JP2011088489A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make steering stability on an icy road or a dried road surface and uneven wear resistance performance compatible. <P>SOLUTION: On a block 5, a plurality of sipings 10, 11 extending in a direction crossing to the block 5 in a tire axial direction are provided in a tire circumferential direction with an interval. The sipings 10, 11 include a shallow and narrow siping 10 having width of 0.1-0.3 mm and depth of 0.5-0.6 times of the maximum depth of the lateral groove; and a deep and thick siping 11 having width of 0.3-1.0 mm and depth larger than the shallow and narrow siping 10. The shallow and narrow siping 10 and the deep and thick siping 11 are alternately formed in the tire circumferential direction, and further, the shallow and narrow siping 10 has both ends opened to both side surfaces of the block 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire capable of achieving high levels of both steering stability on an icy road and a dry road surface, uneven wear resistance, and the like.

  Tires suitable for winter use, including studless tires, have a block pattern in which a large number of blocks are divided in the tread portion. Further, in order to obtain a sufficient driving force on the icy road surface, siping extending in a direction crossing the block is provided in the block in the tire circumferential direction.

  Conventionally, various proposals have been made regarding siping. For example, Patent Document 1 below describes siping that uses a so-called Miura-folded three-dimensional curved surface in order to improve the running performance on an icy road. In such siping, even when a shearing force acts on the block, the siping surfaces firmly mesh with each other, and a large opening is suppressed. Therefore, the effect of enhancing the edge effect on the icy road and improving the wear resistance can be expected.

JP 2005-193867 A

  By the way, this kind of siping is usually vulcanized and molded as an inverted pattern by a knife blade formed on the molding surface of a tire vulcanizing mold. On the other hand, it is effective to increase the ground contact area in order to increase the driving force on the icy road. For this purpose, it is desired that the siping width, that is, the thickness of the knife blade is as small as possible.

  However, if the thickness of the knife blade is reduced, the knife blade may be deformed by the force received from the tire side during vulcanization, resulting in poor vulcanization. Also, considering the durability and rigidity of the knife blade, if the thickness of the knife blade is reduced, the height in the radial direction of the tire cannot be increased sufficiently, and as a result, the depth of siping must be reduced. In such siping, there is a tendency that the performance on ice significantly decreases due to wear, and the block cannot be flexibly deformed when traveling on a dry road, and uneven wear tends to occur.

  The present invention has been devised in view of the above-described problems, and siping formed in a block includes shallow narrow siping and deep siping having a width and depth larger than the shallow narrow siping. And, based on the fact that these are alternately formed in the tire circumferential direction, etc., to provide a pneumatic tire capable of achieving a high level of compatibility in handling stability on ice roads and dry road surfaces, uneven wear resistance performance, etc. The main purpose.

  The invention according to claim 1 of the present invention is a pneumatic tire in which a tread portion is provided with a plurality of blocks divided by vertical grooves extending in a tire circumferential direction and horizontal grooves extending in a direction intersecting with the vertical grooves. In the block, a plurality of sipings extending in a direction crossing the block in the tire axial direction are provided in the tire circumferential direction, and the siping has a width of 0.1 mm or more and less than 0.3 mm and a depth of the siping. Including shallow and narrow siping 0.5 to 0.6 times the maximum depth of the lateral groove, and deep and deep siping having a width of 0.3 mm to 1.0 mm and a depth larger than the shallow narrow siping, and The shallow narrow siping and the deep siping are alternately formed in the tire circumferential direction, and the shallow narrow siping is characterized in that both ends open on both side surfaces of the block.

  Further, according to a second aspect of the present invention, in the deep siping, one end of the deep siping is opened on one side surface of the block and the other end is terminated without opening on the other side surface of the block. This is a tire.

  The invention according to claim 3 is the pneumatic tire according to claim 1 or 2, wherein the length of the deep siping in the tire axial direction is 60 to 90% of the width of the block.

  The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the deep siping is formed on both sides in the tire circumferential direction and on the outermost side in the siping. .

  In the invention according to claim 5, the transverse groove is inclined at an angle θ1 of greater than 0 ° and not more than 45 ° with respect to the tire axial direction, and the deep siping is arranged with respect to the tire axial direction. And the angle θ2 is ± 3 ° of the angle θ1 of the transverse groove, and the shallow narrowing is inclined in the same direction as the transverse groove with respect to the tire axial direction, and The pneumatic tire according to any one of claims 1 to 4, wherein an angle θ3 is smaller than the angle θ2 of the deep siping.

  The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 5, wherein the shallow narrow siping extends linearly, and the deep siping includes a zigzag portion.

  In the block of the pneumatic tire of the present invention, sipings extending in the direction transverse to the tire axial direction are spaced apart in the tire circumferential direction. The siping has a width of 0.1 mm or more and less than 0.3 mm and a depth of 0.5 to 0.6 times the maximum depth of the lateral groove, and a width of 0.3 mm or more and 1.0 mm or less and And deep siping having a depth larger than the shallow narrow siping. For this reason, shallow siping that provides an edge effect while securing the contact area and deep siping that improves the actual contact area by bending the block are arranged in a well-balanced manner, and steering stability on ice and dry roads is improved. improves. Moreover, since the shallow narrow siping is open on both side surfaces of the block, the edge length is further secured to improve the handling stability on the icy road.

It is an expanded view of the tread part of the pneumatic tire of this embodiment. It is a perspective view which shows the block of this embodiment. It is the elements on larger scale which show the block of this embodiment. It is an expanded view of the tread part which shows other embodiment. It is an expanded view of the tread part which shows a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread portion 2 of a pneumatic tire (not shown) according to the present embodiment. In this embodiment, a studless tire for a passenger car is illustrated, and the tread portion 2 is provided with a plurality of vertical grooves 3 extending in the tire circumferential direction and horizontal grooves 4 extending in a direction intersecting with the vertical grooves 3. As a result, the tread portion 2 is divided into a plurality of block rows 6 (7 rows in this example) in which the blocks 5 are arranged in the tire circumferential direction.

  The longitudinal groove 3 of this embodiment extends substantially linearly. Such vertical grooves 3 exhibit excellent drainage performance, and can suppress unstable behavior such as vehicle wobbling or single flow during braking. However, the vertical groove 3 is not limited to such a shape, and may be formed in various shapes such as a zigzag shape or a wave shape.

  The groove width Wo of the vertical groove 3 is not particularly limited, but is preferably 1.5% or more, more preferably 3.5% or more of the tread width TW in order to improve drainage or snow drainage performance. Further, in order to ensure steering stability on a dry road surface or an ice road surface, the groove width Wo of the vertical groove 3 is preferably 8.0% or less, more preferably 5.0% or less of the tread width TW.

  The tread width TW is determined as a distance in the tire axial direction between the ground contact ends Te and Te of the tread portion 2. Further, the contact end Te is the most tire axial direction of the tread portion in a state where a normal load is applied to a normal tire in which the tire is properly assembled and filled with a normal internal pressure and the camber angle is set to a flat surface with a camber angle of 0 degrees. Determined as the outer ground end.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA. For ETRTO, “Measuring Rim”. In addition, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based, and is “maximum air pressure” for JATMA, and “TIRE” for TRA. The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” if it is ETRTO. Furthermore, the “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based, and is “maximum load capacity” for JATMA and “TIRE” for TRA. The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is “LOAD CAPACITY” if it is ETRTO.

  As shown in FIG. 3, the lateral groove 4 preferably extends linearly and is inclined at an angle θ1 of greater than 0 ° and less than 45 ° with respect to the tire axial direction. When the angle θ1 exceeds 45 ° with respect to the tire axial direction, the traction performance on an icy road tends to decrease during straight running. From such a viewpoint, the angle θ1 of the lateral groove 4 is preferably 35 ° or less, more preferably 25 ° or less.

  The width W1 of the lateral groove 4 is preferably 1.5% or more of the tread width TW, more preferably 2.5% or more, and preferably from the viewpoint of ensuring drainage or snow drainage performance and maintaining the ground contact area. Is preferably 5.5% or less, more preferably 4.5% or less.

  Further, as shown in FIG. 2, the groove depths D0 and D1 of the vertical grooves 3 and the horizontal grooves 4 are not particularly limited. However, if the groove depth is too large, the rigidity of the block 5 is lowered. Conversely, if the groove depth is too small, drainage or snow removal performance tends to deteriorate. In the case of a passenger vehicle tire as in the present embodiment, the depths D0 and D1 of the longitudinal grooves 3 and the lateral grooves 4 are each preferably 6.0 to 10.0 mm.

  As shown in FIG. 1, each block 5 is provided with a plurality of sipings 7 (5 or 3 in this embodiment) extending in the tire circumferential direction extending in a direction crossing the block 5 in the tire axial direction. The The siping 7 has a cut shape with a small groove width. This notch can be closed by the action of an external force (such as a shearing force) during travel. For this reason, it is clearly distinguished from the vertical groove 3 and the horizontal groove 4 that cannot be closed and are involved in drainage performance.

  As shown in FIGS. 2 and 3, the siping 7 of the present embodiment has a width W3 of 0.1 mm or more and less than 0.3 mm and a depth D3 of 0.5 to 0. 0 which is the maximum depth D1 of the lateral groove 4. A 6-times shallow narrow siping 10 and a deep siping 11 having a width W2 of 0.3 mm to 1.0 mm and a depth D2 larger than the shallow narrow siping 10 are configured.

  When the width W3 of the shallow and narrow siping 10 is less than 0.1 mm, the knife blade (not shown) formed on the molding surface of the tire vulcanizing mold is deformed by the force received from the tire being vulcanized. There is a risk of failure. On the other hand, if the width W3 exceeds 0.3 mm, the ground contact area is reduced, and the steering stability on the icy road and the dry road may be deteriorated. In addition, when the depth D3 of the shallow narrow siping 10 is less than 0.5 times the maximum depth D1 of the lateral groove 4, the edge effect is not exhibited, and the steering stability on the icy road may be deteriorated. Due to wear, ice performance is significantly reduced. On the other hand, when the depth D3 exceeds 0.6 times the maximum depth D1, the knife blade is deformed by the force received from the tire being vulcanized, which may cause poor vulcanization. That is, by limiting to the above numerical range, the shallow narrow siping 10 having a narrow width suppresses a decrease in the contact area, and maintains steering stability on a dry road and particularly an ice road. Further, since the knife blade can withstand the force received from the tire being vulcanized, poor vulcanization can be reduced.

  In addition, if the width W2 of the deep siping 11 is less than 0.3 mm, the block 5 cannot be flexibly deformed, and uneven wear may easily occur. On the other hand, if the width W3 exceeds 1.0 mm, the contact area may be reduced, and the steering stability on the icy road and the dry road may be deteriorated. That is, the deep siping 11 having a large depth can deform the block 5 flexibly and make the ground contact pressure on the block tread uniform. This suppresses the occurrence of uneven wear. If the depth D2 of the deep siping 11 is too large, the block rigidity may be excessively lowered and the steering stability may be deteriorated. From such a viewpoint, the depth D2 of the deep siping 11 is preferably 0.70 to 0.90 times the maximum depth D1 of the lateral groove 4.

  Furthermore, the shallow narrow siping 10 and the deep siping 11 are alternately formed in the tire circumferential direction. For this reason, it is possible to make the block rigidity uniform and suppress the occurrence of uneven wear, and improve the steering stability on the dry road and the ice road in a balanced manner by increasing the edge effect of the siping 7 and the actual contact area. Can do.

  As shown in FIGS. 1 and 2, both ends 10e and 10e of the shallow narrow siping 10 are opened on both side surfaces 5A and 5B of the block 5. Thereby, an edge effect increases and the traction performance on an icy road is improved. Moreover, since the shallow narrow siping 10 extends linearly, productivity is improved as compared with the case where the shallow narrow siping 10 is a zigzag siping.

  Further, as shown in FIG. 2, the deep siping 11 has one end 12 opened on one of the side surfaces 5A or 5B of the block 5 and the other end 13 opened on the other side of the side surfaces 5A or 5B of the block. A shape that terminates without being desirable.

  In particular, the first deep siping 11A having one end 12A opened on one side surface 5A of the block 5 and the other end 13A terminated without opening on the other side surface 5B of the block, and one end 12B on the block 5 The second deep siping 11B that opens to the other side surface 5B and terminates without the other end 13B opening to the one side surface 5A of the block is alternately formed in the same block through the shallow narrowing siping 10. It is desirable that As a result, the openings 11c of the side surface 5A or 5B of the block 5 due to the deep siping 11 are distributed and arranged on the one side surface 5A and the other side surface 5B of the block 5, so that the block rigidity is made uniform. Further, the occurrence of uneven wear can be suppressed more effectively.

  Further, if the length L3 of the deep siping 11 in the tire axial direction is too large, the block rigidity tends to be excessively lowered. On the other hand, if it is too small, the block 5 cannot be flexibly bent, and there is a tendency that uneven wear cannot be sufficiently suppressed. From this point of view, the length L3 of the deep siping 11 in the tire axial direction is preferably 60% or more, more preferably 70% or more, and preferably 90% or less, more preferably the width L1 of the block 5. Is preferably 80% or less.

  Further, as shown in FIG. 3, it is desirable that the deep siping 11 has a shape having a straight portion 14 that extends linearly and a zigzag portion 15 that continues to the straight portion 14 and extends zigzag to the other end 13. . Since the edge effect is further increased by providing the zigzag portion 15, not only the traction performance on the icy road but also the large deformation of the sipe is suppressed even during a turn and the steering stability is improved.

  Further, the deep siping 11 is preferably formed on both sides in the tire circumferential direction and on the outermost side in the siping 7. As a result, the block ends on both sides in the tire circumferential direction where a large shearing force acts during driving and braking of the tire can be sufficiently bent, and a great traction effect can be exhibited.

  Further, the deep siping 11 is inclined in the same direction as the lateral groove 4 with respect to the tire axial direction, and the angle θ2 with respect to the tire axial direction is ± 3 ° of the angle θ1 of the lateral groove 4, that is, substantially equal to the lateral groove 4. Are preferably parallel. Thereby, the rigidity in the tire circumferential direction of the block end piece 16 sandwiched between the deep siping 11 and the lateral groove 4 is made uniform in the width direction, and uneven wear or the like starting from the block end piece 16 can be effectively suppressed. The angle with respect to the tire axial direction means the angle between the center line of the siping or groove on the block plane and the tire axial direction when the siping or groove is linear. In addition, in the case of the deep siping 11 of this embodiment having a zigzag portion, the angle with respect to the tire axial direction of the straight line 17 formed by connecting the centers of the amplitudes of the zigzag portion.

  Further, it is desirable that the shallow narrow siping 10 is inclined in the same direction as the lateral groove 4 with respect to the tire axial direction, and an angle θ3 with respect to the tire axial direction is smaller than an angle θ2 of the deep siping 11. . Desirably, the angle θ3 is preferably parallel to the tire axial direction. Thereby, it is possible to improve the traction performance while suppressing the occurrence of uneven wear.

  Further, the spacing pitch D in the tire circumferential direction of the siping 7 is not particularly limited, but if it is too small, the rigidity of the block 5 is reduced and rubber chipping or the like tends to occur. There is a tendency to lower. From such a viewpoint, the spacing pitch D is preferably 2.0 mm or more, more preferably 3.0 mm or more, and 10.0 mm or less, more preferably 5.0 mm or less.

  Further, although not particularly limited, as a function of a general studless tire, the tread portion 2 has a land ratio of 67 to 75%, and at least the tread rubber that contacts the road surface is JIS at room temperature (23 ° C.). It is desirable that the rubber composition has a durometer A hardness of 42 to 50 degrees.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.

  In order to confirm the effect of the present invention, a 195 / 65R15 passenger car studless tire having the pattern shown in FIG. 1 and based on the specifications shown in Table 1 was prototyped. Each test tire was mounted on a four-wheel drive passenger car with a displacement of 2000 cc at a rim of 6 × 15 and an internal pressure of 200 kPa, and the steering stability performance and uneven wear performance on icy roads and dry roads were tested. The parameters other than those shown in Table 1 are all the same. The main common specifications are as follows.

Tread width TW: 170mm
Groove width Wo of vertical groove: 7.5mm
Groove depth Do: 10.0mm
Groove width W1: 4.5mm
Groove depth D1: 8.5 mm
Angle θ1: 10 ° with respect to tire axial direction of lateral groove
Deep siping width W2: 0.3mm
Deep siping depth D2: 8.0mm
Land ratio: 67% (Comparative Example 1)
The test method is as follows.

<Dry road / ice road handling stability>
In the above test vehicle, test driving on the dry road surface and icy road surface of the tire test course with one driver each, and the characteristics related to steering wheel response, braking performance, driving performance, grip, etc. were compared with Comparative Example 1 by sensory evaluation of the driver. It was rated with a score of 100. The larger the value, the better.

<Uneven wear resistance>
Drive the dry asphalt road for 3000 km on the above test vehicle, and measure the difference in the amount of wear between one end and the other end of the block at each of the center, middle, and shoulder blocks (three in total) on the tire circumference. The average value was obtained. The results are displayed as an index with Comparative Example 1 as 100. The larger the value, the better.

<Presence / absence of vulcanization failure>
Each sample tire was manufactured, and the presence or absence of poor vulcanization of shallow and narrow siping was confirmed with the naked eye. Tires in which poor vulcanization was found in 5 or more locations were rejected.
Table 1 shows the test results.

  As a result of the test, it can be confirmed that the tire of the example significantly improved the running performance on the dry road and the ice road as compared with the comparative example. It was also confirmed that there was no problem with uneven wear performance and poor vulcanization.

2 Tread part 3 Vertical groove 4 Horizontal groove 5 Block 7 Siping 10 Shallow narrow siping 11 Deep siping

Claims (6)

A pneumatic tire provided with a plurality of blocks divided into a longitudinal groove extending in a tire circumferential direction and a lateral groove extending in a direction crossing the longitudinal groove in a tread portion,
In the block, a plurality of sipings extending in a direction crossing the block in the tire axial direction are spaced apart in the tire circumferential direction,
The siping includes a shallow and narrow siping having a width of 0.1 mm or more and less than 0.3 mm and a depth of 0.50 to 0.60 times the maximum depth of the lateral groove;
A deep siping having a width of 0.3 mm to 1.0 mm and a depth larger than the shallow narrow siping, and the shallow narrow siping and the deep siping are alternately formed in a tire circumferential direction,
In addition, the shallow narrow siping is a pneumatic tire characterized in that both ends open on both side surfaces of the block.   2. The pneumatic tire according to claim 1, wherein one end of the deep siping opens on one side of the block and the other end ends without opening on the other side of the block.   The pneumatic tire according to claim 1 or 2, wherein a length of the deep siping in a tire axial direction is 60 to 90% of a width of the block.   The pneumatic tire according to any one of claims 1 to 3, wherein the deep siping is formed on both sides in the tire circumferential direction and on the outermost side in the siping. The transverse groove is inclined at an angle θ1 of greater than 0 ° and less than 45 ° with respect to the tire axial direction,
The deep siping is inclined in the same direction as the transverse groove with respect to the tire axial direction, and the angle θ2 is ± 3 ° of the angle θ1 of the transverse groove,
The shallow shallow siping is inclined in the same direction as the transverse groove with respect to the tire axial direction, and an angle θ3 thereof is smaller than the angle θ2 of the deep siping. Pneumatic tires.   The pneumatic tire according to claim 1, wherein the shallow and narrow siping extends linearly, and the deep siping includes a zigzag portion.

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