JP2016011027A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve traction performance, lateral grip performance and wear resistance in a balanced manner.SOLUTION: A pneumatic tire 1 includes: inclined grooves 3 inclined to one side with respect to a tire axial direction; and a splice groove 4 for connecting the inclined grooves 3 adjacent to each other in a tire circumferential direction. A block row 15 in which a plurality of blocks 5 are arrayed along the inclined grooves 3 is formed between the inclined grooves 3. The splice groove 4 includes a pair of ends 8 having an angle θ1 of 5 degrees or less with respect to the tire circumferential direction and a center section 9 having an angle θ2 larger than the angle θ1 of the ends 8 with respect to the tire circumferential direction. A maximum length in the tire axial direction of the block row 15 is 60 to 90% of a tread ground contact width.

Description

  The present invention relates to a pneumatic tire that can improve traction performance, lateral grip performance, and wear resistance performance in a well-balanced manner when traveling on rough terrain such as a rally or a dirt trial.

  For example, pneumatic tires for rough terrain used for rallying, etc. have traction performance to firmly grip the road surface to obtain driving force, and side grip performance to suppress tire skidding during cornering Is required.

  For example, the following Patent Document 1 discloses a pneumatic structure having a plurality of circumferential grooves in which a first portion inclined to one side in the tire circumferential direction and a second portion inclined in a direction opposite to the first portion are alternately arranged. Tires have been proposed.

JP 2001-180230 A

  However, such a pneumatic tire has a problem that uneven wear tends to occur in the blocks on both sides of the circumferential groove.

  The present invention has been devised in view of the above problems, and has as its main object to provide a pneumatic tire capable of improving the traction performance, the lateral grip performance and the wear resistance performance in a well-balanced manner.

  The present invention is a pneumatic tire, wherein a plurality of inclined grooves that are inclined to one side with respect to the tire axial direction and are arranged in the tire circumferential direction are formed between the inclined grooves adjacent to each other in the tire circumferential direction. And a plurality of joint grooves arranged in the tire axial direction, and a block row in which a plurality of blocks are arranged along the inclined grooves is formed between the inclined grooves. A pair of end portions each having an angle θ1 of 5 ° or less with respect to the tire circumferential direction, and a central portion having an angle θ2 larger than the angle θ1 of the end portion with respect to the tire circumferential direction, The maximum length in the tire axial direction is 60% to 90% of the tread contact width.

  In the pneumatic tire according to the present invention, it is preferable that the central portion is inclined in a direction opposite to the inclined groove.

  In the pneumatic tire according to the present invention, in the development view of the tread portion, it is preferable that the joint groove is arranged along an inclination axis opposite to the inclination of the inclined groove.

  In the pneumatic tire according to the present invention, it is preferable that the inclined groove is linear, the joint groove is zigzag, and the tread surface of the block is zigzag.

  In the pneumatic tire according to the present invention, the angle of the inclined groove with respect to the tire axial direction is preferably 10 to 50 °.

  In the pneumatic tire according to the present invention, it is desirable that the width of the block in the tire axial direction is 5% to 15% of the tread contact width.

  In the pneumatic tire according to the present invention, it is preferable that the angle θ2 of the central portion is 55 to 75 °.

  In the pneumatic tire according to the present invention, it is desirable that the tread portion has a land ratio of 60% to 75%.

  The pneumatic tire of the present invention is provided with a plurality of inclined grooves inclined to one side with respect to the tire axial direction and a plurality of joint grooves that are connected between the inclined grooves and are aligned in the tire axial direction. ing. Traction performance and lateral grip performance are improved by the edge components in the tire axial direction and tire circumferential direction of such inclined grooves and joint grooves.

  The joint groove includes a pair of end portions each having an angle θ1 of 5 degrees or less with respect to the tire circumferential direction, and a central portion having an angle θ2 larger than the angle θ1 of the end portion with respect to the tire circumferential direction. Yes. Such a joint groove has a large edge component in the tire axial direction at the center. Therefore, the traction performance is further improved.

  A block row in which a plurality of blocks are arranged along the inclined grooves is formed between the inclined grooves. Each block has both ends in the tire circumferential direction that are sandwiched between the ends of the joint grooves adjacent in the tire axial direction. Since both ends of the block have high tire circumferential rigidity, the wear resistance performance of the block is improved.

  Since the block row is formed in a wide range of 60% to 90% of the tread contact width, the tire can exhibit excellent lateral grip performance, traction performance, and wear resistance performance.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. 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 is a development view of a tread portion 2 of a pneumatic tire 1 showing an embodiment of the present invention. The pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment is suitably used as an all-season tire suitable for running on rough terrain, for example.

  As shown in FIG. 1, the tread portion 2 includes a plurality of inclined grooves 3, a plurality of joint grooves 4 connecting between the inclined grooves 3, and a plurality of sections divided by the inclined grooves 3 and the joint grooves 4. A number of blocks 5 are provided.

  A plurality of the inclined grooves 3 are provided at intervals in the tire circumferential direction. The inclined groove 3 is inclined to one side with respect to the tire axial direction. The inclined groove 3 of this embodiment extends upward. The inclined groove 3 extends linearly across the tire equator C, for example, and both ends thereof are located inside the tread portion 2. The inclined groove 3 may be formed by a curved line such as a smooth arc shape or a zigzag shape. Since the inclined groove 3 has edge components in the tire axial direction and the tire circumferential direction, the traction performance and the lateral grip performance of the tire are enhanced.

  The angle α1 of the inclined groove 3 with respect to the tire axial direction is preferably 10 to 50 °. When the angle α1 of the inclined groove 3 is less than 10 °, the edge component in the tire circumferential direction of the inclined groove 3 is reduced, and as a result, the lateral grip performance may not be improved. When the angle α1 of the inclined groove 3 exceeds 50 °, the rigidity of the end pieces 6 and 6 of the block 5 is lowered, and the wear resistance may be deteriorated.

  The groove width W1 of the inclined groove 3 is preferably 4.5% to 8.0% of the tread ground contact width TW. When the groove width W1 of the inclined groove 3 is less than 4.5% of the tread ground contact width TW, mud or the like is easily clogged in the inclined groove 3, and the traction performance may be deteriorated. When the groove width W1 of the inclined groove 3 exceeds 8.0% of the tread ground contact width TW, the volume of the block 5 becomes small, and as a result, the rigidity thereof may be reduced. The groove width W1 of the inclined groove 3 is constant in the present embodiment, but may vary.

  The tread contact width TW is a distance in the tire axial direction between the contact ends Te and Te in a normal state. The normal state is a no-load state in which the tire 1 is assembled with a normal rim and filled with a normal internal pressure. The ground contact Te is defined as the outermost ground contact position of the tread portion 2 when a normal load is applied to the tire 1 in the normal state and grounded to a plane with a camber angle of 0 degree. The dimensions and the like of each part of the tire are values in the normal state unless otherwise specified.

  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 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” The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  A plurality of joint grooves 4 are provided between the inclined grooves 3 and 3. Each joint groove 4 includes a pair of end portions 8 and a central portion 9 connecting the end portions 8 and 8.

  Each end 8 of the joint groove 4 extends from the inclined groove 3 at an angle θ1 of 5 ° or less with respect to the tire circumferential direction. In other words, the end portion 8 of the joint groove 4 extends substantially along the tire circumferential direction. In a preferred embodiment, the end 8 is formed in a straight line extending along the tire circumferential direction. The central portion 9 of the joint groove 4 is inclined at an angle θ2 larger than the angle θ1 of the end portion 8 with respect to the tire circumferential direction. In the present embodiment, the end portion 8 and the central portion 9 are connected so that the angle α3 between the central portion 9 and the end portion 8 becomes an obtuse angle. Thereby, each joint groove | channel 4 of this embodiment is bent and extended in zigzag shape.

  The joint groove 4 enhances the traction performance by the edge component of the central portion 9 in the tire axial direction. Further, the end groove 8 of the joint groove 4 improves lateral grip performance and soil removal. In order to exhibit these actions more effectively, the angle θ1 of the end portion 8 is preferably 3 ° or less, and the angle θ2 of the central portion 9 is preferably 55 to 75 °. When the angle θ2 of the central portion 9 is less than 55 °, the edge component in the tire axial direction of the central portion 9 becomes small, and the traction performance may not be improved. When the angle θ2 of the central portion 9 exceeds 75 °, the rigidity between the end piece 6 and the central piece 7 of the block 5 is lowered, so that the wear resistance performance may be deteriorated.

  The central portion 9 of the joint groove 4 of this embodiment is inclined in the direction opposite to the inclined groove 3. Thereby, the stable traction performance is exhibited at the time of straight running. Also. Since the lateral force caused by the central portion 9 and the inclined groove 3 is canceled out, it helps to reduce conicity.

  The groove width W2 of the joint groove 4 is preferably 4.5% to 8.0% of the tread ground contact width TW. When the groove width W2 of the joint groove 4 is less than 4.5% of the tread contact width TW, mud etc. are easily clogged in the inclined groove 3, and the traction performance may be deteriorated. When the groove width W2 of the joint groove 4 exceeds 8.0% of the tread ground contact width TW, the volume of the block 5 becomes small and its rigidity may be reduced. In particular, the groove width W2 of the joint groove 4 is desirably 5.0 mm or more in order to suppress deterioration of the traction performance.

  In a preferred embodiment, the joint groove 4 is arranged along an inclined axis n1 opposite to the inclined groove 3 in the development view of the tread portion 2 shown in FIG. As a result, a first zigzag groove 10 (a lightly colored region in FIG. 1) in which the inclined groove 3 continues through the joint groove 4 is formed on the inclined axis n1. In the present embodiment, a plurality of first zigzag grooves 10 are formed along the inclined grooves 3.

  Such a first zigzag groove 10 can generate a high frictional force continuously against a side slip when turning, for example, and can further improve the side grip performance. In order to enhance such an action, it is particularly desirable that each connecting portion 11 between the joint groove 4 and the inclined groove 3 is disposed on the inclined axis n1. Further, in the first zigzag groove 10, since the end 8 and the center 9 of the joint groove 4 are inclined in opposite directions with respect to the inclined axis n1, high traction performance can be obtained even during turning. . In order to further improve the lateral grip performance, the intersection angle α2 between the inclined axis n1 and the inclined groove 3 is desirably 80 ° or more.

  FIG. 2 shows a development view of the tread portion 2 of the present embodiment, as in FIG. As shown in FIG. 2, in the preferred embodiment, the joint grooves 4 are arranged along the axis n <b> 2 in the tire circumferential direction. As a result, a second zigzag groove 13 (a lightly colored region in FIG. 2) in which the joint groove 4 continues in the tire circumferential direction via the inclined groove 3 is formed in the tread portion 2. In the present embodiment, a plurality of second zigzag grooves 13 are provided in the tire axial direction. The second zigzag groove 13 of the present embodiment is formed as a substantially trapezoidal wave-shaped zigzag groove having the inclined groove 3, the end portion 8 of the joint groove 4, and the central portion 9 of the joint groove 4 as groove components. The second zigzag groove 13 can smoothly discharge the soil in the groove while improving the traction performance during straight traveling.

  The block 5 integrally includes a pair of end pieces 6 and 6 adjacent to the end portion 8 of the joint groove 4 and a central piece 7 adjacent to the center portion 9 of the joint groove 4. The end piece 6 extends substantially along the tire circumferential direction. The central piece 7 is inclined at θ2 with respect to the tire circumferential direction, like the central portion 9 of the joint groove 4. As a result, the tread surface of the block 5 extends like a zigzag like the joint groove 4.

  Since the end piece 6 of the block 5 has high tire circumferential rigidity, deformation during straight traveling is suppressed, and as a result, wear resistance is improved. On the other hand, during driving or braking, when a very large shearing force in the tire circumferential direction acts on the block 5, the central portion 9 inclined with respect to the tire circumferential direction deforms relatively greatly and acts on the block 5. Stress can be relieved and its durability can be maintained.

  The block 5 is formed in a vertically long shape that is long in the tire circumferential direction, for example. In a preferred embodiment, the width Wb in the tire axial direction of the block 5 is 5% to 15% of the tread contact width TW. When the width Wb of the block 5 is less than 5% of the tread contact width TW, the lateral rigidity of the block 5 is lowered. When the width Wb of the block 5 exceeds 15% of the tread contact width TW, the number of the joint grooves 4 is reduced, and the edge component may be reduced.

  Between the inclined grooves 3 and 3, a block row 15 in which a plurality of blocks 5 are arranged obliquely along the inclined groove 3 is formed. The block row 15 of this embodiment is formed of six blocks 5. The maximum length Wa of the block row 15 in the tire axial direction is determined in a range of 60% to 90% of the tread contact width TW. Thereby, the wide range of the tread part 2 is formed with the said block 5, and the outstanding side grip performance, traction performance, and abrasion resistance performance can be exhibited. When the maximum length Wa of the block row 15 exceeds 90% of the tread contact width TW, the groove width of the joint groove 4 on both sides in the tire axial direction becomes small, and mud etc. easily enters, and the edges in the tire axial direction and the circumferential direction Component may be small.

  The land ratio of the tread portion 2 is preferably 60% to 75%. Accordingly, the rigidity of the block 5 is maintained high while securing the edge component due to the inclined groove 3 and the joint groove 4, and the traction performance, the side grip performance, and the wear resistance performance are improved in a well-balanced manner.

  As mentioned above, although embodiment of this invention was explained in full detail, it cannot be overemphasized that this invention is not limited to illustrated embodiment, and can be deform | transformed and implemented in a various aspect.

A pneumatic tire of size 205 / 65R15 having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1, and the traction performance, lateral grip performance, and wear resistance performance of each sample tire were tested. The main common specifications and test methods for each sample tire are as follows.
Tread contact width TW: 200mm
Groove depth of inclined groove: 8.0mm
Groove depth of joint groove: 8.0mm

<Traction performance / side grip performance>
Test tires were installed on all wheels of a 2000cc four-wheel drive vehicle under the following conditions. The test driver drove the vehicle on a dirt trial course of 2.5 km per lap, and the traction performance and lateral grip performance at that time were evaluated by the test driver's sensuality. The results are displayed with a 5-level rating of 1-5. The larger the value, the better the performance.
Rims: 18x7JJ
Internal pressure: 210kPa

<Abrasion resistance>
After the test run described above, the groove depth of the joint groove was measured at 12 points at equal pitches in the tire circumferential direction for each sample tire. The results were obtained by obtaining an average value of the groove depths of the joint grooves of each sample tire and displaying them in a five-step evaluation of 1 to 5 according to the average groove depth. It shows that abrasion resistance performance is so favorable that a numerical value is large.
Table 1 shows the test results.

  As a result of the test, it was confirmed that the tires of the examples had improved lateral grip performance, traction performance, and wear resistance performance as compared with the tires of the comparative examples. In addition, the same test was performed by changing the tire size, and the same tendency as the test result was confirmed.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 3 Inclined groove 4 Joint groove 5 Block 8 End part 9 Central part 15 Block row

Claims (8)

A pneumatic tire,
In the tread portion, a plurality of inclined grooves inclined to one side with respect to the tire axial direction and aligned in the tire circumferential direction,
A plurality of joint grooves that are connected between the inclined grooves adjacent in the tire circumferential direction and arranged in the tire axial direction are provided;
A block row in which a plurality of blocks are arranged along the inclined grooves is formed between the inclined grooves,
The joint groove includes a pair of end portions each having an angle θ1 of 5 ° or less with respect to the tire circumferential direction, and a center portion having an angle θ2 larger than the angle θ1 of the end portion with respect to the tire circumferential direction. ,
The maximum length of the block row in the tire axial direction is 60% to 90% of the tread contact width.   The pneumatic tire according to claim 1, wherein the central portion is inclined in a direction opposite to the inclined groove.   3. The pneumatic tire according to claim 1, wherein, in the development view of the tread portion, the joint grooves are arranged along an inclination axis opposite to the inclination of the inclined grooves. The inclined groove is linear,
The joint groove has a zigzag shape,
The pneumatic tire according to any one of claims 1 to 3, wherein a tread surface of the block has a zigzag shape.   The pneumatic tire according to any one of claims 1 to 4, wherein an angle of the inclined groove with respect to a tire axial direction is 10 to 50 °.   The pneumatic tire according to any one of claims 1 to 5, wherein a width of the block in the tire axial direction is 5% to 15% of a tread contact width.   The pneumatic tire according to any one of claims 1 to 6, wherein the angle θ2 of the central portion is 55 to 75 °.   The pneumatic tire according to claim 1, wherein the tread portion has a land ratio of 60% to 75%.

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