JP5957496B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that achieves both on-ice performance and wear resistance.

  Conventionally, in order to improve the performance on ice, a pneumatic tire having a sipe provided on a block has been proposed. Such a pneumatic tire increases the frictional force on the icy road by a road surface scratching action (hereinafter referred to as “edge effect”) by the edge of the sipe.

  However, a block provided with sipes tends to have low rigidity and low wear resistance.

  For example, Patent Document 1 below is divided into a center region between the center main groove extending zigzag on both sides of the tire equator and a shoulder region outside the center main groove by narrow grooves smaller than the center main groove. A pneumatic tire having a plurality of blocks is proposed. This block is divided into irregularly shaped block pieces by a plurality of sipes. For this reason, the pneumatic tire of Patent Document 1 has room for further improvement in terms of compatibility between performance on ice and wear resistance.

JP 2009-190558 A

  The present invention has been devised in view of the above circumstances, and has as its main object to provide a pneumatic tire that achieves both on-ice performance and wear resistance by improving the arrangement of sipes. .

  The present invention provides a tread portion having a pair of center main grooves extending zigzag continuously in the tire circumferential direction on both sides of the tire equator, a center region between the pair of center main grooves, and each of the center main grooves. A pneumatic tire having a shoulder region on the outer side in the tire axial direction, wherein the center region and each shoulder region extend continuously in the tire circumferential direction and have a groove width smaller than the center main groove. And a plurality of blocks divided by a transverse groove extending in the tire axial direction, and at least one of the blocks is formed by a plurality of sipes, so that a small block piece and a width in the tire circumferential direction than the small block piece are provided. Are divided so as to include large block pieces, and among the blocks, the small block pieces and the large block pieces are alternately arranged in the tire circumferential direction. It is characterized by a door.

  In the pneumatic tire according to the aspect of the invention, it is preferable that the block includes three or more small block pieces.

  In the pneumatic tire of the present invention, it is desirable that the block has a pentagonal or hexagonal tread whose length in the tire circumferential direction is larger than the width in the tire axial direction.

  In the pneumatic tire of the present invention, the block includes a hexagonal block having a hexagonal tread surface, and the hexagonal block has a pair of convex portions projecting on both sides in the tire axial direction. It is desirable that each tip of the part is formed in the same small block piece.

  In the pneumatic tire of the present invention, it is preferable that the groove width of the lateral groove is larger than the groove width of the center main groove.

  In the pneumatic tire of the present invention, the narrow groove includes a center narrow groove provided between the pair of center main grooves, and the center narrow groove extends linearly on the tire equator. And a second center narrow groove extending zigzag on both outer sides of the first center narrow groove.

  In the pneumatic tire of the present invention, the narrow groove includes a shoulder narrow groove provided outside the center main groove in the tire axial direction, and the shoulder narrow groove includes a first shoulder narrow groove extending in a zigzag shape, It is desirable to include a second shoulder narrow groove extending linearly outside the first shoulder narrow groove in the tire axial direction.

  In the pneumatic tire of the present invention, the block includes a center block provided in the center region and a shoulder block provided in the shoulder region, and the shoulder block is in a tire axial direction than the center block. It is desirable to include a first shoulder block having a large width.

  In the pneumatic tire of the present invention, a ratio L1 / L2 between a width L1 of the large block piece in the tire circumferential direction and a width L2 of the small block piece in the tire circumferential direction is 3.0 to 5.0. Is desirable.

  The pneumatic tire of the present invention includes a pair of center main grooves extending in a zigzag manner continuously in the tire circumferential direction on both sides of the tire equator in the tread portion, a center region between the pair of center main grooves, and each center main groove. And a shoulder region on the outer side in the tire axial direction of the groove. Such a groove edge of the center main groove can effectively scratch the road surface and improve the performance on ice.

  The center region and each shoulder region are provided with a plurality of blocks that are divided into narrow grooves continuously extending in the tire circumferential direction and having a groove width smaller than the center main groove, and lateral grooves extending in the tire axial direction. Yes. At least one of the blocks is divided by a plurality of sipes so as to include a small block piece and a large block piece having a larger width in the tire circumferential direction than the small block piece. In each block, the small block pieces and the large block pieces are alternately arranged in the tire circumferential direction.

  Such a block improves the performance on ice, especially when traveling on ice, especially the edge of the small block piece scratches the road surface. In addition, since the small block pieces and the large block pieces are alternately arranged, the large block pieces effectively suppress excessive deformation of the small block pieces and suppress uneven wear of the blocks. Therefore, the performance on ice and the wear resistance are improved in a well-balanced manner.

It is an expanded view of the tread part of the pneumatic tire of this embodiment. It is AA sectional drawing of FIG. It is an enlarged view of the center area | region and shoulder area | region of FIG. It is an enlarged view of the 1st shoulder block of FIG. It is an enlarged view of the 1st center block of FIG. It is an expanded view of the tread part of the pneumatic tire of a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a tread portion 2 of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire 1 of the present embodiment is suitably used as a heavy duty pneumatic tire for winter, for example.

  As shown in FIG. 1, the tread portion 2 includes a pair of center main grooves 3 provided on both outer sides of the tire equator C, a center region 5 between the pair of center main grooves 3, and the center main grooves. A shoulder region 7 on the outer side in the tire axial direction of the groove 3 is provided.

  The center main groove 3 extends in a zigzag shape continuously in the tire circumferential direction. Such a center main groove 3 exhibits a frictional force in the tire circumferential direction when traveling on ice.

  The center main groove 3 has the largest groove width W1 among the grooves provided in the tread portion 2 extending continuously in the tire circumferential direction. The groove width W1 of the center main groove 3 is, for example, 2.5 to 5.0% of the tread ground contact width TW. Such a center main groove 3 balances the performance on ice and the performance on snow with good balance while maintaining the rigidity of the tread portion 2.

  The tread contact width TW is a distance in the tire axial direction between the tread contact ends Te and Te of the tire 1 in a normal state. The normal state is a state in which a tire is assembled on a normal rim (not shown) and filled with a normal internal pressure, and is not loaded.

  The “regular rim” is a rim determined for each tire in a standard system including a standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, ETRTO Then "Measuring Rim".

  The “regular internal pressure” is an air pressure determined by each standard for each tire in the standard system including the standard on which the tire is based. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO.

  The “tread contact end Te” is a contact position on the outermost side in the tire axial direction when a normal load is applied to the tire 1 in the normal state and the tire 1 contacts the plane with a camber angle of 0 °.

  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. “JATMA” indicates “maximum load capacity”, and TRA indicates “TIRE LOAD”. The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2, the groove depth d1 of the center main groove 3 is, for example, 10 to 25 mm in the case of a heavy duty pneumatic tire for winter.

  As shown in FIG. 1, the center region 5 and the shoulder region 7 include a narrow groove 10 extending continuously in the tire circumferential direction and having a groove width smaller than the center main groove 3, and a lateral groove 11 extending in the tire axial direction. A plurality of blocks 12 are provided.

  The narrow groove 10 includes, for example, a center narrow groove 15 provided between the pair of center main grooves 3 and 3 and a shoulder narrow groove 20 provided outside the center main groove 3 in the tire axial direction. .

  FIG. 3 shows an enlarged view of the center region 5 and the shoulder region 7. As shown in FIG. 3, the center narrow groove 15 includes, for example, a first center narrow groove 16 extending linearly and a second center narrow groove 17 extending zigzag. The first center narrow groove 16 is provided on the tire equator C, for example. For example, the second center narrow groove 17 is provided on the outer side in the tire axial direction of the first center narrow groove 16.

  The shoulder narrow groove 20 includes, for example, a first shoulder narrow groove 21 extending in a zigzag manner and a second shoulder narrow groove 22 extending linearly on the outer side in the tire axial direction of the first shoulder narrow groove 21.

  The groove width W2 of each of the narrow grooves 10 described above is preferably 0.3 times or more, more preferably 0.35 times or more, preferably 0.45 times or less, more preferably less than the groove width W1 of the center main groove 3. Is 0.4 times or less. Such a narrow groove 10 exhibits an excellent edge effect while maintaining the rigidity of the center region 5 and the shoulder region 7.

  As shown in FIG. 2, the groove depth d <b> 2 of each narrow groove 10 is preferably 0.5 to 0.7 times the groove depth d <b> 1 of the center main groove 3, for example. Such a narrow groove 10 maintains the rigidity of the center region 5 and the shoulder region 7 and improves the wear resistance.

  As shown in FIG. 3, each lateral groove 11 extends linearly along the tire axial direction. The lateral groove 11 includes a center lateral groove 25 provided in the center region 5 and a shoulder lateral groove 30 provided in the shoulder region 7.

  The center lateral groove 25 is a first center lateral groove 26 that communicates between the first center narrow groove 16 and the second center narrow groove 17, and a second center that communicates between the second center narrow groove 17 and the center main groove 3. The center lateral groove 27 is included.

  The shoulder lateral groove 30 is a first shoulder lateral groove 31 that communicates between the center main groove 3 and the first shoulder narrow groove 21, and a second that communicates between the first shoulder narrow groove 21 and the second shoulder narrow groove 22. Shoulder lateral grooves 32 are included.

  The groove width W3 of each lateral groove 11 described above is desirably larger than the groove width W1 of the center main groove 3, for example. The groove width W3 of the lateral groove 11 is preferably 1.65 times or more, more preferably 1.70 times or more, preferably 1.85 times or less, more preferably 1.80 times the groove width W1 of the center main groove 3. Is less than double. Such a lateral groove 11 exhibits an excellent snow column shearing force while maintaining the rigidity of the center region 5 and the shoulder region 7 and improves the performance on snow.

  As shown in FIG. 2, the groove depth d <b> 3 of each lateral groove 11 is preferably 0.5 to 0.7 times the groove depth d <b> 1 of the center main groove 3, for example. The lateral groove 11 of the present embodiment has, for example, the same groove depth as that of the narrow groove 10. Such a lateral groove 11 exhibits an excellent snow column shear force while maintaining the rigidity of the block 12.

  As shown in FIG. 3, the block 12 includes a center block 35 provided in the center region 5 and a shoulder block 40 provided in the shoulder region 7.

  The center block 35 includes, for example, a first center block 36 and a second center block 37.

  The first center block 36 is divided into, for example, a first center narrow groove 16, a second center narrow groove 17, and a first center lateral groove 26. The first center block 36 is, for example, a pentagonal block 45 having a pentagonal tread. The pentagonal block 45 has, for example, a protrusion 48 that protrudes inward or outward in the tire axial direction. The convex portion 48 of the first center block 36 of the present embodiment projects outward in the tire axial direction.

  The second center block 37 is divided into, for example, a second center narrow groove 17, a center main groove 3, and a second center lateral groove 27. The second center block 37 is, for example, a hexagonal block 46 having a hexagonal tread surface. The hexagonal block 46 of this embodiment has a pair of convex part 48 which protrudes in the both sides of a tire axial direction, for example.

  The shoulder block 40 includes, for example, a first shoulder block 41 and a second shoulder block 42.

  The first shoulder block 41 is divided into, for example, a center main groove 3, a first shoulder narrow groove 21, and a first shoulder lateral groove 31. The first shoulder block 41 is, for example, a hexagonal block 46 having a hexagonal tread surface.

  For example, the first shoulder block 41 desirably has a larger width in the tire axial direction than the first center block 36 and the second center block 37. Thereby, the rigidity of the shoulder area | region 7 is improved and the steering stability on ice is improved.

  The second shoulder block 42 is divided into, for example, a first shoulder narrow groove 21, a second shoulder narrow groove 22, and a second shoulder lateral groove 32. The second shoulder block 42 is, for example, a pentagonal block 45 having a pentagonal tread.

  For example, the second shoulder block 42 desirably has a smaller width in the tire axial direction than the first shoulder block 42. Such a second shoulder block 42 effectively enhances the wandering performance.

  FIG. 4 shows an enlarged view of the first shoulder block 41 of the present embodiment as a diagram for explaining the block 12. As shown in FIG. 4, the block 12 is divided by a plurality of sipes 50 so as to include a small block piece 51 and a large block piece 52 having a larger width in the tire circumferential direction than the small block piece 51. Yes. In the present specification, “sipe” is a cut having a width of about 1 mm or less, for example, and having a width of about 1 mm or less, and is distinguished from a drainage groove.

  In each block 12, the small block pieces 51 and the large block pieces 52 are alternately arranged in the tire circumferential direction. When such a block 12 travels on ice, the edge of the small block piece 51 that is relatively easily deformed effectively scratches the road surface, thereby improving the performance on ice. On the other hand, the large block piece 52 that is relatively difficult to deform can come into contact with the road surface on ice and prevent the contact area from decreasing. Moreover, since the small block pieces 51 and the large block pieces 52 are alternately arranged, the large block pieces 52 effectively suppress excessive deformation of the small block pieces 51 and suppress uneven wear of the blocks 12. Therefore, the performance on ice and the wear resistance are improved in a well-balanced manner. In order to further enhance the above-described effect, it is desirable that the block 12 has a length L4 in the tire circumferential direction that is greater than a width W4 in the tire axial direction.

  It is desirable that the small block piece 51 faces the large block piece 52 of the adjacent block through the narrow groove 10. In other words, it is desirable that the small block pieces 51 are arranged so as not to be arranged side by side with the small block pieces of other blocks via the narrow grooves 10. In the present embodiment, the entire area of the end portion 51 e of the small block piece 51 faces the large block piece 52. In such an embodiment, when turning, when the small block piece 51 is largely deformed in the tire axial direction, the large block piece 52 having high rigidity can effectively support the small block piece 51, and thus the small block The wear resistance of the piece 51 is improved.

  As shown in FIG. 1, in this embodiment, the end portions 51 e of the small block pieces 51 all face the large block pieces 52 of the adjacent blocks or the lateral grooves 11. The small block piece 51 facing the large block piece 52 can obtain the above-described effects. The small block piece 51 facing the lateral groove 11 forms the maximum width of the block, and since the deformation at the time of turning is small, the wear resistance is not lowered.

  As shown in FIG. 4, in the case of the hexagonal block 46, it is desirable that the tips 49 of the pair of convex portions 48 are formed on the same small block piece 51. In the present embodiment, each tip 49 of the pair of convex portions 48 is formed in a small block piece 51 located at the center of the block 12 in the tire circumferential direction. Thereby, the chipping | blocking of the block which started from the front-end | tip 49 of the convex part 48 is suppressed effectively.

  FIG. 5 shows an enlarged view of the first center block 36 as an example of the pentagonal block 45. As shown in FIG. 5, in the case of the pentagonal block 45, it is desirable that the tip 49 of the convex portion 48 provided in any one of the tire axial directions is formed in the small block piece 51. In the present embodiment, the tip 49 of the convex portion 48 is formed in a small block piece 51 located at the center of the block in the tire circumferential direction.

  The angle θ1 with respect to the tire circumferential direction of the edge 54 forming the convex portion 48 of the pentagonal block 45 or the hexagonal block 46 is preferably 5 ° or more, more preferably 7 ° or more, and preferably 15 ° or less. Preferably it is 13 degrees or less. Such a convex part 48 exhibits an edge effect with a good balance in the tire circumferential direction and the tire axial direction.

  As shown in FIG. 4, the block 12 preferably includes three or more small block pieces 51, for example. The block 12 of the present embodiment includes, for example, a first small block piece 56 that forms the maximum width of the block 12 in the tire axial direction, and a pair of second blocks provided on both sides of the first small block piece 56 in the tire circumferential direction. A small block piece 57 is included. Moreover, the block 12 of the present embodiment includes, for example, a pair of first large block pieces 58 between the first small block pieces 56 and the second small block pieces 57, the second small block pieces 57, and the lateral grooves 11. And a pair of second large block pieces 59 therebetween. Thereby, since each small block piece 51 is pinched | interposed into the large block piece 52 of the both sides of a tire circumferential direction, the deformation | transformation of a tire circumferential direction is further suppressed. Accordingly, each small block piece 51 can scratch the road surface with a greater force.

  The ratio L1 / L2 between the width L1 of the large block piece 52 in the tire circumferential direction and the width L2 of the small block piece 51 in the tire circumferential direction is preferably 3.0 or more, more preferably 3.5 or more, preferably Is 5.0 or less, more preferably 4.5 or less. As a result, the performance on ice and the wear resistance are improved in a well-balanced manner.

  As shown in FIG. 1, as a heavy duty pneumatic tire for winter of this embodiment, the land ratio Lr of the tread portion 2 is preferably 68% or more, more preferably 70% or more, and preferably 78%. Below, more preferably 75% or less. Thereby, performance on ice and abrasion resistance are compatible. In the present specification, the “land ratio” is a ratio Sb / Sa of the actual total ground contact area Sb to the total area Sa of the virtual ground contact surface where all the grooves and sipes are filled between the tread ground contact Te and Te. is there.

  Each block 12 is spaced apart in the tire circumferential direction to form a block row. The number of blocks N for one round of the tire in each block row is preferably 45 or more, more preferably 50 or more, preferably 65 or less, more preferably 60 or less. Thereby, the outstanding edge effect is acquired, maintaining the rigidity of each block 12. FIG.

  The rubber hardness Ht of the tread rubber forming the tread portion 2 is preferably 60 ° or more, more preferably 63 ° or more, preferably 70 ° or less, more preferably 67 ° or less. Such a tread rubber achieves both on-ice performance and wear resistance. In the present specification, the “rubber hardness” is hardness according to durometer type A in an environment of 23 ° C. in accordance with JIS-K6253.

  The total center edge component amount ΣCE, which is the sum of the edge component amounts of sipes provided in the center region 5, is preferably 30000 mm or more, more preferably 33000 mm or more, preferably 40000 mm or less, more preferably 37000 mm or less. Thereby, the outstanding on-ice performance is exhibited while the uneven wear of the center region 5 is suppressed. The sipe edge component amount means the sum of the lengths of the edges on both sides of the sipe.

  The total shoulder edge component amount ΣSE, which is the sum of the edge component amounts of sipes provided in the shoulder regions 7 on both sides, is preferably 30000 mm or more, more preferably 33000 mm or more, preferably 40000 mm or less, more preferably 37000 mm or less. is there. Thereby, the outstanding on-ice performance is exhibited while the uneven wear of the shoulder region 7 is suppressed.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to illustrated embodiment, It can deform | transform and implement in a various aspect.

A heavy-duty pneumatic tire of size 11R22.5 having the basic pattern of FIG. As Comparative Example 1, as shown in FIG. 6, a tire in which the width in the tire circumferential direction of each block piece is equal (small block pieces and large block pieces are not divided) was prototyped. Each test tire was tested for performance on ice, performance on snow, and wear resistance. The common specifications and test methods for each test tire are as follows.
Wearing rim: 8.25 × 22.5
Tire internal pressure: 900kPa
Test vehicle: 10 ton truck, standard load 5 ton in the center of the loading platform Tire mounting position: all wheels

<Performance on ice>
The driving performance on ice of a test vehicle equipped with each test tire was evaluated based on the driver's sensuality. A result is a score which sets the comparative example 1 to 100, and shows that the performance on ice is excellent, so that a numerical value is large.

<Snow performance>
The driving performance on the snow of the test vehicle equipped with each test tire was evaluated by the driver's sensuality. A result is a score which sets comparative example 1 to 100, and shows that performance on snow is excellent, so that a numerical value is large.

<Abrasion resistance>
The amount of wear of the first center block after traveling a certain distance on the dry road surface was measured. The result is the reciprocal of the amount of wear and is represented by an index with the value of Comparative Example 1 being 100. It shows that abrasion resistance is excellent, so that a numerical value is large.
The test results are shown in Table 1.

  As can be seen from Table 1, it was confirmed that the pneumatic tires of the Examples achieved a good balance between on-ice performance and wear resistance.

2 tread portion 3 center main groove 5 center region 7 shoulder region 10 narrow groove 11 lateral groove 12 block 50 sipe 51 small block piece 52 large block piece

Claims (8)

A pair of center main grooves extending in a zigzag manner continuously in the tire circumferential direction on both sides of the tire equator on the tread portion, a center region between the pair of center main grooves, and an outer side in the tire axial direction of each center main groove A pneumatic tire having a shoulder region of
In the center region and each shoulder region, there are a plurality of blocks divided by narrow grooves extending continuously in the tire circumferential direction and having a groove width smaller than the center main groove, and lateral grooves extending in the tire axial direction. Provided,
At least one of the blocks is divided by a plurality of sipes so as to include a small block piece and a large block piece having a larger width in the tire circumferential direction than the small block piece,
Among the blocks, the small block pieces and the large block pieces are alternately arranged in the tire circumferential direction,
The narrow groove includes a center narrow groove provided between the pair of center main grooves, and a shoulder narrow groove provided outside the center main groove in the tire axial direction ,
The center narrow groove, seen including a first center narrow groove extending on the tire equator in a straight line,
The shoulder narrow groove includes a first shoulder narrow groove extending in a zigzag shape, and a second shoulder narrow groove extending linearly outward in the tire axial direction of the first shoulder narrow groove,
The block includes a second shoulder block divided by the first shoulder narrow groove, the second shoulder narrow groove, and the lateral groove,
The pneumatic tire characterized in that the second shoulder block is a pentagonal block having a convex portion protruding in the tire axial direction .   The pneumatic tire according to claim 1, wherein the block includes three or more small block pieces.   The pneumatic tire according to claim 1, wherein the block has a pentagonal or hexagonal tread whose length in the tire circumferential direction is larger than a width in the tire axial direction. The block includes a hexagonal block having a hexagonal tread surface;
The hexagonal block has a pair of convex portions protruding on both sides in the tire axial direction,
The pneumatic tire according to any one of claims 1 to 3, wherein each tip of the pair of convex portions is formed in the same small block piece.   The pneumatic tire according to any one of claims 1 to 4, wherein a groove width of the lateral groove is larger than a groove width of the center main groove.   The pneumatic tire according to any one of claims 1 to 5, wherein the center narrow groove includes a second center narrow groove extending zigzag on both outer sides of the first center narrow groove. The block includes a center block provided in the center region, and a shoulder block provided in the shoulder region,
The pneumatic tire according to claim 1, wherein the shoulder block includes a first shoulder block having a width in the tire axial direction larger than that of the center block . The ratio L1 / L2 between the width L1 in the tire circumferential direction of the large block piece and the width L2 in the tire circumferential direction of the small block piece is 3.0 to 5.0. The described pneumatic tire.

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