JP2006160195A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving the anti-abrasiveness and the off-road running performance when the tire has worn. <P>SOLUTION: The tread surface 1 of this pneumatic tire is partitioned into a plurality of blocks 4 by circumferential grooves 2 extending in the tire circumferential direction T and transverse grooves 3 extending in the tire width direction. At the tread surfaces 4Ba, Xa, Ya of each block 4 are provided with shallow groove parts 7 and 10 having a width of 1-3 mm and a depth of 1-4 mm stretching in the tire width direction in such an arrangement that at least their one-side ends are positioned inside the block 4. The shallow groove parts 7 and 10 are provided with a sipe 8 extending at their bottoms 7a and 10a and given a depth d of smaller than 10 mm and an amplitude w of 1.0-2.0 mm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that improves both wear resistance and off-road performance during wear.

  Conventionally, pneumatic tires used for four-wheel drive vehicles, light trucks, etc. generally employ a block pattern with lateral grooves extending in the tire width direction to improve off-road driving performance (off-road performance) I try to secure the ingredients. Furthermore, sipes are arranged in the blocks, and the off-road performance is further improved by the edge components.

  However, the pneumatic tire described above tends to cause uneven wear due to the block pattern, and heel and toe wear tends to occur when used for a front tire. In particular, tires of a size conforming to the light truck standard such as a pickup truck have a deeper groove than a passenger car (PC) standard tire, and the load per unit area on the ground contact surface is high, and this tendency is strong.

Therefore, conventionally, as a countermeasure, a shallow groove extending in the tire width direction is formed in the block, and a sipe extending straight along the bottom of the shallow groove is formed to improve uneven wear resistance. Further, there is a technique for further improving the off-road performance (see, for example, Patent Document 1). However, since the block rigidity is lower than when a sipe is provided alone, there is a drawback that wear resistance is reduced, and when the shallow groove is worn away, the off-road performance is greatly reduced due to the reduction of edge components. There was a problem to do.
JP-A-1-132406

  An object of the present invention is to form a shallow groove extending in the tire width direction in the block and extend a sipe along the bottom of the shallow groove to improve uneven wear resistance and further improve off-road performance. An object of the present invention is to provide a pneumatic tire capable of improving the wear resistance and the off-road performance during wear.

  The pneumatic tire of the present invention that achieves the above object is provided with a plurality of circumferential grooves extending in the tire circumferential direction on the tread surface, and lateral grooves extending in the tire width direction are arranged at a predetermined pitch in the tire circumferential direction. A plurality of blocks are defined by the lateral grooves and the circumferential grooves, and a shallow groove portion having a width of 1 to 3 mm and a depth of 1 to 4 mm is formed on the tread surface of the block so that at least one end is located in the block. One sipe extending in the tire width direction and having an amplitude at the groove bottom of the shallow groove portion is extended along the direction in which the shallow groove portion extends, and the depth of the sipe is less than 10 mm. It is characterized by being 1.0 to 2.0 mm.

  According to the present invention described above, since the sipe provided at the groove bottom of the shallow groove portion is formed into a sipe having an amplitude, the opening of the sipe can be suppressed, so that the rigidity of the entire block is improved and the wear resistance is improved. Can be improved.

  Further, when the shallow groove portion disappears due to wear of the block, the sipe having the amplitude is exposed on the tread surface, so that a long edge component can be secured. For this reason, it is possible to prevent the off-road performance from greatly deteriorating at the time of wear and to exhibit higher off-road performance than before at the time of wear.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of a pneumatic tire according to the present invention, and a tread surface 1 is provided with a plurality of circumferential grooves 2 extending along a tire circumferential direction T. The plurality of circumferential grooves 2 divide a first circumferential groove 2A extending on the tire equatorial plane EP into a straight shape, a center region 1A of the tread surface 1 and shoulder regions 1B on both sides thereof. The second circumferential groove 2B, the first circumferential groove 2A, and the first circumferential groove 2A, each of which is a see-through groove (a circumferential groove that can be seen from end to end when the tread surface is developed over one circumference of the tire) A third circumferential groove 2C extending in a zigzag manner in the tire circumferential direction T is formed between the two circumferential grooves 2B. The lateral grooves 3 extending in the tire width direction are arranged at a predetermined pitch in the tire circumferential direction T, and a large number (a plurality of) blocks 4 are partitioned and formed on the tread surface 1 by the circumferential grooves 2 and the lateral grooves 3.

  The lateral grooves 3A disposed in the center region 1A are disposed at a pitch twice that of the lateral grooves 3B disposed in the shoulder region 1B, and are disposed at a longer pitch than the lateral grooves 3B. Thereby, the block 4A formed in the center region 1A is a large block having a block length larger than that of the block 4B in the shoulder region 1B. The lateral grooves 3A arranged between the circumferential grooves 2 communicate with the corners of the third circumferential grooves 2C extending in a zigzag shape.

  Each block 4A1 in the center region 1A located between the first circumferential groove 2A and the third circumferential groove 2C has two sub-grooves 5 each having a bottom raised portion 5a with a shallow groove depth on the third circumferential groove 2C side. It is divided into two block segments X. Each block 4A2 in the center region 1A located between the third circumferential groove 2C and the second circumferential groove 2B also has a bottom raised portion 6a having a shallow groove depth and a narrow groove width on the third circumferential groove 2C side. Are divided into two block segments Y. As shown in FIG. 2, the depth d1 of the bottom raised portion 5a is the groove bottom side from the midpoint position (center position) D1c of the sub lateral groove depth D1 and the tire wear limit display position (from the groove bottom of the circumferential groove 2). 1.6 mm position) It is on the tread surface 1 side from P. The bottom raised portion 6a is similar to the bottom raised portion 5a. In addition, the depth D1 of the sub horizontal groove | channels 5 and 6 is the same depth as the circumferential groove | channel 2 and the horizontal groove | channel 3 which made the groove depth the same here.

  A plurality of shallow groove portions 7 having a width of 1 to 3 mm and a depth of 1 to 4 mm (two are illustrated in FIG. 1) are formed on the tread surface Xa of each block segment X. Each shallow groove portion 7 extends while inclining in the tire width direction, and both ends thereof are located in the block without communicating with the circumferential groove 2. A sipe 8 having one amplitude w (see FIG. 3) extending along the direction in which the shallow groove portion 7 extends is provided on the groove bottom 7 a of each shallow groove portion 7.

  Each sipe 8 having a depth d (see FIG. 4) of less than 10 mm extends in a zigzag manner from one end to the other end of the groove bottom 7a within an amplitude w of 1.0 to 2.0 mm. A sipe 9 formed on the tread surface Xa communicates with both ends of each shallow groove portion 7. The other end of the sipe 9 communicating with the shallow groove portion 7 communicates with the circumferential groove 2. Each sipe 9 inclined in the tire width direction and extending in a straight shape further communicates with a sipe 8 formed on the groove bottom 7 a of the shallow groove portion 7, and both ends of the sipe 8 are circumferential grooves via the sipe 9. 2 communicates indirectly.

  Shallow grooves 10 having a width of 1 to 3 mm and a depth of 1 to 4 mm (one is illustrated in the figure) are also formed on the tread surface Ya of each block segment Y and the tread surface 4Ba of the block 4B of the shoulder region 1B. . Each shallow groove portion 10 extends in an inclined direction in the tire width direction in the opposite direction to the shallow groove portion 7, and one end thereof communicates with the second circumferential groove 2 </ b> B and the other end is located in the block.

  The above-described sipe 8 extending along the direction in which the shallow groove portion 10 extends is provided on the groove bottom 10 a of each shallow groove portion 10. The sipe 9 is not provided on the tread surface Ya of the block segment Y and the tread surface 4Ba of the block 4B, and only one end of the sipe 8 directly communicates with the second circumferential groove 2B. In any block, the sipe 8 provided on the groove bottom of the shallow groove portion is configured to communicate with the circumferential groove 2 at least one end, regardless of direct or indirect.

  Shelves 11 are provided on the wall surfaces of the circumferential grooves of each block 4 so as to reinforce each block 4 and improve traction during off-road. As shown in FIG. 5, the shelf portion 11m formed on the groove bottom side of the circumferential groove wall surface 4A1m facing the first circumferential groove 2A of the block 4A1 has a tire wear limit from the groove bottom of the first circumferential groove 2A. It exceeds the display position (position 1.6 mm from the groove bottom) P and protrudes from the midpoint position (center position) D2c of the circumferential groove depth D2 to the position on the groove bottom side.

  The shelf 11n formed on the groove bottom side of the circumferential groove wall surface 4A1n facing the third circumferential groove 2C of the block 4A1 exceeds the tire wear limit display position (position 1.6 mm from the groove bottom) P, This is composed of a plurality of shelves (two illustrated in the figure) that protrude from the groove bottom of the second circumferential groove 2C from the point position (center position) D2c to the position on the groove bottom side. In the example shown in FIG. 1, the bottom raised portion 5a of the sub-lateral groove 5 and the first shelf portion n of the shelf portion 11n are located at the same depth.

  The shelf portion 11p formed on the groove bottom side of the circumferential groove wall surface 4A2p facing the third circumferential groove 2C of the block 4A2 exceeds the tire wear limit display position P, and the midpoint position D2c, like the shelf portion 11n. It is composed of a two-stage shelf that protrudes from the groove bottom of the third circumferential groove 2C to a position closer to the groove bottom, and the bottom raised portion 6a of the sub-lateral groove 6 and the first shelf p of the shelf 11p are the same. It is deep.

  The shelf 11q formed on the groove bottom side of the circumferential groove wall surface 4A2q facing the second circumferential groove 2B of the block 4A2 is the tire wear limit from the groove bottom of the second circumferential groove 2B in the same manner as the shelf 11m. It is composed of a one-stage shelf that exceeds the display position P and protrudes from the midpoint position D2c to a position on the groove bottom side.

  The shelf portion 11r formed on the groove bottom side of the circumferential groove wall surface 4Br facing the second circumferential groove 2B of the block 4B is similar to the shelf portion 11q from the groove bottom of the second circumferential groove 2B to the tire wear limit. It is composed of a one-stage shelf that exceeds the display position P and protrudes from the midpoint position D2c to a position on the groove bottom side.

  The shelf described above reduces clogging of stone, snow, etc. to the circumferential groove 2, ensures good off-road performance by the circumferential groove 2, and reduces damage to the groove bottom of the circumferential groove 2. Is to do. These shelves are provided so as to be in the above-described range, in order to ensure good off-road performance by the circumferential grooves 2 without greatly impairing drainage.

  According to the present invention described above, since the sipe 8 having an amplitude is formed in the groove bottoms 7a and 10a of the shallow groove portions 7 and 10, the opening of the sipe 8 can be suppressed. Abrasion can be improved.

  In addition, when the shallow grooves 7 and 10 disappear due to wear of the block 4, the sipe 8 having an amplitude is exposed on the tread surface, so that a longer edge component can be ensured. For this reason, it is possible to avoid a significant decrease in off-road performance during wear and to ensure higher off-road performance than before.

  When the width and depth of the shallow groove portions 7 and 10 are less than 1 mm, it is difficult to effectively improve the traction property during off-road running due to the reduction of the groove volume. Conversely, when the width of the shallow groove portions 7 and 10 exceeds 3 mm and the depth exceeds 4 mm, the wear resistance deteriorates due to a decrease in block rigidity.

  If the amplitude w of the sipe 8 is less than 1.0 mm, the swing width is too small and it is difficult to effectively suppress the opening of the sipe 8. On the other hand, if it exceeds 2.0 mm, the amplitude becomes too large, so that when a tire that has been vulcanized has been demolded, a sipe molding blade for molding a sipe 8 tends to cause cracks or chips.

  If the depth d of the sipe 8 exceeds 10 mm, the block rigidity is greatly lowered and the wear resistance is deteriorated. The lower limit value is preferably 50% or more of the groove depth of the circumferential groove 2 in terms of off-road performance during wear.

  In the present invention, the sipe 8 is preferably configured to have a zigzag amplitude in the depth direction as shown in FIG. 6, thereby more effectively suppressing the opening of the sipe 8. Therefore, the wear resistance can be further improved.

  Further, the sipe 8 is inclined with respect to the depth direction as shown in FIG. 7 instead of the configuration extending linearly along the depth direction as shown in FIG. Also good.

  The first circumferential groove 2A may have a groove area ratio of 6 to 15% with respect to the entire grounding region of the tread surface 1. If the groove area ratio of the first circumferential groove 2A is smaller than 6%, the drainage performance is reduced. Conversely, if the groove area ratio exceeds 15%, the groove bottom may be damaged during off-road driving due to an increase in the groove width. Since it becomes easy, it is not preferable.

  Each of the second circumferential grooves 2B is preferably arranged in the range of 20 to 30% of the ground contact width K (mm) from the tire ground contact edge E to the tire inner side. If the second circumferential groove 2B is located closer to the tire ground contact E than the position 20% of the ground contact width K, the block width on the ground contact end, and thus the lateral groove length on the ground contact end, will be shortened, resulting in reduced off-road performance. To do. On the contrary, if it is located inside the tire from the position of 30% of the ground contact width K, the block on the ground contact end side becomes too large, and uneven wear resistance (particularly heel and toe wear resistance) decreases. Here, the contact width K is the maximum contact width of the footprint under the conditions of the standard rim defined by JATMA (2004 edition), 60% of the maximum air pressure, and 60% of the maximum load. Further, the entire grounding region of the tread surface 1 is the entire region within the range of the grounding width K.

  The second circumferential groove 2B formed of a see-through groove is formed by inclining the groove portion 2Ba facing each block 4 in an angle range of 3 to 10 ° with respect to the tire circumferential direction T while keeping the same inclination direction with respect to the tire circumferential direction T. It is better to use a see-through groove. When the inclination angle is less than 3 °, the off-road traction is reduced. On the other hand, if it exceeds 10 °, drainage will be reduced.

  The third circumferential groove 3 </ b> C is preferably extended in a zigzag manner with an inclination angle of 5 to 30 ° with respect to the tire circumferential direction T. When the inclination angle is smaller than 5 °, the off-road traction effect by the corner portions 4A1u and 4A2u of the blocks 4A1 and 4A2 facing the third circumferential groove 3C is reduced. , 4A2u is not preferable because uneven wear tends to occur.

  The lateral grooves 3B arranged in the shoulder region 1B are preferably inclined at an angle of 75 to 85 ° with respect to the tire circumferential direction T. When this angle is less than 75 °, the traction property at the time of off-road is lowered, and when it exceeds 85 °, the drainage property and the soil removal property at the time of off-road are deteriorated.

  The groove area of the shoulder region 1B and the center region 1A is the groove area ratio of the shoulder region 1B (groove area ratio with respect to the entire shoulder region within the ground contact width K). The groove area ratio of the center region 1A (groove area ratio with respect to the entire center region) It is better to make it larger. Pneumatic tires that generally employ block patterns with lateral grooves extending in the tire width direction to ensure an edge component are used for rear tires (especially rear tires for light trucks such as pickup trucks). Center wear, where parts wear quickly, is likely to occur. Thus, by reducing the groove area ratio of the center region 1A and increasing the groove area ratio of the shoulder region 1B in this way, the center wear can be improved.

  The shallow groove portion 7 described above is located in the block without both ends communicating with the circumferential groove 2. However, like the shallow groove portion 10, one end may communicate with the circumferential groove 2. The shallow groove portions 7 and 10 according to the present invention may be those having at least one end located in the block so as not to communicate with the circumferential groove 2.

  Further, in place of the above-described configuration, the shelf portion 11 exceeds the tire wear limit display position P from the groove bottom of the circumferential groove 2 and has a midpoint position D2c of the circumferential groove depth D2 as shown in FIG. You may make it consist of the base part 11X which protrudes to the position of the groove bottom side, and the inclination part 11Y which inclines while narrowing from this base part 11X, and extends to the tread surface 1 side.

  The present invention can be preferably used particularly for a pneumatic tire used for a four-wheel drive vehicle, a light truck, or the like, but is not limited thereto.

  The tire of the present invention having the structure shown in FIG. 1 in which the tire size is common to LT245 / 75R16 and the zigzag sipe is provided at the groove bottom of the shallow groove portion, and the sipe provided at the groove bottom of the shallow groove portion in the present invention tire is straight. Each of the conventional tires was made into a shape.

  In the tire of the present invention, the shallow groove has a width of 2 mm, a depth of 2 mm, a sipe amplitude of 1.5 mm, and a depth of 9 mm. The conventional tire has the same structure as the tire of the present invention except that the sipe amplitude is 0 mm.

  In each test tire, the groove area ratio of the first circumferential groove is 6%, the second circumferential groove is 25% of the ground contact width, the inclination angle of the groove portion of the second circumferential groove is 5 °, and the third circumference. The inclination angle of the direction groove is 20 °, and the inclination angle of the lateral groove in the shoulder region is 80 °.

When each of these test tires was subjected to an evaluation test of off-road performance and wear resistance during 30% wear by the test method shown below, the results shown in Table 1 were obtained.
Off-road performance at 30% wear Each test tire with 30% wear is mounted on a rim with a rim size of 16 x 7 J, and the air pressure is 350 kPa and attached to a large pickup truck with a displacement of 5400 cc. The comparative evaluation about the off-road running condition by was carried out, and the evaluation result was shown as an index value with the conventional tire as 100. The larger this value, the better the off-road performance during wear.
Abrasion resistance Each test tire was mounted on a large pickup truck with a displacement of 5400 cc in the same manner as described above, and traveled 100,000 km at a rate of 30% on the highway, 20% off-road, 30% ordinary paved road, and 20% snow road. After that, the amount of wear was measured, and the evaluation result was shown as an index value with the conventional tire as 100. The higher this value, the better the wear resistance.

表１から、本発明タイヤは、耐摩耗性と摩耗時のオフロード性能を改善できることがわかる。

From Table 1, it can be seen that the tire of the present invention can improve wear resistance and off-road performance during wear.

It is a principal part expanded view of the tread surface which shows one Embodiment of the pneumatic tire of this invention. It is a partial expanded sectional view which shows a sub horizontal groove. It is the elements on larger scale of the sipe formed in the groove bottom of a shallow groove part. It is an expanded sectional view of the block part in which a shallow groove part is located. It is an expanded sectional view of a block containing a shelf. It is an expanded sectional view which shows the other example of the sipe formed in the groove bottom of a shallow groove part. It is an expanded sectional view showing other examples of the sipe formed in the groove bottom of the shallow groove part. It is an expanded sectional view showing other examples of a shelf.

Explanation of symbols

1 tread surface 1A center region 1B shoulder region 2 circumferential groove 2A first circumferential groove 2B second circumferential groove 2C third circumferential groove 3, 3A, 3B lateral groove 4, 4A, 4B block 4A1m, 4A1n, 4A2p, 4A2q , 4Ba Circumferential groove wall surface 4Ba Tread surface 5,6 Sub transverse groove 5a, 6a Bottom raised portion 7, 10 Shallow groove portion 7a, 10a Groove bottom 8 Sipe 11, 11m, 11n, 11p, 11q, 11r Shelf portion EP tire Equatorial surface P tire Wear limit display position T Tire circumferential direction X, Y Block segment Xa, Ya Tread surface D1 Sub-groove depth D2 Circumferential groove depth D1c, D2c Midpoint position d Sipe depth w Sipe amplitude

Claims (13)

  A plurality of circumferential grooves extending in the tire circumferential direction are provided on the tread surface, and lateral grooves extending in the tire width direction are arranged at a predetermined pitch in the tire circumferential direction, and a plurality of blocks are formed by the lateral grooves and the circumferential grooves. And a shallow groove portion having a width of 1 to 3 mm and a depth of 1 to 4 mm is extended in the tire width direction so that at least one end is located in the block, and the groove of the shallow groove portion is formed on the tread surface of the block. A pneumatic tire in which one sipe having an amplitude at the bottom is extended along the direction in which the shallow groove portion extends, and the sipe has a depth of less than 10 mm and an amplitude of 1.0 to 2.0 mm.   The pneumatic tire according to claim 1, wherein the sipe extends with an amplitude in the depth direction and at least one end communicates with the circumferential groove.   The plurality of circumferential grooves are each a first circumferential groove disposed on the tire equator plane, and a second circumferential groove disposed at a position dividing the center region of the tread surface and the shoulder regions on both sides thereof. The pneumatic tire according to claim 1 or 2, wherein:   The pneumatic tire according to claim 3, wherein the first circumferential groove is a straight groove, and a groove area ratio with respect to the entire ground contact region of the tread surface is 6 to 15%.   Each second circumferential groove is arranged in the range of 20 to 30% of the ground contact width from the tire contact end to the inside of the tire, and the groove portion where each second circumferential groove faces each block has the same inclination direction with respect to the tire circumferential direction. The pneumatic tire according to claim 3 or 4, comprising a see-through groove configured to be inclined by 3 to 10 ° with respect to the tire circumferential direction.   A third circumferential groove extending in the tire circumferential direction in a zigzag manner in a range of 5 to 30 ° with respect to the tire circumferential direction is provided between the first circumferential groove and each second circumferential groove. Item 6. The pneumatic tire according to Item 3, 4 or 5.   The pneumatic tire according to any one of claims 3 to 6, wherein the lateral groove disposed in the shoulder region is inclined at an angle of 75 to 85 ° with respect to the tire circumferential direction.   The pneumatic tire according to any one of claims 3 to 7, wherein a groove area ratio of the shoulder region is larger than a groove area ratio of the center region.   The lateral grooves arranged in the center region are arranged at a longer pitch in the tire circumferential direction than the transverse grooves arranged in the shoulder region, and the blocks formed in the center region are divided into block segments by the sub-grooves having a bottom raised portion with a shallow groove depth. The pneumatic tire according to any one of claims 3 to 8, wherein the pneumatic tire is divided and provided with the shallow groove portion and the sipe in each block segment.   The pneumatic tire according to claim 9, wherein the depth of the raised bottom portion is located on the groove bottom side from the middle point of the sub-lateral groove depth and on the tread surface side from the tire wear limit display position.   The pneumatic tire according to any one of claims 1 to 10, wherein a shelf protruding from the groove bottom is provided on the circumferential groove wall surface groove bottom side of each block.   The pneumatic tire according to claim 11, wherein the shelf protrudes from a groove bottom of the circumferential groove to a position closer to the groove bottom than a middle point position of a circumferential groove depth from a tire wear limit display position. The shelf extends from the groove bottom of the circumferential groove beyond the tire wear limit display position, and protrudes from the midpoint position of the circumferential groove depth to the position on the groove bottom side, and is inclined while narrowing the width. The pneumatic tire according to claim 11, further comprising an inclined portion extending toward the tread surface side.

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