JP2011162022A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire particularly improved in uneven wear resistance of blocks dividingly formed in the vicinity of a tire equator surface, without deteriorating performance on ice. <P>SOLUTION: Block division is performed by disposing, on a tread surface 1, a plurality of circumferential grooves extended in a tread circumferential direction; and a plurality of lateral grooves extended in a tread width direction across these circumferential grooves. A sipe 10 located close to the tire equator surface and a sipe 11 located close to a tread end, are respectively disposed on the blocks 7 interposing therebetween the central circumferential groove 2 located in the vicinity of the tire equator surface. The sipe 10 close to the tire equator surface is extended with a curved portion in a depth direction. In the sipe 11 close to the tread end, the extending form thereof in the depth direction is formed identical to the tread surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, in particular, a small truck tire, and particularly proposes a technique for achieving both high performance on ice and uneven wear resistance at a high level.

Many so-called studless tires are used as pneumatic tires for running on icy and snowy road surfaces.
Studless tires usually have a plurality of blocks defined on the tread tread surface, and each block is provided with a plurality of sipes having an extending component in the tread width direction and an extending component in the tire radial direction. By increasing the edge effect of the tread on the icy and snowy road surface, excellent running performance on the icy and snowy road surface can be exhibited.

  On the other hand, when the number of sipes formed on the block surface is increased, the rigidity of the block divided parts divided by the sipes is reduced, and the amount of collapse of each block divided part increases, resulting in an increase in the entire block. As a result, the ground contact area is reduced and steering stability and the like are lowered, and uneven wear due to an increase in the amount of change in the block is inevitably generated.

  For this reason, for example, in Patent Document 1, 2D sipes are formed in the blocks in the center land portion partitioned by the center main grooves, and 2D sipes are respectively provided in the second block rows adjacent to the outer sides in the tire width direction of the center main grooves. A technology that effectively balances performance on ice and snow and dry / wet performance is proposed by forming 3D sipes in the shoulder block rows that are formed respectively and adjacent to the outside of the shoulder main groove in the tire width direction. ing.

  However, even with the tire described in Patent Document 1, the block of the center land portion formed with the 2D sipe has lower block rigidity than the block of the shoulder block row formed with the 3D sipe. There was a risk of wear.

  In addition, for example, in FIGS. 4 (a) and 4 (b), when the tires are assembled on a light truck, the contact length of the tread surface when empty and loaded is shown schematically. At times, the ground contact length of the blocks 15 in the shoulder block row is shortened, and particularly such tires support the weight of the vehicle at the center land, and a strong circumferential shear force is applied to the blocks in this region during rolling. As a result, the block 14 in the center land portion has insufficient block rigidity and increases the amount of slip, which may also cause local wear.

International Publication No. 2006/022120 Pamphlet

  Therefore, the present invention is to provide a pneumatic tire in which uneven wear resistance of a block formed in the vicinity of the tire equatorial plane is improved without reducing on-ice performance.

  The pneumatic tire according to the present invention is configured by disposing a plurality of circumferential grooves extending in the tread circumferential direction and a plurality of lateral grooves extending in the tread width direction across the circumferential grooves on the tread surface. Each block located across the central circumferential groove located near the tire equatorial plane is provided with a sipe located on the tire equatorial plane side and a sipe located on the tread end side, The sipe on the tire equatorial plane side extends with a bent portion in the depth direction, and the sipe on the tread end side is formed in the same manner as the tread tread surface in the depth direction. is there.

  Here, the circumferential groove and the lateral groove can be extended not only in a linear extending form but also in a zigzag form, a wave form, a crank form, etc., and are constituted by a plurality of circumferential grooves and transverse grooves. The shape of the development flat part of the block can be a square, a parallelogram, or the like, or a polygonal different shape, and the size of the block, the number of arrangement, etc. can be appropriately selected as required.

  In such a tire, preferably, the sipe has an amplitude in the tread width direction on the tread surface, and at least one end portion opens into a circumferential groove or a lateral groove.

  In the pneumatic tire according to the present invention, the sipe on the tire equatorial plane side of each block located across the central circumferential groove located near the tire equatorial plane extends with a bent portion in the depth direction, Compared with the tread surface extending in the same direction as the tread surface, the sipe has a zigzag unevenness in the sipe depth direction with respect to the generation of a strong tread circumferential shear force during rolling. Since it will support each other, the circumferential shear deformation of the block will be suppressed, so ensure sufficient rigidity of the block that supports the weight of the small truck, especially near the tire equatorial surface of the tread surface, It is possible to effectively reduce the amount of slip due to the block collapse deformation, and as a result, it is possible to improve uneven wear resistance.

  In addition, the sipe on the tread end side is formed in the same way as the tread surface in the depth direction, so that the tread end side is grounded compared to the tire equatorial plane side of each block located near the tire equatorial plane. It is a low pressure area (whether it is empty or loaded), and the sipe that has a bent part in the depth direction in that area collapses and deforms to obtain a scratching effect on the road surface on ice. It is possible to maintain the on-ice performance by arranging the sipe that is easy to arrange on the tread tread and making the edge component efficiently.

  The sipe is located near the tire equator plane, with the tire equatorial plane side extending with a bent portion in the depth direction and the tread end side being formed in the same manner as the tread tread surface in the depth direction. Different sipe functions can be divided into both side blocks adjacent to the central circumferential groove, and both on-ice performance and wear resistance can be improved.

It is a partial development view of a tread pattern showing one embodiment of a pneumatic tire of the present invention. FIG. 2 is an enlarged perspective view of a part showing blocks in the tread pattern shown in FIG. It is a partial expanded view of a part of a tread pattern showing a conventional pneumatic tire. It is each schematic which shows the contact length of the tread tread surface at the time of an empty vehicle, and (b) the tread tread surface contact length at the time of loading when a tire is assembled | attached to a light truck.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a partial development view of a tread pattern showing one embodiment of the pneumatic tire of the present invention, and FIG. 2 is an enlarged perspective view of a part showing blocks in the tread pattern shown in FIG.
Here, the reinforcing structure inside the tire is the same as that of a general radial tire or bias tire, and therefore illustration is omitted.

In the figure, reference numeral 1 denotes the entire tread surface. The tread surface 1 includes a plurality of circumferential grooves extending in the tread circumferential direction. In the figure, each of the central circumferential groove 2 and the central circumferential groove 2 on the tire equator surface. A side circumferential groove 3 adjacent to the side portion is disposed.
Between the two circumferential grooves adjacent to each other, in the figure, between the central circumferential groove 2 and the lateral circumferential groove 3, the center land portion 4 and between the lateral circumferential groove 3 and the tread side edge, the respective shoulder land portions. Divide 5.

  In the center land portion 4, a plurality of center blocks 7 are defined by transverse grooves 6 that extend across the center land portion 4 and extend in the tread width direction and open to the respective central circumferential grooves 2 and side circumferential grooves 3.

  In the shoulder land portion 5, a plurality of shoulder blocks 9 are defined by the lateral groove 8 that extends across the shoulder land portion 5 in the tread width direction and opens at the side circumferential grooves 3 and the tread side edges.

  In this pneumatic tire, the center block 7 is further provided with openings in the circumferential grooves 2 and 3 of the sipe 10 located on the tire equatorial plane side and the sipe 11 located on the tread end side, respectively. 10 extends in a zigzag shape in the tread width direction and extends in a so-called three-dimensional sipe (also referred to as a 3D sipe) having a bent portion in a zigzag shape in the depth direction. Is an extension form in the depth direction, and the opening to the tread tread extends in the form of, for example, a corrugated shape, zigzag shape, straight line, etc. These are formed by so-called two-dimensional sipes (also referred to as 2D sipes), and each sipes 10 and 11 end near the center of the block 7 in the figure.

  In such a tire, when the tire rolls on an icy and snowy road surface, each of the circumferential grooves 2 and 3 and the lateral grooves 6 and 8 causes the skid resistance, driving performance and braking under the action of the groove edges. It contributes to each improvement in performance, and in particular, the central circumferential groove 2 can improve the drainage performance on the road surface on ice near 0 ° C.

Since each sipe 10 and 11 has a so-called edge effect in which the sipe edge bites into the snowy and snowy road surface and increases the frictional force between the tread tread surface 1 and the road surface, the driving force and control in the direction perpendicular to the extending direction of the sipe. An increase in power and the like can be brought about.
In addition, the sipe itself sucks and removes a thin water film generated on the snowy and snowy road surface due to the rolling load of the tire, and sucks and removes it inside the sipe. By increasing the contact area, it can function to improve driving performance, braking performance and steering stability.
Therefore, such a tire has both the effect of the edge of the sipe opening edge and the effect of removing the water film of the sipe itself, thereby exhibiting excellent running performance on icy and snowy road surfaces.

Here, the circumferential grooves 2 and 3 and the lateral grooves 6 and 8 have, for example, a groove width in the range of 2 to 15 mm and a groove depth in the range of 6 to 15 mm. These grooves have not only a linear shape but also a zigzag shape and a wavy line. It can also be extended in the form of a circumferential groove such as a shape, a curved shape, or a crank shape.
For example, each of the sipes 10 and 11 can have a groove width of 0.3 to 1.5 mm, a groove depth of 4 to 11 mm, and a groove length of 2 to 30 mm.

  In such a tire, the sipe may be a linearly extending form, or the circumferential groove and the lateral groove may not be open at both ends, but preferably in the tread width direction on the tread surface, It has a zigzag shape, wave shape, crank shape, and other amplitudes, and at least one end opens into the circumferential groove 2, 3 or the lateral groove 6, and drives and brakes the vehicle on the ice surface. The increase in driving force and braking force can be ensured by the edge effect, which is the action of sipe on the road surface, and the opening at the time of rolling.

  Further, it is preferable to increase the number of sipes 11 located on the tread end side than the sipes 10 located on the tire equatorial plane side. With such a configuration, a strong circumferential shear force acts on the block during rolling. The scratching effect can be further enhanced while suppressing the number of sipes disposed on the side to be secured and ensuring the block rigidity.

Next, tires having a structure as shown in the figure and having a size of 235 / 65R16C 115 / 113R were prototyped and, as shown in Table 1, tires of various examples and comparative examples were changed. The turning performance and uneven wear resistance of the road surface on ice were measured for each of the tires 1 to 4.
In addition, since the comparative example tire does not require modification about structures other than the tread portion, it was assumed to be in conformity with the example tire.
In addition, the edge component per block in the table refers to a total value obtained by projecting the sipe edge length in the tire circumferential direction or the width direction.

[Turning performance on ice surface]
For each of the example tires and the comparative example tires 1 to 4, the rim of size 7J × 16 was assembled, the internal pressure was set to 475 kPa, the vehicle was mounted, and the lap time when running on a dedicated course was measured. It was done by The evaluation results are shown in Table 2.
In addition, it shows that it is excellent in the performance on an ice-snow road surface, so that the index | exponent in a table | surface is large.

[Uneven wear resistance]
Each of the example tires and comparative tires 1 to 4 is assembled to a rim having a size of 7 J × 16, attached to the vehicle with an internal pressure of 475 kPa, and after running on a dry road 10000 km with an empty vehicle, the central circumferential groove and the lateral circumference The wear ratio was calculated from the remaining groove of the groove and evaluated. The evaluation results are shown in Table 2.
In addition, it shows that it is excellent in the partial wear-proof performance, so that the value in a table | surface is small.

  From the results in Table 2, the example tires were able to improve the uneven wear resistance performance without reducing the turning performance of the road surface on ice with respect to the comparative tires 1 to 4.

DESCRIPTION OF SYMBOLS 1 Tread tread 2 Central circumferential groove 3 Side circumferential groove 4 Center land part 5 Shoulder land part 6,8 Horizontal groove 7 Center block 9 Shoulder block 10 Tire equatorial plane side sipe 11 Tread end side sipe

Claims (2)

In a pneumatic tire formed by dividing a block by disposing a plurality of circumferential grooves extending in the tread circumferential direction and a plurality of lateral grooves extending in the tread width direction so as to intersect the circumferential grooves on the tread surface. ,
Each block located across the central circumferential groove located near the tire equator plane is provided with a sipe located on the tire equator side and a sipe located on the tread end side,
Pneumatic, characterized in that the sipe on the tire equatorial plane side extends with a bend in the depth direction, and the sipe on the tread end side is formed in the same way as the tread surface in the depth direction. tire.   2. The pneumatic tire according to claim 1, wherein the sipe has an amplitude in a tread width direction on a tread surface, and at least one end portion is opened to a circumferential groove or a lateral groove.

Images