. 2, reference numeral 1 denotes a block-type studless pneumatic tire, and the pneumatic tire 1 has a plurality of blocks 6 defined by a plurality of circumferential grooves 3 and a plurality of lateral grooves 4 on a front portion of a tread 2.
Each block 6 is provided with a plurality of linear sipes 7 that are arranged to be inclined in the same direction at a substantially constant angle with respect to the tire circumferential direction. By arranging these sipes 7, the water film generated when the pneumatic tire 1 travels on an icy road surface is cut by the wall edge 7a of the sipe 7, thereby improving the drainage performance of the icy road. Is recognized as such.

(Problems to be Solved by the Invention) However, when the ground contact pressure is high, as in a heavy-duty pneumatic tire, the amount of water spilled out due to the melting of ice due to this high ground contact pressure is large, and a thick water film is formed. Therefore, there is a problem that the drainage performance is insufficient and sufficient freezing road traveling performance is not exhibited.

Therefore, the present invention is formed in a block row of the central area of the tread and each block of each block row adjacent to the side portion of the block row, and a plurality of blocks that are open to the circumferential groove at both outer ends of the block. An object of the present invention is to provide a pneumatic tire in which the cutting performance of a water film and drainage performance are improved by specifying the arrangement configuration of sipes, and the performance on ice and the performance on snow are improved.

(Means for Solving Problems) The inventors of the present invention, regarding the discharge of water generated on ice during traveling on a frozen road surface, the arrangement of the sipes and the drainage of the water by the sipes, the drainage speed, the circumferential groove, and the lateral direction. Various studies on the relationship with the water flowing through the groove, etc., regarding the proper efficient placement of sipes to each block of the block row in the central area of the tread and each block row adjacent to the side of the block row, in particular, It has been found that the drainage speed of water can be greatly improved by having a directionality with respect to the rotation direction of the tire and, for example, by providing a V-shaped sipe arrangement inclined with respect to the circumferential direction.

 Then, various researches were further repeated to reach the present invention.

That is, in the pneumatic tire according to the present invention, the front portion of the tread has a large number of blocks partitioned by a plurality of circumferential grooves and widthwise grooves, and in a pneumatic tire including a plurality of sipes in a block, , The blocks of the row of blocks in the central area of the tread are provided with a plurality of V-shaped sipes which are connected to the inside of the blocks and open to the circumferential groove at both outer ends. The sipe portion located inside the block is arranged to be grounded before the sipe portion located on the outer end side, and is formed in each block of each block row adjacent to the block row in the central area, Each of the plurality of linear sipes that open in the circumferential groove at both outer ends is supported by the sipe portion located inside the block when the tire is rotated. The feature is that it is arranged to be grounded before the ip part.

Here, having directivity with respect to the rotation direction of the tire means, for example, a V-shaped sipe having different drainage effects depending on the rotation direction of the tire.

The width of the sipe is preferably in the range of 0.3 mm to 2 mm. 0.
If the length is less than 0.3 mm, the drainage of water by the sipe is poor and the running performance on the frozen road surface is not exhibited sufficiently.If it exceeds 2 mm, the rigidity of the block section divided by the sipe is set to 3 mm to 2 mm. Is reduced, the edge effect of the edge of the block portion is reduced, and the snow performance is reduced.

The depth of sipe is 25% to 12 of the depth of the adjacent groove.
The range of 0% is preferable. 25% to 120% means that if it is less than 25%, the drainage performance is poor and the running performance on the frozen road surface is not sufficiently exerted, and if it exceeds 120%, the rigidity of the block portion as described above decreases, This is because the edge effect at the edge of the block portion is reduced and the snow performance is degraded.

(Function) While traveling on an icy road surface, a thick water film is generated in a portion where the tire contacts the ground due to a high ground contact pressure. However, in each block of the central area block row of the pneumatic tire of the present invention,
A plurality of V-shaped sipes whose both ends are open to the circumferential groove are provided, and each block of each block row adjacent to the side of the block row has the same V-shaped sipes. Since a plurality of substantially inverted “C” -shaped or V-shaped sipes having directionality are provided, the sharp edges on the surface of the block portion formed by these sipes cut the water film, The water in the cut water film is absorbed in the sipes, removed from the block surface, and discharged from the sipes after the tire has left the road surface.

The sipe in the block has directionality with respect to the tire rotation direction, is inclined with respect to the circumferential direction, and ends at the outer end of the block to open in the circumferential groove that partitions the block. The water inside moves along the sipe inclined with respect to the circumferential direction toward the outer end of the block as the tire rotates, and is discharged from the outer end into the circumferential groove that defines the block. Moreover, no backflow of water from the sipe end into the sipe occurs. Therefore, the cutting performance and drainage performance of the water film are high.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 is a diagram showing an embodiment of a pneumatic tire according to the present invention.

First, the configuration will be described. In FIG. 1, 11 is a pneumatic tire, and the pneumatic tire 11 is a tread 12
A large number of blocks 15 defined by four zigzag circumferential grooves 13 extending in the circumferential direction of the tire and a large number of lateral grooves 14 connecting two adjacent circumferential grooves 13 on the front portion 12a of
Are arranged in the circumferential direction to form five block rows 16a, 16b, 16c, 16d,
Has 16e. Block row 1 in central area of tread 12
Each block 15 of 6c has a plurality of pairs of sipes 18 which are connected to each other at the inner side 15a of the block and open to the circumferential groove 13 at both outer ends 15b so as to form a V shape. Of V-shaped sipe 18,
The opening end to the circumferential groove 13 is 18a, and both sides forming the V-shape are inclined by an angle θ with respect to the circumferential direction. Each block 15 of the block rows 16b and 16d on both sides of the block row 16c
Has a plurality of pairs of inverted C-shaped sipes 18 having a direction with respect to the tire rotation direction R. The sipe 18 has an inclination angle θ that inclines with respect to the circumferential direction and the block 15
It has an open end 18a which starts at the inner side 15a and ends at the outer end 15b and opens to the circumferential groove 13.

The inverted C-shaped sipes formed in each block 15 of the block rows 16b and 16d are also included in each block 1 of the block row 16c.
Similar to the sipe 18 formed in 5, it may be formed in a V shape.

Each sipe 18 is inside 15 of the block 15 as the tire rotates.
The sipe portion 18b located at a is arranged to be grounded before the sipe portion 18c located near the outer end 15b. Therefore, all the sipe pairs provided in the respective blocks 15 have the same directionality.

The width of the sipe is in the range of 0.3 mm to 2 mm, and the depth of the sipe is in the range of 25% to 120% of the depth of the circumferential groove 13. The configuration other than the above is the same as that of a normal pneumatic tire.

When the pneumatic tire 11 of the present invention travels on a frozen road surface,
A thick water film is generated between the block 15 and the road surface, but the thick water film is cut by the wall edges of the multiple sipes 18 provided in the block 15, and the water enters the sipes 18 and is discharged as the tire rotates. It The sipe pair has the same directionality in each block 15, and the sipe 18 of the block 15 in the central area is connected at the inner side 15a and is opened at both outer ends 15b into the circumferential groove 13 in a V shape. Further, in the other blocks 15, since the sipe pair has the same V-shape or inverted C-shape, the water inside the sipe is from the inner side 15a of the block 15 to the outer end 15b.
And flows into the circumferential groove 13 from the open end 18a of the sipe 18, and is rapidly discharged to the outside of the tire along with this flow. Also, water will not flow back into the sipe 18. Therefore, the running performance on the frozen road surface is significantly improved. Further, since the block 15 has an appropriate block rigidity, the snow performance is sufficiently maintained.

(Effect) As described above, according to the present invention, the same directionality with respect to the tire rotation direction is provided in each block of the block row in the central area and each block row adjacent to the side portion thereof. However, by disposing a plurality of sipes that open to the circumferential groove at both outer ends of the block, it is possible to enhance the cutting performance of the water film and the drainage performance, and the ice performance and the snow performance.

[Brief description of drawings]

FIG. 1 is a partial plan view showing an embodiment of a pneumatic tire according to the present invention. FIG. 2 is a partial plan view of a conventional tire. 11 …… Pneumatic tire 12 …… Tread 13 …… Circumferential groove 14 …… Lateral groove 15 …… Blocks 16a to 16e …… Block row 18 …… Sipe R …… Rotation direction θ …… Tilt angle

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasufumi Ichiki 3-5-5 Ogawa Higashi-cho, Kodaira-shi, Tokyo Bridgestone New Youth Center (56) Reference JP 61-16111 (JP, A) JP Sho 62-261109 (JP, A) JP-A-60-255506 (JP, A)

Claims (1)

(57) [Claims] 1. A pneumatic tire having a plurality of blocks defined by a plurality of circumferential grooves and a plurality of widthwise grooves on a front portion of a tread, the block having a plurality of sipes, and a central area of the tread. The blocks in the block row are connected to each other at the inner side of the block and open to the circumferential groove at both outer ends.
The V-shaped sipes are arranged such that when the tire rotates, the sipe portion located inside the block is grounded before the sipe portion located on the outer end side, and the block in the central area is provided. Each of a plurality of linear sipes that are formed in each block of each row adjacent to the row and that open in the circumferential groove at both outer ends of the block are positioned inside the block when the tire rotates. A pneumatic tire characterized in that the portion is arranged to come into contact with the ground before the sipe portion located on the outer end side of the block.