JP2015223966A - Tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that can improve abrasion resistance performance while maintaining on-ice performance.SOLUTION: A pneumatic tire 1 has middle blocks 11 partitioned between middle lateral grooves 12 by providing a pair of center main grooves 3, a pair of shoulder main grooves 4, a plurality of center lateral grooves 32 and the plurality of middle lateral grooves 12 in a tread part 2. In the middle blocks 11 are provided slots 15, which oppose to the center lateral grooves 3, toward which edges of the middle blocks 11 are recessed. The slots 15 have plane-shape slope surfaces 16 that incline inward in a tire radial direction, from step faces of the middle blocks 11 toward the center main grooves 3.

Description

  The present invention relates to a pneumatic tire having good wet performance and wear resistance.

  Patent Document 1 below proposes a pneumatic tire in which the dimensions of the blocks arranged in the tread portion are limited to a certain range. In this pneumatic tire, the ground pressure of each block and the slip amount with respect to the road surface are made uniform, so that an effect of obtaining good wear resistance of the block is expected.

  In the pneumatic tire, in order to improve the traction performance on a wet road surface and a shallow snow road, a narrow groove that completely crosses the block is provided at an intermediate position in the tire circumferential direction of the block. However, such a narrow groove reduces the rigidity of the block, and there is room for further improvement in improving wear resistance.

JP 2004-224131 A

  The present invention has been devised in view of the above circumstances, and its main object is to provide a pneumatic tire having good wet performance and wear resistance on the basis of providing a slot in a middle block. It is said.

  The present invention includes a pair of center main grooves extending continuously in the tire circumferential direction on both sides of the tire equator on the tread portion, and a pair of shoulders extending continuously in the tire circumferential direction on the outer side in the tire axial direction of each center main groove. A tire circumferential direction is provided by providing a main groove, a plurality of center lateral grooves communicating between the pair of center main grooves, and a plurality of middle lateral grooves communicating between the center main groove and the shoulder main grooves. A pneumatic tire having a middle block partitioned between the middle lateral grooves adjacent to each other, wherein the middle block is provided with a slot facing the center lateral groove and having a recessed edge of the middle block. The slot has a flat slope surface inclined inward in the tire radial direction from the tread surface of the middle block to the center main groove. It is characterized in.

  In the pneumatic tire of the present invention, it is desirable that the maximum depth d1 of the slot in the tire radial direction is larger than the width W1 of the slot in the tire axial direction.

  In the pneumatic tire of the present invention, it is desirable that a length L1 of the slot in the tire circumferential direction is larger than a width W1 of the slot in the tire axial direction.

  In the pneumatic tire of the present invention, it is preferable that the center main groove and the shoulder main groove extend in a zigzag shape in the tire circumferential direction.

  In the pneumatic tire according to the present invention, the center main groove and the shoulder main groove are each a long side portion inclined with respect to the tire circumferential direction, and inclined in a direction opposite to the long side portion and from the long side portion. It is desirable that short side portions having a small length in the tire circumferential direction are alternately provided in the tire circumferential direction.

  In the pneumatic tire of the present invention, it is preferable that the center lateral groove communicates with a central portion in the tire circumferential direction of the long side portion of each center main groove.

  In the pneumatic tire of the present invention, the middle lateral groove includes an intersection between the long side portion and the short side portion of the center main groove, and the long side portion and the short side portion of the shoulder main groove. It is desirable to communicate with the intersection between them.

  In the pneumatic tire of the present invention, it is preferable that the center lateral groove and the middle lateral groove are inclined in opposite directions with respect to the tire axial direction.

  The pneumatic tire of the present invention has a pair of center main grooves extending continuously in the tire circumferential direction on both sides of the tire equator in the tread portion, and the tire axial direction outer side of each center main groove continuously in the tire circumferential direction. By providing a pair of extending shoulder main grooves, a plurality of center lateral grooves communicating between the pair of center main grooves, and a plurality of middle lateral grooves communicating between the center main groove and the shoulder main grooves, Middle blocks divided between the middle lateral grooves adjacent to each other in the tire circumferential direction are provided.

  The middle block is provided with a slot facing the center lateral groove and having a concave end edge of the middle block. The slot has a flat slope surface inclined inward in the tire radial direction from the tread surface of the middle block toward the center main groove.

  The middle block provided with such a slot has higher rigidity than the block provided with a narrow groove that completely crosses the middle block. For this reason, the wear resistance of the block is enhanced. In addition, since the slot has the slope surface, the rigidity in the vicinity of the slot of the middle block changes smoothly from the center side of the block toward the center main groove side. Therefore, such a middle block can exhibit superior uneven wear resistance as compared with the block provided with the narrow groove and the lug groove.

  Moreover, the slot smoothly guides the water film between the tread surface of the middle block and the road surface into the center main groove during wet traveling. Since the slot faces the center lateral groove, the water guided from the slot into the center main groove is effectively discharged outside the tire together with the water in the center lateral groove. Accordingly, the pneumatic tire of the present invention can obtain good wet performance.

  As described above, the pneumatic tire of the present invention can improve wear resistance without sacrificing wet performance.

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 middle land part of FIG. FIG. 4 is an enlarged perspective view of the middle block of FIG. 3. (A) is BB sectional drawing of the middle block of FIG. 4, (b) is an enlarged plan view of the tread of the middle block of FIG. It is an enlarged view of the center land part of FIG. It is an enlarged view of the shoulder land part of FIG. 3 is a development view of a tread portion of Comparative Example 1. FIG. 6 is a development view of a tread portion of Comparative Example 2. FIG.

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 (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire 1 of this embodiment is suitably used for heavy-duty vehicles such as trucks and buses, for example.

  As shown in FIG. 1, the tread portion 2 is provided with a pair of center main grooves 3 and 3 and a pair of shoulder main grooves 4 and 4.

  The center main groove 3 is provided on both sides of the tire equator C. The shoulder main groove 4 is provided on the outer side in the tire axial direction of the center main groove 3 and on the most tread grounding end Te side.

  The tread contact end Te means the contact end on the outermost side in the tire axial direction when a normal load is applied to the tire 1 in a normal state and contacted with a flat surface with a camber angle of 0 °.

  The “normal state” is an unloaded state in which a tire is assembled on a normal rim (not shown) and filled with a normal internal pressure. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in this normal state.

  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, ETRTO Then "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. “JAMATA” is the “maximum air pressure”, TRA is the table “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO.

  “Regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. “JATMA” is the “maximum load capacity”, TRA is the table “TIRE LOAD” The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” in the case of ETRTO.

  Each of the center main groove 3 and the shoulder main groove 4 extends continuously in the tire circumferential direction. The center main groove 3 and the shoulder main groove 4 of this embodiment are, for example, in a zigzag shape.

  The center main groove 3 of the present embodiment has a long side 3a that is inclined with respect to the tire circumferential direction, a short that is inclined in the opposite direction to the long side 3a and is smaller in the tire circumferential direction than the long side 3a. The side portions 3b are alternately provided in the tire circumferential direction.

  Similarly to the center main groove 3, the shoulder main groove 4 also has a long side portion 4a inclined with respect to the tire circumferential direction, and is inclined in a direction opposite to the long side portion 4a and is longer in the tire circumferential direction than the long side portion 4a. Are arranged alternately in the tire circumferential direction.

  The groove width W3 of the center main groove 3 and the groove width W4 of the shoulder main groove 4 are preferably 1.5% to 5% of the tread ground contact width TW, for example. When the groove widths W3 and W4 are less than 1.5% of the tread contact width TW, the drainage of the tread portion 2 may be deteriorated. When the groove widths W3 and W4 exceed 5% of the tread ground contact width TW, the rubber volume is insufficient and the wear resistance may be reduced.

  The tread contact width TW is a distance in the tire axial direction between the tread contact ends Te and Te in the normal state.

  FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2, the groove depth d3 of the center main groove 3 and the groove depth d4 of the shoulder main groove 4 are preferably 10 mm to 20 mm, for example. Such center main groove 3 and shoulder main groove 4 improve wear resistance and wet performance in a well-balanced manner.

  As shown in FIG. 1, the tread portion 2 has a plurality of center lateral grooves 32 that communicate between the pair of center main grooves 3 and 3, and a plurality that communicates between the center main groove 3 and the shoulder main grooves 4. Middle lateral grooves 12 are provided.

  The center lateral groove 32 communicates, for example, between the long side portions 3 a and 3 a of the center main groove 3. In a preferred embodiment, the center lateral groove 32 communicates with, for example, the central portion of the long side portion 3a in the tire circumferential direction. The center lateral groove 32 of the present embodiment communicates with the long side portion 3a substantially perpendicularly. For example, the center lateral groove 32 is inclined at an angle θ1 of 5 to 15 ° with respect to the tire axial direction.

  The groove width W5 of the center lateral groove 32 is, for example, 5.0 to 10.0 mm. Such center lateral grooves 32 enhance wet performance while maintaining wear resistance.

  The middle lateral groove 12 communicates with the intersection between the long side 3a and the short side 3b of the center main groove 3 and the intersection between the long side 4a and the short side 4b of the shoulder main groove 4. ing. For example, the middle lateral groove 12 is inclined in the direction opposite to the center lateral groove 32 with respect to the tire axial direction.

  An angle θ2 of the middle lateral groove 12 with respect to the tire axial direction is, for example, 5 to 15 °. The groove width W6 of the middle lateral groove 12 is, for example, 5.0 to 10.0 mm.

  By providing the center main groove 3, the shoulder main groove 4, the center lateral groove 32, and the middle lateral groove 12, the middle block 11 is provided between the center main groove 3 and the shoulder main groove 4 in the tread portion 2. A plurality of middle land portions 10 provided in the tire circumferential direction, a center land portion 30 provided with a plurality of center blocks 31 in the tire circumferential direction between the pair of center main grooves 3 and 3, and a tire axial direction of the shoulder main groove 4 The outer shoulder land portion 40 is divided.

  FIG. 3 shows an enlarged view of the middle land portion 10. As shown in FIG. 3, the middle land portion 10 is a block row in which middle blocks 11 divided by a plurality of middle lateral grooves 12 are arranged in the tire circumferential direction.

  The middle block 11 has, for example, a substantially parallelogram-shaped tread surface 11s.

  The middle block 11 is provided with a slot 15 that faces the center lateral groove 32 and in which the edge 11e of the middle block 11 is recessed.

  That the slot 15 faces the center lateral groove 32 includes that at least a part of the slot 15 is provided in the projection region of the center lateral groove 32 in the tire axial direction.

  FIG. 4 shows an enlarged perspective view of the middle block 11. As shown in FIG. 4, the slot 15 has a planar shape inclined inward in the tire radial direction from the tread surface 11 s of the middle block 11 toward the center main groove 3 (shown in FIG. 3, the same applies hereinafter). A slope surface 16 is provided.

  The slope surface 16 has, for example, a substantially trapezoidal shape in which the first ridge line 17a on the tread surface 11s of the middle block 11 and the second ridge line 17b on the side wall surface 9 of the middle block 11 extend in parallel to each other.

  The middle block 11 provided with such a slot 15 has greater rigidity than a block provided with a narrow groove that completely crosses the block. For this reason, the wear resistance of the block is enhanced. Moreover, since the slot 15 has the slope surface 16, the rigidity of the middle block 11 in the vicinity of the slot 15 smoothly changes from the center of the block toward the center main groove. Therefore, such a middle block 11 can exhibit excellent uneven wear resistance as compared with the block provided with the narrow groove and the lug groove.

  Moreover, the slot 15 smoothly guides the water film between the tread surface 11s of the middle block 11 and the road surface into the center main groove during wet traveling. Since the slot 15 is opposed to the center lateral groove (shown in FIG. 1, the same applies hereinafter), the water introduced from the slot 15 into the center main groove is effective together with the water in the center lateral groove 32. Is discharged outside the tire. Accordingly, the pneumatic tire of the present invention can obtain good wet performance.

  FIG. 5A shows a BB cross-sectional view of FIG. As shown in FIG. 5A, in order to further exert the above-described effect, the angle θ3 of the slope surface 16 with respect to the tread surface is preferably 45 ° or more, more preferably 50 ° or more, and preferably 65 °. Below, more preferably 60 ° or less.

  FIG. 5B shows an enlarged plan view of the tread surface 11s of the middle block 11 of FIG. As shown in FIG. 5 (b), the opening edge 20 of the slot 15 on the tread surface 11s has a first edge 21 extending in the tire circumferential direction and both ends 21t of the first edge 21 toward the outside of the block. A pair of extending second edges 22 is included. The pair of second edges 22 and 22 are inclined in directions opposite to each other. As a result, the width of the opening edge 20 in the tire circumferential direction gradually increases toward the outside of the block. Such a slot 15 effectively guides the water pushed away by the tread of the middle block 11 to the center main groove during wet running.

  As shown in FIG. 4, the slot 15 includes, for example, a pair of left and right slot side surfaces 19 extending from the second edge 22 to the bottom 15 d of the slot 15 between the slope surface 16 and the side wall surface 9 of the middle block 11. Yes. The slot side surface 19 is formed by a substantially triangular plane, for example.

  As shown in FIG. 5B, the length L1 of the slot 15 in the tire circumferential direction is preferably 0.08 times or more, more preferably, the maximum length L6 of the middle block 11 in the tire circumferential direction. It is 0.1 times or more, preferably 0.16 times or less, more preferably 0.14 times or less. Such a slot 15 maintains the rigidity of the middle block 11 in the tire circumferential direction and improves the wear resistance.

  From the same viewpoint, the length L1 of the slot 15 is desirably larger than the width W1 of the slot 15 in the tire axial direction. The ratio W1 / L1 between the length L1 and the width W1 of the slot 15 is preferably 0.65 or more, more preferably 0.68 or more, preferably 0.75 or less, more preferably 0.72. It is as follows.

  The width W1 of the slot 15 is preferably 0.08 times or more, more preferably 0.11 times or more, preferably 0.17 times or less, more preferably 0, of the width W7 of the middle block 11 in the tire axial direction. .14 times or less. Such a slot 15 exhibits excellent handling stability while improving wet performance and wear resistance.

  As shown in FIG. 5A, the maximum depth d1 of the slot 15 in the tire radial direction is desirably larger than the width W1 of the slot 15 (shown in FIG. 5B). The maximum depth d1 in the tire radial direction of the slot 15 is preferably 0.45 times or more, more preferably 0.48 times or more, preferably 0.55 times or less of the groove depth d3 of the center main groove 3. More preferably, it is 0.52 times or less. Such a slot 15 improves wet performance and wear resistance in a well-balanced manner.

  As shown in FIG. 1, in the present embodiment, the slots 15 and 15 provided on both sides of the center lateral groove 32 are displaced from each other in the tire circumferential direction. Such a slot 15 effectively suppresses uneven wear of the middle block 11.

  FIG. 6 shows an enlarged view of the center land portion 30. As shown in FIG. 6, the center land portion 30 is a block row in which center blocks 31 divided by a plurality of center lateral grooves 32 are arranged in the tire circumferential direction.

  The center block 31 includes a first portion 36 provided between the short side portions 3b and 3b of the pair of center main grooves 3, and a second portion 37 disposed on one side of the first portion 36 in the tire circumferential direction. , And a third portion 38 disposed on the other side of the first portion 36 in the tire circumferential direction.

  The first portion 36 has, for example, a substantially parallelogram-shaped tread surface 36s.

  The second portion 37 and the third portion 38 have substantially trapezoidal treads 37s and 38s, respectively. The tread surface 37s of the second portion 37 and the tread surface 38s of the third portion 38 have substantially the same shape. The second portion 37 and the third portion 38 are provided so as to be displaced from each other in the tire axial direction. Such a center block 31 improves the traction performance on wet road surfaces and light snow roads.

  The maximum width W8 of the center block 31 in the tire axial direction is, for example, 0.15 to 0.25 times the tread contact width TW (shown in FIG. 1 and the same applies hereinafter). Such a center block 31 exhibits excellent wear resistance while maintaining wet performance.

  FIG. 7 shows an enlarged view of the shoulder land portion 40. As shown in FIG. 7, the shoulder land portion 40 is a block row in which shoulder blocks 41 divided by a plurality of shoulder lateral grooves 42 are arranged in the tire circumferential direction.

  The shoulder lateral groove 42 extends, for example, from the shoulder main groove 4 to the tread grounding end Te. For example, the shoulder lateral grooves 42 are inclined in the same direction as the middle lateral grooves 12 (shown in FIG. 1) with respect to the tire axial direction. An angle θ5 of the shoulder lateral groove 42 with respect to the tire axial direction is, for example, 5 to 15 °. The width W11 of the shoulder lateral groove 42 is, for example, 8 to 12 mm.

  As shown in FIG. 2, the groove depth d7 of the shoulder lateral groove 42 is, for example, 0.15 to 0.20 times the groove depth d3 of the shoulder main groove 4. Such a shoulder lateral groove 42 increases the rigidity of the shoulder land portion 40 and exhibits excellent steering stability.

  As shown in FIG. 7, the shoulder block 41 includes, for example, a first shoulder block piece 45 and a second shoulder block piece 46 which are divided by a shoulder sipe 44 extending linearly from the shoulder main groove 4 to the tread grounding end Te. Is included. In this specification, “sipe” means a cut having a width of 1.0 mm or less, and is distinguished from a drainage groove.

  The first shoulder block piece 45 has a substantially trapezoidal tread surface 45s. The width W9 of the first shoulder block piece 45 in the tire axial direction is, for example, 0.12 to 0.18 times the tread contact width TW (shown in FIG. 1).

  The second shoulder block piece 46 has a substantially pentagonal tread surface 46s having an inner edge 47 that protrudes inward in the tire axial direction. The width W10 of the second shoulder block piece 46 in the tire axial direction is larger than the width W9 of the first shoulder block piece 45. Such a second shoulder block piece 46 increases the rigidity of the shoulder block 41 in the tire axial direction and improves steering stability.

  In order to further exert the above-described effects, the ratio W9 / W10 between the width W9 of the first shoulder block piece 45 and the width W10 of the second shoulder block piece 46 is preferably 0.85 or more, more preferably 0. .87 or more, preferably 0.95 or less, more preferably 0.93 or less.

  For example, the shoulder sipe 44 is inclined in the same direction as the shoulder lateral groove 42 with respect to the tire axial direction. An angle θ6 of the shoulder sipe 44 with respect to the tire axial direction is, for example, 5 to 15 °. Such a shoulder sipe 44 makes the contact pressure acting on the shoulder block 41 uniform and suppresses uneven wear.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, this invention is not limited to embodiment of illustration, It can implement by changing into a various aspect.

A heavy-duty tire of size 215 / 75R17.5 having the basic structure shown in FIG. As Comparative Example 1, as shown in FIG. 8, a tire in which a middle narrow groove that completely crosses the block was provided in a middle block was manufactured as a prototype. As Comparative Example 2, as shown in FIG. 9, a tire in which a slot was not provided in the middle block was manufactured as a trial. Each test tire was tested for wet performance and wear resistance. The common specifications and test methods for each test tire are as follows.
Wearing rim: 6.0 × 17.5
Tire internal pressure: 700kPa
Tire mounting position: Rear wheel (drive wheel)
Test vehicle: 4t truck, 50% of the standard load capacity is loaded in front of the loading platform

<Abrasion resistance>
With the test vehicle, the remaining groove depth of the center main groove was measured when traveling on a general road for a certain distance. A result is displayed by the index | exponent which sets the comparative example 1 to 100, and shows that abrasion resistance is excellent, so that a numerical value is large.

<Wet performance>
With the test vehicle, the passage time when passing a test course with a total length of 10 m under the following conditions was measured. The evaluation is the reciprocal of the passage time, and is represented by an index with the value of Comparative Example 1 being 100. The larger the value, the shorter the passage time and the better the wet performance.
Road surface: Asphalt with a 5mm thick water film Start method: 2nd speed-1500rpm fixed, start with clutch connected.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the tires of the examples had good wet performance and wear resistance.

2 Tread part 3 Center main groove 4 Shoulder main groove 11 Middle block 12 Middle horizontal groove 15 Slot 16 Slope surface 32 Center horizontal groove

The present invention includes a pair of center main grooves extending continuously in the tire circumferential direction on both sides of the tire equator on the tread portion, and a pair of shoulders extending continuously in the tire circumferential direction on the outer side in the tire axial direction of each center main groove. A tire circumferential direction is provided by providing a main groove, a plurality of center lateral grooves communicating between the pair of center main grooves, and a plurality of middle lateral grooves communicating between the center main groove and the shoulder main grooves. A pneumatic tire having a middle block divided between the middle lateral grooves adjacent to each other, wherein the middle block is provided with a slot facing the center lateral groove and having a recessed edge of the middle block. the slots have a flat slope surface from tread inclined radially inward tire to the center main groove of the middle block, wherein the scan Tsu City of tire maximum radial depth d1 is characterized in that the at center main groove of the groove depth of 0.45 times or more.

In the pneumatic tire of the present invention, it is preferable that the center lateral groove communicates with the long side portion of each center main groove.

Claims (8)

A pair of center main grooves extending continuously in the tire circumferential direction on both sides of the tire equator on the tread portion, and a pair of shoulder main grooves extending continuously in the tire circumferential direction on the outer side in the tire axial direction of each center main groove, By providing a plurality of center lateral grooves communicating between the pair of center main grooves and a plurality of middle lateral grooves communicating between the center main grooves and the shoulder main grooves, they are adjacent to each other in the tire circumferential direction. A pneumatic tire having a middle block divided between the middle lateral grooves,
The middle block is provided with a slot that is opposed to the center lateral groove and in which an edge of the middle block is recessed,
The pneumatic tire according to claim 1, wherein the slot has a flat slope surface inclined inward in the tire radial direction from the tread surface of the middle block to the center main groove.   The pneumatic tire according to claim 1, wherein a maximum depth d1 of the slot in the tire radial direction is larger than a width W1 of the slot in the tire axial direction.   The pneumatic tire according to claim 1 or 2, wherein a length L1 of the slot in the tire circumferential direction is larger than a width W1 of the slot in the tire axial direction.   The pneumatic tire according to claim 1, wherein the center main groove and the shoulder main groove extend in a zigzag shape in the tire circumferential direction.   The center main groove and the shoulder main groove each have a long side portion that is inclined with respect to the tire circumferential direction, an inclination opposite to the long side portion, and a length in the tire circumferential direction that is longer than the long side portion. The pneumatic tire according to claim 4, wherein small short sides are alternately provided in the tire circumferential direction.   The pneumatic tire according to claim 5, wherein the center lateral groove communicates with a center portion in a tire circumferential direction of the long side portion of each center main groove.   The middle lateral groove communicates with an intersecting portion between the long side portion and the short side portion of the center main groove and an intersecting portion between the long side portion and the short side portion of the shoulder main groove. The pneumatic tire according to claim 5 or 6. The pneumatic tire according to any one of claims 1 to 7, wherein the center lateral groove and the middle lateral groove are inclined in directions opposite to each other with respect to a tire axial direction.

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