JP5577611B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire suitable for heel and toe wear resistance.

  In a pneumatic tire in which a block is formed by a circumferential main groove and a lug groove on the shoulder portion of the tread portion, the drainage is high, so that the traction property at the time of WET is excellent. On the other hand, in this pneumatic tire, there is a concern that heel and toe wear may occur in a block having a lug groove therebetween.

  Conventionally, in the pneumatic tire described in Patent Document 1, a protrusion portion separated from the block is formed on the groove bottom of the lug groove.

  The pneumatic tire of Patent Document 1 attempts to suppress heel and toe wear by suppressing the collapse of the block by the protrusion.

  Further, in the pneumatic tire described in Patent Document 2, the bottom side is separated from the block main body side while separating the block into the block main body and the kick-out side small block portion along the lug groove at the block kick-out edge portion. A sipe provided to be inclined is formed.

  The pneumatic tire disclosed in Patent Document 2 is provided with a sipe, makes the small block portion slippery, concentrates wear energy, and suppresses propagation to the block body, thereby preventing the block body heel from acting as an actual block. Trying to suppress andto wear. Moreover, by arranging the sipe to be inclined, it is possible to easily release the kicking side of the block body to the side of the lateral groove adjacent to it when rotating, so that the ground pressure on the kicking side is reduced, He is trying to further reduce heel and toe wear.

Japanese Patent Laid-Open No. 9-24709 JP 11-78429 A

  However, when the pneumatic tire is brought into contact with the ground, the outer side in the tire width direction of the lug groove tends to be larger than the inner side in the tire width direction due to the deformation of each block with the lug groove in between. For this reason, on the tread surface of the block, the heel and toe wear occurs more significantly on the outer side in the tire width direction than on the inner side in the tire width direction, and there is a possibility that the amount of the step is increased. In Patent Document 1 and Patent Document 2, although heel and toe wear can be suppressed, the effect of suppressing the difference in level difference between the tire width direction outer side and the tire width direction inner side is small.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve heel and toe abrasion resistance.

In order to solve the above-described problems and achieve the object, the pneumatic tire of the present invention extends in the tire circumferential direction by at least three circumferential main grooves extending in the tire circumferential direction on the tread surface. In a pneumatic tire in which a rib is formed and a block row in which at least one rib is divided in the tire circumferential direction is formed by a plurality of lug grooves communicating with the circumferential main grooves adjacent in the tire width direction. The lug groove is formed to have a groove depth of 20 [%] or more and 80 [%] or less of the groove depth in the circumferential main groove that communicates, and the minimum dimension of the groove width is 5.0 [mm]. It is set above, and at the tire width direction end of the block row, the groove width Win inside the tire width direction and the groove width Wout outside the tire width direction are set in a range of Wout / Win ≦ 0.85 , And groove width W reaches the groove width Wout of n, the groove width of the lug grooves, characterized in that it is formed as narrowed midway smaller than the groove width Wout.

  According to this pneumatic tire, even if the outer side in the tire width direction of the lug groove tends to open larger than the inner side in the tire width direction due to the deformation of the block row with the lug groove in between, the tire width direction The difference in the degree of opening between the inner groove width Win and the outer groove width Wout in the tire width direction can be made small or the same. As a result, on the tread surface of the block row, a situation in which heel and toe wear occurs more significantly on the outer side in the tire width direction than on the inner side in the tire width direction is reduced, and the step amount is reduced. Therefore, the heel and toe wear resistance can be improved.

  In the pneumatic tire of the present invention, the groove width Win on the inner side in the tire width direction and the groove width Wout on the outer side in the tire width direction are set in a range of 0.25 ≦ Wout / Win ≦ 0.85. It is preferable to improve the heel and toe wear resistance and balance the drainage performance at a high level.

  Further, in the pneumatic tire of the present invention, the tire width direction dimension S of the rib in which the block row is formed is 0.80 ≦ S / SS with respect to the tire width direction dimension SS of the rib closest to the tire equator plane. It is set in the range of ≦ 1.20.

  According to this pneumatic tire, the traction performance can be maintained by defining the tire width direction dimension S of the block row.

  In the pneumatic tire of the present invention, a plurality of the block rows are formed, and the Wout / Win value is set to be smaller in the block rows arranged on the outer side in the tire width direction.

  According to this pneumatic tire, when the tire is in contact with the ground, the outer side in the tire width direction of the lug groove tends to be wider than the inner side in the tire width direction as the block row is arranged on the outer side in the tire width direction from the tire equatorial plane. In addition, the effect of reducing or making the difference in opening degree between the groove width Win on the inner side in the tire width direction and the groove width Wout on the outer side in the tire width direction can be more remarkably obtained.

  In the pneumatic tire of the present invention, the shoulder portion of the tread portion is formed as the block row, and is set in a range of Wout / Win ≦ 0.75.

  According to this pneumatic tire, when the tire is in contact with the ground, the outer side in the tire width direction of the lug groove tends to be wider than the inner side in the tire width direction as the block row is arranged on the outer side in the tire width direction from the tire equatorial plane. However, by setting the block row of the shoulder portion to Wout / Win ≦ 0.75, the difference in the degree of opening between the groove width Win inside the tire width direction and the groove width Wout outside the tire width direction in the block row of the shoulder portion The effect which can be made small or the same can be obtained more remarkably.

  The pneumatic tire according to the present invention is characterized in that all the ribs are formed as the block rows.

  According to this pneumatic tire, traction performance can be further maintained.

  The pneumatic tire of the present invention is characterized by being applied to a heavy duty pneumatic tire.

  According to this pneumatic tire, since the heavy duty pneumatic tire has a particularly deep groove, the block rigidity tends to decrease. Therefore, there is an advantage that the effect of improving the heel and toe wear can be obtained more remarkably by using the heavy duty pneumatic tire as an application target.

  In the pneumatic tire according to the present invention, on the tread surface of the block row, the situation in which the heel and toe wear occurs more significantly on the outer side in the tire width direction than on the inner side in the tire width direction is reduced, and the amount of step is reduced. Abrasion can be improved.

FIG. 1 is a developed plan view showing a part of a tread portion of a pneumatic tire according to Embodiment 1 of the present invention. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is an enlarged view in a circle in FIG. FIG. 4 is a plan view showing a modification of the lug groove. FIG. 5 is a plan view showing a modification of the lug groove. FIG. 6 is a plan view showing a modification of the lug groove. FIG. 7 is a plan view showing a modification of the lug groove. FIG. 8 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side, and Means the side away from the rotation axis in the tire radial direction. The tire circumferential direction is a circumferential direction with the rotation axis as the central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equatorial plane CL in the tire width direction, and the outer side in the tire width direction means the tire equatorial plane CL in the tire width direction. The side away from. The tire equatorial plane CL is a plane that is orthogonal to the rotational axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1.

  The pneumatic tire 1 of the present embodiment is suitable as a heavy duty pneumatic tire. As shown in FIG. 1, a tread portion 2 made of a rubber member having elasticity and forming an outline of the pneumatic tire 1 is formed on the outermost side in the tire radial direction. Further, when the surface of the tread portion 2, that is, a vehicle (not shown) to which the pneumatic tire 1 is mounted travels, the tread surface 21 that comes into contact with the road surface has at least three (in FIG. 1) extending in the tire circumferential direction. 5) circumferential main grooves 3 are provided. The tread portion 2 is formed with a plurality of (six in FIG. 1) ribs 4 extending in the tire circumferential direction by the circumferential main grooves 3. Further, the tread portion 2 includes a block row 40 in which at least one rib 4 is divided into a plurality of blocks 41 in the tire circumferential direction by a plurality of lug grooves 5 communicating with circumferential main grooves 3 adjacent in the tire width direction. Is formed.

  In addition, the bottom upper part 6 may be formed in the groove bottom 51 of the lug groove 5 which forms the block 41. As shown in FIG. 2, the bottom upper portion 6 is formed so as to protrude outward in the tire radial direction so as to raise the groove bottom 51 while continuing to the side wall 52 of the lug groove 5. The bottom upper portion 6 has the effect of improving the rigidity of the block 41, suppressing heel and toe wear, and maintaining traction.

  The groove depth h of the lug groove 5 is set in a range of 0.2 ≦ h / H with respect to the groove depth H of the circumferential main groove 3 that communicates. That is, the groove depth h of the lug groove 5 is set to a range of 20 [%] or more of the groove depth H of the circumferential main groove 3. The groove depth H of the circumferential main groove 3 is set in a range of 15 [mm] ≦ H ≦ 26 [mm]. The groove depth h of the lug groove 5 is equal to or less than the groove depth H of the circumferential main groove 3, and is in the range of 0.2 ≦ h / H ≦ 1.0, that is, 20 [%] or more and 100 [%]. It is preferable to set the following range.

  Moreover, the groove width W which is the dimension between the opening edges 53 opened in the tread part 21 of the tread part 2 is set to 5.0 [mm] or more. That is, the lug groove 5 has a minimum dimension of the groove width W that divides the rib 4 into the blocks 41 in the tire circumferential direction and is secured to 5.0 [mm] or more. In addition, it is preferable that the groove width W of the lug groove 5 is set in the range of 5.0 [mm] ≦ W ≦ 20 [mm].

  Further, as shown in FIG. 3, the lug groove 5 is an end in the tire width direction of the block row 40, and a groove width Win on the inner side in the tire width direction and a groove width Wout on the outer side in the tire width direction are Wout / Win ≦ 0. A range of 85 is set. That is, the lug groove 5 is formed such that the groove width Wout on the outer side in the tire width direction is smaller than the groove width Win on the inner side in the tire width direction at the opening end that opens in the tire width direction. In addition, the lug groove 5 relates to the groove width at the end of the block row 40 in the tire width direction, and the groove width Win on the inner side in the tire width direction and the groove width Wout on the outer side in the tire width direction are 0.25 ≦ Wout / Win ≦ 0. .85 is preferable in order to balance the improvement in heel and toe wear resistance and the drainage performance at a high level.

  Here, as shown in FIG. 3, the lug groove 5 has a groove width from the opening end of the groove width Win that opens to the inner side in the tire width direction to the opening end of the groove width Wout that opens to the outer side in the tire width direction. It is preferable that the opening edge 53 of the lug groove 5 is linearly formed so as to continuously decrease from Win to the groove width Wout.

  As a modification of the lug groove 5, as shown in FIG. 4, from the opening end of the groove width Win that opens in the tire width direction to the opening end of the groove width Wout that opens in the tire width direction outside, The opening edge 53 of the lug groove 5 may be formed in a curved shape so as to continuously decrease from the groove width Win to the groove width Wout.

  Further, as a modification of the lug groove 5, as shown in FIG. 5, from the opening end of the groove width Win that opens in the tire width direction to the opening end of the groove width Wout that opens outward in the tire width direction, The opening edge 53 of the lug groove 5 is formed to be bent from the groove width Win to the groove width Wout so as to be halfway as shown by a solid line or continuously from the middle as shown by a one-dot chain line. Also good. Although not explicitly shown in the drawing, as a modification of the lug groove 5, the gap between the opening end of the groove width Win that opens in the tire width direction to the opening end of the groove width Wout that opens outward in the tire width direction, The opening edge 53 of the lug groove 5 may be formed to be curved so as to reach the groove width Wout from the groove width Win, and to become smaller halfway or continuously from the middle.

  As a modification of the lug groove 5, as shown in FIG. 6, from the opening end of the groove width Win that opens in the tire width direction to the opening end of the groove width Wout that opens outward in the tire width direction, The opening edge 53 of the lug groove 5 is bent (shown by a solid line) or curved (shown by an alternate long and short dash line) so that the groove width Win reaches the groove width Wout and the groove width of the lug groove 5 is narrowed in the middle. It may be. In this case, the minimum dimension of the groove width W of the lug groove 5 can be a constricted position.

  Further, as a modified example of the lug groove 5, as shown in FIG. 7, from the opening end of the groove width Win opening in the tire width direction to the opening end of the groove width Wout opening outward in the tire width direction, The opening edge 53 of the lug groove 5 is bent (shown by a solid line) or curved (shown by an alternate long and short dash line) so that the groove width Win reaches the groove width Wout and the groove width of the lug groove 5 increases in the middle. May be.

  In the pneumatic tire 1 of the present embodiment thus configured, the lug groove 5 has a groove width Wout on the outer side in the tire width direction than the groove width Win on the inner side in the tire width direction at the opening end that opens in the tire width direction. Is formed small.

  According to the pneumatic tire 1, even when the tire is in contact with the ground, the outer side in the tire width direction of the lug groove 5 tends to be larger than the inner side in the tire width direction due to the deformation of each block 41 with the lug groove 5 in between. The difference in the degree of opening between the groove width Win on the inner side in the tire width direction and the groove width Wout on the outer side in the tire width direction can be made small or the same. As a result, on the tread surface 21 of the block 41, a situation in which heel and toe wear is more noticeably generated on the outer side in the tire width direction than on the inner side in the tire width direction is reduced, and the step amount is reduced. Accordingly, it is possible to improve the heel and toe wear resistance.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 1, the tire width direction dimension S of the rib 4 in which the block row 40 is formed is the tire width direction of the rib 4 closest to the tire equatorial plane CL. The dimension SS is set in a range of 0.80 ≦ S / SS ≦ 1.20. The tire width direction dimensions S and SS of the rib 4 are the maximum dimensions in the tire width direction obtained by projecting the outer shape of the rib 4 in the tire circumferential direction.

  In FIG. 1, all of the six ribs 4 are formed as a block row 40, and the two ribs 4A closer to the tire equator plane CL are closest to the tire equator plane CL. Accordingly, the tire width direction dimension S of the other ribs 4B and 4C is set in the range of 0.80 ≦ S / SS ≦ 1.20 with respect to the tire width direction dimension SS of the rib 4A. Further, when the rib 4 on which the target block row 40 is formed is one of the two ribs 4A close to the tire equatorial plane CL, one rib 4A with respect to the tire width direction dimension SS of the other rib 4A. The tire width direction dimension S is set in a range of 0.80 ≦ S / SS ≦ 1.20. Although not clearly shown in the drawing, when the rib 4 is formed on the tire equator plane CL, the rib 4 becomes the rib 4A closest to the tire equator plane CL.

  According to the pneumatic tire 1, the traction performance can be maintained by defining the tire width direction dimension S of the block row 40. In terms of traction performance, it is preferable that all the ribs 4 are formed as a block row 40 as shown in FIG.

  Further, in the pneumatic tire 1 of the present embodiment, a plurality of block rows 40 are formed, and the value of Wout / Win is set smaller for the block row 40 arranged on the outer side in the tire width direction.

  In FIG. 1, all of the six ribs 4 are formed as a block row 40, and the block row on the outer side in the tire width direction with respect to the Wout / Win value of the two block rows 40A near the tire equatorial plane CL. The Wout / Win value of 40B is small, and the Wout / Win value of the block row 40C outside the tire width direction is smaller than the Wout / Win value of the block row 40B outside the tire width direction. That is, the groove width Wout on the outer side in the tire width direction of the lug groove 5 is smaller in the block row 40 arranged on the outer side in the tire width direction than the tire equatorial plane CL, or the groove width Win on the inner side in the tire width direction of the lug groove 5 is smaller. large.

  According to the pneumatic tire 1, the outer side in the tire width direction of the lug groove 5 opens larger than the inner side in the tire width direction as the block row 40 is arranged on the outer side in the tire width direction from the tire equatorial plane CL when the tire contacts the ground. Even if it exists in the tendency, the effect which can make the difference of the opening degree of the groove width Win inside a tire width direction and the groove width Wout outside a tire width direction small or the same can be acquired more notably.

  Moreover, in the pneumatic tire 1 of the present embodiment, the rib 4 of the shoulder portion that is the outermost side in the tire width direction of the tread portion 2 is formed as a block row 40 (40C), and Wout / Win ≦ 0.75. Is set in the range. The lug groove 5 of the block row 40 (40C) of the shoulder portion has a groove width Win on the inner side in the tire width direction and a groove width Wout on the outer side in the tire width direction in a range of 0.25 ≦ Wout / Win ≦ 0.75. It is preferable that the heel and toe wear resistance is improved and the drainage is balanced at a high level.

  That is, the block row 40 (40C) of the shoulder portion has Wout / Win ≦ 0.75, and compared with the block row 40 set in the range of Wout / Win ≦ 0.85, the tire width of the lug groove 5 The difference between the groove width Wout on the outer side in the direction and the groove width Win on the inner side in the tire width direction is large.

  According to this pneumatic tire 1, when the tire is in contact with the ground, the outer side in the tire width direction of the lug groove 5 is wider than the inner side in the tire width direction in the block row 40 arranged on the outer side in the tire width direction from the tire equatorial plane CL. There is a tendency. For this reason, by setting Wout / Win ≦ 0.75 for the block row 40 (40C) of the shoulder portion, the groove width Win on the inner side in the tire width direction and the outer side in the tire width direction in the block row 40 (40C) of the shoulder portion are set. The effect of making the difference in the opening degree of the groove width Wout small or the same can be obtained more remarkably.

  Moreover, in the pneumatic tire 1 of this Embodiment, it is preferable to make a heavy load pneumatic tire into an application object. The heavy duty pneumatic tire has a particularly deep groove depth, so that the block rigidity tends to decrease. Therefore, there is an advantage that the effect of improving the heel and toe wear can be obtained more remarkably by using the heavy duty pneumatic tire as an application target.

  In the embodiment described above, an even number (six in FIG. 1) of ribs 4 are formed by the odd number (seven in FIG. 1) of the circumferential main grooves 3, and two ribs 4 are formed near the tire equatorial plane CL. The rib 4 is disposed, but this is not a limitation. Although not shown in the drawing, for example, a pneumatic tire in which an odd number of ribs 4 are formed by an even number of circumferential main grooves 3 and one rib 4 is disposed on the tire equatorial plane CL is also included in the present invention. It is. However, when one rib 4 is formed as a block row 40 on the tire equatorial plane CL, the groove width on the tire equatorial plane CL is the center of the lug groove in the tire width direction and the groove width is the inner groove width. Corresponding to Win, the groove width at both opening ends that open in the tire width direction is configured to correspond to the groove width Wout on the outer side in the tire width direction.

  FIG. 8 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. In this example, performance tests on traction (WET braking) and heel and toe wear resistance were performed on a plurality of types of pneumatic tires having different conditions.

  In this performance test, a pneumatic tire with a tire size of 275 / 50R22.5 was assembled on a regular rim, filled with regular internal pressure, loaded with regular load, and mounted on all wheels of a 2-D / 4 test vehicle. did. The regular rim here refers to “standard rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. The normal internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load means the “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO.

  The evaluation method is a traction performance test by measuring the braking distance from a speed of 60 km / h three times on a wet asphalt road with a test vehicle equipped with pneumatic tires and indexing the average value. It was. The evaluation result is indicated by an index with the evaluation result of the conventional example as 100, and the larger the index, the better the traction property.

  In the performance test for heel and toe wear resistance, a heel and toe generated on a tread of a block near the tire equator after running on a paved road for 30,000 [km] with a test vehicle equipped with pneumatic tires. The measurement was performed by measuring toe wear ([length direction] × [depth direction]). The evaluation result is indicated by an index with the evaluation result of the conventional example being 100, and the larger the index, the better the heel and toe wear resistance.

  In FIG. 8, the pneumatic tires of Conventional Example 1 to Conventional Example 3 are those in which a block row is formed on the shoulder portion other than the shoulder portion, that is, all ribs are formed as a block row. The ratio of the groove depth h of the lug groove to the groove depth H of the directional main groove is optimized. In the pneumatic tires of Conventional Example 1 and Conventional Example 2, the minimum lug groove width dimension is optimized, but the change in the lug groove width in the tire width direction and the Wout / Win of the block row in the tire width direction And Wout / Win in the block row of the shoulder portion are not optimized. In the pneumatic tire of Conventional Example 3, the change in the lug groove width in the tire width direction and the setting range thereof are optimized, but the minimum dimension of the lug groove width and the Wout / Win of the block row in the tire width direction The change and Wout / Win in the block block of the shoulder portion are not optimized. On the other hand, in the pneumatic tires of Examples 1 to 6, all ribs are formed as block rows, and the ratio of the groove depth h of the lug groove to the groove depth H of the circumferential main groove, the lug The minimum groove width dimension, the change in the lug groove width in the tire width direction, and the setting range thereof are optimized. In the pneumatic tire of Example 5, the change in Wout / Win of the block row in the tire width direction is further optimized. In the pneumatic tire of Example 6, the change in Wout / Win of the block row in the tire width direction and the Wout / Win in the block row of the shoulder portion are further optimized.

  As shown in the test results of FIG. 8, it can be seen that the pneumatic tires of Examples 1 to 6 have improved traction and heel and toe wear resistance.

  As described above, the pneumatic tire according to the present invention is suitable for improving the heel and toe wear resistance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 21 Tread surface 3 Circumferential main groove 4 (4A, 4B, 4C) Rib 40 (40A, 40B, 40C) Block row 41 Block 5 Lug groove 51 Groove bottom 52 Side wall 53 Open edge 6 Bottom upper part CL Tire equatorial plane S, SS Tire width direction dimension W (Win, Wout) Groove width

Claims (7)

Ribs extending in the tire circumferential direction are formed on the tread surface of the tread portion by at least three circumferential main grooves extending in the tire circumferential direction, and communicate with the circumferential main grooves adjacent in the tire width direction. In a pneumatic tire in which a block row in which at least one rib is divided in the tire circumferential direction by a plurality of lug grooves is formed,
The lug groove is formed to have a groove depth of 20 [%] or more and 80 [%] or less of the groove depth in the circumferential main groove that communicates, and the minimum dimension of the groove width is 5.0 [mm]. It is set above, and at the tire width direction end of the block row, the groove width Win inside the tire width direction and the groove width Wout outside the tire width direction are set in a range of Wout / Win ≦ 0.85 , The pneumatic tire is characterized in that the groove width Win reaches the groove width Wout, and the lug groove is smaller than the groove width Wout and narrows in the middle .   2. The groove width Win on the inner side in the tire width direction and the groove width Wout on the outer side in the tire width direction are set in a range of 0.25 ≦ Wout / Win ≦ 0.85. Pneumatic tires.   The tire width direction dimension S of the rib in which the block row is formed is set in a range of 0.80 ≦ S / SS ≦ 1.20 with respect to the tire width direction dimension SS of the rib closest to the tire equatorial plane. The pneumatic tire according to claim 1, wherein the pneumatic tire is a tire.   A plurality of the block rows are formed, and the Wout / Win value is set to be smaller for the block rows arranged on the outer side in the tire width direction. The described pneumatic tire.   5. The pneumatic according to claim 1, wherein a shoulder portion of the tread portion is formed as the block row and is set in a range of Wout / Win ≦ 0.75. tire.   The pneumatic tire according to claim 1, wherein all the ribs are formed as the block row.   The pneumatic tire according to claim 1, wherein the pneumatic tire is applied to a heavy duty pneumatic tire.

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