JP2008290521A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire having many sipes in the tire width direction at blocks of a tread surface in which an anti-eccentric wear characteristic is improved without damaging a water-discharging characteristic. <P>SOLUTION: This pneumatic tire is constituted so that a block 4 is formed at a tread surface 1 by a plurality of main grooves 2 extending in a tire peripheral direction and lateral grooves 3 in a tire width direction and a plurality of sipes 5 in the tire width direction are provided at these blocks 4 characterized in that a plurality of protrusions 6a, 6b each of which extends in the tire width direction are arranged at both sides of inner walls 5a, 5b of the sipe 5 so as to oppositely face each other, heights (h) of the protrusions 6a, 6b are set to be 25 to 50% of a groove width W of the sipe 5 and at the same time and a distance L between the adjoining protrusions in the sipe depth direction is more than 0.25 times and less than 2 times of the groove width W of the sipe 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which drainage is improved as well as uneven wear resistance in a tire provided with a sipe in a tire width direction on a block formed on a tread surface.

  In general, tires with a block-based pattern on the tread surface, such as studless tires for running on icy and snowy roads, are braked on icy and snowy roads by increasing the edge effect by providing many sipes in the tire width direction on the block. -Drive performance is improved. However, if a large number of sipes in the tire width direction are formed on the block, the rigidity of the block is lowered, and there is a problem that uneven wear is likely to occur due to the collapse of the small blocks divided by the sipes.

As a measure for preventing uneven wear of such a small block, Patent Document 1 proposes that a plurality of protrusions are provided alternately in the depth direction on both sides of the sipe inner wall surface so that these protrusions mesh with each other. . However, if a plurality of protrusions are engaged with each other, the small block collapse is suppressed and the effect of suppressing uneven wear is recognized, but the drainage performance deteriorates because the space volume in the sipe decreases. There was a problem.
JP 2000-177330 A

  An object of the present invention is to provide a pneumatic tire in which uneven wear resistance is improved without impairing drainage performance in a tire in which a large number of sipes in the tire width direction are provided on a tread surface block.

  A pneumatic tire according to the present invention that achieves the above-mentioned object forms a block with a plurality of main grooves extending in the tire circumferential direction on the tread surface and lateral grooves in the tire width direction, and a plurality of sipes in the tire width direction are formed on these blocks. A plurality of ridges extending in the tire width direction on both sides of the inner wall surface of the sipe so as to face each other, and the height h of the ridge is defined as the groove width of the sipe. The width L is set to 25 to 50% of W, and the distance L between the adjacent ridges in the sipe depth direction is set to 0.25 times or more and 2 times or less of the groove width W of the sipe.

  The width of the ridge in the sipe depth direction may be different between the ridges facing each other, and the top of the ridge may be flat. In addition, the extending direction of the protrusions may be parallel to the tread surface, and a narrow groove extending in the tire width direction may be formed on at least one of the sipe inner wall surfaces. The groove width W of the sipe is preferably 0.4 to 2.0 mm.

  The pneumatic tire of the present invention is arranged so that the ridges extending in the tire width direction face each other on both sides of the inner wall surface of the sipe, and the height h of these ridges is 25 to 50 of the groove width W of the sipe. Therefore, when the small block that sandwiches the sipe is about to deform, the ridges come into contact with each other to prevent the blocks from falling down, so that uneven wear is less likely to occur, and between the ridges adjacent in the sipe depth direction. The distance L is set to 0.25 times or more and 2 times or less of the groove width W of the sipe to secure the space volume in the sipe, so that the drainage can be maintained.

  FIG. 1 is a plan view showing an example of a tread pattern provided on a pneumatic tire according to an embodiment of the present invention.

  In FIG. 1, the tread surface 1 is provided with a plurality of main grooves 2 extending in the tire circumferential direction and a plurality of lateral grooves 3 in the tire width direction. A plurality of blocks 4 partitioned by are formed. In each block 4, two sipes 5 are formed so as to extend in the tire width direction, and the blocks 4 are divided into three small blocks 4a by the sipes 5. The number of sipes 5 and the shape of the tread in plan view are not limited to those shown in the drawing, and the number of sipes 5 may be two or more, and the shape in plan view may be a straight line, a curved shape, Either a zigzag shape or a wave shape may be used.

  As shown in FIG. 2, the sipe 5 has a groove width W and a sipe depth D, and a pair of protrusions 6a and 6b facing the inner walls 5a and 5b facing substantially parallel to both sides of the sipe 5 are tires. It is provided so as to extend in the width direction, and is provided in multiple stages at intervals in the sipe depth direction. A narrow groove 7 is provided on the inner wall surface of the sipe between the ridges 6a and 6a that are separated in the sipe depth direction so as to extend in the tire width direction.

  As described above, the protrusions are provided on both sides of the sipe inner wall so as to face each other, so that uneven wear can be prevented in order to prevent the small block from falling down. Further, by arranging the protrusions facing each other with a distance L in the sipe depth direction, it is possible to secure a space and improve drainage.

  In the present invention, the height h of the protrusions 6a and 6b is set to 25 to 50% of the groove width W of the sipe 5, and preferably 40 to 45%. By setting the height of the ridge in this way, when the small block 4a is deformed, the ridges 6a and 6b facing each other are prevented from coming into contact with each other to prevent the small block from falling excessively.

  Further, the distance L between the ridges 6a, 6a adjacent to each other in the sipe depth direction is set to 0.25 times or more and 2 times or less of the groove width W of the sipe, preferably 0.5 times or more and 1 time or less. The lower limit is preferably 0.4 mm. By setting the distance L in such a range, a drainage channel can be secured in the sipe and the drainage can be improved.

  The groove width W of the sipe is preferably 0.4 to 2.0 mm, and more preferably 0.4 to 1.5 mm. If the groove width W is less than 0.4 mm, the drainage effect and edge effect of the sipe cannot be sufficiently obtained, and if it exceeds 2.0 mm, the block rigidity is greatly reduced. Further, the sipe depth D is preferably 4 mm or more and less than the depth of the main groove, and in the case of a passenger car tire, it may be 10 mm or less.

  The widths t and t 'when measured in the sipe depth direction of the ridges 6a and 6b may be the same or different from each other, but are preferably different from each other. . By making the widths t and t ′ different, when the block collapses and deforms, it can always be in a contact state regardless of the magnitude of the deformation. As the difference between the widths t and t ′, one is preferably 1.1 to 1.5 times larger than the other. The positions of the protrusions 6a and 6b facing each other may be the same position or may be slightly shifted in the sipe depth direction.

  The cross-sectional shape of the protrusions 6a and 6b is not particularly limited, and for example, a rectangular shape, a trapezoidal shape, a saw shape, a track shape, a semicircular shape, a semielliptical shape, and the like can be preferably exemplified. Further, the shape of the tops of the ridges 6a and 6b is not particularly limited, but it is preferable that they are parallel planes so as to maximize the mutual contact area. When the cross-sectional shape of the ridges 6a and 6b is semicircular or semi-elliptical, it is preferable to make the shape of the apex facing each other flat.

  Between the ridges 6a, 6a adjacent to each other in the sipe depth direction, the narrow groove 7 may be provided so as to extend in the tire width direction as shown in the embodiment. By providing this narrow groove 7, drainage can be further improved.

  The extending direction of the ridge may be parallel to the tread surface or may be inclined as long as it is in the tire width direction. That is, it may be extended parallel to the tread surface as in the ridge 6b illustrated in FIG. 3, or may be extended so as to be inclined with respect to the tread surface as in the ridge 6a. Good. Moreover, although a pair of protrusion 6a, 6b which mutually opposes may be formed so that it may extend in parallel mutually, you may form so that the mutual extension direction may cross | intersect. When the ridges 6a and 6b are arranged so that the extending directions intersect with each other, even if the deformation of the small block 4a increases, the ridges 6a and 6b can always be brought into contact with each other, so that the collapse of the block can be suppressed. In addition, the drainage can be further improved to ensure the maintenance of the space.

  When the extending direction of the ridge is inclined with respect to the tread surface, the inclination angle α is preferably in the range of 20 to 70 °. By making the inclination angle α in such a range, the above-described effect when the inclination is performed can be satisfactorily exhibited.

  The method of forming the above-described protrusions on both sides of the inner wall surface of the sipe can be formed simultaneously with the sipe at the time of tire vulcanization molding by providing a groove on the surface of the blade (sipe molding blade) forming the sipe, for example. it can. Further, a long hole corresponding to the shape of the ridge is formed in the blade, and after the tire vulcanization molding, the ridge is formed by cutting the rubber filling the long hole when the blade is pulled out.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  With the tire size 205 / 55R16 and the block pattern of FIG. 1 and the groove width W of the sipe being 0.8 mm, the presence or absence of ridges on the wall surface in the sipe, the height h of the ridge, Four types of pneumatic tires (Example 1, Comparative Examples 1 to 3) with different distances L between the strips as shown in Table 1 were produced.

  The obtained four types of pneumatic tires were evaluated for WET road surface running performance and uneven wear resistance by the following measurement methods.

[WET road running]
A pneumatic tire was mounted on a rear-wheel drive passenger car having a displacement of 2000 cc, and a lap time (second) was measured when going around a wet circular path with a radius of 100 m at a speed of 40 km / h.

[Uneven wear resistance]
A pneumatic tire was mounted on a rear-wheel drive passenger car having a displacement of 2000 cc, and the uneven wear amount (mm) at the edge of the small block after traveling 10,000 km was measured.

It is a top view which illustrates the tread pattern of the pneumatic tire which consists of an embodiment of the present invention. It is the principal part perspective view which looked at the sipe provided in the pneumatic tire of this invention from the tire width direction. It is a principal part perspective view which expands and shows other embodiment of the sipe provided in the pneumatic tire of this invention from a sipe center surface.

Explanation of symbols

1 tread surface 2 main groove 3 transverse groove 4 block 5 sipe 5a, 5b sipe inner wall surface 6a, 6b ridge 7 narrow groove

Claims (6)

In a pneumatic tire in which a block is formed by a plurality of main grooves extending in the tire circumferential direction on the tread surface and a lateral groove in the tire width direction, and a plurality of sipes in the tire width direction are provided on these blocks.
A plurality of ridges extending in the tire width direction are arranged on both sides of the inner wall surface of the sipe so as to face each other, and the height h of the ridge is 25 to 50% of the groove width W of the sipe. In addition, a pneumatic tire in which the distance L between the adjacent ridges in the sipe depth direction is 0.25 times or more and 2 times or less the groove width W of the sipe.   The pneumatic tire according to claim 1, wherein a width of the ridge in a sipe depth direction is different between the ridges facing each other.   The pneumatic tire according to claim 1 or 2, wherein a top portion of the protrusion is flat.   The pneumatic tire according to claim 1, 2 or 3, wherein the extending direction of the ridge is parallel to the tread surface.   The pneumatic tire according to any one of claims 1 to 4, wherein a narrow groove extending in a tire width direction is formed on at least one of the sipe inner wall surfaces.   The pneumatic tire according to any one of claims 1 to 5, wherein a groove width W of the sipe is 0.4 to 2.0 mm.

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