JP6360587B2 - Heavy duty pneumatic tire - Google Patents

Description

  The present invention relates to a heavy-duty pneumatic tire that achieves both wet performance and performance on snow.

  For example, Patent Document 1 below proposes a heavy duty pneumatic tire in which a plurality of blocks are formed in a tread portion. Each block is divided into three parts, a pair of outer pieces and a central piece between them, by two divided sipes crossing the blocks in the tire axial direction. Such three block pieces increase the frictional force on hard snow roads or ice because each edge scratches the road surface.

  The outer piece of the block of Patent Document 1 has a protrusion protruding in a step shape in the tire axial direction from the center piece. Such protrusions are useful for increasing the snow column shear force in the longitudinal grooves when traveling on snow.

  However, in the block of Patent Document 1, the protrusions of the pair of outer pieces are provided on the same longitudinal groove side, and the protrusions are arranged close to each other in the tire circumferential direction. The blocks provided with such protrusions tend to clog the vertical grooves because they retain snow between the protrusions when running on snow. Moreover, the protrusions that are close to each other locally reduce the groove volume of the longitudinal groove, which may reduce the wet performance.

JP 2005-280457 A

  The present invention has been devised in view of the actual situation as described above, and mainly provides a heavy-duty pneumatic tire that achieves both wet performance and on-snow performance on the basis of improving the shape of the block. It is aimed.

  The present invention is a heavy duty pneumatic tire having a plurality of blocks divided in a tread portion by a plurality of vertical grooves extending in the tire circumferential direction and a plurality of horizontal grooves extending in the tire axial direction, wherein at least one of the blocks The first outer piece is divided into three parts, a first outer piece, a second outer piece, and a central piece between them, by a split sipe composed of only two crossing the block in the tire axial direction. Has a first protrusion protruding in a step shape on one side in the tire axial direction from the central piece, and the second outer piece protrudes in a step shape on the other side in the tire axial direction from the central piece. It has the 2nd protrusion part which was made.

  In the tread plan view of the heavy duty pneumatic tire of the present invention, the center piece has edges on both sides facing the longitudinal groove inclined in the same direction, and the edge facing the longitudinal groove of the first protrusion It is desirable that the edge of the second protrusion facing the vertical groove is inclined in the same direction as the edge of the central piece.

  In the heavy duty pneumatic tire of the present invention, the first protrusion protrudes from an extension line of the edge of the central piece, and the maximum protrusion amount is 0.10 to 0 of the width of the block in the tire axial direction. .25 times, and the second protrusion protrudes from the extended line of the edge of the central piece, and the maximum protrusion amount is 0.10 to 0.25 times the width of the block in the tire axial direction. It is desirable.

  In the heavy-duty pneumatic tire of the present invention, the block includes a first block in which a maximum protrusion amount of the first protrusion and a maximum protrusion amount of the second protrusion are the same, and the first protrusion It is desirable to include a second block having a maximum protrusion amount different from the maximum protrusion amount of the second protrusion.

  In the heavy duty pneumatic tire of the present invention, it is desirable that the first blocks and the second blocks are alternately arranged in the tire circumferential direction.

  In the heavy-duty pneumatic tire of the present invention, the first blocks and the second blocks are alternately arranged in the tire circumferential direction, and only the first blocks are arranged in the tire circumferential direction. It is desirable that adjacent block rows are adjacent in the tire axial direction.

  In the heavy-duty pneumatic tire of the present invention, the first outer piece has a first non-projecting portion on the opposite side of the first protruding portion that does not protrude outward from the center piece, and the second outer piece. It is desirable to have a second non-projecting part that does not protrude outward from the central piece on the opposite side of the second projecting part.

  In the tread plan view of the heavy-duty pneumatic tire of the present invention, the center piece is inclined in the same direction on both sides facing the vertical groove, and faces the vertical groove of the first non-projection. It is desirable that the edge and the edge of the second non-projecting part facing the vertical groove are inclined in the opposite direction to the edge of the central piece.

  The heavy duty pneumatic tire of the present invention has a plurality of blocks in the tread portion that are partitioned by a plurality of vertical grooves extending in the tire circumferential direction and a plurality of horizontal grooves extending in the tire axial direction.

  At least one of the blocks is divided into three parts, a first outer piece, a second outer piece, and a central piece between them, by a split sipe composed of only two that cross the block in the tire axial direction.

  The first outer piece has a first protrusion protruding in a step shape on one side in the tire axial direction from the center piece. The second outer piece has a second protrusion protruding in a step shape on the other side in the tire axial direction from the center piece. Such step-like first protrusions and second protrusions are useful for obtaining large traction by strongly pressing and shearing the snow in the longitudinal groove when traveling on snow.

  Since the first protrusion and the second protrusion are provided on the opposite sides in the tire axial direction, snow clogging between them does not occur, so that the protrusions approach each other and are aligned in the tire circumferential direction. Compared with the case where it is, the performance on snow is excellent.

  Moreover, since the first protrusion and the second protrusion are not concentrated in one vertical groove, the groove volume of the vertical groove is not greatly reduced locally, and excellent wet performance is obtained. .

  As described above, the pneumatic tire of the present invention can balance wet performance and performance on snow with good balance.

It is an expanded view of the tread part of the pneumatic tire of this embodiment. It is an enlarged view of the center land part of FIG. It is an enlarged view of the center block of FIG. FIG. 4 is a cross-sectional view taken along line AA of the divided sipe of FIG. 3. It is an enlarged view of the middle land part of FIG. It is an enlarged view of the inner side shoulder land part and outer side shoulder land part of FIG. It is an expanded view of the tread part of a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a heavy duty pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The tire 1 of the present embodiment is, for example, a winter tire, and the tread portion 2 is divided into a plurality of vertical grooves 3 extending in the tire circumferential direction and a plurality of horizontal grooves 7 extending in the tire axial direction. A plurality of blocks 8 are formed.

  The longitudinal groove 3 of the present embodiment includes, for example, a center main groove 4, a shoulder main groove 5, and a shoulder sub groove 6.

  The center main groove 4 is provided, for example, on the tire equator C side most. A pair of center main grooves 4 are provided on both sides of the tire equator C, for example. The center main groove 4 extends continuously in the tire circumferential direction.

  The shoulder main groove 5 is provided, for example, on the outer side in the tire axial direction of each center main groove 4. The shoulder main groove 5 extends continuously in the tire circumferential direction.

  The groove width W1 of the center main groove 4 and the groove width W2 of the shoulder main groove 5 are, for example, 3.0 to 8.0% of the tread ground contact width TW. The groove depth of the center main groove 4 and the shoulder main groove 5 is preferably 10 to 25 mm, for example.

  The tread contact width TW is a distance in the tire axial direction between the tread contact ends Te and Te of a normal tire 1 that is assembled to a normal rim (not shown) and filled with a normal internal pressure and is unloaded. is there.

  The “regular rim” is a rim defined 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".

  “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. The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  The “tread contact end Te” is a contact position on the outermost side in the tire axial direction when the normal tire 1 is loaded with a normal load and contacted with a flat surface with a camber angle of 0 °.

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

  The shoulder sub-groove 6 extends, for example, continuously in the tire circumferential direction on the tread ground contact Te side. The shoulder minor groove 6 is linear, for example.

  The shoulder sub-groove 6 has a groove width W3 that is smaller than the center main groove 4 and the shoulder main groove 5, for example. The groove width W3 of the shoulder sub-groove 6 is, for example, 0.10 to 0.15 times the groove width W2 of the shoulder main groove 5. Similarly, the shoulder sub-groove 6 has a groove depth smaller than that of the center main groove 4 and the shoulder main groove 5. The groove depth of the shoulder sub-groove 6 is preferably 5 to 13 mm, for example.

  The tread portion 2 is divided into a center land portion 10, a middle land portion 11, an inner shoulder land portion 12, and an outer shoulder land portion 13 by a center main groove 4, a shoulder main groove 5, and a shoulder sub groove 6. Yes.

  FIG. 2 shows an enlarged view of the center land portion 10. As shown in FIG. 2, the center land portion 10 is provided between the pair of center main grooves 4 and 4. The center land portion 10 is divided into a plurality of center blocks 15 by a plurality of center lateral grooves 14.

  Each center lateral groove 14 communicates between the pair of center main grooves 4 and 4. The center lateral grooves 14 extend linearly, for example, and are inclined in the same direction.

  An angle θ1 of the center lateral groove 14 with respect to the tire axial direction is, for example, 3 to 7 °. The groove width W6 of the center lateral groove 14 is preferably 5 to 10 mm, for example.

  FIG. 3 shows an enlarged view of the center block 15. As shown in FIG. 3, the center block 15 is provided with two divided sipes 18 that cross the block in the tire axial direction.

  The split sipe 18 extends along, for example, the center lateral groove 14 (shown in FIG. 2 and the same hereinafter). For example, the divided sipes 18 of the present embodiment extend substantially parallel to each other. Each divided sipe 18 may extend at different angles with respect to the tire axial direction.

  4 shows a cross-sectional view taken along line AA of FIG. As shown in FIG. 4, the divided sipe 18 has a groove depth d1 of 5 to 10 mm, for example.

  The split sipe 18 includes, for example, a main body portion 34 extending in a tire radial direction except for the bottom portion, and an opening 35 having a step-like width increasing outside the main body portion 34 in the tire radial direction.

  The main body 34 extends in a wave shape in the tread plan view (see FIG. 3). The width W4 of the main body 34 is, for example, 0.3 to 1.0 mm. The depth d2 of the main body 34 is, for example, 4.0 to 9.5 mm.

  A width W5 of the opening 35 is, for example, 0.5 to 2.0 mm. The depth d3 of the opening 35 is, for example, 0.5 to 1.5 mm. The opening 35 of the present embodiment is formed, for example, by expanding the sipe width by the sipe walls 38 on both sides.

  The split sipe 18 having the main body 34 and the opening 35 effectively absorbs moisture on the road surface when traveling on ice, and exhibits excellent performance on ice.

  As shown in FIG. 3, the center block 15 is provided with only the above-described two divided sipes 18, so that the first outer piece 21 and the second outer piece 22 (hereinafter referred to as the two outer pieces 22) on both sides in the tire circumferential direction are provided. These are also simply referred to as “outer pieces”) and a central piece 24 between them.

  The first outer piece 21, the second outer piece 22, and the central piece 24 are formed as plain block pieces that are not provided with cuts such as sipes. Each of the outer pieces 21 and 22 and the central piece 24 as described above serves to suppress uneven wear of the block.

  The center piece 24 has, for example, a rectangular tread. As a desirable mode, central piece 24 of this embodiment has a tread of parallelogram shape as a whole, for example. Each edge 36, 36 facing the center main groove 4 of the center piece 24 is inclined in the same direction with respect to the tire axial direction and extends linearly, for example.

  The first outer piece 21 has a first protrusion 26 that protrudes in a step shape on one side in the tire axial direction from the central piece 24. On the other hand, the second outer piece 22 has a second protrusion 27 protruding in a step shape on the other side in the tire axial direction from the central piece 24. In the present specification, the first protrusion 26 and the second protrusion 27 may be simply referred to as a protrusion.

  The first protrusion 26 and the second protrusion 27 exhibit excellent on-snow performance by further pressing and solidifying the snow in the longitudinal groove and shearing the snow when running on the snow. Moreover, since the first protrusion 26 and the second protrusion 27 are provided on one side or the other side in the tire axial direction, each protrusion 25 does not concentrate on one vertical groove, and the vertical groove A reduction in groove volume can be prevented, and excellent wet performance can be obtained.

  Each of the edges 37a and 37b facing the center main groove 4 of the first protrusion 26 and the second protrusion 27 is preferably inclined in the same direction as the edge 36 of the central piece 24, for example. Such a protrusion 25 can more strongly compress the snow guided to the protrusion 25 side along the edge 36 of the central piece 24 when traveling on snow, and a larger snow column shear force can be obtained.

  The first protrusion 26 and the second protrusion 27 protrude from the extension line 32 of the edge 36 of the center piece 24. The maximum protrusion amount W7, which is the distance in the tire axial direction from the outer ends 39 of the protrusions 26 and 27 to the extension line 32, is preferably 0. of the width W10 of the center block 15 in the tire axial direction (shown in FIG. 2). It is 10 times or more, more preferably 0.15 times or more, preferably 0.25 times or less, more preferably 0.20 times or less. Such protrusions 26 and 27 balance wet performance and snow performance in a well-balanced manner.

  In the center block 15 of the present embodiment, it is desirable that the maximum protrusion amount W7 of the first protrusion 26 is the same as the maximum protrusion amount W8 of the second protrusion 27. Such a block having the first protrusion 26 and the second protrusion 27 (hereinafter sometimes referred to as the first block 41) can suppress uneven wear of the outer pieces 21 and 22.

  The first outer piece 21 has a first non-projecting portion 28 that does not protrude outward from the central piece 24 on the opposite side of the first protruding portion 26 in the tire axial direction. Similarly, the second outer piece 22 has a second non-projecting portion 29 that does not protrude outward from the central piece 24 on the opposite side of the second projecting portion 27 in the tire axial direction.

  An edge 33a facing the center main groove 4 of the first non-projecting portion 28 and an edge 33b facing the center main groove 4 of the second non-projecting portion 29 are inclined in the opposite direction to the edge 36 of the central piece 24. It is desirable. Such first non-projecting portions 28 and second non-projecting portions 29 exhibit an edge effect in multiple directions, and are useful for improving the performance on ice.

  As shown in FIG. 2, the center land portion 10 is preferably provided with a plurality of the first blocks 41 described above in the tire circumferential direction. Thereby, the single flow of a tire is suppressed and straight running stability is improved.

  As a desirable mode, as for the center land part 10, it is desirable for the projection part 25 of each outer piece 20 adjacent via the center lateral groove 14 to be provided in the mutually same side of a tire axial direction, respectively. Thus, when traveling on snow, the adjacent protrusions 25, 25 can cooperate to strongly press and harden snow, and a large shear force on snow can be obtained. In addition, since the center lateral groove 14 is arranged between the outer pieces 20 and 20, the compressed snow is not held between the outer pieces 20 and 20, and the outer side of the tire is smoothly removed from the outside of the tire. To be discharged.

  FIG. 5 shows an enlarged view of the middle land portion 11 of FIG. As shown in FIG. 5, the middle land portion 11 is provided between the center main groove 4 and the shoulder main groove 5. The middle land portion 11 is a block row in which a plurality of middle blocks 45 divided by a plurality of middle lateral grooves 44 are arranged in the tire circumferential direction.

  The middle lateral groove 44 communicates, for example, between the center main groove 4 and the shoulder main groove 5. For example, the middle lateral groove 44 is inclined in the direction opposite to the center lateral groove 14 (shown in FIG. 2) with respect to the tire axial direction. Moreover, the middle lateral groove 44 is displaced in the tire circumferential direction with respect to the center lateral groove 14.

  The middle block 45 has the same configuration as the above-described center block 15 (shown in FIG. 3). Of the components of the middle block 45, the components common to the center block 15 may be assigned the same reference numerals.

  The middle block 45 includes, for example, a first block 41 (shown in FIG. 3) in which the maximum protrusion amount W7 of the first protrusion 26 and the maximum protrusion amount W8 of the second protrusion 27 are the same, and the first protrusion 26. And the second block 42 in which the maximum protrusion amount W8 of the second protrusion 27 is different. In the middle land portion 11, the first blocks 41 and the second blocks 42 are provided alternately in the tire circumferential direction. Thereby, the amount of deformation of each block in the tire axial direction is different, and clogging of snow into the longitudinal groove is suppressed.

  As shown in FIG. 1, in the present embodiment, the first block 41 and the second block 42 are tires adjacent to the center land portion 10 that is a block row in which only the first blocks 41 are arranged in the tire circumferential direction. Middle land portions 11 provided alternately in the circumferential direction are arranged. Such an arrangement of the block rows is useful for preventing snow clogging in the center main groove 4 because the deformation amount of each block row during running is different.

  Each block of the middle land portion 11 is displaced in the tire circumferential direction with respect to each block of the center land portion 10. Such a middle land portion 11 further prevents snow clogging into the center main groove 4 and helps to improve drainage during wet running.

  As shown in FIG. 5, in the second block 42 of the present embodiment, for example, the maximum protrusion amount W7 of the first protrusion 26 is larger than the maximum protrusion amount W8 of the second protrusion 27. As a desirable mode, as for the 2nd block 42, the 1st projection 26 is provided in the tire axial direction outside, and the 2nd projection 27 is provided in the tire axial direction inside.

  Generally, the shoulder main groove 5 tends to have a lower ground pressure acting than the center main groove 4 and a smaller compressive force of snow in the groove. In this embodiment, the 1st protrusion 26 provided in the shoulder main groove 5 side has the largest protrusion amount larger than the 2nd protrusion 27 provided in the center main groove 4 side. Thus, when running on snow, the snow in the shoulder main groove 5 is effectively pressed and the center main groove 4 and the shoulder main groove 5 cooperate to generate a large snow column shear force.

  The maximum protrusion amount W7 of the first protrusion 26 of the second block 42 is preferably 1.65 times or more, more preferably 1.75 times or more of the maximum protrusion amount W8 of the second protrusion 27 of the second block 42. Yes, preferably 2.00 times or less, more preferably 1.90 times or less. Such a 2nd block 42 exhibits the above-mentioned effect, maintaining wet performance.

  FIG. 6 shows an enlarged view of the inner shoulder land portion 12 and the outer shoulder land portion 13. As shown in FIG. 6, the inner shoulder land portion 12 is provided between the shoulder main groove 5 and the shoulder sub-groove 6. The inner shoulder land portion 12 is a block row in which inner shoulder blocks 48 divided by a plurality of inner shoulder lateral grooves 47 are arranged in the tire circumferential direction.

  For example, the inner shoulder lateral groove 47 communicates between the shoulder main groove 5 and the shoulder sub-groove 6. For example, the inner shoulder lateral groove 47 is inclined in the direction opposite to the middle lateral groove 44 (shown in FIG. 5) with respect to the tire axial direction. Each inner shoulder lateral groove 47 is displaced with respect to the middle lateral groove 44 in the tire circumferential direction, for example.

  The inner shoulder block 48 is divided into three parts, for example, a pair of outer pieces 20 and 20 on both sides in the tire circumferential direction and a central piece 24 between them by providing only two divided sipes 18. ing.

  In the inner shoulder block 48, only one of the outer pieces 20, 20 has a protrusion 25 protruding in a step shape inward in the tire axial direction from the central piece 24. Such an inner shoulder block 48 strongly compresses the snow in the shoulder main groove 5 while maintaining the drainage of the shoulder main groove 5.

  The outer side shoulder land part 13 is provided in the tire axial direction outer side of the shoulder subgroove 6, for example. The outer shoulder land portion 13 is a block row in which outer shoulder blocks 50 divided by a plurality of outer shoulder lateral grooves 49 are arranged in the tire circumferential direction.

  Each outer shoulder lateral groove 49 extends, for example, along the tire axial direction. Each outer shoulder lateral groove 49 is displaced with respect to each inner shoulder lateral groove 47 in the tire circumferential direction, for example. The groove width of the outer shoulder lateral groove 49 is desirably increased gradually toward the outer side in the tire axial direction, for example. Such outer shoulder lateral grooves 49 exhibit excellent wet performance and wandering performance.

  The outer shoulder lateral groove 49 of the present embodiment includes a first outer shoulder lateral groove 51 and a second outer shoulder lateral groove 52 having a smaller groove width than the first outer shoulder lateral groove 51. For example, the first outer shoulder lateral grooves 51 and the second outer shoulder lateral grooves 52 are alternately provided in the tire circumferential direction.

  The outer shoulder block 50 is provided with, for example, a lag sipe 54 that extends inward in the tire axial direction from the edge 53 on the outer side in the tire axial direction and ends in the outer shoulder block 50. Such a lag sipe 54 exhibits excellent wandering performance while suppressing chipping of the outer shoulder block 50.

  It is desirable that the lag sipe 54 bends and terminates in the tire circumferential direction in the outer shoulder block 50, for example. As a further desirable mode, a pair of lug sipes 54 are provided on the outer shoulder block 50 of the present embodiment, and one lug sipes 54a and the other lug sipes 54b are bent in opposite directions and terminated. Such a pair of lug sipes 54a and 54b reduce the rigidity of the outer shoulder block 50 on the outer side in the tire axial direction to improve the wandering performance, and further suppress the cracking of the block starting from the inner end of the sipe. Useful.

  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. 1 was prototyped. As a comparative example, as shown in FIG. 7, a tire having a block in which each protrusion of a pair of outer pieces is provided on the same longitudinal groove side was manufactured. Each test tire was tested for snow performance and wet performance. 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: 10t truck, 50% of the standard load capacity loaded in the center of the loading platform Tire mounting position: all wheels

<Snow performance>
The driving performance on the snow of the test vehicle equipped with each test tire was evaluated by the driver's sensuality. The result is displayed with a score of 100 as a comparative example. The larger the value, the better the performance on snow.

<Wet performance>
Under the following conditions, the passing time when the test vehicle passed the test course having a total length of 10 m was measured. The results are displayed as an index with the passing time of the comparative example as 100. The smaller the value, the better.
Test vehicle: 10t truck (2-D car)
Loading state: Half-loading state in front of loading platform Test tire mounting location: All wheels Road surface: Asphalt with a 5mm thick water film Starting method: 2nd speed-1500rpm fixed with clutch connected.
The test results are shown in Table 1.

  As is clear from Table 1, it was confirmed that the heavy-duty pneumatic tires of the Examples balance wet performance and performance on snow in a well-balanced manner.

2 Tread portion 3 Vertical groove 7 Horizontal groove 8 Block 18 Divided sipe 21 First outer piece 22 Second outer piece 24 Center piece 26 First protrusion 27 Second protrusion

Claims (4)

A heavy load pneumatic tire having a plurality of blocks divided into a plurality of longitudinal grooves extending in the tire circumferential direction and a plurality of lateral grooves extending in the tire axial direction on the tread portion,
At least one of the blocks is divided into three parts, a first outer piece, a second outer piece, and a central piece between them, by a split sipe consisting of only two that cross the block in the tire axial direction.
The first outer piece has a first protrusion protruding in a step shape on one side in the tire axial direction from the center piece,
The second outer piece has a second protrusion protruding in a step shape on the other side in the tire axial direction from the central piece,
In tread plan view,
The central piece has one edge facing the longitudinal groove and the other edge,
Each of the one edge and the other edge is inclined in one direction with respect to the tire circumferential direction, and the one edge and the other edge are inclined in the same direction with respect to the tire circumferential direction. And
The edge of the first protrusion facing the vertical groove and the edge of the second protrusion facing the vertical groove are inclined in the same direction with respect to the edge of the central piece and the tire circumferential direction. A heavy-duty pneumatic tire characterized by
The block is a first block in which the maximum protrusion amount of the first protrusion and the maximum protrusion amount of the second protrusion are the same;
2. The heavy duty pneumatic tire according to claim 1, comprising a second block in which the maximum protrusion amount of the first protrusion and the maximum protrusion amount of the second protrusion are different.   The heavy-duty pneumatic tire according to claim 2, wherein the first block and the second block are alternately arranged in a tire circumferential direction. A block row in which the first blocks and the second blocks are alternately arranged in the tire circumferential direction;
The heavy duty pneumatic tire according to claim 3, wherein a block row in which only the first blocks are arranged in the tire circumferential direction is adjacent in the tire axial direction.

Images